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list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0706.1514 | Daniel Klauser | D. Klauser, D. V. Bulaev, W. A. Coish and Daniel Loss | Electron and hole spin dynamics and decoherence in quantum dots | 19 pages, 4 figures, review article to appear in a book on
semiconductor quantum bits, edited by O. Benson and F. Henneberger, published
by Pan Stanford Publishing | null | null | null | cond-mat.mes-hall | null | In this article we review our work on the dynamics and decoherence of
electron and hole spins in single and double quantum dots. The first part, on
electron spins, focuses on decoherence induced via the hyperfine interaction
while the second part covers decoherence and relaxation of heavy-hole spins due
to spin-orbit interaction as well as the manipulation of heavy-hole spin using
electric dipole spin resonance.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 16:53:16 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Klauser",
"D.",
""
],
[
"Bulaev",
"D. V.",
""
],
[
"Coish",
"W. A.",
""
],
[
"Loss",
"Daniel",
""
]
] |
0706.1515 | Anastasia Doikou | Anastasia Doikou, Davide Fioravanti, Francesco Ravanini | The generalized non-linear Schrodinger model on the interval | 33 pages, Latex. Minor misprints corrected | Nucl.Phys.B790:465-492,2008 | 10.1016/j.nuclphysb.2007.08.007 | null | hep-th math-ph math.MP nlin.SI | null | The generalized (1+1)-D non-linear Schrodinger (NLS) theory with particular
integrable boundary conditions is considered. More precisely, two distinct
types of boundary conditions, known as soliton preserving (SP) and soliton
non-preserving (SNP), are implemented into the classical $gl_N$ NLS model.
Based on this choice of boundaries the relevant conserved quantities are
computed and the corresponding equations of motion are derived. A suitable
quantum lattice version of the boundary generalized NLS model is also
investigated. The first non-trivial local integral of motion is explicitly
computed, and the spectrum and Bethe Ansatz equations are derived for the
soliton non-preserving boundary conditions.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 16:49:11 GMT"
},
{
"version": "v2",
"created": "Mon, 12 Nov 2007 17:43:59 GMT"
},
{
"version": "v3",
"created": "Wed, 2 Jan 2008 09:55:50 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Doikou",
"Anastasia",
""
],
[
"Fioravanti",
"Davide",
""
],
[
"Ravanini",
"Francesco",
""
]
] |
0706.1516 | Werner Hofer | Werner A Hofer, Gilberto Teobaldi, Nicolas Lorente | Creating pseudo Kondo-resonances by field-induced diffusion of atomic
hydrogen | five pages and four figures | null | 10.1088/0957-4484/19/30/305701 | null | cond-mat.mtrl-sci | null | In low temperature scanning tunneling microscopy (STM) experiments a cerium
adatom on Ag(100) possesses two discrete states with significantly different
apparent heights. These atomic switches also exhibit a Kondo-like feature in
spectroscopy experiments. By extensive theoretical simulations we find that
this behavior is due to diffusion of hydrogen from the surface onto the Ce
adatom in the presence of the STM tip field. The cerium adatom possesses
vibrational modes of very low energy (3-4meV) and very high efficiency (> 20%),
which are due to the large changes of Ce-states in the presence of hydrogen.
The atomic vibrations lead to a Kondo-like feature at very low bias voltages.
We predict that the same low-frequency/high-efficiency modes can also be
observed at lanthanum adatoms.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 16:52:12 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Hofer",
"Werner A",
""
],
[
"Teobaldi",
"Gilberto",
""
],
[
"Lorente",
"Nicolas",
""
]
] |
0706.1517 | Kai Schmidt | Kai P. Schmidt, J. Dorier, Andreas Laeuchli, Frederic Mila | Supersolid phase induced by correlated hopping in spin-1/2 frustrated
quantum magnets | 4 pages; 4 figures; published version | Physical Review Letters 100, 090401 (2008) | 10.1103/PhysRevLett.100.090401 | null | cond-mat.str-el | null | We show that correlated hopping of triplets, which is often the dominant
source of kinetic energy in dimer-based frustrated quantum magnets, produces a
remarkably strong tendency to form supersolid phases in a magnetic field. These
phases are characterized by simultaneous modulation and ordering of the
longitudinal and transverse magnetization respectively. Using Quantum Monte
Carlo and a semiclassical approach for an effective hard-core boson model with
nearest-neighbor repulsion on a square lattice, we prove in particular that a
supersolid phase can exist even if the repulsion is not strong enough to
stabilize an insulating phase at half-filling. Experimental implications for
frustrated quantum antiferromagnets in a magnetic field at zero and finite
temperature are discussed.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 16:57:10 GMT"
},
{
"version": "v2",
"created": "Tue, 30 Oct 2007 13:31:32 GMT"
},
{
"version": "v3",
"created": "Fri, 28 Mar 2008 12:29:29 GMT"
}
] | 2008-03-28T00:00:00 | [
[
"Schmidt",
"Kai P.",
""
],
[
"Dorier",
"J.",
""
],
[
"Laeuchli",
"Andreas",
""
],
[
"Mila",
"Frederic",
""
]
] |
0706.1518 | Evert Rol | Evert Rol, Alexander van der Horst, Klaas Wiersema, Sandeep K. Patel,
Andrew Levan, Melissa Nysewander, Chryssa Kouveliotou, Ralph A.M.J. Wijers,
Nial Tanvir, Dan Reichart, Andrew S. Fruchter, John Graham, Jan-Erik
Ovaldsen, Andreas O. Jaunsen, Peter Jonker, Wilbert van Ham, Jens Hjorth,
Rhaana L.C. Starling, Paul T. O'Brien, Johan Fynbo, David N. Burrows, Richard
Strom | GRB051022: physical parameters and extinction of a prototype dark burst | 18 pages, 1 figure. Accepted to ApJ, includes referee's comments | Astrophys.J. 669 (2007) 1098-1106 | 10.1086/521336 | null | astro-ph | null | GRB051022 was undetected to deep limits in early optical observations, but
precise astrometry from radio and X-ray showed that it most likely originated
in a galaxy at z~0.8. We report radio, optical, near infra-red and X-ray
observations of GRB051022. Using the available X-ray and radio data, we model
the afterglow and calculate the energetics of the afterglow, finding it to be
an order of magnitude lower than that of the prompt emission. The broad-band
modeling also allows us to precisely define various other physical parameters
and the minimum required amount of extinction, to explain the absence of an
optical afterglow. Our observations suggest a high extinction, at least 2.3
magnitudes in the infrared (J) and at least 5.4 magnitudes in the optical (U)
in the host-galaxy restframe. Such high extinctions are unusual for GRBs, and
likely indicate a geometry where our line of sight to the burst passes through
a dusty region in the host that is not directly co-located with the burst
itself.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 16:57:48 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Jul 2007 15:04:07 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Rol",
"Evert",
""
],
[
"van der Horst",
"Alexander",
""
],
[
"Wiersema",
"Klaas",
""
],
[
"Patel",
"Sandeep K.",
""
],
[
"Levan",
"Andrew",
""
],
[
"Nysewander",
"Melissa",
""
],
[
"Kouveliotou",
"Chryssa",
""
],
[
"Wijers",
"Ralph A. M. J.",
""
],
[
"Tanvir",
"Nial",
""
],
[
"Reichart",
"Dan",
""
],
[
"Fruchter",
"Andrew S.",
""
],
[
"Graham",
"John",
""
],
[
"Ovaldsen",
"Jan-Erik",
""
],
[
"Jaunsen",
"Andreas O.",
""
],
[
"Jonker",
"Peter",
""
],
[
"van Ham",
"Wilbert",
""
],
[
"Hjorth",
"Jens",
""
],
[
"Starling",
"Rhaana L. C.",
""
],
[
"O'Brien",
"Paul T.",
""
],
[
"Fynbo",
"Johan",
""
],
[
"Burrows",
"David N.",
""
],
[
"Strom",
"Richard",
""
]
] |
0706.1519 | Chiara Cammarota | Chiara Cammarota and Andrea Cavagna | A novel method for evaluating the critical nucleus and the surface
tension in systems with first order phase transition | 12 pages, 15 figures | J. Chem. Phys. 127, 214703 2007 | 10.1063/1.2802449 | null | cond-mat.stat-mech | null | We introduce a novel method for calculating the size of the critical nucleus
and the value of the surface tension in systems with first order phase
transition. The method is based on classical nucleation theory, and it consists
in studying the thermodynamics of a sphere of given radius embedded in a frozen
metastable surrounding. The frozen configuration creates a pinning field on the
surface of the free sphere. The pinning field forces the sphere to stay in the
metastable phase as long as its size is smaller than the critical nucleus. We
test our method in two first-order systems, both on a two-dimensional lattice:
a system where the parameter tuning the transition is the magnetic field, and a
second system where the tuning parameter is the temperature. In both cases the
results are satisfying. Unlike previous techniques, our method does not require
an infinite volume limit to compute the surface tension, and it therefore gives
reliable estimates even by using relatively small systems. However, our method
cannot be used at, or close to, the critical point, i.e. at coexistence, where
the critical nucleus becomes infinitely large.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:01:33 GMT"
},
{
"version": "v2",
"created": "Thu, 3 Jan 2008 15:17:44 GMT"
}
] | 2008-01-03T00:00:00 | [
[
"Cammarota",
"Chiara",
""
],
[
"Cavagna",
"Andrea",
""
]
] |
0706.1520 | David Asher Levin | Davar Khoshnevisan, David A. Levin and Pedro J. Mendez-Hernandez | On dynamical bit sequences | 25 pages. This a substantial revision of an earlier paper. The
material has been reorganized, and Theorem 1.3 is new | null | null | null | math.PR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Let X^{(k)}(t) = (X_1(t), ..., X_k(t)) denote a k-vector of i.i.d. random
variables, each taking the values 1 or 0 with respective probabilities p and
1-p. As a process indexed by non-negative t, $X^{(k)}(t)$ is
constructed--following Benjamini, Haggstrom, Peres, and Steif (2003)--so that
it is strong Markov with invariant measure ((1-p)\delta_0+p\delta_1)^k. We
derive sharp estimates for the probability that ``X_1(t)+...+X_k(t)=k-\ell for
some t in F,'' where F \subset [0,1] is nonrandom and compact. We do this in
two very different settings:
(i) Where \ell is a constant; and
(ii) Where \ell=k/2, k is even, and p=q=1/2. We prove that the probability is
described by the Kolmogorov capacitance of F for case (i) and Howroyd's
1/2-dimensional box-dimension profiles for case (ii). We also present
sample-path consequences, and a connection to capacities that answers a
question of Benjamini et. al. (2003)
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:38:50 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Jun 2009 21:35:11 GMT"
}
] | 2009-06-10T00:00:00 | [
[
"Khoshnevisan",
"Davar",
""
],
[
"Levin",
"David A.",
""
],
[
"Mendez-Hernandez",
"Pedro J.",
""
]
] |
0706.1521 | Kalpana Bora | Kalpana Bora | $\nu$ masses in a SUSY SO(10) theory with spontaneous CP violation | 4 pages | Indian Jr. of Phys, vol 82(6), p 753-59 (2008) | null | null | hep-ph | null | We propose a possibility of spontaneous CP-violation (SCPV) at high scale in
a SUSY SO(10) theory. The model is L-R symmetric SUSY SO(10) with
\textbf{\noun{10}} and \textbf{126} dimensional Higgs generating fermion
masses, and the CP phase is generated through complex VEV of B-L breaking
\textbf{126} Higgs . The model can have potential application in explaining
$\nu$ masses and leptogenesis as well.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:23:26 GMT"
}
] | 2014-07-28T00:00:00 | [
[
"Bora",
"Kalpana",
""
]
] |
0706.1522 | Paul Romatschke | Paul Romatschke and Ulrike Romatschke | Viscosity Information from Relativistic Nuclear Collisions: How Perfect
is the Fluid Observed at RHIC? | 4 pages, 5 figures; v2: matches published version, title changed by
journal | Phys.Rev.Lett.99:172301,2007 | 10.1103/PhysRevLett.99.172301 | INT PUB 07-14 | nucl-th hep-ph hep-th | null | Relativistic viscous hydrodynamic fits to RHIC data on the centrality
dependence of multiplicity, transverse and elliptic flow for sqrt{s}=200 GeV
Au+Au collisions are presented. For Glauber-type initial conditions, while data
on integrated v_2 is consistent with a ratio of viscosity over entropy density
up to eta/s=0.16, data on minimum bias v_2 seems to favor a much smaller
viscosity over entropy ratio, below the bound from the AdS/CFT conjecture. Some
caveats on this result are discussed.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:19:26 GMT"
},
{
"version": "v2",
"created": "Fri, 26 Oct 2007 17:04:02 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Romatschke",
"Paul",
""
],
[
"Romatschke",
"Ulrike",
""
]
] |
0706.1523 | Lando Sergei K. | M. E. Kazarian, S. K. Lando | Thom polynomials for maps of curves with isolated singularities | 16 pages | null | null | null | math.AG | null | Thom (residual) polynomials in characteristic classes are used in the
analysis of geometry of functional spaces. They serve as a tool in description
of classes Poincar\'e dual to subvarieties of functions of prescribed types. We
give explicit universal expressions for residual polynomials in spaces of
functions on complex curves having isolated singularities and
multisingularities, in terms of few characteristic classes. These expressions
lead to a partial explicit description of a stratification of Hurwitz spaces.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:26:01 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Kazarian",
"M. E.",
""
],
[
"Lando",
"S. K.",
""
]
] |
0706.1524 | Gabriel Ruiz Hernandez | Gabriel Ruiz-Hernandez | Helix, shadow boundary and minimal submanifolds | 15 pages | null | null | null | math.DG | null | Inspired by a Blaschke's work about analytic convex surfaces, we study {\em
shadow boundaries} of Riemannian submanifolds $M$, which are defined by a
parallel vector field along $M$. Since a shadow boundary is just a closed
subset of $M$, first, we will give a condition that guarantee its smoothness.
It depends on the second fundamental form of the submanifold. It is natural to
search for what kind of properties might have such submanifolds of $M$? Could
they be totally geodesic or minimal? Answers to these and related questions are
given in this work.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:26:02 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Ruiz-Hernandez",
"Gabriel",
""
]
] |
0706.1525 | Sakura Schafer-Nameki | Andrei Mikhailov, Sakura Schafer-Nameki | Perturbative study of the transfer matrix on the string worldsheet in
AdS(5)xS(5) | 52 pages, 5 figures; v3: added explanations and complete proof of the
cancellation of the 1-loop logarithmic divergences in Section 6 | null | null | CALT-68-2649 | hep-th | null | Quantum non-local charges are central to the quantum integrability of a
sigma-model. In this paper we study the quantum consistency and UV finiteness
of non-local charges of string theory in AdS(5)xS(5). We use the pure spinor
formalism. We develop the near-flat space expansion of the transfer matrix and
calculate the one-loop divergences. We find that the logarithmic divergences
cancel at the level of one loop. This gives strong support to the quantum
integrability of the full string theory. We develop a calculational setup for
the renormalization group analysis of Wilson line type of operators on the
string worldsheet.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:32:06 GMT"
},
{
"version": "v2",
"created": "Sat, 11 Aug 2007 01:00:50 GMT"
},
{
"version": "v3",
"created": "Mon, 17 Sep 2007 22:12:31 GMT"
}
] | 2007-09-18T00:00:00 | [
[
"Mikhailov",
"Andrei",
""
],
[
"Schafer-Nameki",
"Sakura",
""
]
] |
0706.1526 | Geir Agnarsson | Geir Agnarsson, Magnus Mar Halldorsson | On Colorings of Squares of Outerplanar Graphs | 24 pages, 17 figures | null | null | null | math.CO | null | We study vertex colorings of the square $G^2$ of an outerplanar graph $G$. We
find the optimal bound of the inductiveness, chromatic number and the clique
number of $G^2$ as a function of the maximum degree $\Delta$ of $G$ for all
$\Delta\in \nats$. As a bonus, we obtain the optimal bound of the choosability
(or the list-chromatic number) of $G^2$ when $\Delta \geq 7$. In the case of
chordal outerplanar graphs, we classify exactly which graphs have parameters
exceeding the absolute minimum.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:27:18 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Agnarsson",
"Geir",
""
],
[
"Halldorsson",
"Magnus Mar",
""
]
] |
0706.1527 | Yaroslav Kartashov | Yaroslav V. Kartashov, Fangwei Ye, Victor A. Vysloukh, Lluis Torner | Surface waves in defocusing thermal nonlinear optical media | 15 pages, 5 figures, to appear in Optics Letters | Optics Letters 32, 2260 (2007) | null | null | physics.optics nlin.PS | null | We predict that the interface of materials with defocusing thermal
nonlinearities support stable fundamental and higher-order surface waves when
the opposite edges of the medium are maintained at different temperatures. Such
surface waves exist due to the interplay between repulsion from the interface
and the defocusing thermal nonlinearity that deflect light beams from the bulk
of the medium toward its edges.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:31:34 GMT"
}
] | 2007-09-11T00:00:00 | [
[
"Kartashov",
"Yaroslav V.",
""
],
[
"Ye",
"Fangwei",
""
],
[
"Vysloukh",
"Victor A.",
""
],
[
"Torner",
"Lluis",
""
]
] |
0706.1528 | Maarten Bergvelt | Iana I. Anguelova, Maarten J. Bergvelt | $H_D$-Quantum Vertex Algebras and Bicharacters | 46 pages | null | null | null | math.QA math-ph math.MP | null | We define a new class of quantum vertex algebras, based on the Hopf algebra
$H_D=\mathbb{C}[D]$ of "infinitesimal translations" generated by $D$. Besides
the braiding map describing the obstruction to commutativity of products of
vertex operators, $H_D$-quantum vertex algebras have as main new ingredient a
"translation map" that describes the obstruction of vertex operators to
satisfying translation covariance. The translation map also appears as
obstruction to the state-field correspondence being a homomorphism. We use a
bicharacter construction of Borcherds to construct a large class of
$H_D$-quantum vertex algebras. One particular example of this construction
yields a quantum vertex algebra that contains the quantum vertex operators
introduced by Jing in the theory of Hall-Littlewood polynomials.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:58:30 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Anguelova",
"Iana I.",
""
],
[
"Bergvelt",
"Maarten J.",
""
]
] |
0706.1529 | Geir Agnarsson | Geir Agnarsson | On multipartite posets | 6 pages | null | null | null | math.CO | null | A poset $\mathbf{P} = (X,\preceq)$ is {\em $m$-partite} if $X$ has a
partition $X = X_1 \cup ... \cup X_m$ such that (1) each $X_i$ forms an
antichain in $\mathbf{P}$, and (2) $x\prec y$ implies $x\in X_i$ and $y\in X_j$
where $i<j$. In this article we derive a tight asymptotic upper bound on the
order dimension of $m$-partite posets in terms of $m$ and their bipartite
sub-posets in a constructive and elementary way.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:55:34 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Agnarsson",
"Geir",
""
]
] |
0706.1530 | Eric Vigoda | Thomas P. Hayes, Juan C. Vera, and Eric Vigoda | Randomly coloring planar graphs with fewer colors than the maximum
degree | Preliminary version appeared in STOC 2007. This version contains
revised proofs | null | null | null | math.PR math.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study Markov chains for randomly sampling $k$-colorings of a graph with
maximum degree $\Delta$. Our main result is a polynomial upper bound on the
mixing time of the single-site update chain known as the Glauber dynamics for
planar graphs when $k=\Omega(\Delta/\log{\Delta})$. Our results can be
partially extended to the more general case where the maximum eigenvalue of the
adjacency matrix of the graph is at most $\Delta^{1-\eps}$, for fixed $\eps >
0$.
The main challenge when $k \le \Delta + 1$ is the possibility of "frozen"
vertices, that is, vertices for which only one color is possible, conditioned
on the colors of its neighbors. Indeed, when $\Delta = O(1)$, even a typical
coloring can have a constant fraction of the vertices frozen. Our proofs rely
on recent advances in techniques for bounding mixing time using "local
uniformity" properties.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:55:42 GMT"
},
{
"version": "v2",
"created": "Wed, 31 Aug 2011 14:42:05 GMT"
}
] | 2011-09-01T00:00:00 | [
[
"Hayes",
"Thomas P.",
""
],
[
"Vera",
"Juan C.",
""
],
[
"Vigoda",
"Eric",
""
]
] |
0706.1531 | Olivier Dauchot | F. Lechenault, O. Dauchot, G. Biroli, J.-P. Bouchaud | Critical scaling and heterogeneous superdiffusion across the
jamming/rigidity transition of a granular glass | 4 pages, 8 figures | EPL, 83 (2008) 46003 | 10.1209/0295-5075/83/46003 | null | cond-mat.soft | null | The dynamical properties of a dense horizontally vibrated bidisperse granular
monolayer are experimentally investigated. The quench protocol produces states
with a frozen structure of the assembly, but the remaining degrees of freedom
associated with contact dynamics control the appearance of macroscopic
rigidity. We provide decisive experimental evidence that this transition is a
critical phenomenon, with increasingly collective and heterogeneous
rearrangements occurring at length scales much smaller than the grains'
diameter, presumably reflecting the contact force network fluctuations.
Dynamical correlation time and length scales soar on both sides of the
transition, as the volume fraction varies over a remarkably tiny range ($\delta
\phi/\phi \sim 10^{-3}$). We characterize the motion of individual grains,
which becomes super-diffusive at the jamming transition $\phi_J$, signaling
long-ranged temporal correlations. Correspondingly, the system exhibits
long-ranged four-point dynamical correlations in space that obey critical
scaling at the transition density.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 17:58:53 GMT"
},
{
"version": "v2",
"created": "Fri, 14 Mar 2008 11:30:12 GMT"
}
] | 2008-08-26T00:00:00 | [
[
"Lechenault",
"F.",
""
],
[
"Dauchot",
"O.",
""
],
[
"Biroli",
"G.",
""
],
[
"Bouchaud",
"J. -P.",
""
]
] |
0706.1532 | Boris Kopeliovich | Yu.P. Ivanov, B.Z. Kopeliovich, I. Schmidt | Vector meson production in ultra-peripheral collisions at LHC | Prepared for CERN Workshop Heavy Ion Collisions at the LHC: Last Call
for Predictions. Details will be published elsewhere | null | null | null | hep-ph | null | Vector meson production in ultra-peripheral collisions of heavy ions at LHC
is calculated in VDM and color dipole approaches.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:03:33 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Ivanov",
"Yu. P.",
""
],
[
"Kopeliovich",
"B. Z.",
""
],
[
"Schmidt",
"I.",
""
]
] |
0706.1533 | Kevin Costello | Kevin J. Costello | Renormalisation and the Batalin-Vilkovisky formalism | 88 pages | null | null | null | math.QA hep-th | null | This paper gives a way to renormalise certain quantum field theories on
compact manifolds. Examples include Yang-Mills theory (in dimension 4 only),
Chern-Simons theory and holomorphic Chern-Simons theory. The method is within
the framework of the Batalin-Vilkovisky formalism. Chern-Simons theory is
renormalised in a way respecting all symmetries (up to homotopy). This yields
an invariant of smooth manifolds: a certain algebraic structure on the
cohomology of the manifold tensored with a Lie algebra, which is a "higher
loop" enrichment of the natural Lie-infinity structure.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:15:28 GMT"
},
{
"version": "v2",
"created": "Sun, 17 Jun 2007 19:58:08 GMT"
},
{
"version": "v3",
"created": "Fri, 29 Jun 2007 02:20:00 GMT"
}
] | 2007-06-29T00:00:00 | [
[
"Costello",
"Kevin J.",
""
]
] |
0706.1534 | Simone Speziale | Simone Speziale | Coupling gauge theory to spinfoam 3d quantum gravity | 18 pages | Class.Quant.Grav.24:5139-5160,2007 | 10.1088/0264-9381/24/20/014 | pi-qg-46 | gr-qc hep-th | null | We construct a spinfoam model for Yang-Mills theory coupled to quantum
gravity in three dimensional riemannian spacetime. We define the partition
function of the coupled system as a power series in g_0^2 G that can be
evaluated order by order using grasping rules and the recoupling theory. With
respect to previous attempts in the literature, this model assigns the
dynamical variables of gravity and Yang-Mills theory to the same simplices of
the spinfoam, and it thus provides transition amplitudes for the spin network
states of the canonical theory. For SU(2) Yang-Mills theory we show explicitly
that the partition function has a semiclassical limit given by the Regge
discretization of the classical Yang-Mills action.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:51:04 GMT"
},
{
"version": "v2",
"created": "Thu, 25 Oct 2007 19:17:13 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Speziale",
"Simone",
""
]
] |
0706.1535 | Philippe Andr\'e | Ph. Andr\'e, A. Belloche, F. Motte, N. Peretto | The initial conditions of star formation in the Ophiuchus main cloud:
Kinematics of the protocluster condensations | 17 pages, 8 figures. A&A, in press (v2: notes added to Table 3) | Astron.Astrophys.472:519-535,2007 | 10.1051/0004-6361:20077422 | null | astro-ph | null | The earliest phases of clustered star formation and the origin of the stellar
initial mass function (IMF) are currently much debated. In order to constrain
the origin of the IMF, we investigated the internal and relative motions of
starless condensations and protostars previously detected by us in the dust
continuum at 1.2mm in the L1688 protocluster of the Ophiuchus molecular cloud
complex. The starless condensations have a mass spectrum resembling the IMF and
are therefore likely representative of the initial stages of star formation in
the protocluster. We carried out detailed molecular line observations,
including some N2H+(1-0) mapping, of the Ophiuchus protocluster condensations
using the IRAM 30m telescope. We measured subsonic or at most transonic levels
of internal turbulence within the condensations, implying virial masses which
generally agree within a factor of ~ 2 with the masses derived from the 1.2mm
dust continuum. This supports the notion that most of the L1688 starless
condensations are gravitationally bound and prestellar in nature. We measured a
global one-dimensional velocity dispersion of less than 0.4 km/s between
condensations. This small relative velocity dispersion implies that, in
general, the condensations do not have time to interact with one another before
evolving into pre-main sequence objects. Our observations support the view that
the IMF is partly determined by cloud fragmentation at the prestellar stage.
Competitive accretion is unlikely to be the dominant mechanism at the
protostellar stage in the Ophiuchus protocluster, but it may possibly govern
the growth of starless, self-gravitating condensations initially produced by
gravoturbulent fragmentation toward an IMF, Salpeter-like mass spectrum.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:22:05 GMT"
},
{
"version": "v2",
"created": "Thu, 2 Aug 2007 18:35:14 GMT"
}
] | 2011-03-28T00:00:00 | [
[
"André",
"Ph.",
""
],
[
"Belloche",
"A.",
""
],
[
"Motte",
"F.",
""
],
[
"Peretto",
"N.",
""
]
] |
0706.1536 | Nung-Sing Sze | Chi-Kwong Li and Nung-Sing Sze | Canonical forms, higher rank numerical range, convexity, totally
isotropic subspace, matrix equations | 10 pages. To appear in Proceedings of the American Mathematical
Society | Proc. Amer. Math. Soc., 136:3013-3023. 2008 | 10.1090/S0002-9939-08-09536-1 | null | math.FA quant-ph | null | Results on matrix canonical forms are used to give a complete description of
the higher rank numerical range of matrices arising from the study of quantum
error correction. It is shown that the set can be obtained as the intersection
of closed half planes (of complex numbers). As a result, it is always a convex
set in $\mathcal C$. Moreover, the higher rank numerical range of a normal
matrix is a convex polygon determined by the eigenvalues. These two
consequences confirm the conjectures of Choi et al. on the subject. In
addition, the results are used to derive a formula for the optimal upper bound
for the dimension of a totally isotropic subspace of a square matrix, and
verify the solvability of certain matrix equations.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:33:37 GMT"
},
{
"version": "v2",
"created": "Thu, 24 Jan 2008 02:00:04 GMT"
}
] | 2011-02-10T00:00:00 | [
[
"Li",
"Chi-Kwong",
""
],
[
"Sze",
"Nung-Sing",
""
]
] |
0706.1537 | Chow-Choong Ngeow | C. Ngeow (UIUC) and S. Kanbur (SUNY-Oswego) | Semi-Empirical Cepheid Period-Luminosity Relations in Sloan Magnitudes | 4 pages, 2 tables and 2 figures, ApJ accepted | Astrophys.J.667:35-37,2007 | 10.1086/520802 | null | astro-ph | null | In this paper we derive semi-empirical Cepheid period-luminosity (P-L)
relations in the Sloan ugriz magnitudes by combining the observed BVI mean
magnitudes from the Large Magellanic Cloud Cepheids (LMC) and theoretical
bolometric corrections. We also constructed empirical gr band P-L relations,
using the publicly available Johnson-Sloan photometric transformations, to be
compared with our semi-empirical P-L relations. These two sets of P-L relations
are consistent with each other.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:39:48 GMT"
}
] | 2019-08-19T00:00:00 | [
[
"Ngeow",
"C.",
"",
"UIUC"
],
[
"Kanbur",
"S.",
"",
"SUNY-Oswego"
]
] |
0706.1538 | Chiara Caprini | Camille Bonvin, Chiara Caprini and Ruth Durrer | Superluminal motion and closed signal curves | 10 pages, 3 figures, argument about the Hawking and Ellis theorem on
stable causality added in the conclusion | null | null | null | astro-ph gr-qc hep-th | null | We discuss some properties of Lorentz invariant theories which allow for
superluminal motion. We show that, if signals are always sent forward in time,
closed curves along which signals propagate can be formed. This leads to
problems with causality and with the second law of thermodynamics. Only if one
singles out one frame with respect to which all signals travel forward in time,
the formation of 'closed signal curves' can be prevented. However, the price to
pay is that in some reference frames perturbations propagate towards the past
or towards the future, depending on the direction of emission.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:27:43 GMT"
},
{
"version": "v2",
"created": "Thu, 28 Jun 2007 19:43:47 GMT"
}
] | 2007-06-28T00:00:00 | [
[
"Bonvin",
"Camille",
""
],
[
"Caprini",
"Chiara",
""
],
[
"Durrer",
"Ruth",
""
]
] |
0706.1539 | Geir Agnarsson | Geir Agnarsson, Agust Egilsson, Magnus Mar Halldorsson | Vertex coloring acyclic digraphs and their corresponding hypergraphs | 15 pages | null | null | null | math.CO | null | We consider vertex coloring of an acyclic digraph $\Gdag$ in such a way that
two vertices which have a common ancestor in $\Gdag$ receive distinct colors.
Such colorings arise in a natural way when bounding space for various genetic
data for efficient analysis. We discuss the corresponding {\em down-chromatic
number} and derive an upper bound as a function of $D(\Gdag)$, the maximum
number of descendants of a given vertex, and the degeneracy of the
corresponding hypergraph. Finally we determine an asymptotically tight upper
bound of the down-chromatic number in terms of the number of vertices of
$\Gdag$ and $D(\Gdag)$.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:27:58 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Agnarsson",
"Geir",
""
],
[
"Egilsson",
"Agust",
""
],
[
"Halldorsson",
"Magnus Mar",
""
]
] |
0706.1540 | Nung-Sing Sze | Chi-Kwong Li, Yiu-Tung Poon and Nung-Sing Sze | Condition for the higher rank numerical range to be non-empty | 4 pages; to appear in LAMA | Linear and Multilinear Algebra, 57:365-368, 2009 | 10.1080/03081080701786384 | null | math.FA quant-ph | null | It is shown that the rank-$k$ numerical range of every $n$-by-$n$ complex
matrix is non-empty if $n \ge 3k - 2$. The proof is based on a recent
characterization of the rank-$k$ numerical range by Li and Sze, the Helly's
theorem on compact convex sets, and some eigenvalue inequalities. In
particular, the result implies that $\Lambda_2(A)$ is non-empty if $n \ge 4$.
This confirms a conjecture of Choi et al. If $3k-2>n>0$, an $n$-by-$n$ complex
matrix is given for which the rank-$k$ numerical range is empty. Extension of
the result to bounded linear operators acting on an infinite dimensional
Hilbert space is also discussed.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:36:26 GMT"
},
{
"version": "v2",
"created": "Sun, 4 Nov 2007 13:13:08 GMT"
}
] | 2011-02-10T00:00:00 | [
[
"Li",
"Chi-Kwong",
""
],
[
"Poon",
"Yiu-Tung",
""
],
[
"Sze",
"Nung-Sing",
""
]
] |
0706.1541 | Manuel Morillo | Jos\'e M. Casado, Jos\'e G\'omez-Ord\'o\~nez and Manuel Morillo | Noise induced forced synchronization of global variables in coupled
bistable systems | 4 pages, 4 figures. submitted to Europhysics Letters | null | 10.1209/0295-5075/79/50002 | null | cond-mat.stat-mech | null | We analyze the noise induced synchronization between a collective variable
characterizing a complex system with a finite number of interacting bistable
units and time periodic driving forces. A random phase process associated to
the collective stochastic variable is defined. Its average phase frequency and
average phase diffusion are used to characterize the phenomenon. Our analysis
is based on numerical solutions of the corresponding set of Langevin equations.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:43:45 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Casado",
"José M.",
""
],
[
"Gómez-Ordóñez",
"José",
""
],
[
"Morillo",
"Manuel",
""
]
] |
0706.1542 | Alice K. Harding | Alice K. Harding | Pulsar Physics and GLAST | 5 pages, 2 figures, to appear in Proc. of First GLAST Symposium
(Stanford, Feb. 5-8, 2007), eds. S.Ritz, P.F. Michelson, and C.Meegan, AIP
Conf. Proc | AIP Conf.Proc.921:49-53,2007 | 10.1063/1.2757265 | null | astro-ph | null | Rotation-powered pulsars are excellent laboratories for study of particle
acceleration as well as fundamental physics of strong gravity, strong magnetic
fields, high densities and relativity. I will review the outstanding questions
in pulsar physics and the prospects for finding answers with GLAST LAT
observations. LAT observations should significantly increase the number of
detected radio-loud and radio-quiet gamma-ray pulsars, including millisecond
pulsars, giving much better statistics for elucidating population
characteristics, will measure the high-energy spectrum and the shape of
spectral cutoffs and determine pulse profiles for a variety of pulsars of
different age. Further, measurement of phase-resolved spectra and energy
dependent pulse profiles of the brighter pulsars should allow detailed tests of
magnetospheric particle acceleration and radiation mechanisms, by comparing
data with theoretical models that have been developed.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:58:32 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Harding",
"Alice K.",
""
]
] |
0706.1543 | Anatoly Radyushkin | H.R. Grigoryan, A.V. Radyushkin | Structure of Vector Mesons in Holographic Model with Linear Confinement | 8 pages, RevTex4, references, comments and a figure added. Some
terminoloy changes | Phys.Rev.D76:095007,2007 | 10.1103/PhysRevD.76.095007 | JLAB-THY-07-652 | hep-ph hep-th | null | Wave functions and form factors of vector mesons are investigated in the
holographic dual model of QCD with a smooth oscillator-like wall. We introduce
wave functions conjugate to solutions of the 5D equation of motion and develop
a formalism based on these wave functions, which are very similar to those of a
quantum-mechanical oscillator. For the lowest bound state (rho-meson), we show
that, in this model, the basic elastic form factor exhibits the perfect vector
meson dominance, i.e., it is given by the rho-pole contribution alone. The
electric radius of the rho-meson is calculated, <r^2_rho>_C = 0.655 fm^2, which
is larger than in case of the hard-wall cutoff. The squared radii of higher
excited states are found to increase logarithmically rather than linearly with
the radial excitation number. We calculate the coupling constant f_rho and find
that the experimental value is closer to that calculated in the hard-wall
model.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:30:38 GMT"
},
{
"version": "v2",
"created": "Mon, 18 Jun 2007 19:53:17 GMT"
},
{
"version": "v3",
"created": "Thu, 11 Oct 2007 18:49:51 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Grigoryan",
"H. R.",
""
],
[
"Radyushkin",
"A. V.",
""
]
] |
0706.1544 | David Paneque | D.Paneque, A. Borgland, A. Bovier, E. Bloom, Y. Edmonds, S. Funk, G.
Godfrey, R. Rando, L. Wai, P. Wang | Novel technique for monitoring the performance of the LAT instrument on
board the GLAST satellite | 2 pages, 1 figure, manuscript submitted on behalf of the GLAST/LAT
collaboration to First GLAST symposium proceedings | AIP Conf.Proc.921:562-563,2007 | 10.1063/1.2757452 | SLAC-PUB-12562 | astro-ph | null | The Gamma-ray Large Area Space Telescope (GLAST) is an observatory designed
to perform gamma-ray astronomy in the energy range 20 MeV to 300 GeV, with
supporting measurements for gamma-ray bursts from 10 keV to 25 MeV. GLAST will
be launched at the end of 2007, opening a new and important window on a wide
variety of high energy astrophysical phenomena . The main instrument of GLAST
is the Large Area Telescope (LAT), which provides break-through high-energy
measurements using techniques typically used in particle detectors for collider
experiments. The LAT consists of 16 identical towers in a four-by-four grid,
each one containing a pair conversion tracker and a hodoscopic crystal
calorimeter, all covered by a segmented plastic scintillator anti-coincidence
shield. The scientific return of the instrument depends very much on how
accurately we know its performance, and how well we can monitor it and correct
potential problems promptly. We report on a novel technique that we are
developing to help in the characterization and monitoring of LAT by using the
power of classification trees to pinpoint in a short time potential problems in
the recorded data. The same technique could also be used to evaluate the effect
on the overall LAT performance produced by potential instrumental problems.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:02:27 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Paneque",
"D.",
""
],
[
"Borgland",
"A.",
""
],
[
"Bovier",
"A.",
""
],
[
"Bloom",
"E.",
""
],
[
"Edmonds",
"Y.",
""
],
[
"Funk",
"S.",
""
],
[
"Godfrey",
"G.",
""
],
[
"Rando",
"R.",
""
],
[
"Wai",
"L.",
""
],
[
"Wang",
"P.",
""
]
] |
0706.1545 | Alejandro Cabrera | Alejandro Cabrera | Base-controlled mechanical systems and geometric phases | 44 pages, 1 figure | null | 10.1016/j.geomphys.2007.11.009 | null | math-ph math.DG math.MP | null | In this paper, we carry a detailed study of mechanical systems with
configuration space $Q\longrightarrow Q/G$ for which the base $Q/G$ variables
are being controlled. The overall system's motion is considered to be induced
from the base one due to the presence of general non-holonomic constraints. It
is shown that the solution can be factorized into dynamical and geometrical
parts. Moreover, under favorable kinematical circumstances, the dynamical part
admits a further factorization since it can be reconstructed from an
intermediate (body) momentum solution, yielding a reconstruction phase formula.
Finally, we apply this results to the study of concrete mechanical systems.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:52:25 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Cabrera",
"Alejandro",
""
]
] |
0706.1546 | Marco Brunella | Marco Brunella | On the dynamics of codimension one holomorphic foliations with ample
normal bundle | 10 pages, 1 figure | null | null | null | math.CV | null | We investigate the accumulation to singular points of leaves of codimension
one foliations whose normal bundle is ample, with emphasis on the nonexistence
of Levi-flat hypersurfaces.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:52:51 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Brunella",
"Marco",
""
]
] |
0706.1547 | Brian Serot | Ying Hu, Jeff McIntire, Brian D. Serot (Indiana University) | Two-loop Corrections for Nuclear Matter in a Covariant Effective Field
Theory | 24 pages, 4 figures | Nucl.Phys.A794:187-209,2007 | 10.1016/j.nuclphysa.2007.08.005 | null | nucl-th | null | Although one-loop calculations provide a realistic description of bulk and
single-particle nuclear properties, it is necessary to examine loop corrections
to develop a systematic finite-density power-counting scheme for the nuclear
many-body problem when loops are included. Moreover, it is imperative to study
exchange and correlation corrections systematically to make reliable
predictions for other nuclear observables. One must also verify that the
natural sizes of the one-loop parameters are not destroyed by explicit
inclusion of many-body corrections. The loop expansion is applied to a chiral
effective hadronic lagrangian; with the techniques of Infrared Regularization,
it is possible to separate out the short-range contributions and to write them
as local products of fields that are already present in our lagrangian. (The
appropriate field variables must be re-defined at each order in loops.) The
corresponding parameters implicitly include short-range effects to all orders
in the interaction, so these effects need not be calculated explicitly. The
remaining (long-range) contributions that must be calculated are nonlocal and
resemble those in conventional nuclear-structure calculations. Calculations at
the two-loop level are carried out to illustrate these techniques at finite
densities and to verify that the coupling parameters remain natural when fitted
to the empirical properties of equilibrium nuclear matter.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 18:53:58 GMT"
},
{
"version": "v2",
"created": "Tue, 12 Jun 2007 19:27:12 GMT"
},
{
"version": "v3",
"created": "Thu, 23 Aug 2007 18:10:04 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hu",
"Ying",
"",
"Indiana University"
],
[
"McIntire",
"Jeff",
"",
"Indiana University"
],
[
"Serot",
"Brian D.",
"",
"Indiana University"
]
] |
0706.1548 | Jeremy D. Schnittman | Jeremy D. Schnittman (U Maryland) | Retaining Black Holes with Very Large Recoil Velocities | 6 pages, 3 figures; Comments welcome | null | 10.1086/522203 | null | astro-ph | null | Recent numerical simulations of binary black hole mergers show the
possibility of producing very large recoil velocities (> 3000 km/s). Kicks of
this magnitude should be sufficient to eject the final black hole from
virtually any galactic potential. This result has been seen as a potential
contradiction with observations of supermassive black holes residing in the
centers of most galaxies in the local universe. Using an extremely simplified
merger tree model, we show that, even in the limit of very large ejection
probability, after a small number of merger generations there should still be
an appreciable fraction (>50%) of galaxies with supermassive black holes today.
We go on to argue that the inclusion of more realistic physics ingredients in
the merger model should systematically increase this retention fraction,
helping to resolve a potential conflict between theory and observation. Lastly,
we develop a more realistic Monte Carlo model to confirm the qualitative
arguments and estimate occupation fractions as a function of the central
galactic velocity dispersion.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:24:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Schnittman",
"Jeremy D.",
"",
"U Maryland"
]
] |
0706.1549 | Andrew Skinner | A. J. Skinner and B.-L. Hu | A Chain-Boson Model for the Decoherence and Relaxation of a Few Coupled
SQUIDs in a Phonon Bath | 13 pages, 8 figures | null | 10.1103/PhysRevB.78.014302 | null | quant-ph cond-mat.mes-hall | null | We develop a "chain-boson model" master equation, within the Born-Markov
approximation, for a few superconducting quantum interference devices (SQUIDs)
coupled into a chain and exchanging their angular momenta with a low
temperature phonon bath. Our master equation has four generators; we
concentrate on the damping and diffusion and use them to study the relaxation
and decoherence of a Heisenberg SQUID chain whose spectrum exhibits critical
point energy-level crossings, entangled states, and pairs of resonant
transitions. We note that at an energy-level crossing the relevant bath
wavelengths are so long that even well-spaced large SQUIDs can partially
exhibit collective coupling to the bath, dramatically reducing certain
relaxation and decoherence rates. Also, transitions into entangled states can
occur even in the case of an independent coupling of each SQUID to the bath.
Finally, the pairs of resonant transitions can cause decaying oscillations to
emerge in a lower energy subspace.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:35:58 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Skinner",
"A. J.",
""
],
[
"Hu",
"B. -L.",
""
]
] |
0706.1550 | Martin Lopez-Corredoira | M. Lopez-Corredoira, J. Betancort-Rijo, J. E. Beckman | Galactic disc warps due to intergalactic accretion flows onto the disc | 4 pages, 1 figure, to be published in: "Pathways through an eclectic
Universe" (ASP Proc.; proceedings of the conference held at Tenerife, Spain
on 23rd-27th April 2007), J. Knappen, T. J. Mahoney, A. Vazdekis (Eds.) | null | null | null | astro-ph | null | The accretion of the intergalactic medium onto the gaseous disc is used to
explain the generation of galactic warps. A cup-shaped distortion is expected,
due to the transmission of the linear momentum; but, this effect is small for
most incident inflow angles and the predominant effect turns out to be the
transmission of angular momentum, i.e. a torque giving an integral-sign shaped
warp. The torque produced by a flow of velocity ~100 km/s and baryon density
~10^{-25} kg/m^3, which is within the possible values for the intergalactic
medium, is enough to generate the observed warps and this mechanism offers
quite a plausible explanation. The inferred rate of infall of matter, ~1
M_sun/yr, to the Galactic disc that this theory predicts agrees with the
quantitative predictions of chemical evolution resolving key issues, notably
the G-dwarf problem.
Sanchez-Salcedo (2006) suggests that this mechanism is not plausible because
it would produce a dependence of the scaleheight of the disc with the
Galactocentric azimuth in the outer disc, but rather than being an objection
this is another argument in favour of the mechanism because this dependence is
actually observed in our Galaxy.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:27:15 GMT"
}
] | 2007-06-12T00:00:00 | [
[
"Lopez-Corredoira",
"M.",
""
],
[
"Betancort-Rijo",
"J.",
""
],
[
"Beckman",
"J. E.",
""
]
] |
0706.1551 | David Paneque | D. Paneque | Study of the Flux and Spectral Variations in the VHE Emission from the
Blazar Markarian 501, with the MAGIC Telescope | 4 pages, 3 figures, manuscript submitted on behalf of the MAGIC
collaboration to the First GLAST Symposium (oral presentation) | AIP Conf.Proc.921:153-156,2007 | 10.1063/1.2757290 | SLAC-PUB-12563 | astro-ph | null | The blazar Markarian 501 (Mrk 501) was observed above 100 GeV with the MAGIC
Telescope during May, June and July 2005. The high sensitivity of the
instrument made possible the detection of the source with high significance in
each of the observing nights. During this observational campaign, the emitted
gamma-ray flux from Mkn 501 was found to vary by one order of magnitude, and
showed a high correlation with spectral changes. Intra-night flux variability
was also observed, with flux-doubling times of ~2 minutes. The data showed a
clear evidence of a spectral peak (in the nuFnu representation) during the
nights when the gamma-ray activity was highest. The location of this spectral
feature was found to be correlated with the emitted gamma-ray flux. In these
proceedings we discuss some of the results of this unprecedented spectral and
temporal analysis of Mrk 501 observations in the very high energy range.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 19:29:15 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Paneque",
"D.",
""
]
] |
0706.1552 | Chris Shrader | C.R. Shrader, P. Reig and D. Kazanas | Fourier resolved spectroscopy of 4U 1728-34: New Insights into Spectral
and Temporal Properties of Low-Mass X-ray Binaries | 16 pages, 5 tables, 5 figures. Accepted for publication in ApJ | null | 10.1086/520832 | null | astro-ph | null | Using archival RXTE data we derive the 2-16 keV Fourier-resolved spectra of
the Atoll source 4U 1728-34 in a sequence of its timing states as its low QPO
frequency spans the range between 6 and 94 Hz. The increase in the QPO
frequency accompanies a spectral transition of the source from its island to
its banana states. The banana-states' Fourier-resolved spectra are well fitted
by a single blackbody component with $kT \sim 2-3$ keV depending on the source
position in the color -- color diagram and the Fourier frequency, thus
indicating that this spectral component is responsible for the source
variability on these timescales. This result is in approximate agreement with
similar behavior exhibited by the Z sources, suggesting that, as in that case,
the boundary layer -- the likely source of the thermal component -- is
supported by radiation pressure. Furthermore, it is found that the iron line at
$\sim$6.6 keV, clearly present in the averaged spectra, not apparent within the
limitations of our measurements in the frequency-resolved spectra irrespective
of the frequency range. This would indicate that this spectral component
exhibits little variability on time scales comprising the interval
$10^{-2}-10^2$ seconds. In the island state the single blackbody model proved
inadequate, particularly notable in our lowest frequency band ($0.008-0.8$ Hz).
An absorbed powerlaw or an additive blackbody plus hard powerlaw model was
required to obtain a satisfactory fit. Statistics do not allow unambiguous
discrimination between these possible scenarios.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:37:09 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Shrader",
"C. R.",
""
],
[
"Reig",
"P.",
""
],
[
"Kazanas",
"D.",
""
]
] |
0706.1553 | Fran\c{c}ois Shindo | Fran\c{c}ois Shindo, James F. Babb, Kate Kirby, and Kouichi Yoshino | Absorption spectrum in the wings of the potassium second resonance
doublet broadened by helium | 2 figures | J. Phys. B, 40 (2007), 2841-2846 | 10.1088/0953-4075/40/14/005 | null | physics.atom-ph astro-ph | null | We have measured the reduced absorption coefficients occurring in the wings
of the potassium 4S-5P doublet lines at 404.414 nm and at 404.720 nm broadened
by helium gas at pressures of several hundred Torr. At the experimental
temperature of 900 K, we have detected a shoulder-like broadening feature on
the blue wing of the doublet which is relatively flat between 401.8 nm and
402.8 nm and which drops off rapidly for shorter wavelengths, corresponding to
absorption from the X doublet Sigma+ state to the C doublet Sigma+ state of the
K-He quasimolecule. The accurate measurements of the line profiles in the
present work will sharply constrain future calculations of potential energy
surfaces and transition dipole moments correlating to the asymptotes He-K(5p),
He-K(5s), and He-K(3d).
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:06:43 GMT"
}
] | 2007-07-10T00:00:00 | [
[
"Shindo",
"François",
""
],
[
"Babb",
"James F.",
""
],
[
"Kirby",
"Kate",
""
],
[
"Yoshino",
"Kouichi",
""
]
] |
0706.1554 | Frank Raischel | F. Raischel, F. Kun, H. J. Herrmann | Continuous Damage Fiber Bundle Model for Strongly Disordered Materials | 10 pages, 13 figures | null | 10.1103/PhysRevE.77.046102 | null | cond-mat.mtrl-sci cond-mat.stat-mech | null | We present an extension of the continuous damage fiber bundle model to
describe the gradual degradation of highly heterogeneous materials under an
increasing external load. Breaking of a fiber in the model is preceded by a
sequence of partial failure events occurring at random threshold values. In
order to capture the subsequent propagation and arrest of cracks, furthermore,
the disorder of the number of degradation steps of material constituents, the
failure thresholds of single fibers are sorted into ascending order and their
total number is a Poissonian distributed random variable over the fibers.
Analytical and numerical calculations showed that the failure process of the
system is governed by extreme value statistics, which has a substantial effect
on the macroscopic constitutive behaviour and on the microscopic bursting
activity as well.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:04:36 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Raischel",
"F.",
""
],
[
"Kun",
"F.",
""
],
[
"Herrmann",
"H. J.",
""
]
] |
0706.1555 | Barak Kol | Vadim Asnin, Dan Gorbonos, Shahar Hadar, Barak Kol, Michele Levi and
Umpei Miyamoto | High and Low Dimensions in The Black Hole Negative Mode | 17 pages, 4 figures. v2: added reference. v3: published version | Class.Quant.Grav.24:5527-5540,2007 | 10.1088/0264-9381/24/22/015 | null | hep-th gr-qc | null | The negative mode of the Schwarzschild black hole is central to Euclidean
quantum gravity around hot flat space and for the Gregory-Laflamme black string
instability. We analyze the eigenvalue as a function of space-time dimension by
constructing two perturbative expansions: one for large d and the other for
small d-3, and determining as many coefficients as we are able to compute
analytically. Joining the two expansions we obtain an interpolating rational
function accurate to better than 2% through the whole range of dimensions
including d=4.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 05:49:51 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Jun 2007 18:39:18 GMT"
},
{
"version": "v3",
"created": "Thu, 1 Nov 2007 10:37:01 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Asnin",
"Vadim",
""
],
[
"Gorbonos",
"Dan",
""
],
[
"Hadar",
"Shahar",
""
],
[
"Kol",
"Barak",
""
],
[
"Levi",
"Michele",
""
],
[
"Miyamoto",
"Umpei",
""
]
] |
0706.1556 | Drago\c{s} Constantin | D. Constantin and Z. S. Siwy | Poisson Nernst-Planck Model of Ion Current Rectification through a
Nanofluidic Diode | 9 pages, 10 figures | null | 10.1103/PhysRevE.76.041202 | null | cond-mat.other | null | We have investigated ion current rectification properties of a recently
prepared bipolar nanofluidic diode. This device is based on a single conically
shaped nanopore in a polymer film whose pore walls contain a sharp boundary
between positively and negatively charged regions. A semi-quantitative model
that employs Poisson and Nernst-Plank equations predicts current-voltage curves
as well as ionic concentrations and electric potential distributions in this
system. We show that under certain conditions the rectification degree, defined
as a ratio of currents recorded at the same voltage but opposite polarities,
can reach values of over a 1000 at a voltage range <-2 V, +2 V>. The role of
thickness and position of the transition zone on the ion current rectification
is discussed as well. We also show that rectification degree scales with the
applied voltage.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:11:22 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Constantin",
"D.",
""
],
[
"Siwy",
"Z. S.",
""
]
] |
0706.1557 | Kazuya Koyama | Kazuya Koyama | The cosmological constant and dark energy in braneworlds | Invited Review for a special Gen. Rel. Grav. issue on Dark Energy, 22
pages, 13 figures, references added | Gen.Rel.Grav.40:421-450,2008 | 10.1007/s10714-007-0552-x | null | astro-ph gr-qc hep-th | null | We review recent attempts to address the cosmological constant problem and
the late-time acceleration of the Universe based on braneworld models. In
braneworld models, the way in which the vacuum energy gravitates in the 4D
spacetime is radically different from conventional 4D physics. It is possible
that the vacuum energy on a brane does not curve the 4D spacetime and only
affects the geometry of the extra-dimensions, offering a solution to the
cosmological constant problem. We review the idea of supersymmetric large extra
dimensions that could achieve this and also provide a natural candidate for a
quintessence field. We also review the attempts to explain the late-time
accelerated expansion of the universe from the large-distance modification of
gravity based on the braneworld. We use the Dvali-Gabadadze-Porrati model to
demonstrate how one can distinguish this model from dark energy models in 4D
general relativity. Theoretical difficulties in this approach are also
addressed.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:00:57 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Jul 2007 09:29:18 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Koyama",
"Kazuya",
""
]
] |
0706.1558 | Gergely Zarand | A.I. Toth, L. Borda, J. von Delft, and G. Zarand | Dynamical conductance in the two-channel Kondo regime of a double dot
system | 11 pages in PRB format | Phys. Rev. B 76, 155318 (2007) | 10.1103/PhysRevB.76.155318 | null | cond-mat.mes-hall cond-mat.str-el | null | We study finite-frequency transport properties of the double-dot system
recently constructed to observe the two-channel Kondo effect [R. M. Potok et
al., Nature 446, 167 (2007)]. We derive an analytical expression for the
frequency-dependent linear conductance of this device in the Kondo regime. We
show how the features characteristic of the 2-channel Kondo quantum critical
point emerge in this quantity, which we compute using the results of conformal
field theory as well as numerical renormalization group methods. We determine
the universal cross-over functions describing non-Fermi liquid vs. Fermi liquid
cross-overs and also investigate the effects of a finite magnetic field.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 09:02:09 GMT"
}
] | 2007-11-27T00:00:00 | [
[
"Toth",
"A. I.",
""
],
[
"Borda",
"L.",
""
],
[
"von Delft",
"J.",
""
],
[
"Zarand",
"G.",
""
]
] |
0706.1559 | Babak H. Serdajeh | B. Seradjeh, C. Weeks, M. Franz (UBC) | Fractionalization in a square-lattice model with time-reversal symmetry | 4 pages, 3 figures, RevTex 4. (v2) improved discussion of lattice
effects and confinement; clearer figures | Phys. Rev. B 77, 033104 (2008) | 10.1103/PhysRevB.77.033104 | null | cond-mat.str-el cond-mat.mes-hall | null | We propose a two-dimensional time-reversal invariant system of essentially
non-interacting electrons on a square lattice that exhibits configurations with
fractional charges e/2. These are vortex-like topological defects in the
dimerization order parameter describing spatial modulation in the electron
hopping amplitudes. Charge fractionalization is established by a simple
counting argument, analytical calculation within the effective low-energy
theory, and by an exact numerical diagonalization of the lattice Hamiltonian.
We comment on the exchange statistics of fractional charges and possible
realizations of the system.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:02:51 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Oct 2007 18:39:21 GMT"
}
] | 2011-08-08T00:00:00 | [
[
"Seradjeh",
"B.",
"",
"UBC"
],
[
"Weeks",
"C.",
"",
"UBC"
],
[
"Franz",
"M.",
"",
"UBC"
]
] |
0706.1560 | Lorenzo Sorbo | Mohamed Anber, Lorenzo Sorbo | Two gravitational shock waves on the AdS_3 brane | 21 pages, 1 figure | JHEP 0710:072,2007 | 10.1088/1126-6708/2007/10/072 | null | hep-th | null | A gravitational shock wave is a solution to Einstein equations describing the
gravitational field of a massless particle. We obtain such a geometry for a
particle moving on a AdS_3 brane embedded in a AdS_4 bulk (the lower
dimensional version of the "locally localized gravity" model of Karch and
Randall). In order to do this, we use two different techniques. First, we solve
directly Einstein equations sourced by a massless particle. Then we boost to
the speed of light the AdS_3 brane black hole solution of Emparan et al while
sending its mass parameter to zero. Surprisingly, we obtain two different
results. We discuss the origin of these two different solutions both in the
bulk and in the CFT picture. As a by-product, we derive the expression for the
shock wave associated to a transversally accelerating particle in AdS_4.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 15:37:43 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Anber",
"Mohamed",
""
],
[
"Sorbo",
"Lorenzo",
""
]
] |
0706.1561 | Fabrizio Illuminati | Salvatore M. Giampaolo, Fabrizio Illuminati | Characterization of separability and entanglement in $(2\times{D})$- and
$(3\times{D})$-dimensional systems by single-qubit and single-qutrit unitary
transformations | 8 pages, 1 figure | Phys. Rev. A 76, 042301 (2007) | 10.1103/PhysRevA.76.042301 | null | quant-ph cond-mat.other hep-th math-ph math.MP | null | We investigate the geometric characterization of pure state bipartite
entanglement of $(2\times{D})$- and $(3\times{D})$-dimensional composite
quantum systems. To this aim, we analyze the relationship between states and
their images under the action of particular classes of local unitary
operations. We find that invariance of states under the action of single-qubit
and single-qutrit transformations is a necessary and sufficient condition for
separability. We demonstrate that in the $(2\times{D})$-dimensional case the
von Neumann entropy of entanglement is a monotonic function of the minimum
squared Euclidean distance between states and their images over the set of
single qubit unitary transformations. Moreover, both in the $(2\times{D})$- and
in the $(3\times{D})$-dimensional cases the minimum squared Euclidean distance
exactly coincides with the linear entropy (and thus as well with the tangle
measure of entanglement in the $(2\times{D})$-dimensional case). These results
provide a geometric characterization of entanglement measures originally
established in informational frameworks. Consequences and applications of the
formalism to quantum critical phenomena in spin systems are discussed.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:05:58 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Jun 2007 13:36:29 GMT"
},
{
"version": "v3",
"created": "Fri, 3 Aug 2007 14:33:42 GMT"
}
] | 2007-10-02T00:00:00 | [
[
"Giampaolo",
"Salvatore M.",
""
],
[
"Illuminati",
"Fabrizio",
""
]
] |
0706.1562 | Stelios Kazantzidis | Lucio Mayer (1,2), Stelios Kazantzidis (3), Piero Madau (4,5), Monica
Colpi (6), Thomas Quinn (7), James Wadsley (8) ((1) ETH Zurich, (2)
University of Zurich, (3) KIPAC, Stanford, (4) UC Santa Cruz, (5) MPA, (6)
University of Milano Bicocca, (7) University of Washington, (8) McMaster
University) | Rapid Formation of Supermassive Black Hole Binaries in Galaxy Mergers
with Gas | Accepted for publication in Science, 40 pages, 7 figures,
Supplementary Information included | Science 316 (2007) 1874-1877 | 10.1126/science.1141858 | null | astro-ph | null | Supermassive black holes (SMBHs) are a ubiquitous component of the nuclei of
galaxies. It is normally assumed that, following the merger of two massive
galaxies, a SMBH binary will form, shrink due to stellar or gas dynamical
processes and ultimately coalesce by emitting a burst of gravitational waves.
However, so far it has not been possible to show how two SMBHs bind during a
galaxy merger with gas due to the difficulty of modeling a wide range of
spatial scales. Here we report hydrodynamical simulations that track the
formation of a SMBH binary down to scales of a few light years following the
collision between two spiral galaxies. A massive, turbulent nuclear gaseous
disk arises as a result of the galaxy merger. The black holes form an eccentric
binary in the disk in less than a million years as a result of the
gravitational drag from the gas rather than from the stars.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:12:35 GMT"
}
] | 2007-07-14T00:00:00 | [
[
"Mayer",
"Lucio",
""
],
[
"Kazantzidis",
"Stelios",
""
],
[
"Madau",
"Piero",
""
],
[
"Colpi",
"Monica",
""
],
[
"Quinn",
"Thomas",
""
],
[
"Wadsley",
"James",
""
]
] |
0706.1563 | Natalia Osipova | Konstantin Avrachenkov (INRIA Sophia Antipolis), Patrick Brown (FT
R&D), Natalia Osipova (INRIA Sophia Antipolis) | Optimal Choice of Threshold in Two Level Processor Sharing | null | null | null | null | cs.NI | null | We analyze the Two Level Processor Sharing (TLPS) scheduling discipline with
the hyper-exponential job size distribution and with the Poisson arrival
process. TLPS is a convenient model to study the benefit of the file size based
differentiation in TCP/IP networks. In the case of the hyper-exponential job
size distribution with two phases, we find a closed form analytic expression
for the expected sojourn time and an approximation for the optimal value of the
threshold that minimizes the expected sojourn time. In the case of the
hyper-exponential job size distribution with more than two phases, we derive a
tight upper bound for the expected sojourn time conditioned on the job size. We
show that when the variance of the job size distribution increases, the gain in
system performance increases and the sensitivity to the choice of the threshold
near its optimal value decreases.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 12:21:53 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Jun 2007 09:45:28 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Avrachenkov",
"Konstantin",
"",
"INRIA Sophia Antipolis"
],
[
"Brown",
"Patrick",
"",
"FT\n R&D"
],
[
"Osipova",
"Natalia",
"",
"INRIA Sophia Antipolis"
]
] |
0706.1564 | Abraham Falcone | A. D. Falcone (1), D. Morris (1), J. Racusin (1), G. Chincarini (2 and
3), A. Moretti (2), P. Romano (2 and 3), D. N. Burrows (1), C. Pagani (1), M.
Stroh (1), D. Grupe (1), S. Campana (2), S. Covino (2), G. Tagliaferri (2),
R. Willingale (4), N. Gehrels (5) ((1) Pennsylvania State University,
(2)INAF-Osservatorio Astronomico di Brera, (3) Universita degli studi di
Milano-Bicocca, (4) University of Leicester, (5) NASA/Goddard Space Flight
Center) | The First Survey of X-ray Flares from Gamma Ray Bursts Observed by
Swift: Spectral Properties and Energetics | accepted by ApJ; 39 pages with 14 figures and 7 tables | null | 10.1086/523296 | null | astro-ph | null | Observations of gamma ray bursts (GRBs) with Swift produced the initially
surprising result that many bursts have large X-ray flares superimposed on the
underlying afterglow. The flares were sometimes intense, had rapid rise and
decay phases, and occurred late relative to the ``prompt'' phase. Some
remarkable flares are observed with fluence comparable to the prompt GRB
fluence. Many GRBs have several flares, which are sometimes overlapping. Short,
intense, repetitive, and late flaring can be most easily understood within the
context of the standard fireball model with the internal engine that powers the
prompt GRB emission in an active state at late times. However, other models for
flares have been proposed. Flare origin can be investigated by comparing the
flare spectra to that of the afterglow and the initial prompt emission. In this
work, we have analyzed all significant X-ray flares from the first 110 GRBs
observed by Swift. From this sample 33 GRBs were found to have significant
X-ray flares, with 77 flares that were detected above the 3$\sigma$ level. In
addition to temporal analysis presented in a companion paper, a variety of
spectral models have been fit to each flare. In some cases, we find that the
spectral fits favor a Band function model, which is more akin to the prompt
emission than to that of an afterglow. We find that the average fluence of the
flares is 2.4e-7 erg/cm^2/s in the 0.2-10 keV energy band, which is
approximately a factor of ten below the average prompt GRB fluence. These
results, when combined with those presented in the companion paper on temporal
properties of flares, supports the hypothesis that most X-ray flares are
late-time activity of the internal engine that spawned the initial GRB; not an
afterglow related effect.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:15:05 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Sep 2007 20:25:42 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Falcone",
"A. D.",
"",
"2 and\n 3"
],
[
"Morris",
"D.",
"",
"2 and\n 3"
],
[
"Racusin",
"J.",
"",
"2 and\n 3"
],
[
"Chincarini",
"G.",
"",
"2 and\n 3"
],
[
"Moretti",
"A.",
"",
"2 and 3"
],
[
"Romano",
"P.",
"",
"2 and 3"
],
[
"Burrows",
"D. N.",
""
],
[
"Pagani",
"C.",
""
],
[
"Stroh",
"M.",
""
],
[
"Grupe",
"D.",
""
],
[
"Campana",
"S.",
""
],
[
"Covino",
"S.",
""
],
[
"Tagliaferri",
"G.",
""
],
[
"Willingale",
"R.",
""
],
[
"Gehrels",
"N.",
""
]
] |
0706.1565 | Michael S. Vogeley | Bharat Ratra (Kansas State University), Michael S. Vogeley (Drexel
University) | The Beginning and Evolution of the Universe | 69 pages. Invited review article for Publications of the Astronomical
Society of the Pacific. Supplementary references, tables, and more concise
PDF file at http://www.physics.drexel.edu/universe | Publ.Astron.Soc.Pac.120:235-265,2008 | 10.1086/529495 | KSUPT-07/1 | astro-ph gr-qc hep-ph hep-th physics.hist-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review the current standard model for the evolution of the Universe from
an early inflationary epoch to the complex hierarchy of structure seen today.
We summarize and provide key references for the following topics: observations
of the expanding Universe; the hot early Universe and nucleosynthesis; theory
and observations of the cosmic microwave background; Big Bang cosmology;
inflation; dark matter and dark energy; theory of structure formation; the cold
dark matter model; galaxy formation; cosmological simulations; observations of
galaxies, clusters, and quasars; statistical measures of large-scale structure;
and measurement of cosmological parameters. We conclude with discussion of some
open questions in cosmology. This review is designed to provide a graduate
student or other new worker in the field an introduction to the cosmological
literature.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:16:45 GMT"
},
{
"version": "v2",
"created": "Tue, 8 Jul 2008 17:59:23 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Ratra",
"Bharat",
"",
"Kansas State University"
],
[
"Vogeley",
"Michael S.",
"",
"Drexel\n University"
]
] |
0706.1566 | Jaya Iyer NN | Jaya NN Iyer | Murre's conjectures and explicit Chow--Kuenneth projectors for some
varieties | 16 pages | null | null | null | math.AG math.AC | null | In this paper, we investigate Murre's conjectures on the structure of
rational Chow groups and exhibit explicit Chow--Kuenneth projectors for some
examples. More precisely, the examples we study are the varieties which have a
nef tangent bundle. For surfaces and threefolds which have a nef tangent bundle
explicit Chow--Kuenneth projectors are obtained which satisfy Murre's
conjectures and the motivic Hard Lefschetz theorem is verified.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:24:48 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Iyer",
"Jaya NN",
""
]
] |
0706.1567 | Michael Zieve | Doug Wiedemann and Michael Zieve | Equivalence of sparse circulants: the bipartite \'Ad\'am problem | 20 pages | null | null | null | math.CO math.NT | null | We consider n-by-n circulant matrices having entries 0 and 1. Such matrices
can be identified with sets of residues mod n, corresponding to the columns in
which the top row contains an entry 1. Let A and B be two such matrices, and
suppose that the corresponding residue sets S_A and S_B have size at most 3. We
prove that the following are equivalent: (1) there are integers u,v mod n, with
u a unit, such that S_A = uS_B + v; (2) there are permutation matrices P,Q such
that A=PBQ. Our proof relies on some new results about vanishing sums of roots
of unity. We give examples showing this result is not always true for denser
circulants, as well as results showing it continues to hold in some situations.
We also explain how our problem relates to the Adam problem on isomorphisms of
circulant directed graphs.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:25:52 GMT"
}
] | 2007-07-16T00:00:00 | [
[
"Wiedemann",
"Doug",
""
],
[
"Zieve",
"Michael",
""
]
] |
0706.1568 | Zhihui Wang | Zhihui Wang, Le Zhang, Jonathan Sagotsky, and Thomas S. Deisboeck | Simulating non-small cell lung cancer with a multiscale agent-based
model | 37 pages, 7 figures | null | null | null | q-bio.CB | null | Background The epidermal growth factor receptor (EGFR) is frequently
overexpressed in many cancers, including non-small cell lung cancer (NSCLC). In
silcio modeling is considered to be an increasingly promising tool to add
useful insights into the dynamics of the EGFR signal transduction pathway.
However, most of the previous modeling work focused on the molecular or the
cellular level only, neglecting the crucial feedback between these scales as
well as the interaction with the heterogeneous biochemical microenvironment.
Results We developed a multiscale model for investigating expansion dynamics
of NSCLC within a two-dimensional in silico microenvironment. At the molecular
level, a specific EGFR-ERK intracellular signal transduction pathway was
implemented. Dynamical alterations of these molecules were used to trigger
phenotypic changes at the cellular level. Examining the relationship between
extrinsic ligand concentrations, intrinsic molecular profiles and microscopic
patterns, the results confirmed that increasing the amount of available growth
factor leads to a spatially more aggressive cancer system. Moreover, for the
cell closest to nutrient abundance, a phase-transition emerges where a minimal
increase in extrinsic ligand abolishes the proliferative phenotype altogether.
Conclusions Our in silico results indicate that, in NSCLC, in the presence of
a strong extrinsic chemotactic stimulus, and depending on the cell's location,
downstream EGFR-ERK signaling may be processed more efficiently, thereby
yielding a migration-dominant cell phenotype and overall, an accelerated
spatio-temporal expansion rate.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:26:11 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Wang",
"Zhihui",
""
],
[
"Zhang",
"Le",
""
],
[
"Sagotsky",
"Jonathan",
""
],
[
"Deisboeck",
"Thomas S.",
""
]
] |
0706.1569 | Matthew Healy | M.D.Healy (for the Pierre Auger Collaboration) | Composition-sensitive parameters measured with the surface detector of
the Pierre Auger Observatory | Contribution to the 30th International Cosmic Ray Conference, Merida
Mexico, July 2007 | null | null | null | astro-ph | null | A key step towards the understanding of the origin of ultra-high energy
cosmic rays is their mass composition. Primary photons and neutrinos produce
markedly different showers from nuclei, while showers of different nuclear
species are not easy to distinguish. To maximise the discrimination with the
Pierre Auger Observatory ideally all mass-sensitive observables should be
combined, but the 10% duty cycle of the fluorescence detector limits the use of
direct measurements of shower maximum at the highest energies. Therefore, we
investigate mass-sensitive observables accessible with the surface detectors
alone. These are the signal risetime in the Cherenkov stations, the curvature
of the shower front, the muon-to-electromagnetic ratio, and the azimuthal
signal asymmetry. Risetime and curvature depend mainly on the depth of the
shower development in the atmosphere, and thus on primary energy and mass. The
muon content of a shower depends on the primary energy and the number of
nucleons, while asymmetry about the shower core is due to geometric effects and
attenuation, which are dependent on the primary mass. The mass sensitivity of
these variables is demonstrated and their application for composition studies
is discussed.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:29:31 GMT"
}
] | 2019-08-13T00:00:00 | [
[
"Healy",
"M. D.",
"",
"for the Pierre Auger Collaboration"
]
] |
0706.1570 | Kevin Scannell | Geoffrey Mess | Lorentz spacetimes of constant curvature | 48 pages, 6 figures | null | null | null | math.DG math-ph math.GT math.MP | null | This paper was first written in 1990, but was never published. In it, the
author presents a novel approach to the study of constant curvature spacetimes
in 2+1 dimensions. A parameterization of flat 2+1-dimensional domains of
dependence is given in terms of measured geodesic laminations. There is also an
interesting reinterpretation of Thurston's Earthquake Theorem involving anti-de
Sitter spacetimes.
With the permission of the author, it will be published for the first time in
a forthcoming issue of Geometriae Dedicata, together with detailed "notes"
outlining the developments in the field in the intervening years. The version
posted here is nearly identical to the original; we merely corrected
typographical errors and occasional notational mistakes, and also updated the
references in the bibliography.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:41:51 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Mess",
"Geoffrey",
""
]
] |
0706.1571 | Piyush Kumar | Piyush Kumar | Connecting String/M Theory to the Electroweak Scale and to LHC Data | PhD Thesis, 320 pages, 63 figures References Added | Fortsch.Phys.55:1123-1280,2008 | 10.1002/prop.200710395 | null | hep-ph hep-ex hep-th | null | The Standard Model of particle physics explains (almost) all observed
non-gravitational microscopic phenomena but has many open theoretical
questions. We are on the threshold of unraveling the mysteries of the Standard
Model and discovering its extension. This could be achieved in the near future
with the help of many experiments in particle physics and cosmology, the LHC in
particular. Assuming that data confirming the existence of new physics beyond
the Standard Model is obtained, one is left with the very important and
challenging task of solving the "Inverse Problem", \emph{viz.} "How can one
deduce the nature of the underlying (perhaps microscopic) theory from data?"
This thesis explores this question in detail, and also proposes an approach to
address the problem in a meaningful way which could prove crucial to the
possible solution to this problem in the future. The proposed approach has
three aspects - a) To systematically study classes of microscopic (string/$M$
theory) constructions to the extent that they could be connected to low energy
physics (electroweak scale), b) To find patterns of experimental observables
which are sensitive to the properties of the underlying theoretical
constructions thereby allowing us to distinguish among different constructions,
and c) To try to get insights about the qualitative features of the theoretical
model from data in a bottom-up approach which complements the top-down approach
and strengthens it as well. This thesis studies all the above aspects in
detail. The methods used and results obtained in this thesis will hopefully be
of great importance in solving the Inverse Problem.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 22:04:04 GMT"
},
{
"version": "v2",
"created": "Thu, 13 Sep 2007 22:39:42 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kumar",
"Piyush",
""
]
] |
0706.1572 | Tomasz Placek Dr. | Leszek Wro\'nski and Tomasz Placek | On Minkowskian Branching Structures | 16 pages | null | null | null | math-ph math.MP | null | Contrary to its initial idea, Belnap's (1992) theory of Branching Space-Times
(BST) has models in which histories do not resemble relativistic space-times or
any other physical space-times. The aim of this paper is to define a certain
class of BST models, called "Minkowskian Branching Structures" (MBS), in which
histories are isomorphic to Minkowski space-time. By focusing on these models
rather than on general BST models, we hope that one may be able to improve on
earlier BST analyzes of physical phenomena. Also, introducing MBS' sets the
stage for recent discussions about whether or not `branching is a bad idea',
physically speaking.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 12:14:29 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Wroński",
"Leszek",
""
],
[
"Placek",
"Tomasz",
""
]
] |
0706.1573 | Adam Brown | Adam R. Brown and Erick J. Weinberg | Thermal derivation of the Coleman-De Luccia tunneling prescription | 28 pages, 5 figures; minor rephrasing, typos corrected | Phys.Rev.D76:064003,2007 | 10.1103/PhysRevD.76.064003 | CU-TP-1178, KIAS-P07025 | hep-th gr-qc | null | We derive the rate for transitions between de Sitter vacua by treating the
field theory on the static patch as a thermal system. This reproduces the
Coleman-De Luccia formalism for calculating the rate, but leads to a modified
interpretation of the bounce solution and a different prediction for the
evolution of the system after tunneling. The bounce is seen to correspond to a
sequence of configurations interpolating between initial and final
configurations on either side of the tunneling barrier, all of which are
restricted to the static patch. The final configuration, which gives the
initial data on the static patch for evolution after tunneling, is obtained
from one half of a slice through the center of the bounce, while the other half
gives the configuration before tunneling. The formalism makes no statement
about the fields beyond the horizon.
This approach resolves several puzzling aspects and interpretational issues
concerning the Coleman-De Luccia and Hawking-Moss bounces. We work in the limit
where the back reaction of matter on metric can be ignored, but argue that the
qualitative aspects remain in the more general case. The extension to tunneling
between anti-de Sitter vacua is discussed.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 02:53:05 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jul 2007 22:25:53 GMT"
},
{
"version": "v3",
"created": "Sat, 1 Sep 2007 03:53:57 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Brown",
"Adam R.",
""
],
[
"Weinberg",
"Erick J.",
""
]
] |
0706.1574 | Sergio L. A. de Queiroz | S.L.A. de Queiroz | Wavelet transforms in a critical interface model for Barkhausen noise | RevTeX, 10 pages, 9 .eps figures; Physical Review E, to be published | Physical Review E 77, 021131 (2008) | 10.1103/PhysRevE.77.021131 | null | cond-mat.stat-mech cond-mat.dis-nn | null | We discuss the application of wavelet transforms to a critical interface
model, which is known to provide a good description of Barkhausen noise in soft
ferromagnets. The two-dimensional version of the model (one-dimensional
interface) is considered, mainly in the adiabatic limit of very slow driving.
On length scales shorter than a crossover length (which grows with the strength
of surface tension), the effective interface roughness exponent $\zeta$ is
$\simeq 1.20$, close to the expected value for the universality class of the
quenched Edwards-Wilkinson model. We find that the waiting times between
avalanches are fully uncorrelated, as the wavelet transform of their
autocorrelations scales as white noise. Similarly, detrended size-size
correlations give a white-noise wavelet transform. Consideration of finite
driving rates, still deep within the intermittent regime, shows the wavelet
transform of correlations scaling as $1/f^{1.5}$ for intermediate frequencies.
This behavior is ascribed to intra-avalanche correlations.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:50:37 GMT"
},
{
"version": "v2",
"created": "Tue, 12 Feb 2008 11:10:58 GMT"
}
] | 2008-03-03T00:00:00 | [
[
"de Queiroz",
"S. L. A.",
""
]
] |
0706.1575 | James D. Meiss | H.R. Dullin and J.D. Meiss | Nilpotent normal form for divergence-free vector fields and
volume-preserving maps | laTeX, 20 pages, 1 figure | Physica D 237, 156-166 (2008) | 10.1016/j.physd.2007.08.014 | null | nlin.CD | null | We study the normal forms for incompressible flows and maps in the
neighborhood of an equilibrium or fixed point with a triple eigenvalue. We
prove that when a divergence free vector field in $\mathbb{R}^3$ has nilpotent
linearization with maximal Jordan block then, to arbitrary degree, coordinates
can be chosen so that the nonlinear terms occur as a single function of two
variables in the third component. The analogue for volume-preserving
diffeomorphisms gives an optimal normal form in which the truncation of the
normal form at any degree gives an exactly volume-preserving map whose inverse
is also polynomial inverse with the same degree.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:01:49 GMT"
}
] | 2013-06-25T00:00:00 | [
[
"Dullin",
"H. R.",
""
],
[
"Meiss",
"J. D.",
""
]
] |
0706.1576 | Suranjana Ghosh | Suranjana Ghosh and J. Banerji | A time frequency analysis of wave packet fractional revivals | 9 pages, 4 figures | J. Phys. B: At. Mol. Opt. Phys. 40 (2007) 3545--3553 | 10.1088/0953-4075/40/17/021 | null | quant-ph | null | We show that the time frequency analysis of the autocorrelation function is,
in many ways, a more appropriate tool to resolve fractional revivals of a wave
packet than the usual time domain analysis. This advantage is crucial in
reconstructing the initial state of the wave packet when its coherent structure
is short-lived and decays before it is fully revived. Our calculations are
based on the model example of fractional revivals in a Rydberg wave packet of
circular states. We end by providing an analytical investigation which fully
agrees with our numerical observations on the utility of time-frequency
analysis in the study of wave packet fractional revivals.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 20:32:25 GMT"
}
] | 2009-04-03T00:00:00 | [
[
"Ghosh",
"Suranjana",
""
],
[
"Banerji",
"J.",
""
]
] |
0706.1577 | Jose Juan Blanco-Pillado | Jose J. Blanco-Pillado, Ken D. Olum and Alexander Vilenkin | Cosmic string formation by flux trapping | 16 pages and 9 figures. (Minor changes and new references added) | Phys.Rev.D76:103520,2007 | 10.1103/PhysRevD.76.103520 | null | hep-th astro-ph cond-mat.supr-con hep-ph | null | We study the formation of cosmic strings by confining a stochastic magnetic
field into flux tubes in a numerical simulation. We use overdamped evolution in
a potential that is minimized when the flux through each face in the simulation
lattice is a multiple of the fundamental flux quantum. When the typical number
of flux quanta through a correlation-length-sized region is initially about 1,
we find a string network similar to that generated by the Kibble-Zurek
mechanism. With larger initial flux, the loop distribution and the Brownian
shape of the infinite strings remain unchanged, but the fraction of length in
infinite strings is increased. A 2D slice of the network exhibits bundles of
strings pointing in the same direction, as in earlier 2D simulations. We find,
however, that strings belonging to the same bundle do not stay together in 3D
for much longer than the correlation length. As the initial flux per
correlation length is decreased, there is a point at which infinite strings
disappear, as in the Hagedorn transition.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 22:40:08 GMT"
},
{
"version": "v2",
"created": "Wed, 1 Aug 2007 18:43:35 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Blanco-Pillado",
"Jose J.",
""
],
[
"Olum",
"Ken D.",
""
],
[
"Vilenkin",
"Alexander",
""
]
] |
0706.1578 | David Nidever | David L. Nidever, Steven R. Majewski, and W. Butler Burton | The Origin of the Magellanic Stream and Its Leading Arm | 31 pages, 26 figures, Accepted for publication in ApJ | Astrophys.J.679:432-459,2008 | 10.1086/587042 | null | astro-ph | null | We explore the Magellanic Stream (MS) using a Gaussian decomposition of the
HI velocity profiles in the Leiden-Argentine-Bonn (LAB) all-sky HI survey. This
decomposition exposes the MS to be composed of two filaments distinct both
spatially (as first pointed out by Putman et al.) and in velocity. Using the
velocity coherence of the filaments, one can be traced back to its origin in
what we identify as the SouthEast HI Overdensity (SEHO) of the Large Magellanic
Cloud (LMC), which includes 30 Doradus. Parts of the Leading Arm (LA) can also
be traced back to the SEHO in velocity and position. Therefore, at least
one-half of the trailing Stream and most of the LA originates in the LMC,
contrary to previous assertions that both the MS and the LA originate in the
Small Magellanic Cloud (SMC) and/or in the Magellanic Bridge. The two MS
filaments show strong periodic, undulating spatial and velocity patterns that
we speculate are an imprint of the LMC rotation curve. If true, then the drift
rate of the Stream gas away from the Magellanic Clouds is ~49 km/s and the age
of the MS is ~1.74 Gyr. The Staveley-Smith et al. high-resolution HI data of
the LMC show gas outflows from supergiant shells in the SEHO that seem to be
creating the LA and LMC filament of the MS. Blowout of LMC gas is an effect not
previously accounted for but one that probably plays an important role in
creating the MS and LA.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:07:32 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Feb 2008 22:53:49 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Nidever",
"David L.",
""
],
[
"Majewski",
"Steven R.",
""
],
[
"Burton",
"W. Butler",
""
]
] |
0706.1579 | Lesfari Ahmed | A. Lesfari | Integrable systems and complex geometry | 45 pages | null | null | null | math.DS math.AG | null | In this paper, we discuss an interaction between complex geometry and
integrable systems. Section 1 reviews the classical results on integrable
systems. New examples of integrable systems, which have been discovered, are
based on the Lax representation of the equations of motion. These systems can
be realized as straight line motions on a Jacobi variety of a so-called
spectral curve. In section 2, we study a Lie algebra theoretical method leading
to integrable systems and we apply the method to several problems. In section
3, we discuss the concept of the algebraic complete integrability (a.c.i.) of
hamiltonian systems. Algebraic integrability means that the system is
completely integrable in the sens of the phase space being folited by tori,
which in addition are real parts of a complex algebraic tori (abelian
varieties). The method is devoted to illustrate how to decide about the a.c.i.
of hamiltonian systems and is applied to some examples. Finally, in section 4
we study an a.c.i. in the generalized sense which appears as covering of a.c.i.
system. The manifold invariant by the complex flow is covering of abelian
variety.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:16:27 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Lesfari",
"A.",
""
]
] |
0706.1580 | Paulo Lopes | P.A.A. Lopes (Instituto Nacional de Pesquisas Espaciais;
Harvard-Smithsonian Center for Astrophysics) | Empirical Photometric Redshifts of Luminous Red Galaxies and Clusters in
SDSS | 14 pages, 6 figures. Accepted to MNRAS. Minor changes in response to
referee report | MNRAS, 380:1608-1620, 2007 | 10.1111/j.1365-2966.2007.12203.x | null | astro-ph | null | In this work I discuss the necessary steps for deriving photometric redshifts
for luminous red galaxies (LRGs) and galaxy clusters through simple empirical
methods. The data used is from the Sloan Digital Sky Survey (SDSS). I show that
with three bands only ({\it gri}) it is possible to achieve results as accurate
as the ones obtained by other techniques, generally based on more filters. In
particular, the use of the $(g-i)$ color helps improving the final redshifts
(especially for clusters), as this color monotonically increases up to $z \sim
0.8$. For the LRGs I generate a catalog of $\sim 1.5$ million objects at $z <
0.70$. The accuracy of this catalog is $\sigma = 0.027$ for $z \le 0.55$ and
$\sigma = 0.049$ for $0.55 < z \le 0.70$. The photometric redshift technique
employed for clusters is independent of a cluster selection algorithm. Thus, it
can be applied to systems selected by any method or wavelength, as long as the
proper optical photometry is available. When comparing the redshift listed in
literature to the photometric estimate, the accuracy achieved for clusters is
$\sigma = 0.024$ for $z \le 0.30$ and $\sigma = 0.037$ for $030 < z \le 0.55$.
However, when considering the spectroscopic redshift as the mean value of SDSS
galaxies on each cluster region, the accuracy is at the same level as found by
other authors: $\sigma = 0.011$ for $z \le 0.30$ and $\sigma = 0.016$ for $030
< z \le 0.55$. The photometric redshift relation derived here is applied to
thousands of cluster candidates selected elsewhere. I have also used galaxy
photometric redshifts available in SDSS to identify groups in redshift space
and then compare the redshift peak of the nearest group to each cluster
redshift (ABRIDGED).
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:22:38 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Jul 2007 20:08:57 GMT"
}
] | 2009-02-10T00:00:00 | [
[
"Lopes",
"P. A. A.",
"",
"Instituto Nacional de Pesquisas Espaciais;\n Harvard-Smithsonian Center for Astrophysics"
]
] |
0706.1581 | Christopher Mooney | Christopher Mooney | Examples of Non-Rigid CAT(0) Groups from the Category of Knot Groups | 16 pages, 2 figures | Algebr. Geom. Topol. 8 (2008) 1667-1690 | 10.2140/agt.2008.8.1667 | null | math.GT math.GR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | C Croke and B Kleiner have constructed an example of a CAT(0) group with more
than one visual boundary. J Wilson has proven that this same group has
uncountably many distinct boundaries. In this article we prove that the knot
group of any connected sum of two non-trivial torus knots also has uncountably
many distinct CAT(0) boundaries.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:24:54 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Aug 2008 20:46:43 GMT"
}
] | 2016-01-20T00:00:00 | [
[
"Mooney",
"Christopher",
""
]
] |
0706.1582 | Christoph Gohle | Christoph Gohle, Bj\"orn Stein, Albert Schliesser, Thomas Udem and
Theodor W. H\"ansch | Cavity Enhanced Optical Vernier Spectroscopy, Broad Band, High
Resolution, High Sensitivity | 11 pages, 3 figures, submitted to PRL | PRL 99, 263902 (2007) | 10.1103/PhysRevLett.99.263902 | null | physics.optics physics.ins-det | null | A femtosecond frequency comb provides a vast number of equidistantly spaced
narrow band laser modes that can be simultaneously tuned and frequency
calibrated with 15 digits accuracy. Our Vernier spectrometer utilizes all of
theses modes in a massively parallel manner to rapidly record both absorption
and dispersion spectra with a sensitivity that is provided by a high finesse
broad band optical resonator and a resolution that is only limited by the
frequency comb line width while keeping the required setup simple.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:30:35 GMT"
}
] | 2017-09-06T00:00:00 | [
[
"Gohle",
"Christoph",
""
],
[
"Stein",
"Björn",
""
],
[
"Schliesser",
"Albert",
""
],
[
"Udem",
"Thomas",
""
],
[
"Hänsch",
"Theodor W.",
""
]
] |
0706.1583 | Armin Rest | A. Miceli, A. Rest, C. W. Stubbs, S. L. Hawley, K. H. Cook, E. A.
Magnier, K. Krisciunas, E. Bowell, B. Koehn | Evidence for Distinct Components of the Galactic Stellar Halo from 838
RR Lyrae Stars Discovered in the LONEOS-I Survey | 18 pages, 28 figures, apjemulated, minor corrections and
clarifications. Accepted to ApJ on Jan 21, 2008 | null | 10.1086/533484 | null | astro-ph | null | We present 838 ab-type RR Lyrae stars from the Lowell Observatory Near Earth
Objects Survey Phase I (LONEOS-I). These objects cover 1430 deg^2 and span
distances ranging from 3-30 kpc from the Galactic Center. Object selection is
based on phased, photometric data with 28-50 epochs. We use this large sample
to explore the bulk properties of the stellar halo, including the spatial
distribution. The period-amplitude distribution of this sample shows that the
majority of these RR Lyrae stars resemble Oosterhoff type I, but there is a
significant fraction (26 %) which have longer periods and appear to be
Oosterhoff type II. We find that the radial distributions of these two
populations have significantly different profiles (rho_{OoI} ~ R^(-2.26 +-
0.07) and rho_{OoII} ~ R^(-2.88 +- 0.11). This suggests that the stellar halo
was formed by at least two distinct accretion processes and supports dual-halo
models.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:46:25 GMT"
},
{
"version": "v2",
"created": "Tue, 5 Feb 2008 22:29:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Miceli",
"A.",
""
],
[
"Rest",
"A.",
""
],
[
"Stubbs",
"C. W.",
""
],
[
"Hawley",
"S. L.",
""
],
[
"Cook",
"K. H.",
""
],
[
"Magnier",
"E. A.",
""
],
[
"Krisciunas",
"K.",
""
],
[
"Bowell",
"E.",
""
],
[
"Koehn",
"B.",
""
]
] |
0706.1584 | M. Sultan Parvez | M. Sultan Parvez | On the theory of flat spacetime | 13 pages, 4 figures | null | null | null | physics.gen-ph | null | Special relativity turns out to be more than coordinate transformations in
which the constancy of the speed of light plays the central role between two
inertial reference frames. Special relativity, in essence, is a theory of
four-dimensional flat spacetime. Euclidian space spans three of the spacetime's
dimensions and time spans the fourth. Properties of light may not be needed to
describe spacetime, which exists independently of light. The article shows that
a theory of spacetime can be constructed from a geometric viewpoint in which
the speed of light does not play any role. Moreover postulating
four-dimensional geometry significantly simplifies the concept of special
relativity.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:40:29 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Parvez",
"M. Sultan",
""
]
] |
0706.1585 | Ana Dorotea Tarr\'io | A. M. Naveira, A. Tarrio | A method for the resolution of the Jacobi equation Y''+RY = 0 on the
manifold Sp(2)/SU(2) | 18 pages | null | null | null | math.DG | null | In this paper a method for the resolution of the differential equation of the
Jacobi vector fields in the manifold V1 = Sp(2)/SU(2) is exposed. These results
are applied to determine areas and volumes of geodesic spheres and balls.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 21:55:26 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Naveira",
"A. M.",
""
],
[
"Tarrio",
"A.",
""
]
] |
0706.1586 | R. F. Minchin | Robert Minchin (1 and 2), Jonathan Davies (2), Michael Disney (2),
Marco Grossi (2 and 3), Sabina Sabatini (4), Peter Boyce (2), Diego Garcia (2
and 5), Chris Impey (6), Christine Jordan (7), Robert Lang (2), Andrew Marble
(6), Sarah Roberts (2), Wim van Driel (8) ((1) Arecibo Observatory, (2)
Cardiff University, (3) Osservatorio Astrofisico di Arcetri, (4) Osservatorio
Astronomico di Roma, (5) University of Bonn, (6) Steward Observatory, (7)
Jodrell Bank Observatory, (8) Observatoire de Paris) | 21-cm synthesis observations of VIRGOHI 21 - a possible dark galaxy in
the Virgo Cluster | 8 pages, accepted to ApJ, uses emulateapj.cls. Mpeg animation (Fig.
2) available at ftp://ftp.naic.edu/pub/publications/minchin/video2.mpg | null | 10.1086/520620 | null | astro-ph | null | Many observations indicate that dark matter dominates the extra-galactic
Universe, yet no totally dark structure of galactic proportions has ever been
convincingly identified. Previously we have suggested that VIRGOHI 21, a 21-cm
source we found in the Virgo Cluster using Jodrell Bank, was a possible dark
galaxy because of its broad line-width (~200 km/s) unaccompanied by any visible
gravitational source to account for it. We have now imaged VIRGOHI 21 in the
neutral-hydrogen line and find what could be a dark, edge-on, spinning disk
with the mass and diameter of a typical spiral galaxy. Moreover, VIRGOHI 21 has
unquestionably been involved in an interaction with NGC 4254, a luminous spiral
with an odd one-armed morphology, but lacking the massive interactor normally
linked with such a feature. Numerical models of NGC 4254 call for a close
interaction ~10^8 years ago with a perturber of ~10^11 solar masses. This we
take as additional evidence for the massive nature of VIRGOHI 21 as there does
not appear to be any other viable candidate. We have also used the Hubble Space
Telescope to search for stars associated with the HI and find none down to an I
band surface brightness limit of 31.1 +/- 0.2 mag/sq. arcsec.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 22:25:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Minchin",
"Robert",
"",
"1 and 2"
],
[
"Davies",
"Jonathan",
"",
"2 and 3"
],
[
"Disney",
"Michael",
"",
"2 and 3"
],
[
"Grossi",
"Marco",
"",
"2 and 3"
],
[
"Sabatini",
"Sabina",
"",
"2\n and 5"
],
[
"Boyce",
"Peter",
"",
"2\n and 5"
],
[
"Garcia",
"Diego",
"",
"2\n and 5"
],
[
"Impey",
"Chris",
""
],
[
"Jordan",
"Christine",
""
],
[
"Lang",
"Robert",
""
],
[
"Marble",
"Andrew",
""
],
[
"Roberts",
"Sarah",
""
],
[
"van Driel",
"Wim",
""
]
] |
0706.1587 | Vijayashankar Ramareddy | V. Ramareddy, G. Behinaein, I. Talukdar, P. Ahmadi, G. S. Summy | Resonances of the Quantum $\delta$-Kicked Accelerator | 4 pages, 4 figures | null | null | null | physics.atom-ph | null | We report the observation of high order resonances of the quantum
$\delta$-kicked accelerator using a BEC kicked by a standing wave of light. The
signature of these resonances is the existence of quantum accelerator modes.
For the first time quantum accelerator modes were seen near 1/4 and 1/3 of the
Talbot time. Using a BEC enabled us to study the detailed structure of the
modes and resonances which are related to the fractional Talbot effect. We
present a general theory for this system and apply it to predict the behavior
of the accelerator modes.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 22:07:15 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Ramareddy",
"V.",
""
],
[
"Behinaein",
"G.",
""
],
[
"Talukdar",
"I.",
""
],
[
"Ahmadi",
"P.",
""
],
[
"Summy",
"G. S.",
""
]
] |
0706.1588 | Animashree Anandkumar | Animashree Anandkumar, Lang Tong, Ananthram Swami | Detection of Gauss-Markov Random Fields with Nearest-Neighbor Dependency | Information Theory, IEEE Transactions | vol. 55, no. 2, Feb. 2009 | 10.1109/TIT.2008.2009855 | null | cs.IT math.IT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The problem of hypothesis testing against independence for a Gauss-Markov
random field (GMRF) is analyzed. Assuming an acyclic dependency graph, an
expression for the log-likelihood ratio of detection is derived. Assuming
random placement of nodes over a large region according to the Poisson or
uniform distribution and nearest-neighbor dependency graph, the error exponent
of the Neyman-Pearson detector is derived using large-deviations theory. The
error exponent is expressed as a dependency-graph functional and the limit is
evaluated through a special law of large numbers for stabilizing graph
functionals. The exponent is analyzed for different values of the variance
ratio and correlation. It is found that a more correlated GMRF has a higher
exponent at low values of the variance ratio whereas the situation is reversed
at high values of the variance ratio.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 22:28:21 GMT"
},
{
"version": "v2",
"created": "Tue, 8 Jun 2010 23:05:36 GMT"
}
] | 2016-11-15T00:00:00 | [
[
"Anandkumar",
"Animashree",
""
],
[
"Tong",
"Lang",
""
],
[
"Swami",
"Ananthram",
""
]
] |
0706.1589 | Li Yang | Li Yang, Cheol-Hwan Park, Young-Woo Son, Marvin L. Cohen, and Steven
G. Louie | Quasiparticle Energies and Band Gaps of Graphene Nanoribbons | 5 pages and 4 figures | Phys. Rev. Lett. 99, 186801 (2007) | null | null | cond-mat.mes-hall | null | We present calculations of the quasiparticle energies and band gaps of
graphene nanoribbons (GNRs) carried out using a first-principles many-electron
Green's function approach within the GW approximation. Because of the
quasi-one-dimension nature of a GNR, electron-electron interaction effects due
to the enhanced screened Coulomb interaction and confinement geometry greatly
influence the quasiparticle band gap. Compared with previous tight-binding and
density functional theory studies, our calculated quasiparticle band gaps show
significant self-energy corrections for both armchair and zigzag GNRs, in the
range of 0.5-3.0 eV for ribbons of width 2.4-0.4 nm. The quasiparticle band
gaps found here suggest that use of GNRs for electronic device components in
ambient conditions may be viable.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 22:21:36 GMT"
}
] | 2007-11-11T00:00:00 | [
[
"Yang",
"Li",
""
],
[
"Park",
"Cheol-Hwan",
""
],
[
"Son",
"Young-Woo",
""
],
[
"Cohen",
"Marvin L.",
""
],
[
"Louie",
"Steven G.",
""
]
] |
0706.1590 | Nguyen Tien Zung | Nguyen Tien Zung | Kolmogorov condition near hyperbolic singularities of integrable
Hamiltonian systems | revised version, 11p, accepted for publication in a sepecial volume
in Regular and Chaotic Dynamics in honor of Richard Cushman | null | null | null | math.DS | null | In this paper we show that, if an integrable Hamiltonian system admits a
nondegenerate hyperbolic singularity then it will satisfy the Kolmogorov
condegeneracy condition near that singularity (under a mild additional
condition, which is trivial if the singularity contains a fixed point)
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 22:25:49 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Aug 2007 17:11:13 GMT"
}
] | 2007-08-28T00:00:00 | [
[
"Zung",
"Nguyen Tien",
""
]
] |
0706.1591 | Cyrille Marquet | Cyrille Marquet | Hard diffraction and the Color Glass Condensate | 4 pages, 2 figures, Proceedings of the XVth International Workshop on
Deep Inelastic Scattering (DIS07), Munich, Germany, April 16-20 2007 | null | null | null | hep-ph | null | Following the Good-and-Walker picture, hard diffraction in the
high-energy/small-x limit of QCD can be described in terms of eigenstates of
the scattering matrix off a Color Glass Condensate. From the CGC non-linear
evolution equations, it is then possible to derive the behavior of diffractive
cross-sections at small $x.$ I discuss recent results, in particular the
consequences of the inclusion of Pomeron loops in the evolution.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 22:38:17 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Marquet",
"Cyrille",
""
]
] |
0706.1592 | Francisco Cutanda-Henriquez | Francisco Cutanda-Henriquez, Silvia Vargas-Castrillon | A novel method for the evaluation of uncertainty in dose volume
histogram computation | 17 pages, 10 figures, 5 tables. Submitted | null | null | null | physics.med-ph | null | Dose volume histograms are a useful tool in state-of-the-art radiotherapy
planning, and it is essential to be aware of their limitations. Dose
distributions computed by treatment planning systems are affected by several
sources of uncertainty such as algorithm limitations, measurement uncertainty
in the data used to model the beam and residual differences between measured
and computed dose, once the model is optimized. In order to take into account
the effect of uncertainty, a probabilistic approach is proposed and a new kind
of histogram, a dose-expected volume histogram, is introduced. The expected
value of the volume in the region of interest receiving an absorbed dose equal
or greater than a certain value is found using the probability distribution of
the dose at each point. A rectangular probability distribution is assumed for
this point dose, and a relationship is given for practical computations. This
method is applied to a set of dose volume histograms for different regions of
interest for 6 brain patients, 8 lung patients, 8 pelvis patients and 6
prostate patients planned for IMRT. These results show how dose computation
uncertainty has effects on PTV coverage and, to a lesser extent, in dose to
organs at risk. This method allows to quantify these effects.
| [
{
"version": "v1",
"created": "Mon, 11 Jun 2007 23:12:49 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Cutanda-Henriquez",
"Francisco",
""
],
[
"Vargas-Castrillon",
"Silvia",
""
]
] |
0706.1593 | Erik Tago | E. Tago, J. Einasto, E. Saar, E. Tempel, M. Einasto, J. Vennik and V.
M\"uller | Groups of galaxies in the SDSS Data Release 5. A group-finder and a
catalogue | 11 pages, 15 figures, submitted to Astronomy and Astrophysics | Astron.Astrophys.479:927-937,2008 | 10.1051/0004-6361:20078036 | null | astro-ph | null | We extract groups of galaxies from the SDSS Data Release 5 with the purpose
of studying the supercluster-void network and environmental properties of
groups therein. We use a modified friends-of-friends (FoF) method with adopted
variable linking length in transverse and radial direction to eliminate
selection effects and to find reliably as many groups as possible to track the
supercluster network. We take into account various selection effects due to the
use of a magnitude limited sample. To determine linking length scaling we study
the luminosity-density relation in observed groups. We follow the changes in
group sizes and mean galaxy number densities within groups when shifting nearby
groups to larger distances. As a result we show that the linking length should
be a slowly growing function with distance. Our final sample contains 17143
groups in the equatorial, and 33219 groups in the northern part of the DR5
survey with membership N_g >= 2. The group catalogue is available at our
web-site http://www.obs.ee/~erik/index.html.
Due to a narrow magnitude window in the SDSS the group catalogue based on
this survey has been obtained by moderately growing linking length scaling law
up to redshift z = 0.12. Above this redshift the scaling law turns down. In the
redshift range z=0.12 - 0.2 only the cores are detected. Along with applying
weights when calculating luminosities it is possible to use groups for
determination of the large-scale luminosity-density field.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 01:45:24 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Tago",
"E.",
""
],
[
"Einasto",
"J.",
""
],
[
"Saar",
"E.",
""
],
[
"Tempel",
"E.",
""
],
[
"Einasto",
"M.",
""
],
[
"Vennik",
"J.",
""
],
[
"Müller",
"V.",
""
]
] |
0706.1594 | Qi Zhang S. | Qi S. Zhang | A uniform Sobolev inequality under Ricci flow | An application to 3-d Ricci flow with surgery is added | null | null | null | math.DG | null | Let ${\bf M}$ be a compact Riemannian manifold and the metrics $g=g(t)$
evolve by the Ricci flow. We prove the following result. The Sobolev imbedding
by Aubin or Hebey, perturbed by a scalar curvature term and modulo sharpness of
constants, holds uniformly for $({\bf M}, g(t))$ for all time if the Ricci flow
exists for all time; and if the Ricci flow develops a singularity in finite
time, then the same Sobolev imbedding holds uniformly after a standard
normalization. As a consequence, long time non-collapsing results are derived,
which improve Perelman's local non-collapsing results. An application to 3-d
Ricci flow with surgery is also presented.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 00:26:18 GMT"
},
{
"version": "v2",
"created": "Wed, 15 Aug 2007 21:02:20 GMT"
},
{
"version": "v3",
"created": "Fri, 17 Aug 2007 22:01:32 GMT"
},
{
"version": "v4",
"created": "Wed, 29 Aug 2007 17:35:10 GMT"
}
] | 2007-08-29T00:00:00 | [
[
"Zhang",
"Qi S.",
""
]
] |
0706.1595 | Sergey Kuznetsov | Lev Titarchuk (GMU/NRL/GSFC), Sergey Kuznetsov (UCR/IKI, Russia),
Nikolai Shaposhnikov (USRA/GSFC) | Correlations between X-ray Spectral and Timing Characteristics in Cyg
X-2 | 7 pages, 4 figures, accepted for publication in ApJ (October 1, 2007,
v667n2 issue) | Astrophys.J.667:404-410,2007 | 10.1086/520759 | null | astro-ph | null | Correlations between the quasi-periodic oscillations (QPOs) and the spectral
power-law index have been reported for a number of black hole candidate sources
and for four neutron star (NS) sources, 4U 0614+09, 4U 1608-52, 4U 1728-34 and
Sco X-1. An examination of QPO frequencies and index relationship in Cyg X-2 is
reported herein. The RXTE spectrum of Cyg X-2 can be adequately represented by
a simple two-component model of Compton up-scattering with a soft photon
electron temperature of about 0.7 keV and an iron K-line. Inferred spectral
power-law index shows correlation with the low QPO frequencies. We find that
the Thomson optical depth of the Compton cloud (CC) tau, in framework of
spherical geometry, is in the range of ~4-6, which is consistent with the
neutron star's surface being obscured. The NS high frequency pulsations are
presumably suppressed as a result of photon scattering off CC electrons because
of such high values of tau. We also point out a number of similarities in terms
timing (presence of low and high frequency QPOs) and spectral (high CC optical
depth and low CC plasma temperature) appearances between Cyg X-2 and Sco X-1.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 03:36:53 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Titarchuk",
"Lev",
"",
"GMU/NRL/GSFC"
],
[
"Kuznetsov",
"Sergey",
"",
"UCR/IKI, Russia"
],
[
"Shaposhnikov",
"Nikolai",
"",
"USRA/GSFC"
]
] |
0706.1596 | Ikkoh Shimizu Mr | Ikkoh Shimizu, Masayuki Umemura, Atsunori Yonehara | Large-Scale Structure of Short-Lived Lyman\alpha Emitters | 5 pages, 4 figures, accepted for publication in MNRAS | null | 10.1111/j.1745-3933.2007.00346.x | null | astro-ph | null | Recently discovered large-scale structure of Ly\alpha Emitters (LAEs) raises
a novel challenge to the cold dark matter (CDM) cosmology. The structure is
extended over more than 50 Mpc at redshift z=3.1, and exhibits a considerably
weak angular correlation. Such properties of LAE distributions appear to be
incompatible with the standard biased galaxy formation scenario in the CDM
cosmology. In this paper, by considering the possibility that LAEs are
short-lived events, we attempt to build up the picture of LAEs concordant with
the CDM cosmology. We find that if the lifetime of LAEs is as short as (6.7 \pm
0.6) \times 10^7 yr, the distributions of simulated galaxies successfully match
the extension and morphology of large-scale structure of LAEs at z=3.1, and
also the weak angular correlation function. This result implies that LAEs at
z=3.1 do not necessarily reside in high density peaks, but tends to be located
in less dense regions, in a different way from the expectation by the standard
biased galaxy formation scenario. In addition, we make a prediction for the
angular correlation function of LAEs at redshifts higher than 3. It is found
that the prediction deviates from that by the standard biased galaxy formation
scenario even at redshifts 4 < z < 6.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 01:16:25 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Shimizu",
"Ikkoh",
""
],
[
"Umemura",
"Masayuki",
""
],
[
"Yonehara",
"Atsunori",
""
]
] |
0706.1597 | Michael Fuhrer | Sungjae Cho, Yung-Fu Chen, Michael S. Fuhrer | Graphene Spin Transistor | null | Applied Physics Letters 91, 123105 (2007) | 10.1063/1.2784934 | null | cond-mat.mes-hall | null | Graphitic nanostructures, e.g. carbon nanotubes (CNT) and graphene, have been
proposed as ideal materials for spin conduction[1-7]; they have long electronic
mean free paths[8] and small spin-orbit coupling[9], hence are expected to have
very long spin-scattering times. In addition, spin injection and detection in
graphene opens new opportunities to study exotic electronic states such as the
quantum Hall[10,11] and quantum spin Hall[9] states, and spin-polarized edge
states[12] in graphene ribbons. Here we perform the first non-local four-probe
experiments[13] on graphene contacted by ferromagnetic Permalloy electrodes. We
observe sharp switching and often sign-reversal of the non-local resistance at
the coercive field of the electrodes, indicating definitively the presence of a
spin current between injector and detector. The non-local resistance changes
magnitude and sign quasi-periodically with back-gate voltage, and
Fabry-Perot-like oscillations[6,14,15] are observed, consistent with
quantum-coherent transport. The non-local resistance signal can be observed up
to at least T = 300 K.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 01:18:01 GMT"
}
] | 2007-12-05T00:00:00 | [
[
"Cho",
"Sungjae",
""
],
[
"Chen",
"Yung-Fu",
""
],
[
"Fuhrer",
"Michael S.",
""
]
] |
0706.1598 | Song Wei | Wei Song, Nai-Le Liu, Zeng-Bing Chen | Bounds on the multipartite entanglement of superpositions | 4 pages, 2 figure. few typos corrected | Phys. Rev. A 76, 054303 (2007) | 10.1103/PhysRevA.76.054303 | null | quant-ph | null | We derive the lower and upper bounds on the entanglement of a given
multipartite superposition state in terms of the entanglement of the states
being superposed. The first entanglement measure we use is the geometric
measure, and the second is the q-squashed entanglement. These bounds allow us
to estimate the amount of the multipartite entanglement of superpositions. We
also show that two states of high fidelity to one another do not necessarily
have nearly the same q-squashed entanglement.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 01:26:48 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Jun 2007 04:40:15 GMT"
},
{
"version": "v3",
"created": "Thu, 30 Aug 2007 02:38:42 GMT"
},
{
"version": "v4",
"created": "Sat, 20 Oct 2007 05:54:52 GMT"
},
{
"version": "v5",
"created": "Sat, 24 Nov 2007 02:32:55 GMT"
}
] | 2007-11-24T00:00:00 | [
[
"Song",
"Wei",
""
],
[
"Liu",
"Nai-Le",
""
],
[
"Chen",
"Zeng-Bing",
""
]
] |
0706.1599 | Eduard Alexis Larranaga Rubio | Alexis Larranaga | Thermodynamic Interpretation of the Field Equations of BTZ Charged Black
Hole near the Horizon | 5 pages | NuovoCim.B123:227-231,2008 | 10.1393/ncb/i2008-10509-7 | null | gr-qc | null | As is already known, a spacetime horizon acts like a boundary of a thermal
system an we can associate with it notions as temperature and entropy.
Following the work of M. Akbar, in this paper we will show how it is possible
to interpret the field equation of a charged BTZ black hole near horizon as a
thermodynamic identity dE=TdS+PdA+PhidQ, where Phi is the electric potential
and Q is the electric charge of BTZ black hole. These results indicate that the
field equations for the charged BTZ black hole possess intrinsic thermodynamic
properties near horizon.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 01:31:40 GMT"
},
{
"version": "v2",
"created": "Tue, 10 Jul 2007 20:13:06 GMT"
},
{
"version": "v3",
"created": "Mon, 16 Jul 2007 13:29:42 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Larranaga",
"Alexis",
""
]
] |
0706.1600 | Michel Sorel | HARP Collaboration: M.G. Catanesi, et al | Measurement of the production of charged pions by protons on a tantalum
target | 49 pages, 31 figures. Version accepted for publication on Eur. Phys.
J. C | Eur.Phys.J.C51:787-824,2007 | 10.1140/epjc/s10052-007-0361-0 | null | hep-ex | null | A measurement of the double-differential cross-section for the production of
charged pions in proton--tantalum collisions emitted at large angles from the
incoming beam direction is presented. The data were taken in 2002 with the HARP
detector in the T9 beam line of the CERN PS. The pions were produced by proton
beams in a momentum range from 3 \GeVc to 12 \GeVc hitting a tantalum target
with a thickness of 5% of a nuclear interaction length. The angular and
momentum range covered by the experiment ($100 \MeVc \le p < 800 \MeVc$ and
$0.35 \rad \le \theta <2.15 \rad$) is of particular importance for the design
of a neutrino factory. The produced particles were detected using a
small-radius cylindrical time projection chamber (TPC) placed in a solenoidal
magnet. Track recognition, momentum determination and particle identification
were all performed based on the measurements made with the TPC. An elaborate
system of detectors in the beam line ensured the identification of the incident
particles. Results are shown for the double-differential cross-sections
${{\mathrm{d}^2 \sigma}} / {{\mathrm{d}p\mathrm{d}\theta}}$ at four incident
proton beam momenta (3 \GeVc, 5 \GeVc, 8 \GeVc and 12 \GeVc). In addition, the
pion yields within the acceptance of typical neutrino factory designs are shown
as a function of beam momentum. The measurement of these yields within a single
experiment eliminates most systematic errors in the comparison between rates at
different beam momenta and between positive and negative pion production.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 01:34:31 GMT"
}
] | 2012-08-03T00:00:00 | [
[
"HARP Collaboration",
"",
""
],
[
"Catanesi",
"M. G.",
""
]
] |
0706.1601 | Dagny Looper | Dagny L. Looper (Institute for Astronomy, UH), J. Davy Kirkpatrick
(IPAC/Caltech), Adam J. Burgasser (MIT) | Discovery of 11 New T Dwarfs in the Two Micron All-Sky Survey, Including
a Possible L/T Transition Binary | 45 pages, 9 figures, 9 tables. Published in AJ. Replacement: Fixed
typos in 3 tables (some reported photometry was from the 2MASS Working
Database instead of the 2MASS All Sky Catalog) and updated Fig. 5 | Astron.J.134:1162-1182,2007 | 10.1086/520645 | null | astro-ph | null | We present the discovery of 11 new T dwarfs, found during the course of a
photometric survey for mid-to-late T dwarfs in the 2MASS Point Source Catalog
and from a proper motion selected sample of ultracool dwarfs in the 2MASS
Working Database. Using the NASA Infrared Telescope Facility SpeX spectrograph,
we obtained low-resolution (R~150) spectroscopy, allowing us to derive
near-infrared spectral types of T2-T8. One of these new T dwarfs, 2MASS
J13243559+6358284, was also discovered independently by Metchev et al., in
prep. This object is spectroscopically peculiar and possibly a binary and/or
very young (<300 Myr). We specifically attempted to model the spectrum of this
source as a composite binary to reproduce its peculiar spectral
characteristics. The latest-type object in our sample is a T8 dwarf, 2MASS
J07290002-3954043, now one of the four latest-type T dwarfs known. All 11 T
dwarfs are nearby given their spectrophotometric distance estimates, with 1 T
dwarf within 10 pc and 8 additional T dwarfs within 25 pc, if single. These new
additions increase the 25 pc census of T dwarfs by ~14%. Their proximity offers
an excellent opportunity to probe for companions at closer separations than are
possible for more distant T dwarfs.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 01:41:23 GMT"
},
{
"version": "v2",
"created": "Sat, 4 Aug 2007 01:23:14 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Looper",
"Dagny L.",
"",
"Institute for Astronomy, UH"
],
[
"Kirkpatrick",
"J. Davy",
"",
"IPAC/Caltech"
],
[
"Burgasser",
"Adam J.",
"",
"MIT"
]
] |
0706.1602 | Paolo Ghiggini | Paolo Ghiggini, Ko Honda and Jeremy Van Horn-Morris | The vanishing of the contact invariant in the presence of torsion | 6 pages, 1 figure | null | null | null | math.GT | null | We prove that the Ozsvath-Szabo contact invariant of a closed contact
3-manifold with positive Giroux torsion vanishes.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 02:03:26 GMT"
},
{
"version": "v2",
"created": "Fri, 18 Jan 2008 00:58:03 GMT"
}
] | 2008-01-18T00:00:00 | [
[
"Ghiggini",
"Paolo",
""
],
[
"Honda",
"Ko",
""
],
[
"Van Horn-Morris",
"Jeremy",
""
]
] |
0706.1603 | Yuichi Hoshino | Yuichi Hoshino | Solutions of Bethe-Salpter equations in QED3 | 14 pages, Revtex4,two figures.Add explanation for the boundary
conditions in section II-A,Section II-B is modified.References added.Abstract
modified | null | null | null | hep-th | null | To understand the mechanism of the fermion pair and fermion-antifermion pair
condensation,the solutions of Bethe-Salpeter equation in QED$_{3}$ is
examined.In the ladder appoximation our solution for the axial-scalar is
consistent with Ward-Takahashi-identity for the axial vector currents.Since the
massless scalar-vector sector is described by a coupled integral equation,it is
difficult to solve explicitly.We approximate the equation for large and small
momentum region separately and convert them into differential equations in
position space.These equation can be solved easily.Boundary condition at the
origin leads the eigenvalue for dimensionless coupling constant
$\lambda=e^{2}/m$.There exists solutions for massless scalar-vector
fermion-antifermion (fa) system with discrete spectrum. In our approximation
massless-scalar-vector ff systemes does not seem to exist.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 02:05:47 GMT"
},
{
"version": "v2",
"created": "Fri, 29 Jun 2007 12:23:00 GMT"
},
{
"version": "v3",
"created": "Sun, 1 Jul 2007 00:25:39 GMT"
},
{
"version": "v4",
"created": "Thu, 5 Jul 2007 13:27:34 GMT"
},
{
"version": "v5",
"created": "Mon, 9 Jul 2007 19:48:28 GMT"
}
] | 2007-07-09T00:00:00 | [
[
"Hoshino",
"Yuichi",
""
]
] |
0706.1604 | Keisuke Izumi | Keisuke Izumi and Jiro Soda | Renormalized Newtonian Cosmic Evolution with Primordial Non-Gaussianity | 12 pages, 2 figures | Phys.Rev.D76:083517,2007 | 10.1103/PhysRevD.76.083517 | KUNS-2080 | astro-ph gr-qc hep-th | null | We study Newtonian cosmological perturbation theory from a field theoretical
point of view. We derive a path integral representation for the cosmological
evolution of stochastic fluctuations. Our main result is the closed form of the
generating functional valid for any initial statistics. Moreover, we extend the
renormalization group method proposed by Mataresse and Pietroni to the case of
primordial non-Gaussian density and velocity fluctuations. As an application,
we calculate the nonlinear propagator and examine how the non-Gaussianity
affects the memory of cosmic fields to their initial conditions. It turns out
that the non-Gaussianity affect the nonlinear propagator. In the case of
positive skewness, the onset of the nonlinearity is advanced with a given
comoving wavenumber. On the other hand, the negative skewness gives the
opposite result.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 03:17:02 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Jun 2007 08:44:42 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Izumi",
"Keisuke",
""
],
[
"Soda",
"Jiro",
""
]
] |
0706.1605 | Juhi Jang | Juhi Jang | Local Well-Posedness of Dynamics of Viscous Gaseous Stars | 49 pages | null | null | null | math.AP math-ph math.MP | null | We establish the local in time well-posedness of strong solutions to the
vacuum free boundary problem of the compressible Navier-Stokes-Poisson system
in the spherically symmetric and isentropic motion. Our result captures the
physical vacuum boundary behavior of the Lane-Emden star configurations for all
adiabatic exponents $\gamma>{6/5}$.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 03:53:12 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Jang",
"Juhi",
""
]
] |
0706.1606 | MingGuang Hu | Ming-Guang Hu, Jing-Ling Chen (Chern Institute, Nankai Univ.) | Quantum Dynamical Algebra SU(1,1) in One-Dimensional Exactly Solvable
Potentials | No figures, 9 Pages accepted by International Journal of Theoretical
Physics | Int. J. Theor. Phys. 46, 2119 (2007) | 10.1007/s10773-006-9333-7 | null | quant-ph | null | We mainly explore the linear algebraic structure like SU(2) or SU(1,1) of the
shift operators for some one-dimensional exactly solvable potentials in this
paper. During such process, a set of method based on original diagonalizing
technique is presented to construct those suitable operator elements, J0, J_\pm
that satisfy SU(2) or SU(1,1) algebra. At last, the similarity between radial
problem and one-dimensional potentials encourages us to deal with the radial
problem in the same way.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 05:01:50 GMT"
}
] | 2009-01-09T00:00:00 | [
[
"Hu",
"Ming-Guang",
"",
"Chern Institute, Nankai Univ."
],
[
"Chen",
"Jing-Ling",
"",
"Chern Institute, Nankai Univ."
]
] |
0706.1607 | Andres del Junco | Boris Begun, Andres del Junco | Partitions with independent iterates in random dynamical systems | null | null | null | null | math.DS math.AC math.AG math.AP | null | Consider an invertible measure-preserving transformation of a probability
space. A finite partition of the space is called weakly independent if there
are infinitely many images of this partition under powers of the transformation
that are jointly independent. Krengel proved that a transformation is weakly
mixing if and only if weakly independent partitions of the underlying space are
dense among all finite partitions. Using the tools developed in the later
papers of del Junco-Reinhold-Weiss and del Junco-Begun we obtain Krengel- type
results for weakly mixing random dynamical systems (or equivalently, skew
products that are relatively weakly mixing).
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 04:27:12 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Begun",
"Boris",
""
],
[
"del Junco",
"Andres",
""
]
] |
0706.1608 | Kathy-Anne Brickman | K.-A. Brickman, M.-S. Chang, M. Acton, A. Chew, D. Matsukevich, P. C.
Haljan, V. S. Bagnato, and C. Monroe | Magneto-optical Trapping of Cadmium | 8 pages, 11 figures | null | 10.1103/PhysRevA.76.043411 | null | physics.atom-ph | null | We report the laser-cooling and confinement of Cd atoms in a magneto-optical
trap, and characterize the loading process from the background Cd vapor. The
trapping laser drives the 1S0-1P1 transition at 229 nm in this two-electron
atom and also photoionizes atoms directly from the 1P1 state. This
photoionization overwhelms the other loss mechanisms and allows a direct
measurement of the photoionization cross section, which we measure to be
2(1)x10^(-16)cm^(2) from the 1P1 state. When combined with nearby laser-cooled
and trapped Cd^(+) ions, this apparatus could facilitate studies in ultracold
interactions between atoms and ions.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 05:33:50 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Brickman",
"K. -A.",
""
],
[
"Chang",
"M. -S.",
""
],
[
"Acton",
"M.",
""
],
[
"Chew",
"A.",
""
],
[
"Matsukevich",
"D.",
""
],
[
"Haljan",
"P. C.",
""
],
[
"Bagnato",
"V. S.",
""
],
[
"Monroe",
"C.",
""
]
] |
0706.1609 | Cenke Xu | Cenke Xu | Phase transitions in coupled two dimensional XY systems with spatial
anisotropy | 8 pages, 6 figures | null | null | null | cond-mat.str-el cond-mat.soft | null | We study phase transitions of coupled two dimensional XY systems with spatial
anisotropy and $U(1) \times \mathbb{Z}_2$ symmetry, motivated by spinless
bosonic atoms trapped in square optical lattice on the metastable first excited
$p-$level orbitals with anisotropic hopping amplitudes. The phase transitions
of the system are generally split into an Ising transition and an XY
transition, but the sequence and the nature of the transitions depend on the
ratio between the anisotropic couplings. In the isotropic limit the XY
variables are expected to be disordered before the Ising variables when thermal
or quantum fluctuations are turned on gradually. In the anisotropic limit with
zero perpendicular hoppings, the finite temperature transition is a
Kosterlitz-Thouless transition driven by proliferation of hybrid half vortices,
and the zero temperature quantum phase transition is split into a bond order
transition and a 3D XY transition, which can be driven by the condensation of
either single vortices or half vortices. After the condensation of half
vortices the resultant state is a Mott Insulator of paired bosons. A small
perpendicular hopping $J_b$ leads to a 2D Ising transition at low temperature
and a 2+1d quantum Ising transition with a small charging energy at zero
temperature. Global phase diagrams for both classical and quantum phase
transitions are drawn. The analytical results obtained in this work are
expected to be checked both numerically and experimentally.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 05:20:29 GMT"
},
{
"version": "v2",
"created": "Sun, 23 Sep 2007 22:30:36 GMT"
}
] | 2007-09-24T00:00:00 | [
[
"Xu",
"Cenke",
""
]
] |
0706.1610 | M Pattabiraman | R. Venkatesh, M. Pattabiraman, S. Angappane, G. Rangarajan, K.
Sethupathi, Jessy Karatha, M. Fecioru-Morariu, R. M. Ghadimi and G.
Guntherodt | Complex ferromagnetic state and magnetocaloric effect in single
crystalline Nd_{0.7}Sr_{0.3}MnO_{3} | Accepted for publication in Phys. Rev. B | null | 10.1103/PhysRevB.75.224415 | null | cond-mat.mtrl-sci | null | The magnetocaloric effect in single crystalline Nd_{0.7}Sr_{0.3}MnO_{3} is
investigated by measuring the field-induced adiabatic change in temperature
which reveals a single negative peak around 130 K well below the Curie
temperature (T_C=203 K). In order to understand this unusual magnetocaloric
effect, we invoke the reported {55}^Mn spin-echo nuclear magnetic resonance,
electron magnetic resonance and polarized Raman scattering measurements on
Nd_{0.7}Sr_{0.3}MnO_{3}. We show that this effect is a manifestation of a
competition between the double exchange mechanism and correlations arising from
coupled spin and lattice degrees of freedom which results in a complex
ferromagnetic state. The critical behavior of Nd_{0.7}Sr_{0.3}MnO_{3} near
Curie temperature is investigated to study the influence of the coupled degrees
of freedom. We find a complicated behavior at low fields in which the order of
the transition could not be fixed and a second-order-like behavior at high
fields.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 05:29:55 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Venkatesh",
"R.",
""
],
[
"Pattabiraman",
"M.",
""
],
[
"Angappane",
"S.",
""
],
[
"Rangarajan",
"G.",
""
],
[
"Sethupathi",
"K.",
""
],
[
"Karatha",
"Jessy",
""
],
[
"Fecioru-Morariu",
"M.",
""
],
[
"Ghadimi",
"R. M.",
""
],
[
"Guntherodt",
"G.",
""
]
] |
0706.1611 | Vladislav Volman | Vladislav Volman, Richard Gerkin, Pak-Ming Lau, Eshel Ben-Jacob, and
Guo-Qiang Bi | Calcium and synaptic dynamics underlying reverberatory activity in
neuronal networks | null | Physical Biology, vol.4, pp.91-103, 2007 | 10.1088/1478-3975/4/2/003 | null | q-bio.NC q-bio.PE | null | Persistent activity is postulated to drive neural network plasticity and
learning. To investigate its underlying cellular mechanisms, we developed a
biophysically tractable model that explains the emergence, sustenance, and
eventual termination of short-term persistent activity. Using the model, we
reproduced the features of reverberating activity that were observed in small
(50-100 cells) networks of cultured hippocampal neurons, such as the appearance
of polysynaptic current clusters, the typical inter-cluster intervals, the
typical duration of reverberation, and the response to changes in
extra-cellular ionic composition. The model relies on action
potential-triggered residual presynaptic calcium, which we suggest plays an
important role in sustaining reverberations. We show that reverberatory
activity is maintained by enhanced asynchronous transmitter release from
pre-synaptic terminals, which in itself depends on the dynamics of residual
presynaptic calcium. Hence, asynchronous release, rather than being a "synaptic
noise", can play an important role in network dynamics. Additionally, we found
that a fast timescale synaptic depression is responsible for oscillatory
network activation during reverberations, whereas the onset of a slow timescale
depression leads to the termination of reverberation. The simplicity of our
model enabled a number of predictions that were confirmed by additional
analyses of experimental manipulations.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 06:14:07 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Volman",
"Vladislav",
""
],
[
"Gerkin",
"Richard",
""
],
[
"Lau",
"Pak-Ming",
""
],
[
"Ben-Jacob",
"Eshel",
""
],
[
"Bi",
"Guo-Qiang",
""
]
] |
0706.1612 | Ryosuke Kadono | Ryosuke Kadono | Nonlocal effect on the magnetic penetration depth in multigapped
superconductors | 2 pages, 1 figures | null | null | null | cond-mat.supr-con | null | A brief discussion is given on the nonlocal effect in multigapped
superconductivity. It is pointed out that the effective magnetic penetration
depth at lower external fields may be reduced by the nonlocal effect associated
with the presence of small energy gap. A crude estimation of the effect in
double gap system is provided and compared with the data obtained by muSR in
MgB2.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 06:42:30 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Jul 2007 03:08:48 GMT"
}
] | 2007-07-24T00:00:00 | [
[
"Kadono",
"Ryosuke",
""
]
] |
0706.1613 | Yoshihide Yamada | Yoshihide Yamada | Supersymmetric Construction of three-dimensional isospectral systems | 12 pages,[ver2]minor change,references added | null | 10.1143/PTP.118.545 | null | quant-ph hep-th math-ph math.MP | null | Three-dimensional isospectral systems are constructed using the framework of
supersymmetric quantum mechanics. In case the supercharge of first order in
momentum is used, it is proved that the constructed systems reduce to a trivial
generalization of one-dimensional systems. In case the second order supercharge
is used, nontrivial three-dimensional isospectral systems are constructed.
| [
{
"version": "v1",
"created": "Tue, 12 Jun 2007 06:30:42 GMT"
},
{
"version": "v2",
"created": "Fri, 3 Aug 2007 09:04:22 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Yamada",
"Yoshihide",
""
]
] |
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