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0706.0914
Chris J. Willott
Chris J. Willott, Philippe Delorme, Alain Omont, Jacqueline Bergeron, Xavier Delfosse, Thierry Forveille, Loic Albert, Celine Reyle, Gary J. Hill, Michael Gully-Santiago, Phillip Vinten, David Crampton, John B. Hutchings, David Schade, Luc Simard, Marcin Sawicki, Alexandre Beelen, Pierre Cox
Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey
15 pages, 9 figures, AJ, in press, minor changes to previous version
Astron.J.134:2435-2450,2007
10.1086/522962
null
astro-ph
null
The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars at redshift greater than 6, including the most distant known quasar, CFHQS J2329-0301 at z=6.43. We describe the observational method used to identify the quasars and present optical, infrared, and millimeter photometry and optical and near-infrared spectroscopy. We investigate the dust properties of these quasars finding an unusual dust extinction curve for one quasar and a high far-infrared luminosity due to dust emission for another. The mean millimeter continuum flux for CFHQS quasars is substantially lower than that for SDSS quasars at the same redshift, likely due to a correlation with quasar UV luminosity. For two quasars with sufficiently high signal-to-noise optical spectra, we use the spectra to investigate the ionization state of hydrogen at z>5. For CFHQS J1509-1749 at z=6.12, we find significant evolution (beyond a simple extrapolation of lower redshift data) in the Gunn-Peterson optical depth at z>5.4. The line-of-sight to this quasar has one of the highest known optical depths at z~5.8. An analysis of the sizes of the highly-ionized near-zones in the spectra of two quasars at z=6.12 and z=6.43 suggest the IGM surrounding these quasars was substantially ionized before these quasars turned on. Together, these observations point towards an extended reionization process, but we caution that cosmic variance is still a major limitation in z>6 quasar observations.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 21:02:56 GMT" }, { "version": "v2", "created": "Thu, 30 Aug 2007 15:41:28 GMT" } ]
2009-06-23T00:00:00
[ [ "Willott", "Chris J.", "" ], [ "Delorme", "Philippe", "" ], [ "Omont", "Alain", "" ], [ "Bergeron", "Jacqueline", "" ], [ "Delfosse", "Xavier", "" ], [ "Forveille", "Thierry", "" ], [ "Albert", "Loic", "" ], [ "Reyle", "Celine", "" ], [ "Hill", "Gary J.", "" ], [ "Gully-Santiago", "Michael", "" ], [ "Vinten", "Phillip", "" ], [ "Crampton", "David", "" ], [ "Hutchings", "John B.", "" ], [ "Schade", "David", "" ], [ "Simard", "Luc", "" ], [ "Sawicki", "Marcin", "" ], [ "Beelen", "Alexandre", "" ], [ "Cox", "Pierre", "" ] ]
0706.0915
Andrzej Wi\'snicki
Stanis{\l}aw Prus and Andrzej Wi\'snicki
On the fixed point property in direct sums of Banach spaces with strictly monotone norms
corrected and extended version, 13 pages
Studia Mathematica 186 (2008), 87--99
10.4064/sm186-1-8
null
math.FA
null
It is shown that if a Banach space X has the weak Banach-Saks property and the weak fixed point property for nonexpansive mappings and Y satisfies property asymptotic (P) (which is weaker than the condition WCS(Y)>1), then the direct sum of X and Y endowed with a strictly monotone norm enjoys the weak fixed point property. The same conclusion is valid if X admits a 1-unconditional basis.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 21:06:29 GMT" }, { "version": "v2", "created": "Wed, 14 Nov 2007 23:28:52 GMT" } ]
2015-11-24T00:00:00
[ [ "Prus", "Stanisław", "" ], [ "Wiśnicki", "Andrzej", "" ] ]
0706.0916
Deborah Prezzi
D. Prezzi, D. Varsano, A. Ruini, A. Marini, and E. Molinari
Optical properties of graphene nanoribbons: the role of many-body effects
5 pages, 3 figures
null
10.1103/PhysRevB.77.041404
null
cond-mat.mtrl-sci
null
We investigate from first principles the optoelectronic properties of nanometer-sized armchair graphene nanoribbons (GNRs). We show that many-body effects are essential to correctly describe both energy gaps and optical response. As a signature of the confined geometry, we observe strongly bound excitons dominating the optical spectra, with a clear family dependent binding energy. Our results demonstrate that GNRs constitute 1D nanostructures whose absorption and luminescence performance can be controlled by changing both family and edge termination.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 21:16:43 GMT" } ]
2009-11-13T00:00:00
[ [ "Prezzi", "D.", "" ], [ "Varsano", "D.", "" ], [ "Ruini", "A.", "" ], [ "Marini", "A.", "" ], [ "Molinari", "E.", "" ] ]
0706.0917
Stephen G. Naculich
Howard J. Schnitzer
Reggeization of N=8 Supergravity and N=4 Yang-Mills Theory II
13 pages, 1 figure; v2: minor changes, a correction, and added references
null
null
BRX-TH-588
hep-th
null
The loop expansion for the n-point functions of N=4 Yang-Mills theory and N=8 supergravity can be formulated as the loop expansion of scalar field theory with an infinite subclass being the ladder diagrams. We consider the sum of ladder diagrams for gluon-gluon and graviton-graviton scattering in the Regge limit. The reggeization of the gluon and the graviton is discussed in this context and that of hep-th/0701217. If the Bern, Dixon, Smirnov conjecture for planar gluon-gluon scattering is correct, then the ladder sum for SU(N) gauge theory at large N, correctly gives the Regge limit, with Regge trajectory function proportional to the cusp anomalous dimension. In graviton-graviton scattering it is argued that the graviton lies on a Regge trajectory. Regge cuts are also present due to infinite sums of non-planar graphs. The multiple exchange of Regge poles in non-planar graphs can give a countable infinite number of moving Regge cuts which accumulate near s=0. It is conjectured that this may be related to the infinite number of non-perturbative massless states which remain in the limit discussed by Green, Ooguri and Schwarz.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 19:34:31 GMT" }, { "version": "v2", "created": "Fri, 17 Aug 2007 18:16:34 GMT" } ]
2011-11-10T00:00:00
[ [ "Schnitzer", "Howard J.", "" ] ]
0706.0918
Rikard Enberg
R. Enberg, P. J. Fox, L. J. Hall, A. Y. Papaioannou, M. Papucci
LHC and Dark Matter Signals of Improved Naturalness
33 pages, 13 figures. Minor changes: version to appear in JHEP
JHEP 0711:014,2007
10.1088/1126-6708/2007/11/014
LBNL-62748, UCB-PTH-07/10
hep-ph
null
The Standard Model Higgs suffers from the hierarchy problem, typically implying new states within the reach of the LHC. If the Higgs is very heavy (~500 GeV) the states that cutoff the quadratic divergence may be beyond the reach of the LHC. However, in this case precision electroweak data require the Standard Model to be augmented with new states at the electroweak scale. We study a very simple model, with no new colored states, that allows a heavy Higgs whilst remaining consistent with experiments, and yielding the correct dark matter abundance. We investigate the possibilities for its discovery at the LHC and future dark matter detection experiments.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 22:15:58 GMT" }, { "version": "v2", "created": "Mon, 29 Oct 2007 23:02:01 GMT" } ]
2014-11-18T00:00:00
[ [ "Enberg", "R.", "" ], [ "Fox", "P. J.", "" ], [ "Hall", "L. J.", "" ], [ "Papaioannou", "A. Y.", "" ], [ "Papucci", "M.", "" ] ]
0706.0919
Zoltan Ligeti
Zoltan Ligeti
Mixing and CP violation in the D0 and Bs systems
Invited talk at the Flavor Physics and CP Violation Conference (FPCP 2007), Bled, Slovenia, 12-16 May 2007
ECONF C070512:021,2007
null
null
hep-ph
null
Recent developments for mixing and CP violation in the D0 and Bs systems are reviewed, including (i) the recently emerging evidence for D0-D0bar mixing and the interpretations of the measurements; (ii) the theoretical status of the calculations of Delta(Gamma_D) and Delta(m_D); (iii) some implications of the measurement of Bs mixing for new physics.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 18:35:11 GMT" } ]
2011-03-23T00:00:00
[ [ "Ligeti", "Zoltan", "" ] ]
0706.0920
Gabriel Menezes
G. Menezes and N. F. Svaiter
Stochastic Quantization of Scalar Fields in Einstein and Rindler Spacetime
null
J.Phys.A40:8545-8568,2007
10.1088/1751-8113/40/29/024
null
hep-th
null
We consider the stochastic quantization method for scalar fields defined in a curved manifold and also in a flat space-time with event horizon. The two-point function associated to a massive self-interacting scalar field is evaluated, up to the first order level in the coupling constant, for the case of an Einstein and also a Rindler Euclidean metric, respectively. Its value for the asymptotic limit of the Markov parameter is exhibited. The divergences therein are taken care of by employing a covariant stochastic regularization.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 21:40:43 GMT" } ]
2008-11-26T00:00:00
[ [ "Menezes", "G.", "" ], [ "Svaiter", "N. F.", "" ] ]
0706.0921
Brian Rider
Brian Rider, Xin Zhou
Janossy densities for Unitary ensembles at the spectral edge
6 figures, corrected typos, one erroneous corollary eliminated
null
null
null
math.PR math-ph math.MP
null
For a broad class of unitary ensembles of random matrices we demonstrate the universal nature of the Janossy densities of eigenvalues near the spectral edge, providing a different formulation of the probability distributions of the limiting second, third, etc. largest eigenvalues of the ensembles in question. The approach is based on a representation of the Janossy densities in terms of a system of orthogonal polynomials, plus the steepest descent method of Deift and Zhou for the asymptotic analysis of the associated Riemann-Hilbert problem.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 21:41:56 GMT" }, { "version": "v2", "created": "Tue, 8 Apr 2008 06:01:43 GMT" } ]
2008-04-08T00:00:00
[ [ "Rider", "Brian", "" ], [ "Zhou", "Xin", "" ] ]
0706.0922
Marina Stepanova
M. Stepanova, E. E. Antonova, J.M. Bosqued
Radial distribution of the inner magnetosphere plasma pressure using low-altitude satellite data during geomagnetic storm: the March 1-8, 1982 Event
Accepted in Advances in Space Research
null
10.1016/j.asr.2007.06.002
null
physics.space-ph physics.geo-ph
null
Plasma pressure distribution in the inner magnetosphere is one of the key parameters for understanding the main magnetospheric processes including geomagnetic storms and substorms. However, the pressure profiles obtained from in-situ particle measurements by the high-altitude satellites do not allow tracking the pressure variations related to the storms and substorms, because a time interval needed to do this generally exceeds the characteristic times of them. On contrary, fast movement of low-altitude satellites makes it possible to retrieve quasi-instantaneous profiles of plasma pressure along the satellite trajectory, using the fluxes of precipitating particles. For this study, we used the Aureol-3 satellite data for plasma pressure estimation, and the IGRF, Tsyganenko 2001 and Tsyganenko 2004 storm time geomagnetic field models for the pressure mapping into the equatorial plane. It was found that during quiet geomagnetic condition the radial pressure profiles obtained coincide with the profiles, obtained previously from the high-altitude measurements. On the contrary, it was found that during geomagnetic storm the plasma pressure profiles became sharper; the position of the maximum of plasma pressure corresponds to expected one for given Dst minimum; the maximum value of inner magnetosphere static pressure correlates with the solar wind dynamic pressure. Increase in the plasma pressure profiles indicates the possibility to consider the interchange instability as one of important factors for the development of the main phase of geomagnetic storm.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 21:45:23 GMT" } ]
2009-11-13T00:00:00
[ [ "Stepanova", "M.", "" ], [ "Antonova", "E. E.", "" ], [ "Bosqued", "J. M.", "" ] ]
0706.0923
Milton Ruiz
Milton Ruiz, Miguel Alcubierre, Dario Nunez
Regularization of spherical and axisymmetric evolution codes in numerical relativity
11 pages, 9 figures. Several changes. Main corrections are in eqs. (2.12) and (5.14). Accepted in Gen. Rel. Grav
Gen.Rel.Grav.40:159-182,2008
10.1007/s10714-007-0522-3
null
gr-qc
null
Several interesting astrophysical phenomena are symmetric with respect to the rotation axis, like the head-on collision of compact bodies, the collapse and/or accretion of fields with a large variety of geometries, or some forms of gravitational waves. Most current numerical relativity codes, however, can not take advantage of these symmetries due to the fact that singularities in the adapted coordinates, either at the origin or at the axis of symmetry, rapidly cause the simulation to crash. Because of this regularity problem it has become common practice to use full-blown Cartesian three-dimensional codes to simulate axi-symmetric systems. In this work we follow a recent idea idea of Rinne and Stewart and present a simple procedure to regularize the equations both in spherical and axi-symmetric spaces. We explicitly show the regularity of the evolution equations, describe the corresponding numerical code, and present several examples clearly showing the regularity of our evolutions.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 21:49:26 GMT" }, { "version": "v2", "created": "Tue, 11 Sep 2007 22:40:53 GMT" } ]
2008-11-26T00:00:00
[ [ "Ruiz", "Milton", "" ], [ "Alcubierre", "Miguel", "" ], [ "Nunez", "Dario", "" ] ]
0706.0924
Kaushik Bhattacharya
Utpal Roy, Suranjana Ghosh, Kaushik Bhattacharya
Some intricacies of the momentum operator in quantum mechanics
Minor corrections included. 9 pages, latex file. To be published in Revista Mexicana de Fisica
null
null
null
quant-ph hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In quantum mechanics textbooks the momentum operator is defined in the Cartesian coordinates and rarely the form of the momentum operator in spherical polar coordinates is discussed. Consequently one always generalizes the Cartesian prescription to other coordinates and falls in a trap. In this work we introduce the difficulties one faces when the question of the momentum operator in general curvilinear coordinates arises. We have tried to elucidate the points related to the definition of the momentum operator taking spherical polar coordinates as our specimen coordinate system and proposed an elementary method in which we can ascertain the form of the momentum operator in general coordinate systems.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 21:52:55 GMT" }, { "version": "v2", "created": "Tue, 23 Sep 2008 08:19:40 GMT" } ]
2008-09-23T00:00:00
[ [ "Roy", "Utpal", "" ], [ "Ghosh", "Suranjana", "" ], [ "Bhattacharya", "Kaushik", "" ] ]
0706.0925
Urs Hackstein
Urs Hackstein
Principal bundles on $p$-adic curves and parallel transport
null
null
null
null
math.AG
null
We define functorial isomorphisms of parallel transport along \'etale paths for a class of principal $G$-bundles on a $p$-adic curve. Here $G$ is a connected reductive algebraic group of finite presentation and the considered principal bundles are just those with potentially strongly semistable reduction of degree zero. The constructed isomorphisms yield continous functors from the \'etale fundamental groupoid of the given curve to the category of topological spaces with a simply transitive continous right $G(\mathbb{C}_{p})$-action. This generalizes a construction in the case of vector bundles on a $p$-adic curve by Deninger and Werner. It may be viewed as a partial $p$-adic analogue of the classical theory by Ramanathan of principal bundles on compact Riemann surfaces, which generalizes the classical Narasimhan--Seshadri theory of vector bundles on compact Riemann surfaces.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 22:14:40 GMT" } ]
2007-06-08T00:00:00
[ [ "Hackstein", "Urs", "" ] ]
0706.0926
Geralyn Zeller
MiniBooNE collaboration
Measurement of Muon Neutrino Quasi-Elastic Scattering on Carbon
5 pages, 3 figures
Phys.Rev.Lett.100:032301,2008
10.1103/PhysRevLett.100.032301
null
hep-ex nucl-ex
null
The observation of neutrino oscillations is clear evidence for physics beyond the standard model. To make precise measurements of this phenomenon, neutrino oscillation experiments, including MiniBooNE, require an accurate description of neutrino charged current quasi-elastic (CCQE) cross sections to predict signal samples. Using a high-statistics sample of muon neutrino CCQE events, MiniBooNE finds that a simple Fermi gas model, with appropriate adjustments, accurately characterizes the CCQE events observed in a carbon-based detector. The extracted parameters include an effective axial mass, M_A^eff = 1.23+/-0.20 GeV, that describes the four-momentum dependence of the axial-vector form factor of the nucleon; and a Pauli-suppression parameter, kappa = 1.019+/-0.011. Such a modified Fermi gas model may also be used by future accelerator-based experiments measuring neutrino oscillations on nuclear targets.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 19:13:54 GMT" }, { "version": "v2", "created": "Fri, 25 Jan 2008 20:24:00 GMT" } ]
2012-08-27T00:00:00
[ [ "MiniBooNE collaboration", "", "" ] ]
0706.0927
Barry Welsh
B.Y. Welsh, J. Edelstein, E. Korpela, et al
SPEAR far UV spectral imaging of highly ionized emission from the North Galactic Pole Region
5 figures
null
10.1051/0004-6361:20077685
null
astro-ph
null
We present far ultraviolet (FUV: 912 - 1750AA) spectral imaging observations recorded with the SPEAR satellite of the interstellar OVI (1032AA), CIV (1550AA), SiIV (1394AA), SiII* (1533AA) and AlII (1671AA) emission lines originating in a 60 x 30 degree rectangular region lying close to the North Galactic Pole. These data represent the first large area, moderate spatial resolution maps of the distribution of UV spectral-line emission originating the both the highly ionized medium (HIM) and the warm ionized medium (WIM) recorded at high galactic latitudes.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 23:16:41 GMT" } ]
2009-11-13T00:00:00
[ [ "Welsh", "B. Y.", "" ], [ "Edelstein", "J.", "" ], [ "Korpela", "E.", "" ] ]
0706.0928
Dinesh Singh
Dinesh Singh
An Analytic Perturbation Approach for Classical Spinning Particle Dynamics
14 pages, no figures; typo corrected in v3; accepted for publication in General Relativity and Gravitation as part of Bahram Mashhoon's 60th birthday festschrift
Gen.Rel.Grav.40:1179-1192,2008
10.1007/s10714-007-0597-x
null
gr-qc astro-ph
null
A perturbation method to analytically describe the dynamics of a classical spinning particle, based on the Mathisson-Papapetrou-Dixon (MPD) equations of motion, is presented. By a power series expansion with respect to the particle's spin magnitude, it is shown how to obtain in general form an analytic representation of the particle's kinematic and dynamical degrees of freedom that is formally applicable to infinite order in the expansion. Within this formalism, it is possible to identify a classical analogue of radiative corrections to the particle's mass and spin due to spin-gravity interaction. The robustness of this approach is demonstrated by showing how to explicitly compute the first-order momentum and spin tensor components for arbitrary particle motion in a general space-time background. Potentially interesting applications based on this perturbation approach are outlined.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 16:01:01 GMT" }, { "version": "v2", "created": "Wed, 18 Jul 2007 17:09:47 GMT" }, { "version": "v3", "created": "Thu, 10 Apr 2008 15:13:10 GMT" } ]
2008-11-26T00:00:00
[ [ "Singh", "Dinesh", "" ] ]
0706.0929
Paulo Tabuada
Paulo Tabuada
Controller synthesis for bisimulation equivalence
Added references, comments and examples
null
null
null
math.OC
null
The objective of this paper is to solve the controller synthesis problem for bisimulation equivalence in a wide variety of scenarios including discrete-event systems, nonlinear control systems, behavioral systems, hybrid systems and many others. This will be accomplished by showing that the arguments underlying proofs of existence and methods for the construction of controllers are extraneous to the particular class of systems being considered and thus can be presented in greater generality.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 23:36:20 GMT" }, { "version": "v2", "created": "Thu, 22 Nov 2007 20:28:45 GMT" } ]
2007-11-22T00:00:00
[ [ "Tabuada", "Paulo", "" ] ]
0706.0930
Boris Zhilyaev E
B.E. Zhilyaev
Gamma-Ray Bursts as Manifestation of Collisions of Primordial Black Holes with Stars
8 pages, 3 figures
Bull.Crim.Astrophys.Observ.103:58-64,2007
null
null
astro-ph
null
Using the BATSE survey data I find that quite small fraction of GRBs numbering 37 sources seems to emit the radiation similar to thermal bremsstrahlung in the range 20 to 300 keV. I suggest that these bursts may perhaps occur from collision of stars with primordial black holes (PBH). These objects are relic of a hot matter in the early Universe. PBH in the vicinity of stars may be found in consequence of incorporation processes during the formation of stars from interstellar clouds. At present they can form the gravitationally captured haloes around stars like the family of solar comets. The comet paradigm has been used to understand various aspects of PBH. Comet collisions with the Sun and planets are ordinary events in solar system history. On the analogy, one can support the view that PBH collisions with the parent star may be quite frequent events in its history, too. PBHs are the engines driving gamma-ray bursts when collide with the stars. Entering a stellar atmosphere, PBH is supposed to produce the gamma-ray burst due to accretion with duration from a few tenths of second to a few seconds. It can exhibit the main qualitative features of some GRBs. Their masses are estimated in the range from thousandths to hundredths of the solar mass. I found that these burst sources are isotropically distributed on the sky and are seen from a distance up to 50 ps. In this context one may expect that some short GRBs are observable signatures of primordial black holes in the Universe.
[ { "version": "v1", "created": "Wed, 6 Jun 2007 23:43:24 GMT" } ]
2009-06-25T00:00:00
[ [ "Zhilyaev", "B. E.", "" ] ]
0706.0931
E. Javier Elizondo
E. Javier Elizondo and Shun-Ichi Kimura
Irrationality of motivic series of Chow varieties
8 pages, ams-latex
null
null
null
math.AG
null
The Euler characteristic of all the Chow varieties, of a fixed projective variety, can be collected in a formal power series called the Euler-Chow series. This series coincides with the Hilbert series when the Picard group is a finite generated free abelian group. It is an interesting open problem to find for which varieties this series is rational. A few cases have been computed, and it is suspected that the series is not rational for the blow up of P^2 at nine points in general position. It is very natural to extend this series to Chow motives and ask the question if the series is rational or to find a counterexample. In this short paper we generalized the series and show by an example that the series is not rational. This opens the question of what is the geometrical meaning of the Euler-Chow series.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 00:28:35 GMT" } ]
2007-06-08T00:00:00
[ [ "Elizondo", "E. Javier", "" ], [ "Kimura", "Shun-Ichi", "" ] ]
0706.0932
Hirotaka Tamanoi
Hirotaka Tamanoi
Infinite Product Decomposition of Orbifold Mapping Spaces
Version 3: Two more references added and minor revision of introduction was made
Algebr. Geom. Topol. 9 (2009) 569-592
10.2140/agt.2009.9.569
null
math.AT
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Physicists showed that the generating function of orbifold elliptic genera of symmetric orbifolds can be written as an infinite product. We show that there exists a geometric factorization on space level behind this infinite product formula in much more general framework, where factors in the infinite product correspond to isomorphism classes of connected finite covering spaces of manifolds involved. From this formula, a concept of geometric Hecke operators for functors emerges. We show that these Hecke operators indeed satisfy the usual identity of Hecke operators for the case of 2-dimensional tori.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 00:40:48 GMT" }, { "version": "v2", "created": "Sun, 6 Apr 2008 03:27:55 GMT" }, { "version": "v3", "created": "Tue, 30 Sep 2008 00:15:54 GMT" } ]
2014-10-01T00:00:00
[ [ "Tamanoi", "Hirotaka", "" ] ]
0706.0933
W. Gilbert Clark
Guoqing Wu, W. G. Clark, S. E. Brown, J. S. Brooks, A. Kobayashi, H. Kobayashi
$^{77}$Se NMR measurements of the $\pi -d$ exchange field in the organic conductor $\lambda-$(BETS)$_{2}$FeCl$_{4}$
4 pages, 5 figures, submitted to Physical Review Letters
null
10.1103/PhysRevB.76.132510
null
cond-mat.str-el cond-mat.supr-con
null
$^{77}$Se-NMR spectrum and frequency shift measurements in the paramagnetic metal (PM) and antiferromagnetic insulating (AFI) phases are reported for a small single crystal of the organic conductor $\lambda-$(BETS)$_{2}$FeCl$_{4}$ as a function of temperature ($T$) and field alignment for an applied magnetic field $B_{0}$ = 9 T. The results show that in the low $T$ limit, where the localized Fe$^{3+}$ spins ($S_{d}$ = 5/2) are almost fully polarized, the conduction electrons (Se $\pi$-electrons, spin $s_{\pi}$ = 1/2) in the BETS molecules experience an exchange field ($\bf{B}$$_{\pi d}$) from the Fe$^{3+}$ spins with a value of $-$ 32.7 $\pm$ 1.5 T at 5 K and 9 T aligned opposite to $\bf{B}$$_{0}$. This large negative value of $\bf{B}$$_{\pi d}$ is consistent with that predicted by the resistivity measurements and supports the Jaccarino-Peter internal field-compensation mechanism being responsible for the origin of field-induced superconductivity.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 00:43:54 GMT" } ]
2009-11-13T00:00:00
[ [ "Wu", "Guoqing", "" ], [ "Clark", "W. G.", "" ], [ "Brown", "S. E.", "" ], [ "Brooks", "J. S.", "" ], [ "Kobayashi", "A.", "" ], [ "Kobayashi", "H.", "" ] ]
0706.0934
Hsi-Sheng Goan
Xiao-Zhong Yuan, Hsi-Sheng Goan and Ka-Di Zhu
Influence of an external magnetic field on the decoherence of a central spin coupled to an antiferromagnetic environment
29 preprint pages, 4 figures, to appear in New Journal of Physics
New J. Phys. 9 (2007) 219.
10.1088/1367-2630/9/7/219
null
cond-mat.other cond-mat.str-el quant-ph
null
Using the spin wave approximation, we study the decoherence dynamics of a central spin coupled to an antiferromagnetic environment under the application of an external global magnetic field. The external magnetic field affects the decoherence process through its effect on the antiferromagnetic environment. It is shown explicitly that the decoherence factor which displays a Gaussian decay with time depends on the strength of the external magnetic field and the crystal anisotropy field in the antiferromagnetic environment. When the values of the external magnetic field is increased to the critical field point at which the spin-flop transition (a first-order quantum phase transition) happens in the antiferromagnetic environment, the decoherence of the central spin reaches its highest point. This result is consistent with several recent quantum phase transition witness studies. The influences of the environmental temperature on the decoherence behavior of the central spin are also investigated.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 13:12:16 GMT" } ]
2009-11-13T00:00:00
[ [ "Yuan", "Xiao-Zhong", "" ], [ "Goan", "Hsi-Sheng", "" ], [ "Zhu", "Ka-Di", "" ] ]
0706.0935
Sun Fangwen
F. W. Sun, J. M. Cai, J. S. Xu, G. Chen, B. H. Liu, C. F. Li, Z. W. Zhou, G. C. Guo
Experimental Measurement of Multi-dimensional Entanglement via Equivalent Symmetric Projection
4 figures
PHYSICAL REVIEW A 76, 052303 (2007)
10.1103/PhysRevA.76.052303
null
quant-ph
null
We construct a linear optics measurement process to determine the entanglement measure, named \emph{I-concurrence}, of a set of $4 \times 4$ dimensional two-photon entangled pure states produced in the optical parametric down conversion process. In our experiment, an \emph{equivalent} symmetric projection for the two-fold copy of single subsystem (presented by L. Aolita and F. Mintert, Phys. Rev. Lett. \textbf{97}, 050501 (2006)) can be realized by observing the one-side two-photon coincidence without any triggering detection on the other subsystem. Here, for the first time, we realize the measurement for entanglement contained in bi-photon pure states by taking advantage of the indistinguishability and the bunching effect of photons. Our method can determine the \emph{I-concurrence} of generic high dimensional bipartite pure states produced in parametric down conversion process.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 00:47:54 GMT" }, { "version": "v2", "created": "Tue, 20 Nov 2007 15:17:17 GMT" } ]
2007-11-20T00:00:00
[ [ "Sun", "F. W.", "" ], [ "Cai", "J. M.", "" ], [ "Xu", "J. S.", "" ], [ "Chen", "G.", "" ], [ "Liu", "B. H.", "" ], [ "Li", "C. F.", "" ], [ "Zhou", "Z. W.", "" ], [ "Guo", "G. C.", "" ] ]
0706.0936
Redouane Mecheri
R. Mecheri, E. Marsch (Max Planck Institute for Solar System Research)
Ray tracing of ion-cyclotron waves in a coronal funnel
4 pages, 3 figures Modern Solar Facilities, Advanced Solar Science, Universitatsverlag Goettingen 2007
null
null
null
astro-ph
null
Remote observations of coronal holes have strongly implicated the kinetic interactions of ion-cyclotron waves with ions as a principal mechanism for plasma heating and acceleration of the fast solar wind. In order to study these waves, a linear perturbation analysis is used in the work frame of the collisionless multi-fluid model. We consider a non-uniform background plasma describing a funnel region and use the ray tracing equations to compute the ray path of the waves as well as the spatial variation of their properties.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 13:05:14 GMT" } ]
2007-06-08T00:00:00
[ [ "Mecheri", "R.", "", "Max Planck Institute for Solar System Research" ], [ "Marsch", "E.", "", "Max Planck Institute for Solar System Research" ] ]
0706.0937
Hirotaka Tamanoi
Hirotaka Tamanoi
Cap Products in String Topology
19 pages. Revised version 2 with added references, improved exposition, and simplified signs
Algebr. Geom. Topol. 9 (2009) 1201-1224
10.2140/agt.2009.9.1201
null
math.AT
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Chas and Sullivan showed that the homology of the free loop space LM of an oriented closed smooth finite dimensional manifold M admits the structure of a Batalin-Vilkovisky (BV) algebra equipped with an associative product called the loop product and a Lie bracket called the loop bracket. We show that the cap product is compatible with the above two products in the loop homology. Namely, the cap product with cohomology classes coming from M via the circle action acts as derivations on loop products as well as on loop brackets. We show that Poisson identities and Jacobi identities hold for the cap product action, extending the BV structure in the loop homology to the one including the cohomology of M. Finally, we describe the cap product in terms of the BV algebra structure in the loop homology.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 01:00:15 GMT" }, { "version": "v2", "created": "Fri, 11 Jul 2008 04:03:34 GMT" } ]
2014-10-01T00:00:00
[ [ "Tamanoi", "Hirotaka", "" ] ]
0706.0938
Zigao Dai
F. Y. Wang, Z. G. Dai, Zong-Hong Zhu
Measuring Dark Energy with Gamma-Ray Bursts and Other Cosmological Probes
28 pages, 13 figures, accepted for publication in ApJ. One reference added, one minor change in the final paragraph of section 1
Astrophys.J.667:1-10,2007
10.1086/520768
null
astro-ph
null
It has been widely shown that the cosmological parameters and dark energy can be constrained by using data from type-Ia supernovae (SNe Ia), the cosmic microwave background (CMB) anisotropy, the baryon acoustic oscillation (BAO) peak from Sloan Digital Sky Survey (SDSS), the X-ray gas mass fraction in clusters, and the linear growth rate of perturbations at z=0.15 as obtained from the 2dF Galaxy Redshift Survey. Recently, gamma-ray bursts (GRBs) have also been argued to be promising standard candles for cosmography. In this paper, we present constraints on the cosmological parameters and dark energy by combining a recent GRB sample including 69 events with the other cosmological probes. First, we find that for the LambdaCDM cosmology this combination makes the constraints stringent and the best fit is close to the flat universe. Second, we fit the flat Cardassian expansion model and find that this model is consistent with the LambdaCDM cosmology. Third, we present constraints on several two-parameter dark energy models and find that these models are also consistent with the LambdaCDM cosmology. Finally, we reconstruct the dark energy equation-of-state parameter w(z) and the deceleration parameter q(z). We see that the acceleration could have started at a redshift from z_T=0.40_{-0.08}^{+0.14} to z_T=0.65_{-0.05}^{+0.10}. This difference in the transition redshift is due to different dark energy models that we adopt. The most stringent constraint on w(z) lies in the redshift range z\sim 0.3-0.6.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 01:06:19 GMT" }, { "version": "v2", "created": "Tue, 26 Jun 2007 01:24:34 GMT" } ]
2009-06-23T00:00:00
[ [ "Wang", "F. Y.", "" ], [ "Dai", "Z. G.", "" ], [ "Zhu", "Zong-Hong", "" ] ]
0706.0939
Yusuke Wakabayashi
Y. Wakabayashi, M.H. Upton, S. Grenier, J.P. Hill, C.S. Nelson, J.-W. Kim, P.J. Ryan, A.I. Goldman, H. Zheng, and J.F. Mitchell
Surface effects on the orbital order in the single layered manganite La0.5Sr1.5MnO4
13 pages, 4 figures
Nature Materials 6, 972 - 976 (2007)
10.1038/nmat2061
null
cond-mat.str-el
null
We report the first observation of `orbital truncation rods' -- the scattering arising from the termination of bulk orbital order at the surface of a crystal. The x-ray measurements, performed on a cleaved, single-layered perovskite, La0.5Sr1.5MnO4, reveal that while the crystallographic surface is atomically smooth, the orbital `surface' is much rougher, with an r.m.s. deviation from the average `surface' of ~0.7nm. The temperature dependence of this scattering shows evidence of a surface-induced second order transition.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 02:01:09 GMT" } ]
2011-03-01T00:00:00
[ [ "Wakabayashi", "Y.", "" ], [ "Upton", "M. H.", "" ], [ "Grenier", "S.", "" ], [ "Hill", "J. P.", "" ], [ "Nelson", "C. S.", "" ], [ "Kim", "J. -W.", "" ], [ "Ryan", "P. J.", "" ], [ "Goldman", "A. I.", "" ], [ "Zheng", "H.", "" ], [ "Mitchell", "J. F.", "" ] ]
0706.0940
Alex Eskin
Alex Eskin, David Fisher and Kevin Whyte
Coarse differentiation of quasi-isometries II: Rigidity for Sol and Lamplighter groups
47 pages, 3 figures. Minor revisions addressing comments by the referee
null
null
null
math.GR math.GT math.MG
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, which is the continuation of [EFW2], we complete the proof of the quasi-isometric rigidity of Sol and the lamplighter groups. The results were announced in [EFW1].
[ { "version": "v1", "created": "Thu, 7 Jun 2007 02:19:38 GMT" }, { "version": "v2", "created": "Thu, 21 Jun 2012 23:13:47 GMT" } ]
2012-06-25T00:00:00
[ [ "Eskin", "Alex", "" ], [ "Fisher", "David", "" ], [ "Whyte", "Kevin", "" ] ]
0706.0941
Daowen Qiu
Lvzhou Li and Daowen Qiu
Local Entanglement Is Not Necessary for Perfect Discrimination between Unitary Operations Acting on Two-Qudits by LOCC
6 pages, 2 figures, we have added Lemma 5 and its proof, and some sentences have been modified and supplemented, as well
Physical Review A, 2008, 77(3): 032337 (7 pages).
10.1103/PhysRevA.77.032337
null
quant-ph
null
Recently, the problem of discriminating multipartite unitary operations by local operations and classical communication (LOCC) has attracted significant attention. The latest work in the literature on this problem showed that two multipartite unitary operations can always be perfectly distinguished by LOCC when a finite number of runs are allowable. However, in these schemes, local entanglement (an entangled state holden by one party) was required, which seems to imply that local entanglement is necessary for perfect discrimination between unitary operations by LOCC. In this article, we show that a perfect discrimination between two unitary operations acting on a two-qudits can always be achieved without exploiting any entanglement. As a result, we conclude that local entanglement is not necessary for perfect discrimination between unitary operations acting on two-qudits by LOCC.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 03:22:45 GMT" }, { "version": "v2", "created": "Mon, 11 Jun 2007 01:52:02 GMT" }, { "version": "v3", "created": "Wed, 5 Sep 2007 15:38:24 GMT" }, { "version": "v4", "created": "Sat, 8 Sep 2007 11:56:57 GMT" } ]
2015-05-13T00:00:00
[ [ "Li", "Lvzhou", "" ], [ "Qiu", "Daowen", "" ] ]
0706.0942
Balasubramanian Ananthanarayan
B. Ananthanarayan, Sunanda Banerjee, K. Shivaraj, A. Upadhyay
Puzzles of excited charm meson masses
9 pages, 1 figure, accepted for publication in Physics Letters B
Phys.Lett.B651:124-128,2007
10.1016/j.physletb.2007.06.013
null
hep-ph hep-ex
null
We attempt a comprehensive analysis of the low lying charm meson states which present several puzzles, including the poor determination of masses of several non-strange excited mesons. We use the well-determined masses of the ground states and the strange first excited states to `predict' the mass of the non-strange first excited state in the framework of heavy hadron chiral perturbation theory, an approach that is complementary to the well-known analysis of Mehen and Springer. This approach points to values for the masses of these states that are smaller than the experimental determinations. We provide a critical assessment of these mass measurements and point out the need for new experimental information.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 03:36:55 GMT" } ]
2008-11-26T00:00:00
[ [ "Ananthanarayan", "B.", "" ], [ "Banerjee", "Sunanda", "" ], [ "Shivaraj", "K.", "" ], [ "Upadhyay", "A.", "" ] ]
0706.0943
Angel Kumchev
Angel V Kumchev
On sums of primes from Beatty sequences
null
Integers 8 (2008), #A08
null
null
math.NT
null
Let $k \ge 2$ and $\alpha_1, \beta_1, ..., \alpha_k, \beta_k$ be reals such that the $\alpha_i$'s are irrational and greater than 1. Suppose further that some ratio $\alpha_i/\alpha_j$ is irrational. We study the representations of an integer $n$ in the form $$ p_1 + p_2 + ... + p_k = n, $$ where $p_i$ is a prime from the Beatty sequence $$ \mathcal B_i = \left\{n \in \mathbb N : n = [ \alpha_i m + \beta_i ] \text{for some} m \in \mathbb Z \right\}. $$
[ { "version": "v1", "created": "Thu, 7 Jun 2007 04:14:11 GMT" } ]
2010-08-23T00:00:00
[ [ "Kumchev", "Angel V", "" ] ]
0706.0944
Makoto Umeki Dr.
Makoto Umeki
Point Process Analysis of Vortices in a Periodic Box
7 pages, 14 figures, submitted to Proceedings of NCTAM Japan, Theoretical and Applied Mechanics Japan, Vol. 56 (2007)
null
null
null
physics.flu-dyn physics.data-an
null
The motion of assemblies of point vortices in a periodic parallelogram can be described by the complex position $z_j(t)$ whose time derivative is given by the sum of the complex velocities induced by other vortices and the solid rotation centered at $z_j$. A numerical simulation up to 100 vortices in a square periodic box is performed with various initial conditions, including single and double rows, uniform spacing, checkered pattern, and complete spatial randomness. Point process theory in spatial ecology is applied in order to quantify clustering of the distribution of vortices. In many cases, clustering of the distribution persists after a long time if the initial condition is clustered. In the case of positive and negative vortices with the same absolute value of strength, the $L$ function becomes positive for both types of vortices. Scattering or recoupling of pairs of vortices by a third vortex is remarkable.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 04:48:27 GMT" } ]
2007-06-08T00:00:00
[ [ "Umeki", "Makoto", "" ] ]
0706.0945
Jun-ichi Nakashima
Jun-ichi Nakashima (ASIAA/UIUC), Shuji Deguchi (Nobeyama Radio Obs.)
Correlation between Infrared Colors and Intensity Ratios of SiO Maser Lines
49 pages, 7 figures, 3 tables, accepted for publication in ApJ. Full resolution version available at http://www.asiaa.sinica.edu.tw/~junichi/paper/
null
10.1086/520825
null
astro-ph
null
We present the results of SiO millimeter-line observations of a sample of known SiO maser sources covering a wide dust-temperature range. A cold part of the sample was selected from the SiO maser sources found in our recent SiO maser survey of cold dusty objects. The aim of the present research is to investigate the causes of the correlation between infrared colors and SiO maser intensity ratios among different transition lines. In particular, the correlation between infrared colors and SiO maser intensity ratio among the J=1-0 v=1, 2, and 3 lines are mainly concerned in this paper. We observed in total 75 SiO maser sources with the Nobeyama 45m telescope quasi-simultaneously in the SiO J=1-0 v=0, 1, 2, 3, 4 and J=2-1 v=1, 2 lines. We also observed the sample in the 29SiO J=1-0 v=0 and J=2-1 v=0, and 30SiO J=1-0 v=0 lines, and the H2O 6(1,6)-5(2,3) line. As reported in previous papers, we confirmed that the intensity ratios of the SiO J=1-0 v=2 to v=1 lines clearly correlate with infrared colors. In addition, we found possible correlation between infrared colors and the intensity ratios of the SiO J=1-0 v=3 to v=1&2 lines. Two overlap lines of H2O (i.e., 11(6,6) nu_2=1 -> 12(7,5) nu_2=0 and 5(0,5) nu_2=2 -> 6(3,4) nu_2=1) might explain these correlation if these overlap lines become stronger with increase of infrared colors, although the phenomena also might be explained by more fundamental ways if we take into account the variation of opacity from object to object.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 04:48:57 GMT" } ]
2009-11-13T00:00:00
[ [ "Nakashima", "Jun-ichi", "", "ASIAA/UIUC" ], [ "Deguchi", "Shuji", "", "Nobeyama Radio Obs." ] ]
0706.0946
Masaaki Umehara
Yasuhiro Kurono and Masaaki Umehara
Flat Moebius strips of given isotopy types in R^3 whose centerlines are geodesics or lines of curvature
20pages, 12figures
null
null
null
math.DG
null
We construct real analytic flat Moebius strips of arbitrary isotopy types, whose centerlines are geodesics or lines of curvature.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 04:53:46 GMT" }, { "version": "v2", "created": "Fri, 17 Aug 2007 07:28:28 GMT" } ]
2011-11-10T00:00:00
[ [ "Kurono", "Yasuhiro", "" ], [ "Umehara", "Masaaki", "" ] ]
0706.0947
S. -R. Eric Yang
N.Y. Hwang, S.C. Kim, P.S. Park, and S.-R. Eric Yang
Pumping in quantum dots and non-Abelian matrix Berry phases
null
Solid State Commun. 145, 515 (2008) (Fast Track)
10.1016/j.ssc.2008.01.003
null
cond-mat.mes-hall quant-ph
null
We have investigated pumping in quantum dots from the perspective of non-Abelian (matrix) Berry phases by solving the time dependent Schr{\"o}dinger equation exactly for adiabatic changes. Our results demonstrate that a pumped charge is related to the presence of a finite matrix Berry phase. When consecutive adiabatic cycles are performed the pumped charge of each cycle is different from the previous ones.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 06:04:05 GMT" }, { "version": "v2", "created": "Thu, 14 Feb 2008 08:15:48 GMT" } ]
2009-11-13T00:00:00
[ [ "Hwang", "N. Y.", "" ], [ "Kim", "S. C.", "" ], [ "Park", "P. S.", "" ], [ "Yang", "S. -R. Eric", "" ] ]
0706.0948
Narendra Sahu
Narendra Sahu
TeV scale model for neutrino masses, dark matter and leptogenesis
4 pages, contribution to International workshop on theoretical high energy physics (IWTHEP), Roorkee, 2007
AIPConf.Proc.939:294-297,2007
10.1063/1.2803818
null
hep-ph
null
We present a TeV scale model for leptogenesis where the origin of neutrino masses are independent of the scale of leptogenesis. As a result, the model could be extended to explain {\it dark matter, neutrino masses and leptogenesis at the TeV scale}. The most attractive feature of this model is that it predicts a few hundred GeV triplet Higgs scalar that can be tested at LHC or ILC.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 06:25:39 GMT" } ]
2008-11-26T00:00:00
[ [ "Sahu", "Narendra", "" ] ]
0706.0949
Gautam Gangopadhyay
Madhubrata Bhattacharya and G. Gangopadhyay
Microscopic calculation of half lives of spherical proton emitters
null
Phys.Lett.B651:263-267,2007
10.1016/j.physletb.2007.06.012
null
nucl-th
null
Half life values for proton radioactivity in nuclei have been calculated in the WKB approximation. The microscopic proton-nucleus potential has been obtained by folding the densities of daughter nuclei with two microscopic NN interactions, DDM3Y and JLM. The densities have been obtained in the Relativistic Mean Field approach in the spherical approximation using the force FSU Gold. No substantial modification of results has been observed if other common forces are employed. The calculated results for the decays from the ground state or the low-lying excited states in almost all the nuclei agree well with experimental measurements. Reasons for large deviations in a few cases have been discussed. Results in $^{109}$I and $^{112,113}$Cs show that the effect of deformation is small contrary to earlier calculations. Predictions for possible proton radioactivity have been made in two nuclei, $^{93}$Ag and $^{97}$In.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 06:32:00 GMT" } ]
2008-11-26T00:00:00
[ [ "Bhattacharya", "Madhubrata", "" ], [ "Gangopadhyay", "G.", "" ] ]
0706.0950
Sami Dib
Sami Dib (1), Jongsoo Kim (1), Mohsen Shadmehri (2,3) ((1) KASI, (2) DCU, (3) Ferdowsi U.)
The Origin of the Arches Stellar Cluster Mass Function
5 pages, 2 figures, accepted to MNRAS Letters
null
10.1111/j.1745-3933.2007.00362.x
null
astro-ph
null
We investigate the time evolution of the mass distribution of pre-stellar cores (PSCs) and their transition to the initial stellar mass function (IMF) in the central parts of a molecular cloud (MC) under the assumption that the coalescence of cores is important. Our aim is to explain the observed shallow IMF in dense stellar clusters such as the Arches cluster. The initial distributions of PSCs at various distances from the MC center are those of gravitationally unstable cores resulting from the gravo-turbulent fragmentation of the MC. As time evolves, there is a competition between the PSCs rates of coalescence and collapse. Whenever the local rate of collapse is larger than the rate of coalescence in a given mass bin, cores are collapsed into stars. With appropriate parameters, we find that the coalescence-collapse model reproduces very well all the observed characteristics of the Arches stellar cluster IMF; Namely, the slopes at high and low mass ends and the peculiar bump observed at ~5-6 M_sol. Our results suggest that today's IMF of the Arches cluster is very similar to the primordial one and is prior to the dynamical effects of mass segregation becoming important
[ { "version": "v1", "created": "Thu, 7 Jun 2007 06:52:14 GMT" }, { "version": "v2", "created": "Sun, 15 Jul 2007 05:05:40 GMT" } ]
2009-11-13T00:00:00
[ [ "Dib", "Sami", "" ], [ "Kim", "Jongsoo", "" ], [ "Shadmehri", "Mohsen", "" ] ]
0706.0951
Werner Vogel
Werner Vogel
Nonclassical correlation properties of radiation fields
shortened version, 4 pages
Phys. Rev. Lett. 100, 013605 (2008)
10.1103/PhysRevLett.100.013605
null
quant-ph
null
A full characterization of nonclassical space-time dependent correlations of radiation is formulated in terms of normally and time-ordered field correlation functions. It describes not only the properties of initially prepared multimode radiation fields, but also the dynamics of radiation sources. Some of these correlation effects occur in the resonance fluorescence of a single two-level atom.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 06:57:32 GMT" }, { "version": "v2", "created": "Sat, 12 Jan 2008 13:10:56 GMT" } ]
2009-11-13T00:00:00
[ [ "Vogel", "Werner", "" ] ]
0706.0952
Shuichiro Takeda
Wee Teck Gan, Shuichiro Takeda
The Local Langlands Conjecture for GSp(4)
null
null
null
null
math.NT math.RT
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We prove the local Langlands conjecture for $GSp_4(F)$ where $F$ is a non-archimedean local field of characteristic zero.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 07:01:26 GMT" }, { "version": "v2", "created": "Mon, 2 Jul 2007 03:48:37 GMT" }, { "version": "v3", "created": "Sat, 27 Oct 2007 11:15:49 GMT" }, { "version": "v4", "created": "Thu, 17 Jun 2010 19:07:52 GMT" } ]
2010-06-18T00:00:00
[ [ "Gan", "Wee Teck", "" ], [ "Takeda", "Shuichiro", "" ] ]
0706.0953
Anjan Joshipura
Anjan S. Joshipura and Bhavik P. Kodrani
Complex CKM matrix, spontaneous CP violation and generalized $\mu$-$\tau$ symmetry
8 pages, 2 figures
Phys.Lett.B670:369-373,2009
10.1016/j.physletb.2008.11.007
null
hep-ph
null
The multi-Higgs models having spontaneous CP violation (SPCV) and natural flavor conservation (NFC) lead to a real CKM matrix $V$ contradicting current evidence in favour of a complex $V$. This contradiction can be removed by using a generalized $\mu$-$\tau$ (called 23) symmetry in place of the discrete symmetry conventionally used to obtain NFC. If 23 symmetry is exact then the Higgs induced flavour changing neutral currents (FCNC) vanish as in case of NFC. 23 breaking introduces SPCV, a phase in $V$ and suppressed FCNC among quarks. The FCNC couplings $F_{ij}^{d,u}$ between $i$ and $j$ generations show a hierarchy $|F_{12}^{d,u}|<|F_{13}^{d,u}|<|F_{23}^{d,u}|$ with the result that the FCNC can have observable consequences in $B$ mixing without conflicting with the $K^0-\bar{K}^0$ mixing. Detailed fits to the quark masses and the CKM matrix are used to obtain the (complex) couplings $F_{ij}^d$ and $F_{ij}^u$. Combined constraints from flavour and CP violations in the $K,B_d,B_s,D$ mesons are analyzed within the model. They allow ($i$) relatively light Higgs, 100-150 GeV ($ii$) measurable extra contributions to the magnitudes and phases of the $B^0_{d,s}-\bar{B}^0_{d,s}$ mixing amplitudes and ($iii$) the $D^0-\bar{D}^0$ mixing at the current sensitivity level.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 07:07:13 GMT" } ]
2009-01-16T00:00:00
[ [ "Joshipura", "Anjan S.", "" ], [ "Kodrani", "Bhavik P.", "" ] ]
0706.0954
Krzysztof Fr{\ka}czek
Krzysztof Fraczek, Leonid Polterovich
Growth and mixing
To appear in Journal of Modern Dynamics
null
null
null
math.DS
null
Given a bi-Lipschitz measure-preserving homeomorphism of a compact metric measure space of finite dimension, consider the sequence formed by the Lipschitz norms of its iterations. We obtain lower bounds on the growth rate of this sequence assuming that our homeomorphism mixes a Lipschitz function. In particular, we get a universal lower bound which depends on the dimension of the space but not on the rate of mixing. Furthermore, we get a lower bound on the growth rate in the case of rapid mixing. The latter turns out to be sharp: the corresponding example is given by a symbolic dynamical system associated to the Rudin-Shapiro sequence.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 07:08:55 GMT" }, { "version": "v2", "created": "Thu, 8 Nov 2007 11:44:59 GMT" } ]
2009-01-13T00:00:00
[ [ "Fraczek", "Krzysztof", "" ], [ "Polterovich", "Leonid", "" ] ]
0706.0955
Christoph Haefeli
Jurg Gasser, Christoph Haefeli, Mikhail A. Ivanov, Martin Schmid
Integrating out strange quarks in ChPT
14 pages, 3 figures, References added. Due to a typo in a form program, we missed a finite, scale independent part in l_7. Is now included. Version to appear in Phys.Lett.B
Phys.Lett.B652:21-26,2007
10.1016/j.physletb.2007.06.058
null
hep-ph
null
We study three flavour chiral perturbation theory in a limit where the strange quark mass is much larger than the external momenta and the up and down quark masses, and where the external fields are those of two-flavour chiral perturbation theory. In this case, the theory reduces to the one of SU(2)_L x SU(2)_R. Through this reduction, one can work out the strange quark mass dependence of the LECs in the two-flavour case. We present the pertinent relations at two-loop order for F,B and l_i.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 07:29:41 GMT" }, { "version": "v2", "created": "Tue, 26 Jun 2007 12:37:34 GMT" } ]
2008-11-26T00:00:00
[ [ "Gasser", "Jurg", "" ], [ "Haefeli", "Christoph", "" ], [ "Ivanov", "Mikhail A.", "" ], [ "Schmid", "Martin", "" ] ]
0706.0956
Mais Suleymanov
M. K. Suleymanov, E. U. Khan, K. Ahmed, Mahnaz Q. Haseeb, Farida Tahir and Y. H. Huseynaliyev
Search for deconfinement in the cluster at ultrarelativistic heavy ion collisions
two pages and one figure
Nucl.Phys.Proc.Suppl.177-178:341-342,2008
10.1016/j.nuclphysbps.2007.11.154
null
nucl-ex
null
Some of the centrality experiments indicate regime change and saturation in the behavior of characteristics of the secondary particles. It is observed as a critical phenomenon for hadron-nuclear, nuclear-nuclear interactions and ultrarelativistic heavy ion collisions. The existing simple models do not explain the effect. We believe that the responsible mechanism to explain the phenomena could be the percolation cluster formation and expect appearance of deconfinement in the cluster.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 07:33:00 GMT" } ]
2008-11-26T00:00:00
[ [ "Suleymanov", "M. K.", "" ], [ "Khan", "E. U.", "" ], [ "Ahmed", "K.", "" ], [ "Haseeb", "Mahnaz Q.", "" ], [ "Tahir", "Farida", "" ], [ "Huseynaliyev", "Y. H.", "" ] ]
0706.0957
Jim Howie
Dylan Bowden and James Howie
Winding numbers and SU(2)-representations of knot groups
13 pages, 2 figures
null
null
null
math.GT math.GR
null
Given an abelian group $A$ and a Lie group $G$, we construct a bilinear pairing from $A\times\pi_1({\mathcal R})$ to $\pi_1(G)$, where $\mathcal R$ is a subvariety of the variety of representations $A\to G$. In the case where $A$ is the peripheral subgroup of a torus or two-bridge knot group, $G=S^1$ and $\mathcal R$ is a certain variety of representations arising from suitable SU(2)-representations of the knot group, we show that this pairing is not identically zero. We discuss the consequences of this result for the SU(2)-representations of fundamental groups of manifolds obtained by Dehn surgery on such knots.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 07:38:31 GMT" } ]
2007-06-08T00:00:00
[ [ "Bowden", "Dylan", "" ], [ "Howie", "James", "" ] ]
0706.0958
Kazuo Tsushima
M. Angeles Perez-Garcia, K. Tsushima, A. Valcarce
Simulation of symmetric nuclei and the role of Pauli potential in binding energies and radii
19 pages, 12 figures
Int.J.Mod.Phys.E18:705-719,2009
null
null
nucl-th nucl-ex
null
It is shown that the use of a density dependent effective Pauli potential together with a nucleon-nucleon interaction potential plays a crucial role to reproduce not only the binding energies but also the matter root mean square radii of medium mass range spin-isospin saturated nuclei. This study is performed with a semiclassical Monte Carlo many-body simulation within the context of a simplified nucleon-nucleon interaction to focus on the effect of the genuine correlations due to the fermionic nature of nucleons. The procedure obtained is rather robust and it does not depend on the detailed features of the nucleon-nucleon interaction. For nuclei below saturation the density dependence may be represented in terms either of the nucleon number, $A$, or the associated Fermi momenta. When testing the simulation procedure for idealized "infinite" symmetric nuclear matter within the corresponding range of densities, it turns out that finite size effects affect the Pauli potential strength parametrization in systems up to about 120 particles while remaining approximately stable for larger systems.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 08:01:39 GMT" }, { "version": "v2", "created": "Mon, 17 Mar 2008 10:52:02 GMT" } ]
2009-05-13T00:00:00
[ [ "Perez-Garcia", "M. Angeles", "" ], [ "Tsushima", "K.", "" ], [ "Valcarce", "A.", "" ] ]
0706.0959
Keita Kobayashi
K.Kobayashi, M.Mine, M.Okumura and Y.Yamanaka
Quantum Field Theoretical Analysis on Unstable Behavior of Bose-Einstein Condensates in Optical Lattices
16pages, 4figures
null
10.1016/j.aop.2007.09.002
null
cond-mat.other
null
We study the dynamics of Bose-Einstein condensates flowing in optical lattices on the basis of quantum field theory. For such a system, a Bose-Einstein condensate shows a unstable behavior which is called the dynamical instability. The unstable system is characterized by the appearance of modes with complex eigenvalues. Expanding the field operator in terms of excitation modes including complex ones, we attempt to diagonalize the unperturbative Hamiltonian and to find its eigenstates. It turns out that although the unperturbed Hamiltonian is not diagonalizable in the conventional bosonic representation the appropriate choice of physical states leads to a consistent formulation. Then we analyze the dynamics of the system in the regime of the linear response theory. Its numerical results are consitent with as those given by the discrete nonlinear Schrodinger equation.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:36:01 GMT" } ]
2009-11-13T00:00:00
[ [ "Kobayashi", "K.", "" ], [ "Mine", "M.", "" ], [ "Okumura", "M.", "" ], [ "Yamanaka", "Y.", "" ] ]
0706.0960
Yassir Dinar ibrahim
Yassir Ibrahim Dinar
On classification and construction of algebraic Frobenius manifolds
20 pages
null
10.1016/j.geomphys.2008.04.001
null
nlin.SI
null
We develop the theory of generalized bi-Hamiltonian reduction. Applying this theory to a suitable loop algebra we recover a generalized Drinfeld-Sokolov reduction. This gives a way to construct new examples of algebraic Frobenius manifolds.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 07:48:14 GMT" }, { "version": "v2", "created": "Mon, 22 Oct 2007 16:36:38 GMT" }, { "version": "v3", "created": "Thu, 27 Mar 2008 10:22:01 GMT" } ]
2009-11-13T00:00:00
[ [ "Dinar", "Yassir Ibrahim", "" ] ]
0706.0961
Leif Svalgaard
Leif Svalgaard, Edward W. Cliver
The InterHourly-Variability (IHV) Index of Geomagnetic Activity and its Use in Deriving the Long-term Variation of Solar Wind Speed
null
null
10.1029/2007JA012437
null
astro-ph
null
We describe the derivation of the InterHourly Variability (IHV) index of geomagnetic activity. The IHV-index for a geomagnetic element is mechanically derived from hourly values as the sum of the unsigned differences between adjacent hours over a seven-hour interval centered on local midnight. The index is derived separately for stations in both hemispheres within six longitude sectors using only local night hours. It is intended as a long-term index. Available data allows derivation of the index back well into the 19th century. On a time scale of a 27-day Bartels rotation, IHV averages for stations with corrected geomagnetic latitude less than 55 degrees are strongly correlated with midlatitude range indices. Assuming a constant calibration of the aa-index we find that observed yearly values of aa before the year 1957 are 2.9 nT too small compared to values calculated from IHV using the regression constants based on 1980-2004. We interpret this discrepancy as an indication that the calibration of the aa index is in error before 1957. There is no such problem with the ap index. Rotation averages of IHV are also strongly correlated with solar wind parameters (BV^2). On a time scale of a year combining the IHV-index and the recently-developed Inter-Diurnal Variability (IDV) index (giving B) allows determination of solar wind speed, V, from 1890-present. Over the ~120-year series, the yearly mean solar wind speed varied from a low of 303 km/s in 1902 to a high value of 545 km/s in 2003. The calculated yearly values of the product BV using B and V separately derived from IDV and IHV agree quantitatively with (completely independent) BV derived from the amplitude of the diurnal variation of the H component in the polar caps since 1926 and sporadically beyond.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 19:57:01 GMT" } ]
2015-05-13T00:00:00
[ [ "Svalgaard", "Leif", "" ], [ "Cliver", "Edward W.", "" ] ]
0706.0962
Vinod Chandra
Vinod Chandra, Ravindra Kumar
Chromo-electric Yang-Mills gauge fields
6 pages, abstract modified, revised version
null
null
null
hep-th
null
We obtain static gauge field configurations for SU(2) Yang-Mills gauge theory in the absence of chromo-magnetic field. We also present a systematic way to obtain such configurations for SU(3) and SU(4) YM gauge theories by realizing their Lie algebras in terms of SU(2). Generalization of our method to SU(N) gauge theory with N>2 is straight forward. The gauge fields thus obtained are complex. We investigated the issue of uniform as well as real chromo-electric field with these configurations. Furthermore, we investigated the possible class of vacuum solutions for the gauge fields and found that they are gauge inequivalent to the usual vacuum configuration $A^a_{\mu}=0$.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 08:07:24 GMT" }, { "version": "v2", "created": "Sat, 21 Jul 2007 17:26:25 GMT" } ]
2007-07-23T00:00:00
[ [ "Chandra", "Vinod", "" ], [ "Kumar", "Ravindra", "" ] ]
0706.0963
A. V. Luchinsky
S. S. Gershtein, A. K. Likhoded
c-quark decay modes in B_c-meson
6 pages, 1 table; refrences added
null
null
null
hep-ph hep-ex
null
We discuss the possibility for observing $B_c$ mesons in decay channels with $B_s$ in final state.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 08:14:28 GMT" }, { "version": "v2", "created": "Wed, 13 Jun 2007 08:56:46 GMT" } ]
2007-06-18T00:00:00
[ [ "Gershtein", "S. S.", "" ], [ "Likhoded", "A. K.", "" ] ]
0706.0964
Elisa Ercolessi
S. Chaturvedi, E. Ercolessi, G. Marmo, G. Morandi, N. Mukunda, R. Simon
Ray space Riccati evolution and geometric phases for N-level quantum systems
14 pages
Pramana69:317-328,2007
10.1007/s12043-007-0135-0
null
quant-ph
null
We present a simple derivation of the matrix Riccati equations governing the reduced dynamics as one descends from the group U(N) describing the Schroedinger evolution of an N-level quantum system to the various coset spaces, Grassmanian manifolds, associated with it. The special case pertaining to the geometric phase in N-level systems is described in detail. Further, we show how the matrix Riccati equation thus obtained can be reformulated as an equation describing Hamiltonian evolution in a classical phase space and establish correspondences between the two descriptions.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 08:34:24 GMT" } ]
2008-11-26T00:00:00
[ [ "Chaturvedi", "S.", "" ], [ "Ercolessi", "E.", "" ], [ "Marmo", "G.", "" ], [ "Morandi", "G.", "" ], [ "Mukunda", "N.", "" ], [ "Simon", "R.", "" ] ]
0706.0965
Prasad Subramanian Dr
K. A. P. Singh, Prasad Subramanian
An evaluation of possible mechanisms for anomalous resistivity in the solar corona
Accepted, Solar Physics
null
10.1007/s11207-007-0464-7
null
astro-ph
null
A wide variety of transient events in the solar corona seem to require explanations that invoke fast reconnection. Theoretical models explaining fast reconnection often rely on enhanced resistivity. We start with data derived from observed reconnection rates in solar flares and seek to reconcile them with the chaos-induced resistivity model of Numata & Yoshida (2002) and with resistivity arising out of the kinetic Alfv\'en wave (KAW) instability. We find that the resistivities arising from either of these mechanisms, when localized over lengthscales of the order of an ion skin depth, are capable of explaining the observationally mandated Lundquist numbers.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 11:57:20 GMT" } ]
2009-11-13T00:00:00
[ [ "Singh", "K. A. P.", "" ], [ "Subramanian", "Prasad", "" ] ]
0706.0966
Hiroyuki Sagawa
Hiroyuki Sagawa, Satoshi Yoshida, Guo-Mo Zeng, Jian-Zhong Gu, Xi-Zhen Zhang
Isospin dependence of incompressibility in relativistic and non-relativistic mean field calculations
19pages,5figures
Phys.Rev.C76:034327,2007; Erratum-ibid.C77:049902,2008
10.1103/PhysRevC.76.034327 10.1103/PhysRevC.77.049902
null
nucl-th
null
The isospin dependence of incompressibility is investigated in the Skyrme Hartree-Fock (SHF) and relativistic mean field (RMF) models. The correlations between the nuclear matter incompressibility and the isospin dependent term of the finite nucleus incompressibility is elucidated by using the Thomas-Fermi approximation. The Coulomb term is also studied by using various different Skyrme Hamiltonians and RMF Lagrangians. The symmetry energy coefficient of incompressibility is extracted to be K_{\tau}=-(500\pm50) MeV from the recent experimental data of isoscalar giant monopole resonances (ISGMR) in Sn isotopes. Microscopic HF+random phase approximation (RPA) calculations are also performed with Skyrme interactions for ^{208}Pb and Sn isotopes to study the strength distributions of ISGMR. .
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:05:24 GMT" } ]
2014-11-18T00:00:00
[ [ "Sagawa", "Hiroyuki", "" ], [ "Yoshida", "Satoshi", "" ], [ "Zeng", "Guo-Mo", "" ], [ "Gu", "Jian-Zhong", "" ], [ "Zhang", "Xi-Zhen", "" ] ]
0706.0967
Marek Czachor
Marek Czachor
Elementary gates for cartoon computation
Published version
J. Phys. A: Math. Theor. 40 (2007) F753-F759
10.1088/1751-8113/40/31/F01
null
quant-ph
null
The basic one-bit gates (X, Y, Z, Hadamard, phase, pi/8) as well as the controlled cnot and Toffoli gates are reformulated in the language of geometric-algebra quantum-like computation. Thus, all the quantum algorithms can be reformulated in purely geometric terms without any need of tensor products.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:09:31 GMT" }, { "version": "v2", "created": "Sat, 9 Jun 2007 08:56:55 GMT" }, { "version": "v3", "created": "Thu, 19 Jul 2007 11:45:12 GMT" } ]
2007-07-19T00:00:00
[ [ "Czachor", "Marek", "" ] ]
0706.0968
Valeriu Moldoveanu
Valeriu Moldoveanu, Vidar Gudmundsson, Andrei Manolescu
Non-adiabatic transport in a quantum dot turnstile
10 pages. 8 figures
PRB 76, 165308 (2007).
10.1103/PhysRevB.76.165308
null
cond-mat.mes-hall
null
We present a theoretical study of the electronic transport through a many-level quantum dot driven by time-dependent signals applied at the contacts to the leads. If the barriers oscillate out of phase the system operates like a turnstile pump under a finite constant bias, as observed in the experiments of Kouwenhoven {\it et al.} [Phys. Rev. Lett. {\bf 67}, 1626 (1991)]. The time-dependent currents and their averages over succesive pumping periods are computed from the Keldysh formalism for tight-binding models. The calculation considers a sudden application of the pumping potentials at $t=0$ which leads to transient features of the time-dependent and averaged currents during the first pumping cycles which turn out to be important in the high-frequency regime. We show that in the transient regime the efficiency of the system as a pump is rather poor because it mainly absorbs charge from both leads in order to fill the levels located below the bias window. Under a finite bias and a low-frequency pumping signal the charge transferred across the system depends on the number of levels located within the bias window. The internal charge dynamics and the role of energy sidebands are investigated. The so called satellite peaks of the averaged current are observed also in the transient regime.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:13:46 GMT" } ]
2009-11-13T00:00:00
[ [ "Moldoveanu", "Valeriu", "" ], [ "Gudmundsson", "Vidar", "" ], [ "Manolescu", "Andrei", "" ] ]
0706.0969
Samuel Alexandre Vidal
Samuel Alexandre Vidal
An Optimal Algorithm to Generate Pointed Trivalent Diagrams and Pointed Triangular Maps
29 pages, over 140 drawings
Theoretical Computer Science Volume 411, Issues 31-33, 28 June 2010, Pages 2945-2967
null
null
math.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A trivalent diagram is a connected, two-colored bipartite graph (parallel edges allowed but not loops) such that every black vertex is of degree 1 or 3 and every white vertex is of degree 1 or 2, with a cyclic order imposed on every set of edges incident to to a same vertex. A rooted trivalent diagram is a trivalent diagram with a distinguished edge, its root. We shall describe and analyze an algorithm giving an exhaustive list of rooted trivalent diagrams of a given size (number of edges), the list being non-redundant in that no two diagrams of the list are isomorphic. The algorithm will be shown to have optimal performance in that the time necessary to generate a diagram will be seen to be bounded in the amortized sense, the bound being independent of the size of the diagrams. That's what we call the CAT property. One objective of the paper is to provide a reusable theoretical framework for algorithms generating exhaustive lists of complex combinatorial structures with attention paid to the case of unlabeled structures and to those generators having the CAT property.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:18:11 GMT" }, { "version": "v2", "created": "Fri, 6 Jul 2007 11:24:24 GMT" }, { "version": "v3", "created": "Fri, 27 Feb 2009 14:42:50 GMT" } ]
2012-01-31T00:00:00
[ [ "Vidal", "Samuel Alexandre", "" ] ]
0706.0970
Thomas Willwacher
Thomas Willwacher
A Counterexample to the Quantizability of Modules
null
Lett. Math. Phys. 81 (2007), no. 3, pp. 265--280
10.1007/s11005-007-0179-6
null
math.SG math.QA
null
Let a Poisson structure on a manifold M be given. If it vanishes at a point m, the evaluation at m defines a one dimensional representation of the Poisson algebra of functions on M. We show that this representation can, in general, not be quantized. Precisely, we give a counterexample for M=R^n, such that: (i) The evaluation map at 0 can not be quantized to a representation of the algebra of functions with product the Kontsevich product associated to the Poisson structure. (ii) For any formal Poisson structure extending the given one and vanishing at zero up to second order in epsilon, (i) still holds. We do not know whether the second claim remains true if one allows the higher order terms in epsilon to attain nonzero values at zero.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 10:23:59 GMT" }, { "version": "v2", "created": "Thu, 21 Jun 2007 07:38:28 GMT" }, { "version": "v3", "created": "Tue, 17 Jul 2007 13:27:37 GMT" } ]
2014-01-16T00:00:00
[ [ "Willwacher", "Thomas", "" ] ]
0706.0971
Yuichi Kabaya
Yuichi Kabaya
A method to find ideal points from ideal triangulations
14 pages; revised version
null
null
null
math.GT
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We give a simple method to find ideal points of the character variety of a 3-manifold from an ideal triangulation.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:23:13 GMT" }, { "version": "v2", "created": "Mon, 8 Sep 2008 16:58:09 GMT" } ]
2008-09-08T00:00:00
[ [ "Kabaya", "Yuichi", "" ] ]
0706.0972
H\'el\`ene Esnault
H\'el\`ene Esnault and Chenyang Xu
Congruence for rational points over finite fields and coniveau over local fields
8 pages
null
null
null
math.NT math.AG
null
If the $\ell$-adic cohomology of a projective smooth variety, defined over a local field $K$ with finite residue field $k$, is supported in codimension $\ge 1$, then every model over the ring of integers of $K$ has a $k$-rational point. For $K$ a $p$-adic field, this is math/0405318, Theorem 1.1. If the model $\sX$ is regular, one has a congruence $|\sX(k)|\equiv 1 $ modulo $|k|$ for the number of $k$-rational points 0704.1273, Theorem 1.1. The congruence is violated if one drops the regularity assumption.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:23:23 GMT" } ]
2007-06-08T00:00:00
[ [ "Esnault", "Hélène", "" ], [ "Xu", "Chenyang", "" ] ]
0706.0973
Kotaro Yamada
Shoichi Fujimori, Wayne Rossman, Masaaki Umehara, Kotaro Yamada, Seong-Deog Yang
Spacelike mean curvature one surfaces in de Sitter 3-space
32 pages, 3 figures
Comm. Anal. Geom. 17(3) (2009), 383-427
null
null
math.DG
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The first author studied spacelike constant mean curvature one (CMC-1) surfaces in de Sitter 3-space when the surfaces have no singularities except within some compact subset and are of finite total curvature on the complement of this compact subset. However, there are many CMC-1 surfaces whose singular sets are not compact. In fact, such examples have already appeared in the construction of trinoids given by Lee and the last author via hypergeometric functions. In this paper, we improve the Osserman-type inequality given by the first author. Moreover, we shall develop a fundamental framework that allows the singular set to be non-compact, and then will use it to investigate the global behavior of CMC-1 surfaces.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:24:25 GMT" }, { "version": "v2", "created": "Fri, 8 Jun 2007 02:30:04 GMT" }, { "version": "v3", "created": "Mon, 4 May 2009 19:09:45 GMT" } ]
2009-12-25T00:00:00
[ [ "Fujimori", "Shoichi", "" ], [ "Rossman", "Wayne", "" ], [ "Umehara", "Masaaki", "" ], [ "Yamada", "Kotaro", "" ], [ "Yang", "Seong-Deog", "" ] ]
0706.0974
Tomi Koivisto
Tomi Koivisto
Viable Palatini-f(R) cosmologies with generalized dark matter
5 pages, no figures; To appear in PRD. V2: Typos in the appendix corrected
Phys.Rev.D76:043527,2007
10.1103/PhysRevD.76.043527
null
astro-ph
null
We study the formation of large-scale structure in universes dominated by dark matter and driven to accelerated expansion by f(R) gravity in the Palatini formalism. If the dark matter is cold, practically all of these models are ruled out because they fail to reproduce the observed matter power spectrum. We point out that if the assumption that dark matter is perfect and pressureless at all scales is relaxed, nontrivial alternatives to a cosmological constant become viable within this class of modified gravity models.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:33:16 GMT" }, { "version": "v2", "created": "Tue, 19 Feb 2008 17:52:59 GMT" } ]
2008-11-26T00:00:00
[ [ "Koivisto", "Tomi", "" ] ]
0706.0975
Israfil Guseinov
I. I. Guseinov
Combined Extended Rejoinder to "Extended Comment on "One-Range Addition Theorems for Coulomb Interaction Potential and Its Derivatives" by I. I. Guseinov (Chem. Phys., Vol. 309 (2005), pp. 209-213)"
According to arXiv moderation's suggestion, our reply to published by E.J.Weniger "arXiv:0707.3361v1" has been combined with recently published my Rejoinder "arXiv: 0706.0975v2", 36 pages, title slightly changed, minor changes in the Sections 3 and 4, new references has been added
null
null
null
physics.chem-ph physics.comp-ph
null
This article is a thorough critique to the Weniger's comments made to our papers published in prestigious journals in the recent years. A detailed and critical examination of the arguments that led to the suggested comment by Weniger reveals some serious flaws. In our published papers we have shown that the unsymmetrical and symmetrical one-range addition theorems for Slater type orbitals, Coulomb-Yukawa like correlated interaction potentials (CIPs) and their derivatives are derived from the expansions in terms of -ETOs that are complete and orthonormal sets of exponential type orbitals in corresponding Hilbert spaces, where The concrete criticism raised in Weniger's comment against our papers actually touches a very minor aspect of the works that are not relevant at all for the conclusions, which are made. As can be seen from our papers, all of the formulas for different kinds of multicenter integrals over Slater type orbitals with integer and noninteger principal quantum numbers obtained by the use of unsymmetrical and symmetrical one-range addition theorems were tested by computer calculations. We reject the Weniger's personal views about papers published by Guseinov and his coworkers from 1978 to 2006 and respectable referees on one-range addition theorems and multicenter integrals. All claims of inconsistencies and flaws in the theoretical framework are rejected as unfounded. This rejoinder paper contains all of the answers to Weniger's comments.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:38:39 GMT" }, { "version": "v2", "created": "Fri, 6 Jul 2007 09:26:53 GMT" }, { "version": "v3", "created": "Fri, 24 Aug 2007 09:41:13 GMT" } ]
2011-11-10T00:00:00
[ [ "Guseinov", "I. I.", "" ] ]
0706.0976
Gabriele Travaglini
Adele Nasti, Gabriele Travaglini
One-loop N=8 Supergravity Amplitudes from MHV Diagrams
33 pages, 10 figures
Class.Quant.Grav.24:6071-6096,2007
10.1088/0264-9381/24/23/024
QMUL-PH-07-10
hep-th
null
We discuss the calculation of one-loop amplitudes in N=8 supergravity using MHV diagrams. In contrast to MHV amplitudes of gluons in Yang-Mills, tree-level MHV amplitudes of gravitons are not holomorphic in the spinor variables. In order to extend these amplitudes off shell, and use them as vertices to build loops, we introduce certain shifts for the spinor variables associated to the loop momenta. Using this off-shell prescription, we rederive the four-point MHV amplitude of gravitons at one loop, in complete agreement with known results. We also discuss the extension to the case of one-loop MHV amplitudes with an arbitrary number of gravitons.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:40:01 GMT" } ]
2008-11-26T00:00:00
[ [ "Nasti", "Adele", "" ], [ "Travaglini", "Gabriele", "" ] ]
0706.0977
Sven Heinemeyer
J. Ellis, S. Heinemeyer, K.A. Olive, G. Weiglein
Light Heavy MSSM Higgs Bosons at Large tan_beta
14 pages, 2 figures
Phys.Lett.B653:292-299,2007
10.1016/j.physletb.2007.07.056
CERN-PH-TH/2007-088, DCPT/07/52, IPPP/07/26, UMN-TH-2607/07, FTPI-MINN-07/20
hep-ph
null
The region of MSSM Higgs parameter space currently excluded by the CDF Collaboration, based on an analysis of ~1 fb^-1 of integrated luminosity, is less than the expected sensitivity. We analyze the potential implications of the persistence of this discrepancy within the MSSM, assuming that the soft supersymmetry-breaking contributions to scalar masses are universal, apart from those to the Higgs masses (the NUHM model). We find that a light heavy MSSM Higgs signal in the unexcluded part of the sensitive region could indeed be accommodated in this simple model, even after taking into account other constraints from cold dark matter, electroweak precision observables and B physics observables. In this case the NUHM suggests that supersymmetric signatures should also be detectable in the near future in some other measurements such as BR(B_s -> mu+ mu-), BR(b -> s gamma) and (g-2)_mu, and M_h would have to be very close to the LEP exclusion limit. In addition, the dark matter candidate associated with this model should be on the verge of detection in direct detection experiments.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 09:52:06 GMT" } ]
2008-11-26T00:00:00
[ [ "Ellis", "J.", "" ], [ "Heinemeyer", "S.", "" ], [ "Olive", "K. A.", "" ], [ "Weiglein", "G.", "" ] ]
0706.0978
Jeremy Dunning-Davies
D. Sands and J. Dunning-Davies
The Canonical Ensemble and the Central Limit Theorem
15 pages, 7 figures
null
null
null
physics.gen-ph
null
Some of the more powerful results of mathematical statistics are becoming of increasing importance in statistical mechanics. Here the use of the central limit theorem in conjunction with the canonical ensemble is shown to lead to an interesting and important new insight into results associated with the canonical ensemble. This theoretical work is illustrated numerically and it is shown how this numerical work can form the basis of an undergraduate laboratory experiment which should help to implant ideas of statistical mechanics in students' minds.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:57:25 GMT" } ]
2007-06-08T00:00:00
[ [ "Sands", "D.", "" ], [ "Dunning-Davies", "J.", "" ] ]
0706.0979
Olaf Lechtenfeld
Olaf Lechtenfeld, Alexander D. Popov, Richard J. Szabo
Quiver Gauge Theory and Noncommutative Vortices
talk by O.L. at the 21st Nishinomiya-Yukawa Memorial Symposium, Kyoto, 15 Nov. 2006
Prog.Theor.Phys.Suppl.171:258-268,2007
10.1143/PTPS.171.258
null
hep-th
null
We construct explicit BPS and non-BPS solutions of the Yang-Mills equations on noncommutative spaces R^{2n}_theta x G/H which are manifestly G-symmetric. Given a G-representation, by twisting with a particular bundle over G/H, we obtain a G-equivariant U(k) bundle with a G-equivariant connection over R^{2n}_theta x G/H. The U(k) Donaldson-Uhlenbeck-Yau equations on these spaces reduce to vortex-type equations in a particular quiver gauge theory on R^{2n}_theta. Seiberg-Witten monopole equations are particular examples. The noncommutative BPS configurations are formulated with partial isometries, which are obtained from an equivariant Atiyah-Bott-Shapiro construction. They can be interpreted as D0-branes inside a space-filling brane-antibrane system.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 10:27:36 GMT" } ]
2008-11-26T00:00:00
[ [ "Lechtenfeld", "Olaf", "" ], [ "Popov", "Alexander D.", "" ], [ "Szabo", "Richard J.", "" ] ]
0706.0980
Pascal Vaudrevange
Pascal M. Vaudrevange, Lev Kofman
Trans-Planckian Issue in the Milne Universe
8 pages, 2 figures
null
null
null
hep-th astro-ph gr-qc hep-ph
null
The ``trans-Planckian'' challenge in cosmology appears when we trace the present physical wavelengths of fluctuations backwards in time. They become smaller and smaller until crossing the Planck scale where conventional QFT is challenged, so that unknown ultraviolet physics may be traced in the observable cosmological fluctuations. Usually this issue is addressed in the inflationary context, but trans-Planckian reasoning is much broader. We examine this logic in a simple example of scalar quantum field theory in the expanding and contracting Milne universes, where wavelengths of the eigenmodes are red- or blue-shifted. Trans-Planckian modifications of QFT should result in a UV-dependent VeV of the energy momentum tensor of a scalar field in the Milne universe. On the other hand, the Milne universe is another coordinate systems of flat Minkowski space-time, and the covariant energy momentum tensor should be the same (but vacuum-dependent) in different coordinates of flat space time. We explicitly demonstrate that in conventional QFT the energy momentum tensor, choosing the adiabatic vacuum, is identical to zero in Minkowski coordinates, and remains zero in the contracting Milne universe (due to non-trivial cancellations of contributions from particles which appear in the accelerating frame and from vacuum polarization there). In contrast to this, the trans-Planckian modification of the energy momentum tensor is not motivated. We provide a similar argument for the expanding Milne universe, where the energy momentum tensor in the conformal vacuum is non-zero. Similar arguments are applicable for other cosmological models where the curvature is much lower than Planckian which leads to conflicts with trans-Planckian considerations.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 17:57:50 GMT" } ]
2007-06-08T00:00:00
[ [ "Vaudrevange", "Pascal M.", "" ], [ "Kofman", "Lev", "" ] ]
0706.0981
Yun-Song Piao
Yun-Song Piao
Primordial Perturbations During a Slow Expansion
5 pages, 1 eps figure, minor changes and refs. added, to publish in PRD
Phys.Rev.D76:083505,2007
10.1103/PhysRevD.76.083505
null
gr-qc
null
Recently, it has been showed that a slow expansion, which is asymptotically a static state in infinite past and may be described as an evolution with \epsilon \ll -1, of early universe may lead to the generation of primordial perturbation responsible for the structure formation of observable universe. However, its feasibility depends on whether the growing mode of Bardeen potential before phase transition can be inherited by the constant mode of curvature perturbation after phase transition. In this note, we phenomenally regard this slow expansion as that driven by multi NEC violating scalar fields. We calculate the curvature perturbation induced by the entropy perturbation before phase transition, and find that the spectrum is naturally scale invariant with a slight red tilt. The result has an interesting similarity to that of slow roll inflation.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 10:45:51 GMT" }, { "version": "v2", "created": "Mon, 20 Aug 2007 12:18:17 GMT" } ]
2008-11-26T00:00:00
[ [ "Piao", "Yun-Song", "" ] ]
0706.0982
Dr. Dhananjai Pandey
Satendra Pal Singh, Akhilesh Kumar Singh, Dhananjai Pandey and S. M. Yusuf
Dielectric Relaxation and Phase Transition at Cryogenic Temperatures in 0.65[Pb(Ni_1/3Nb_2/3)O_3]-0.35PbTiO_3 Ceramics
32 pages, 11 figures, To appear in Phys. Rev. B
null
null
null
cond-mat.mtrl-sci
null
Dielectric measurements on 0.65[Pb(Ni_1/3Nb_2/3)O_3]-0.35PbTiO_3 ceramic in the temperature range 90K to 470K shows a relaxor ferroelectric transition around 350K with a Vogel-Fulcher freezing temperature of 338K and appearance of a non-ergodic relaxor ferroelectric phase of tetragonal structure at room temperature. This non-ergodic phase reenters into the relaxor state at low temperatures as evidenced by the appearance of a frequency dependent anomaly in the imaginary part of the dielectric constant around 160K, similar to those reported in other relaxor ferroelectric based morphotropic phase boundary ceramics. The polarization relaxation time for the 160K anomaly also follows Vogel-Fulcher type temperature dependence. Temperature dependent magnetization measurements show that this low temperature anomaly is not linked with any magnetic transition. Elastic modulus and low temperature x-ray diffraction (XRD) measurements reveal a tetragonal to monoclinic phase transition around 225K. It is argued that the low temperature dielectric dispersion around 160K results from the freezing of mesoscopic conformally miniaturized monoclinic domains formed inside the parent tetragonal domains below the structural phase transition temperature of 225K.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 10:42:07 GMT" } ]
2007-06-08T00:00:00
[ [ "Singh", "Satendra Pal", "" ], [ "Singh", "Akhilesh Kumar", "" ], [ "Pandey", "Dhananjai", "" ], [ "Yusuf", "S. M.", "" ] ]
0706.0983
S. Q. Wu
Shuang-Qing Wu and Jun-Jin Peng
Anomalies and Hawking radiation from the Reissner-Nordstr\"om black hole with a global monopole
18 pages, 0 figure. 1 footnote and 4 new reference added
Class.Quant.Grav.24:5123-5138,2007
10.1088/0264-9381/24/20/013
null
hep-th gr-qc
null
We extend the work by S. Iso, H. Umetsu and F. Wilczek [Phys. Rev. Lett. 96 (2006) 151302] to derive the Hawking flux via gauge and gravitational anomalies of a most general two-dimensional non-extremal black hole space-time with the determinant of its diagonal metric differing from the unity ($\sqrt{-g} \neq 1$) and use it to investigate Hawking radiation from the Reissner-Nordstrom black hole with a global monopole by requiring the cancellation of anomalies at the horizon. It is shown that the compensating energy momentum and gauge fluxes required to cancel gravitational and gauge anomalies at the horizon are precisely equivalent to the $(1+1)$-dimensional thermal fluxes associated with Hawking radiation emanating from the horizon at the Hawking temperature. These fluxes are universally determined by the value of anomalies at the horizon.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 11:04:28 GMT" }, { "version": "v2", "created": "Fri, 8 Jun 2007 14:52:48 GMT" }, { "version": "v3", "created": "Mon, 11 Jun 2007 01:23:20 GMT" }, { "version": "v4", "created": "Wed, 13 Jun 2007 08:22:31 GMT" }, { "version": "v5", "created": "Thu, 16 Aug 2007 04:14:25 GMT" } ]
2008-11-26T00:00:00
[ [ "Wu", "Shuang-Qing", "" ], [ "Peng", "Jun-Jin", "" ] ]
0706.0984
Michael C. Birse
Michael C. Birse (Manchester)
Deconstructing triplet nucleon-nucleon scattering
13 pages, RevTeX, 8 figures, minor clarifications added
Phys.Rev.C76:034002,2007
10.1103/PhysRevC.76.034002
null
nucl-th hep-ph
null
Nucleon-nucleon scattering in spin-triplet channels is analysed within an effective field theory where one-pion exchange is treated nonperturbatively. Justifying this requires the identification of an additional low-energy scale in the strength of that potential. Short-range interactions are organised according to the resulting power counting, in which the leading term is promoted to significantly lower order than in the usual perturbative counting. In each channel there is a critical momentum above which the waves probe the singular core of the tensor potential and the new counting is necessary. When the effects of one- and two-pion exchange have been removed using a distorted-wave Born approximation, the residual scattering in waves with L<=2 is well described by the first three terms in the new counting. In contrast, the scattering in waves with L>=3 is consistent with the perturbative counting, at least for energies up to 300 MeV. This pattern is in agreement with estimates of the critical momenta in these channels.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 11:03:49 GMT" }, { "version": "v2", "created": "Tue, 14 Aug 2007 11:28:14 GMT" } ]
2008-11-26T00:00:00
[ [ "Birse", "Michael C.", "", "Manchester" ] ]
0706.0985
Etera R. Livine
Etera R. Livine, Daniel R. Terno
Bulk Entropy in Loop Quantum Gravity
13 pages
Nucl.Phys.B794:138-153,2008
10.1016/j.nuclphysb.2007.10.027
null
gr-qc
null
In the framework of loop quantum gravity (LQG), having quantum black holes in mind, we generalize the previous boundary state counting (gr-qc/0508085) to a full bulk state counting. After a suitable gauge fixing we are able to compute the bulk entropy of a bounded region (the "black hole") with fixed boundary. This allows us to study the relationship between the entropy and the boundary area in details and we identify a holographic regime of LQG where the leading order of the entropy scales with the area. We show that in this regime we can fine tune the factor between entropy and area without changing the Immirzi parameter.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 11:35:14 GMT" } ]
2008-11-26T00:00:00
[ [ "Livine", "Etera R.", "" ], [ "Terno", "Daniel R.", "" ] ]
0706.0986
Fuminobu Takahashi
Motoi Endo, Fuminobu Takahashi, T. T. Yanagida
Inflaton Decay in Supergravity
41 pages, 5 figures. v2: references and supplementary sections added, a version to appear in Phys. Rev. D
Phys.Rev.D76:083509,2007
10.1103/PhysRevD.76.083509
DESY 07-061
hep-ph astro-ph hep-th
null
We discuss inflaton decay in supergravity, taking account of the gravitational effects. It is shown that, if the inflaton has a nonzero vacuum expectation value, it generically couples to any matter fields that appear in the superpotential at the tree level, and to any gauge sectors through anomalies in the supergravity. Through these processes, the inflaton generically decays into the supersymmetry breaking sector, producing many gravitinos. The inflaton also directly decays into a pair of the gravitinos. We derive constraints on both inflation models and supersymmetry breaking scenarios for avoiding overproduction of the gravitinos. Furthermore, the inflaton naturally decays into the visible sector via the top Yukawa coupling and SU(3)_C gauge interactions.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 11:40:12 GMT" }, { "version": "v2", "created": "Fri, 17 Aug 2007 09:31:44 GMT" } ]
2008-11-26T00:00:00
[ [ "Endo", "Motoi", "" ], [ "Takahashi", "Fuminobu", "" ], [ "Yanagida", "T. T.", "" ] ]
0706.0987
Danny Steeghs
D.Steeghs (CfA/Warwick), S.Howell (NOAO), C.Knigge (Southampton), B.Gaensicke (Warwick), E.Sion (Villanova), W.Welsh (SDSU)
Dynamical constraints on the component masses of the cataclysmic variable WZ Sge
6 pages, 3 figures, accepted for publication in the Astrophysical Journal
null
10.1086/520702
null
astro-ph
null
We present phase-resolved spectroscopy of the short period cataclysmic variable WZ Sge obtained with the Hubble Space Telescope. We were able to resolve the orbital motion of a number of absorption lines that likely probe the environment near the accreting white dwarf. The radial velocities derived from simultaneous fits to 13 absorption lines indicate an orbital velocity semi-amplitude of K_UV = 47 +/- 3 km/s. However, we find that the phase zero is offset from the white dwarf ephemeris by +0.1. Our offset and velocity amplitude are very similar to constraints derived from optical emission lines from the quiescent accretion disk, despite the fact that we are probing material much closer to the primary. If we associate the UV amplitude with K_1, our dynamical constraints together with the K_2 estimates from Steeghs et al. (2001) and the known binary inclination of i=77+/-2 imply 0.88<M_1<1.53 M_sun, 0.078 < M_2 < 0.13 M_sun and 0.075<q=M_2/M_1<0.101. If we interpret the mean velocity of the UV lines (-16+/-4 km/s) as being due to the gravitational red-shift caused in the high-g environment near the white dwarf, we find v_grav=56+/-5 km/s which provides an independent estimate on the mass of the primary of M_1=0.85+/-0.04 M_sun when coupled with a mass-radius relation. Our primary mass estimates are in excellent agreement and are also self-consistent with spectrophotometric fits to the UV fluxes despite the observed phase offset. It is at this point unclear what causes the observed phase-offset in the UV spectra and by how much it distorts the radial velocity signature from the underlying white dwarf.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 11:40:26 GMT" } ]
2009-11-13T00:00:00
[ [ "Steeghs", "D.", "", "CfA/Warwick" ], [ "Howell", "S.", "", "NOAO" ], [ "Knigge", "C.", "", "Southampton" ], [ "Gaensicke", "B.", "", "Warwick" ], [ "Sion", "E.", "", "Villanova" ], [ "Welsh", "W.", "", "SDSU" ] ]
0706.0988
Lothar G\"ottsche
Barbara Fantechi and Lothar G\"ottsche
Riemann-Roch theorems and elliptic genus for virtually smooth Schemes
31 pages
Geom. Topol. 14 (2010) 83-115
10.2140/gt.2010.14.83
null
math.AG
null
For a proper scheme X with a fixed 1-perfect obstruction theory, we define virtual versions of holomorphic Euler characteristic, chi y-genus, and elliptic genus; they are deformation invariant, and extend the usual definition in the smooth case. We prove virtual versions of the Grothendieck-Riemann-Roch and Hirzebruch-Riemann-Roch theorems. We show that the virtual chi y-genus is a polynomial, and use this to define a virtual topological Euler characteristic. We prove that the virtual elliptic genus satisfies a Jacobi modularity property; we state and prove a localization theorem in the toric equivariant case. We show how some of our results apply to moduli spaces of stable sheaves.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 11:59:12 GMT" } ]
2014-11-11T00:00:00
[ [ "Fantechi", "Barbara", "" ], [ "Göttsche", "Lothar", "" ] ]
0706.0989
Luis Anchordoqui
Luis Anchordoqui (for the Pierre Auger Collaboration)
Search for Coincidences in Time and Arrival Direction of Auger Data with Astrophysical Transients
To be published in Proceedings of the 30th International Cosmic Ray Conference, July 3 - 11, 2007, Merida, Yucatan, Mexico
null
null
null
astro-ph
null
The data collected by the Pierre Auger Observatory are analyzed to search for coincidences between the arrival directions of high-energy cosmic rays and the positions in the sky of astrophysical transients. Special attention is directed towards gamma ray observations recorded by NASA's Swift mission, which have an angular resolution similar to that of the Auger surface detectors. In particular, we check our data for evidence of a signal associated with the giant flare that came from the soft gamma repeater 1806-20 on December 27, 2004.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 11:49:46 GMT" } ]
2019-08-13T00:00:00
[ [ "Anchordoqui", "Luis", "", "for the Pierre Auger Collaboration" ] ]
0706.0990
Claude Bervillier
C. Bervillier, B. Boisseau, H. Giacomini
Analytical approximation schemes for solving exact renormalization group equations in the local potential approximation
Final version to appear in Nucl. Phys. B. Some references added correctly
Nucl.Phys.B789:525-551,2008
10.1016/j.nuclphysb.2007.07.005
null
hep-th
null
The relation between the Wilson-Polchinski and the Litim optimized ERGEs in the local potential approximation is studied with high accuracy using two different analytical approaches based on a field expansion: a recently proposed genuine analytical approximation scheme to two-point boundary value problems of ordinary differential equations, and a new one based on approximating the solution by generalized hypergeometric functions. A comparison with the numerical results obtained with the shooting method is made. A similar accuracy is reached in each case. Both two methods appear to be more efficient than the usual field expansions frequently used in the current studies of ERGEs (in particular for the Wilson-Polchinski case in the study of which they fail).
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:09:07 GMT" }, { "version": "v2", "created": "Thu, 11 Oct 2007 09:07:34 GMT" } ]
2008-11-26T00:00:00
[ [ "Bervillier", "C.", "" ], [ "Boisseau", "B.", "" ], [ "Giacomini", "H.", "" ] ]
0706.0991
Adamantios Stavridis
Andrea Passamonti, Adamantios Stavridis, Kostas Kokkotas
Non-axisymmetric oscillations of differentially rotating relativistic stars
17 pages, 7 figures, 8 tables, version accepted for publication to Phys. Rev. D
Phys.Rev.D77:024029,2008
10.1103/PhysRevD.77.024029
null
gr-qc astro-ph
null
Non-axisymmetric oscillations of differentially rotating stars are studied using both slow rotation and Cowling approximation. The equilibrium stellar models are relativistic polytropes where differential rotation is described by the relativistic j-constant rotation law. The oscillation spectrum is studied versus three main parameters: the stellar compactness $M/R$, the degree of differential rotation $A$ and the number of maximun couplings $\ell_{\rm max}$. It is shown that the rotational splitting of the non-axisymmetric modes is strongly enhached by increasing the compactness of the star and the degree of differential rotation. Finally, we investigate the relation between the fundamental quadrupole mode and the corotation band of differentially rotating stars.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:11:41 GMT" }, { "version": "v2", "created": "Wed, 5 Dec 2007 09:25:42 GMT" } ]
2008-11-26T00:00:00
[ [ "Passamonti", "Andrea", "" ], [ "Stavridis", "Adamantios", "" ], [ "Kokkotas", "Kostas", "" ] ]
0706.0992
Eugen Radu
Eugen Radu and Mihai Visinescu
A note on Klein-Gordon equation in a generalized Kaluza-Klein monopole background
11 pages, 2 figures; v2: minor corrections, to appear in MPLA
Mod.Phys.Lett.A22:1621-1634,2007
10.1142/S0217732307024127
null
gr-qc
null
We investigate solutions of the Klein-Gordon equation in a class of five dimensional geometries presenting the same symmetries and asymptotic structure as the Gross-Perry-Sorkin monopole solution. Apart from globally regular metrics, we consider also squashed Kaluza-Klein black holes backgrounds.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:23:45 GMT" }, { "version": "v2", "created": "Thu, 21 Jun 2007 15:00:59 GMT" } ]
2008-11-26T00:00:00
[ [ "Radu", "Eugen", "" ], [ "Visinescu", "Mihai", "" ] ]
0706.0993
Donald M. Davis
Martin Bendersky and Donald M. Davis
v1-periodic homotopy groups of the Dwyer-Wilkerson space
16 pages
null
null
null
math.AT
null
The Dwyer-Wilkerson space DI(4) is the only exotic 2-compact group. We compute its v1-periodic homotopy groups.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:28:04 GMT" } ]
2007-06-08T00:00:00
[ [ "Bendersky", "Martin", "" ], [ "Davis", "Donald M.", "" ] ]
0706.0994
Vladimir Babichenko
V. S. Babichenko
Correlation Properties of the Electron-Hole Plasma Interecting with the Exciton Gas and the Formation of Inhomogeneous State
9 pages
null
null
null
cond-mat.str-el
null
The correlation properties of the cold system consisting of the electron-hole plasma interacting with the exciton gas are analyzed. It is shown that the homogeneous state of the system is unstable and in the stationary state the densities of the electron-hole plasma and exciton gas are modulated.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:29:53 GMT" }, { "version": "v2", "created": "Fri, 21 Sep 2007 09:46:42 GMT" } ]
2011-11-10T00:00:00
[ [ "Babichenko", "V. S.", "" ] ]
0706.0995
Alejandro Gangui
Diego Hurtado de Mendoza
Between Pacifism and Nuclear Energy (1930-1955)
9 pages, Published in Spanish in "El universo de Einstein: 1905 - annus mirabilis - 2005", Alejandro Gangui (ed.), Editorial EUDEBA, 2007 (arXiv:0705.4266). Also available at http://www.universoeinstein.com.ar/
null
null
UEinstein/2007/09
physics.hist-ph physics.pop-ph
null
The atomic bomb American program known as Manhattan Project has been studied in detail. Historians argue that the beginning of this program is rooted in the letter Einstein sent to American President Roosevelt in the summer of 1939. This article examines Einstein's activities before 1933 as radical pacifist in favor of the principles of universal disarmament and outspoken supporter of individual war resistance and the shift of this posture when Hitler came to power in 1933. In this context, we discuss the role played by nuclear physicists during the Second World War and Einstein's decision to promote the construction of an atomic weapon in the United States. Finally, the article analyzes Einstein's struggle against the atomic race during the beginning of the cold war.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:29:55 GMT" } ]
2007-06-08T00:00:00
[ [ "de Mendoza", "Diego Hurtado", "" ] ]
0706.0996
Hsi-Sheng Goan
Kuan-Liang Liu and Hsi-Sheng Goan
Non-Markovian entanglement dynamics of quantum continuous variable systems in thermal environments
10 two-column pages, 8 figures, to appear in Phys. Rev. A
Phys. Rev. A 76, 022312 (2007) (12 pages)
10.1103/PhysRevA.76.022312
null
quant-ph cond-mat.mes-hall
null
We study two continuous variable systems (or two harmonic oscillators) and investigate their entanglement evolution under the influence of non-Markovian thermal environments. The continuous variable systems could be two modes of electromagnetic fields or two nanomechanical oscillators in the quantum domain. We use quantum open system method to derive the non-Markovian master equations of the reduced density matrix for two different but related models of the continuous variable systems. The two models both consist of two interacting harmonic oscillators. In model A, each of the two oscillators is coupled to its own independent thermal reservoir, while in model B the two oscillators are coupled to a common reservoir. To quantify the degrees of entanglement for the bipartite continuous variable systems in Gaussian states, logarithmic negativity is used. We find that the dynamics of the quantum entanglement is sensitive to the initial states, the oscillator-oscillator interaction, the oscillator-environment interaction and the coupling to a common bath or to different, independent baths.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:46:45 GMT" } ]
2009-11-13T00:00:00
[ [ "Liu", "Kuan-Liang", "" ], [ "Goan", "Hsi-Sheng", "" ] ]
0706.0997
Oksana Manyuhina
O.V. Manyuhina, A. Fasolino, M.I. Katsnelson
Slow dynamics in a model of the cellulose network
13 pages, 7 figures, accepted in Polymer
Polymer 48, 4849 (2007)
null
null
cond-mat.dis-nn cond-mat.soft
null
We present numerical simulations of a model of cellulose consisting of long stiff rods, representing cellulose microfibrils, connected by stretchable crosslinks, representing xyloglucan molecules, hydrogen bonded to the microfibrils. Within a broad range of temperature the competing interactions in the resulting network give rise to a slow glassy dynamics. In particular, the structural relaxation described by orientational correlation functions shows a logarithmic time dependence. The glassy dynamics is found to be due to the frustration introduced by the network of xyloglucan molecules. Weakening of interactions between rod and xyloglucan molecules results in a more marked reorientation of cellulose microfibrils, suggesting a possible mechanism to modify the dynamics of the plant cell wall.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:39:17 GMT" } ]
2009-07-10T00:00:00
[ [ "Manyuhina", "O. V.", "" ], [ "Fasolino", "A.", "" ], [ "Katsnelson", "M. I.", "" ] ]
0706.0998
Maria Giuseppina Adesso
M. G. Adesso, R. Flukiger, T. Giamarchi, W. Goldacker, H. Kupfer, S. Pace, M. Polichetti, D. Uglietti
New aspects in the Bragg Glass-Disordered phase transition: an analysis based on the 3rd harmonics of the AC magnetic susceptibility
10 pages, 5 figures
null
null
null
cond-mat.supr-con
null
We analyse the phase transition between the Bragg Glass and the Disordered phase in the vortex lattice in type-II superconductors, both by analytical computations and experimental investigations. It is known that if the Peak Effect can be detected, a Bragg Glass/Disordered phase transition takes place. We show that, in some conditions, this transition can occur without the observation of the Peak Effect Phenomenon. We introduce a method based on the 3rd harmonics of the AC magnetic susceptibility to detect the transition also in these cases. Using this method, we obtain an experimental confirmation of the theoretical predictions on sphere shaped V3Si single crystals, in the high fields/low temperatures range too, where previous experimental studies failed to detect the Bragg/Disordered phase transition.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:43:44 GMT" } ]
2007-06-08T00:00:00
[ [ "Adesso", "M. G.", "" ], [ "Flukiger", "R.", "" ], [ "Giamarchi", "T.", "" ], [ "Goldacker", "W.", "" ], [ "Kupfer", "H.", "" ], [ "Pace", "S.", "" ], [ "Polichetti", "M.", "" ], [ "Uglietti", "D.", "" ] ]
0706.0999
Alejandro Gangui
Daniel Salom\'on
Einstein in the crossroad of the sciences, arts and humanities
15 pages, Published in Spanish in "El universo de Einstein: 1905 - annus mirabilis - 2005", Alejandro Gangui (ed.), Editorial EUDEBA, 2007 (arXiv:0705.4266). Also available at http://www.universoeinstein.com.ar/
null
null
UEinstein/2007/24
physics.hist-ph physics.pop-ph
null
Western thinking underwent a turning point between 1885 and 1925. Einstein in 1905 symbolizes the emblematic hinge of this change of direction. To find an equivalent phenomenon in the past we need to go back to the period from the XV century to the XVII century. It was not a mere reform of codes but a new code. In 1905 the perception of reality changed through the introduction of relativism in three levels of the reference systems: the ego-other relation, the world perceived by the senses, and the 'ideal' universe of the concepts. We will try to identify how this change was expressed and developed in the cited levels, both in the physic and nature based sciences, in the social sciences, and in literature and fine arts. Today, 100 years after, the 1905's generation still proposes us two options: to live sheltered by the dogma that reassures us with its only and exclusive viewpoint claimed objective, or to dare to live with the multiple, the transient, the relative. The first way led to the worst regimes and intolerant ideas of the XX century, the second option throws us into the uncertainty of the creative adventure, but also leads us to the possibility of a fairer society in the XXI century.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 13:32:17 GMT" } ]
2007-06-08T00:00:00
[ [ "Salomón", "Daniel", "" ] ]
0706.1000
Dario Alf\`e
D. Alfe` and M. J. Gillan (University College London)
Ab initio statistical mechanics of surface adsorption and desorption: I. H$_2$O on MgO (001) at low coverage
11 pages + 10 figures
null
10.1063/1.2772258
null
cond-mat.stat-mech cond-mat.mtrl-sci
null
We present a general computational scheme based on molecular dynamics (m.d.) simulation for calculating the chemical potential of adsorbed molecules in thermal equilibrium on the surface of a material. The scheme is based on the calculation of the mean force in m.d. simulations in which the height of a chosen molecule above the surface is constrained, and subsequent integration of the mean force to obtain the potential of mean force and hence the chemical potential. The scheme is valid at any coverage and temperature, so that in principle it allows the calculation of the chemical potential as a function of coverage and temperature. It avoids all statistical mechanical approximations, except for the use of classical statistical mechanics for the nuclei, and assumes nothing in advance about the adsorption sites. From the chemical potential, the absolute desorption rate of the molecules can be computed, provided the equilibration rate on the surface is faster than the desorption rate. We apply the theory by {\em ab initio} m.d. simulation to the case of H$_2$O on MgO (001) in the low-coverage limit, using the Perdew-Burke-Ernzerhof (PBE) form of exchange-correlation. The calculations yield an {\em ab initio} value of the Polanyi-Wigner frequency prefactor, which is more than two orders of magnitude greater than the value of $10^{13}$ s$^{-1}$ often assumed in the past. Provisional comparison with experiment suggests that the PBE adsorption energy may be too low, but the extension of the calculations to higher coverages is needed before firm conclusions can be drawn. The possibility of including quantum nuclear effects by using path-integral simulations is noted.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:53:10 GMT" } ]
2009-11-13T00:00:00
[ [ "Alfe`", "D.", "", "University College London" ], [ "Gillan", "M. J.", "", "University College London" ] ]
0706.1001
Krzysztof R. Apt
Krzysztof R. Apt
Epistemic Analysis of Strategic Games with Arbitrary Strategy Sets
8 pages Proc. of the 11th Conference on Theoretical Aspects of Rationality and Knowledge (TARK XI), 2007. To appear
null
null
null
cs.GT cs.AI
null
We provide here an epistemic analysis of arbitrary strategic games based on the possibility correspondences. Such an analysis calls for the use of transfinite iterations of the corresponding operators. Our approach is based on Tarski's Fixpoint Theorem and applies both to the notions of rationalizability and the iterated elimination of strictly dominated strategies.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 12:57:21 GMT" } ]
2007-06-08T00:00:00
[ [ "Apt", "Krzysztof R.", "" ] ]
0706.1002
Alexander Wolff
Xavier Goaoc, Jan Kratochvil, Yoshio Okamoto, Chan-Su Shin, Alexander Wolff
Moving Vertices to Make Drawings Plane
This paper has been merged with http://arxiv.org/abs/0709.0170
null
null
null
cs.CG cs.CC cs.DM
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A straight-line drawing $\delta$ of a planar graph $G$ need not be plane, but can be made so by moving some of the vertices. Let shift$(G,\delta)$ denote the minimum number of vertices that need to be moved to turn $\delta$ into a plane drawing of $G$. We show that shift$(G,\delta)$ is NP-hard to compute and to approximate, and we give explicit bounds on shift$(G,\delta)$ when $G$ is a tree or a general planar graph. Our hardness results extend to 1BendPointSetEmbeddability, a well-known graph-drawing problem.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 13:57:52 GMT" }, { "version": "v2", "created": "Wed, 28 Nov 2007 13:14:51 GMT" }, { "version": "v3", "created": "Thu, 6 Nov 2008 21:57:09 GMT" } ]
2008-11-06T00:00:00
[ [ "Goaoc", "Xavier", "" ], [ "Kratochvil", "Jan", "" ], [ "Okamoto", "Yoshio", "" ], [ "Shin", "Chan-Su", "" ], [ "Wolff", "Alexander", "" ] ]
0706.1003
Serge Tabachnikov
Serge Tabachnikov
A proof of Culter's theorem on the existence of periodic orbits in polygonal outer billiards
null
null
null
null
math.DS
null
We discuss a recent result by C. Culter: every polygonal outer billiard has a periodic trajectory.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 13:32:19 GMT" } ]
2007-06-08T00:00:00
[ [ "Tabachnikov", "Serge", "" ] ]
0706.1004
Detlef Mueller
Isroil A.Ikromov and Detlef M\"uller
On adapted coordinate systems
31 pages, 6 figures
null
null
null
math.CA
null
The notion of an adapted coordinate system, introduced by V.I.Arnol'd, plays an important role in the study of asymptotic expansions of oscillatory integrals. In two dimensions, A.N.Varchenko gave sufficient conditions for the adaptness of a given coordinate system and proved the existence of an adapted coordinate system for a class of analytic functions without multiple components. Varchenko's proof is based on Hironaka's theorem on the resolution of singularities. In this article, we present a new, elementary and concrete approach to these results, which is based on the Puiseux series expansion of roots of the given function. Our method applies to arbitrary real analytic functions, and even extends to arbitrary smooth functions of finite type. Moreover, by avoiding Hironaka's theorem, we can give necessary and sufficient conditions for the adaptedness of a given coordinate system in the smooth, finite type setting.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 13:38:40 GMT" } ]
2007-06-08T00:00:00
[ [ "Ikromov", "Isroil A.", "" ], [ "Müller", "Detlef", "" ] ]
0706.1005
Dan Stamper-Kurn
Kater W. Murch, Kevin L. Moore, Subhadeep Gupta, and Dan M. Stamper-Kurn
Observation of quantum-measurement backaction with an ultracold atomic gas
Article and supplementary information. Version submitted to Nature Physics
null
null
null
quant-ph
null
Current research on micro-mechanical resonators strives for quantum-limited detection of the motion of macroscopic objects. Prerequisite to this goal is the observation of measurement backaction consistent with quantum metrology limits. However, thermal noise presently dominates measurements and precludes ground-state preparation of the resonator. Here we establish the collective motion of an ultracold atomic gas confined tightly within a Fabry-Perot optical cavity as a system for investigating the quantum mechanics of macroscopic bodies. The cavity-mode structure selects a single collective vibrational mode that is measured by the cavity's optical properties, actuated by the cavity optical field, and subject to backaction by the quantum force fluctuations of this field. Experimentally, we quantify such fluctuations by measuring the cavity-light-induced heating of the intracavity atomic ensemble. These measurements represent the first observation of backaction on a macroscopic mechanical resonator at the standard quantum limit.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 19:14:07 GMT" }, { "version": "v2", "created": "Fri, 31 Aug 2007 14:59:56 GMT" }, { "version": "v3", "created": "Tue, 22 Apr 2008 23:11:12 GMT" } ]
2008-04-23T00:00:00
[ [ "Murch", "Kater W.", "" ], [ "Moore", "Kevin L.", "" ], [ "Gupta", "Subhadeep", "" ], [ "Stamper-Kurn", "Dan M.", "" ] ]
0706.1006
Detlef Mueller
Isroil A.Ikromov, Michael Kempe and Detlef M\"uller
Sharp $L^p$-estimates for maximal operators associated to hypersurfaces in $\bR^3$ for $p>2.$
104 pages, 2 figures
null
null
null
math.CA
null
We study the boundedness problem for maximal operators $\M$ associated to smooth hypersurfaces $S$ in 3-dimensional Euclidean space. For $p>2,$ we prove that if no affine tangent plane to $S$ passes through the origin and $S$ is analytic, then the associated maximal operator is bounded on $L^p(\RR^3)$ if and only if $p>h(S),$ where $h(S)$ denotes the so-called height of the surface $S.$ For non-analytic finite type $S$ we obtain the same statement with the exception of the exponent $p=h(S).$ Our notion of height $h(S)$ is closely related to A. N. Varchenko's notion of height $h(\phi)$ for functions $\phi$ such that $S$ can be locally represented as the graph of $\phi$ after a rotation of coordinates. Several consequences of this result are discussed. In particular we verify a conjecture by E.M. Stein and its generalization by A. Iosevich and E. Sawyer on the connection between the decay rate of the Fourier transform of the surface measure on $S$ and the $L^p$-boundedness of the associated maximal operator $\M$, and a conjecture by Iosevich and Sawyer which relates the $L^p$-boundedness of $\M$ to an integrability condition on $S$ for the distance function to tangential hyperplanes, in dimension three. In particular, we also give ess. sharp uniform estimates for the Fourier transform of the surface measure on $S,$ thus extending a result by V.N. Karpushkin from the analytic to the smooth setting and implicitly verifying a conjecture by V.I. Arnol'd in our context.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 14:01:41 GMT" } ]
2007-06-08T00:00:00
[ [ "Ikromov", "Isroil A.", "" ], [ "Kempe", "Michael", "" ], [ "Müller", "Detlef", "" ] ]
0706.1007
Rafael Zulkarneev
R.Ya.Zulkarneev
Does the fireball found in AuAu collisions at RHIC resemble plasma?
7 pages, 2 tables
null
null
null
nucl-th
null
General properties of the hot and dense hadron matter (fireball) discovered in AuAu collisions with pSNN = 130 and 200 GeV at RHIC are compared with these for ideal electromagnetic plasma. None of them was found to be in contrary to those of the plasma typical signs distinguishing its from other aggregate states of the matter. The author notes that modern experimental data about the fireball properties are limited to make their comprehensive comparison with plasma signatures. The author also points out the directions needed to be studied to answer question whether the hadron matter observed in the RHIC experiments is a color analogue of the electromagnetic plasma or not.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 14:18:19 GMT" } ]
2007-06-08T00:00:00
[ [ "Zulkarneev", "R. Ya.", "" ] ]
0706.1008
M. C. Nucci
M.C. Nucci and P.G.L. Leach
Lagrangians Galore
16 pages
null
10.1063/1.2821612
null
nlin.SI math-ph math.MP physics.class-ph
null
Searching for a Lagrangian may seem either a trivial endeavour or an impossible task. In this paper we show that the Jacobi last multiplier associated with the Lie symmetries admitted by simple models of classical mechanics produces (too?) many Lagrangians in a simple way. We exemplify the method by such a classic as the simple harmonic oscillator, the harmonic oscillator in disguise [H Goldstein, {\it Classical Mechanics}, 2nd edition (Addison-Wesley, Reading, 1980)] and the damped harmonic oscillator. This is the first paper in a series dedicated to this subject.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 14:20:35 GMT" } ]
2009-11-13T00:00:00
[ [ "Nucci", "M. C.", "" ], [ "Leach", "P. G. L.", "" ] ]
0706.1009
Zhou Yue
Lun Lv, Guoce Xin, and Yue Zhou
A Family of $q$-Dyson Style Constant Term Identities
21 pages
null
null
null
math.AC math.CO
null
By generalizing Gessel-Xin's Laurent series method for proving the Zeilberger-Bressoud $q$-Dyson Theorem, we establish a family of $q$-Dyson style constant term identities. These identities give explicit formulas for certain coefficients of the $q$-Dyson product, including three conjectures of Sills' as special cases and generalizing Stembridge's first layer formulas for characters of $SL(n,\mathbb{C})$.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 14:22:56 GMT" } ]
2007-06-08T00:00:00
[ [ "Lv", "Lun", "" ], [ "Xin", "Guoce", "" ], [ "Zhou", "Yue", "" ] ]
0706.1010
Dmitriy Kulikov
D. A. Kulikov, R. S. Tutik
Relativistic wave equation for one spin-1/2 and one spin-0 particle
Talk given at International School-Seminar "New physics and QCD at external conditions" (Dniepropetrovsk, Ukraine, May 3-6, 2007); 8 pages; prepared for publication in Proceedings
null
null
null
hep-th
null
A new approach to the two-body problem based on the extension of the $SL(2,C)$ group to the $Sp(4,C)$ one is developed. The wave equation with the Lorentz-scalar and Lorentz-vector potential interactions for the system of one spin-1/2 and one spin-0 particle with unequal masses is constructed.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 14:35:31 GMT" } ]
2007-06-08T00:00:00
[ [ "Kulikov", "D. A.", "" ], [ "Tutik", "R. S.", "" ] ]
0706.1011
Michele Grassi
Giovanni Gaiffi, Michele Grassi
A natural Lie superalgebra bundle on rank three WSD manifolds
20 pages, 4 tables. Minor changes in presentation from v1
null
null
null
math.DG math.RT
null
We determine the structure of the $*$-Lie superalgebra generated by a set of carefully chosen natural operators of an orientable WSD manifold of rank three. This Lie superalgebra is formed by global sections of a natural Lie superalgebra bundle, and turns out to be a product of $\mathbf{sl}(4,\C)$ with the full special linear superalgebras of some graded vector spaces isotypical with respect to a natural action of $\mathbf{so}(3,\R)$. We provide an explicit description of one of the real forms of this superalgebra, which is geometrically natural being made of $\mathbf{so}(3,\R)$-invariant operators which preserve the Poincar\'e (odd Hermitean) inner product on the bundle of forms.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 14:40:36 GMT" }, { "version": "v2", "created": "Thu, 12 Jul 2007 09:24:40 GMT" } ]
2007-07-12T00:00:00
[ [ "Gaiffi", "Giovanni", "" ], [ "Grassi", "Michele", "" ] ]
0706.1012
Claudio Cazorla
C. Cazorla, M. J. Gillan, S. Taioli and D. Alf\`e
Ab initio melting curve of molybdenum by the phase coexistence method
27 pages, 10 figures. to be published in Journal of Chemical Physics
null
10.1063/1.2735324
null
cond-mat.mtrl-sci cond-mat.str-el
null
We report ab initio calculations of the melting curve of molybdenum for the pressure range 0-400 GPa. The calculations employ density functional theory (DFT) with the Perdew-Burke-Ernzerhof exchange-correlation functional in the projector augmented wave (PAW) implementation. We present tests showing that these techniques accurately reproduce experimental data on low-temperature b.c.c. Mo, and that PAW agrees closely with results from the full-potential linearized augmented plane-wave implementation. The work attempts to overcome the uncertainties inherent in earlier DFT calculations of the melting curve of Mo, by using the ``reference coexistence'' technique to determine the melting curve. In this technique, an empirical reference model (here, the embedded-atom model) is accurately fitted to DFT molecular dynamics data on the liquid and the high-temperature solid, the melting curve of the reference model is determined by simulations of coexisting solid and liquid, and the ab initio melting curve is obtained by applying free-energy corrections. Our calculated melting curve agrees well with experiment at ambient pressure and is consistent with shock data at high pressure, but does not agree with the high pressure melting curve deduced from static compression experiments. Calculated results for the radial distribution function show that the short-range atomic order of the liquid is very similar to that of the high-T solid, with a slight decrease of coordination number on passing from solid to liquid. The electronic densities of states in the two phases show only small differences. The results do not support a recent theory according to which very low dTm/dP values are expected for b.c.c. transition metals because of electron redistribution between s-p and d states.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 14:46:45 GMT" } ]
2009-11-13T00:00:00
[ [ "Cazorla", "C.", "" ], [ "Gillan", "M. J.", "" ], [ "Taioli", "S.", "" ], [ "Alfè", "D.", "" ] ]
0706.1013
Anatoly Voronin
Anatoly V. Voronin and Sergey I. Chernyshov
Cycles in Nonlinear Macroeconomics
100 pages, 16 figures; the figures corrected
null
null
null
nlin.AO
null
The monograph is concerned with some key problems of the theory of nonlinear economic dynamics. The authors' concept consists in analyzing the problem of structural instability of economic systems within the framework of the synergetic paradigm. As examples, the classical models of macroeconomics are considered. The authors present the results of the study of the phenomenon of self-organization in open and nonequilibrium economic systems. The generation of limit cycles, as well as of more complex periodic structures, is discussed; the character of their stability is examined.
[ { "version": "v1", "created": "Thu, 7 Jun 2007 14:47:24 GMT" }, { "version": "v2", "created": "Mon, 11 Jun 2007 11:43:53 GMT" } ]
2007-06-14T00:00:00
[ [ "Voronin", "Anatoly V.", "" ], [ "Chernyshov", "Sergey I.", "" ] ]