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list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0707.0230 | Matthew Peet | Matthew M. Peet, Antonis Papachristodoulou, and Sanjay Lall | Positive Forms and Stability of Linear Time-Delay Systems | journal version, 14 pages | null | null | null | math.DS math.OC | null | We consider the problem of constructing Lyapunov functions for linear
differential equations with delays. For such systems it is known that
exponential stability implies the existence of a positive Lyapunov function
which is quadratic on the space of continuous functions. We give an explicit
parametrization of a sequence of finite-dimensional subsets of the cone of
positive Lyapunov functions using positive semidefinite matrices. This allows
stability analysis of linear time-delay systems to be formulated as a
semidefinite program.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:01:18 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Peet",
"Matthew M.",
""
],
[
"Papachristodoulou",
"Antonis",
""
],
[
"Lall",
"Sanjay",
""
]
] |
0707.0231 | Andre Th\"uring | Andre Thuering, Harald Lueck, and Karsten Danzmann | Analysis of a four-mirror cavity enhanced Michelson interferometer | null | Phys.Rev.E72:066615,2005 | 10.1103/PhysRevE.72.066615 | null | physics.optics physics.ins-det | null | We investigate the shot noise limited sensitivity of a four-mirror cavity
enhanced Michelson interferometer. The intention of this interferometer
topology is the reduction of thermal lensing and the impact of the
interferometers contrast although transmissive optics are used with high
circulating powers. The analytical expressions describing the light fields and
the frequency response are derived. Although the parameter space has 11
dimensions, a detailed analysis of the resonance feature gives boundary
conditions allowing systematic parameter studies.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:01:55 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Thuering",
"Andre",
""
],
[
"Lueck",
"Harald",
""
],
[
"Danzmann",
"Karsten",
""
]
] |
0707.0232 | Oliver Buss | O. Buss, T. Leitner, L. Alvarez-Ruso, U. Mosel | The influence of the nuclear medium on inclusive electron and neutrino
scattering off nuclei | 6 pages, 3 figures | Phys.Rev.C76:035502,2007 | 10.1103/PhysRevC.76.035502 | null | nucl-th hep-ph | null | We present a model for inclusive electron and neutrino scattering off nuclei
paying special attention to the influence of in-medium effects on the
quasi-elastic scattering and pion-production mechanisms. Our results for
electron scattering off Oxygen are compared to experimental data at beam
energies ranging from 0.7-1.5 GeV. The good description of electron scattering
serves as a benchmark for neutrino scattering.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:04:04 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Buss",
"O.",
""
],
[
"Leitner",
"T.",
""
],
[
"Alvarez-Ruso",
"L.",
""
],
[
"Mosel",
"U.",
""
]
] |
0707.0233 | Maria Emilia Guimaraes | M. C. B. Abdalla (IFT/Unesp), M. E. X. Guimaraes (IF/Uff) and J. M.
Hoff da Silva (IFT/Unesp) | Towards an hybrid compactification with a scalar-tensor global cosmic
string | RevTex, 7 pages. New version to be published in the JCAP (2008) | null | 10.1088/1475-7516/2008/09/021 | null | hep-th gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive a solution of the gravitational equations which leads to a
braneworld scenario in six dimensions using a global cosmic string solution in
a low energy effective string theory framework. The final spacetime is composed
by one warped brane with $\mathbb{R}^{(3,1)}\times S^{1}$ topology and a power
law warp factor, and one noncompact extra dimension transverse to the brane. By
looking at the current experimental bounds, we find a range of parameters in
which, if the on-brane dimension has an acceptable size, it does not solve the
hierarchy problem. In another example this problem is smoothed by the
Brans-Dicke parameter.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:05:17 GMT"
},
{
"version": "v2",
"created": "Thu, 4 Sep 2008 11:10:47 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Abdalla",
"M. C. B.",
"",
"IFT/Unesp"
],
[
"Guimaraes",
"M. E. X.",
"",
"IF/Uff"
],
[
"da Silva",
"J. M. Hoff",
"",
"IFT/Unesp"
]
] |
0707.0234 | Ketan Rajawat | Ketan Rajawat and Adrish Banerjee | Selection Relaying at Low Signal to Noise Ratios | null | null | null | null | cs.IT math.IT | null | Performance of cooperative diversity schemes at Low Signal to Noise Ratios
(LSNR) was recently studied by Avestimehr et. al. [1] who emphasized the
importance of diversity gain over multiplexing gain at low SNRs. It has also
been pointed out that continuous energy transfer to the channel is necessary
for achieving the max-flow min-cut bound at LSNR. Motivated by this we propose
the use of Selection Decode and Forward (SDF) at LSNR and analyze its
performance in terms of the outage probability. We also propose an energy
optimization scheme which further brings down the outage probability.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:08:52 GMT"
}
] | 2007-07-13T00:00:00 | [
[
"Rajawat",
"Ketan",
""
],
[
"Banerjee",
"Adrish",
""
]
] |
0707.0235 | H Sharatchandra S | H.S.Sharatchandra | Evading divergences in quantum field theory | 6 pages | null | null | IMSc/2007/07/08 | hep-th | null | Explicit solution of a Green function in a non-renormalizable toy model
demonstrates that Green functions of the interacting theory fall off much
faster than at the tree level at large momenta. This suggests a method of
calculations in quantum field theory which is free of divergences.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:25:42 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Sharatchandra",
"H. S.",
""
]
] |
0707.0236 | Woowon Kang | H.C. Choi, W. Kang, S. Das Sarma, L.N. Pfeiffer, and K.W. West | Fractional Quantum Hall Effect in the Second Landau Level | 5 pages, 3 figures | Phys. Rev. B 77, 081301(R) (2008) | 10.1103/PhysRevB.77.081301 | null | cond-mat.mes-hall | null | We present activation gap measurements of the fractional quantum Hall effect
(FQHE) in the second Landau level. Signatures for 14 (5) distinct
incompressible FQHE states are seen in a high (low) mobility sample with the
enigmatic 5/2 even denominator FQHE having a large activation gap of $\sim$600
($\sim$300mK) in the high (low) mobility sample. Our measured large relative
gaps for 5/2, 7/3, and 8/3 FQHE indicate emergence of exotic FQHE correlations
in the second Ladau level, possibly quite different from the well-known lowest
Landau level Laughlin correlations. Our measured 5/2 gap is found to be in
reasonable agreement with the theoretical gap once finite width and disorder
broadening corrections are taken into account.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:28:05 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Jul 2007 04:16:20 GMT"
}
] | 2009-07-21T00:00:00 | [
[
"Choi",
"H. C.",
""
],
[
"Kang",
"W.",
""
],
[
"Sarma",
"S. Das",
""
],
[
"Pfeiffer",
"L. N.",
""
],
[
"West",
"K. W.",
""
]
] |
0707.0237 | Kannan Soundararajan | K. Soundararajan | The number of imaginary quadratic fields with a given class number | 6 pages; Version 2 has some light changes | null | null | null | math.NT | null | We investigate the number ${\Cal F}(h)$ of imaginary quadratic fields with
class number $h$. We establish an asymptotic formula for the average value of
${\Cal F}(h)$. We also establish a modest non-trivial upper bound for ${\Cal
F}(h)$ and give an application to a question of Rosen and Silverman on the odd
part of the class number. Finally, we speculate on the asymptotic nature of
${\Cal F}(h)$.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:58:05 GMT"
},
{
"version": "v2",
"created": "Tue, 14 Aug 2007 19:31:12 GMT"
}
] | 2007-08-14T00:00:00 | [
[
"Soundararajan",
"K.",
""
]
] |
0707.0238 | Ulrich Hohenester | Ulrich Hohenester, Asier Eiguren, Stefan Scheel, E. A. Hinds | Spin flip lifetimes in superconducting atom chips: BCS versus Eliashberg
theory | 10 pages, 4 figures | null | 10.1103/PhysRevA.76.033618 | null | cond-mat.supr-con | null | We investigate theoretically the magnetic spin-flip transitions of neutral
atoms trapped near a superconducting slab. Our calculations are based on a
quantum-theoretical treatment of electromagnetic radiation near dielectric and
metallic bodies. Specific results are given for rubidium atoms near a niobium
superconductor. At the low frequencies typical of the atomic transitions, we
find that BCS theory greatly overestimates coherence effects, which are much
less pronounced when quasiparticle lifetime effects are included through
Eliashberg theory. At 4.2 K, the typical atomic spin lifetime is found to be
larger than a thousand seconds, even for atom-superconductor distances of one
micrometer. This constitutes a large enhancement in comparison with normal
metals.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:31:53 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Hohenester",
"Ulrich",
""
],
[
"Eiguren",
"Asier",
""
],
[
"Scheel",
"Stefan",
""
],
[
"Hinds",
"E. A.",
""
]
] |
0707.0239 | Mu-Tao Wang | Yng-Ing Lee, Mu-Tao Wang | Hamiltonian Stationary Shrinkers and Expanders for Lagrangian Mean
Curvature Flows | 19 pages | null | null | null | math.DG | null | We construct examples of shrinkers and expanders for Lagrangian mean
curvature flows. These examples are Hamiltonian stationary and asymptotic to
the union of two Hamiltonian stationary cones found by Schoen and Wolfson. The
Schoen-Wolfson cones $C_{p,q}$ are obstructions to the existence problems of
special Lagrangians or Lagrangian minimal surfaces in the variational approach.
It is known that these cone singularities cannot be resolved by any smooth
oriented Lagrangian submanifolds. The shrinkers and expanders that we found can
be glued together to yield solutions of the Brakke motion-a weak formulation of
the mean curvature flow. For any coprime pair $(p,q)$ other than $(2,1)$, we
construct such a solution that resolves any single Schoen-Wolfson cone
$C_{p,q}$. This thus provides an evidence to Schoen-Wolfson's conjecture that
the $(2,1)$ cone is the only area-minimizing cone. Higher dimensional
generalizations are also obtained.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:38:01 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Lee",
"Yng-Ing",
""
],
[
"Wang",
"Mu-Tao",
""
]
] |
0707.0240 | Giuseppe Ruzzi | John E. Roberts, Giuseppe Ruzzi, Ezio Vasselli | A theory of bundles over posets | null | Adv. Math. 220 (2009), no. 1, 125--153 | 10.1016/j.aim.2008.08.004 | null | math.AT math-ph math.MP | null | In algebraic quantum field theory the spacetime manifold is replaced by a
suitable base for its topology ordered under inclusion. We explain how certain
topological invariants of the manifold can be computed in terms of the base
poset. We develop a theory of connections and curvature for bundles over posets
in search of a formulation of gauge theories in algebraic quantum field theory.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:39:11 GMT"
}
] | 2012-08-22T00:00:00 | [
[
"Roberts",
"John E.",
""
],
[
"Ruzzi",
"Giuseppe",
""
],
[
"Vasselli",
"Ezio",
""
]
] |
0707.0241 | David A. Weinberg | David A. Weinberg (Texas Tech University), Nicholas J. Willis
(Whitworth College) | Singular points of real quartic curves via computer algebra | 24 pages, http://www.math.ttu.edu/~weinberg/ | null | null | null | math.AG | null | There are thirteen types of singular points for irreducible real quartic
curves and seventeen types of singular points for reducible real quartic
curves. This classification is originally due to D.A. Gudkov. There are nine
types of singular points for irreducible complex quartic curves and ten types
of singular points for reducible complex quartic curves. We derive the complete
classification with proof by using the computer algebra system Maple. We
clarify that the classification is based on computing just enough of the
Puiseux expansion to separate the branches. Thus, the proof consists of a
sequence of large symbolic computations that can be done nicely using Maple.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:29:16 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Weinberg",
"David A.",
"",
"Texas Tech University"
],
[
"Willis",
"Nicholas J.",
"",
"Whitworth College"
]
] |
0707.0242 | Gonzalo Usaj | M. D. Nu\~nez Regueiro, P. S. Cornaglia, Gonzalo Usaj, and C. A.
Balseiro | Slave boson theory for transport through magnetic molecules with
vibronic states | 7 pages, 4 figures, to be published in PRB | Phys. Rev. B 76, 075425 (2007) | 10.1103/PhysRevB.76.075425 | null | cond-mat.str-el cond-mat.mes-hall | null | We study the electron transport through a magnetic molecular transistor in
the Kondo limit using the slave boson technique. We include the electron-phonon
coupling and analyze the cases where the spin of the molecule is either S=1/2
or S=1. We use the Schrieffer-Wolff transformation to write down a low energy
Hamiltonian for the system. In the presence of electron-phonon coupling, and
for $S\smeq1$, the resulting Kondo Hamiltonian has two active channels. At low
temperature, these two channels interfere destructively, leading to a zero
conductance.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:44:06 GMT"
}
] | 2008-01-23T00:00:00 | [
[
"Regueiro",
"M. D. Nuñez",
""
],
[
"Cornaglia",
"P. S.",
""
],
[
"Usaj",
"Gonzalo",
""
],
[
"Balseiro",
"C. A.",
""
]
] |
0707.0243 | Emery Sokatchev | J.M. Drummond, G.P. Korchemsky and E. Sokatchev | Conformal properties of four-gluon planar amplitudes and Wilson loops | 25 pages, 6 figures; v3: minor corrections, references added | null | 10.1016/j.nuclphysb.2007.11.041 | LAPTH-1192/07, LPT-Orsay-07-46 | hep-th hep-ph | null | We present further evidence for a dual conformal symmetry in the four-gluon
planar scattering amplitude in N=4 SYM. We show that all the momentum integrals
appearing in the perturbative on-shell calculations up to five loops are dual
to true conformal integrals, well defined off shell. Assuming that the complete
off-shell amplitude has this dual conformal symmetry and using the basic
properties of factorization of infrared divergences, we derive the special form
of the finite remainder previously found at weak coupling and recently
reproduced at strong coupling by AdS/CFT. We show that the same finite term
appears in a weak coupling calculation of a Wilson loop whose contour consists
of four light-like segments associated with the gluon momenta. We also
demonstrate that, due to the special form of the finite remainder, the
asymptotic Regge limit of the four-gluon amplitude coincides with the exact
expression evaluated for arbitrary values of the Mandelstam variables.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:08:53 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 16:31:19 GMT"
},
{
"version": "v3",
"created": "Wed, 9 Jan 2008 17:12:41 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Drummond",
"J. M.",
""
],
[
"Korchemsky",
"G. P.",
""
],
[
"Sokatchev",
"E.",
""
]
] |
0707.0244 | Stavros Papadakis | Jorge Neves and Stavros Argyrios Papadakis | A construction of numerical Campedelli Surfaces with \Z/6 torsion group | 33 pages | null | null | null | math.AG math.AC | null | We produce a family of numerical Campedelli surfaces with \Z/6 torsion by
constructing the (Gorenstein codimension 5) canonical ring of the \'{e}tale six
to one cover using serial unprojection. In Section 2 we develop the necessary
algebraic machinery. Section 3 contains the numerical Campedelli surface
construction, while Section 4 contains remarks and open questions.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:54:27 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Neves",
"Jorge",
""
],
[
"Papadakis",
"Stavros Argyrios",
""
]
] |
0707.0245 | Bard Ermentrout | G. Bard Ermentrout, Roberto F. Gal\'an Nathaniel N. Urban | Relating Neural Dynamics to Neural Coding | 10 pages, 3 figures | null | null | null | q-bio.NC | null | We demonstrate that two key theoretical objects used widely in Computational
Neuroscience, the phase-resetting curve (PRC) from dynamics and the spike
triggered average (STA) from statistical analysis, are closely related under a
wide range of stimulus conditions. We prove that the STA is proportional to the
derivative of the PRC. We compare these analytic results to numerical
calculations for the Hodgkin-Huxley neuron and we apply the method to neurons
in the olfactory bulb of mice. This observation allows us to relate the
stimulus-response properties of a neuron to its dynamics, bridging the gap
between dynamical and information theoretic approaches to understanding brain
computations and facilitating the interpretation of changes in channels and
other cellular properties as influencing the representation of stimuli.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:56:43 GMT"
},
{
"version": "v2",
"created": "Wed, 26 Sep 2007 18:49:49 GMT"
}
] | 2007-09-26T00:00:00 | [
[
"Ermentrout",
"G. Bard",
""
],
[
"Urban",
"Roberto F. Galán Nathaniel N.",
""
]
] |
0707.0246 | Christian Paroissin | Christian Paroissin (LMA - PAU) | A new graphical tool of outliers detection in regression models based on
recursive estimation | null | null | null | null | stat.ME | null | We present in this paper a new tool for outliers detection in the context of
multiple regression models. This graphical tool is based on recursive
estimation of the parameters. Simulations were carried out to illustrate the
performance of this graphical procedure. As a conclusion, this tool is applied
to real data containing outliers according to the classical available tools.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 14:58:54 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Paroissin",
"Christian",
"",
"LMA - PAU"
]
] |
0707.0247 | Alireza Haghpayma | Alireza Haghpayma | A dynamical study of the pentaquark Theta+ state | the paper has been withdrawn by the author due to crucial type errors | null | null | null | hep-ph | null | this paper has been withdrawn by the author due to crucial type errors
| [
{
"version": "v1",
"created": "Sun, 1 Jul 2007 09:00:19 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Jul 2007 06:51:04 GMT"
}
] | 2007-07-04T00:00:00 | [
[
"Haghpayma",
"Alireza",
""
]
] |
0707.0248 | Joan Josep Ferrando | Bartolom\'e Coll, Joan Josep Ferrando and Juan Antonio Morales | On Newtonian frames | 26 pages, 4 figures | Foundations of Physics 39, 1280-1295 (2009); Physical Review D 80,
064038 (2009) | null | null | gr-qc | null | In Newtonian space-time there exist four, and only four, causal classes of
frames. Natural frames allow to extend this result to coordinate systems, so
that coordinate systems may be also locally classified in four causal classes.
These causal classes admit simple geometric descriptions and physical
interpretations. For example, one can generate representatives of the four
causal classes by means of the {\em linear synchronization group}. Of
particular interest is the {\em local Solar time synchronization}, which
reveals the limits of the frequent use of the concept of `causally oriented
oordinate', such as that of `time-like coordinate'. Classical {\em positioning
systems}, based in sound or light signals, are, by themselves, interesting
examples of location systems, i.e. of physically constructible coordinate
systems. They show that one can locate events in Newtonian space-time {\em
without} any use of the concept of synchronization. In fact, the coordinate
systems associated to positioning systems, belong to all the classes but the
standard one, i.e. the one based in the simultaneity synchronization. The
relativistic analogs of these examples, emphasize the contrast between the four
Newtonian and the one hundred and ninety nine Lorentzian causal classes of
frames of classical and relativistic space-times, respectively.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:02:55 GMT"
}
] | 2010-01-26T00:00:00 | [
[
"Coll",
"Bartolomé",
""
],
[
"Ferrando",
"Joan Josep",
""
],
[
"Morales",
"Juan Antonio",
""
]
] |
0707.0249 | Hans-Joachim Drescher | H.-J. Drescher (Frankfurt Institute for Advanced Studies (FIAS)), Y.
Nara (Akita International University) | Eccentricity fluctuations from the Color Glass Condensate at RHIC and
LHC | 2 pages, 2 figures | Phys.Rev.C76:041903,2007 | 10.1103/PhysRevC.76.041903 | null | nucl-th | null | In this brief note, we determine the fluctuations of the initial eccentricity
in heavy-ion collisions caused by fluctuations of the nucleon configurations.
This is done via a Monte-Carlo implementation of a Color Glass Condensate
$k_t$-factorization approach. The eccentricity fluctuations are found to nearly
saturate elliptic flow fluctuations measured recently at RHIC. Extrapolations
to LHC energies are shown.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:09:19 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Drescher",
"H. -J.",
"",
"Frankfurt Institute for Advanced Studies"
],
[
"Nara",
"Y.",
"",
"Akita International University"
]
] |
0707.0250 | John R. Klein | John R. Klein and Bruce Williams | The refined transfer, bundle structures and algebraic K-theory | This version contains mostly minor revisions | null | 10.1112/jtopol/jtp010 | null | math.AT math.KT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give new homotopy theoretic criteria for deciding when a fibration with
homotopy finite fibers admits a reduction to a fiber bundle with compact
topological manifold fibers. The criteria lead to a new and unexpected result
about homeomorphism groups of manifolds. A tool used in the proof is a
surjective splitting of the assembly map for Waldhausen's functor A(X).
We also give concrete examples of fibrations having a reduction to a fiber
bundle with compact topological manifold fibers but which fail to admit a
compact fiber smoothing. The examples are detected by algebraic K-theory
invariants.
We consider a refinement of the Becker-Gottlieb transfer. We show that a
version of the axioms described by Becker and Schultz uniquely determines the
refined transfer for the class of fibrations admitting a reduction to a fiber
bundle with compact topological manifold fibers.
In an appendix, we sketch a theory of characteristic classes for fibrations.
The classes are primary obstructions to finding a compact fiber smoothing.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:10:06 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Jul 2007 13:29:11 GMT"
},
{
"version": "v3",
"created": "Thu, 9 Aug 2007 17:55:30 GMT"
},
{
"version": "v4",
"created": "Thu, 18 Dec 2008 17:05:25 GMT"
}
] | 2014-02-26T00:00:00 | [
[
"Klein",
"John R.",
""
],
[
"Williams",
"Bruce",
""
]
] |
0707.0251 | Stephen Griffeth | Stephen Griffeth | Orthogonal functions generalizing Jack polynomials | 21 pages; revised version contains a combinatorial description of the
set of submodules of each standard module; 2nd revision uses Clifford theory
to relate G(r,p,n) Cherednik algebra to that for G(r,1,n) | null | null | null | math.RT math.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The rational Cherednik algebra $\HH$ is a certain algebra of
differential-reflection operators attached to a complex reflection group $W$.
Each irreducible representation $S^\lambda$ of $W$ corresponds to a standard
module $M(\lambda)$ for $\HH$. This paper deals with the infinite family
$G(r,1,n)$ of complex reflection groups; our goal is to study the standard
modules using a commutative subalgebra $\ttt$ of $\HH$ discovered by Dunkl and
Opdam. In this case, the irreducible $W$-modules are indexed by certain
sequences $\lambda$ of partitions. We first show that $\ttt$ acts in an upper
triangular fashion on each standard module $M(\lambda)$, with eigenvalues
determined by the combinatorics of the set of standard tableaux on $\lambda$.
As a consequence, we construct a basis for $M(\lambda)$ consisting of
orthogonal functions on $\CC^n$ with values in the representation $S^\lambda$.
For $G(1,1,n)$ with $\lambda=(n)$ these functions are the non-symmetric Jack
polynomials. We use intertwining operators to deduce a norm formula for our
orthogonal functions and give an explicit combinatorial description of the
lattice of submodules of $M(\lambda)$ in the case in which the orthogonal
functions are all well-defined.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:36:40 GMT"
},
{
"version": "v2",
"created": "Tue, 20 May 2008 20:29:51 GMT"
},
{
"version": "v3",
"created": "Sun, 9 Nov 2008 21:03:59 GMT"
}
] | 2008-11-09T00:00:00 | [
[
"Griffeth",
"Stephen",
""
]
] |
0707.0252 | Stefan Popescu | Bernhard Rothenstein and Stefan Popescu | A generic rule that simplifies the derivation of the transformation
equations accounting for the properties of the photon | A generic rule to derive relativistic equations | null | null | null | physics.gen-ph | null | We show that the transformation equation for the tardyon velocity involves
two generic functions which in turn depend on the relative velocity of the
involved reference frames, on the tardyon velocity u and on the polar angle
which define the direction along which the tardyon moves. The same functions
are further involved in the transformation equations for the space-time
coordinates of the same event generated by a moving tardyon and for its
relativistic mass, momentum and energy. Taking the limits of these functions
for u approaching c we obtain exactly the transformation equations for the
space-time coordinates of the same event generated by a photon and for its
momentum and energy. The same procedure works also for the transition from a
plane acoustic wave to an electromagnetic wave.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:20:48 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Rothenstein",
"Bernhard",
""
],
[
"Popescu",
"Stefan",
""
]
] |
0707.0253 | Nikolai Zotov | S.P. Baranov (Lebedev Institute of Physics), N.P. Zotov (SINP, Moscow
State University) | Upsilonium polarization as a touchstone in understanding the proton
dynamics in QCD | 8 pages, 2 figures | JETP Lett.86:435-438,2007 | 10.1134/S0021364007190010 | null | hep-ph | null | In the framework of the k_t-factorization approach, the production of
$\Upsilon mesons at the Fermilab Tevatron and CERN LHC is considered, and the
predictions on the spin alignment parameter $\alpha$ are presented. We argue
that measuring the polarization of quarkonium states can serve as a crucial
test discriminating two competing theoretical approaches to parton dynamics in
QCD.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:22:15 GMT"
},
{
"version": "v2",
"created": "Tue, 10 Jul 2007 13:02:39 GMT"
}
] | 2009-02-18T00:00:00 | [
[
"Baranov",
"S. P.",
"",
"Lebedev Institute of Physics"
],
[
"Zotov",
"N. P.",
"",
"SINP, Moscow\n State University"
]
] |
0707.0254 | David Sanchez | David Sanchez, Kicheon Kang | On the validity and breakdown of the Onsager symmetry in mesoscopic
conductors interacting with environments | 4 pages, 4 figures; discussions clarified; published version | Phys. Rev. Lett. 100, 036806 (2008) | 10.1103/PhysRevLett.100.036806 | null | cond-mat.mes-hall | null | We investigate magnetic-field asymmetries in the linear transport of a
mesoscopic conductor interacting with its environment. Interestingly, we find
that the interaction between the two systems causes an asymmetry only when the
environment is out of equilibrium. We elucidate our general result with the
help of a quantum dot capacitively coupled to a quantum Hall conductor and
discuss the asymmetry dependence on the environment bias and induced dephasing.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:23:09 GMT"
},
{
"version": "v2",
"created": "Fri, 25 Jan 2008 12:19:24 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sanchez",
"David",
""
],
[
"Kang",
"Kicheon",
""
]
] |
0707.0255 | Ronald J. Allen | Ronald J. Allen | Station-Keeping Requirements for Constellations of Free-Flying
Collectors Used for Astronomical Imaging in Space | 13 pages, 6 figures, accepted 6/29/07 for the August 2007 issue of
PASP | PASP 119, 914-922 (2007) | 10.1086/521276 | STScI 1778 | astro-ph | null | The accuracy requirements on station-keeping for constellations of
free-flying collectors coupled as (future) imaging arrays in space for
astrophysics applications are examined. The basic imaging element of these
arrays is the two-element interferometer. Accurate knowledge of two quantities
is required: the \textit{projected baseline length}, which is the distance
between the two interferometer elements projected on the plane tranverse to the
line of sight to the target; and the \textit{optical path difference}, which is
the difference in the distances from that transverse plane to the beam
combiner. ``Rules-of-thumb'' are determined for the typical accuracy required
on these parameters. The requirement on the projected baseline length is a
\textit{knowledge} requirement and depends on the angular size of the targets
of interest; it is generally at a level of half a meter for typical stellar
targets, decreasing to perhaps a few centimeters only for the widest attainable
fields of view. The requirement on the optical path difference is a
\textit{control} requirement and is much tighter, depending on the bandwidth of
the signal; it is at a level of half a wavelength for narrow (few %) signal
bands, decreasing to $\approx 0.2 \lambda$ for the broadest bandwidths expected
to be useful. Translation of these requirements into engineering requirements
on station-keeping accuracy depends on the specific details of the collector
constellation geometry. Several examples are provided to guide future
application of the criteria presented here. Some implications for the design of
such collector constellations and for the methods used to transform the
information acquired into images are discussed.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:38:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Allen",
"Ronald J.",
""
]
] |
0707.0256 | Agustin Sabio Vera | Agustin Sabio Vera (1), Florian Schwennsen (2) ((1) CERN, (2) Hamburg
U) | BFKL Effects in Azimuthal Angle Correlations of Forward Jets | Presented at DIS 2007: 15th International Workshop on Deep-Inelastic
Scattering, Munich, Germany, 16-20 Apr 2007, 4 pages, 3 figures, LATEX | null | null | null | hep-ph | null | The azimuthal angle correlation of Mueller-Navelet jets at hadron colliders
is studied in the NLO BFKL formalism. We highlight the need of collinear
improvements in the kernel to obtain good convergence properties and we obtain
better fits for the Tevatron data than at LO accuracy. We also estimate these
correlations for larger rapidity differences available at the LHC.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:33:19 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Vera",
"Agustin Sabio",
""
],
[
"Schwennsen",
"Florian",
""
]
] |
0707.0257 | Emmanuel Gobet | Arnaud Gloter (LAMA), Emmanuel Gobet (LJK) | LAMN property for hidden processes: the case of integrated diffusions | null | Annales de l'Institut Henri Poincare (B) Probability and
Statistics 44, 1 (2008) 104-128 | 10.1214/07-AIHP111 | null | math.PR math.ST stat.TH | null | In this paper we prove the Local Asymptotic Mixed Normality (LAMN) property
for the statistical model given by the observation of local means of a
diffusion process $X$. Our data are given by $ \int_0^1 X_{\frac{s+i}{n}} \dd
\mu (s)$ for $i=0,...,n-1$ and the unknown parameter appears in the diffusion
coefficient of the process $X$ only. Although the data are nor Markovian
neither Gaussian we can write down, with help of Malliavin calculus, an
explicit expression for the log-likelihood of the model, and then study the
asymptotic expansion. We actually find that the asymptotic information of this
model is the same one as for a usual discrete sampling of $X$.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:36:19 GMT"
}
] | 2009-06-09T00:00:00 | [
[
"Gloter",
"Arnaud",
"",
"LAMA"
],
[
"Gobet",
"Emmanuel",
"",
"LJK"
]
] |
0707.0258 | Nan-Kuo Ho | Nan-Kuo Ho, Chiu-Chu Melissa Liu | Yang-Mills Connections On Orientable and Nonorientable Surfaces | 86 pages | Mem. Amer. Math. Soc. 202 (2009), no. 948, vii+98 pp. | null | null | math.SG math.DG | null | In math.SG/0605587, we studied Yang-Mills functional on the space of
connections on a principal G_R-bundle over a closed, connected, nonorientable
surface, where G_R is any compact connected Lie group. In this sequel, we
generalize the discussion in "The Yang-Mills equations over Riemann surfaces"
by Atiyah and Bott, and math.SG/0605587. We obtain explicit descriptions (as
representation varieties) of Morse strata of Yang-Mills functional on
orientable and nonorientable surfaces for non-unitary classical groups SO(n)
and Sp(n). It turns out to be quite different from the unitary case. we use
Laumon and Rapoport's method in "The Langlands lemma and the Betti numbers of
stacks of G-bundles on a curve" to invert the Atiyah-Bott recursion relation,
and write down explicit formulas of rational equivariant Poincar\'{e} series of
the semistable stratum of the space of holomorphic structures on a principal
$SO(n,\bC)$-bundle or a principal $Sp(n,\bC)$-bundle.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:44:48 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Jul 2007 14:30:53 GMT"
},
{
"version": "v3",
"created": "Fri, 9 May 2008 05:44:11 GMT"
}
] | 2009-12-05T00:00:00 | [
[
"Ho",
"Nan-Kuo",
""
],
[
"Liu",
"Chiu-Chu Melissa",
""
]
] |
0707.0259 | Xuhua He | Xuhua He | On the affineness of Deligne-Lusztig varieties | 14 pages | null | null | null | math.RT | null | We prove that the Deligne-Lusztig variety associated to minimal length
elements in any $\d$-conjugacy class of the Weyl group is affine, which was
conjectured by Orlik and Rapoport in \cite{OR}.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:45:18 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"He",
"Xuhua",
""
]
] |
0707.0260 | Sperello di Serego Alighieri | Sperello di Serego Alighieri and Alessandro Bressan | Near UV properties of Early-Type Galaxies at z~1 | 5 pages, 4 figures. To be published in the Proceedings of the
Conference on "Ultraviolet Properties of Evolved Stellar Populations", M.
Chavez & E. Bertone, eds | null | null | null | astro-ph | null | We have used spectral fits to SSP-based atmosphere models to derive an
estimate of the average stellar age for an almost complete sample of 15
Early-Type Galaxies (ETG) at 0.88<z<1.3. The results are in only partial
agreement with the age estimates previously obtained for the same objects from
an analysis of the M/L_B ratio, derived from the Fundamental Plane (FP)
parameters. In particular spectral fits seem to underestimate the age of the
most luminous ETG, and therefore do not reproduce the downsizing effect, which
is clear for the FP ages. We also analyse the relationship between the
spectral-fit ages and various near-UV spectral indices.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:56:58 GMT"
}
] | 2019-08-19T00:00:00 | [
[
"Alighieri",
"Sperello di Serego",
""
],
[
"Bressan",
"Alessandro",
""
]
] |
0707.0261 | Rainer J. Fries | Rainer J. Fries, S. Turbide, C. Gale and D. K. Srivastava | Photons and Dileptons at LHC | Contribution to "Heavy Ion Collisions at the LHC: Last Call for
Predictions", to appear in J. Phys. G; 2 pages, 2 figures | null | null | null | nucl-th | null | We discuss real and virtual photon sources in heavy ion collisions and
present results for dilepton yields in Pb+Pb collisions at the LHC at
intermediate and large transverse momentum p_T.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:06:33 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Fries",
"Rainer J.",
""
],
[
"Turbide",
"S.",
""
],
[
"Gale",
"C.",
""
],
[
"Srivastava",
"D. K.",
""
]
] |
0707.0262 | Bastian Kubis | Christoph Hanhart, Bastian Kubis, Jose R. Pelaez | Investigation of a0-f0 mixing | 15 pages, 9 figures; discussion extended, title changed, version
published in Phys. Rev. D | Phys.Rev.D76:074028,2007 | 10.1103/PhysRevD.76.074028 | FZJ-IKP-TH-2007-21, HISKP-TH-07/18 | hep-ph hep-ex nucl-th | null | We investigate the isospin-violating mixing of the light scalar mesons
a0(980) and f0(980) within the unitarized chiral approach. Isospin-violating
effects are considered to leading order in the quark mass differences and
electromagnetism. In this approach both mesons are generated through
meson-meson dynamics. Our results provide a description of the mixing
phenomenon within a framework consistent with chiral symmetry and unitarity,
where these resonances are not predominantly q q-bar states. Amongst the
possible experimental signals, we discuss observable consequences for the
reaction J/Psi -> phi pi0 eta in detail. In particular we demonstrate that the
effect of a0-f0 mixing is by far the most important isospin-breaking effect in
the resonance region and can indeed be extracted from experiment.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:11:11 GMT"
},
{
"version": "v2",
"created": "Wed, 24 Oct 2007 11:15:35 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hanhart",
"Christoph",
""
],
[
"Kubis",
"Bastian",
""
],
[
"Pelaez",
"Jose R.",
""
]
] |
0707.0263 | Stefano Villa | Stefano Villa | Review of Bu leptonic decays | Flavor Physics & CP Violation Conference, Bled, 2007 | ECONFC070512:014,2007 | null | fpcp07_314 | hep-ex | null | This paper reviews the status of searches and measurements of Bu leptonic
decays, concentrating on the most recent results obtained at B-factories. We
will describe studies of decays of the type B+ -> ell+ nu and B+ -> ell+ nu
gamma.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:11:32 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Villa",
"Stefano",
""
]
] |
0707.0264 | S. S. Komissarov | S. S. Komissarov, M. V. Barkov | Magnetar-energized supernova explosions and GRB-jets | accepted by MNRAS, additional simulations, expanded discussion | null | 10.1111/j.1365-2966.2007.12485.x | null | astro-ph | null | In this paper we report on the early evolution of core-collapse supernova
explosion following the birth of a magnetar with the dipolar magnetic field of
B=10^{15}G and the rotational period of 2ms, which was studied by means of
axisymmetric general relativistic MHD simulations. The numerical models exhibit
highly collimated magnetically-driven jets very early on. The jets are
super-Alfvenic but remain sub-fast until the end of the simulations (t=0.2s).
The power released in the jets is about 3x10^{50}erg/s which implies the
spin-down time of ~37s. The total rotational energy of the magnetar,
E~10^{52}erg, is sufficient to drive hypernova but it is not clear as to how
large a fraction of this energy can be transfered to the stellar envelope.
Given the observed propagation speed of the jets, v_p~0.17c, they are expected
to traverse the progenitor in few seconds and after this most of the released
rotational energy would be simply carried away by these jets into the
surrounding space. Our results provide the first more or less self-consistent
numerical model of a central engine capable of producing, in the supernova
setting and on a long-term basis, collimated jets with sufficient power to
explain long duration GRBs and their afterglows. Although the flow speed of our
jets is relatively low, v_j~0.5c$, the cooling of proto-neutron star will
eventually result in much higher magnetization of its magnetospheres and
ultra-relativistic asymptotic speeds of the jets. Given the relatively long
cooling time-scale we still expect the jets to be only weakly relativistic by
the time of break out. This leads to a model of GRB jets with systematic
longitudinal variation of Lorentz factor which may have specific observational
signatures both in the prompt and the afterglow emission.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:14:15 GMT"
},
{
"version": "v2",
"created": "Fri, 6 Jul 2007 11:15:27 GMT"
},
{
"version": "v3",
"created": "Sat, 22 Sep 2007 18:18:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Komissarov",
"S. S.",
""
],
[
"Barkov",
"M. V.",
""
]
] |
0707.0265 | Eduardo Ezequiel Ferrero | Ezequiel E. Ferrero (1), Sergio A. Cannas (1) ((1) Facultad de
Matem\'atica, Astronom\'ia y F\'isica, Universidad Nacional de C\'ordoba) | Long term ordering kinetics of the two dimensional q-state Potts model | 10 pages, 17 figures | Phys. Rev. E, 76, 031108 (2007) | 10.1103/PhysRevE.76.031108 | null | cond-mat.stat-mech | null | We studied the non-equilibrium dynamics of the q-state Potts model in the
square lattice, after a quench to sub-critical temperatures. By means of a
continuous time Monte Carlo algorithm (non-conserved order parameter dynamics)
we analyzed the long term behavior of the energy and relaxation time for a wide
range of quench temperatures and system sizes. For q>4 we found the existence
of different dynamical regimes, according to quench temperature range. At low
(but finite) temperatures and very long times the Lifshitz-Allen-Cahn domain
growth behavior is interrupted with finite probability when the system stuck in
highly symmetric non-equilibrium metastable states, which induce activation in
the domain growth, in agreement with early predictions of Lifshitz [JETP 42,
1354 (1962)]. Moreover, if the temperature is very low, the system always gets
stuck at short times in a highly disordered metastable states with finite life
time, which have been recently identified as glassy states. The finite size
scaling properties of the different relaxation times involved, as well as their
temperature dependency are analyzed in detail.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:00:48 GMT"
}
] | 2007-09-13T00:00:00 | [
[
"Ferrero",
"Ezequiel E.",
""
],
[
"Cannas",
"Sergio A.",
""
]
] |
0707.0266 | Gabriele De Chiara | D. Binosi, G. De Chiara, S. Montangero, A. Recati | Increasing entanglement through engineered disorder in the random Ising
chain | 4 pages, published version, a few typos corrected | Phys. Rev. B 76, 140405(R) (2007) | 10.1103/PhysRevB.76.140405 | ECT*-07-13 | cond-mat.other quant-ph | null | The ground state entanglement entropy between block of sites in the random
Ising chain is studied by means of the Von Neumann entropy. We show that in
presence of strong correlations between the disordered couplings and local
magnetic fields the entanglement increases and becomes larger than in the
ordered case. The different behavior with respect to the uncorrelated
disordered model is due to the drastic change of the ground state properties.
The same result holds also for the random 3-state quantum Potts model.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:38:34 GMT"
},
{
"version": "v2",
"created": "Mon, 5 Nov 2007 08:42:22 GMT"
}
] | 2009-04-16T00:00:00 | [
[
"Binosi",
"D.",
""
],
[
"De Chiara",
"G.",
""
],
[
"Montangero",
"S.",
""
],
[
"Recati",
"A.",
""
]
] |
0707.0267 | Andrew Neitzke | Murat Gunaydin, Andrew Neitzke, Boris Pioline, Andrew Waldron | Quantum Attractor Flows | 43 pages, 6 figures; v2: typos and references added; v3: published
version, minor changes | JHEP 0709:056,2007 | 10.1088/1126-6708/2007/09/056 | LPTENS-07-26 | hep-th gr-qc | null | Motivated by the interpretation of the Ooguri-Strominger-Vafa conjecture as a
holographic correspondence in the mini-superspace approximation, we study the
radial quantization of stationary, spherically symmetric black holes in four
dimensions. A key ingredient is the classical equivalence between the radial
evolution equation and geodesic motion of a fiducial particle on the moduli
space M^*_3 of the three-dimensional theory after reduction along the time
direction. In the case of N=2 supergravity, M^*_3 is a para-quaternionic-Kahler
manifold; in this case, we show that BPS black holes correspond to a particular
class of geodesics which lift holomorphically to the twistor space Z of M^*_3,
and identify Z as the BPS phase space. We give a natural quantization of the
BPS phase space in terms of the sheaf cohomology of Z, and compute the exact
wave function of a BPS black hole with fixed electric and magnetic charges in
this framework. We comment on the relation to the topological string amplitude,
extensions to N>2 supergravity theories, and applications to automorphic black
hole partition functions.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:44:29 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 20:45:14 GMT"
},
{
"version": "v3",
"created": "Sun, 23 Sep 2007 01:53:58 GMT"
}
] | 2011-02-09T00:00:00 | [
[
"Gunaydin",
"Murat",
""
],
[
"Neitzke",
"Andrew",
""
],
[
"Pioline",
"Boris",
""
],
[
"Waldron",
"Andrew",
""
]
] |
0707.0268 | Giuliano Scarcelli | Yanhua Shih | Quantum Imaging | IEEE review | null | null | null | quant-ph | null | One of the most surprising consequences of quantum mechanics is the
entanglement of two or more distant particles. Although questions regarding
fundamental issues of quantum theory still exist, quantum entanglement has
started to play important roles in practical engineering applications. Quantum
imaging is one of these exciting areas. Quantum imaging has demonstrated two
peculiar features: (1) reproducing "ghost" images in a "nonlocal" manner, and
(2) enhancing the spatial resolution of imaging beyond the diffraction limit.
In this article, we start with the review of classical imaging to establish the
basic concepts and formalisms of imaging. We then analyze two-photon imaging
with particular emphasis on the physics of spatial resolution enhancement and
the "ghost" imaging phenomenon.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 15:20:40 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Shih",
"Yanhua",
""
]
] |
0707.0269 | Saurabh Sharma | Saurabh Sharma, A. K. Pandey, D. K. Ojha, W. P. Chen, S. K. Ghosh, B.
C. Bhatt, Maheswar, G., Ram Sagar | Star formation in young star cluster NGC 1893 | Accepted for the publication in MNRAS, 21 pages, 26 figures, 10
tables | null | 10.1111/j.1365-2966.2007.12156.x | null | astro-ph | null | We present a comprehensive multi-wavelength study of the star-forming region
NGC 1893 to explore the effects of massive stars on low-mass star formation.
Using near-infrared colours, slitless spectroscopy and narrow-band $H\alpha$
photometry in the cluster region we have identified candidate young stellar
objects (YSOs) distributed in a pattern from the cluster to one of the nearby
nebulae Sim 129. The $V, (V-I)$ colour-magnitude diagram of the YSOs indicates
that majority of these objects have ages between 1 to 5 Myr. The spread in the
ages of the YSOs may indicate a non-coeval star formation in the cluster. The
slope of the KLF for the cluster is estimated to be $0.34\pm0.07$, which agrees
well with the average value ($\sim 0.4$) reported for young clusters. For the
entire observed mass range $0.6 < M/M_\odot \le 17.7$ the value of the slope of
the initial mass function, $`\Gamma$', comes out to be $-1.27\pm0.08$, which is
in agreement with the Salpeter value of -1.35 in the solar neighborhood.
However, the value of $`\Gamma$' for PMS phase stars (mass range $0.6 <
M/M_\odot \le 2.0$) is found to be $-0.88\pm0.09$ which is shallower than the
value ($-1.71\pm0.20$) obtained for MS stars having mass range $2.5 < M/M_\odot
\le 17.7$ indicating a break in the slope of the mass function at $\sim 2
M_\odot$. Estimated $`\Gamma$' values indicate an effect of mass segregation
for main-sequence stars, in the sense that massive stars are preferentially
located towards the cluster center. The estimated dynamical evolution time is
found to be greater than the age of the cluster, therefore the observed mass
segregation in the cluster may be the imprint of the star formation process.
There is evidence for triggered star formation in the region, which seems to
govern initial morphology of the cluster.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:46:00 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sharma",
"Saurabh",
""
],
[
"Pandey",
"A. K.",
""
],
[
"Ojha",
"D. K.",
""
],
[
"Chen",
"W. P.",
""
],
[
"Ghosh",
"S. K.",
""
],
[
"Bhatt",
"B. C.",
""
],
[
"Maheswar",
"",
""
],
[
"G.",
"",
""
],
[
"Sagar",
"Ram",
""
]
] |
0707.0270 | Eric Varoquaux | E. Varoquaux and G. Varoquaux | The Sagnac effect in superfluids | Letter to the Editors of Uspheki Fisiki Nauk - 4 pages | null | null | null | gr-qc cond-mat.other | null | We comment on the interpretation of absolute rotation measurements with
superfluids, which involve the Sagnac effect. This effect, first observed in
rotating optical interferometers, has now been seen in a host of different
physical systems, ranging from atomic clocks to electrons, neutrons, atomic
beams, ... We show that the time-honored explanation of this effect based on
general relativity provides a common explanation for all these systems,
including superfluids, in contradistinction with the views expressed in a
recent review article.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:46:52 GMT"
}
] | 2007-07-04T00:00:00 | [
[
"Varoquaux",
"E.",
""
],
[
"Varoquaux",
"G.",
""
]
] |
0707.0271 | Pavel Chigansky | Pavel Chigansky | Maximum Likelihood Estimator for Hidden Markov Models in continuous time | Warning: due to a flaw in the publishing process, some of the
references in the published version of the article are confused | Statistical Inference for Stochastic Processes, Volume 12, Number
2 / June, 2009, pp. 139-163 | 10.1007/s11203-008-9025-4 | null | math.PR math.ST stat.TH | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The paper studies large sample asymptotic properties of the Maximum
Likelihood Estimator (MLE) for the parameter of a continuous time Markov chain,
observed in white noise. Using the method of weak convergence of likelihoods
due to I.Ibragimov and R.Khasminskii, consistency, asymptotic normality and
convergence of moments are established for MLE under certain strong ergodicity
conditions of the chain.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:47:31 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Aug 2007 09:57:52 GMT"
},
{
"version": "v3",
"created": "Thu, 5 Jun 2008 07:53:13 GMT"
},
{
"version": "v4",
"created": "Thu, 18 Jun 2009 07:05:27 GMT"
}
] | 2009-06-18T00:00:00 | [
[
"Chigansky",
"Pavel",
""
]
] |
0707.0272 | Walid K. Abou Salem | Walid K. Abou Salem | Solitary wave dynamics in time-dependent potentials | 38 pages, some typos corrected, one reference added, one remark added | null | 10.1063/1.2837429 | null | math-ph math.MP | null | We rigorously study the long time dynamics of solitary wave solutions of the
nonlinear Schr\"odinger equation in {\it time-dependent} external potentials.
To set the stage, we first establish the well-posedness of the Cauchy problem
for a generalized nonautonomous nonlinear Schr\"odinger equation. We then show
that in the {\it space-adiabatic} regime where the external potential varies
slowly in space compared to the size of the soliton, the dynamics of the center
of the soliton is described by Hamilton's equations, plus terms due to
radiation damping. We finally remark on two physical applications of our
analysis. The first is adiabatic transportation of solitons, and the second is
Mathieu instability of trapped solitons due to time-periodic perturbations.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:53:08 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Jul 2007 16:28:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Salem",
"Walid K. Abou",
""
]
] |
0707.0273 | Viqar Husain | Viqar Husain, Jorma Louko, Oliver Winkler | Quantum gravity and the Coulomb potential | 10 pages, 5 figures. v2: Minor presentational changes. One data point
added in Table I | Phys.Rev.D76:084002,2007 | 10.1103/PhysRevD.76.084002 | null | gr-qc | null | We apply a singularity resolution technique utilized in loop quantum gravity
to the polymer representation of quantum mechanics on R with the singular
-1/|x| potential. On an equispaced lattice, the resulting eigenvalue problem is
identical to a finite difference approximation of the Schrodinger equation. We
find numerically that the antisymmetric sector has an energy spectrum that
converges to the usual Coulomb spectrum as the lattice spacing is reduced. For
the symmetric sector, in contrast, the effect of the lattice spacing is similar
to that of a continuum self-adjointness boundary condition at x=0, and its
effect on the ground state is significant even if the spacing is much below the
Bohr radius. Boundary conditions at the singularity thus have a significant
effect on the polymer quantization spectrum even after the singularity has been
regularized.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 16:54:36 GMT"
},
{
"version": "v2",
"created": "Thu, 4 Oct 2007 07:39:05 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Husain",
"Viqar",
""
],
[
"Louko",
"Jorma",
""
],
[
"Winkler",
"Oliver",
""
]
] |
0707.0274 | Arunava Roy | Marco Cavaglia, Arunava Roy | QCD and spin effects in black hole airshowers | 6 pages, 2 figures, accepted for publication in Physical Review D | Phys.Rev.D76:044005,2007 | 10.1103/PhysRevD.76.044005 | null | hep-ph astro-ph gr-qc hep-th | null | In models with large extra dimensions, black holes may be produced in
high-energy particle collisions. We revisit the physics of black hole formation
in extensive airshowers from ultrahigh-energy cosmic rays, focusing on
collisional QCD and black hole emissivity effects. New results for rotating
black holes are presented. Monte Carlo simulations show that QCD effects and
black hole spin produce no observable signatures in airshowers. These results
further confirm that the main characteristics of black hole-induced airshowers
do not depend on the fine details of micro black hole models.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:18:09 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Cavaglia",
"Marco",
""
],
[
"Roy",
"Arunava",
""
]
] |
0707.0275 | Wu-Ki Tung | Wu-Ki Tung, H.L. Lai, J. Pumplin, P. Nadolsky, and C.-P. Yuan | Global QCD Analysis and Collider Phenomenology--CTEQ | Contribution to the proceedings of the DIS2007 Workshop, Munich,
Germany, April, 2007 | null | null | null | hep-ph | null | An overview is given of recent progress on a variety of fronts in the global
QCD analysis of the parton structure of the nucleon and its implication for
collider phenomenology, carried out by various subgroups of the CTEQ
collaboration.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:22:56 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Tung",
"Wu-Ki",
""
],
[
"Lai",
"H. L.",
""
],
[
"Pumplin",
"J.",
""
],
[
"Nadolsky",
"P.",
""
],
[
"Yuan",
"C. -P.",
""
]
] |
0707.0276 | Zhong-Bo Kang | Zhong-Bo Kang and Jian-Wei Qiu | Transverse momentum broadening of vector bosons in heavy ion collisions
at the LHC | 2 pages, 2 figures. Contributed to Workshop on Heavy Ion Collisions
at the LHC: Last Call for Predictions, Geneva, Switzerland, 14 May - 8 Jun
2007 | null | null | null | hep-ph | null | We calculate in perturbative QCD the transverse momentum broadening of vector
bosons in heavy ion collisions at the Large Hadron Collider (LHC). We predict
transverse momentum broadening of $W/Z$ bosons constructed from their leptonic
decay channels, which should be a clean probe of initial-state medium effect.
We also predict the upper limit of transverse momentum broadening of J/$\psi$
and $\Upsilon$ production as a function of N$_{\rm part}$ at the LHC energy.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:24:08 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Kang",
"Zhong-Bo",
""
],
[
"Qiu",
"Jian-Wei",
""
]
] |
0707.0277 | Prof. Dr. Thomas Pruschke | Robert Peters, Thomas Pruschke | Magnetic phases in the correlated Kondo-lattice model | null | Phys. Rev. B 76, 245101 (2007) | 10.1103/PhysRevB.76.245101 | null | cond-mat.str-el | null | We study magnetic ordering of an extended Kondo-lattice model including an
additional on-site Coulomb interaction between the itinerant states. The model
is solved in the dynamical mean-field theory using Wilson's numerical
renormalization group approach as impurity solver. For a bipartite lattice we
find at half filling the expected antiferromagnetic phase. Upon doping this
phase is gradually suppressed and hints towards phase separation are observed.
For large doping the model exhibits ferromagnetism, the appearance of which can
at first sight be explained by Rudermann-Kittel-Kasuya-Yosida interaction.
However, for large values of the Kondo coupling $J$ significant differences to
a simple Rudermann-Kittel-Kasuya-Yosida picture can be found. We furthermore
observe signs of quantum critical points for antiferromagnetic Kondo coupling
between the local spins and band states.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:43:49 GMT"
}
] | 2009-08-20T00:00:00 | [
[
"Peters",
"Robert",
""
],
[
"Pruschke",
"Thomas",
""
]
] |
0707.0278 | Jian-Ge Zhou | Jian-Ge Zhou, Quinton L. Williams, Frank Hagelberg | Headgroup dimerization in methanethiol monolayers on the Au(111)
surface: a density functional theory study | 6 pages, 2 figures, submitted to Phys. Rev. B | null | 10.1103/PhysRevB.76.075408 | null | cond-mat.mtrl-sci | null | A long-standing controversy related to the dimer pattern formed by S atoms in
methanethiol ($CH_{3}SH$) on the Au(111) surface has been resolved using
density functional theory. For the first time, dimerization of methanethiol
adsorbates on the Au(111) surface is established by computational modeling. For
methylthiolate ($CH_{3}S$), it is shown that the S atoms do not dimerize at
high coverage but reveal a dimer pattern at intermediate coverage. Molecular
dynamics simulation at high coverage demonstrates that the observed dialkyl
disulfide species are formed during the desorption process, and thus are not
attached to the surface.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:42:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Zhou",
"Jian-Ge",
""
],
[
"Williams",
"Quinton L.",
""
],
[
"Hagelberg",
"Frank",
""
]
] |
0707.0279 | D. F. Mota | Tomi Koivisto, David F. Mota | Accelerating Cosmologies with an Anisotropic Equation of State | 5 pages, 4 figures. Further details on Bianchi models and several
explanations and references added | Astrophys.J.679:1-5,2008 | 10.1086/587451 | null | astro-ph gr-qc hep-ph | null | If the dark energy equation of state is anisotropic, the expansion rate of
the universe becomes direction-dependent at late times. We show that such
models are not only cosmologically viable but that they could explain some of
the observed anomalies in the CMB, and shed some light into the coincidence
problem. The possible anisotropy can then be constrained by studying its
effects on the luminosity distance-redshift relation inferred from several
observations. A vector field action for dark energy is also presented as an
example of such possibility.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:54:00 GMT"
},
{
"version": "v2",
"created": "Fri, 31 Aug 2007 13:59:14 GMT"
},
{
"version": "v3",
"created": "Mon, 7 Jan 2008 10:26:19 GMT"
}
] | 2010-11-11T00:00:00 | [
[
"Koivisto",
"Tomi",
""
],
[
"Mota",
"David F.",
""
]
] |
0707.0280 | Seunghun Lee | M. Matsuda, H. Ueda, A. Kikkawa, Y. Tanaka, K. Katsumata, Y. Narumi,
T. Inami, Y. Ueda, S.-H. Lee | Spin-lattice instability to a fractional magnetization state in the
spinel HgCr2O4 | null | Nature Physics Vol. 3, 397 (2007) | 10.1038/nphys586 | null | cond-mat.str-el | null | Magnetic systems are fertile ground for the emergence of exotic states when
the magnetic interactions cannot be satisfied simultaneously due to the
topology of the lattice - a situation known as geometrical frustration.
Spinels, AB2O4, can realize the most highly frustrated network of
corner-sharing tetrahedra. Several novel states have been discovered in
spinels, such as composite spin clusters and novel charge-ordered states. Here
we use neutron and synchrotron X-ray scattering to characterize the fractional
magnetization state of HgCr2O4 under an external magnetic field, H. When the
field is applied in its Neel ground state, a phase transition occurs at H ~ 10
Tesla at which each tetrahedron changes from a canted Neel state to a
fractional spin state with the total spin, Stet, of S/2 and the lattice
undergoes orthorhombic to cubic symmetry change. Our results provide the
microscopic one-to-one correspondence between the spin state and the lattice
distortion.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:47:56 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Matsuda",
"M.",
""
],
[
"Ueda",
"H.",
""
],
[
"Kikkawa",
"A.",
""
],
[
"Tanaka",
"Y.",
""
],
[
"Katsumata",
"K.",
""
],
[
"Narumi",
"Y.",
""
],
[
"Inami",
"T.",
""
],
[
"Ueda",
"Y.",
""
],
[
"Lee",
"S. -H.",
""
]
] |
0707.0281 | Manfred Hartl | Manfred Hartl | On Fox quotients of arbitrary group algebras | 44 pages; introduction and notation improved, some minor errors
corrected | Internat. J. Algebra Comput. 20 (5) (2010), 619-660 | null | LAMAV Preprint 07/01 | math.GR math.RA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For a group $G$, N-series $\cal G$ of $G$ and commutative ring $R$ let
$I^n_{R,\cal G}(G)$, $n\ge 0$, denote the filtration of the group algebra
$R(G)$ induced by $\cal G$, and $I_R(G)$ its augmentation ideal. For subgroups
$H$ of $G$, left ideals $J$ of $R(H)$ and right $H$-submodules $M$ of $I_Z(G)$
the quotients $I_R(G)J/MJ$ are studied by homological methods, notably for $M=
I_Z(G)I_Z(H)$, $I_Z(H)I_Z(G) + I_Z([H,G])Z(G)$ and $Z(G)I_Z(N) +I^n_{Z,\cal
G}(G)$ with $N \lhd G$ where the group $I_R(G)J/MJ$ is completely determined
for $n=2$. The groups $I^{n-1}_{Z,\cal G}(G)I_Z(H)/I^n_{Z,\cal G}(G)I_Z(H)$ are
studied and explicitly computed for $n\le 3$ in terms of enveloping rings of
certain graded Lie rings and of torsion products of abelian groups.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:58:03 GMT"
},
{
"version": "v2",
"created": "Fri, 9 Apr 2010 14:27:30 GMT"
}
] | 2011-07-12T00:00:00 | [
[
"Hartl",
"Manfred",
""
]
] |
0707.0282 | Igor Razgon | Igor Razgon and Barry O'Sullivan | Directed Feedback Vertex Set is Fixed-Parameter Tractable | 14 pages | null | null | null | cs.DS cs.CC | null | We resolve positively a long standing open question regarding the
fixed-parameter tractability of the parameterized Directed Feedback Vertex Set
problem. In particular, we propose an algorithm which solves this problem in
$O(8^kk!*poly(n))$.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 17:56:53 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Razgon",
"Igor",
""
],
[
"O'Sullivan",
"Barry",
""
]
] |
0707.0283 | Alvaro de Rujula | A. De Rujula | What SWIFT has taught us about X-ray flashes and long-duration gamma-ray
bursts | A talk at the 2007 Frascati Workshop, Vulcano, Italy. 12 pages total,
17 figures | null | null | null | astro-ph hep-ph | null | Recent data gathered and triggered by the SWIFT satellite have greatly
improved our knowledge of long-duration gamma ray bursts (GRBs) and X-ray
flashes (XRFs). This is particularly the case for the X-ray data at all times,
and for UV and optical data at very early times. I show that the optical and
X-ray observations are in excellent agreement with the predictions of the
"cannonball" model of GRBs and XRFs. Elementary physics and just two mechanisms
underlie these predictions: inverse Compton scattering and synchrotron
radiation, generally dominant at early and late times, respectively. I put this
result in its proper context and dedicate the paper to those who planed, built
and operate SWIFT, a true flying jewel.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:04:13 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"De Rujula",
"A.",
""
]
] |
0707.0284 | Xinjia Chen | Xinjia Chen, Guoxiang Gu and Kemin Zhou | A statistical theory for the measurement and estimation of Rayleigh
fading channel | 25 pages, 10 figures | null | null | null | math.ST math.PR stat.AP stat.TH | null | In this paper, we propose a statistical theory on measurement and estimation
of Rayleigh fading channels in wireless communications and provide complete
solutions to the fundamental problems: What is the optimum estimator for the
statistical parameters associated with the Rayleigh fading channel, and how
many measurements are sufficient to estimate these parameters with the
prescribed margin of error and confidence level? Our proposed statistical
theory suggests that two testing signals of different strength be used. The
maximum likelihood (ML) estimator is obtained for estimation of the statistical
parameters of the Rayleigh fading channel that is both sufficient and complete
statistic. Moreover, the ML estimator is the minimum variance (MV) estimator
that in fact achieves the Cramer-Rao lower bound.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:04:35 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Chen",
"Xinjia",
""
],
[
"Gu",
"Guoxiang",
""
],
[
"Zhou",
"Kemin",
""
]
] |
0707.0285 | Edwin Hammerich | Edwin Hammerich | A Generalized Sampling Theorem for Frequency Localized Signals | 20 pages, extended version of talk at International Workshop on
Sampling Theory and Applications SampTA07, Thessaloniki, Greece, June 1-5,
2007. Submitted to Sampl. Theory Signal Image Process | Sampl. Theory Signal Image Process., Vol. 8, No. 2, May 2009, pp.
127-146 | null | null | cs.IT math.IT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A generalized sampling theorem for frequency localized signals is presented.
The generalization in the proposed model of sampling is twofold: (1) It applies
to various prefilters effecting a "soft" bandlimitation, (2) an approximate
reconstruction from sample values rather than a perfect one is obtained (though
the former might be "practically perfect" in many cases). For an arbitrary
finite-energy signal the frequency localization is performed by a prefilter
realizing a crosscorrelation with a function of prescribed properties. The
range of the filter, the so-called localization space, is described in some
detail. Regular sampling is applied and a reconstruction formula is given. For
the reconstruction error a general error estimate is derived and connections
between a critical sampling interval and notions of "soft bandwidth" for the
prefilter are indicated. Examples based on the sinc-function, Gaussian
functions and B-splines are discussed.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:40:29 GMT"
},
{
"version": "v2",
"created": "Wed, 15 Apr 2009 19:48:31 GMT"
}
] | 2009-08-30T00:00:00 | [
[
"Hammerich",
"Edwin",
""
]
] |
0707.0286 | Manfred Hartl | Manfred Hartl | The relative second Fox and third dimension subgroup of arbitrary groups | 17 pages | Indian J. Pure Appl. Math. 39 (5) (2008), 435-451 | null | LAMAV Preprint 07.02 | math.GR math.RA | null | Let $I_R(G)$ denote the augmentation ideal of the group algebra $R(G)$ of a
group $G$ with coefficients in a commutative ring $R$. We give a complete
description of the third relative dimension subgroup
$G\cap(1+I_R(K)I_R(G)+I^3_R(G))$ and the second relative Fox subgroup
$G\cap(1+I_R(K)I_R(H)+I^2_R(G)I_R(H))$ for any subgroups $K$ and $H$ of $G$.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:41:33 GMT"
}
] | 2011-07-12T00:00:00 | [
[
"Hartl",
"Manfred",
""
]
] |
0707.0287 | Daniel Welty | Daniel E. Welty (Univ. of Chicago) | Monitoring the Variable Interstellar Absorption toward HD 219188 with
HST/STIS | 33 pages, 6 figures, aastex, accepted to ApJ | null | 10.1086/521269 | null | astro-ph | null | We discuss the results of continued spectroscopic monitoring of the variable
intermediate-velocity (IV) absorption at v = -38 km/s toward HD 219188. After
reaching maxima in mid-2000, the column densities of both Na I and Ca II in
that IV component declined by factors >= 2 by the end of 2006. Comparisons
between HST/STIS echelle spectra obtained in 2001, 2003, and 2004 and HST/GHRS
echelle spectra obtained in 1994--1995 indicate the following: (1) The
absorption from the dominant species S II, O I, Si II, and Fe II is roughly
constant in all four sets of spectra -- suggesting that the total N(H) and the
(mild) depletions have not changed significantly over a period of nearly ten
years. (2) The column densities of the trace species C I (both ground and
excited fine-structure states) and of the excited state C II* all increased by
factors of 2--5 between 1995 and 2001 -- implying increases in the hydrogen
density n_H (from about 20 cm^{-3} to about 45 cm^{-3}) and in the electron
density n_e (by a factor >= 3) over that 6-year period. (3) The column
densities of C I and C II* -- and the corresponding inferred n_H and n_e --
then decreased slightly between 2001 and 2004. (4) The changes in C I and C II*
are very similar to those seen for Na I and Ca II. The relatively low total
N(H) and the modest n_H suggest that the -38 km/s cloud toward HD 219188 is not
a very dense knot or filament. Partial ionization of hydrogen appears to be
responsible for the enhanced abundances of Na I, C I, Ca II, and C II*. In this
case, the variations in those species appear to reflect differences in density
and ionization [and not N(H)] over scales of tens of AU.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:43:43 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Welty",
"Daniel E.",
"",
"Univ. of Chicago"
]
] |
0707.0288 | Mattia Righi | Mattia Righi, Carlos Hernandez-Monteagudo, Rashid Sunyaev | The clustering of merging star-forming haloes: dust emission as high
frequency arcminute CMB foreground | 18 pages, 16 figures. Accepted by Astronomy & Astrophysics | Nuovo Cim.B122:1463-1466,2007 | 10.1393/ncb/i2008-10490-1 | null | astro-ph | null | Future observations of CMB anisotropies will be able to probe high multipole
regions of the angular power spectrum, corresponding to a resolution of a few
arcminutes. Dust emission from merging haloes is one of the foregrounds that
will affect such very small scales. We estimate the contribution to CMB angular
fluctuations from objects that are bright in the sub-millimeter band due to
intense star formation bursts following merging episodes. We base our approach
on the Lacey-Cole merger model and on the Kennicutt relation which connects the
star formation rate in galaxies with their infrared luminosity. We set the free
parameters of the model in order to not exceed the SCUBA source counts, the
Madau plot of star formation rate in the universe and COBE/FIRAS data on the
intensity of the sub-millimeter cosmic background radiation. We show that the
angular power spectrum arising from the distribution of such star-forming
haloes will be one of the most significant foregrounds in the high frequency
channels of future CMB experiments, such as PLANCK, ACT and SPT. The
correlation term, due to the clustering of multiple haloes at redshift z~2-6,
is dominant in the broad range of angular scales 200<l<3000. Poisson
fluctuations due to bright sub-millimeter sources are more important at higher
l, but since they are generated from the bright sources, such contribution
could be strongly reduced if bright sources are excised from the sky maps. The
contribution of the correlation term to the angular power spectrum depends
strongly on the redshift evolution of the escape fraction of UV photons and the
resulting temperature of the dust. The measurement of this signal will
therefore give important information about galaxies in the early stage of their
evolution.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:44:20 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Nov 2007 13:11:36 GMT"
}
] | 2010-11-11T00:00:00 | [
[
"Righi",
"Mattia",
""
],
[
"Hernandez-Monteagudo",
"Carlos",
""
],
[
"Sunyaev",
"Rashid",
""
]
] |
0707.0289 | Prof. Dr. Thomas Pruschke | Riccardo Gezzi, Andreas Dirks, Thomas Pruschke | Transport through single-level quantum dot in a magnetic field | null | null | null | null | cond-mat.mes-hall | null | We study the effect of an external magnetic field on the transport properties
of a quantum dot using a recently developed extension of the functional
renormalization group approach to non-equilibrium situations. We discuss in
particular the interplay and competition of the different energy scales of the
dot and the magnetic field on the stationary non-equilibrium current and
conductance. As rather interesting behavior we find a switching behavior of the
magnetic field for intermediate correlations and bias voltage.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 18:48:34 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Jul 2007 10:50:49 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Gezzi",
"Riccardo",
""
],
[
"Dirks",
"Andreas",
""
],
[
"Pruschke",
"Thomas",
""
]
] |
0707.0290 | Huaiyu Duan | Huaiyu Duan (UCSD), George M. Fuller (UCSD), J. Carlson (LANL) and
Yong-Zhong Qian (UMN) | Neutrino Mass Hierarchy and Stepwise Spectral Swapping of Supernova
Neutrino Flavors | 4 pages, 2 figures. Version accepted by PRL | Phys.Rev.Lett.99:241802,2007 | 10.1103/PhysRevLett.99.241802 | null | astro-ph hep-ph | null | We examine a phenomenon recently predicted by numerical simulations of
supernova neutrino flavor evolution: the swapping of supernova $\nu_e$ and
$\nu_{\mu,\tau}$ energy spectra below (above) energy $\EC$ for the normal
(inverted) neutrino mass hierarchy. We present the results of large-scale
numerical calculations which show that in the normal neutrino mass hierarchy
case, $\EC$ decreases as the assumed $\nu_e\rightleftharpoons\nu_{\mu,\tau}$
effective $2\times 2$ vacuum mixing angle ($\simeq \theta_{1 3}$) is decreased.
However, these calculations also indicate that $\EC$ is essentially independent
of the vacuum mixing angle in the inverted neutrino mass hierarchy case. With a
good neutrino signal from a future Galactic supernova, the above results could
be used to determine the neutrino mass hierarchy even if $\theta_{13}$ is too
small to be detected in terrestrial neutrino oscillation experiments.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:04:25 GMT"
},
{
"version": "v2",
"created": "Fri, 14 Dec 2007 18:32:07 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Duan",
"Huaiyu",
"",
"UCSD"
],
[
"Fuller",
"George M.",
"",
"UCSD"
],
[
"Carlson",
"J.",
"",
"LANL"
],
[
"Qian",
"Yong-Zhong",
"",
"UMN"
]
] |
0707.0291 | Manfred Hartl | Manfred Hartl and S\'ebastien Leroy | On the second cohomology of semidirect products | 15 pages | null | null | LAMAV Preprint 07/10 | math.GR | null | Let $G$ be a group which is the semidirect product of a normal subgroup $N$
and a subgroup $T$, and let $M$ be a $G$-module with not necessarily trivial
$G$-action. Then we embed the simultaneous restriction map
$res=(res^G_N,res^G_T)^t : H^2(G,M) \to H^2(N,M)^T \times H^2(T,M)$ into a
natural five term exact sequence consisting of one and two-dimensional
cohomology groups of the factors $N$ and $T$. The elements of $H^2(G,M)$ are
represented in terms of group extensions of $G$ by $M$ constructed from
extensions of $N$ and $T$.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:14:31 GMT"
}
] | 2007-07-03T00:00:00 | [
[
"Hartl",
"Manfred",
""
],
[
"Leroy",
"Sébastien",
""
]
] |
0707.0292 | Orest Hrycyna | Aleksandra Kurek, Orest Hrycyna, Marek Szydlowski | Constraints on oscillating dark energy models | revtex4, 7 pages, 3 figures; (v2) 12 pages, 11 figures; Phys. Lett. B
(in press) | Phys.Lett.B659:14-25,2008 | 10.1016/j.physletb.2007.10.074 | null | astro-ph | null | The oscillating scenario of route to Lambda was recently proposed by us
arXiv:0704.1651 as an alternative to a cosmological constant in a explanation
of the current accelerating universe. In this scenario phantom scalar field
conformally coupled to gravity drives the accelerating phase of the universe.
In our model $\Lambda$CDM appears as a global attractor in the phase space. In
this paper we investigate observational constraints on this scenario from
recent measurements of distant supernovae type Ia, CMB R shift, BAO and $H(z)$
observational data. The Bayesian methods of model selection are used in
comparison the model with concordance $\Lambda$CDM one as well as with model
with dynamical dark energy parametrised by linear form. We conclude that
$\Lambda$CDM is favoured over FRW model with dynamical oscillating dark energy.
Our analysis also demonstrate that FRW model with oscillating dark energy is
favoured over FRW model with decaying dark energy parametrised in linear way.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:33:21 GMT"
},
{
"version": "v2",
"created": "Fri, 23 Nov 2007 16:31:04 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kurek",
"Aleksandra",
""
],
[
"Hrycyna",
"Orest",
""
],
[
"Szydlowski",
"Marek",
""
]
] |
0707.0293 | Chang-Yu Hou | Claudio Chamon, Chang-Yu Hou, Roman Jackiw, Christopher Mudry,
So-Young Pi, and Andreas P. Schnyder | Irrational vs. rational charge and statistics in two-dimensional quantum
systems | 4 pages, 2 figures | Phys.Rev.Lett.100:110405,2008 | 10.1103/PhysRevLett.100.110405 | null | cond-mat.str-el cond-mat.mes-hall hep-th math-ph math.MP | null | We show that quasiparticle excitations with irrational charge and irrational
exchange statistics exist in tight-biding systems described, in the continuum
approximation, by the Dirac equation in (2+1)-dimensional space and time. These
excitations can be deconfined at zero temperature, but when they are, the
charge re-rationalizes to the value 1/2 and the exchange statistics to that of
"quartons" (half-semions).
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:37:05 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Jul 2007 21:41:21 GMT"
},
{
"version": "v3",
"created": "Tue, 25 Mar 2008 20:19:54 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chamon",
"Claudio",
""
],
[
"Hou",
"Chang-Yu",
""
],
[
"Jackiw",
"Roman",
""
],
[
"Mudry",
"Christopher",
""
],
[
"Pi",
"So-Young",
""
],
[
"Schnyder",
"Andreas P.",
""
]
] |
0707.0294 | Alexey A. Petrov | Andriy Badin, Fabrizio Gabbiani and Alexey A. Petrov | Lifetime Difference in B_s mixing: Standard Model and beyond | 21 pages, 6 figures | Phys.Lett.B653:230-240,2007 | 10.1016/j.physletb.2007.07.049 | WSU-HEP-0702 | hep-ph | null | We present a calculation of 1/m^2_b corrections to the lifetime differences
of B_s mesons \Delta \Gamma_s in the heavy-quark expansion. We find that they
are small to significantly affect \Delta \Gamma_s and present the result for
lifetime difference including non-perturbative 1/m_b and 1/m_b^2 corrections.
We also analyze the generic \Delta B = 1 New Physics contributions to \Delta
\Gamma_s and provide several examples.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:53:39 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Badin",
"Andriy",
""
],
[
"Gabbiani",
"Fabrizio",
""
],
[
"Petrov",
"Alexey A.",
""
]
] |
0707.0295 | Savdeep Sethi | Savdeep Sethi | A Note on Heterotic Dualities via M-theory | 10 pages; references added; minor wording change | Phys.Lett.B659:385-387,2008 | 10.1016/j.physletb.2007.10.043 | null | hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that a class of torsional compactifications of the heterotic string
are dual to conventional Kahler heterotic string compactifications. This
observation follows from the recently proposed analogue of the c-map for the
heterotic string.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 19:52:52 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Aug 2007 07:04:33 GMT"
},
{
"version": "v3",
"created": "Wed, 29 Jun 2011 22:07:59 GMT"
}
] | 2011-07-01T00:00:00 | [
[
"Sethi",
"Savdeep",
""
]
] |
0707.0296 | Romualdo Tresguerres | Romualdo Tresguerres | Translations and dynamics | 22 Revtex pages, no figures. Published version with minor corrections | Int.J.Geom.Meth.Mod.Phys.5:905-945,2008 | 10.1142/S0219887808003120 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the role played by local translational symmetry in the context of
gauge theories of fundamental interactions. Translational connections and
fields are introduced, with special attention being paid to their universal
coupling to other variables, as well as to their contributions to field
equations and to conserved quantities.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:55:33 GMT"
},
{
"version": "v2",
"created": "Sun, 5 Oct 2008 16:55:01 GMT"
}
] | 2008-11-07T00:00:00 | [
[
"Tresguerres",
"Romualdo",
""
]
] |
0707.0297 | Kevin Beach | K. S. D. Beach | Fractal valence bond loops in a long-range Heisenberg model at
criticality | 4 + epsilon pages, 3 figures | null | null | null | cond-mat.str-el | null | We present a valence bond theory of the spin-S quantum Heisenberg model. For
nonfrustracting, local exchange and dimension d > 1, it predicts a resonating
ground state with bond amplitudes h(r) ~ (a^2+r^2)^(-p/2) and decay exponent
p=d+1. Different values of p can be achieved by introducing frustrating (p >
d+1) or nonfrustrating (p < d+1) long-range interactions. For d=2, but not d=3,
there is a critical value of the decay exponent p_c above which the ground
state is a spin liquid. The phase transition is analogous to quantum
percolation, with fractal valence bond loops playing the role of percolating
clusters. The critical exponents are continuously tunable along the phase
boundary p=p_c(a,S).
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:00:19 GMT"
}
] | 2007-07-04T00:00:00 | [
[
"Beach",
"K. S. D.",
""
]
] |
0707.0298 | Daniel Krefl | Sebastian Franco, Amihay Hanany, Daniel Krefl, Jaemo Park, Angel M.
Uranga and David Vegh | Dimers and Orientifolds | 72 pages, 42 figures; typos corrected and reference added | JHEP 0709:075,2007 | 10.1088/1126-6708/2007/09/075 | CERN-PH-TH/2007-099, IFT-UAM/CSIC-07-34, LMU-ASC 41/07, MIT-CTP
3846, MPP-2007-76, PUPT-2238 | hep-th | null | We introduce new techniques based on brane tilings to investigate D3-branes
probing orientifolds of toric Calabi-Yau singularities. With these new tools,
one can write down many orientifold models and derive the resulting low-energy
gauge theories living on the D-branes. Using the set of ideas in this paper one
recovers essentially all orientifolded theories known so far. Furthermore, new
orientifolds of non-orbifold toric singularities are obtained. The possible
applications of the tools presented in this paper are diverse. One particular
application is the construction of models which feature dynamical supersymmetry
breaking as well as the computation of D-instanton induced superpotential
terms.
| [
{
"version": "v1",
"created": "Tue, 3 Jul 2007 12:41:52 GMT"
},
{
"version": "v2",
"created": "Tue, 30 Oct 2007 09:57:29 GMT"
}
] | 2009-02-05T00:00:00 | [
[
"Franco",
"Sebastian",
""
],
[
"Hanany",
"Amihay",
""
],
[
"Krefl",
"Daniel",
""
],
[
"Park",
"Jaemo",
""
],
[
"Uranga",
"Angel M.",
""
],
[
"Vegh",
"David",
""
]
] |
0707.0299 | Kannan Soundararajan | K. Soundararajan | The distribution of smooth numbers in arithmetic progressions | 15 pages | null | null | null | math.NT | null | For a wide range of $x$ and $y$ we show that ${\Cal S}(x,y)$, the set of
integers below $x$ composed only of prime factors below $y$, is equidistributed
in the reduced residue classes $\pmod q$ for all $q<y^{4\sqrt{e}-\epsilon}$.
This improves earlier work of Granville; any improvement of this range of $q$
would have interesting consequences for Vinogradov's conjecture on the least
quadratic non-residue. For larger ranges of $q$ we prove the existence of a
large subgroup of the group of reduced residues such that ${\Cal S}(x,y)$ is
equidistributed within cosets of that subgroup.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:08:26 GMT"
}
] | 2007-07-04T00:00:00 | [
[
"Soundararajan",
"K.",
""
]
] |
0707.0300 | Taras Panov | Taras Panov and Nigel Ray | Categorical aspects of toric topology | 30 pages, LaTeX2e; minor changes in v2 | Contemp. Math., 460, Amer. Math. Soc., Providence, RI, 2008, pp.
293-322. | null | null | math.AT math.CT | null | We argue for the addition of category theory to the toolkit of toric
topology, by surveying recent examples and applications. Our case is made in
terms of toric spaces X_K, such as moment-angle complexes Z_K, quasitoric
manifolds M, and Davis-Januszkiewicz spaces DJ(K). We first exhibit X_K as the
homotopy colimit of a diagram of spaces over the small category cat(K), whose
objects are the faces of a finite simplicial complex K and morphisms their
inclusions. Then we study the corresponding cat(K)-diagrams in various
algebraic Quillen model categories, and interpret their homotopy colimits as
algebraic models for X_K. Such models encode many standard algebraic
invariants, and their existence is assured by the Quillen structure. We provide
several illustrative calculations, often over the rationals, including proofs
that quasitoric manifolds (and various generalisations) are rationally formal;
that the rational Pontrjagin ring of the loop space \Omega DJ(K) is isomorphic
to the quadratic dual of the Stanley-Reisner algebra Q[K] for flag complexes K;
and that DJ(K) is coformal precisely when K is flag. We conclude by describing
algebraic models for the loop space \Omega DJ(K) for any complex K, which mimic
our previous description as a homotopy colimit of topological monoids.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:08:28 GMT"
},
{
"version": "v2",
"created": "Sat, 16 Feb 2008 12:12:22 GMT"
}
] | 2008-11-09T00:00:00 | [
[
"Panov",
"Taras",
""
],
[
"Ray",
"Nigel",
""
]
] |
0707.0301 | Jeremy D. Schnittman | Jeremy D. Schnittman, Alessandra Buonanno (U Maryland), James R. van
Meter, John G. Baker (NASA Goddard), William D. Boggs (U Maryland), Joan
Centrella, Bernard J. Kelly (NASA Goddard), and Sean T. McWilliams (U
Maryland) | Anatomy of the binary black hole recoil: A multipolar analysis | 28 pages, 20 figures, submitted to PRD; v2: minor revisions from
referee report | Phys.Rev.D77:044031,2008 | 10.1103/PhysRevD.77.044031 | null | gr-qc astro-ph | null | We present a multipolar analysis of the gravitational recoil computed in
recent numerical simulations of binary black hole (BH) coalescence, for both
unequal masses and non-zero, non-precessing spins. We show that multipole
moments up to and including l=4 are sufficient to accurately reproduce the
final recoil velocity (within ~2%) and that only a few dominant modes
contribute significantly to it (within ~5%). We describe how the relative
amplitudes, and more importantly, the relative phases, of these few modes
control the way in which the recoil builds up throughout the inspiral, merger,
and ringdown phases. We also find that the numerical results can be reproduced
by an ``effective Newtonian'' formula for the multipole moments obtained by
replacing the radial separation in the Newtonian formulae with an effective
radius computed from the numerical data. Beyond the merger, the numerical
results are reproduced by a superposition of three Kerr quasi-normal modes
(QNMs). Analytic formulae, obtained by expressing the multipole moments in
terms of the fundamental QNMs of a Kerr BH, are able to explain the onset and
amount of ``anti-kick'' for each of the simulations. Lastly, we apply this
multipolar analysis to help explain the remarkable difference between the
amplitudes of planar and non-planar kicks for equal-mass spinning black holes.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:09:42 GMT"
},
{
"version": "v2",
"created": "Thu, 20 Dec 2007 15:58:48 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Schnittman",
"Jeremy D.",
"",
"U Maryland"
],
[
"Buonanno",
"Alessandra",
"",
"U Maryland"
],
[
"van Meter",
"James R.",
"",
"NASA Goddard"
],
[
"Baker",
"John G.",
"",
"NASA Goddard"
],
[
"Boggs",
"William D.",
"",
"U Maryland"
],
[
"Centrella",
"Joan",
"",
"NASA Goddard"
],
[
"Kelly",
"Bernard J.",
"",
"NASA Goddard"
],
[
"McWilliams",
"Sean T.",
"",
"U\n Maryland"
]
] |
0707.0302 | Don Summers | D. J. Summers (1), L. M. Cremaldi (1), R. Godang (1 and 2), B. R.
Kipapa (1), H. E. Rice (1), R. B. Palmer (3) ((1) University of Mississippi,
(2) University of South Alabama, (3) Brookhaven National Laboratory) | Muon Acceleration to 750 GeV in the Tevatron Tunnel for a 1.5 TeV mu+
mu- Collider | 3 pages, 2 figures, Particle Accelerator Conference (PAC 07),
Albuquerque, NM, 25-29 June 2007 | Conf.Proc.C070625:3178,2007 | null | PAC07-THPMS082, NFMCC-doc-515 | physics.acc-ph | null | Muon acceleration from 30 to 750 GeV in 72 orbits using two rings in the
1000m radius Tevatron tunnel is explored. The first ring ramps at 400 Hz and
accelerates muons from 30 to 400 GeV in 28 orbits using 14 GV of 1.3 GHz
superconducting RF. The ring duplicates the Fermilab 400 GeV main ring FODO
lattice, which had a 61m cell length. Muon survival is 80%. The second ring
accelerates muons from 400 to 750 GeV in 44 orbits using 8 GV of 1.3 GHz
superconducting RF. The 30 T/m main ring quadrupoles are lengthened 87% to
3.3m. The four main ring dipoles in each half cell are replaced by three
dipoles which ramp at 550 Hz from -1.8T to +1.8T interleaved with two 8T fixed
superconducting dipoles. The ramping and superconducting dipoles oppose each
other at 400 GeV and act in unison at 750 GeV. Muon survival is 92%. Two mm
copper wire, 0.28mm grain oriented silicon steel laminations, and a low duty
cycle mitigate eddy current losses. Low emittance muon bunches allow small
aperatures and permit magnets to ramp with a few thousand volts. Little civil
construction is required. The tunnel exists.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:10:50 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Summers",
"D. J.",
"",
"1 and 2"
],
[
"Cremaldi",
"L. M.",
"",
"1 and 2"
],
[
"Godang",
"R.",
"",
"1 and 2"
],
[
"Kipapa",
"B. R.",
""
],
[
"Rice",
"H. E.",
""
],
[
"Palmer",
"R. B.",
""
]
] |
0707.0303 | Ingo Steinwart | Ingo Steinwart, Don Hush, Clint Scovel | Learning from dependent observations | submitted to Journal of Multivariate Analysis | null | null | Los Alamos National Laboratory Technical Report LA-UR-06-3507 | stat.ML stat.ME | null | In most papers establishing consistency for learning algorithms it is assumed
that the observations used for training are realizations of an i.i.d. process.
In this paper we go far beyond this classical framework by showing that support
vector machines (SVMs) essentially only require that the data-generating
process satisfies a certain law of large numbers. We then consider the
learnability of SVMs for $\a$-mixing (not necessarily stationary) processes for
both classification and regression, where for the latter we explicitly allow
unbounded noise.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:16:49 GMT"
}
] | 2007-07-04T00:00:00 | [
[
"Steinwart",
"Ingo",
""
],
[
"Hush",
"Don",
""
],
[
"Scovel",
"Clint",
""
]
] |
0707.0304 | Joanna Brown | J.M. Brown, G.A. Blake, C.P. Dullemond, B. Merin, J.C. Augereau,
A.C.A. Boogert, N.J. Evans, II, V.C. Geers, F. Lahuis, J.E. Kessler-Silacci,
K.M. Pontoppidan, E.F. van Dishoeck | Cold Disks: Spitzer Spectroscopy of Disks around Young Stars with Large
Gaps | 13 pages, 3 figures, accepted to ApJL | null | 10.1086/520808 | null | astro-ph | null | We have identified four circumstellar disks with a deficit of dust emission
from their inner 15-50 AU. All four stars have F-G spectral type, and were
uncovered as part of the Spitzer Space Telescope ``Cores to Disks'' Legacy
Program Infrared Spectrograph (IRS) first look survey of ~100 pre-main sequence
stars. Modeling of the spectral energy distributions indicates a reduction in
dust density by factors of 100-1000 from disk radii between ~0.4 and 15-50 AU,
but with massive gas-rich disks at larger radii. This large contrast between
the inner and outer disk has led us to use the term `cold disks' to distinguish
these unusual systems. However, hot dust [0.02-0.2 Mmoon] is still present
close to the central star (R ~0.8 AU). We introduce the 30/13 micron, flux
density ratio as a new diagnostic for identifying cold disks. The mechanisms
for dust clearing over such large gaps are discussed. Though rare, cold disks
are likely in transition from an optically thick to an optically thin state,
and so offer excellent laboratories for the study of planet formation.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:17:29 GMT"
}
] | 2012-08-27T00:00:00 | [
[
"Brown",
"J. M.",
""
],
[
"Blake",
"G. A.",
""
],
[
"Dullemond",
"C. P.",
""
],
[
"Merin",
"B.",
""
],
[
"Augereau",
"J. C.",
""
],
[
"Boogert",
"A. C. A.",
""
],
[
"Evans",
"N. J.",
""
],
[
"II",
"",
""
],
[
"Geers",
"V. C.",
""
],
[
"Lahuis",
"F.",
""
],
[
"Kessler-Silacci",
"J. E.",
""
],
[
"Pontoppidan",
"K. M.",
""
],
[
"van Dishoeck",
"E. F.",
""
]
] |
0707.0305 | Christopher Morgan | Christopher W. Morgan (1 and 2), C.S. Kochanek (2), Nicholas D. Morgan
(2) and Emilio E. Falco (3) ((1) Department of Physics, U.S. Naval Academy
(2) Department of Astronomy, The Ohio State University (3)
Harvard-Smithsonian Center for Astrophysics) | The Quasar Accretion Disk Size - Black Hole Mass Relation | 5 pages, 3 figures, submitted to ApJL | null | 10.1088/0004-637X/712/2/1129 | null | astro-ph | null | We use the microlensing variability observed for nine gravitationally lensed
quasars to show that the accretion disk size at 2500 Angstroms is related to
the black hole mass by log(R_2500/cm) = (15.6+-0.2) +
(0.54+-0.28)log(M_BH/10^9M_sun). This scaling is consistent with the
expectation from thin disk theory (R ~ M_BH^(2/3)), but it implies that black
holes radiate with relatively low efficiency, log(eta) = -1.29+-0.44 +
log(L/L_E) where eta=L/(Mdot c^2). These sizes are also larger, by a factor of
~3, than the size needed to produce the observed 0.8 micron quasar flux by
thermal radiation from a thin disk with the same T ~ R^(-3/4) temperature
profile. More sophisticated disk models are clearly required, particularly as
our continuing observations improve the precision of the measurements and yield
estimates of the scaling with wavelength and accretion rate.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:21:22 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Morgan",
"Christopher W.",
"",
"1 and 2"
],
[
"Kochanek",
"C. S.",
""
],
[
"Morgan",
"Nicholas D.",
""
],
[
"Falco",
"Emilio E.",
""
]
] |
0707.0306 | Sean Matt | Sean Matt and Ralph E. Pudritz | The Nature of Stellar Winds in the Star-Disk Interaction | 7 pages, including 2 figures. To appear in proceedings of IAU
Symposium No. 243: Star-Disk Interaction in Young Stars | null | 10.1017/S1743921307009659 | null | astro-ph | null | Stellar winds may be important for angular momentum transport from accreting
T Tauri stars, but the nature of these winds is still not well-constrained. We
present some simulation results for hypothetical, hot (~1e6 K) coronal winds
from T Tauri stars, and we calculate the expected emission properties. For the
high mass loss rates required to solve the angular momentum problem, we find
that the radiative losses will be much greater than can be powered by the
accretion process. We place an upper limit to the mass loss rate from
accretion-powered coronal winds of ~1e-11 solar masses per year. We conclude
that accretion powered stellar winds are still a promising scenario for solving
the stellar angular momentum problem, but the winds must be cool (~1e4 K) and
thus are not driven by thermal pressure.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:25:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Matt",
"Sean",
""
],
[
"Pudritz",
"Ralph E.",
""
]
] |
0707.0307 | Brandon Peden | Brandon M. Peden, Rajiv Bhat, Meret Kr\"amer and Murray J. Holland | Quasi-angular momentum of Bose and Fermi gases in rotating optical
lattices | Added references, fixed typos, expanded introduction. 22 pages, 12
figures, accepted for publication in J. Phys. B (publication date: Sep 7,
2007) | J. Phys. B: At. Mol. Opt. Phys. 40 (2007) 3725-3744 | 10.1088/0953-4075/40/18/012 | null | cond-mat.other | null | The notion of quasi-angular momentum is introduced to label the eigenstates
of a Hamiltonian with a discrete rotational symmetry. This concept is recast in
an operatorial form where the creation and annihilation operators of a Hubbard
Hamiltonian carry units of quasi-angular momentum. Using this formalism, the
ground states of ultracold gases of non-interacting fermions in rotating
optical lattices are studied as a function of rotation, and transitions between
states of different quasi-angular momentum are identified. In addition,
previous results for strongly-interacting bosons are re-examined and compared
to the results for non-interacting fermions. Quasi-angular momentum can be used
to distinguish between these two cases. Finally, an experimentally accessible
signature of quasi-angular momentum is identified in the momentum distributions
of single-particle eigenstates.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:26:53 GMT"
},
{
"version": "v2",
"created": "Thu, 18 Oct 2007 22:13:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Peden",
"Brandon M.",
""
],
[
"Bhat",
"Rajiv",
""
],
[
"Krämer",
"Meret",
""
],
[
"Holland",
"Murray J.",
""
]
] |
0707.0308 | Dragomir Saric | Vladimir Markovic, Dragomir Saric | The Teichm\"uller distance between finite index subgroups of
$PSL_2(\mathbb{Z})$ | 23 pages, 5 Figures | null | null | null | math.CV math.GT | null | For a given $\epsilon >0$, we show that there exist two finite index
subgroups of $PSL_2(\mathbb{Z})$ which are $(1+\epsilon)$-quasisymmetrically
conjugated and the conjugation homeomorphism is not conformal. This implies
that for any $\epsilon>0$ there are two finite regular covers of the Modular
once punctured torus $T_0$ (or just the Modular torus) and a
$(1+\epsilon)$-quasiconformal between them that is not homotopic to a conformal
map. As an application of the above results, we show that the orbit of the
basepoint in the Teichm\"uller space $T(\S)$ of the punctured solenoid $\S$
under the action of the corresponding Modular group (which is the mapping class
group of $\S$ \cite{NS}, \cite{Odd}) has the closure in $T(\S)$ strictly larger
than the orbit and that the closure is necessarily uncountable.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:40:47 GMT"
}
] | 2007-07-04T00:00:00 | [
[
"Markovic",
"Vladimir",
""
],
[
"Saric",
"Dragomir",
""
]
] |
0707.0309 | Vladimir R. V. de Assis | Vladimir R. V. Assis and Mauro Copelli | Dynamic range of hypercubic stochastic excitable media | 7 pages, 4 figures | Phys. Rev. E 77, 011923 (2008) | 10.1103/PhysRevE.77.011923 | null | q-bio.NC cond-mat.dis-nn cond-mat.stat-mech nlin.CG physics.bio-ph | null | We study the response properties of d-dimensional hypercubic excitable
networks to a stochastic stimulus. Each site, modelled either by a three-state
stochastic susceptible-infected-recovered-susceptible system or by the
probabilistic Greenberg-Hastings cellular automaton, is continuously and
independently stimulated by an external Poisson rate h. The response function
(mean density of active sites rho versus h) is obtained via simulations (for
d=1, 2, 3, 4) and mean field approximations at the single-site and pair levels
(for all d). In any dimension, the dynamic range of the response function is
maximized precisely at the nonequilibrium phase transition to self-sustained
activity, in agreement with a reasoning recently proposed. Moreover, the
maximum dynamic range attained at a given dimension d is a decreasing function
of d.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:28:44 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Feb 2008 18:11:18 GMT"
}
] | 2008-02-13T00:00:00 | [
[
"Assis",
"Vladimir R. V.",
""
],
[
"Copelli",
"Mauro",
""
]
] |
0707.0310 | Vladislav Kupriyanov | D.M. Gitman and V.G. Kupriyanov | Path integral representations in noncommutative quantum mechanics and
noncommutative version of Berezin-Marinov action | null | Eur.Phys.J.C54:325-332,2008 | 10.1140/epjc/s10052-007-0518-x | null | hep-th | null | It is known that actions of field theories on a noncommutative space-time can
be written as some modified (we call them $\theta$-modified) classical actions
already on the commutative space-time (introducing a star product). Then the
quantization of such modified actions reproduces both space-time
noncommutativity and usual quantum mechanical features of the corresponding
field theory. The $\theta$-modification for arbitrary finite-dimensional
nonrelativistic system was proposed by Deriglazov (2003). In the present
article, we discuss the problem of constructing $\theta$-modified actions for
relativistic QM. We construct such actions for relativistic spinless and
spinning particles. The key idea is to extract $\theta$-modified actions of the
relativistic particles from path integral representations of the corresponding
noncommtative field theory propagators. We consider Klein-Gordon and Dirac
equations for the causal propagators in such theories. Then we construct for
the propagators path-integral representations. Effective actions in such
representations we treat as $\theta$-modified actions of the relativistic
particles. To confirm the interpretation, we quantize canonically these
actions. Thus, we obtain the Klein-Gordon and Dirac equations in the
noncommutative field theories. The $\theta$-modified action of the relativistic
spinning particle is just a generalization of the Berezin-Marinov
pseudoclassical action for the noncommutative case.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:29:38 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Jul 2007 21:27:55 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Gitman",
"D. M.",
""
],
[
"Kupriyanov",
"V. G.",
""
]
] |
0707.0311 | G\"unter Rote | Rom Pinchasi and G\"unter Rote | On the maximum size of an anti-chain of linearly separable sets and
convex pseudo-discs | 10 pages, 3 figures. revised version correctly attributes the idea of
Section 3 to Tverberg; and replaced k-sets by "linearly separable sets" in
the paper and the title. Accepted for publication in Israel Journal of
Mathematics | Israel Journal of Mathematics 172 (2009), 337-348 | 10.1007/s11856-009-0076-z | null | math.MG | null | We show that the maximum cardinality of an anti-chain composed of
intersections of a given set of n points in the plane with half-planes is close
to quadratic in n. We approach this problem by establishing the equivalence
with the problem of the maximum monotone path in an arrangement of n lines. For
a related problem on antichains in families of convex pseudo-discs we can
establish the precise asymptotic bound: it is quadratic in n. The sets in such
a family are characterized as intersections of a given set of n points with
convex sets, such that the difference between the convex hulls of any two sets
is nonempty and connected.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:45:52 GMT"
},
{
"version": "v2",
"created": "Tue, 8 Jan 2008 16:08:06 GMT"
}
] | 2015-02-18T00:00:00 | [
[
"Pinchasi",
"Rom",
""
],
[
"Rote",
"Günter",
""
]
] |
0707.0312 | Noelia Estella Donata No\"el | Noelia Noel and Carme Gallart (1) ((1) Instituto de Astrofisica de
Canarias) | Stellar Populations in the Outskirts of the Small Magellanic Cloud: No
Outer Edge Yet | Accepted for publication in ApJ Letters. High resolution figures are
available at ftp://ftp.iac.es/out/noe/ | Astrophys.J.665:L23-L26,2007 | 10.1086/521223 | null | astro-ph | null | We report the detection of intermediate-age and old stars belonging to the
SMC at 6.5 kpc from the SMC center in the southern direction. We show, from the
analysis of three high quality 34\arcmin $\times$ 33\arcmin CMDs, that the age
composition of the stellar population is similar at galactocentric distances of
$\thicksim$4.7 kpc, $\thicksim$5.6 kpc, and $\thicksim$6.5 kpc. The surface
brightness profile of the SMC follows an exponential law, with no evidence of
truncation, all the way out to 6.5 kpc. These results, taken together, suggest
that the SMC `disk' population is dominating over a possible old Milky Way-like
stellar halo, and that the SMC may be significantly larger than previously
thought.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:37:27 GMT"
}
] | 2010-03-01T00:00:00 | [
[
"Noel",
"Noelia",
""
],
[
"Gallart",
"Carme",
""
]
] |
0707.0313 | Peter K. Friz | Peter Friz and Nicolas Victoir | Differential Equations Driven by Gaussian Signals I | null | null | null | null | math.PR | null | We consider multi-dimensional Gaussian processes and give a new condition on
the covariance, simple and sharp, for the existence of stochastic area(s).
Gaussian rough paths are constructed with a variety of weak and strong
approximation results. Together with a new RKHS embedding, we obtain a powerful
- yet conceptually simple - framework in which to analysize differential
equations driven by Gaussian signals in the rough paths sense.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:39:04 GMT"
}
] | 2007-07-04T00:00:00 | [
[
"Friz",
"Peter",
""
],
[
"Victoir",
"Nicolas",
""
]
] |
0707.0314 | Yamac Pehlivan | Satoru Odake, Yamac Pehlivan, Ryu Sasaki | Interpolation of SUSY quantum mechanics | 18 pages | J.Phys.A40:11973-11986,2007 | 10.1088/1751-8113/40/39/017 | null | math-ph hep-th math.MP nucl-th | null | Interpolation of two adjacent Hamiltonians in SUSY quantum mechanics
$H_s=(1-s)A^{\dagger}A + sAA^{\dagger}$, $0\le s\le 1$ is discussed together
with related operators. For a wide variety of shape-invariant degree one
quantum mechanics and their `discrete' counterparts, the interpolation
Hamiltonian is also shape-invariant, that is it takes the same form as the
original Hamiltonian with shifted coupling constant(s).
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:39:48 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Odake",
"Satoru",
""
],
[
"Pehlivan",
"Yamac",
""
],
[
"Sasaki",
"Ryu",
""
]
] |
0707.0315 | Jan Vondrak | Benny Sudakov, Jan Vondrak | How many random edges make a dense hypergraph non-2-colorable? | null | null | null | null | math.CO | null | We study a model of random uniform hypergraphs, where a random instance is
obtained by adding random edges to a large hypergraph of a given density. We
obtain a tight bound on the number of random edges required to ensure
non-2-colorability. We prove that for any k-uniform hypergraph with
Omega(n^{k-epsilon}) edges, adding omega(n^{k epsilon/2}) random edges makes
the hypergraph almost surely non-2-colorable. This is essentially tight, since
there is a 2-colorable hypergraph with Omega(n^{k-\epsilon}) edges which almost
surely remains 2-colorable even after adding o(n^{k \epsilon / 2}) random
edges.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:48:56 GMT"
}
] | 2007-07-04T00:00:00 | [
[
"Sudakov",
"Benny",
""
],
[
"Vondrak",
"Jan",
""
]
] |
0707.0316 | Piotr Mi{\l}o\'s | Piotr Milos | Occupation time fluctuations of Poisson and equilibrium branching
systems in critical and large dimensions | null | Prob. and Math. Stat. Vol. 278, Fasc. 2 (2008) pp. 235-256 | null | null | math.PR | null | Limit theorems are presented for the rescaled occupation time fluctuation
process of a critical finite variance branching particle system in
$\mathbb{R}^{d}$ with symmetric $\alpha$-stable motion starting off from either
a standard Poisson random field or the equilibrium distribution for critical
$d=2\alpha$ and large $d>2\alpha$ dimensions. The limit processes are
generalised Wiener processes. The obtained convergence is in space-time,
finite-dimensional distributions sense. With the addtional assumption on the
branching law we obtain functional convergence.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 20:50:04 GMT"
}
] | 2009-11-04T00:00:00 | [
[
"Milos",
"Piotr",
""
]
] |
0707.0317 | Marco Cavagli\`a | Marco Cavaglia, Romulus Godang, Lucien M. Cremaldi and Donald J.
Summers | Signatures of black holes at the LHC | 13 pages, 7 figures | JHEP 0706:055,2007 | 10.1088/1126-6708/2007/06/055 | null | hep-ph gr-qc hep-th | null | Signatures of black hole events at CERN's Large Hadron Collider are
discussed. Event simulations are carried out with the Fortran Monte Carlo
generator CATFISH. Inelasticity effects, exact field emissivities, color and
charge conservation, corrections to semiclassical black hole evaporation,
gravitational energy loss at formation and possibility of a black hole remnant
are included in the analysis.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 21:23:59 GMT"
}
] | 2010-02-03T00:00:00 | [
[
"Cavaglia",
"Marco",
""
],
[
"Godang",
"Romulus",
""
],
[
"Cremaldi",
"Lucien M.",
""
],
[
"Summers",
"Donald J.",
""
]
] |
0707.0318 | Clarina dela Cruz | C. R. dela Cruz, B. Lorenz, Y.Y. Sun, Y. Wang, S.Park, S-W. Cheong, M.
M. Gospodinov, and C. W. Chu | Pressure induced enhancement of ferroelectricity in multiferroic
$R$Mn$_2$O$_5$($R$=Tb,Dy, and Ho) | 8 pages, 6 figures, submitted for review in Phys. Rev. B | null | 10.1103/PhysRevB.76.174106 | null | cond-mat.str-el | null | Measurements of ferroelectric polarization and dielectric constant were done
on $R$Mn$_2$O$_5$ ($R$=Tb, Dy, and Ho) with applied hydrostatic pressures of up
to 18 kbar. At ambient pressure, distinctive anomalies were observed in the
temperature profile of both physical properties at critical temperatures
marking the onset of long range AFM order (T$_{N1}$), ferroelectricity
(T$_{C1}$) as well as at temperatures when anomalous changes in the
polarization, dielectric constant and spin wave commensurability have been
previously reported. In particular, the step in the dielectric constant at low
temperatures (T$_{C2}$), associated with both a drop in the ferroelectric
polarization and an incommensurate magnetic structure, was shown to be suddenly
quenched upon passing an $R$-dependent critical pressure. This was shown to
correlate with the stabilization of the high ferroelectric polarization state
which is coincident with the commensurate magnetic structure. The observation
is suggested to be due to a pressure induced phase transition into a
commensurate magnetic structure as exemplified by the pressure-temperature
($p$-$T$) phase diagrams constructed in this work. The $p$-$T$ phase diagrams
are determined for all three compounds.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 21:39:24 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Cruz",
"C. R. dela",
""
],
[
"Lorenz",
"B.",
""
],
[
"Sun",
"Y. Y.",
""
],
[
"Wang",
"Y.",
""
],
[
"Park",
"S.",
""
],
[
"Cheong",
"S-W.",
""
],
[
"Gospodinov",
"M. M.",
""
],
[
"Chu",
"C. W.",
""
]
] |
0707.0319 | Ludovic Berthier | Antoine Carr\'e, Ludovic Berthier, Juergen Horbach, Simona Ispas,
Walter Kob | Amorphous silica modeled with truncated and screened Coulomb
interactions: A molecular dynamics simulation study | 10 pages; 11 figs | J. Chem. Phys. 127, 114512 (2007) | 10.1063/1.2777136 | null | cond-mat.stat-mech | null | We show that finite-range alternatives to the standard long-range BKS pair
potential for silica might be used in molecular dynamics simulations. We study
two such models that can be efficiently simulated since no Ewald summation is
required. We first consider the Wolf method, where the Coulomb interactions are
truncated at a cutoff distance r_c such that the requirement of charge
neutrality holds. Various static and dynamic quantities are computed and
compared to results from simulations using Ewald summations. We find very good
agreement for r_c ~ 10 Angstroms. For lower values of r_c, the long--range
structure is affected which is accompanied by a slight acceleration of dynamic
properties. In a second approach, the Coulomb interaction is replaced by an
effective Yukawa interaction with two new parameters determined by a force
fitting procedure. The same trend as for the Wolf method is seen. However,
slightly larger cutoffs have to be used in order to obtain the same accuracy
with respect to static and dynamic quantities as for the Wolf method.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 21:49:05 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Carré",
"Antoine",
""
],
[
"Berthier",
"Ludovic",
""
],
[
"Horbach",
"Juergen",
""
],
[
"Ispas",
"Simona",
""
],
[
"Kob",
"Walter",
""
]
] |
0707.0320 | Wu-Ki Tung | Wu-Ki Tung, H.L. Lai, J. Pumplin, P. Nadolsky, and C.-P. Yuan | Heavy Quark Mass Effects in PQCD and Heavy Flavor Parton Distributions | Contribution to the proceedings of the DIS2007 Workshop, Munich,
Germany, April, 2007 | null | 10.1142/9789812706706_0022 | null | hep-ph | null | The systematic treatment of heavy quark mass effects in DIS in current CTEQ
global analysis is summarized. Applications of this treatment to the comparison
between theory and experimental data on DIS charm production are described. The
possibility of intrinsic charm in the nucleon is studied. The issue of
determining the charm mass in global analysis is discussed.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 22:19:16 GMT"
}
] | 2017-08-23T00:00:00 | [
[
"Tung",
"Wu-Ki",
""
],
[
"Lai",
"H. L.",
""
],
[
"Pumplin",
"J.",
""
],
[
"Nadolsky",
"P.",
""
],
[
"Yuan",
"C. -P.",
""
]
] |
0707.0321 | Zbigniew Koza | Maciej Matyka and Zbigniew Koza | Spreading of a density front in the K\"untz-Lavall\'ee model of porous
media | null | J. Phys. D: Appl. Phys. 40, 4078-4083 (2007) | 10.1088/0022-3727/40/13/026 | null | physics.flu-dyn physics.class-ph | null | We analyze spreading of a density front in the K\"untz-Lavall\'ee model of
porous media. In contrast to previous studies, where unusual properties of the
front were attributed to anomalous diffusion, we find that the front evolution
is controlled by normal diffusion and hydrodynamic flow, the latter being
responsible for apparent enhancement of the front propagation speed. Our
finding suggests that results of several recent experiments on porous media,
where anomalous diffusion was reported based on the density front propagation
analysis, should be reconsidered to verify the role of a fluid flow.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 22:54:23 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Matyka",
"Maciej",
""
],
[
"Koza",
"Zbigniew",
""
]
] |
0707.0322 | Marian Anghel | Ingo Steinwart, Marian Anghel | Consistency of support vector machines for forecasting the evolution of
an unknown ergodic dynamical system from observations with unknown noise | Published in at http://dx.doi.org/10.1214/07-AOS562 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org) | Annals of Statistics 2009, Vol. 37, No. 2, 841-875 | 10.1214/07-AOS562 | IMS-AOS-AOS562 | stat.ME math.DS math.ST stat.TH | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the problem of forecasting the next (observable) state of an
unknown ergodic dynamical system from a noisy observation of the present state.
Our main result shows, for example, that support vector machines (SVMs) using
Gaussian RBF kernels can learn the best forecaster from a sequence of noisy
observations if (a) the unknown observational noise process is bounded and has
a summable $\alpha$-mixing rate and (b) the unknown ergodic dynamical system is
defined by a Lipschitz continuous function on some compact subset of
$\mathbb{R}^d$ and has a summable decay of correlations for Lipschitz
continuous functions. In order to prove this result we first establish a
general consistency result for SVMs and all stochastic processes that satisfy a
mixing notion that is substantially weaker than $\alpha$-mixing.
| [
{
"version": "v1",
"created": "Mon, 2 Jul 2007 23:56:10 GMT"
},
{
"version": "v2",
"created": "Tue, 7 Apr 2009 14:20:48 GMT"
}
] | 2009-04-07T00:00:00 | [
[
"Steinwart",
"Ingo",
""
],
[
"Anghel",
"Marian",
""
]
] |
0707.0323 | Syed Jafar | Viveck R. Cadambe, Syed A. Jafar | Interference Alignment and the Degrees of Freedom for the K User
Interference Channel | 30 pages. Revision extends the 3 user proof to K users | null | null | null | cs.IT math.IT | null | While the best known outerbound for the K user interference channel states
that there cannot be more than K/2 degrees of freedom, it has been conjectured
that in general the constant interference channel with any number of users has
only one degree of freedom. In this paper, we explore the spatial degrees of
freedom per orthogonal time and frequency dimension for the K user wireless
interference channel where the channel coefficients take distinct values across
frequency slots but are fixed in time. We answer five closely related
questions. First, we show that K/2 degrees of freedom can be achieved by
channel design, i.e. if the nodes are allowed to choose the best constant,
finite and nonzero channel coefficient values. Second, we show that if channel
coefficients can not be controlled by the nodes but are selected by nature,
i.e., randomly drawn from a continuous distribution, the total number of
spatial degrees of freedom for the K user interference channel is almost surely
K/2 per orthogonal time and frequency dimension. Thus, only half the spatial
degrees of freedom are lost due to distributed processing of transmitted and
received signals on the interference channel. Third, we show that interference
alignment and zero forcing suffice to achieve all the degrees of freedom in all
cases. Fourth, we show that the degrees of freedom $D$ directly lead to an
$\mathcal{O}(1)$ capacity characterization of the form
$C(SNR)=D\log(1+SNR)+\mathcal{O}(1)$ for the multiple access channel, the
broadcast channel, the 2 user interference channel, the 2 user MIMO X channel
and the 3 user interference channel with M>1 antennas at each node. Fifth, we
characterize the degree of freedom benefits from cognitive sharing of messages
on the 3 user interference channel.
| [
{
"version": "v1",
"created": "Tue, 3 Jul 2007 15:26:19 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jul 2007 01:28:41 GMT"
}
] | 2007-07-13T00:00:00 | [
[
"Cadambe",
"Viveck R.",
""
],
[
"Jafar",
"Syed A.",
""
]
] |
0707.0324 | Philip Fellman | Philip V. Fellman and Jonathan Vos Post | Quantum Nash Equilibria and Quantum Computing | 18 Pages, 6th International Conference on Complex Systems. Available
from http://necsi.org/events/iccs6/papers/12dc335ba096f7ee3cf094c55489.pdf | InterJournal Complex Systems, 1846, 2006 | 10.1007/978-3-540-85081-6_56 | null | q-fin.GN physics.comp-ph physics.soc-ph q-fin.CP | null | In this paper we review our earlier work on quantum computing and the Nash
Equilibrium, in particular, tracing the history of the discovery of new Nash
Equilibria and then reviewing the ways in which quantum computing may be
expected to generate new classes of Nash equilibria. We then extend this work
through a substantive analysis of examples provided by Meyer, Flitney, Iqbal
and Weigert and Cheon and Tsutsui with respect to quantized games, quantum game
strategies and the extension of Nash Equilibrium to solvable games in Hilbert
space. Finally, we review earlier work by Sato, Taiji and Ikegami on non-linear
computation and computational classes by way of reference to coherence,
decoherence and quantum computating systems.
| [
{
"version": "v1",
"created": "Tue, 3 Jul 2007 00:09:03 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Fellman",
"Philip V.",
""
],
[
"Post",
"Jonathan Vos",
""
]
] |
0707.0325 | Mark Caprio | M. A. Caprio, P. Cejnar, F. Iachello | Excited state quantum phase transitions in many-body systems | LaTeX (elsart), 37 pages; to be published in Ann. Phys. (N.Y.) | Ann. Phys. (N.Y.) 323, 1106 (2008) | 10.1016/j.aop.2007.06.011 | null | quant-ph nucl-th | null | Phenomena analogous to ground state quantum phase transitions have recently
been noted to occur among states throughout the excitation spectra of certain
many-body models. These excited state phase transitions are manifested as
simultaneous singularities in the eigenvalue spectrum (including the gap or
level density), order parameters, and wave function properties. In this
article, the characteristics of excited state quantum phase transitions are
investigated. The finite-size scaling behavior is determined at the mean field
level. It is found that excited state quantum phase transitions are universal
to two-level bosonic and fermionic models with pairing interactions.
| [
{
"version": "v1",
"created": "Tue, 3 Jul 2007 00:09:24 GMT"
}
] | 2008-05-06T00:00:00 | [
[
"Caprio",
"M. A.",
""
],
[
"Cejnar",
"P.",
""
],
[
"Iachello",
"F.",
""
]
] |
0707.0326 | Machiko Hatsuda | Machiko Hatsuda and Kiyoshi Kamimura | Projective Coordinates and Projective Space Limit | 16 pages, v2: modified the section 2.1 clarifying the difference from
IW contraction, added notes & references, version to appear in Nuclear
Physics B | Nucl.Phys.B798:310-322,2008 | 10.1016/j.nuclphysb.2008.02.004 | null | hep-th | null | The "projective lightcone limit" has been proposed as an alternative
holographic dual of an AdS space. It is a new type of group contraction for a
coset G/H preserving the isometry group G but changing H. In contrast to the
usual group contraction, which changes G preserving the spacetime dimension, it
reduces the dimensions of the spacetime on which G is realized. The obtained
space is a projective space on which the isometry is realized as a linear
fractional transformation. We generalize and apply this limiting procedure to
the "Hopf reduction" and obtain (n-1)-dimensional complex projective space from
(2n-1)-dimensional sphere preserving SU(n) symmetry.
| [
{
"version": "v1",
"created": "Tue, 3 Jul 2007 01:12:30 GMT"
},
{
"version": "v2",
"created": "Fri, 8 Feb 2008 07:34:34 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hatsuda",
"Machiko",
""
],
[
"Kamimura",
"Kiyoshi",
""
]
] |
0707.0327 | Austin Lund | A. P. Lund, T. C. Ralph and H. L. Haselgrove | Fault-tolerant linear optical quantum computing with small-amplitude
coherent states | null | null | 10.1103/PhysRevLett.100.030503 | null | quant-ph | null | Quantum computing using two optical coherent states as qubit basis states has
been suggested as an interesting alternative to single photon optical quantum
computing with lower physical resource overheads. These proposals have been
questioned as a practical way of performing quantum computing in the short term
due to the requirement of generating fragile diagonal states with large
coherent amplitudes. Here we show that by using a fault-tolerant error
correction scheme, one need only use relatively small coherent state amplitudes
($\alpha > 1.2$) to achieve universal quantum computing. We study the effects
of small coherent state amplitude and photon loss on fault tolerance within the
error correction scheme using a Monte Carlo simulation and show the quantity of
resources used for the first level of encoding is orders of magnitude lower
than the best known single photon scheme. %We study this reigem using a Monte
Carlo simulation and incorporate %the effects of photon loss in this
simulation.
| [
{
"version": "v1",
"created": "Tue, 3 Jul 2007 01:16:50 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lund",
"A. P.",
""
],
[
"Ralph",
"T. C.",
""
],
[
"Haselgrove",
"H. L.",
""
]
] |
0707.0328 | Raphael Granier de Cassagnac | Raphael Granier de Cassagnac | What's the matter at RHIC? | 14 pages, 8 figures, talk given at the CTP 2007 Symposiun on
Sypersymmetry at LHC, Cairo, March 2007. Proceedings to appear in the
International Journal of Modern Physics A. (Improve references and add minor
comments) | Int.J.Mod.Phys.A22:6043-6056,2007 | 10.1142/S0217751X07039225 | null | nucl-ex | null | I present here a concise review of the experimental results obtained at the
Relativistic Heavy Ion Collider (RHIC), which shed light on the hot and dense
quark gluon matter produced at these high temperature and density conditions.
| [
{
"version": "v1",
"created": "Tue, 3 Jul 2007 01:30:32 GMT"
},
{
"version": "v2",
"created": "Thu, 12 Jul 2007 18:41:17 GMT"
}
] | 2010-11-03T00:00:00 | [
[
"de Cassagnac",
"Raphael Granier",
""
]
] |
0707.0329 | Mareike Fischer | Mareike Fischer, Mike Steel | Expected Anomalies in the Fossil Record | null | Fischer, M. and Steel, M. (2008). Expected anomalies in the fossil
record. Evolutionary bioinformatics online 4: 61--67 | null | null | q-bio.PE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The problem of intermediates in the fossil record has been frequently
discussed ever since Darwin. The extent of `gaps' (missing transitional stages)
has been used to argue against gradual evolution from a common ancestor.
Traditionally, gaps have often been explained by the improbability of
fossilization and the discontinuous selection of found fossils. Here we take an
analytical approach and demonstrate why, under certain sampling conditions, we
may not expect intermediates to be found. Using a simple null model, we show
mathematically that the question of whether a taxon sampled from some time in
the past is likely to be morphologically intermediate to other samples (dated
earlier and later) depends on the shape and dimensions of the underlying
phylogenetic tree that connects the taxa, and the times from which the fossils
are sampled.
| [
{
"version": "v1",
"created": "Tue, 3 Jul 2007 01:24:43 GMT"
},
{
"version": "v2",
"created": "Tue, 26 Aug 2008 23:50:22 GMT"
}
] | 2008-08-27T00:00:00 | [
[
"Fischer",
"Mareike",
""
],
[
"Steel",
"Mike",
""
]
] |
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