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0704.4001
Michael R. Douglas
Michael R. Douglas, Jessie Shelton and Gonzalo Torroba
Warping and Supersymmetry Breaking
Latex, 29 pp, 1 figure. Reference added, some typos corrected and minor changes to the content
null
null
RUNHETC-07-05
hep-th
null
We analyze supersymmetry breaking by anti-self-dual flux in the deformed conifold. This theory has been argued to be a dual realization of susy breaking by antibranes. As such, one might expect it to lead to a hierarchically small breaking scale, but only if the warp factor is taken into account. We verify this by explicitly computing the warp-modified moduli space metric. This leads to a new term, with a power-like divergence at the conifold point, which lowers the breaking scale. We finally point out various puzzles regarding the gauge theory interpretation of these results.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 19:40:40 GMT" }, { "version": "v2", "created": "Mon, 28 Jan 2008 20:48:02 GMT" } ]
2008-01-28T00:00:00
[ [ "Douglas", "Michael R.", "" ], [ "Shelton", "Jessie", "" ], [ "Torroba", "Gonzalo", "" ] ]
0704.4002
Jesper Grodal
Kasper K. S. Andersen and Jesper Grodal
The Steenrod problem of realizing polynomial cohomology rings
14 pages. v3: Final version. To appear in Journal of Topology
J Topology 2008 1: 747-760
10.1112/jtopol/jtn021
null
math.AT math.GR
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we completely classify which graded polynomial R-algebras in finitely many even degree variables can occur as the singular cohomology of a space with coefficients in R, a 1960 question of N. E. Steenrod, for a commutative ring R satisfying mild conditions. In the fundamental case R = Z, our result states that the only polynomial cohomology rings over Z which can occur, are tensor products of copies of H^*(CP^\infty;Z) = Z[x_2], H^*(BSU(n);Z) = Z[x_4,x_6,...,x_{2n}], and H^*(BSp(n):Z) = Z[x_4,x_8,...,x_{4n}] confirming an old conjecture. Our classification extends Notbohm's solution for R = F_p, p odd. Odd degree generators, excluded above, only occur if R is an F_2-algebra and in that case the recent classification of 2-compact groups by the authors can be used instead of the present paper. Our proofs are short and rely on the general theory of p-compact groups, but not on classification results for these.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 19:45:21 GMT" }, { "version": "v2", "created": "Sat, 8 Mar 2008 02:47:18 GMT" }, { "version": "v3", "created": "Mon, 4 Aug 2008 17:12:16 GMT" } ]
2008-12-30T00:00:00
[ [ "Andersen", "Kasper K. S.", "" ], [ "Grodal", "Jesper", "" ] ]
0704.4003
Mikhail Bondarko
M.V. Bondarko
Weight structures vs. $t$-structures; weight filtrations, spectral sequences, and complexes (for motives and in general)
Section 4.6 was corrected
Journal of K-theory, Volume 6, Issue 03, pp. 387-504, 2010
10.1017/is010012005jkt083
null
math.KT math.AG math.AT
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper is dedicated to triangulated categories endowed with weight structures (a new notion; D. Pauksztello has independently introduced them as co-t-structures). This axiomatizes the properties of stupid truncations of complexes in $K(B)$. We also construct weight structures for Voevodsky's categories of motives and for various categories of spectra. A weight structure $w$ defines Postnikov towers of objects; these towers are canonical and functorial 'up to morphisms that are zero on cohomology'. For $Hw$ being the heart of $w$ (in $DM_{gm}$ we have $Hw=Chow$) we define a canonical conservative 'weakly exact' functor $t$ from our $C$ to a certain weak category of complexes $K_w(Hw)$. For any (co)homological functor $H:C\to A$ for an abelian $A$ we construct a weight spectral sequence $T:H(X^i[j])\implies H(X[i+j])$ where $(X^i)=t(X)$; it is canonical and functorial starting from $E_2$. This spectral sequences specializes to the 'usual' (Deligne's) weight spectral sequences for 'classical' realizations of motives and to Atiyah-Hirzebruch spectral sequences for spectra. Under certain restrictions, we prove that $K_0(C)\cong K_0(Hw)$ and $K_0(End C)\cong K_0(End Hw)$. The definition of a weight structure is almost dual to those of a t-structure; yet several properties differ. One can often construct a certain $t$-structure which is 'adjacent' to $w$ and vice versa. This is the case for the Voevodsky's $DM^{eff}_-$ (one obtains certain new Chow weight and t-structures for it; the heart of the latter is 'dual' to $Chow^{eff}$) and for the stable homotopy category. The Chow t-structure is closely related to unramified cohomology.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 19:53:00 GMT" }, { "version": "v2", "created": "Mon, 16 Jul 2007 18:41:53 GMT" }, { "version": "v3", "created": "Mon, 19 Nov 2007 18:34:08 GMT" }, { "version": "v4", "created": "Mon, 7 Jul 2008 19:41:14 GMT" }, { "version": "v5", "created": "Mon, 15 Dec 2008 20:47:24 GMT" }, { "version": "v6", "created": "Mon, 22 Jun 2009 09:19:14 GMT" }, { "version": "v7", "created": "Sat, 3 Jul 2010 00:25:05 GMT" }, { "version": "v8", "created": "Mon, 17 Jan 2011 20:38:49 GMT" }, { "version": "v9", "created": "Fri, 18 Mar 2016 17:09:55 GMT" } ]
2016-03-21T00:00:00
[ [ "Bondarko", "M. V.", "" ] ]
0705.0001
Aravind Natarajan
Aravind Natarajan and Pierre Sikivie
Does the Second Caustic Ring of Dark Matter Cause the Monoceros Ring of Stars ?
21 pages, 3 figures
Phys.Rev.D76:023505,2007
10.1103/PhysRevD.76.023505
null
astro-ph
null
Caustic rings of dark matter were predicted to exist in the plane of the Galaxy at radii $a_n \simeq 40 {\rm kpc}/n$ for $n = 1,2,3 ..$. The recently discovered Monoceros Ring of stars is located near the $n=2$ caustic, prompting us to consider a possible connection between these two objects. We identify two processes through which the Monoceros Ring of stars may have formed. One process is the migration of gas to an angular velocity minimum at the caustic leading to enhanced star formation there. The other is the adiabatic deformation of star orbits as the caustic slowly grows in mass and radius. The second process predicts an order 100% enhancement of the density of disk stars at the location of the caustic ring.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:09:05 GMT" } ]
2008-12-18T00:00:00
[ [ "Natarajan", "Aravind", "" ], [ "Sikivie", "Pierre", "" ] ]
0705.0002
Suzanne Bisschop
S. E. Bisschop, G. W. Fuchs, A. C. A. Boogert, E. F. van Dishoeck, H. Linnartz
Infrared spectroscopy of HCOOH in interstellar ice analogues
11 pages, 10 figures, accepted by A&A
null
10.1051/0004-6361:20077464
null
astro-ph
null
Context: HCOOH is one of the more common species in interstellar ices with abundances of 1-5% with respect to solid H2O. Aims: This study aims at characterizing the HCOOH spectral features in astrophysically relevant ice mixtures in order to interpret astronomical data. Methods: The ices are grown under high vacuum conditions and spectra are recorded in transmission using a Fourier transform infrared spectrometer. Pure HCOOH ices deposited at 15 K and 145 K are studied, as well as binary and tertiary mixtures containing H2O, CO, CO2 and CH3OH. The mixture concentrations are varied from 50:50% to ~10:90% for HCOOH:H2O. Binary mixtures of HCOOH:X and tertiary mixtures of HCOOH:H2O:X with X = CO, CO2, and CH3OH, are studied for concentrations of ~10:90% and ~7:67:26%, respectively. Results: Pure HCOOH ice spectra show broad bands which split around 120 K due to the conversion of a dimer to a chain-structure. Broad single component bands are found for mixtures with H2O. Additional spectral components are present in mixtures with CO, CO2 and CH3OH. The resulting peak position, full width at half maximum and band strength depend strongly on ice structure, temperature, matrix constituents and the HCOOH concentration. Comparison of the solid HCOOH 5.9, 7.2, and 8.1 micron features with astronomical data toward the low mass source HH 46 and high mass source W 33A shows that spectra of binary mixtures do not reproduce the observed ice features. However, our tertiary mixtures especially with CH3OH match the astronomical data very well. Thus interstellar HCOOH is most likely present in tertiary or more complex mixtures with H2O, CH3OH and potentially also CO or CO2, providing constraints on its formation.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:07:04 GMT" } ]
2009-11-13T00:00:00
[ [ "Bisschop", "S. E.", "" ], [ "Fuchs", "G. W.", "" ], [ "Boogert", "A. C. A.", "" ], [ "van Dishoeck", "E. F.", "" ], [ "Linnartz", "H.", "" ] ]
0705.0003
Christopher J. Burke
Christopher J. Burke, P. R. McCullough, Jeff A. Valenti, Christopher M. Johns-Krull, Kenneth A. Janes, J. N. Heasley, F. J. Summers, J. E. Stys, R. Bissinger, Michael L. Fleenor, Cindy N. Foote, Enrique Garcia-Melendo, Bruce L. Gary, P. J. Howell, F. Mallia, G. Masi, B. Taylor, T. Vanmunster
XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary
14 pages, 10 Figures, Accepted in ApJ. Negligible changes to XO-2 system properties. Removed Chi^2 light curve analysis section, and simplified MCMC light curve analysis discussion
null
10.1086/523087
null
astro-ph
null
We report on a V=11.2 early K dwarf, XO-2 (GSC 03413-00005), that hosts a Rp=0.98+0.03/-0.01 Rjup, Mp=0.57+/-0.06 Mjup transiting extrasolar planet, XO-2b, with an orbital period of 2.615857+/-0.000005 days. XO-2 has high metallicity, [Fe/H]=0.45+/-0.02, high proper motion, mu_tot=157 mas/yr, and has a common proper motion stellar companion with 31" separation. The two stars are nearly identical twins, with very similar spectra and apparent magnitudes. Due to the high metallicity, these early K dwarf stars have a mass and radius close to solar, Ms=0.98+/-0.02 Msolar and Rs=0.97+0.02/-0.01 Rsolar. The high proper motion of XO-2 results from an eccentric orbit (Galactic pericenter, Rper<4 kpc) well confined to the Galactic disk (Zmax~100 pc). In addition, the phase space position of XO-2 is near the Hercules dynamical stream, which points to an origin of XO-2 in the metal-rich, inner Thin Disk and subsequent dynamical scattering into the solar neighborhood. We describe an efficient Markov Chain Monte Carlo algorithm for calculating the Bayesian posterior probability of the system parameters from a transit light curve.
[ { "version": "v1", "created": "Tue, 1 May 2007 15:11:54 GMT" }, { "version": "v2", "created": "Wed, 12 Sep 2007 19:36:09 GMT" } ]
2009-11-13T00:00:00
[ [ "Burke", "Christopher J.", "" ], [ "McCullough", "P. R.", "" ], [ "Valenti", "Jeff A.", "" ], [ "Johns-Krull", "Christopher M.", "" ], [ "Janes", "Kenneth A.", "" ], [ "Heasley", "J. N.", "" ], [ "Summers", "F. J.", "" ], [ "Stys", "J. E.", "" ], [ "Bissinger", "R.", "" ], [ "Fleenor", "Michael L.", "" ], [ "Foote", "Cindy N.", "" ], [ "Garcia-Melendo", "Enrique", "" ], [ "Gary", "Bruce L.", "" ], [ "Howell", "P. J.", "" ], [ "Mallia", "F.", "" ], [ "Masi", "G.", "" ], [ "Taylor", "B.", "" ], [ "Vanmunster", "T.", "" ] ]
0705.0004
David Spiegel
David S. Spiegel, Zoltan Haiman, B. Scott Gaudi
On constraining a transiting exoplanet's rotation rate with its transit spectrum
33 pages, 5 figures, 5 tables, accepted by ApJ
null
10.1086/521921
null
astro-ph
null
We investigate the effect of planetary rotation on the transit spectrum of an extrasolar giant planet. During ingress and egress, absorption features arising from the planet's atmosphere are Doppler shifted by of order the planet's rotational velocity (~1-2 km/s) relative to where they would be if the planet were not rotating. We focus in particular on the case of HD209458b, which ought to be at least as good a target as any other known transiting planet. For HD209458b, this shift should give rise to a small net centroid shift of ~60 cm/s on the stellar absorption lines. Using a detailed model of the transmission spectrum due to a rotating star transited by a rotating planet with an isothermal atmosphere, we simulate the effect of the planet's rotation on the shape of the spectral lines, and in particular on the magnitude of their width and centroid shift. We then use this simulation to determine the expected signal-to-noise ratio for distinguishing a rotating from a non-rotating planet, and assess how this S/N scales with various parameters of HD209458b. We find that with a 6 m telescope, an equatorial rotational velocity of ~2 km/s could be detected with a S/N~5 by accumulating the signal over many transits over the course of several years. With a 30 m telescope, the time required to make such a detection reduces to less than 2 months.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:04:20 GMT" }, { "version": "v2", "created": "Mon, 23 Jul 2007 07:43:45 GMT" } ]
2009-11-13T00:00:00
[ [ "Spiegel", "David S.", "" ], [ "Haiman", "Zoltan", "" ], [ "Gaudi", "B. Scott", "" ] ]
0705.0005
Gouranga Nayak
Gouranga C. Nayak (SUNY, Stony Brook)
Path Integration in QCD with Arbitrary Space-Dependent Static Color Potential
11 pages latex, typos corrected, Accepted for Publication in Journal of High Energy Physics
JHEP 0903:051,2009
10.1088/1126-6708/2009/03/051
YITP-SB-07-17
hep-th hep-lat hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We perform path integral for a quark (antiquark) in the presence of an arbitrary space-dependent static color potential A^a_0(x)(=-\int dx E^a(x)) with arbitrary color index a=1,2,...8 in SU(3) and obtain an exact non-perturbative expression for the generating functional. We show that such a path integration is possible even if one can not solve the Dirac equation in the presence of arbitrary space-dependent potential. It may be possible to further explore this path integral technique to study non-perturbative bound state formation.
[ { "version": "v1", "created": "Tue, 1 May 2007 19:49:11 GMT" }, { "version": "v2", "created": "Tue, 8 May 2007 16:15:12 GMT" }, { "version": "v3", "created": "Fri, 13 Feb 2009 19:01:01 GMT" } ]
2009-03-12T00:00:00
[ [ "Nayak", "Gouranga C.", "", "SUNY, Stony Brook" ] ]
0705.0006
Mauricio Mondragon
Mauricio Mondragon, Alejandro Perez, Carlo Rovelli
Multiple-event probability in general-relativistic quantum mechanics: a discrete model
null
Phys.Rev.D76:064005,2007
10.1103/PhysRevD.76.064005
null
gr-qc
null
We introduce a simple quantum mechanical model in which time and space are discrete and periodic. These features avoid the complications related to continuous-spectrum operators and infinite-norm states. The model provides a tool for discussing the probabilistic interpretation of generally-covariant quantum systems, without the confusion generated by spurious infinities. We use the model to illustrate the formalism of general-relativistic quantum mechanics, and to test the definition of multiple-event probability introduced in a companion paper. We consider a version of the model with unitary time-evolution and a version without unitary time-evolution
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:07:22 GMT" } ]
2008-11-26T00:00:00
[ [ "Mondragon", "Mauricio", "" ], [ "Perez", "Alejandro", "" ], [ "Rovelli", "Carlo", "" ] ]
0705.0007
Hector Bombin
H. Bombin, M.A. Martin-Delgado
An Interferometry-Free Protocol for Demonstrating Topological Order
revtex4, 6 color figures
Phys.Rev.B78:165128,2008
10.1103/PhysRevB.78.165128
null
cond-mat.str-el hep-th quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose a protocol to demonstrate the topological order of a spin-1/2 lattice model with four-body interactions. Unlike other proposals, it does not rely on the controlled movement of quasiparticles, thus eliminating the addressing, decoherence and dynamical phase problems related to them. Rather, the protocol profits from the degeneracy of the ground state. It involves the addition of Zeeman terms to the original Hamiltonian that are used to create holes and move them around in the system.
[ { "version": "v1", "created": "Tue, 1 May 2007 09:08:48 GMT" }, { "version": "v2", "created": "Thu, 6 Nov 2008 18:27:17 GMT" } ]
2010-01-15T00:00:00
[ [ "Bombin", "H.", "" ], [ "Martin-Delgado", "M. A.", "" ] ]
0705.0008
Nikolaos Prezas
Jean-Pierre Derendinger, P. Marios Petropoulos and Nikolaos Prezas
Axionic symmetry gaugings in N=4 supergravities and their higher-dimensional origin
21+1 pages; v2 minor corrections, version to appear in NPB; v3 acknowledgment added
Nucl.Phys.B785:115-134,2007
10.1016/j.nuclphysb.2007.06.021
null
hep-th
null
We study the class of four-dimensional N=4 supergravities obtained by gauging the axionic shift and axionic rescaling symmetries. We formulate these theories using the machinery of embedding tensors, characterize the full gauge algebras and discuss several specific features of this family of gauged supergravities. We exhibit in particular a generalized duality between massive vectors and massive two-forms in four dimensions, inherited from the gauging of the shift symmetry. We show that these theories can be deduced from higher dimensions by a Scherk-Schwarz reduction, where a twist with respect to a non-compact symmetry is required. The four-dimensional generalized duality plays a crucial role in identifying the higher-dimensional ascendent.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:15:18 GMT" }, { "version": "v2", "created": "Thu, 19 Jul 2007 09:07:25 GMT" }, { "version": "v3", "created": "Thu, 31 Jan 2008 09:52:39 GMT" } ]
2008-11-26T00:00:00
[ [ "Derendinger", "Jean-Pierre", "" ], [ "Petropoulos", "P. Marios", "" ], [ "Prezas", "Nikolaos", "" ] ]
0705.0009
Dieter Horns
D. Horns (1), A.I.D. Hoffmann (1), A. Santangelo (1), F.A. Aharonian (2), G.P. Rowell (3) ((1) Institute for Astronomy and Astrophysics, University of T\"ubingen, Germany (2) Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany (3) School of Chemistry and Physics, University of Adelaide, Australia)
XMM-Newton observations of the first unidentified TeV gamma-ray source TeV J2032+4130
5 Pages, 3 Figures, accepted for publication in A&A
null
10.1051/0004-6361:20066836
null
astro-ph
null
(abridged) The first unidentified very high energy gamma ray source (TeV J2032+4130) in the Cygnus region has been the subject of intensive search for a counterpart source at other wavelengths. A deep ($\approx 50$ ksec) exposure of TeV J2032+4130 with \textit{XMM-Newton} has been obtained. The contribution of point sources to the observed X-ray emission from TeV J2032+4130 is subtracted from the data. The point-source subtracted X-ray data are analyzed using blank sky exposures and regions adjacent to the position of TeV J2032+4130 in the field of view covered by the XMM-Newton telescopes to search for diffuse X-ray emission. An extended X-ray emission region with a full width half maximum (FWHM) size of $\approx 12$ arc min is found. The centroid of the emission is co-located with the position of TeV J2032+4130.The energy spectrum of the emission coinciding with the position and extension of TeV J2032+4130 can be modeled by a power-law model with a photon index $\Gamma=1.5\pm0.2_\mathrm{stat}\pm0.3_\mathrm{sys}$ and an energy flux integrated between 2 and 10 keV of $f_{2-10 \mathrm{keV}} \approx 7\cdot 10^{-13}$ ergs/(cm$^2$ s) which is lower than the very high energy gamma-ray flux observed from TeV J2032+4130. We conclude that the faint extended X-ray emission discovered in this observation is the X-ray counterpart of TeV J2032+4130. Formally, it can not be excluded that the extended emission is due to an unrelated population of faint, hot ($k_BT\approx 10$ keV) unresolved point-sources which by chance coincides with the position and extension of TeV J2032+4130. We discuss our findings in the frame of both hadronic and leptonic gamma-ray production scenarios.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:31:30 GMT" } ]
2009-11-13T00:00:00
[ [ "Horns", "D.", "" ], [ "Hoffmann", "A. I. D.", "" ], [ "Santangelo", "A.", "" ], [ "Aharonian", "F. A.", "" ], [ "Rowell", "G. P.", "" ] ]
0705.0010
Sergey Dorogovtsev
S. N. Dorogovtsev, A. V. Goltsev, J. F. F. Mendes
Critical phenomena in complex networks
Review article, 79 pages, 43 figures, 1 table, 508 references, extended
Rev. Mod. Phys. 80, 1275 (2008)
10.1103/RevModPhys.80.1275
null
cond-mat.stat-mech cs.NI math-ph math.MP physics.soc-ph
null
The combination of the compactness of networks, featuring small diameters, and their complex architectures results in a variety of critical effects dramatically different from those in cooperative systems on lattices. In the last few years, researchers have made important steps toward understanding the qualitatively new critical phenomena in complex networks. We review the results, concepts, and methods of this rapidly developing field. Here we mostly consider two closely related classes of these critical phenomena, namely structural phase transitions in the network architectures and transitions in cooperative models on networks as substrates. We also discuss systems where a network and interacting agents on it influence each other. We overview a wide range of critical phenomena in equilibrium and growing networks including the birth of the giant connected component, percolation, k-core percolation, phenomena near epidemic thresholds, condensation transitions, critical phenomena in spin models placed on networks, synchronization, and self-organized criticality effects in interacting systems on networks. We also discuss strong finite size effects in these systems and highlight open problems and perspectives.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:21:37 GMT" }, { "version": "v2", "created": "Tue, 1 May 2007 22:31:15 GMT" }, { "version": "v3", "created": "Tue, 30 Oct 2007 18:12:18 GMT" }, { "version": "v4", "created": "Fri, 9 Nov 2007 16:57:31 GMT" }, { "version": "v5", "created": "Tue, 13 Nov 2007 20:57:23 GMT" }, { "version": "v6", "created": "Fri, 16 Nov 2007 21:46:13 GMT" } ]
2009-11-13T00:00:00
[ [ "Dorogovtsev", "S. N.", "" ], [ "Goltsev", "A. V.", "" ], [ "Mendes", "J. F. F.", "" ] ]
0705.0011
Brad Marston
J. B. Marston, E. Conover, and Tapio Schneider
Statistics of an Unstable Barotropic Jet from a Cumulant Expansion
23 pages, 8 figures. Version to appear in J. Atmos. Sci
J. Atmos. Sci. 65, 1955 -- 1966 (2008)
10.1175/2007JAS2510.1
null
physics.flu-dyn cond-mat.stat-mech nlin.CD physics.ao-ph physics.comp-ph
null
Low-order equal-time statistics of a barotropic flow on a rotating sphere are investigated. The flow is driven by linear relaxation toward an unstable zonal jet. For relatively short relaxation times, the flow is dominated by critical-layer waves. For sufficiently long relaxation times, the flow is turbulent. Statistics obtained from a second-order cumulant expansion are compared to those accumulated in direct numerical simulations, revealing the strengths and limitations of the expansion for different relaxation times.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:48:22 GMT" }, { "version": "v2", "created": "Thu, 1 Nov 2007 18:21:29 GMT" } ]
2016-09-08T00:00:00
[ [ "Marston", "J. B.", "" ], [ "Conover", "E.", "" ], [ "Schneider", "Tapio", "" ] ]
0705.0012
Daniel Silver
Mikami Hirasawa, Kunio Murasugi, Daniel S. Silver
When does a satellite knot fiber?
11 pages, 8 figures
null
null
null
math.GT
null
Necessary and sufficient conditions are given for a satellite knot to be fibered. Any knot $\tilde k$ embeds in an unknotted solid torus $\tilde V$ with arbitrary winding number in such a way that no satellite knot with pattern $(\tilde V, \tilde k)$ is fibered. In particular, there exist nonfibered satellite knots with fibered pattern and companion knots and nonzero winding number.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:23:12 GMT" } ]
2007-05-23T00:00:00
[ [ "Hirasawa", "Mikami", "" ], [ "Murasugi", "Kunio", "" ], [ "Silver", "Daniel S.", "" ] ]
0705.0013
Ian Ellwood
Ian Ellwood
Rolling to the tachyon vacuum in string field theory
16 pages, 5 figures, References and comments added
JHEP0712:028,2007
10.1088/1126-6708/2007/12/028
null
hep-th
null
We argue that the rolling-tachyon solution in cubic OSFT proceeds at late times to precisely the analytic tachyon-vacuum solution constructed by Schnabl. In addition, we demonstrate the relationship between the rolling-tachyon solution and the standard BCFT description by showing that there is a finite gauge transformation which relates the two.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 21:33:12 GMT" }, { "version": "v2", "created": "Tue, 25 Sep 2007 01:04:58 GMT" } ]
2008-11-26T00:00:00
[ [ "Ellwood", "Ian", "" ] ]
0705.0014
Elena Gallo
Elena Gallo (UCSB)
Galactic X-ray binary jets
Refereed version, accepted for publication in Astrophysics & Space Science
Astrophys.Space Sci.311:161-165,2007
10.1007/s10509-007-9571-z
null
astro-ph
null
With their relatively fast variability time-scales, Galactic X-ray binaries provide an excellent laboratory to explore the physics of accretion and related phenomena, most notably outflows, over different regimes. After comparing the phenomenology of jets in black hole X-ray binary systems to that of neutron stars, here I discuss the role of the jet at very low Eddington ratios, and present preliminary results obtained by fitting the broadband spectral energy distribution of a quiescent black hole binary with a `maximally jet-dominated' model.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:31:08 GMT" }, { "version": "v2", "created": "Tue, 26 Jun 2007 16:40:30 GMT" } ]
2009-06-23T00:00:00
[ [ "Gallo", "Elena", "", "UCSB" ] ]
0705.0015
Miles P. Blencowe
M. Chu, R. E. Rudd, M. P. Blencowe
The Role of Reconstructed Surfaces in the Intrinsic Dissipative Dynamics of Silicon Nanoresonators
4 pages, 5 figures
null
null
null
cond-mat.mtrl-sci
null
Dissipation in the flexural dynamics of doubly clamped nanomechanical bar resonators is investigated using molecular dynamics simulation. The dependence of the quality factor Q on temperature and the size of the resonator is calculated from direct simulation of the oscillation of a series of Si <001> bars with bare {100} dimerized surfaces. The bar widths range from 3.3 to 8.7nm, all with a fixed length of 22nm. The fundamental mode frequencies range from 40 to 90GHz and Q from 10^2 near 1000K to 10^4 near 50K. The quality factor is shown to be limited by defects in the reconstructed surface.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:34:59 GMT" } ]
2007-05-23T00:00:00
[ [ "Chu", "M.", "" ], [ "Rudd", "R. E.", "" ], [ "Blencowe", "M. P.", "" ] ]
0705.0016
Mukund Rangamani
Veronika E. Hubeny, Mukund Rangamani, Tadashi Takayanagi
A Covariant Holographic Entanglement Entropy Proposal
71 pages, 12 figures. v2: minor changes. v3: erratum in definition of causal construction fixed
JHEP0707:062,2007
10.1088/1126-6708/2007/07/062
null
hep-th cond-mat.stat-mech gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
With an aim towards understanding the time-dependence of entanglement entropy in generic quantum field theories, we propose a covariant generalization of the holographic entanglement entropy proposal of hep-th/0603001. Apart from providing several examples of possible covariant generalizations, we study a particular construction based on light-sheets, motivated in similar spirit to the covariant entropy bound underlying the holographic principle. In particular, we argue that the entanglement entropy associated with a specified region on the boundary in the context of the AdS/CFT correspondence is given by the area of a co-dimension two bulk surface with vanishing expansions of null geodesics. We demonstrate our construction with several examples to illustrate its reduction to the holographic entanglement entropy proposal in static spacetimes. We further show how this proposal may be used to understand the time evolution of entanglement entropy in a time varying QFT state dual to a collapsing black hole background. Finally, we use our proposal to argue that the Euclidean wormhole geometries with multiple boundaries should be regarded as states in a non-interacting but entangled set of QFTs, one associated to each boundary.
[ { "version": "v1", "created": "Tue, 1 May 2007 15:54:13 GMT" }, { "version": "v2", "created": "Wed, 25 Jul 2007 17:48:28 GMT" }, { "version": "v3", "created": "Thu, 14 Jun 2012 13:23:35 GMT" } ]
2012-06-15T00:00:00
[ [ "Hubeny", "Veronika E.", "" ], [ "Rangamani", "Mukund", "" ], [ "Takayanagi", "Tadashi", "" ] ]
0705.0017
George Viamontes Ph.D.
George F. Viamontes, Igor L. Markov, John P. Hayes
Checking Equivalence of Quantum Circuits and States
9 pages, 13 figures, 3 tables
Proc. Int'l Conf. on Computer-Aided Design (ICCAD), pp. 69-74, San Jose, CA, November 2007.
null
null
quant-ph cs.ET
null
Quantum computing promises exponential speed-ups for important simulation and optimization problems. It also poses new CAD problems that are similar to, but more challenging, than the related problems in classical (non-quantum) CAD, such as determining if two states or circuits are functionally equivalent. While differences in classical states are easy to detect, quantum states, which are represented by complex-valued vectors, exhibit subtle differences leading to several notions of equivalence. This provides flexibility in optimizing quantum circuits, but leads to difficult new equivalence-checking issues for simulation and synthesis. We identify several different equivalence-checking problems and present algorithms for practical benchmarks, including quantum communication and search circuits, which are shown to be very fast and robust for hundreds of qubits.
[ { "version": "v1", "created": "Tue, 1 May 2007 16:31:12 GMT" }, { "version": "v2", "created": "Tue, 1 May 2007 20:48:43 GMT" } ]
2011-11-04T00:00:00
[ [ "Viamontes", "George F.", "" ], [ "Markov", "Igor L.", "" ], [ "Hayes", "John P.", "" ] ]
0705.0018
Volker Weinberg
E.-M. Ilgenfritz (Humboldt-U. Berlin), K. Koller (LMU Muenchen), Y. Koma (U. Mainz), G. Schierholz (DESY Hamburg, NIC Zeuthen), T. Streuer (U. Kentucky), V. Weinberg (DESY Zeuthen)
Exploring the structure of the quenched QCD vacuum with overlap fermions
68 pages, 31 figures, file size: 1.7 MB (PDF)
Phys.Rev.D76:034506,2007
10.1103/PhysRevD.76.034506
DESY 07-055, HU-EP-07/08, LMU-ASC 79/06, MKPH-T-07-05
hep-lat hep-ph hep-th
null
Overlap fermions have an exact chiral symmetry on the lattice and are thus an appropriate tool for investigating the chiral and topological structure of the QCD vacuum. We study various chiral and topological aspects of quenched gauge field configurations. This includes the localization and chiral properties of the eigenmodes, the local structure of the ultraviolet filtered field strength tensor, as well as the structure of topological charge fluctuations. We conclude that the vacuum has a multifractal structure.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:32:04 GMT" } ]
2008-11-26T00:00:00
[ [ "Ilgenfritz", "E. -M.", "", "Humboldt-U. Berlin" ], [ "Koller", "K.", "", "LMU Muenchen" ], [ "Koma", "Y.", "", "U. Mainz" ], [ "Schierholz", "G.", "", "DESY Hamburg, NIC Zeuthen" ], [ "Streuer", "T.", "", "U.\n Kentucky" ], [ "Weinberg", "V.", "", "DESY Zeuthen" ] ]
0705.0019
Alexander Petrov Nikolaevich
A.N.Petrov
Nonlinear Perturbations and Conservation Laws on Curved Backgrounds in GR and Other Metric Theories
81 pages, LaTeX, 5 figures
The Chapter 2 in the book: "Classical and Quantum Gravity Research", Eds: M.N. Christiansen and T.K. Rasmussen (Nova Science Publishers, N.Y., 2008), p.p. 79 - 160
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The field-theoretical approach is reviewed. Perturbations in general relativity as well as in an arbitrary $D$-dimensional metric theory are studied on a background, which is a solution (arbitrary) of the theory. Lagrangian for perturbations is defined, and field equations for perturbations are derived from the variational principle. These equations are exact and equivalent to the equations in the standard formulation, but can be approximate also. The field-theoretical description is invariant under gauge (inner) transformations, which can be presented both in exact and approximate forms. Following the usual field-theoretical prescription, conserved quantities for perturbations are constructed. Conserved currents are expressed through divergences of superpotentials -- antisymmetric tensor densities. This form allows to relate a necessity to consider local properties of perturbations with a theoretical representation of the quasi-local nature of conserved quantities in metric theories. Applications of the formalism in general relativity are discussed. Generalized formulae for an arbitrary metric $D$-dimensional theory are tested in the Einstein-Gauss-Bonnet gravity.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 20:53:41 GMT" }, { "version": "v2", "created": "Thu, 16 Oct 2008 10:30:35 GMT" } ]
2008-10-16T00:00:00
[ [ "Petrov", "A. N.", "" ] ]
0705.0020
Jenny Greene
Jenny E. Greene (Princeton), Luis C. Ho (Carnegie Observatories)
The Mass Function of Active Black Holes in the Local Universe
to appear in ApJ; 19 pages, 13 figures
Astrophys.J.667:131-148,2007; Erratum-ibid.704:1743-1747,2009
10.1086/520497 10.1088/0004-637X/704/2/1743
null
astro-ph
null
We present the first measurement of the black hole (BH) mass function for broad-line active galaxies in the local Universe. Using the ~9000 broad-line active galaxies from the Fourth Data Release of the Sloan Digital Sky Survey, we construct a broad-line luminosity function that agrees very well with the local soft X-ray luminosity function. Using standard virial relations, we then convert observed broad-line luminosities and widths into BH masses. A mass function constructed in this way has the unique capability to probe the mass region <10^6 M_sun, which, while insignificant in terms of total BH mass density, nevertheless may place important constraints on the mass distribution of seed BHs in the early Universe. The characteristic local active BH has a mass of ~10^7 M_sun radiating at 10% of the Eddington rate. The active fraction is a strong function of BH mass; at both higher and lower masses the active mass function falls more steeply than one would infer from the distribution of bulge luminosity. The deficit of local massive radiating BHs is a well-known phenomenon, while we present the first robust measurement of a decline in the space density of active BHs at low mass.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 21:40:31 GMT" } ]
2011-02-11T00:00:00
[ [ "Greene", "Jenny E.", "", "Princeton" ], [ "Ho", "Luis C.", "", "Carnegie Observatories" ] ]
0705.0021
Lorenzo Ravagli
L. Ravagli and R. Rapp
Quark Coalescence based on a Transport Equation
7 pages, 6 figures
Phys.Lett.B655:126-131,2007
10.1016/j.physletb.2007.07.043
null
hep-ph nucl-ex nucl-th
null
We employ the Boltzmann equation for describing hadron production from a quark-gluon plasma (QGP) in ultrarelativistic heavy-ion collisions. We propose resonance formation in quark-antiquark scattering as the dominant meson-production channel, which, in particular, ensures that energy is conserved in the recombination process. This, in turn, facilitates a more controlled extension of hadronization to low transverse momenta ($p_T$), and to address the experimentally observed transition from a hydrodynamic regime to constituent quark-number scaling (CQNS). Based on input distributions for strange and charm quarks with azimuthal asymmetries, $v_2(p_T)$, characteristic for RHIC energies, we recover CQNS at sufficiently high $p_T$, while at low $p_T$ a scaling with transverse kinetic energy is found, reminiscent to experiment. The dependence of the transition regime on microscopic QGP properties, i.e. resonance widths and $Q$-values in the $q+\bar q \to M$ process, is elucidated.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 21:43:54 GMT" } ]
2008-11-26T00:00:00
[ [ "Ravagli", "L.", "" ], [ "Rapp", "R.", "" ] ]
0705.0022
Michael Gutperle
Eric D'Hoker, John Estes and Michael Gutperle
Exact half-BPS Type IIB interface solutions I: Local solution and supersymmetric Janus
LaTeX, 69 pages, 3 figures, v2: references added
JHEP 0706:021,2007
10.1088/1126-6708/2007/06/021
UCLA/07/TEP/09
hep-th
null
The complete Type IIB supergravity solutions with 16 supersymmetries are obtained on the manifold $AdS_4 \times S^2 \times S^2 \times \Sigma$ with $SO(2,3) \times SO(3) \times SO(3)$ symmetry in terms of two holomorphic functions on a Riemann surface $\Sigma$, which generally has a boundary. This is achieved by reducing the BPS equations using the above symmetry requirements, proving that all solutions of the BPS equations solve the full Type IIB supergravity field equations, mapping the BPS equations onto a new integrable system akin to the Liouville and Sine-Gordon theories, and mapping this integrable system to a linear equation which can be solved exactly. Amongst the infinite class of solutions, a non-singular Janus solution is identified which provides the AdS/CFT dual of the maximally supersymmetric Yang-Mills interface theory discovered recently. The construction of general classes of globally non-singular solutions, including fully back-reacted $AdS_5 \times S^5$ and supersymmetric Janus doped with D5 and/or NS5 branes, is deferred to a companion paper.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:15:23 GMT" }, { "version": "v2", "created": "Mon, 21 May 2007 18:26:57 GMT" } ]
2009-11-13T00:00:00
[ [ "D'Hoker", "Eric", "" ], [ "Estes", "John", "" ], [ "Gutperle", "Michael", "" ] ]
0705.0023
ZhengFei Wang
Z. F. Wang, Huaixiu Zheng, Q. W. Shi, Jie Chen, Qunxiang Li, J. G. Hou
Quantum Dot in Z-shaped Graphene Nanoribbon
4 pages, 3 figures
Appl. Phys. Lett. 91, 053109 (2007)
10.1063/1.2761266
null
cond-mat.mes-hall
null
Stimulated by recent advances in isolating graphene, we discovered that quantum dot can be trapped in Z-shaped graphene nanoribbon junciton. The topological structure of the junction can confine electronic states completely. By varying junction length, we can alter the spatial confinement and the number of discrete levels within the junction. In addition, quantum dot can be realized regardless of substrate induced static disorder or irregular edges of the junction. This device can be used to easily design quantum dot devices. This platform can also be used to design zero-dimensional functional nanoscale electronic devices using graphene ribbons.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 21:35:07 GMT" } ]
2015-05-13T00:00:00
[ [ "Wang", "Z. F.", "" ], [ "Zheng", "Huaixiu", "" ], [ "Shi", "Q. W.", "" ], [ "Chen", "Jie", "" ], [ "Li", "Qunxiang", "" ], [ "Hou", "J. G.", "" ] ]
0705.0024
Michael Gutperle
Eric D'Hoker, John Estes and Michael Gutperle
Exact half-BPS Type IIB interface solutions II: Flux solutions and multi-Janus
LaTeX, 64 pages, 10 figures
JHEP 0706:022,2007
10.1088/1126-6708/2007/06/022
UCLA/07/TEP/10
hep-th
null
Regularity and topology conditions are imposed on the exact Type IIB solutions on $AdS_4 \times S^2 \times S^2 \times \Sigma $ with 16 supersymmetries, which were derived in a companion paper. We construct an infinite class of regular solutions with varying dilaton, and non-zero 3-form fluxes. Our solutions may be viewed as the fully back-reacted geometries of $AdS_5 \times S^5$ (or more generally, Janus) doped with D5 and/or NS5 branes. The solutions are parametrized by the choice of an arbitrary genus $g$ hyper-elliptic Riemann surface $\Sigma $ with boundary, all of whose branch points are restricted to lie on a line. For genus 0, the Janus solution with 16 supersymmetries and 6 real parameters is recovered; its topology coincides with that of $AdS_5 \times S^5$. The genus $g\geq 1$ solutions are parametrized by a total of $4g+6$ real numbers, $2g-1$ of which are the real moduli of $\Sigma$. The solutions have $2g+2$ asymptotic $AdS_5 \times S^5$ regions, $g$ three-spheres with RR 3-form charge, and another $g$ with NSNS 3-form charge. Collapse of consecutive branch points of $\Sigma $ yields singularities which correspond to D5 and NS5 branes in the probe limit. It is argued that the AdS/CFT dual gauge theory to each of our solutions consists of a 2+1-dimensional planar interface on which terminate $2g+2$ half-Minkowski 3+1-dimensional space-time $\mathcal{N}=4$ super-Yang-Mills theories. Generally, the $\\mathcal{N}=4$ theory in each Minkowski half-space-time may have an independent value of the gauge coupling, and the interface may support various operators, whose interface couplings are further free parameters of the dual gauge theory.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 21:56:42 GMT" } ]
2017-09-07T00:00:00
[ [ "D'Hoker", "Eric", "" ], [ "Estes", "John", "" ], [ "Gutperle", "Michael", "" ] ]
0705.0025
Andreas Martin Lisewski
Andreas Martin Lisewski
Can the Internet cope with stress?
4 pages
null
null
null
cs.HC cs.AI
null
When will the Internet become aware of itself? In this note the problem is approached by asking an alternative question: Can the Internet cope with stress? By extrapolating the psychological difference between coping and defense mechanisms a distributed software experiment is outlined which could reject the hypothesis that the Internet is not a conscious entity.
[ { "version": "v1", "created": "Tue, 1 May 2007 15:44:17 GMT" } ]
2007-05-23T00:00:00
[ [ "Lisewski", "Andreas Martin", "" ] ]
0705.0026
Daniel A. Lidar
A. Hamma, W. Zhang, S. Haas, and D.A. Lidar (USC)
Entanglement, fidelity and topological entropy in a quantum phase transition to topological order
replaced with published version
Phys. Rev. B 77, 155111 (2008)
10.1103/PhysRevB.77.155111
null
quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a numerical study of a quantum phase transition from a spin-polarized to a topologically ordered phase in a system of spin-1/2 particles on a torus. We demonstrate that this non-symmetry-breaking topological quantum phase transition (TOQPT) is of second order. The transition is analyzed via the ground state energy and fidelity, block entanglement, Wilson loops, and the recently proposed topological entropy. Only the topological entropy distinguishes the TOQPT from a standard QPT, and remarkably, does so already for small system sizes. Thus the topological entropy serves as a proper order parameter. We demonstrate that our conclusions are robust under the addition of random perturbations, not only in the topological phase, but also in the spin polarized phase and even at the critical point.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 21:45:10 GMT" }, { "version": "v2", "created": "Sat, 7 Jun 2008 19:12:12 GMT" } ]
2008-06-07T00:00:00
[ [ "Hamma", "A.", "", "USC" ], [ "Zhang", "W.", "", "USC" ], [ "Haas", "S.", "", "USC" ], [ "Lidar", "D. A.", "", "USC" ] ]
0705.0027
Xiangyu Wang
Xiang-Yu Wang, Soebur Razzaque, Peter Meszaros and Zi-Gao Dai
High-energy Cosmic Rays and Neutrinos from Semi-relativistic Hypernovae
Accepted for publication in Phys. Rev. D, 6 revtex pages, 1 figure
Phys.Rev.D76:083009,2007
10.1103/PhysRevD.76.083009
null
astro-ph hep-ph
null
The origin of the ultrahigh-energy (UHE) cosmic rays (CRs) from the second knee ($\sim6\times10^{17}$eV) above in the CR spectrum is still unknown. Recently, there has been growing evidence that a peculiar type of supernovae, called hypernovae, are associated with sub-energetic gamma-ray bursts (GRBs), such as SN1998bw/GRB980425 and SN2003lw/GRB031203. Such hypernovae appear to have high (up to mildly relativistic) velocity ejecta, which may be linked to the sub-energetic GRBs. Assuming a continuous distribution of the kinetic energy of the hypernova ejecta as a function of its velocity $E_k\propto (\Gamma\beta)^{-\alpha}$ with $\alpha\sim 2$, we find that 1) the external shock wave produced by the high velocity ejecta of a hypernova can accelerate protons up to energies as high as $10^{19} {\rm eV}$; 2) the cosmological hypernova rate is sufficient to account for the energy flux above the second knee; and 3) the steeper spectrum of CRs at these energies can arise in these sources. In addition, hypernovae would also give rise to a faint diffuse UHE neutrino flux, due to $p\gamma$ interactions of the UHE CRs with hypernova optical-UV photons.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:06:17 GMT" }, { "version": "v2", "created": "Wed, 12 Sep 2007 01:59:34 GMT" } ]
2008-12-18T00:00:00
[ [ "Wang", "Xiang-Yu", "" ], [ "Razzaque", "Soebur", "" ], [ "Meszaros", "Peter", "" ], [ "Dai", "Zi-Gao", "" ] ]
0705.0028
Sean Tulin
Michael Ramsey-Musolf, Shufang Su, and Sean Tulin
Pion Leptonic Decays and Supersymmetry
12 pages, 11 figures; included additional electroweak constraints in analysis, simplified abstract, ref. added
Phys.Rev.D76:095017,2007
10.1103/PhysRevD.76.095017
Caltech MAP-331
hep-ph
null
We compute supersymmetric contributions to pion leptonic (\pi_{l2}) decays in the Minimal Supersymmetric Standard Model (MSSM). When R-parity is conserved, the largest contributions to the ratio R_{e/\mu} = \Gamma[ \pi^+ \to e^+ \nu_e(\gamma)]/\Gamma[ \pi^+ \to \mu^+ \nu_\mu(\gamma)] arise from one-loop (V-A)x(V-A) corrections. These contributions can be potentially as large as the sensitivities of upcoming experiments; if measured, they would imply significant bounds on the chargino and slepton sectors complementary to current collider limits. We also analyze R-parity violating interactions, which may produce a detectable deviation in R_{e/\mu} while remaining consistent with all other precision observables.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:43:01 GMT" }, { "version": "v2", "created": "Sun, 24 Jun 2007 20:35:23 GMT" } ]
2008-11-26T00:00:00
[ [ "Ramsey-Musolf", "Michael", "" ], [ "Su", "Shufang", "" ], [ "Tulin", "Sean", "" ] ]
0705.0029
Esteban Guevara
Esteban Guevara
EGT through Quantum Mechanics & from Statistical Physics to Economics
9 pages
null
null
null
q-fin.GN physics.soc-ph
null
By analyzing the relationships between a socioeconomical system modeled through evolutionary game theory and a physical system modeled through quantum mechanics we show how although both systems are described through two theories apparently different both are analogous and thus exactly equivalents. The extensions of quantum mechanics to statistical physics and information theory let us use some of their definitions for the best understanding of the behavior of economics and biology. The quantum analogue of the replicator dynamics is the von Neumann equation. A system in where all its members are in Nash equilibrium is equivalent to a system in a maximum entropy state. Nature is a game in where its players compete for a common welfare and the equilibrium of the system that they are members. They act as a whole besides individuals like they obey a rule in where they prefer to work for the welfare of the collective besides the individual welfare.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:14:18 GMT" } ]
2008-12-02T00:00:00
[ [ "Guevara", "Esteban", "" ] ]
0705.0030
Frederick K. Lamb
Frederick K. Lamb
High Frequency QPOs in Neutron Stars and Black Holes: Probing Dense Matter and Strong Gravitational Fields
30 pages, 8 figures, published in "From X-Ray Binaries to Gamma-ray Bursts", proceedings of a symposium held in memory of Jan van Paradijs 6-9 June 2001, eds. E.P.J. van den Heuvel, L. Kaper, E. Roi, & R.A.M.J. Wijers
ASP Conf.Ser.308:221-250,2003
null
null
astro-ph
null
Quasi-periodic oscillations (QPOs) have been discovered in the X-ray emission of many neutron stars and black holes. The QPOs with frequencies greater than about 300 Hz are thought to be produced near the surfaces of neutron stars and the event horizons of black holes. I first summarize some of the most important properties of the QPOs seen in neutron star and black hole systems. I then review some of the models that have been proposed and compare them with observational data. Finally, I describe how these QPOs can be used to determine the properties of dense matter and strong gravitational fields.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:15:44 GMT" } ]
2009-06-23T00:00:00
[ [ "Lamb", "Frederick K.", "" ] ]
0705.0031
Kiran S. Kedlaya
Kiran S. Kedlaya
Swan conductors for p-adic differential modules, II: Global variation
34 pages; v3: major revisions in 3.4, 4.3, 5.x; minor changes elsewhere
null
null
null
math.NT math.AG
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Using a local construction from a previous paper, we exhibit a numerical invariant, the differential Swan conductor, for an isocrystal on a variety over a perfect field of positive characteristic overconvergent along a boundary divisor; this leads to an analogous construction for certain p-adic and l-adic representations of the etale fundamental group of a variety. We then demonstrate some variational properties of this definition for overconvergent isocrystals, paying special attention to the case of surfaces.
[ { "version": "v1", "created": "Tue, 1 May 2007 17:52:06 GMT" }, { "version": "v2", "created": "Wed, 9 Apr 2008 14:53:09 GMT" }, { "version": "v3", "created": "Mon, 24 Nov 2008 19:50:27 GMT" } ]
2008-11-24T00:00:00
[ [ "Kedlaya", "Kiran S.", "" ] ]
0705.0032
Sergiu Vacaru I.
Sergiu I. Vacaru
Nonholonomic Algebroids, Finsler Geometry, and Lagrange-Hamilton Spaces
75 pages, latex2e, 11pt
Mathematical Sciences (Springer Open) 2012, 6: 18
10.1186/2251-7456-6-18
null
math-ph gr-qc hep-th math.DG math.MP
null
We elaborate an unified geometric approach to classical mechanics, Riemann-Finsler spaces and gravity theories on Lie algebroids provided with nonlinear connection (N-connection) structure. There are investigated the conditions when the fundamental geometric objects like the anchor, metric and linear connection, almost sympletic and related almost complex structures may be canonically defined by a N-connection induced from a regular Lagrangian (or Hamiltonian), in mechanical models, or by generic off-diagonal metric terms and nonholonomic frames, in gravity theories. Such geometric constructions are modelled on nonholonomic manifolds provided with nonintegrable distributions and related chains of exact sequences of submanifolds defining N-connections. We investigate the main properties of the Lagrange, Hamilton, Finsler-Riemann and Einstein-Cartan algebroids and construct and analyze exact solutions describing such objects.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:29:38 GMT" } ]
2012-08-10T00:00:00
[ [ "Vacaru", "Sergiu I.", "" ] ]
0705.0033
Nikos Frantzikinakis
Nikos Frantzikinakis, Randall McCutcheon
Ergodic Theory: Recurrence
Revised version. To appear in the Encyclopedia of Complexity and System Science
null
null
null
math.DS
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We survey the impact of the Poincar\'e recurrence principle in ergodic theory, especially as pertains to the field of ergodic Ramsey theory.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:32:29 GMT" }, { "version": "v2", "created": "Sat, 25 Aug 2007 14:38:23 GMT" }, { "version": "v3", "created": "Mon, 4 Nov 2019 08:58:03 GMT" } ]
2019-11-05T00:00:00
[ [ "Frantzikinakis", "Nikos", "" ], [ "McCutcheon", "Randall", "" ] ]
0705.0034
Andr\'es Navas
Andr\'es Navas
Three remarks on one dimensional bi-Lipschitz conjugacies
7 pages, no Figure
null
null
null
math.DS math.GR
null
We show that bi-Lipschitz conjugacies between non singular one dimensional systems are forced to be smooth, at least in the minimal (and ergodic) case. This is however far from being true in the non minimal case. These results clarify a classical work by Ghys and Tsuboi.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:37:26 GMT" } ]
2007-05-23T00:00:00
[ [ "Navas", "Andrés", "" ] ]
0705.0035
Bryan J. Field
B. Field (Florida State), C.B. Jackson (Brookhaven), and L. Reina (Florida State)
Higgs boson production with one bottom quark including higher-order soft-gluon corrections
revtex4, 13 pages, 11 figures; new references and additional comments
Phys.Rev.D76:074008,2007
10.1103/PhysRevD.76.074008
FSU-HEP-2007-0501, BNL-HET-07/7
hep-ph
null
A Higgs boson produced in association with one or more bottom quarks is of great theoretical and experimental interest to the high-energy community. A precise prediction of its total and differential cross-section can have a great impact on the discovery of a Higgs boson with large bottom-quark Yukawa coupling, like the scalar (h^0 and H^0) and pseudoscalar (A^0) Higgs bosons of the Minimal Supersymmetric Standard Model (MSSM) in the region of large \tan\beta. In this paper we apply the threshold resummation formalism to determine both differential and total cross-sections for b g \to b\Phi (where \Phi = h^0, H^0), including up to next-to-next-to-next-to-leading order (NNNLO) soft plus virtual QCD corrections at next-to-leading logarithmic (NLL) accuracy. We present results for both the Fermilab Tevatron and the CERN Large Hadron Collider (LHC).
[ { "version": "v1", "created": "Tue, 1 May 2007 19:58:20 GMT" }, { "version": "v2", "created": "Thu, 12 Jul 2007 17:09:25 GMT" } ]
2008-11-26T00:00:00
[ [ "Field", "B.", "", "Florida State" ], [ "Jackson", "C. B.", "", "Brookhaven" ], [ "Reina", "L.", "", "Florida State" ] ]
0705.0036
Victor Goncalves
C. Brenner Mariotto, V. P. Goncalves
Enhancement of prompt photons in ultrarelativistic proton-proton collisions from nonlinear gluon evolution at small-$x$
4 pages, 4 figures. Version to be published in Physical Review C
Phys.Rev.C75:068202,2007
10.1103/PhysRevC.75.068202
null
hep-ph
null
In this paper we estimate the influence of nonlinear gluon evolution in the production of prompt photons at the LHC pp collider. We assume the validity of collinear factorization and consider the EHKQS parton distributions, which are solutions of the GLR-MQ evolution equations and describe quite well the DESY $ep$ HERA data, as input in our calculations. We find that both single and double photon production are enhanced for low-$p_T$ photons and central rapidities, while this effect is absent for the high-$p_T$ photons. The implications of this effect for the Quark-Gluon Plasma searches and for the QCD background to Higgs are also discussed.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:47:33 GMT" }, { "version": "v2", "created": "Wed, 30 May 2007 15:20:52 GMT" } ]
2008-11-26T00:00:00
[ [ "Mariotto", "C. Brenner", "" ], [ "Goncalves", "V. P.", "" ] ]
0705.0037
Bernardo Barbiellini
R. Saniz, B. Barbiellini, P. M. Platzman, A. J. Freeman
Physisorption of positronium on quartz surfaces
5 pages, 3 figures, submitted
Phys. Rev. Lett. 99, 096101 (2007)
10.1103/PhysRevLett.99.096101
null
cond-mat.mtrl-sci cond-mat.other
null
The possibility of having positronium (Ps) physisorbed at a material surface is of great fundamental interest, since it can lead to new insight regarding quantum sticking and is a necessary first step to try to obtain a Ps$_2$ molecule on a material host. Some experiments in the past have produced evidence for physisorbed Ps on a quartz surface, but firm theoretical support for such a conclusion was lacking. We present a first-principles density-functional calculation of the key parameters determining the interaction potential between Ps and an $\alpha$-quartz surface. We show that there is indeed a bound state with an energy of 0.14 eV, a value which agrees very well with the experimental estimate of $\sim0.15$ eV. Further, a brief energy analysis invoking the Langmuir-Hinshelwood mechanism for the reaction of physisorbed atoms shows that the formation and desorption of a Ps$_2$ molecule in that picture is consistent with the above results.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:49:27 GMT" } ]
2007-10-11T00:00:00
[ [ "Saniz", "R.", "" ], [ "Barbiellini", "B.", "" ], [ "Platzman", "P. M.", "" ], [ "Freeman", "A. J.", "" ] ]
0705.0038
Ji Li
Ji Li
Prime Graphs and Exponential Composition of Species
30 pages, 7 figures, 1 table
null
null
null
math.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we enumerate prime graphs with respect to the Cartesian multiplication of graphs. We use the unique factorization of a connected graph into the product of prime graphs given by Sabidussi to find explicit formulas for labeled and unlabeled prime graphs. In the case of species, we construct the exponential composition of species based on the arithmetic product of species of Maia and M\'endez and the quotient species, and express the species of connected graphs as the exponential composition of the species of prime graphs.
[ { "version": "v1", "created": "Tue, 1 May 2007 16:51:05 GMT" }, { "version": "v2", "created": "Wed, 16 May 2007 19:33:06 GMT" }, { "version": "v3", "created": "Thu, 17 May 2007 15:49:55 GMT" }, { "version": "v4", "created": "Tue, 10 Nov 2009 05:00:47 GMT" } ]
2009-11-10T00:00:00
[ [ "Li", "Ji", "" ] ]
0705.0039
Vadim Astakhov
Vadim Astakhov
Cosmology and semi-conservation of computations in the universe
8 pages, 5 figures
null
null
null
gr-qc
null
Resent works of Hawking and Susskind suggested that information is conserved in the universe. We extend this thesis and propose that dynamics of information - computations can conserve in Anti-de-Sitter cosmological model. Information geometry formalism is proposed to analyze information in dynamical systems. We consider entropy flow as a geometrical flow on statistical manifold and develop a Dynamic Cores model to analyze migration of information in dynamical systems. Geometrical flow on the statistical manifold was considered as a transition of local dynamical systems in original d+1-dim AdS space to their delocalized holographic representation in d-dim Conformal Field Theory (CFT). It was noted that geometrical flow related to renormalization group flow and provide semi-conservation of informational invariants. Those invariants interpreted as types of computations.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:54:04 GMT" } ]
2007-05-23T00:00:00
[ [ "Astakhov", "Vadim", "" ] ]
0705.0040
Helena McGahagan
L. Dawson, H. McGahagan, G. Ponce
On the decay properties of solutions to a class of Schr\"odinger equations
null
null
null
null
math.AP
null
We construct a local in time, exponentially decaying solution of the one-dimensional variable coefficient Schrodinger equation by solving a nonstandard boundary value problem. A main ingredient in the proof is a new commutator estimate involving the projections P+ and P- onto the positive and negative frequencies.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 22:56:33 GMT" } ]
2007-05-23T00:00:00
[ [ "Dawson", "L.", "" ], [ "McGahagan", "H.", "" ], [ "Ponce", "G.", "" ] ]
0705.0041
Eli Waxman
R. Budnik, B. Katz, A. MacFadyen and E. Waxman
Cosmic rays from trans-relativistic supernovae
Accepted to ApJ. Expanded abstract, introduction, discussion
Astrophys.J.673:928-933,2008
10.1086/524923
null
astro-ph
null
We derive constraints that must be satisfied by the sources of ~10^{15} to ~10^{18} eV cosmic rays, under the assumption that the sources are Galactic. We show that while these constraints are not satisfied by ordinary supernovae (SNe), which are believed to be the sources of <10^{15} eV cosmic rays, they may be satisfied by the recently discovered class of trans-relativistic supernovae (TRSNe), which were observed in association with gamma-ray bursts. We define TRSNe as SNe that deposit a large fraction, f_R>10^{-2}, of their kinetic energy in mildly relativistic, \gamma\beta>1, ejecta. The high velocity ejecta enable particle acceleration to ~10^{18} eV, and the large value of f_R (compared to f_R~10^{-7} for ordinary SNe) ensures that if TRSNe produce the observed ~10^{18} eV cosmic ray flux, they do not overproduce the flux at lower energies. This, combined with the estimated rate and energy production of TRSNe, imply that Galactic TRSNe may be the sources of cosmic rays with energies up to ~10^{18}eV .
[ { "version": "v1", "created": "Tue, 1 May 2007 03:16:13 GMT" }, { "version": "v2", "created": "Tue, 23 Oct 2007 13:25:49 GMT" } ]
2010-11-11T00:00:00
[ [ "Budnik", "R.", "" ], [ "Katz", "B.", "" ], [ "MacFadyen", "A.", "" ], [ "Waxman", "E.", "" ] ]
0705.0042
Ji Li
Ira Gessel and Ji Li
Enumeration of Point-Determining Graphs
26 pages, 11 figures
null
null
null
math.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Point-determining graphs are graphs in which no two vertices have the same neighborhoods, co-point-determining graphs are those whose complements are point-determining, and bi-point-determining graphs are those both point-determining and co-point-determining. Bicolored point-determining graphs are point-determining graphs whose vertices are properly colored with white and black. We use the combinatorial theory of species to enumerate these graphs as well as the connected cases.
[ { "version": "v1", "created": "Tue, 1 May 2007 16:51:38 GMT" }, { "version": "v2", "created": "Tue, 10 Nov 2009 04:47:14 GMT" } ]
2009-11-10T00:00:00
[ [ "Gessel", "Ira", "" ], [ "Li", "Ji", "" ] ]
0705.0043
Christian Goulding
Savas Dayanik, Christian Goulding, H. Vincent Poor
Joint Detection and Identification of an Unobservable Change in the Distribution of a Random Sequence
Appeared in the Proceedings of the 41st Annual Conference on Information Sciences and Systems, John Hopkins University, March 2007
null
null
null
cs.IT math.IT
null
This paper examines the joint problem of detection and identification of a sudden and unobservable change in the probability distribution function (pdf) of a sequence of independent and identically distributed (i.i.d.) random variables to one of finitely many alternative pdf's. The objective is quick detection of the change and accurate inference of the ensuing pdf. Following a Bayesian approach, a new sequential decision strategy for this problem is revealed and is proven optimal. Geometrical properties of this strategy are demonstrated via numerical examples.
[ { "version": "v1", "created": "Mon, 30 Apr 2007 23:59:09 GMT" } ]
2009-04-16T00:00:00
[ [ "Dayanik", "Savas", "" ], [ "Goulding", "Christian", "" ], [ "Poor", "H. Vincent", "" ] ]
0705.0044
Shashi Kiran Chilappagari
Shashi Kiran Chilappagari and Bane Vasic
Reliable Memories Built from Unreliable Components Based on Expander Graphs
Submitted to IEEE Transactions on Information Theory
null
null
null
cs.IT math.IT
null
In this paper, memories built from components subject to transient faults are considered. A fault-tolerant memory architecture based on low-density parity-check codes is proposed and the existence of reliable memories for the adversarial failure model is proved. The proof relies on the expansion property of the underlying Tanner graph of the code. An equivalence between the Taylor-Kuznetsov (TK) scheme and Gallager B algorithm is established and the results are extended to the independent failure model. It is also shown that the proposed memory architecture has lower redundancy compared to the TK scheme. The results are illustrated with specific numerical examples.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:07:46 GMT" } ]
2007-07-13T00:00:00
[ [ "Chilappagari", "Shashi Kiran", "" ], [ "Vasic", "Bane", "" ] ]
0705.0045
Andrew LaForge
A. D. LaForge, W. J. Padilla, K. S. Burch, Z. Q. Li, S. V. Dordevic, Kouji Segawa, Yoichi Ando, D. N. Basov
Disparities in the Josephson vortex state electrodynamics of high-Tc cuprates
5 pages, 3 figures
null
null
null
cond-mat.supr-con cond-mat.str-el
null
We report on far infrared measurements of interplane conductivity for underdoped single-crystal YBa2Cu3Oy in magnetic field and situate these new data within earlier work on two other high-Tc cuprate superconductors, La(2-x)SrxCuO4 and Bi2Sr2CaCu2O(8+d). The three systems have displayed apparently disparate electrodynamic responses in the Josephson vortex state formed when magnetic field H is applied parallel to the CuO2 planes. Specifically, there is discrepancy in the number and field dependence of longitudinal modes observed. We compare and contrast these findings with several models of the electrodynamics in the vortex state and suggest that most differences can be reconciled through considerations of the Josephson vortex lattice ground state as well as the c-axis and in-plane quasiparticle dissipations.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:09:49 GMT" } ]
2007-05-23T00:00:00
[ [ "LaForge", "A. D.", "" ], [ "Padilla", "W. J.", "" ], [ "Burch", "K. S.", "" ], [ "Li", "Z. Q.", "" ], [ "Dordevic", "S. V.", "" ], [ "Segawa", "Kouji", "" ], [ "Ando", "Yoichi", "" ], [ "Basov", "D. N.", "" ] ]
0705.0046
Ronald Fisch
Ronald Fisch
Comment on "Conformal invariance and stochastic Loewner evolution processes in two-dimensional Ising spin glasses"
1 page
null
null
null
cond-mat.dis-nn cond-mat.stat-mech
null
By combining the scaling relation of Amoruso {\it et al.}, PRL {\bf 97}, 267202 (2006) with standard droplet model assumptions, a value $\theta = (\sqrt{6} - 3) / 2$ is obtained. This conjecture is reasonably consistent with the best existing numerical calculations, and may be exact.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:18:45 GMT" } ]
2007-05-23T00:00:00
[ [ "Fisch", "Ronald", "" ] ]
0705.0047
Holger F. Hofmann
Holger F. Hofmann and Takafumi Ono
High photon number path entanglement in the interference of spontaneously downconverted photon pairs with coherent laser light
5 pages, including 2 figures and 1 table, final version for publication as rapid communication in Phys. Rev. A
Phys. Rev. A 76, 031806(R) (2007)
10.1103/PhysRevA.76.031806
null
quant-ph
null
We show that the quantum interference between downconverted photon pairs and photons from coherent laser light can produce a maximally path entangled N-photon output component with a fidelity greater than 90% for arbitrarily high photon numbers. A simple beam splitter operation can thus transform the 2-photon coherence of down-converted light into an almost optimal N-photon coherence.
[ { "version": "v1", "created": "Tue, 1 May 2007 01:19:38 GMT" }, { "version": "v2", "created": "Thu, 23 Aug 2007 09:06:07 GMT" } ]
2007-10-01T00:00:00
[ [ "Hofmann", "Holger F.", "" ], [ "Ono", "Takafumi", "" ] ]
0705.0048
Rohta Takahashi
Rohta Takahashi
Horizon-Penetrating Transonic Accretion Disks around Rotating Black Holes
MNRAS accepted
null
10.1111/j.1365-2966.2007.11877.x
null
astro-ph
null
The stationary hydrodynamic equations for the transonic accretion disks and flows around rotating black holes are presented by using the Kerr-Schild coordinate where there is no coordinate singularity at the event horizon. We use two types of the causal viscosity prescription, and the boundary conditions for the transonic accretion flows are given at the sonic point. For one type of the causal viscosity prescription we also add the boundary conditions at the viscous point where the accreting radial velocity is nearly equal to the viscous diffusion velocity. Based on the formalism for the transonic accretion disks, after we present the calculation method of the transonic solutions, the horizon-penetrating transonic solutions which smoothly pass the event horizon are calculated for several types of the accretion flow models: the ideal isothermal flows, the ideal and the viscous polytropic flows, the advection dominated accretion flows (ADAFs) with the relativistic equation of state, the adiabatic accretion disks, the standard accretion disks, the supercritical accretion disks. These solutions are obtained for both non-rotating and rotating black holes. The calculated accretion flows plunge into black hole with finite three velocity smaller than the speed of light even at the event horizon or inside the horizon, and the angular velocities of the accretion flow at the horizon are generally different from the angular velocity of the frame-dragging due to the black hole's rotation. These features contrast to the results obtained by using the Boyer-Lindquist coordinate with the coordinate singularity at the horizon.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:39:33 GMT" } ]
2015-05-13T00:00:00
[ [ "Takahashi", "Rohta", "" ] ]
0705.0049
Kyungsik Kim
K. S. Kim and L. E. Wright
y-scaling in Quasielastic Electron Scattering from Nuclei
21 pages, 11 figures
Phys.Rev.C76:044613,2007
10.1103/PhysRevC.76.044613
null
nucl-th
null
A relativistic single particle model is used to calculate the inclusive $(e,e')$ reaction from $A=$12, 40, 56, 197, and 208 nuclei in the quasielastic region. We have shown that this model provides a very good description of the available experimental cross sections when they are dominated by the quasielastic process. In this paper we use this model to investigate the dependence of $y$-scaling on electron kinematics, particularly the electron scattering angle, for a range of squared four momentum transfer $0.20-0.80$ (GeV/c)$^2$. In this kinematic domain, Coulomb distortion of the electron does not significantly affect scaling, but final state interactions of the knocked out nucleon do affect scaling particularly when the nucleons have lower energies. In general, we find that scaling works for this reaction, but at lower values of the four momentum transfer, the scaling function does have some dependence on the electron scattering angle. We also consider a modification of y-scaling to include small binding energy effects as a function of Z and A and show that there is some improvement in scaling.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:44:49 GMT" }, { "version": "v2", "created": "Mon, 9 Jul 2007 07:35:28 GMT" } ]
2008-11-26T00:00:00
[ [ "Kim", "K. S.", "" ], [ "Wright", "L. E.", "" ] ]
0705.0050
Weiqiang Wang
Shun-Jen Cheng, Weiqiang Wang
Brundan-Kazhdan-Lusztig and super duality conjectures
v2, 44 pages, mild changes, clarifications on Introduction and other places
Publ. RIMS 44 (2008), 1219--1272.
null
null
math.RT math.CO math.QA
null
We formulate a general super duality conjecture on connections between parabolic categories O of modules over Lie superalgebras and Lie algebras of type A, based on a Fock space formalism of their Kazhdan-Lusztig theories which was initiated by Brundan. We show that the Brundan-Kazhdan-Lusztig (BKL) polynomials for Lie superalgebra gl(m|n) in our parabolic setup can be identified with the usual parabolic Kazhdan-Lusztig polynomials. We establish some special cases of the BKL conjecture on the parabolic category O of gl(m|n)-modules and additional results which support the BKL conjecture and super duality conjecture.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:47:48 GMT" }, { "version": "v2", "created": "Wed, 16 Apr 2008 01:23:02 GMT" } ]
2009-01-13T00:00:00
[ [ "Cheng", "Shun-Jen", "" ], [ "Wang", "Weiqiang", "" ] ]
0705.0051
A. Perez-Lorenzana
El\'i Santos, A. P\'erez-Lorenzana and Luis O. Pimentel
Radion stabilization from the vacuum on flat extra dimensions
Comments and clarifications added throughout the text. Typos corrected and references added. Final version, 27 pages, five figures included
Phys.Rev.D77:025023,2008
10.1103/PhysRevD.77.025023
null
hep-ph
null
Volume stabilization in models with flat extra dimension could follow from vacuum energy residing in the bulk when translational invariance is spontaneously broken. We study a simple toy model that exemplifies this mechanism which considers a massive scalar field with non trivial boundary conditions at the end points of the compact space, and includes contributions from brane and bulk cosmological constants. We perform our analysis in the conformal frame where the radion field, associated with volume variations, is defined, and present a general strategy for building stabilization potentials out of those ingredients. We also provide working examples for the interval and the $T^n/Z_2$ orbifold configuration.
[ { "version": "v1", "created": "Tue, 1 May 2007 00:50:25 GMT" }, { "version": "v2", "created": "Sat, 26 Jan 2008 00:57:44 GMT" } ]
2008-11-26T00:00:00
[ [ "Santos", "Elí", "" ], [ "Pérez-Lorenzana", "A.", "" ], [ "Pimentel", "Luis O.", "" ] ]
0705.0052
Richard Karnesky
Richard A. Karnesky, Dieter Isheim, David N. Seidman
Direct Measurement of 2D and 3D Interprecipitate Distance Distributions from Atom-Probe Tomographic Reconstructions
null
null
10.1063/1.2753097
null
cond-mat.mtrl-sci
null
Edge-to-edge interprecipitate distance distributions are critical for predicting precipitation strengthening of alloys and other physical phenomena. A method to calculate this 3D distance and the 2D interplanar distance from atom-probe tomographic data is presented. It is applied to nanometer-sized Cu-rich precipitates in an Fe-1.7 at.% Cu alloy. Experimental interprecipitate distance distributions are discussed.
[ { "version": "v1", "created": "Tue, 1 May 2007 01:29:34 GMT" } ]
2009-11-13T00:00:00
[ [ "Karnesky", "Richard A.", "" ], [ "Isheim", "Dieter", "" ], [ "Seidman", "David N.", "" ] ]
0705.0053
Erhan Bayraktar
Erhan Bayraktar, Virginia R. Young
Mutual Fund Theorems when Minimizing the Probability of Lifetime Ruin
null
null
null
null
q-fin.PM math.OC math.PR q-fin.RM
null
We show that the mutual fund theorems of Merton (1971) extend to the problem of optimal investment to minimize the probability of lifetime ruin. We obtain two such theorems by considering a financial market both with and without a riskless asset for random consumption. The striking result is that we obtain two-fund theorems despite the additional source of randomness from consumption.
[ { "version": "v1", "created": "Tue, 1 May 2007 01:21:40 GMT" }, { "version": "v2", "created": "Mon, 22 Oct 2007 04:22:40 GMT" }, { "version": "v3", "created": "Wed, 19 Mar 2008 21:14:45 GMT" } ]
2008-12-10T00:00:00
[ [ "Bayraktar", "Erhan", "" ], [ "Young", "Virginia R.", "" ] ]
0705.0054
Antoine Sinton
Andrea Montanari and Antoine Sinton
A simple one dimensional glassy Kac model
25 pages, 9 eps figures
J. Stat. Mech. (2007) P08004
10.1088/1742-5468/2007/08/P08004
null
cond-mat.stat-mech cond-mat.dis-nn
null
We define a new family of random spin models with one-dimensional structure, finite-range multi-spin interactions, and bounded average degree (number of interactions in which each spin participates). Unfrustrated ground states can be described as solutions of a sparse, band diagonal linear system, thus allowing for efficient numerical analysis. In the limit of infinite interaction range, we recover the so-called XORSAT (diluted p-spin) model, that is known to undergo a random first order phase transition as the average degree is increased. Here we investigate the most important consequences of a large but finite interaction range: (i) Fluctuation-induced corrections to thermodynamic quantities; (ii) The need of an inhomogeneous (position dependent) order parameter; (iii) The emergence of a finite mosaic length scale. In particular, we study the correlation length divergence at the (mean-field) glass transition.
[ { "version": "v1", "created": "Tue, 1 May 2007 01:35:30 GMT" } ]
2009-04-13T00:00:00
[ [ "Montanari", "Andrea", "" ], [ "Sinton", "Antoine", "" ] ]
0705.0055
Susan Sierra
Susan J. Sierra
A general homological Kleiman-Bertini theorem
11 pages; final version to appear in Algebra and Number Theory
null
null
null
math.AG math.RA
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Let G be a smooth algebraic group acting on a variety X. Let F and E be coherent sheaves on X. We show that if all the higher Tor sheaves of F against G-orbits vanish, then for generic g in G, the sheaf Tor^X_j(gF, E) vanishes for all j >0. This generalizes a result of Miller and Speyer for transitive group actions and a result of Speiser, itself generalizing the classical Kleiman-Bertini theorem, on generic transversality, under a general group action, of smooth subvarieties over an algebraically closed field of characteristic 0.
[ { "version": "v1", "created": "Tue, 1 May 2007 01:49:21 GMT" }, { "version": "v2", "created": "Tue, 12 Jun 2007 15:37:38 GMT" }, { "version": "v3", "created": "Mon, 10 Dec 2007 19:02:00 GMT" }, { "version": "v4", "created": "Thu, 20 Aug 2009 21:34:39 GMT" } ]
2009-08-21T00:00:00
[ [ "Sierra", "Susan J.", "" ] ]
0705.0056
Changhyun Ahn
Changhyun Ahn
Meta-Stable Brane Configurations with Five NS5-Branes
28 pp, 7 figures; the discussions for stability in pages 12, 15, 22, 26 added; Eight footnotes added; to appear in IJMPA
Int.J.Mod.Phys.A24:5465-5493,2009
10.1142/S0217751X09044723
null
hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
From an N=1 supersymmetric electric gauge theory with the gauge group SU(N_c) x SU(N_c') with fundamentals for each gauge group, the bifundamentals and a symmetric flavor and a conjugate symmetric flavor for SU(N_c), we apply Seiberg dual to each gauge group independently and obtain two N=1 supersymmetric dual magnetic gauge theories with dual matters including the gauge singlets. By analyzing the F-term equations of the dual magnetic superpotentials, we describe the intersecting brane configurations of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of these gauge theories. The case where the above symmetric flavor is replaced by an antisymmetric flavor is also discussed.
[ { "version": "v1", "created": "Tue, 1 May 2007 01:58:59 GMT" }, { "version": "v2", "created": "Tue, 15 May 2007 13:38:08 GMT" }, { "version": "v3", "created": "Tue, 22 Jan 2008 11:21:32 GMT" }, { "version": "v4", "created": "Sat, 14 Mar 2009 03:02:37 GMT" } ]
2009-11-30T00:00:00
[ [ "Ahn", "Changhyun", "" ] ]
0705.0057
Bryan Gaensler
B. M. Gaensler (1), L. Staveley-Smith (2), R. N. Manchester (3), M. J. Kesteven (3), L. Ball (3), A. K. Tzioumis (3) ((1) U. Sydney, (2) U. Western Australia, (3) ATNF)
Fifteen Years of High-Resolution Radio Imaging of Supernova 1987A
10 pages, including 7 b/w + 1 color embedded EPS figures; uses aipproc.cls . To appear in "Supernova 1987A: Twenty Years After: Supernovae and Gamma-Ray Bursters", edited by S. Immler, K. W. Weiler and R. McCray, American Institute of Physics, New York, 2007, in press. Updated figure 2
AIP Conf.Proc.937:86-95,2007
10.1063/1.2803627
null
astro-ph
null
Supernova 1987A in the Large Magellanic Cloud provides a spectacularly detailed view of the aftermath of a core-collapse explosion. The supernova ejecta initially coasted outward at more than 10% of the speed of light, but in 1990 were observed to decelerate rapidly as they began to encounter dense circumstellar material expelled by the progenitor star. The resulting shock has subsequently produced steadily brightening radio synchrotron emission, which is resolved by the Australia Telescope Compact Array (ATCA) into an expanding limb-brightened shell. Here we present 15 years of ATCA imaging of Supernova 1987A, at an effective angular resolution of 0.4 arcsec. We find that the radio remnant has accelerated in its expansion over this period, from approx 3600 km/s in 1992 to approx 5200 km/s at the end of 2006. The published diameters of the evolving X-ray shell have been ~15% smaller than the corresponding radio values, but a simultaneous Fourier analysis of both radio and X-ray data eliminates this discrepancy, and yields a current diameter for the shell in both wave-bands of approx 1.7 arcsec. An asymmetric brightness distribution is seen in radio images at all ATCA epochs: the eastern and western rims have higher fluxes than the northern and southern regions, indicating that most of the radio emission comes from the equatorial plane of the system, where the progenitor star's circumstellar wind is thought to be densest. The eastern lobe is brighter than and further from the supernova site than the western lobe, suggesting an additional asymmetry in the initial distribution of supernova ejecta.
[ { "version": "v1", "created": "Tue, 1 May 2007 02:04:51 GMT" }, { "version": "v2", "created": "Thu, 17 May 2007 00:13:58 GMT" } ]
2009-06-23T00:00:00
[ [ "Gaensler", "B. M.", "" ], [ "Staveley-Smith", "L.", "" ], [ "Manchester", "R. N.", "" ], [ "Kesteven", "M. J.", "" ], [ "Ball", "L.", "" ], [ "Tzioumis", "A. K.", "" ] ]
0705.0058
Wenhua Hai
Wenhua Hai, Chaohong Lee, Qianquan Zhu
Exact Floquet states of a driven condensate and their stabilities
14 pages, 3 eps figures, final version accepted for publication in J. Phys. B
null
10.1088/0953-4075/41/9/095301
null
quant-ph
null
We investigate the Gross-Pitaevskii equation for a classically chaotic system, which describes an atomic Bose-Einstein condensate confined in an optical lattice and driven by a spatiotemporal periodic laser field. It is demonstrated that the exact Floquet states appear when the external time-dependent potential is balanced by the nonlinear mean-field interaction. The balance region of parameters is divided into a phase-continuing region and a phase-jumping one. In the latter region, the Floquet states are spatiotemporal vortices of nontrivial phase structures and zero-density cores. Due to the velocity singularities of vortex cores and the blowing-up of perturbed solutions, the spatiotemporal vortices are unstable periodic states embedded in chaos. The stability and instability of these Floquet states are numerically explored by the time evolution of fidelity between the exact and numerical solutions. It is numerically illustrated that the stable Floquet states could be prepared from the uniformly initial states by slow growth of the external potential.
[ { "version": "v1", "created": "Tue, 1 May 2007 02:19:10 GMT" }, { "version": "v2", "created": "Wed, 2 Apr 2008 02:24:21 GMT" } ]
2009-11-13T00:00:00
[ [ "Hai", "Wenhua", "" ], [ "Lee", "Chaohong", "" ], [ "Zhu", "Qianquan", "" ] ]
0705.0059
Henry Tsz-King Wong
K.J. Dong, et al
Measurement of Ultra-Low Potassium Contaminations with Accelerator Mass Spectrometry
18 pages, 4 figures, 3 tables
Nucl.Instrum.Meth.A582:381-389,2007
10.1016/j.nima.2007.08.242
AS-TEXONO/07-04
nucl-ex
null
Levels of trace radiopurity in active detector materials is a subject of major concern in low-background experiments. Among the radio-isotopes, $\k40$ is one of the most abundant and yet whose signatures are difficult to reject. Procedures were devised to measure trace potassium concentrations in the inorganic salt CsI as well as in organic liquid scintillator (LS) with Accelerator Mass Spectrometry (AMS), giving, respectively, the $\k40$-contamination levels of $\sim 10^{-10}$ and $\sim 10^{-13}$ g/g. Measurement flexibilities and sensitivities are improved over conventional methods. The projected limiting sensitivities if no excess of potassium signals had been observed over background are $8 \times 10^{-13}$ g/g and $3 \times 10^{-17}$ g/g for the CsI and LS, respectively. Studies of the LS samples indicate that the radioactive contaminations come mainly in the dye solutes, while the base solvents are orders of magnitude cleaner. The work demonstrate the possibilities of measuring naturally-occurring isotopes with the AMS techniques.
[ { "version": "v1", "created": "Tue, 1 May 2007 02:25:45 GMT" } ]
2008-11-26T00:00:00
[ [ "Dong", "K. J.", "" ] ]
0705.0060
Nobuhiro Honda
Nobuhiro Honda
Double solid twistor spaces: the case of arbitrary signature
30 pages, 3 figures; v2: title changed (the original title was "Explicit construction of new Moishezon twistor spaces, II".)
null
10.1007/s00222-008-0139-5
null
math.DG math.AG
null
In a recent paper (math.DG/0701278) we constructed a series of new Moishezon twistor spaces which is a kind of variant of the famous LeBrun twistor spaces. In this paper we explicitly give projective models of another series of Moishezon twistor spaces on nCP^2 for arbitrary n>2, which can be regarded as a generalization of the twistor spaces of a 'double solid type' on 3CP^2 studied by Kreussler, Kurke, Poon and the author. Similarly to the twistor spaces of 'double solid type' on 3CP^2, projective models of present twistor spaces have a natural structure of double covering of a CP^2-bundle over CP^1. We explicitly give a defining polynomial of the branch divisor of the double covering whose restriction to fibers are degree four. If n>3 these are new twistor spaces, to the best of the author's knowledge. We also compute the dimension of the moduli space of these twistor spaces. Differently from math.DG/0701278, the present investigation is based on analysis of pluri-(half-)anticanonical systems of the twistor spaces.
[ { "version": "v1", "created": "Tue, 1 May 2007 03:54:31 GMT" }, { "version": "v2", "created": "Thu, 1 May 2008 02:29:10 GMT" } ]
2009-11-13T00:00:00
[ [ "Honda", "Nobuhiro", "" ] ]
0705.0061
Chunlei Liu
Chunlei Liu
Arithmetic progressions of primes in short intervals
null
null
null
null
math.NT
null
Green and Tao proved that the primes contains arbitrarily long arithmetic progressions. We show that, essentially the same proof leads to the following result: The primes in an short interval contains many arithmetic progressions of any given length.
[ { "version": "v1", "created": "Tue, 1 May 2007 02:41:37 GMT" } ]
2007-05-23T00:00:00
[ [ "Liu", "Chunlei", "" ] ]
0705.0062
Michael Fisher
Michael Fisher
Radiation Pressure in Lyman-alpha Forest Clouds
12 pages, 6 figures (eps)
null
null
null
astro-ph
null
The effective recombination coefficient, alpha_eff, is refined for optically thin cases. Radiation pressure in Lyman-alpha and HeII Lyman-alpha is calculated in terms of the number density and the mean free path. Pressure equilibrium between Lyman-alpha clouds and an adiabatically expanding inter-galactic medium is assumed, n_i T_i = n_c T_c. Numerical models of isothermal and adiabatic expanding Lyman-alpha forest clouds are presented, including evolving UV sources (QSOs), with various turn-on times z_on = 20, 10, and 5, and with q_0 = 1/2 in a matter-dominated Friedmann-Robertson-Walker Universe. These models lead to the conclusion that the radiation pressure and QSO turn-on time are significant in determining the range of physical size, D, and neutral hydrogen column density, N(HI), permitted for stable Lyman-alpha forest clouds. This manuscript was written in 1989 and never submitted for publication.
[ { "version": "v1", "created": "Tue, 1 May 2007 02:48:48 GMT" } ]
2007-05-23T00:00:00
[ [ "Fisher", "Michael", "" ] ]
0705.0063
Michael Fisher
Michael Fisher
The Hot Inter-Galactic Medium and the Cosmic Microwave Background
18 pages, 3 figures (eps)
null
null
null
astro-ph
null
The physical characteristics of the Lyman-alpha forest cloud systems are combined with observations on the baryonic mass density of the Universe and constraints from primordial nucleosynthesis to set boundary conditions on the Intergalactic Medium (IGM) at the epoch of z=2.5. The Universe is considered a closed system and allowed to expand adiabatically from the epoch when QSOs first ionized the IGM (5 <= z_on <= 20). The average kinetic energy of a gas is calculated in the region where the gas transitions from relativistic to non-relativistic behavior. All of the above measurements are then used to determine the thermal history of the IGM in the redshift range 2.5 <= z <= z_on. The hot IGM is assumed to inverse Compton scatter photons from the Cosmic Microwave Background (CMBR) and consequently distort the CMBR as seen at the present epoch. The temperature of the IGM at z=2.5 and the epoch z_on are adjusted, within the constraints defined above, to give the best overall agreement with published data on the temperature of the IGM. We find that the model of the IGM proposed here does not grossly distort the CMBR, and in fact agrees quite closely with the preliminary results from the Cosmic Background Explorer (COBE) satellite. However, our model of the IGM cannot explain the observed cosmic x ray background. This paper was originally written in 1990. It was never submitted for publication.
[ { "version": "v1", "created": "Tue, 1 May 2007 02:58:13 GMT" } ]
2007-05-23T00:00:00
[ [ "Fisher", "Michael", "" ] ]
0705.0064
Nicholas Parker
N. G. Parker, S. L. Cornish, C. S. Adams and A. M. Martin
Bright solitary waves and trapped solutions in Bose-Einstein condensates with attractive interactions
18 pages, 8 figures
J. Phys. B: At. Mol. Opt. Phys. 40 (2007) 3127-3142.
10.1088/0953-4075/40/15/012
null
cond-mat.other
null
We analyse the static solutions of attractive Bose-Einstein condensates under transverse confinement, both with and without axial confinement. By full numerical solution of the Gross-Pitaevskii equation and variational methods we map out the condensate solutions, their energetic properties, and their critical points for instability. With no axial confinement a bright solitary wave solution will tend to decay by dispersion unless the interaction energy is close to the critical value for collapse. In contrast, with axial confinement the only decay mechanism is collapse. The stability of a bright solitary wave solution increases with higher radial confinement. Finally we consider the stability of dynamical states containing up to four solitons and find good agreement with recent experiments.
[ { "version": "v1", "created": "Tue, 1 May 2007 03:16:51 GMT" } ]
2009-11-13T00:00:00
[ [ "Parker", "N. G.", "" ], [ "Cornish", "S. L.", "" ], [ "Adams", "C. S.", "" ], [ "Martin", "A. M.", "" ] ]
0705.0065
E. V. Gotthelf
D. J. Helfand, E. V. Gotthelf, J. P. Halpern, F. Camilo, D. R. Semler (Columbia), R. H. Becker (UC Davis), and R. L. White (STSI)
Discovery of the Putative Pulsar and Wind Nebula Associated with the TeV Gamma-ray Source HESS J1813-178
7 pages, 6 figure, Latex, emulateapj style. To appear in the Astrophysical Journal
Astrophys.J.665:1297-1303,2007
10.1086/519734
null
astro-ph
null
We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We resolve the X-ray emission from the co-located ASCA source into a point source surrounded by structured diffuse emission that fills the interior of the radio shell. The morphology of the diffuse emission strongly resembles that of a pulsar wind nebula. The spectrum of the compact source is well-characterized by a power-law with index Gamma approx 1.3, typical of young and energetic rotation-powered pulsars. For a distance of 4.5 kpc, consistent with the X-ray absorption and an association with the nearby star formation region W33, the 2-10 keV X-ray luminosities of the putative pulsar and nebula are L(PSR) = 3.2E33 ergs/s and L(PWN) = 1.4E34 ergs/s, respectively. Both the flux ratio of L(PWN)/L(PSR) = 4.3 and the total luminosity of this system predict a pulsar spin-down power of Edot > 1E37 ergs/s, placing it within the ten most energetic young pulsars in the Galaxy. A deep search for radio pulsations using the Parkes telescope sets an upper-limit of approx 0.07 mJy at 1.4 GHz for periods >~ 50 ms. We discuss the energetics of this source, and consider briefly the proximity of bright H2 regions to this and several other HESS sources, which may produce their TeV emission via inverse Compton scattering.
[ { "version": "v1", "created": "Tue, 1 May 2007 03:26:11 GMT" } ]
2009-06-23T00:00:00
[ [ "Helfand", "D. J.", "", "Columbia" ], [ "Gotthelf", "E. V.", "", "Columbia" ], [ "Halpern", "J. P.", "", "Columbia" ], [ "Camilo", "F.", "", "Columbia" ], [ "Semler", "D. R.", "", "Columbia" ], [ "Becker", "R. H.", "", "UC Davis" ], [ "White", "R. L.", "", "STSI" ] ]
0705.0066
Beth Biller
Beth A. Biller, Laird M. Close, Elena Masciadri, Eric Nielsen, Rainer Lenzen, Wolfgang Brandner, Donald McCarthy, Markus Hartung, Stephan Kellner, Eric Mamajek, Thomas Henning, Douglas Miller, Matthew Kenworthy, and Craig Kulesa
An Imaging Survey for Extrasolar Planets around 45 Close, Young Stars with SDI at the VLT and MMT
69 pages, 25 figures, accepted to ApJS, supplemental materials available at http://exoplanet.as.arizona.edu/~lclose/SDI.html
null
null
null
astro-ph
null
We present the results of a survey of 45 young (<250 Myr), close (<50 pc) stars with the Simultaneous Differential Imager (SDI) implemented at the VLT and the MMT for the direct detection of extrasolar planets. As part of the survey, we observed 54 objects total, of which 45 were close, young stars, 2 were somewhat more distant (<150 pc), very young (<10 Myr) stars, 3 were stars with known radial velocity planets, and 4 were older, very nearby (<20 pc) solar analogues. Our SDI devices use a double Wollaston prism and a quad filter to take images simultaneously at 3 wavelengths surrounding the 1.62 um methane absorption bandhead found in the spectrum of cool brown dwarfs and gas giant planets. In our VLT data, we achieved H band contrasts > 10 mag (5 sigma) at a separation of 0.5" from the primary star on 45% of our targets and H band contrasts of > 9 mag at a separation of 0.5'' on 80% of our targets. With this degree of attenuation, we should be able to image (5sigma detection) a 5 M_{Jup} planet 15 AU from a 70 Myr K1 star at 15 pc or a 5 M_{Jup} planet at 2 AU from a 12 Myr M star at 10 pc. We believe that our SDI images are the highest contrast astronomical images ever made from ground or space for methane rich companions <1'' from their star. For the best 20 of our survey stars, we attained 50% 5 sigma completeness for 6-10 M_Jup planets at semi-major axes of 20-40 AU. Thus, our completeness levels are sufficient to significantly test theoretical planet distributions. From our survey null result, we can rule out (at the 98% confidence/2.0sigma level) a model planet population using a planet distribution where N(a) $\propto$ constant out to a distance of 45 AU (further model assumptions discussed within).
[ { "version": "v1", "created": "Tue, 1 May 2007 17:18:19 GMT" } ]
2007-05-23T00:00:00
[ [ "Biller", "Beth A.", "" ], [ "Close", "Laird M.", "" ], [ "Masciadri", "Elena", "" ], [ "Nielsen", "Eric", "" ], [ "Lenzen", "Rainer", "" ], [ "Brandner", "Wolfgang", "" ], [ "McCarthy", "Donald", "" ], [ "Hartung", "Markus", "" ], [ "Kellner", "Stephan", "" ], [ "Mamajek", "Eric", "" ], [ "Henning", "Thomas", "" ], [ "Miller", "Douglas", "" ], [ "Kenworthy", "Matthew", "" ], [ "Kulesa", "Craig", "" ] ]
0705.0067
Paul S. Wesson
Bahram Mashhoon and Paul Wesson
An Embedding for General Relativity and its Implications for New Physics
null
Gen.Rel.Grav.39:1403-1412,2007
10.1007/s10714-007-0445-z
null
gr-qc
null
We show that any solution of the 4D Einstein equations of general relativity in vacuum with a cosmological constant may be embedded in a solution of the 5D Ricci-flat equations with an effective 4D cosmological "constant" that is a specific function of the extra coordinate. For unified theories of the forces in higher dimensions, this has major physical implications.
[ { "version": "v1", "created": "Tue, 1 May 2007 03:36:31 GMT" } ]
2008-11-26T00:00:00
[ [ "Mashhoon", "Bahram", "" ], [ "Wesson", "Paul", "" ] ]
0705.0068
Jinn-Ouk Gong
Jinn-Ouk Gong, Narendra Sahu
Inflation in minimal left-right symmetric model with spontaneous D-parity breaking
(v1) 4 pages, 1 figure; (v2) typos corrected; (v3) title and abstract changed, numerical estimates given, minor changes; (v4) 5 pages, relations between the neutrino masses and the CMB fluctuations become more explicit, miscellaneous changes, to appear in Physical Review D
Phys.Rev.D77:023517,2008
10.1103/PhysRevD.77.023517
null
hep-ph astro-ph hep-th
null
We present a simplest inflationary scenario in the minimal left-right symmetric model with spontaneous D-parity breaking, which is a well motivated particle physics model for neutrino masses. This leads us to connect the observed anisotropies in the cosmic microwave background to the sub-eV neutrino masses. The baryon asymmetry via the leptogenesis route is also discussed briefly.
[ { "version": "v1", "created": "Tue, 1 May 2007 04:05:57 GMT" }, { "version": "v2", "created": "Mon, 7 May 2007 07:24:24 GMT" }, { "version": "v3", "created": "Tue, 29 May 2007 09:08:21 GMT" }, { "version": "v4", "created": "Thu, 13 Dec 2007 22:26:52 GMT" } ]
2008-11-26T00:00:00
[ [ "Gong", "Jinn-Ouk", "" ], [ "Sahu", "Narendra", "" ] ]
0705.0069
Alessandro Tarozzi
Xiaohong Chen, Han Hong, Alessandro Tarozzi
Semiparametric efficiency in GMM models with auxiliary data
Published in at http://dx.doi.org/10.1214/009053607000000947 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Annals of Statistics 2008, Vol. 36, No. 2, 808-843
10.1214/009053607000000947
IMS-AOS-AOS0348
math.ST stat.TH
null
We study semiparametric efficiency bounds and efficient estimation of parameters defined through general moment restrictions with missing data. Identification relies on auxiliary data containing information about the distribution of the missing variables conditional on proxy variables that are observed in both the primary and the auxiliary database, when such distribution is common to the two data sets. The auxiliary sample can be independent of the primary sample, or can be a subset of it. For both cases, we derive bounds when the probability of missing data given the proxy variables is unknown, or known, or belongs to a correctly specified parametric family. We find that the conditional probability is not ancillary when the two samples are independent. For all cases, we discuss efficient semiparametric estimators. An estimator based on a conditional expectation projection is shown to require milder regularity conditions than one based on inverse probability weighting.
[ { "version": "v1", "created": "Tue, 1 May 2007 04:21:06 GMT" }, { "version": "v2", "created": "Fri, 4 Apr 2008 14:15:21 GMT" } ]
2008-04-04T00:00:00
[ [ "Chen", "Xiaohong", "" ], [ "Hong", "Han", "" ], [ "Tarozzi", "Alessandro", "" ] ]
0705.0070
Ana-Maria Castravet
Ana-Maria Castravet
The Cox Ring of $\bar{M}_{0,6}$
26 pages; revisions in the proof of Lemma 2.21
Trans. Amer. Math. Soc. 361 (2009), 3851--3878
null
null
math.AG math.AC
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We prove that the Cox ring of $\bar{M}_{0,6}$, the moduli space of stable, rational curves with 6 marked points, is finitely generated by sections corresponding to the boundary divisors and divisors which are pull-backs of the hyperelliptic locus in $\bar{M}_3$, the moduli space of stable, genus 3 curves, via morphisms that send a 6-pointed rational curve to a curve with 3 nodes by identifying 3 pairs of points. In particular, this gives a self-contained proof of Hassett and Tschinkel's result about the effective cone of $\bar{M}_{0,6}$ being generated by the above mentioned divisors.
[ { "version": "v1", "created": "Tue, 1 May 2007 04:34:25 GMT" }, { "version": "v2", "created": "Tue, 16 Sep 2008 04:39:38 GMT" } ]
2013-12-02T00:00:00
[ [ "Castravet", "Ana-Maria", "" ] ]
0705.0071
Daniel Alayon-Solarz
Daniel Alayon-Solarz
A note about the factorization of the angular part of the Laplacian and its application to the time-independent Schr\"odinger equation
4 pages
null
null
null
math-ph math.AP math.CV math.MP
null
Removing al least one point from the unit sphere in $ R^{3}$ allows to factorize the angular part of the laplacian with a Cauchy-Riemann type operator. Solutions to this operator define a complex algebra of potential functions. A family of these solutions is shown to be normalizable on the sphere so it is possible to construct associate solutions for every radial solution to the time-independant Schr\"odinger equation with a radial potential, such that this family of solutions is square integrable in $R^{3}$. While this family of associated solutions are singular on at least one half-plane, they are square-integrable in almost all of $R^{3}$.
[ { "version": "v1", "created": "Tue, 1 May 2007 19:13:29 GMT" }, { "version": "v2", "created": "Tue, 1 May 2007 22:46:04 GMT" }, { "version": "v3", "created": "Fri, 4 May 2007 02:54:25 GMT" } ]
2007-05-23T00:00:00
[ [ "Alayon-Solarz", "Daniel", "" ] ]
0705.0072
Teiji Kunihiro
Teiji Kunihiro
Low Mass Scalar Mesons and Related Topics
talk presented at Yukawa International Seminar(YKIS) 2006 "New Frontiers in QCD -- Exotic Hadrons and Hadronic Matter --", November 20 to December 8, 2006, at Yukawa Institute for Theoretical Physics, Kyoto University. 4 pages.tobe published in the proceedings(Supplemet of Prog. Theor. Phys.)
Prog.Theor.Phys.Suppl.168:156-159,2007
10.1143/PTPS.168.156
null
hep-ph
null
We give a brief survey on the physical significance of the low-mass scalar mesons in QCD, and also report on recent lattice studies on the sigma and kappa mesons. The importance to explore the in-medium properties of the hadrons is mentioned.
[ { "version": "v1", "created": "Tue, 1 May 2007 05:28:04 GMT" } ]
2008-11-26T00:00:00
[ [ "Kunihiro", "Teiji", "" ] ]
0705.0073
Itzhak Fouxon
Itzhak Fouxon and P\'eter Horvai
Fluctuation relation and pairing rule for Lyapunov exponents of inertial particles in turbulence
6 pages
null
10.1088/1742-5468/2007/08/L08002
null
nlin.CD
null
We study the motion of small particles in a random turbulent flow assuming linear law of friction. We derive a symmetry relation obeyed by the large deviations of the finite time Lyapunov exponents in the phase space. The relation applies when either the statistics of the strain matrix is invariant under the transposition or when it is time-reversible. We show that, as a result, the Lyapunov exponents come in pairs which sum is equal to minus the inverse relaxation time of the particles. We use the pairing to consider the Kaplan-Yorke dimension of the particles attractor in the phase space. In particular, the results apply to case of the flow which is white noise in time.
[ { "version": "v1", "created": "Tue, 1 May 2007 05:39:35 GMT" } ]
2009-11-13T00:00:00
[ [ "Fouxon", "Itzhak", "" ], [ "Horvai", "Péter", "" ] ]
0705.0074
Utpal Sarkar
Ernest Ma and Utpal Sarkar
Revelations of the E_6/U(1)_N Model: Two-Loop Neutrino Mass and Dark Matter
10 pages, 3 figures
Phys.Lett.B653:288-291,2007
10.1016/j.physletb.2007.08.019
UCRHEP-T430
hep-ph
null
The E_6/U(1)_N gauge extension of the Supersymmetric Standard Model, first proposed by Ma, is shown to have exactly the requisite ingredients to realize the important new idea that dark matter is the origin of neutrino mass. With the implementation of a discrete Z_2 X Z_2 symmetry, and particle content given by three {27} representations of E_6, neutrino masses are naturally generated in two loops, with candidates of dark matter in the loops. All particles of this model are expected to be at or below the TeV scale, allowing them to be observable at the LHC.
[ { "version": "v1", "created": "Tue, 1 May 2007 05:58:27 GMT" } ]
2008-11-26T00:00:00
[ [ "Ma", "Ernest", "" ], [ "Sarkar", "Utpal", "" ] ]
0705.0075
Markus Henrich J.
M. J. Henrich, M. Michel and G. Mahler
Driven Spin Systems as Quantum Thermodynamic Machines: Fundamental Limits
9 pages, 11 figures, accepted for publication in Phys. Rev. E
null
10.1103/PhysRevE.75.051118
null
cond-mat.stat-mech
null
We show that coupled two level systems like qubits studied in quantum information can be used as a thermodynamic machine. At least three qubits or spins are necessary and arranged in a chain. The system is interfaced between two split baths and the working spin in the middle is externally driven. The machine performs Carnot-type cycles and is able to work as heat pump or engine depending on the temperature difference of the baths $\Delta T$ and the energy differences in the spin system $\Delta E$. It can be shown that the efficiency is a function of $\Delta T$ and $\Delta E$.
[ { "version": "v1", "created": "Tue, 1 May 2007 06:22:20 GMT" } ]
2009-11-13T00:00:00
[ [ "Henrich", "M. J.", "" ], [ "Michel", "M.", "" ], [ "Mahler", "G.", "" ] ]
0705.0076
Gab Jin Oh
Cheoljun Eom, Gabjin Oh, Seunghwan Kim
Deterministic Factors of Stock Networks based on Cross-correlation in Financial Market
4 pages, 1 figure
null
10.1016/j.physa.2007.04.102
null
q-fin.ST physics.data-an
null
The stock market has been known to form homogeneous stock groups with a higher correlation among different stocks according to common economic factors that influence individual stocks. We investigate the role of common economic factors in the market in the formation of stock networks, using the arbitrage pricing model reflecting essential properties of common economic factors. We find that the degree of consistency between real and model stock networks increases as additional common economic factors are incorporated into our model. Furthermore, we find that individual stocks with a large number of links to other stocks in a network are more highly correlated with common economic factors than those with a small number of links. This suggests that common economic factors in the stock market can be understood in terms of deterministic factors.
[ { "version": "v1", "created": "Tue, 1 May 2007 06:24:24 GMT" } ]
2009-11-13T00:00:00
[ [ "Eom", "Cheoljun", "" ], [ "Oh", "Gabjin", "" ], [ "Kim", "Seunghwan", "" ] ]
0705.0077
Sanjeev Naguleswaran
Ian Fuss, Lang White, Peter Sherman and Sanjeev Naguleswaran
An analytic solution for one-dimensional quantum walks
23 pages
null
null
null
quant-ph
null
The first general analytic solutions for the one-dimensional walk in position and momentum space are derived. These solutions reveal, among other things, new symmetry features of quantum walk probability densities and further insight into the behaviour of their moments. The analytic expressions for the quantum walk probability distributions provide a means of modelling quantum phenomena that is analogous to that provided by random walks in the classical domain.
[ { "version": "v1", "created": "Tue, 1 May 2007 06:33:11 GMT" } ]
2007-05-23T00:00:00
[ [ "Fuss", "Ian", "" ], [ "White", "Lang", "" ], [ "Sherman", "Peter", "" ], [ "Naguleswaran", "Sanjeev", "" ] ]
0705.0078
Claudius Gros
Claudius Gros
Neural networks with transient state dynamics
null
New J.Phys.9:109,2007
10.1088/1367-2630/9/4/109
null
cond-mat.dis-nn astro-ph cond-mat.other nlin.AO q-bio.NC
null
We investigate dynamical systems characterized by a time series of distinct semi-stable activity patterns, as they are observed in cortical neural activity patterns. We propose and discuss a general mechanism allowing for an adiabatic continuation between attractor networks and a specific adjoined transient-state network, which is strictly dissipative. Dynamical systems with transient states retain functionality when their working point is autoregulated; avoiding prolonged periods of stasis or drifting into a regime of rapid fluctuations. We show, within a continuous-time neural network model, that a single local updating rule for online learning allows simultaneously (i) for information storage via unsupervised Hebbian-type learning, (ii) for adaptive regulation of the working point and (iii) for the suppression of runaway synaptic growth. Simulation results are presented; the spontaneous breaking of time-reversal symmetry and link symmetry are discussed.
[ { "version": "v1", "created": "Tue, 1 May 2007 06:27:50 GMT" } ]
2010-02-11T00:00:00
[ [ "Gros", "Claudius", "" ] ]
0705.0079
Kazunori Nakayama
Masahiro Kawasaki, Kazunori Nakayama
Baryon Asymmetry in a Heavy Moduli Scenario
36 pages, 5 figures; added a reference; v3: minor corrections
Phys.Rev.D76:043502,2007
10.1103/PhysRevD.76.043502
null
hep-ph
null
In some models of supersymmetry breaking, modulus fields are heavy enough to decay before BBN. But the large entropy produced via moduli decay significantly dilutes the preexisting baryon asymmetry of the universe. We study whether Affleck-Dine mechanism can provide enough baryon asymmetry which survives the dilution, and find several situations in which desirable amount of baryon number remains after the dilution. The possibility of non-thermal dark matter is also discussed. This provides the realistic cosmological scenario with heavy moduli.
[ { "version": "v1", "created": "Tue, 1 May 2007 06:45:50 GMT" }, { "version": "v2", "created": "Wed, 9 May 2007 05:02:45 GMT" }, { "version": "v3", "created": "Sun, 5 Aug 2007 08:33:27 GMT" } ]
2008-11-26T00:00:00
[ [ "Kawasaki", "Masahiro", "" ], [ "Nakayama", "Kazunori", "" ] ]
0705.0080
Michael Ibison
M. Ibison
Cosmological test of the Yilmaz theory of gravity
null
Class.Quant.Grav.23:577-589,2006
10.1088/0264-9381/23/3/001
null
gr-qc
null
We test the Yilmaz theory of gravitation by working out the corresponding Friedmann-type equations generated by assuming the Friedmann-Robertson-Walker cosmological metrics. In the case that space is flat the theory is consistent only with either a completely empty universe or a negative energy vacuum that decays to produce a constant density of matter. In both cases the total energy remains zero at all times, and in the latter case the acceleration of the expansion is always negative. To obtain a more flexible and potentially more realistic cosmology, the equation of state relating the pressure and energy density of the matter creation process must be different from the vacuum, as for example is the case in the steady-state models of Gold, Bondi, Hoyle and others. The theory does not support the cosmological principle for curved space K =/= 0 cosmological metrics.
[ { "version": "v1", "created": "Tue, 1 May 2007 06:50:20 GMT" } ]
2009-11-13T00:00:00
[ [ "Ibison", "M.", "" ] ]
0705.0081
Yeow Meng Chee
Yeow Meng Chee, San Ling
Constructions of q-Ary Constant-Weight Codes
12 pages
IEEE Transactions on Information Theory, Vol. 53, No. 1, January 2007, pp. 135-146
10.1109/TIT.2006.887499
null
cs.IT math.IT
null
This paper introduces a new combinatorial construction for q-ary constant-weight codes which yields several families of optimal codes and asymptotically optimal codes. The construction reveals intimate connection between q-ary constant-weight codes and sets of pairwise disjoint combinatorial designs of various types.
[ { "version": "v1", "created": "Tue, 1 May 2007 07:16:43 GMT" } ]
2007-07-13T00:00:00
[ [ "Chee", "Yeow Meng", "" ], [ "Ling", "San", "" ] ]
0705.0082
Marco Bochicchio
Marco Bochicchio
Exact beta function from the holographic loop equation of large-N QCD_4
42 pages, latex. The exponent of the Vandermonde determinant in the quantum effective action has been changed, because it has been employed a holomorphic rather than a hermitean resolution of identity in the functional integral. Beta function unchanged. New explanations and references added, typos corrected
JHEP 0709:033,2007
10.1088/1126-6708/2007/09/033
null
hep-th
null
We construct and study a previously defined quantum holographic effective action whose critical equation implies the holographic loop equation of large-N QCD_4 for planar self-avoiding loops in a certain regularization scheme. We extract from the effective action the exact beta function in the given scheme. For the Wilsonean coupling constant the beta function is exacly one loop and the first coefficient agrees with its value in perturbation theory. For the canonical coupling constant the exact beta function has a NSVZ form and the first two coefficients agree with their value in perturbation theory.
[ { "version": "v1", "created": "Tue, 1 May 2007 07:21:15 GMT" }, { "version": "v2", "created": "Fri, 8 Jun 2007 01:30:11 GMT" } ]
2009-04-22T00:00:00
[ [ "Bochicchio", "Marco", "" ] ]
0705.0083
Michael Ibison
M. Ibison
Are Advanced Potentials Anomalous?
null
AAAS Conference Proceedings on Reverse Causation, pp. 3-19 (2006)
null
null
physics.gen-ph physics.class-ph
null
Advanced electromagnetic potentials are indigenous to the classical Maxwell theory. Generally however they are deemed undesirable and are forcibly excluded, destroying the theory's inherent time-symmetry. We investigate the reason for this, pointing out that it is not necessary and in some cases is counter-productive. We then focus on the direct-action theory in which the advanced and retarded contributions are present symmetrically, with no opportunity to supplement the particular integral solution of the wave equation with an arbitrary complementary function. One then requires a plausible explanation for the observed broken symmetry that, commonly, is understood cannot be met by the Wheeler-Feynman mechanism because the necessary boundary condition cannot be satisfied in acceptable cosmologies. We take this opportunity to argue that the boundary condition is already met by all expanding cosmologies simply as a result of cosmological red-shift. A consequence is that the cosmological and thermodynamic arrows of time can be equated, the direct action version of EM is preferred, and that advanced potentials are ubiquitous.
[ { "version": "v1", "created": "Tue, 1 May 2007 07:23:10 GMT" } ]
2007-05-23T00:00:00
[ [ "Ibison", "M.", "" ] ]
0705.0084
Hyosun Kim
Hyosun Kim (1) and Woong-Tae Kim (1) ((1) Department of Physics and Astronomy, FPRD, Seoul National University, Seoul, Korea)
Dynamical Friction of a Circular-Orbit Perturber in a Gaseous Medium
28 pages, 9 figures, accepted for publication in Astrophysical Journal
Astrophys.J.665:432-444,2007
10.1086/519302
null
astro-ph
null
We investigate the gravitational wake due to, and dynamical friction on, a perturber moving on a circular orbit in a uniform gaseous medium using a semi-analytic method. This work is a straightforward extension of Ostriker (1999) who studied the case of a straight-line trajectory. The circular orbit causes the bending of the wake in the background medium along the orbit, forming a long trailing tail. The wake distribution is thus asymmetric, giving rise to the drag forces in both opposite (azimuthal) and lateral (radial) directions to the motion of the perturber, although the latter does not contribute to orbital decay much. For subsonic motion, the density wake with a weak tail is simply a curved version of that in Ostriker and does not exhibit the front-back symmetry. The resulting drag force in the opposite direction is remarkably similar to the finite-time, linear-trajectory counterpart. On the other hand, a supersonic perturber is able to overtake its own wake, possibly multiple times, and develops a very pronounced tail. The supersonic tail surrounds the perturber in a trailing spiral fashion, enhancing the perturbed density at the back as well as far front of the perturber. We provide the fitting formulae for the drag forces as functions of the Mach number, whose azimuthal part is surprisingly in good agreement with the Ostriker's formula, provided Vp t=2 Rp, where Vp and Rp are the velocity and orbital radius of the perturber, respectively.
[ { "version": "v1", "created": "Tue, 1 May 2007 07:34:49 GMT" } ]
2009-06-23T00:00:00
[ [ "Kim", "Hyosun", "" ], [ "Kim", "Woong-Tae", "" ] ]
0705.0085
{\O}yvind Ytrehus
Angela I. Barbero Diez and Oyvind Ytrehus
An efficient centralized binary multicast network coding algorithm for any cyclic network
null
null
null
null
cs.IT math.IT
null
We give an algorithm for finding network encoding and decoding equations for error-free multicasting networks with multiple sources and sinks. The algorithm given is efficient (polynomial complexity) and works on any kind of network (acyclic, link cyclic, flow cyclic, or even in the presence of knots). The key idea will be the appropriate use of the delay (both natural and additional) during the encoding. The resulting code will always work with finite delay with binary encoding coefficients.
[ { "version": "v1", "created": "Tue, 1 May 2007 08:03:18 GMT" } ]
2007-07-13T00:00:00
[ [ "Diez", "Angela I. Barbero", "" ], [ "Ytrehus", "Oyvind", "" ] ]
0705.0086
Maurice Margenstern
Maurice Margenstern
About the domino problem in the hyperbolic plane, a new solution: complement
20 pages
M. Margenstern, "The domino problem of the hyperbolic plane is undecidable", Theoretical Computer Science, vol. 407, (2008), 29-84
10.1016/j.tcs.2008.04.038
null
cs.CG cs.DM
null
In this paper, we complete the construction of paper arXiv:cs.CG/0701096v2. Together with the proof contained in arXiv:cs.CG/0701096v2, this paper definitely proves that the general problem of tiling the hyperbolic plane with {\it \`a la} Wang tiles is undecidable.
[ { "version": "v1", "created": "Tue, 1 May 2007 09:29:59 GMT" }, { "version": "v2", "created": "Tue, 1 May 2007 20:09:36 GMT" }, { "version": "v3", "created": "Wed, 9 May 2007 06:25:50 GMT" }, { "version": "v4", "created": "Fri, 18 May 2007 15:14:52 GMT" } ]
2009-07-06T00:00:00
[ [ "Margenstern", "Maurice", "" ] ]
0705.0087
Jae Dong Noh
Jae Dong Noh
Percolation transition in networks with degree-degree correlation
7 pages, 11 figure
Phys. Rev. E 76, 026116 (2007).
10.1103/PhysRevE.76.026116
null
cond-mat.stat-mech
null
We introduce an exponential random graph model for networks with a fixed degree distribution and with a tunable degree-degree correlation. We then investigate the nature of a percolation transition in the correlated network with the Poisson degree distribution. It is found that negative correlation is irrelevant in that the percolation transition in the disassortative network belongs to the same universality class of the uncorrelated network. Positive correlation turns out to be relevant. The percolation transition in the assortative network is characterized by the non-diverging mean size of finite clusters and power-law scalings of the density of the largest cluster and the cluster size distribution in the non-percolating phase as well as at the critical point. Our results suggest that the unusual type percolation transition in the growing network models reported recently may be inherited from the assortative degree-degree correlation.
[ { "version": "v1", "created": "Tue, 1 May 2007 08:46:21 GMT" } ]
2007-08-30T00:00:00
[ [ "Noh", "Jae Dong", "" ] ]
0705.0088
Jae Choon Cha
Jae Choon Cha
Link concordance, homology cobordism, and Hirzebruch-type defects from iterated p-covers
48 pages; title changed, some typos fixed, Lemma 5.10 revised; to appear in the Journal of the European Mathematical Society
null
null
null
math.GT
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We obtain new invariants of topological link concordance and homology cobordism of 3-manifolds from Hirzebruch-type intersection form defects of towers of iterated p-covers. Our invariants can extract geometric information from an arbitrary depth of the derived series of the fundamental group, and can detect torsion which is invisible via signature invariants. Applications illustrating these features include the following: (1) There are infinitely many homology equivalent rational 3-spheres which are indistinguishable via multisignatures, eta-invariants, and L2-signatures but have distinct homology cobordism types. (2) There is an infinite family of 2-torsion (amphichiral) knots, including the figure eight knot, with non-slice iterated Bing doubles; as a special case, we give the first proof of the conjecture that the Bing double of the figure eight knot is not slice. (3) There exist infinitely many torsion elements at any depth of the Cochran-Orr-Teichner filtration of link concordance.
[ { "version": "v1", "created": "Tue, 1 May 2007 17:10:42 GMT" }, { "version": "v2", "created": "Fri, 11 May 2007 06:24:04 GMT" }, { "version": "v3", "created": "Mon, 16 Jun 2008 07:56:05 GMT" } ]
2008-06-16T00:00:00
[ [ "Cha", "Jae Choon", "" ] ]
0705.0089
Adilson Enio Motter
Adilson E. Motter
Bounding network spectra for network design
17 pages, 4 figures
New J. Phys. 9, 182 (2007)
10.1088/1367-2630/9/6/182
null
cond-mat.dis-nn nlin.AO nlin.CD
null
The identification of the limiting factors in the dynamical behavior of complex systems is an important interdisciplinary problem which often can be traced to the spectral properties of an underlying network. By deriving a general relation between the eigenvalues of weighted and unweighted networks, here I show that for a wide class of networks the dynamical behavior is tightly bounded by few network parameters. This result provides rigorous conditions for the design of networks with predefined dynamical properties and for the structural control of physical processes in complex systems. The results are illustrated using synchronization phenomena as a model process.
[ { "version": "v1", "created": "Tue, 1 May 2007 09:04:08 GMT" } ]
2007-07-03T00:00:00
[ [ "Motter", "Adilson E.", "" ] ]
0705.0090
Yuichi Yamada
Yuichi Yamada
Lens space surgeries on A'Campo's divide knots
26 pages, 19 figures. The proofs of Theorem 1.3 and Lemma 3.5 are written down by braid calculus. Section 4 (on the operation Adding squares) is revised and improved the most. Section 5 is added
Algebr. Geom. Topol. 9 (2009) 397-428
10.2140/agt.2009.9.397
null
math.GT
null
It is proved that every knot in the major subfamilies of J. Berge's lens space surgery (i.e., knots yielding a lens space by Dehn surgery) is presented by an L-shaped (real) plane curve as a "divide knot" defined by N. A'Campo in the context of singularity theory of complex curves. For each knot given by Berge's parameters, the corresponding plane curve is constructed. The surgery coefficients are also considered. Such presentations support us to study each knot itself, and the relationship among the knots in the set of lens space surgeries.
[ { "version": "v1", "created": "Tue, 1 May 2007 09:06:27 GMT" }, { "version": "v2", "created": "Fri, 9 May 2008 06:51:06 GMT" } ]
2016-01-20T00:00:00
[ [ "Yamada", "Yuichi", "" ] ]
0705.0091
David Abergel
D. S. L. Abergel, A. Russell and Vladimir I. Fal'ko
Visibility of graphene flakes on a dielectric substrate
pdflatex, 3 pages, 3 figures
Applied Physics Letters 91, 063125 (2007)
10.1063/1.2768625
null
cond-mat.mes-hall
null
We model the optical visibility of monolayer and bilayer graphene deposited on a silicon/silicon oxide substrate or thermally annealed on the surface of silicon carbide. We consider reflection and transmission setups, and find that visibility is strongest in reflection reaching the optimum conditions when the bare substrate transmits light resonantly. In the optical range of frequencies a bilayer is approximately twice as visible as a monolayer thereby making the two types of graphene distinguishable from each other.
[ { "version": "v1", "created": "Tue, 1 May 2007 09:27:46 GMT" }, { "version": "v2", "created": "Mon, 25 Feb 2008 19:02:23 GMT" } ]
2008-02-25T00:00:00
[ [ "Abergel", "D. S. L.", "" ], [ "Russell", "A.", "" ], [ "Fal'ko", "Vladimir I.", "" ] ]
0705.0092
Vicente Garzo
Vicente Garzo
Shear-rate dependent transport coefficients for inelastic Maxwell models
26 pages, 9 figures
J. Phys. A: Math. Theor. 40, 10729 (2007)
10.1088/1751-8113/40/35/002
null
cond-mat.stat-mech cond-mat.soft
null
The Boltzmann equation for d-dimensional inelastic Maxwell models is considered to analyze transport properties in spatially inhomogeneous states close to the simple shear flow. A normal solution is obtained via a Chapman--Enskog--like expansion around a local shear flow distribution f^{(0)} that retains all the hydrodynamic orders in the shear rate. The constitutive equations for the heat and momentum fluxes are obtained to first order in the deviations of the hydrodynamic field gradients from their values in the reference state and the corresponding generalized transport coefficients are {\em exactly} determined in terms of the coefficient of restitution \alpha and the shear rate a. Since f^{(0)} applies for arbitrary values of the shear rate and is not restricted to weak dissipation, the transport coefficients turn out to be nonlinear functions of both parameters a and \alpha. A comparison with previous results obtained for inelastic hard spheres from a kinetic model of the Boltzmann equation is also carried out.
[ { "version": "v1", "created": "Tue, 1 May 2007 11:26:30 GMT" }, { "version": "v2", "created": "Fri, 13 Jul 2007 14:55:30 GMT" } ]
2009-11-13T00:00:00
[ [ "Garzo", "Vicente", "" ] ]
0705.0093
Nikita Buznikov
N.A. Buznikov, C.O. Kim
Modeling of torsion stress giant magnetoimpedance in amorphous wires with negative magnetostriction
17 pages, 5 figures
J. Magn. Magn. Mater. 315 (2007) 89
10.1016/j.jmmm.2007.03.186
null
cond-mat.mtrl-sci
null
A model describing the influence of torsion stress on the giant magnetoimpedance in amorphous wires with negative magnetostriction is proposed. The wire impedance is found by means of the solution of Maxwell equations together with the Landau-Lifshitz equation, assuming a simplified spatial distribution of the magnetoelastic anisotropy induced by the torsion stress. The impedance is analyzed as a function of the external magnetic field, torsion stress and frequency. It is shown that the magnetoimpedance ratio torsion dependence has an asymmetric shape, with a sharp peak at some value of the torsion stress. The calculated field and stress dependences of the impedance are in qualitative agreement with results of the experimental study of the torsion stress giant magnetoimpedance in Co-based amorphous wires.
[ { "version": "v1", "created": "Tue, 1 May 2007 11:09:55 GMT" } ]
2007-05-23T00:00:00
[ [ "Buznikov", "N. A.", "" ], [ "Kim", "C. O.", "" ] ]
0705.0094
Wim de Boer
W. de Boer, A. Nordt, C. Sander, V. Zhukov (University of Karlsruhe, Germany)
A new Determination of the Extragalactic Background of Diffuse Gamma Rays taking into account Dark Matter Annihilation
7 pages, 4 figures. Accepted by A&A, made Fig. 4 and table 1 consistent
Astron.Astrophys.470:61-66,2007
10.1051/0004-6361:20054613
null
astro-ph
null
The extragalactic background (EGB) of diffuse gamma rays can be determined by subtracting the Galactic contribution from the data. This requires a Galactic model (GM) and we include for the first time the contribution of dark matter annihilation (DMA), which was previously proposed as an explanation for the EGRET excess of diffuse Galactic gamma rays above 1 GeV. In this paper it is shown that the newly determined EGB shows a characteristic high energy bump on top of a steeply falling soft contribution. The bump is shown to be compatible with a contribution from an extragalactic DMA signal from weakly interacting massive particles (WIMPs) with a mass between 50 and 100 GeV in agreement with the EGRET excess of the Galactic diffuse gamma rays and in disagreement with earlier analysis. The remaining soft contribution of the EGB is shown to resemble the spectra of the observed point sources in our Galaxy.
[ { "version": "v1", "created": "Tue, 1 May 2007 19:44:51 GMT" }, { "version": "v2", "created": "Fri, 11 May 2007 10:37:00 GMT" } ]
2009-11-13T00:00:00
[ [ "de Boer", "W.", "", "University of Karlsruhe,\n Germany" ], [ "Nordt", "A.", "", "University of Karlsruhe,\n Germany" ], [ "Sander", "C.", "", "University of Karlsruhe,\n Germany" ], [ "Zhukov", "V.", "", "University of Karlsruhe,\n Germany" ] ]
0705.0095
A. V. Ustinov
J. Lisenfeld, A. Lukashenko, M. Ansmann, J. M. Martinis, and A. V. Ustinov
Temperature dependence of coherent oscillations in Josephson phase qubits
4 pages, 4 figures
null
10.1103/PhysRevLett.99.170504
null
cond-mat.supr-con
null
We experimentally investigate the temperature dependence of Rabi oscillations and Ramsey fringes in superconducting phase qubits driven by microwave pulses. In a wide range of temperatures, we find that both the decay time and the amplitude of these coherent oscillations remain nearly unaffected by thermal fluctuations. The oscillations are observed well above the crossover temperature from thermally activated escape to quantum tunneling for undriven qubits. In the two-level limit, coherent qubit response rapidly vanishes as soon as the energy of thermal fluctuations kT becomes larger than the energy level spacing of the qubit. Our observations shed new light on the origin of decoherence in superconducting qubits. The experimental data suggest that, without degrading already achieved coherence times, phase qubits can be operated at temperatures much higher than those reported till now.
[ { "version": "v1", "created": "Tue, 1 May 2007 11:35:05 GMT" } ]
2009-11-13T00:00:00
[ [ "Lisenfeld", "J.", "" ], [ "Lukashenko", "A.", "" ], [ "Ansmann", "M.", "" ], [ "Martinis", "J. M.", "" ], [ "Ustinov", "A. V.", "" ] ]
0705.0096
David Orozco Su\'arez
D. Orozco Suarez, L.R. Bellot Rubio and J.C. del Toro Iniesta
Quiet Sun magnetic fields from space-borne observations: simulating Hinode's case
Accepted for publication in ApJ Letters
null
10.1086/519279
null
astro-ph
null
We examine whether or not it is possible to derive the field strength distribution of quiet Sun internetwork regions from very high spatial resolution polarimetric observations in the visible. In particular, we consider the case of the spectropolarimeter attached to the Solar Optical Telescope aboard Hinode. Radiative magneto-convection simulations are used to synthesize the four Stokes profiles of the \ion{Fe}{1} 630.2 nm lines. Once the profiles are degraded to a spatial resolution of 0\farcs32 and added noise, we infer the atmospheric parameters by means of Milne-Eddington inversions. The comparison of the derived values with the real ones indicates that the visible lines yield correct internetwork field strengths and magnetic fluxes, with uncertainties smaller than $\sim$150 G, when a stray light contamination factor is included in the inversion. Contrary to the results of ground-based observations at 1\arcsec, weak fields are retrieved wherever the field is weak in the simulation.
[ { "version": "v1", "created": "Tue, 1 May 2007 11:51:30 GMT" } ]
2009-11-13T00:00:00
[ [ "Suarez", "D. Orozco", "" ], [ "Rubio", "L. R. Bellot", "" ], [ "Iniesta", "J. C. del Toro", "" ] ]
0705.0097
Gianmaria Falco
G.M. Falco, A. Pelster, R. Graham
Collective Oscillations in Trapped Bose-Einstein Condensed Gases in the Presence of Weak Disorder
6 pages, 2 figures
Phys. Rev. A 76, 013624 (2007)
10.1103/PhysRevA.76.013624
null
cond-mat.other cond-mat.stat-mech
null
The influence of a weak random potential on the collective modes of a trapped interacting Bose-Einstein condensate at zero temperature is calculated in the limit when the correlation length of the disorder is smaller than the healing length of the superfluid. The problem is solved in the Thomas-Fermi limit by generalizing the superfluid hydrodynamic equations to allow for the presence of weak disorder. We find that the disorder-induced frequency-shifts of the low-energy excitations can be of the same order of magnitude as the beyond mean-field corrections in the normal interaction recently observed experimentally.
[ { "version": "v1", "created": "Tue, 1 May 2007 11:46:07 GMT" } ]
2010-02-05T00:00:00
[ [ "Falco", "G. M.", "" ], [ "Pelster", "A.", "" ], [ "Graham", "R.", "" ] ]