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0705.3598
Luisa Beghin
Luisa Beghin
Pseudoprocesses governed by higher-order fractional differential equations
Submitted for publication (March 2007)
Electronic Journal of Probability, Vol.15 (2010), n.22, 684-709
null
null
math.PR
null
We study here a heat-type differential equation of order n greater than two, in the case where the time-derivative is supposed to be fractional. The corresponding solution can be described as the transition function of a pseudoprocess (coinciding with the one governed by the standard, non-fractional, equation) with a time argument T which is itself random. The distribution of T is presented together with some features of the solution (such as analytic expressions for its moments).
[ { "version": "v1", "created": "Thu, 24 May 2007 14:55:28 GMT" } ]
2011-03-03T00:00:00
[ [ "Beghin", "Luisa", "" ] ]
0705.3599
Christopher Smyth
James McKee and Chris Smyth
Integer symmetric matrices having all their eigenvalues in the interval [-2,2]
33 pages, 18 figures
null
null
null
math.CO math.NT
null
We completely describe all integer symmetric matrices that have all their eigenvalues in the interval [-2,2]. Along the way we classify all signed graphs, and then all charged signed graphs, having all their eigenvalues in this same interval. We then classify subsets of the above for which the integer symmetric matrices, signed graphs and charged signed graphs have all their eigenvalues in the open interval (-2,2).
[ { "version": "v1", "created": "Thu, 24 May 2007 15:45:39 GMT" } ]
2007-05-25T00:00:00
[ [ "McKee", "James", "" ], [ "Smyth", "Chris", "" ] ]
0705.3600
Bertrand Eynard
Bertrand Eynard (SPhT), Nicolas Orantin (SPhT)
Weil-Petersson volume of moduli spaces, Mirzakhani's recursion and matrix models
Latex, 9 pages
null
null
SPhT-T07/065
math-ph hep-th math.AG math.MP
null
We show that Mirzakhani's recursions for the volumes of moduli space of Riemann surfaces are a special case of random matrix loop equations, and therefore we confirm again that Kontsevitch's integral is a generating function for those volumes. As an application, we propose a formula for the Weil-Petersson volume Vol(M_{g,0}).
[ { "version": "v1", "created": "Thu, 24 May 2007 15:10:52 GMT" } ]
2007-06-13T00:00:00
[ [ "Eynard", "Bertrand", "", "SPhT" ], [ "Orantin", "Nicolas", "", "SPhT" ] ]
0705.3601
Peter Henselder
S. Odendahl and P. Henselder
Spin Description in the Star Product and the Path Integral Formalism
14 pages
null
10.1016/j.physleta.2007.10.035
null
quant-ph
null
The spin can be described in the star product formalism by extending the bosonic Moyal product in the fermionic sector. The fermionic star product is then the Clifford product of geometric algebra and it is possible to formulate the fermionic star product formalism in analogy to the bosonic star product formalism. For the fermionic star product description of spin, one can then establish the relation to other approaches that describe spin with fermionic variables, i.e. the operator formalism and the path integral formalism. It is shown that the fermionic star product formalism and the fermionic path integral formalism are related in analogy to their bosonic counterparts.
[ { "version": "v1", "created": "Thu, 24 May 2007 15:18:44 GMT" } ]
2009-11-13T00:00:00
[ [ "Odendahl", "S.", "" ], [ "Henselder", "P.", "" ] ]
0705.3602
Benedicte Haas
B\'en\'edicte Haas, Jim Pitman, Matthias Winkel
Spinal partitions and invariance under re-rooting of continuum random trees
Published in at http://dx.doi.org/10.1214/08-AOP434 the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Annals of Probability 2009, Vol. 37, No. 4, 1381-1411
10.1214/08-AOP434
IMS-AOP-AOP434
math.PR
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We develop some theory of spinal decompositions of discrete and continuous fragmentation trees. Specifically, we consider a coarse and a fine spinal integer partition derived from spinal tree decompositions. We prove that for a two-parameter Poisson--Dirichlet family of continuous fragmentation trees, including the stable trees of Duquesne and Le Gall, the fine partition is obtained from the coarse one by shattering each of its parts independently, according to the same law. As a second application of spinal decompositions, we prove that among the continuous fragmentation trees, stable trees are the only ones whose distribution is invariant under uniform re-rooting.
[ { "version": "v1", "created": "Thu, 24 May 2007 15:23:59 GMT" }, { "version": "v2", "created": "Thu, 27 Aug 2009 14:06:26 GMT" } ]
2009-08-27T00:00:00
[ [ "Haas", "Bénédicte", "" ], [ "Pitman", "Jim", "" ], [ "Winkel", "Matthias", "" ] ]
0705.3603
Cesare Tronci
John Gibbons, Darryl D Holm, Cesare Tronci
Vlasov moments, integrable systems and singular solutions
16 pages, no figures. Submitted to Phys. Lett. A
null
10.1016/j.physleta.2007.08.054
null
nlin.SI math-ph math.MP physics.acc-ph physics.plasm-ph
null
The Vlasov equation for the collisionless evolution of the single-particle probability distribution function (PDF) is a well-known Lie-Poisson Hamiltonian system. Remarkably, the operation of taking the moments of the Vlasov PDF preserves the Lie-Poisson structure. The individual particle motions correspond to singular solutions of the Vlasov equation. The paper focuses on singular solutions of the problem of geodesic motion of the Vlasov moments. These singular solutions recover geodesic motion of the individual particles.
[ { "version": "v1", "created": "Thu, 24 May 2007 15:36:48 GMT" } ]
2008-04-25T00:00:00
[ [ "Gibbons", "John", "" ], [ "Holm", "Darryl D", "" ], [ "Tronci", "Cesare", "" ] ]
0705.3604
Nuno Luzia
Nuno Luzia
Measure of full dimension for some nonconformal repellers
11 pages
null
null
null
math.DS
null
We prove the existence of an ergodic measure with full Hausdorff dimension for a class of nonlinear nonconformal skew-product transformations. In order to do so we establish a variational principle for the topological pressure of certain noncompact sets.
[ { "version": "v1", "created": "Thu, 24 May 2007 15:43:57 GMT" } ]
2007-05-25T00:00:00
[ [ "Luzia", "Nuno", "" ] ]
0705.3605
Anatoly Vershik
A.Vershik, S.Kerov
Four Drafts of The Representation Theory of the Group of Infinite Matrices over Finite Fields
26 pp. Ref.21
null
null
null
math.RT math.QA
null
Preface (A.Vershik) - about these texts (3.); I.Interpolation between inductive and projective limits of finite groups with applicatons to linear groups over finite fields; II.The characters of the groups of almost triangle matrices over finite filed; III.A Law of Large Numbers for the characters of GL_n(k) over finite field k; IV.An outline of construction of factor representations of the group GLB(F_q).
[ { "version": "v1", "created": "Thu, 24 May 2007 15:47:35 GMT" } ]
2007-05-25T00:00:00
[ [ "Vershik", "A.", "" ], [ "Kerov", "S.", "" ] ]
0705.3606
Paul M. Saffin
Paul M. Saffin and Anders Tranberg
Particle transfer in braneworld collisions
17 pages, 15 figures. New version has clearer discussion of boundary conditions, and corrects a typo
JHEP 0708:072,2007
10.1088/1126-6708/2007/08/072
DAMTP-2007-47
hep-th
null
We study the behaviour of fermions localized on moving kinks as these collide with either antikinks or spacetime boundaries. We numerically solve for the evolution of the scalar kinks and the bound (i.e. localized) fermion modes, and calculate the number of fermions transfered to the antikink and boundary in terms of Bogoliubov coefficients. Interpreting the boundary as the brane on which we live, this models the ability of fermions on branes incoming from the bulk to ``stick'' on the world brane, even when the incoming branes bounce back into the bulk.
[ { "version": "v1", "created": "Thu, 24 May 2007 15:49:01 GMT" }, { "version": "v2", "created": "Fri, 8 Jun 2007 10:25:02 GMT" } ]
2009-04-17T00:00:00
[ [ "Saffin", "Paul M.", "" ], [ "Tranberg", "Anders", "" ] ]
0705.3607
Peter Henselder
P. Henselder
Star Products for Relativistic Quantum Mechanics
10 pages
null
null
null
quant-ph
null
The star product formalism has proved to be an alternative formulation for nonrelativistic quantum mechanics. We want introduce here a covariant star product in order to extend the star product formalism to relativistic quantum mechanics in the proper time formulation.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:00:56 GMT" } ]
2007-05-25T00:00:00
[ [ "Henselder", "P.", "" ] ]
0705.3608
Eugen Radu
Eugen Radu, Ya. Shnir and D. H. Tchrakian
d=4+1 gravitating nonabelian solutions with bi-azimuthal symmetry
13 pages, 5 figures; v2: typos corrected, published version
Phys.Lett.B657:246-254,2007
10.1016/j.physletb.2007.10.016
DIAS-STP-07-07
hep-th gr-qc
null
We construct static, asymptotically flat solutions of SU(2) Einstein-Yang-Mills theory in 4+1 dimensions, subject to bi-azimuthal symmetry. Both particle-like and black hole solutions are considered for two different sets of boundary conditions in the Yang--Mills sector, corresponding to multisolitons and soliton-antisoliton pairs. For gravitating multi-soliton solutions, we find that their mass per unit charge is lower than the mass of the corresponding unit charge, spherically symmetric soliton.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:17:55 GMT" }, { "version": "v2", "created": "Tue, 27 Nov 2007 11:34:12 GMT" } ]
2008-11-26T00:00:00
[ [ "Radu", "Eugen", "" ], [ "Shnir", "Ya.", "" ], [ "Tchrakian", "D. H.", "" ] ]
0705.3609
Roberto Longo
Sebastiano Carpi, Yasuyuki Kawahigashi and Roberto Longo
Structure and Classification of Superconformal Nets
49 pages. Section 8 has been removed. More details concerning the diffeomorphism covariance are given
Annales Henri Poincare 9:1069-1121,2008
10.1007/s00023-008-0381-9
null
math-ph math.MP math.OA
null
We study the general structure of Fermi conformal nets of von Neumann algebras on the circle, consider a class of topological representations, the general representations, that we characterize as Neveu-Schwarz or Ramond representations, in particular a Jones index can be associated with each of them. We then consider a supersymmetric general representation associated with a Fermi modular net and give a formula involving the Fredholm index of the supercharge operator and the Jones index. We then consider the net associated with the super-Virasoro algebra and discuss its structure. If the central charge c belongs to the discrete series, this net is modular by the work of F. Xu and we get an example where our setting is verified by considering the Ramond irreducible representation with lowest weight c/24. We classify all the irreducible Fermi extensions of any super-Virasoro net in the discrete series, thus providing a classification of all superconformal nets with central charge less than 3/2.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:15:15 GMT" }, { "version": "v2", "created": "Mon, 3 Mar 2008 18:07:21 GMT" } ]
2009-04-17T00:00:00
[ [ "Carpi", "Sebastiano", "" ], [ "Kawahigashi", "Yasuyuki", "" ], [ "Longo", "Roberto", "" ] ]
0705.3610
Antoine Meyer
Greta Yorsh, Alexander Rabinovich, Mooly Sagiv, Antoine Meyer (LIAFA), Ahmed Bouajjani (LIAFA)
A Logic of Reachable Patterns in Linked Data-Structures
null
Foundations of Software Science and Computation Structures (29/03/2006) p. 94-110
10.1007/11690634_7
null
cs.LO
null
We define a new decidable logic for expressing and checking invariants of programs that manipulate dynamically-allocated objects via pointers and destructive pointer updates. The main feature of this logic is the ability to limit the neighborhood of a node that is reachable via a regular expression from a designated node. The logic is closed under boolean operations (entailment, negation) and has a finite model property. The key technical result is the proof of decidability. We show how to express precondition, postconditions, and loop invariants for some interesting programs. It is also possible to express properties such as disjointness of data-structures, and low-level heap mutations. Moreover, our logic can express properties of arbitrary data-structures and of an arbitrary number of pointer fields. The latter provides a way to naturally specify postconditions that relate the fields on entry to a procedure to the fields on exit. Therefore, it is possible to use the logic to automatically prove partial correctness of programs performing low-level heap mutations.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:10:52 GMT" } ]
2007-06-13T00:00:00
[ [ "Yorsh", "Greta", "", "LIAFA" ], [ "Rabinovich", "Alexander", "", "LIAFA" ], [ "Sagiv", "Mooly", "", "LIAFA" ], [ "Meyer", "Antoine", "", "LIAFA" ], [ "Bouajjani", "Ahmed", "", "LIAFA" ] ]
0705.3611
David Russell
D. M. Russell (1), R. P. Fender (1), P. G. Jonker (2) ((1) University of Southampton (2) SRON, Harvard CfA, Utrecht University)
Evidence for a jet contribution to the optical/infrared light of neutron star X-ray binaries
MNRAS accepted, 10 pages, 4 figures
Mon.Not.Roy.Astron.Soc.379:1108-1116,2007
10.1111/j.1365-2966.2007.12008.x
null
astro-ph
null
Optical/near-infrared (optical/NIR; OIR) light from low-mass neutron star X-ray binaries (NSXBs) in outburst is traditionally thought to be thermal emission from the accretion disc. Here we present a comprehensive collection of quasi-simultaneous OIR and X-ray data from 19 low-magnetic field NSXBs, including new observations of three sources: 4U 0614+09, LMC X-2 and GX 349+2. The average radio-OIR spectrum for NSXBs is alpha ~ +0.2 (where L_nu propto nu^alpha) at least at high luminosities when the radio jet is detected. This is comparable to, but slightly more inverted than the alpha ~ 0.0 found for black hole X-ray binaries. The OIR spectra and relations between OIR and X-ray fluxes are compared to those expected if the OIR emission is dominated by thermal emission from an X-ray or viscously heated disc, or synchrotron emission from the inner regions of the jets. We find that thermal emission due to X-ray reprocessing can explain all the data except at high luminosities for some NSXBs, namely the atolls and millisecond X-ray pulsars (MSXPs). Optically thin synchrotron emission from the jets (with an observed OIR spectral index of alpha_thin < 0) dominate the NIR light above L_x ~ 10^36 erg/s and the optical above L_x ~ 10^37 erg/s in these systems. For NSXB Z-sources, the OIR observations can be explained by X-ray reprocessing alone, although synchrotron emission may make a low level contribution to the NIR, and could dominate the OIR in one or two cases.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:11:44 GMT" } ]
2009-06-23T00:00:00
[ [ "Russell", "D. M.", "" ], [ "Fender", "R. P.", "" ], [ "Jonker", "P. G.", "" ] ]
0705.3612
Christopher Pooley
C. M. Pooley, G. P. Alexander, and J. M. Yeomans
Swimming with a friend at low Reynolds number
6 pages, 4 figures
null
null
null
cond-mat.soft cond-mat.other physics.bio-ph q-bio.OT
null
We investigate the hydrodynamic interactions between microorganisms swimming at low Reynolds number. By considering simple model swimmers, and combining analytic and numerical approaches, we investigate the time-averaged flow field around a swimmer. At short distances the swimmer behaves like a pump. At large distances the velocity field depends on whether the swimming stroke is invariant under a combined time-reversal and parity transformation. We then consider two swimmers and find that the interaction between them consists of two parts; a dead term, independent of the motion of the second swimmer, which takes the expected dipolar form and a live term resulting from the simultaneous swimming action of both swimmers which does not. We argue that, in general, the latter dominates. The swimmer--swimmer interaction is a complicated function of their relative displacement, orientation and phase, leading to motion that can be attractive, repulsive or oscillatory.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:11:59 GMT" } ]
2007-05-25T00:00:00
[ [ "Pooley", "C. M.", "" ], [ "Alexander", "G. P.", "" ], [ "Yeomans", "J. M.", "" ] ]
0705.3613
Claudio Ciofi degli Atti
M. Alvioli, C. Ciofi degli Atti, I. Marchino, H. Morita, V. Palli
Effects of correlations on the total neutron-Nucleus cross section at high energies
14 pages, 5 figures
null
null
null
nucl-th
null
The total neutron-Nucleus cross section has been calculated within an approach which takes into account nucleon-nucleon correlations, Glauber multiple scattering and inelastic shadowing corrections. Nuclear targets ranging from 4He to 208Pb and neutron incident momentum ranging from 3 to 300 GeV/c, have been considered. Correlations have been introduced by two different approaches leading to the same results. The commonly used approximation, consisting in treating nuclear effects only by a product of one-body densities, is carefully analyzed and it is shown that the effects of realistic correlations resulting from modern nucleon-nucleon interactions and realistic correlations resulting from realistic nucleon-nucleon interactions and microscopic ground state calculation of nuclear properties cannot be disregarded.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:39:15 GMT" } ]
2007-05-25T00:00:00
[ [ "Alvioli", "M.", "" ], [ "Atti", "C. Ciofi degli", "" ], [ "Marchino", "I.", "" ], [ "Morita", "H.", "" ], [ "Palli", "V.", "" ] ]
0705.3614
Lawren Smithline
Lawren Smithline
Bounding slopes of $p$-adic modular forms
15 pages. June 2001 preprint
null
null
null
math.AG
null
Let $p$ be prime, $N$ be a positive integer prime to $p$, and $k$ be an integer. Let $P_k(t)$ be the characteristic series for Atkin's $U$ operator as an endomorphism of $p$-adic overconvergent modular forms of tame level $N$ and weight $k$. Motivated by conjectures of Gouvea and Mazur, we strengthen Wan's congruence between coefficients of $P_k$ and $P_{k'}$ for $k'$ close $p$-adically to $k$. For $p-1 | 12$, $N = 1$, $k = 0$, we compute a matrix for $U$ whose entries are coefficients in the power series of a rational function of two variables. We apply this computation to show for $p = 3$ a parabola below the Newton polygon $N_0$ of $P_0$, which coincides with $N_0$ infinitely often. As a consequence, we find a polygonal curve above $N_0$. This tightest bound on $N_0$ yields the strongest congruences between coefficients of $P_0$ and $P_k$ for $k$ of large 3-adic valuation.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:25:56 GMT" } ]
2007-05-25T00:00:00
[ [ "Smithline", "Lawren", "" ] ]
0705.3615
Christian Buth
Christian Buth, Robin Santra, Linda Young
Electromagnetically induced transparency for x rays
5 pages, 3 figures, RevTeX4, corrected typos
Phys.Rev.Lett.98:253001,2007
10.1103/PhysRevLett.98.253001
null
physics.atom-ph physics.ins-det physics.optics
null
Electromagnetically induced transparency (EIT) is predicted for x rays in laser-dressed neon gas. The x-ray photoabsorption cross section and polarizability near the Ne K edge are calculated using an ab initio theory suitable for optical strong-field problems. The laser wavelength is tuned close to the transition between 1s^-1 3s and 1s^-1 3p (approximately 800nm). The minimum laser intensity required to observe EIT is of the order of 10^12 W/cm^2. The ab initio results are discussed in terms of an exactly solvable three-level model. This work opens new opportunities for research with ultrafast x-ray sources.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:16:32 GMT" }, { "version": "v2", "created": "Mon, 25 Jun 2007 14:15:02 GMT" } ]
2008-11-26T00:00:00
[ [ "Buth", "Christian", "" ], [ "Santra", "Robin", "" ], [ "Young", "Linda", "" ] ]
0705.3616
Andy Zaidman
Andy Zaidman, Bart Van Rompaey, Serge Demeyer, Arie van Deursen
On How Developers Test Open Source Software Systems
null
null
null
TUD-SERG-2007-012
cs.SE
null
Engineering software systems is a multidisciplinary activity, whereby a number of artifacts must be created - and maintained - synchronously. In this paper we investigate whether production code and the accompanying tests co-evolve by exploring a project's versioning system, code coverage reports and size-metrics. Three open source case studies teach us that testing activities usually start later on during the lifetime and are more "phased", although we did not observe increasing testing activity before releases. Furthermore, we note large differences in the levels of test coverage given the proportion of test code.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:21:35 GMT" } ]
2007-05-25T00:00:00
[ [ "Zaidman", "Andy", "" ], [ "Van Rompaey", "Bart", "" ], [ "Demeyer", "Serge", "" ], [ "van Deursen", "Arie", "" ] ]
0705.3617
Claudio Ciofi degli Atti
M. Alvioli, C. Ciofi degli Atti, V. Palli, L.P. Kaptari
Final State Interaction Effects in Semi-inclusive Deep Inelastic processes A(e,e'p)X off the deuteron and complex nuclei
19 pages, 10 figures, corrected reference
null
null
null
nucl-th hep-ph
null
The effects of the final state interaction (FSI) in semi inclusive deep inelastic electron scattering processes $A(e,e'p)X$ off nuclei are investigated in details. Proton production is described within the spectator and the target fragmentation mechanisms whose relevance to the experimental study of the deep inelastic structure functions of bound nucleons and the non perturbative hadronization process is analyzed. Particular attention is paid to the deuteron target within kinematical conditions corresponding to the available and forthcoming experimental data at Jlab. We argue that there are kinematical regions where FSI effects are minimized, allowing for a reliable investigation of the DIS structure functions, and regions where the interaction of the quark-gluon debris with nucleons is maximized, which makes it possible to study hadronization mechanisms. Nuclear structure has been described by means of realistic wave functions and spectral functions and the final state interaction has been treated within an eikonal approximation approach which takes into account the rescattering of the quark-gluon debris with the residual nucleus and, in the case of complex nuclei, within an optical potential approach to account for the FSI of the struck proton.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:24:39 GMT" }, { "version": "v2", "created": "Fri, 1 Jun 2007 09:54:28 GMT" } ]
2007-06-13T00:00:00
[ [ "Alvioli", "M.", "" ], [ "Atti", "C. Ciofi degli", "" ], [ "Palli", "V.", "" ], [ "Kaptari", "L. P.", "" ] ]
0705.3618
Wei-Cheng Lee
Wei-Cheng Lee, A.H. MacDonald
Electronic Interface Reconstruction at Polar-Nonpolar Mott Insulator Heterojunctions
7 pages, 6 figures, some typos corrected
Phys. Rev. B 76, 075339 (2007)
10.1103/PhysRevB.76.075339
null
cond-mat.str-el cond-mat.mtrl-sci
null
We report on a theoretical study of the electronic interface reconstruction (EIR) induced by polarity discontinuity at a heterojunction between a polar and a nonpolar Mott insulators, and of the two-dimensional strongly-correlated electron systems (2DSCESs) which accompany the reconstruction. We derive an expression for the minimum number of polar layers required to drive the EIR, and discuss key parameters of the heterojunction system which control 2DSCES properties. The role of strong correlations in enhancing confinement at the interface is emphasized.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:40:43 GMT" }, { "version": "v2", "created": "Wed, 22 Aug 2007 14:22:49 GMT" } ]
2009-11-13T00:00:00
[ [ "Lee", "Wei-Cheng", "" ], [ "MacDonald", "A. H.", "" ] ]
0705.3619
Dr. Anirudh Pradhan
Anirudh Pradhan, A. K. Yadav, R. P. Singh and V. K. Singh
A New Class of Inhomogeneous String Cosmological Models in General Relativity
12 pages, no figure. Submitted to Astrophys. Space Sci. arXiv admin note: substantial text overlap with arXiv:0705.0904
Astrophys.SpaceSci.312:145-150,2007
10.1007/s10509-007-9665-7
null
gr-qc
null
A new class of solutions of Einstein field equations has been investigated for inhomogeneous cylindrically symmetric space-time with string source. To get the deterministic solution, it has been assumed that the expansion ($\theta$) in the model is proportional to the eigen value $\sigma^{1}_{1}$ of the shear tensor $\sigma^{i}_{j}$. Certain physical and geometric properties of the models are also discussed.
[ { "version": "v1", "created": "Thu, 24 May 2007 16:34:46 GMT" } ]
2014-05-06T00:00:00
[ [ "Pradhan", "Anirudh", "" ], [ "Yadav", "A. K.", "" ], [ "Singh", "R. P.", "" ], [ "Singh", "V. K.", "" ] ]
0705.3620
Darren Golbourn
Leor Barack and Darren A Golbourn
Scalar-field perturbations from a particle orbiting a black hole using numerical evolution in 2+1 dimensions
Accepted for publication in PRD, minor typographical corrections, references updated, 25 pages, 22 eps figures
Phys.Rev.D76:044020,2007
10.1103/PhysRevD.76.044020
null
gr-qc
null
We present a new technique for time-domain numerical evolution of the scalar field generated by a pointlike scalar charge orbiting a black hole. Time-domain evolution offers an efficient way for calculating black hole perturbations, especially as input for computations of the local self force acting on orbiting particles. In Kerr geometry, the field equations are not fully separable in the time domain, and one has to tackle them in 2+1 dimensions (two spatial dimensions and time; the azimuthal dependence is still separable). A technical difficulty arises when the source of the field is a pointlike particle, as the 2+1-dimensional perturbation is then singular: Each of the azimuthal modes diverges logarithmically at the particle. To deal with this problem we split the numerical domain into two regions: Inside a thin worldtube surrounding the particle's worldline we solve for a regularized variable, obtained from the full field by subtracting out a suitable ``puncture'' function, given analytically. Outside this worldtube we solve for the full, original field. The value of the evolution variable is adjusted across the boundary of the worldtube. In this work we demonstrate the applicability of this method in the example of circular orbits around a Schwarzschild black hole (refraining from exploiting the spherical symmetry of the background, and working in 2+1 dimensions).
[ { "version": "v1", "created": "Thu, 24 May 2007 16:51:44 GMT" }, { "version": "v2", "created": "Mon, 20 Aug 2007 15:03:36 GMT" } ]
2008-11-26T00:00:00
[ [ "Barack", "Leor", "" ], [ "Golbourn", "Darren A", "" ] ]
0705.3621
Sebastien Fromang
S.Fromang, J.Papaloizou
MHD simulations of the magnetorotational instability in a shearing box with zero net flux. I. The issue of convergence
10 pages, 15 figures, accepted in A&A. Numerical results improved, various numerical issues addressed (boundary conditions, box size, run durations)
null
10.1051/0004-6361:20077942
null
astro-ph
null
We study the properties of MHD turbulence driven by the magnetorotational instability (MRI) in accretion disks. We adopt the local shearing box model and focus on the special case for which the initial magnetic flux threading the disk vanishes. We employ the finite difference code ZEUS to evolve the ideal MHD equations. Performing a set of numerical simulations in a fixed computational domain with increasing resolution, we demonstrate that turbulent activity decreases as resolution increases. We quantify the turbulent activity by measuring the rate of angular momentum transport through evaluating the standard alpha parameter. We find alpha=0.004 when (N_x,N_y,N_z)=(64,100,64), alpha=0.002 when (N_x,N_y,N_z)=(128,200,128) and alpha=0.001 when (N_x,N_y,N_z)=(256,400,256). This steady decline is an indication that numerical dissipation, occurring at the grid scale is an important determinant of the saturated form of the MHD turbulence. Analysing the results in Fourier space, we demonstrate that this is due to the MRI forcing significant flow energy all the way down to the grid dissipation scale. We also use our results to study the properties of the numerical dissipation in ZEUS. Its amplitude is characterised by the magnitude of an effective magnetic Reynolds number Re_M which increases from 10^4 to 10^5 as the number of grid points is increased from 64 to 256 per scale height. The simulations we have carried out do not produce results that are independent of the numerical dissipation scale, even at the highest resolution studied. Thus it is important to use physical dissipation, both viscous and resistive, and to quantify contributions from numerical effects, when performing numerical simulations of MHD turbulence with zero net flux in accretion disks at the resolutions normally considered.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:01:01 GMT" }, { "version": "v2", "created": "Thu, 4 Oct 2007 10:07:40 GMT" } ]
2009-11-13T00:00:00
[ [ "Fromang", "S.", "" ], [ "Papaloizou", "J.", "" ] ]
0705.3622
Sebastien Fromang
S. Fromang, J. Papaloizou, G. Lesur, T. Heinemann
MHD simulations of the magnetorotational instability in a shearing box with zero net flux. II. The effect of transport coefficients
10 pages, 13 figures, accepted in A&A. Numerical results improved, minor changes in the text
null
10.1051/0004-6361:20077943
null
astro-ph
null
We study the influence of the choice of transport coefficients (viscosity and resistivity) on MHD turbulence driven by the magnetorotational instability (MRI) in accretion disks. We follow the methodology described in paper I: we adopt an unstratified shearing box model and focus on the case where the net vertical magnetic flux threading the box vanishes. For the most part we use the finite difference code ZEUS, including explicit transport coefficients in the calculations. However, we also compare our results with those obtained using other algorithms (NIRVANA, the PENCIL code and a spectral code) to demonstrate both the convergence of our results and their independence of the numerical scheme. We find that small scale dissipation affects the saturated state of MHD turbulence. In agreement with recent similar numerical simulations done in the presence of a net vertical magnetic flux, we find that turbulent activity (measured by the rate of angular momentum transport) is an increasing function of the magnetic Prandtl number Pm for all values of the Reynolds number Re that we investigated. We also found that turbulence disappears when the Prandtl number falls below a critical value Pm_c that is apparently a decreasing function of Re. For the limited region of parameter space that can be probed with current computational resources, we always obtained Pm_c>1. We conclude that the magnitudes of the transport coefficients are important in determining the properties of MHD turbulence in numerical simulations in the shearing box with zero net flux, at least for Reynolds numbers and magnetic Prandtl numbers that are such that transport is not dominated by numerical effects and thus can be probed using current computational resources.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:02:26 GMT" }, { "version": "v2", "created": "Thu, 4 Oct 2007 10:13:30 GMT" } ]
2009-11-13T00:00:00
[ [ "Fromang", "S.", "" ], [ "Papaloizou", "J.", "" ], [ "Lesur", "G.", "" ], [ "Heinemann", "T.", "" ] ]
0705.3623
Dr. Anirudh Pradhan
Anirudh Pradhan, S. K. Singh and L. J. S. Yadav
String Cosmological Model in Cylindrically Symmetric Inhomogeneous Universe with Electromagnetic Field II
12 pages, no figure. Submitted to Rom. Rep. Phys. arXiv admin note: substantial text overlap with arXiv:0705.0904
Rom.Rep.Phys.60:1013,2008
null
null
gr-qc
null
Cylindrically symmetric inhomogeneous string cosmological model of the universe in presence of electromagnetic field is investigated. We have assumed that F_{12} is the only non-vanishing component of electromagnetic field tensor F_{ij}. The Maxwell's equations show that F_{12} is the function of $x$ alone whereas the magnetic permeability is the function of x and t both. To get the deterministic solution, it has been assumed that the expansion ($\theta$) in the model is proportional to the eigen value $\sigma^{1}_{1}$ of the shear tensor $\sigma^{i}_{j}$. Some physical and geometric prperties of the model are also discussed.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:10:45 GMT" }, { "version": "v2", "created": "Sun, 29 Jul 2007 07:22:42 GMT" } ]
2014-05-06T00:00:00
[ [ "Pradhan", "Anirudh", "" ], [ "Singh", "S. K.", "" ], [ "Yadav", "L. J. S.", "" ] ]
0705.3624
Lukas Jelinek
J. D. Baena, L. Jelinek, R. Marques
Towards a systematic design of isotropic bulk magnetic metamaterials using the cubic point groups of symmetry
Submitted to Physical Review B, 23 pages
Phys. Rev. B 76, 245115, 2007
10.1103/PhysRevB.76.245115
null
physics.optics
null
In this paper a systematic approach to the design of bulk isotropic magnetic metamaterials is presented. The role of the symmetries of both the constitutive element and the lattice are analyzed. For this purpose it is assumed that the metamaterial is composed by cubic SRR resonators, arranged in a cubic lattice. The minimum symmetries needed to ensure an isotropic behavior are analyzed, and some particular configurations are proposed. Besides, an equivalent circuit model is proposed for the considered cubic SRR resonators. Experiments are carried out in order to validate the proposed theory. We hope that this analysis will pave the way to the design of bulk metamaterials with strong isotropic magnetic response, including negative permeability and left-handed metamaterials.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:18:14 GMT" } ]
2014-09-10T00:00:00
[ [ "Baena", "J. D.", "" ], [ "Jelinek", "L.", "" ], [ "Marques", "R.", "" ] ]
0705.3625
Kostyantyn Ropotenko
K.Ropotenko
Universal Bound on Dynamical Relaxation Time from Condition for Relaxing Quantity to be Classical
3 pages, no figures
null
null
null
gr-qc
null
It is shown that the Hod's universal bound on the relaxation time of a perturbed system \cite{hod} can be derived from a well-known condition for a relaxing quantity to be classical in the fluctuation theory.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:27:19 GMT" }, { "version": "v2", "created": "Thu, 7 Jun 2007 17:56:00 GMT" } ]
2007-06-07T00:00:00
[ [ "Ropotenko", "K.", "" ] ]
0705.3626
Juan Carlos Su\'arez
J.C. Suarez, E. Michel, G. Houdek, F. Perez Hernandez, and Y. Lebreton
Mode stability in delta Scuti stars: linear analysis versus observations in open clusters
8 pages, 4 figures, 3 tables. (MNRAS, in press)
Mon.Not.Roy.Astron.Soc.379:201-208,2007
10.1111/j.1365-2966.2007.11927.x
null
astro-ph
null
A comparison between linear stability analysis and observations of pulsation modes in five delta Scuti stars, belonging to the same cluster, is presented. The study is based on the work by Michel et al. (1999), in which such a comparison was performed for a representative set of model solutions obtained independently for each individual star considered. In this paper we revisit the work by Michel et al. (1999) following, however, a new approach which consists in the search for a single, complete, and coherent solution for all the selected stars, in order to constrain and test the assumed physics describing these objects. To do so, refined descriptions for the effects of rotation on the determination of the global stellar parameters and on the adiabatic oscillation frequency computations are used. In addition, a crude attempt is made to study the role of rotation on the prediction of mode instabilities.The present results are found to be comparable with those reported by Michel et al. (1999). Within the temperature range log T_eff = 3.87-3.88 agreement between observations and model computations of unstable modes is restricted to values for the mixing-length parameter alpha_nl less or equal to 1.50. This indicates that for these stars a smaller value for alpha_nl is required than suggested from a calibrated solar model. We stress the point that the linear stability analysis used in this work still assumes stellar models without rotation and that further developments are required for a proper description of the interaction between rotation and pulsation dynamics.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:29:38 GMT" } ]
2009-06-23T00:00:00
[ [ "Suarez", "J. C.", "" ], [ "Michel", "E.", "" ], [ "Houdek", "G.", "" ], [ "Hernandez", "F. Perez", "" ], [ "Lebreton", "Y.", "" ] ]
0705.3627
Ansgar Liebsch
A. Liebsch and H. Ishida
Coulomb correlations do not fill the e'_g hole pockets in Na_{0.3}CoO_2
4 pages, 2 figures
Eur. Phys. J. B 61, 405-411 (2008)
10.1140/epjb/e2008-00108-y
null
cond-mat.str-el
null
There exists presently considerable debate over the question whether local Coulomb interactions can explain the absence of the small e'_g Fermi surface hole pockets in photoemission studies of Na_{0.3}CoO_2. By comparing dynamical mean field results for different single particle Hamiltonians and exact diagonalization as well as quantum Monte Carlo treatments, we show that, for realistic values of the Coulomb energy U and Hund exchange J, the e'_g pockets can be slightly enhanced or reduced compared to band structure predictions, but they do not disappear.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:29:40 GMT" } ]
2009-11-13T00:00:00
[ [ "Liebsch", "A.", "" ], [ "Ishida", "H.", "" ] ]
0705.3628
Roman G. Smirnov
Joshua D. MacArthur, Raymond G. McLenaghan and Roman G. Smirnov
Hamilton-Jacobi Theory and Moving Frames
This is a contribution to the Vadim Kuznetsov Memorial Issue on Integrable Systems and Related Topics, published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA/
SIGMA 3 (2007), 070, 23 pages
10.3842/SIGMA.2007.070
null
math-ph math.DG math.MP nlin.SI
null
The interplay between the Hamilton-Jacobi theory of orthogonal separation of variables and the theory of group actions is investigated based on concrete examples.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:29:50 GMT" } ]
2008-04-24T00:00:00
[ [ "MacArthur", "Joshua D.", "" ], [ "McLenaghan", "Raymond G.", "" ], [ "Smirnov", "Roman G.", "" ] ]
0705.3629
Barry Simon
Fritz Gesztesy, Alexander Pushnitski, and Barry Simon
On the Koplienko spectral shift function, I. Basics
Submitted to the Marchenko and Pastur birthday issue of Journal of Mathematical Physics, Analysis and Geometry
null
null
null
math.SP math-ph math.MP
null
We study the Koplienko Spectral Shift Function (KoSSF), which is distinct from the one of Krein (KrSSF). KoSSF is defined for pairs $A,B$ with $(A-B)\in\calI_2$, the Hilbert-Schmidt operators, while KrSSF is defined for pairs $A,B$ with $(A-B)\in\calI_1$, the trace class operators. We review various aspects of the construction of both KoSSF and KrSSF. Among our new results are: (i) that any positive Riemann integrable function of compact support occurs as a KoSSF; (ii) that there exist $A,B$ with $(A-B)\in\calI_2$ so $\det_2((A-z)(B-z)^{-1})$ does not have nontangential boundary values; (iii) an alternative definition of KoSSF in the unitary case; and (iv) a new proof of the invariance of the a.c. spectrum under $\calI_1$-perturbations that uses the KrSSF.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:36:55 GMT" } ]
2007-05-25T00:00:00
[ [ "Gesztesy", "Fritz", "" ], [ "Pushnitski", "Alexander", "" ], [ "Simon", "Barry", "" ] ]
0705.3630
Merab Gogberashvili Dr
V. R. Garsevanishvili, A. A. Khelashvili, Z. R. Menteshashvili and M. S. Nioradze
Light Front Formalism for Composite Systems and Some of Its Applications in Particle and Relativistic Nuclear Physics
Review paper, Submitted to Phys. Rep., 89 pages, 23 figures
Phys.Rept.458:247-300,2008
10.1016/j.physrep.2007.11.002
null
hep-th hep-ph nucl-th
null
Light front formalism for composite systems is presented. Derivation of equations for bound state and scattering problems are given. Methods of constructing of elastic form factors and scattering amplitudes of composite particles are reviewed. Elastic form factors in the impulse approximation are calculated. Scattering amplitudes for relativistic bound states are constructed. Some model cases for transition amplitudes are considered. Deep inelastic form factors (structure functions) are expressed through light front wave functions. It is shown that taking into account of transverse motion of partons leads to the violation of Bjorken scaling and structure functions become square of transverse momentum dependent. Possible explanation of the EMC-effect is given. Problem of light front relativization of wave functions of lightest nuclei is considered. Scaling properties of deuteron, ${}^3He$ and ${}^4He$ light front wave functions are checked in a rather wide energy range.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:54:13 GMT" } ]
2008-11-26T00:00:00
[ [ "Garsevanishvili", "V. R.", "" ], [ "Khelashvili", "A. A.", "" ], [ "Menteshashvili", "Z. R.", "" ], [ "Nioradze", "M. S.", "" ] ]
0705.3631
Francisco Santos
Pilar Sabariego, Francisco Santos
Triple-loop networks with arbitrarily many minimum distance diagrams
17 pages, 8 figures
Discrete Mathematics, 309(6), April 2009, 1672-1684.
10.1016/j.disc.2008.02.047
null
math.CO cs.DM math.OC
null
Minimum distance diagrams are a way to encode the diameter and routing information of multi-loop networks. For the widely studied case of double-loop networks, it is known that each network has at most two such diagrams and that they have a very definite form "L-shape''. In contrast, in this paper we show that there are triple-loop networks with an arbitrarily big number of associated minimum distance diagrams. For doing this, we build-up on the relations between minimum distance diagrams and monomial ideals.
[ { "version": "v1", "created": "Thu, 24 May 2007 17:59:33 GMT" } ]
2009-07-07T00:00:00
[ [ "Sabariego", "Pilar", "" ], [ "Santos", "Francisco", "" ] ]
0705.3632
Roland Bacher
Roland Bacher (IF)
Arithmetic properties related to the shuffle-product
20 pages, contains experimental data
null
null
null
math.NT
null
Properties of the shuffle product suggest the definition of a quadratic form with domain and values in formal power series over a field of characteristic 2. This quadratic form preserves rational (respectively algebraic) power series and its restriction to the affine subspace of series with constant term 1 is bijective. Conjecturally, this bijection restricts to a bijection of rational (respectively algebraic) formal power series.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:04:02 GMT" }, { "version": "v2", "created": "Thu, 7 Jun 2007 12:16:02 GMT" } ]
2007-06-07T00:00:00
[ [ "Bacher", "Roland", "", "IF" ] ]
0705.3633
Giovanni Peccati
Giovanni Peccati (LSTA), Marc Yor (PMA)
Burkholder's submartingales from a stochastic calculus perspective
7 pages
null
null
null
math.PR
null
We provide a simple proof, as well as several generalizations, of a recent result by Davis and Suh, characterizing a class of continuous submartingales and supermartingales that can be expressed in terms of a squared Brownian motion and of some appropriate powers of its maximum. Our techniques involve elementary stochastic calculus, as well as the Doob-Meyer decomposition of continuous submartingales. These results can be used to obtain an explicit expression of the constants appearing in the Burkholder-Davis-Gundy inequalities. A connection with some balayage formulae is also established.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:05:00 GMT" } ]
2007-05-25T00:00:00
[ [ "Peccati", "Giovanni", "", "LSTA" ], [ "Yor", "Marc", "", "PMA" ] ]
0705.3634
Athena Stacy
Athena Stacy, Volker Bromm
Impact of Cosmic Rays on Population III Star Formation
MNRAS in press, 12 pages, 6 figures
null
10.1111/j.1365-2966.2007.12247.x
null
astro-ph
null
We explore the implications of a possible cosmic ray (CR) background generated during the first supernova explosions that end the brief lives of massive Population III stars. We show that such a CR background could have significantly influenced the cooling and collapse of primordial gas clouds in minihaloes around redshifts of z ~ 15 - 20, provided the CR flux was sufficient to yield an ionization rate greater than about 10^-19 s^-1 near the center of the minihalo. The presence of CRs with energies less than approximately 10^7 eV would indirectly enhance the molecular cooling in these regions, and we estimate that the resulting lower temperatures in these minihaloes would yield a characteristic stellar mass as low as ~ 10 M_sun. CRs have a less pronounced effect on the cooling and collapse of primordial gas clouds inside more massive dark matter haloes with virial masses greater than approximately 10^8 M_sun at the later stages of cosmological structure formation around z ~ 10 - 15. In these clouds, even without CR flux the molecular abundance is already sufficient to allow cooling to the floor set by the temperature of the cosmic microwave background.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:10:55 GMT" }, { "version": "v2", "created": "Fri, 25 May 2007 07:52:10 GMT" }, { "version": "v3", "created": "Mon, 23 Jul 2007 16:18:55 GMT" } ]
2009-11-13T00:00:00
[ [ "Stacy", "Athena", "" ], [ "Bromm", "Volker", "" ] ]
0705.3635
Rudi Hackl
L. Tassini, W. Prestel, A. Erb, M. Lambacher, R. Hackl
First-Order Type Effects in YBa$_2$Cu$_3$O$_{6+x}$ at the Onset of Superconductivity
4 pages, 4 figures
Phys. Rev. B 78, 020511(R) (2008)
10.1103/PhysRevB.78.020511
null
cond-mat.supr-con cond-mat.str-el
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present results of Raman scattering experiments on tetragonal ${\rm (Y_{1-y}Ca_{y})Ba_{2}Cu_{3}O_{6+x}}$ for doping levels $p(x,y)$ between 0 and 0.07 holes/CuO$_2$. Below the onset of superconductivity at $p_{\rm sc1} \approx 0.06$, we find evidence of a diagonal superstructure. At $p_{\rm sc1}$, lattice and electron dynamics change discontinuously with the charge and spin properties being renormalized at all energy scales. The results indicate that charge ordering is intimately related to the transition at $p_{\rm sc1}$ and that the maximal transition temperature to superconductivity at optimal doping $T_{c}^{\rm max}$ depends on the type of ordering at $p>p_{\rm sc1}$.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:53:32 GMT" }, { "version": "v2", "created": "Wed, 27 Aug 2008 13:33:52 GMT" } ]
2008-08-27T00:00:00
[ [ "Tassini", "L.", "" ], [ "Prestel", "W.", "" ], [ "Erb", "A.", "" ], [ "Lambacher", "M.", "" ], [ "Hackl", "R.", "" ] ]
0705.3636
Hooman Davoudiasl
Hooman Davoudiasl
Constraining Unparticle Physics with Cosmology and Astrophysics
4 pages, RevTex4. Two figures and a reference added. Some minor changes. Main results and conclusions unchanged. Version accepted for publication by PRL
Phys.Rev.Lett.99:141301,2007
10.1103/PhysRevLett.99.141301
BNL-HET-07/8
hep-ph astro-ph
null
It has recently been suggested that a scale invariant "unparticle" sector with a non-trivial infrared fixed point may couple to the Standard Model (SM) via higher dimensional operators. The weakness of such interactions hides the the unparticle phenomena at low energies. We demonstrate how cosmology and astrophysics can place significant bounds on the strength of unparticle-SM interactions. We also discuss the possibility of a having a non-negligible unparticle relic density today.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:35:31 GMT" }, { "version": "v2", "created": "Thu, 24 May 2007 23:41:20 GMT" }, { "version": "v3", "created": "Wed, 20 Jun 2007 20:26:53 GMT" }, { "version": "v4", "created": "Fri, 21 Sep 2007 15:52:49 GMT" } ]
2008-11-26T00:00:00
[ [ "Davoudiasl", "Hooman", "" ] ]
0705.3637
Mamta Dahiya Dr.
Debajyoti Choudhury, Dilip Kumar Ghosh, Mamta
Unparticles and Muon Decay
13 pages, 6 figures
Phys.Lett.B658:148-154,2008
10.1016/j.physletb.2007.07.067
null
hep-ph
null
Recently Georgi has discussed the possible existence of `Unparticles' describable by operators having non-integral scaling dimensions. With the interaction of these with the Standard Model (SM) particles being constrained only by gauge and Lorentz symmetries, it affords a new source for lepton flavour violation. Current and future muon decay experiments are shown to be very sensitive to such scenarios.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:41:35 GMT" } ]
2008-11-26T00:00:00
[ [ "Choudhury", "Debajyoti", "" ], [ "Ghosh", "Dilip Kumar", "" ], [ "Mamta", "", "" ] ]
0705.3638
Eilat Glikman
Eilat Glikman (1), S. G. Djorgovski (1), Daniel Stern (2), Milan Bogosavljevic (1), and Ashish Mahabal (1) ((1) Caltech, (2) JPL)
Discovery of Two Spectroscopically Peculiar, Low-Luminosity Quasars at z~4
15 pages, 5 figures, Accepted for publicated in ApJ Letters
null
10.1086/520085
null
astro-ph
null
We report the discovery of two low-luminosity quasars at z~4, both of which show prominent N IV] 1486A emission. This line is extremely rare in quasar spectra at any redshift; detecting it in two out of a sample of 23 objects (i.e., ~ 9% of the sample) is intriguing and is likely due to the low-luminosity, high-redshift quasar sample we are studying. This is still a poorly explored regime, where contributions from associated, early starbursts may be significant. One interpretation of this line posits photoionization by very massive young stars. Seeing N IV] 1486A emission in a high-redshift quasar may thus be understood in the context of co-formation and early co-evolution of galaxies and their supermassive black holes. Alternatively, we may be seeing a phenomenon related to the early evolution of quasar broad emission line regions. The non-detection (and possibly even broad absorption) of N V 1240A line in the spectrum of one of these quasars may support that interpretation. These two objects may signal a new faint quasar population or an early AGN evolutionary stage at high redshifts.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:45:16 GMT" } ]
2019-08-19T00:00:00
[ [ "Glikman", "Eilat", "", "Caltech" ], [ "Djorgovski", "S. G.", "", "Caltech" ], [ "Stern", "Daniel", "", "JPL" ], [ "Bogosavljevic", "Milan", "", "Caltech" ], [ "Mahabal", "Ashish", "", "Caltech" ] ]
0705.3639
Benjamin Lev
Benjamin L. Lev, Andras Vukics, Eric R. Hudson, Brian C. Sawyer, Peter Domokos, Helmut Ritsch, and Jun Ye
Prospects for the cavity-assisted laser cooling of molecules
18 pages, 10 figures
better, condensed version published in PRA 77, 023402 (2008)
10.1103/PhysRevA.77.023402
null
quant-ph physics.atom-ph
null
Cooling of molecules via free-space dissipative scattering of photons is thought not to be practicable due to the inherently large number of Raman loss channels available to molecules and the prohibitive expense of building multiple repumping laser systems. The use of an optical cavity to enhance coherent Rayleigh scattering into a decaying cavity mode has been suggested as a potential method to mitigate Raman loss, thereby enabling the laser cooling of molecules to ultracold temperatures. We discuss the possibility of cavity-assisted laser cooling particles without closed transitions, identify conditions necessary to achieve efficient cooling, and suggest solutions given experimental constraints. Specifically, it is shown that cooperativities much greater than unity are required for cooling without loss, and that this could be achieved via the superradiant scattering associated with intracavity self-localization of the molecules. Particular emphasis is given to the polar hydroxyl radical (OH), cold samples of which are readily obtained from Stark deceleration.
[ { "version": "v1", "created": "Thu, 24 May 2007 19:06:21 GMT" } ]
2009-11-13T00:00:00
[ [ "Lev", "Benjamin L.", "" ], [ "Vukics", "Andras", "" ], [ "Hudson", "Eric R.", "" ], [ "Sawyer", "Brian C.", "" ], [ "Domokos", "Peter", "" ], [ "Ritsch", "Helmut", "" ], [ "Ye", "Jun", "" ] ]
0705.3640
Barry Simon
Barry Simon
Critical Lieb-Thirring bounds for one-dimensional Schrodinger operators and Jacobi matrices with regular ground states
This paper has been withdrawn
null
null
null
math.SP math-ph math.MP
null
This paper has been withdrawn by the author in favor of a stronger result proven by the author with R. Frank and T. Weidl in arXiv:0707.0998
[ { "version": "v1", "created": "Thu, 24 May 2007 18:50:13 GMT" }, { "version": "v2", "created": "Mon, 9 Jul 2007 17:56:43 GMT" } ]
2007-07-09T00:00:00
[ [ "Simon", "Barry", "" ] ]
0705.3641
Nikolay Bobev
Iosif Bena, Nikolay Bobev and Nicholas P. Warner
Bubbles on Manifolds with a U(1) Isometry
33 pages, 5 figures, LaTeX; references added
JHEP 0708:004,2007
10.1088/1126-6708/2007/08/004
SPhT-T07/059
hep-th
null
We investigate the construction of five-dimensional, three-charge supergravity solutions that only have a rotational U(1) isometry. We show that such solutions can be obtained as warped compactifications with a singular ambi-polar hyper-Kahler base space and singular warp factors. We show that the complete solution is regular around the critical surface of the ambi-polar base. We illustrate this by presenting the explicit form of the most general supersymmetric solutions that can be obtained from an Atiyah-Hitchin base space and its ambi-polar generalizations. We make a parallel analysis using an ambi-polar generalization of the Eguchi-Hanson base space metric. We also show how the bubbling procedure applied to the ambi-polar Eguchi-Hanson metric can convert it to a global AdS_2xS^3 compactification.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:51:56 GMT" }, { "version": "v2", "created": "Tue, 19 Jun 2007 01:29:37 GMT" } ]
2009-04-17T00:00:00
[ [ "Bena", "Iosif", "" ], [ "Bobev", "Nikolay", "" ], [ "Warner", "Nicholas P.", "" ] ]
0705.3642
Grant Tremblay
Grant R. Tremblay, Marco Chiaberge, Carlos J. Donzelli, Alice C. Quillen, Alessandro Capetti, William B. Sparks, F. Duccio Macchetto
Isophotal Structure and Dust Distribution in Radio-Loud Elliptical Galaxies
13 pages, 8 figures. Accepted for publication in ApJ
Astrophys.J.666:109-121,2007
10.1086/520333
STScI Eprint #1764
astro-ph
null
We investigate isophotal properties and dust morphology in the nuclear regions of 84 radio galaxies, imaged in the optical and near-infrared as part of Hubble Space Telescope snapshot surveys. We present a sample-wide trend between host galaxy isophotal structure and the inclination of dusty circumnuclear disks at the centers of 13 of these objects. We find that galaxies containing edge-on disks are invariably seen to possess boxy isophotes, while round, face-on disks are seen exclusively in objects with round or elliptical isophotes. Dust-rich sources with disky isophotes are observed only to possess dust in the form of extended filamentary lanes, and not in settled distributions like disks. As we do not expect that edge-on and face-on disks reside in different populations of galaxies, we conclude that perceived isophotal boxiness is dependent upon the angle at which the observer views the host galaxy's axis of symmetry. We discuss our results in the context of dissipative merger scenarios, and infer that dusty disks primarily reside in old, boxy remnants of gas-poor galaxy mergers, whereas filamentary dust lanes reside in younger disky remnants of gas-rich mergers.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:59:53 GMT" } ]
2009-06-23T00:00:00
[ [ "Tremblay", "Grant R.", "" ], [ "Chiaberge", "Marco", "" ], [ "Donzelli", "Carlos J.", "" ], [ "Quillen", "Alice C.", "" ], [ "Capetti", "Alessandro", "" ], [ "Sparks", "William B.", "" ], [ "Macchetto", "F. Duccio", "" ] ]
0705.3643
Hans Kristian Eriksen
H. K. Eriksen, Greg Huey, A. J. Banday, K. M. Gorski, J. B. Jewell, I. J. O'Dwyer, B. D. Wandelt
Bayesian analysis of the low-resolution polarized 3-year WMAP sky maps
5 pages, 4 figures, submitted to ApJL
Astrophys.J.665:L1-L4,2007
10.1086/521191
null
astro-ph
null
We apply a previously developed Gibbs sampling framework to the foreground corrected 3-yr WMAP polarization data and compute the power spectrum and residual foreground template amplitude posterior distributions. We first analyze the co-added Q- and V-band data, and compare our results to the likelihood code published by the WMAP team. We find good agreement, and thus verify the numerics and data processing steps of both approaches. However, we also analyze the Q- and V-bands separately, allowing for non-zero EB cross-correlations and including two individual foreground template amplitudes tracing synchrotron and dust emission. In these analyses, we find tentative evidence of systematics: The foreground tracers correlate with each of the Q- and V-band sky maps individually, although not with the co-added QV map; there is a noticeable negative EB cross-correlation at l <~ 16 in the V-band map; and finally, when relaxing the constraints on EB and BB, noticeable differences are observed between the marginalized band powers in the Q- and V-bands. Further studies of these features are imperative, given the importance of the low-l EE spectrum on the optical depth of reionization tau and the spectral index of scalar perturbations n_s.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:56:16 GMT" } ]
2010-11-11T00:00:00
[ [ "Eriksen", "H. K.", "" ], [ "Huey", "Greg", "" ], [ "Banday", "A. J.", "" ], [ "Gorski", "K. M.", "" ], [ "Jewell", "J. B.", "" ], [ "O'Dwyer", "I. J.", "" ], [ "Wandelt", "B. D.", "" ] ]
0705.3644
Chenguang Lu
Chenguang Lu
Subjective Information Measure and Rate Fidelity Theory
5 pages, 10 figures
null
null
null
cs.IT cs.HC math.IT
null
Using fish-covering model, this paper intuitively explains how to extend Hartley's information formula to the generalized information formula step by step for measuring subjective information: metrical information (such as conveyed by thermometers), sensory information (such as conveyed by color vision), and semantic information (such as conveyed by weather forecasts). The pivotal step is to differentiate condition probability and logical condition probability of a message. The paper illustrates the rationality of the formula, discusses the coherence of the generalized information formula and Popper's knowledge evolution theory. For optimizing data compression, the paper discusses rate-of-limiting-errors and its similarity to complexity-distortion based on Kolmogorov's complexity theory, and improves the rate-distortion theory into the rate-fidelity theory by replacing Shannon's distortion with subjective mutual information. It is proved that both the rate-distortion function and the rate-fidelity function are equivalent to a rate-of-limiting-errors function with a group of fuzzy sets as limiting condition, and can be expressed by a formula of generalized mutual information for lossy coding, or by a formula of generalized entropy for lossless coding. By analyzing the rate-fidelity function related to visual discrimination and digitized bits of pixels of images, the paper concludes that subjective information is less than or equal to objective (Shannon's) information; there is an optimal matching point at which two kinds of information are equal; the matching information increases with visual discrimination (defined by confusing probability) rising; for given visual discrimination, too high resolution of images or too much objective information is wasteful.
[ { "version": "v1", "created": "Thu, 24 May 2007 19:33:43 GMT" } ]
2007-07-13T00:00:00
[ [ "Lu", "Chenguang", "" ] ]
0705.3645
Grzegorz Szamel
Grzegorz Szamel
Dynamics of interacting Brownian particles: a diagrammatic formulation
Minor changes; one reference added; to be published in J. Chem. Phys
null
10.1063/1.2759487
null
cond-mat.soft cond-mat.stat-mech
null
We present a diagrammatic formulation of a theory for the time dependence of density fluctuations in equilibrium systems of interacting Brownian particles. To facilitate derivation of the diagrammatic expansion we introduce a basis that consists of orthogonalized many-particle density fluctuations. We obtain an exact hierarchy of equations of motion for time-dependent correlations of orthogonalized density fluctuations. To simplify this hierarchy we neglect contributions to the vertices from higher-order cluster expansion terms. An iterative solution of the resulting equations can be represented by diagrams with three and four-leg vertices. We analyze the structure of the diagrammatic series for the time-dependent density correlation function and obtain a diagrammatic interpretation of reducible and irreducible memory functions. The one-loop self-consistent approximation for the latter function coincides with mode-coupling approximation for Brownian systems that was derived previously using a projection operator approach.
[ { "version": "v1", "created": "Thu, 24 May 2007 18:59:25 GMT" }, { "version": "v2", "created": "Thu, 21 Jun 2007 17:18:05 GMT" } ]
2009-11-13T00:00:00
[ [ "Szamel", "Grzegorz", "" ] ]
0705.3646
Barry Simon
Dirk Hundertmark and Barry Simon
Eigenvalue bounds in the gaps of Schrodinger operators and Jacobi matrices
null
null
10.1016/j.jmaa.2007.08.059
null
math.SP math-ph math.MP
null
We consider $C=A+B$ where $A$ is selfadjoint with a gap $(a,b)$ in its spectrum and $B$ is (relatively) compact. We prove a general result allowing $B$ of indefinite sign and apply it to obtain a $(\delta V)^{d/2}$ bound for perturbations of suitable periodic Schrodinger operators and a (not quite)Lieb-Thirring bound for perturbations of algebro-geometric almost periodic Jacobi matrices.
[ { "version": "v1", "created": "Thu, 24 May 2007 19:03:23 GMT" } ]
2015-05-13T00:00:00
[ [ "Hundertmark", "Dirk", "" ], [ "Simon", "Barry", "" ] ]
0705.3647
Guangfei Jiang
Guangfei Jiang, C.S. Kochanek
The Baryon Fractions and Mass-to-Light Ratios of Early-Type Galaxies
9 figures
null
10.1086/522580
null
astro-ph
null
We jointly model 22 early-type gravitational lens galaxies with stellar dynamical measurements using standard CDM halo models. The sample is inhomogeneous in both its mass distributions and the evolution of its stellar populations unless the true uncertainties are significantly larger than the reported measurement errors. In general, the individual systems cannot constrain halo models, in the sense that the data poorly constrains the stellar mass fraction of the halo. The ensemble of systems, however, strongly constrains the average stellar mass represented by the visible galaxies to $0.026\pm0.006$ of the halo mass if we neglect adiabatic compression, rising to $0.056\pm0.011$ of the halo mass if we include adiabatic compression. Both estimates are significantly smaller than the global baryon fraction, corresponding to a star formation efficiency for early-type galaxies of $10%-30%$. In the adiabatically compressed models, we find an average local B-band stellar mass-to-light ratio of $(M/L)_0 = (7.2\pm0.5)(M_{\sun}/L_{\sun})$ that evolves by $d\log(M/L)/dz = -0.72\pm0.08$ per unit redshift. Adjusting the isotropy of the stellar orbits has little effect on the results. The adiabatically compressed models are strongly favored if we impose either local estimates of the mass-to-light ratios of early-type galaxies or the weak lensing measurements for the lens galaxies on 100 kpc scales as model constraints.
[ { "version": "v1", "created": "Thu, 24 May 2007 19:17:09 GMT" } ]
2009-11-13T00:00:00
[ [ "Jiang", "Guangfei", "" ], [ "Kochanek", "C. S.", "" ] ]
0705.3648
Benedict von Harling
B. v. Harling, A. Hebecker, T. Noguchi
Energy Transfer between Throats from a 10d Perspective
25 pages; a comment added
JHEP 0711:042,2007
10.1088/1126-6708/2007/11/042
HD-THEP-07-12
hep-th astro-ph gr-qc hep-ph
null
Strongly warped regions, also known as throats, are a common feature of the type IIB string theory landscape. If one of the throats is heated during cosmological evolution, the energy is subsequently transferred to other throats or to massless fields in the unwarped bulk of the Calabi-Yau orientifold. This energy transfer proceeds either by Hawking radiation from the black hole horizon in the heated throat or, at later times, by the decay of throat-localized Kaluza-Klein states. In both cases, we calculate in a 10d setup the energy transfer rate (respectively decay rate) as a function of the AdS scales of the throats and of their relative distance. Compared to existing results based on 5d models, we find a significant suppression of the energy transfer rates if the size of the embedding Calabi-Yau orientifold is much larger than the AdS radii of the throats. This effect can be partially compensated by a small distance between the throats. These results are relevant, e.g., for the analysis of reheating after brane inflation. Our calculation employs the dual gauge theory picture in which each throat is described by a strongly coupled 4d gauge theory, the degrees of freedom of which are localized at a certain position in the compact space.
[ { "version": "v1", "created": "Thu, 24 May 2007 19:45:47 GMT" }, { "version": "v2", "created": "Fri, 28 Mar 2008 15:06:39 GMT" } ]
2009-02-20T00:00:00
[ [ "Harling", "B. v.", "" ], [ "Hebecker", "A.", "" ], [ "Noguchi", "T.", "" ] ]
0705.3649
Qingjuan Yu
Qingjuan Yu, Youjun Lu, D. N. C. Lin
On the origin of kinematic distribution of the sub-parsec young stars in the Galactic center
14 pages, including 13 figures, typo corrected, reference added, ApJ in press
Astrophys.J.666:919-933,2007
10.1086/520622
null
astro-ph
null
Within a half-parsec from the Galactic center (GC), there is a population of coeval young stars which appear to reside in a coherent disk. Surrounding this dynamically-cool stellar system, there is a population of stars with a similar age and much larger eccentricities and inclinations relative to the disk. We propose a hypothesis for the origin of this dynamical dichotomy. Without specifying any specific mechanism, we consider the possibility that both stellar populations were formed within a disk some 6 Myr ago. But this orderly structure was dynamically perturbed outside-in by an intruding object with a mass ~10^4 Msun, which may be an intermediate-mass black hole (IMBH) or a dark stellar cluster hosting an IMBH. We suggest that the perturber migrated inward to ~0.15-0.3pc from the GC under the action of dynamical friction. Along the way, it captured many stars in the outer disk region into its mean-motion resonance, forced them to migrate with it, closely encountered with them, and induced the growth of their eccentricity and inclination. But stars in the inner regions of the disk retain their initial coplanar structure. We predict that some of the inclined and eccentric stars surrounding the disk may have similar Galactocentric semimajor axis. Future precision determination of their kinematic distribution of these stars will not only provide a test for this hypothesis but also evidences for the presence of an IMBH or a dark cluster at the immediate proximity of the massive black hole at the GC. (abridged)
[ { "version": "v1", "created": "Thu, 24 May 2007 19:45:45 GMT" }, { "version": "v2", "created": "Sun, 17 Jun 2007 09:54:14 GMT" } ]
2011-05-12T00:00:00
[ [ "Yu", "Qingjuan", "" ], [ "Lu", "Youjun", "" ], [ "Lin", "D. N. C.", "" ] ]
0705.3650
JoAnne Hewett
Eugene Golowich, JoAnne Hewett, Sandip Pakvasa, Alexey A. Petrov
Implications of D^0-\bar D^0 Mixing for New Physics
86 pages, typos fixed
Phys.Rev.D76:095009,2007
10.1103/PhysRevD.76.095009
SLAC-PUB-12496, WSU-HEP-0701, UH-511-1104-07
hep-ph hep-ex
null
We provide a comprehensive, up-to-date analysis of possible New Physics contributions to the mass difference $\Delta M_D$ in $D^0$-${\bar D}^0$ mixing. We consider the most general low energy effective Hamiltonian and include leading order QCD running of effective operators. We then explore an extensive list of possible New Physics models that can generate these operators, which we organize as including Extra Fermions, Extra Gauge Bosons, Extra Scalars, Extra Space Dimensions and Extra Symmetries. For each model we place restrictions on the allowed parameter space using the recent evidence for observation of $D$ meson mixing. In many scenarios, we find strong constraints that surpass those from other search techniques and provide an important test of flavor changing neutral currents in the up-quark sector. We also review the recent BaBar and Belle findings, and describe the current status of the Standard Model predictions of $D^0$-${\bar D}^0$ mixing.
[ { "version": "v1", "created": "Thu, 24 May 2007 19:47:15 GMT" }, { "version": "v2", "created": "Thu, 13 Sep 2007 19:47:39 GMT" } ]
2008-11-26T00:00:00
[ [ "Golowich", "Eugene", "" ], [ "Hewett", "JoAnne", "" ], [ "Pakvasa", "Sandip", "" ], [ "Petrov", "Alexey A.", "" ] ]
0705.3651
Matthias K\"oppe
Matthias K\"oppe (IMO Magdeburg) and Sven Verdoolaege (LIACS)
Computing parametric rational generating functions with a primal Barvinok algorithm
16 pages, 1 figure; v2: Minor corrections, new example and summary of algorithm; submitted to journal
The Electronic Journal of Combinatorics 15 (2008), #R16
null
null
math.CO
null
Computations with Barvinok's short rational generating functions are traditionally being performed in the dual space, to avoid the combinatorial complexity of inclusion--exclusion formulas for the intersecting proper faces of cones. We prove that, on the level of indicator functions of polyhedra, there is no need for using inclusion--exclusion formulas to account for boundary effects: All linear identities in the space of indicator functions can be purely expressed using half-open variants of the full-dimensional polyhedra in the identity. This gives rise to a practically efficient, parametric Barvinok algorithm in the primal space.
[ { "version": "v1", "created": "Thu, 24 May 2007 19:55:45 GMT" }, { "version": "v2", "created": "Tue, 28 Aug 2007 00:10:21 GMT" } ]
2017-01-03T00:00:00
[ [ "Köppe", "Matthias", "", "IMO Magdeburg" ], [ "Verdoolaege", "Sven", "", "LIACS" ] ]
0705.3652
Alejandro Rodriguez
Alejandro Rodriguez, Marin Soljacic, John D. Joannopoulos and Steven G. Johnson
Chi2 and chi3 harmonic generation at a critical power in inhomogeneous doubly resonant cavities
null
Optics Express, Vol. 15, No. 12, 7303-7318 (2007)
10.1364/OE.15.007303
null
physics.optics
null
We derive general conditions for 100 percent frequency conversion in any doubly resonant nonlinear cavity, for both second- and third-harmonic generation via chi2 and chi3 nonlinearities. We find that conversion efficiency is optimized for a certain critical power depending on the cavity parameters, and assuming reasonable parameters we predict 100 percent conversion using milliwatts of power or less. These results follow from a semi-analytical coupled-mode theory framework which is generalized from previous work to include both chi2 and chi3 media as well as inhomogeneous (fully vectorial) cavities, analyzed in the high-efficiency limit where down-conversion processes lead to a maximum efficiency at the critical power, and which is verified by direct finite-difference time-domain (FDTD) simulations of the nonlinear Maxwell equations. Explicit formulas for the nonlinear coupling coefficients are derived in terms of the linear cavity eigenmodes, which can be used to design and evaluate cavities in arbitrary geometries.
[ { "version": "v1", "created": "Thu, 24 May 2007 20:13:54 GMT" } ]
2011-01-25T00:00:00
[ [ "Rodriguez", "Alejandro", "" ], [ "Soljacic", "Marin", "" ], [ "Joannopoulos", "John D.", "" ], [ "Johnson", "Steven G.", "" ] ]
0705.3653
Zaira Nazario
Zaira Nazario, David I. Santiago
Mott Fermionic "Quantum" Criticality Beyond Ginzburg-Landau-Wilson
null
null
null
null
cond-mat.str-el
null
The Mott critical point between a metal and a correlated insulator has usually been studied via density or spin density bosonic mode fluctuations according to the standard Ginzburg-Landau-Wilson phase transition paradigm. A moment's reflection leads to increasing doubts that such an approach should work as the transition is nonmagnetic, voiding the relevance of spin density modes. Charge density modes are irrelevelant since the long range Coulomb interaction leads to a large plasmon gap and their incompressibility. In solidarity with these doubts, recent measurements of the Mott critical point in low dimensional organic materials yield critical exponents in violent diasagreement with the bosonic mode criticality lore. We propose that fermionic fluctuations control the behavior of the Mott transition. The transition thus has an intrinsic quantum aspect despite being a finite temperature phase transition. We develop this hitherto unexplored physics, obtain experimental predictions and find agreement with one of the novel unexplained experimental exponents. We conclude that this Mott transition corresponds to a new universality class of finite temperature critical points that contains quantum effects and cannot be accounted for by conventional Ginzburg-Landau-Wilson wisdom.
[ { "version": "v1", "created": "Thu, 24 May 2007 20:00:13 GMT" } ]
2011-02-19T00:00:00
[ [ "Nazario", "Zaira", "" ], [ "Santiago", "David I.", "" ] ]
0705.3654
David Roosen
David Roosen, Maarten R. Wegewijs, Walter Hofstetter
Nonequilibrium Dynamics of Anisotropic Large Spins in the Kondo Regime: Time-Dependent Numerical Renormalization Group Analysis
4 pages, 5 figures, published version
Phys.Rev.Lett.100:087201,2008
10.1103/PhysRevLett.100.087201 10.1103/PhysRevLett.105.259901
null
cond-mat.str-el cond-mat.mes-hall
null
We investigate the time-dependent Kondo effect in a single-molecule magnet (SMM) strongly coupled to metallic electrodes. Describing the SMM by a Kondo model with large spin S > 1/2, we analyze the underscreening of the local moment and the effect of anisotropy terms on the relaxation dynamics of the magnetization. Underscreening by single-channel Kondo processes leads to a logarithmically slow relaxation, while finite uniaxial anisotropy causes a saturation of the SMM's magnetization. Additional transverse anisotropy terms induce quantum spin tunneling and a pseudospin-1/2 Kondo effect sensitive to the spin parity.
[ { "version": "v1", "created": "Thu, 24 May 2007 20:00:16 GMT" }, { "version": "v2", "created": "Tue, 11 Mar 2008 17:11:35 GMT" } ]
2011-01-27T00:00:00
[ [ "Roosen", "David", "" ], [ "Wegewijs", "Maarten R.", "" ], [ "Hofstetter", "Walter", "" ] ]
0705.3655
Dan Hooper
Dan Hooper, Douglas P. Finkbeiner and Gregory Dobler
Evidence Of Dark Matter Annihilations In The WMAP Haze
4 pages, 3 figures
Phys.Rev.D76:083012,2007
10.1103/PhysRevD.76.083012
FERMILAB-PUB-07-131-A
astro-ph hep-ph
null
The WMAP experiment has revealed an excess of microwave emission from the region around the center of our Galaxy. It has been suggested that this signal, known as the ``WMAP Haze'', could be synchrotron emission from relativistic electrons and positrons generated in dark matter annihilations. In this letter, we revisit this possibility. We find that the angular distribution of the WMAP Haze matches the prediction for dark matter annihilations with a cusped density profile, $\rho(r) \propto r^{-1.2}$ in the inner kiloparsecs. Comparing the intensity in different WMAP frequency bands, we find that a wide range of possible WIMP annihilation modes are consistent with the spectrum of the haze for a WIMP with a mass in the 100 GeV to multi-TeV range. Most interestingly, we find that to generate the observed intensity of the haze, the dark matter annihilation cross section is required to be approximately equal to the value needed for a thermal relic, $\sigma v \sim 3 \times 10^{-26}$ cm$^3$/s. No boost factors are required. If dark matter annihilations are in fact responsible for the WMAP Haze, and the slope of the halo profile continues into the inner Galaxy, GLAST is expected to detect gamma rays from the dark matter annihilations in the Galactic Center if the WIMP mass is less than several hundred GeV.
[ { "version": "v1", "created": "Thu, 24 May 2007 20:01:04 GMT" } ]
2008-11-26T00:00:00
[ [ "Hooper", "Dan", "" ], [ "Finkbeiner", "Douglas P.", "" ], [ "Dobler", "Gregory", "" ] ]
0705.3656
Robert Finkelstein j
Robert J. Finkelstein
The Elementary Particles as Quantum Knots in Electroweak Theory
29 pages; LaTex file
Int.J.Mod.Phys.A22:4467-4480,2007
10.1142/S0217751X0703707X
UCLA/07/TEP/13
hep-th
null
We explore a knot model of the elementary particles that is compatible with electroweak physics. The knots are quantized and their kinematic states are labelled by $D^j_{mm'}$, irreducible representations of $SU_q(2)$, where j = N/2, m = w/2, m' = (r+1)/2 and (N,w,r) designate respectively the number of crossings, the writhe, and the rotation of the knot. The knot quantum numbers (N,w,r) are related to the standard isotopic spin quantum numbers $(t,t_3,t_0)$ by $(t=N/6,t_3=-w/6,t_0=-(r+1)/6)$, where $t_0$ is the hypercharge. In this model the elementary fermions are low lying states of the quantum trefoil (N=3) and the gauge bosons are ditrefoils (N=6). The fermionic knots interact by the emission and absorption of bosonic knots. In this framework we have explored a slightly modified standard electroweak Lagrangian with a slightly modified gauge group which agrees closely but not entirely with standard electroweak theory.
[ { "version": "v1", "created": "Thu, 24 May 2007 20:05:18 GMT" } ]
2008-11-26T00:00:00
[ [ "Finkelstein", "Robert J.", "" ] ]
0705.3657
B. C. Sanctuary
B. C. Sanctuary
Separation of Bell states
14 pages, no figures, complete re-write of previous submission
null
null
null
physics.gen-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The four Bell states can be represented by separable coherent states which are products of individual non-hermitian spin operators. In the absence of interactions, the non-hermitian states are predicted to form a new quantum state of spin magnitude 1/sqrt(2) rather than 1/2. Properties of these states show that an isolated spin is a resonance state with zero net angular momentum, consistent with a point particle. In addition, the Bell states are shown to take on the identical mathematical form when the two spins are bound (local) or unbound (non-local). The bound Bell states are resonances between four states. When the separate, they do so from only one of its resonance states and their ensemble average defines the unbound Bell states. The bound and unbound Bell states have the same mathematical form due to the persistence of the rotationally invariance of sigma(1)dot sigma(2).
[ { "version": "v1", "created": "Thu, 24 May 2007 20:22:24 GMT" }, { "version": "v2", "created": "Sat, 30 Jun 2007 17:28:08 GMT" }, { "version": "v3", "created": "Mon, 23 Jul 2007 09:05:54 GMT" }, { "version": "v4", "created": "Wed, 10 Oct 2007 02:40:55 GMT" }, { "version": "v5", "created": "Sun, 15 Feb 2009 10:47:49 GMT" } ]
2009-02-15T00:00:00
[ [ "Sanctuary", "B. C.", "" ] ]
0705.3658
James Smith
James P Smith
Picard-Fuchs Differential Equations for Families of K3 Surfaces
Ph.D. Thesis (July 2006). 123 pages, 19 figures
null
null
null
math.AG
null
This thesis studies some examples of families of K3 surfaces with Picard lattices of maximal rank. These families occur as invariants of finite automorphism groups. The Picard-Fuchs differential equations describing the variation of Hodge structure in these families are considered. Techniques are developed to find the corresponding monodromy groups as arithmetic Fuchsian groups acting on the families' period spaces.
[ { "version": "v1", "created": "Thu, 24 May 2007 20:54:17 GMT" } ]
2007-05-28T00:00:00
[ [ "Smith", "James P", "" ] ]
0705.3659
Chi Hin Chan
Chi Hin Chan, Alexis Vasseur
Log improvement of the Prodi-Serrin criteria for Navier-Stokes equations
null
null
null
null
math.AP
null
This article is devoted to a Log improvement of Prodi-Serrin criterion for global regularity to solutions to Navier-Stokes equations in dimension 3. It is shown that the global regualrity holds under the condition that |u|^5/ log (1+|u|) is integrable in space time variables.
[ { "version": "v1", "created": "Thu, 24 May 2007 20:40:30 GMT" } ]
2007-05-28T00:00:00
[ [ "Chan", "Chi Hin", "" ], [ "Vasseur", "Alexis", "" ] ]
0705.3660
Robert Jack
Robert L. Jack, Michael F. Hagan, David Chandler
Fluctuation-dissipation ratios in the dynamics of self-assembly
8 pages, 6 figures
Phys Rev E 76, 021119 (2007)
10.1103/PhysRevE.76.021119
null
cond-mat.stat-mech q-bio.BM
null
We consider two seemingly very different self-assembly processes: formation of viral capsids, and crystallization of sticky discs. At low temperatures, assembly is ineffective, since there are many metastable disordered states, which are a source of kinetic frustration. We use fluctuation-dissipation ratios to extract information about the degree of this frustration. We show that our analysis is a useful indicator of the long term fate of the system, based on the early stages of assembly.
[ { "version": "v1", "created": "Thu, 24 May 2007 20:57:58 GMT" }, { "version": "v2", "created": "Fri, 10 Aug 2007 23:39:01 GMT" } ]
2007-08-22T00:00:00
[ [ "Jack", "Robert L.", "" ], [ "Hagan", "Michael F.", "" ], [ "Chandler", "David", "" ] ]
0705.3661
Alejandro Rodriguez
Alejandro Rodriguez, Mihai Ibanescu, Davide Iannuzzi, J. D. Joannopoulos, and Steven G. Johnson
Virtual photons in imaginary time: Computing exact Casimir forces via standard numerical-electromagnetism techniques
Published in Physical Review A, vol. 76, page 032106 (2007)
null
10.1103/PhysRevA.76.032106
null
quant-ph
null
We describe a numerical method to compute Casimir forces in arbitrary geometries, for arbitrary dielectric and metallic materials, with arbitrary accuracy (given sufficient computational resources). Our approach, based on well-established integration of the mean stress tensor evaluated via the fluctuation-dissipation theorem, is designed to directly exploit fast methods developed for classical computational electromagnetism, since it only involves repeated evaluation of the Green's function for imaginary frequencies (equivalently, real frequencies in imaginary time). We develop the approach by systematically examining various formulations of Casimir forces from the previous decades and evaluating them according to their suitability for numerical computation. We illustrate our approach with a simple finite-difference frequency-domain implementation, test it for known geometries such as a cylinder and a plate, and apply it to new geometries. In particular, we show that a piston-like geometry of two squares sliding between metal walls, in both two and three dimensions with both perfect and realistic metallic materials, exhibits a surprising non-monotonic ``lateral'' force from the walls.
[ { "version": "v1", "created": "Thu, 24 May 2007 21:05:29 GMT" }, { "version": "v2", "created": "Wed, 8 Aug 2007 03:50:46 GMT" }, { "version": "v3", "created": "Wed, 17 Oct 2007 01:48:14 GMT" } ]
2009-11-13T00:00:00
[ [ "Rodriguez", "Alejandro", "" ], [ "Ibanescu", "Mihai", "" ], [ "Iannuzzi", "Davide", "" ], [ "Joannopoulos", "J. D.", "" ], [ "Johnson", "Steven G.", "" ] ]
0705.3662
Frederic Boone
F. Boone, A. J. Baker, E. Schinnerer, F. Combes, S. Garc\'ia-Burillo, R. Neri, L. K. Hunt, S. L\'eon, M. Krips, L. J. Tacconi, A. Eckart
Molecular gas in NUclei of GAlaxies (NUGA) VII. NGC4569, a large scale bar funnelling gas into the nuclear region
accepted for publication in A&A
null
10.1051/0004-6361:20077254
null
astro-ph
null
This work is part of the NUGA survey of CO emission in nearby active galaxies. We present observations of NGC4569, a member of the Virgo Cluster. We analyse the molecular gas distribution and kinematics in the central region and we investigate a possible link to the strong starburst present at the nucleus. 70% of the 1.1x10^9 Msolar of molecular gas detected in the inner 20" is found to be concentrated within the inner 800 pc and is distributed along the large scale stellar bar seen in near-infrared observations. A hole in the CO distribution coincides with the nucleus where most of the Halpha emission and blue light are emitted. The kinematics are modelled in three different ways, ranging from the purely geometrical to the most physical. This approach allows us to constrain progressively the physical properties of the galaxy and eventually to emerge with a reasonable fit to an analytical model of orbits in a barred potential. Fitting an axisymmetric model shows that the non-circular motions must be comparable in amplitude to the circular motions (120 km/s). Fitting a model based on elliptical orbits allows us to identify with confidence the single inner Lindblad resonance (ILR) of the large scale bar. Finally, a model based on analytical solutions for the gas particle orbits in a weakly barred potential constrained by the ILR radius reproduces the observations well. The mass inflow rate is then estimated and discussed based on the best fit model solution. The gravitational torques implied by this model are able to efficiently funnel the gas inside the ILR down to 300 pc, although another mechanism must take over to fuel the nuclear starburst inside 100 pc.
[ { "version": "v1", "created": "Thu, 24 May 2007 23:39:20 GMT" } ]
2009-11-13T00:00:00
[ [ "Boone", "F.", "" ], [ "Baker", "A. J.", "" ], [ "Schinnerer", "E.", "" ], [ "Combes", "F.", "" ], [ "García-Burillo", "S.", "" ], [ "Neri", "R.", "" ], [ "Hunt", "L. K.", "" ], [ "Léon", "S.", "" ], [ "Krips", "M.", "" ], [ "Tacconi", "L. J.", "" ], [ "Eckart", "A.", "" ] ]
0705.3663
Mark Schlossman
Aleksey M. Tikhonov and Mark L. Schlossman
Vaporization and Layering of Alkanols at the Oil/Water Interface
27 pages, 10 figures, to be published in J. Phys. Cond. Mat
null
10.1088/0953-8984/19/37/375101
null
cond-mat.soft
null
This study of adsorption of normal alkanols at the oil/water interface with x-ray reflectivity and tensiometry demonstrates that the liquid to gas monolayer phase transition at the hexane/water interface is thermodynamically favorable only for long-chain alkanols. As the alkanol chain length is decreased, the change in excess interfacial entropy per area decreases to zero. Systems with small values of excess interfacial entropy form multi-molecular layers at the interface instead of the monolayer formed by systems with much larger excess interfacial entropy. Substitution of n-hexane by n-hexadecane significantly alters the interfacial structure for a given alkanol surfactant, but this substitution does not change fundamentally the phase transition behavior of the monolayers. These data show that the critical alkanol carbon number, at which the change in excess interfacial entropy per area decreases to zero, is approximately six carbons larger than the number of carbons in the alkane solvent molecules.
[ { "version": "v1", "created": "Thu, 24 May 2007 21:32:18 GMT" } ]
2009-11-13T00:00:00
[ [ "Tikhonov", "Aleksey M.", "" ], [ "Schlossman", "Mark L.", "" ] ]
0705.3664
Tony Reix
Tony Reix
A LLT-like test for proving the primality of Fermat numbers
11 pages
null
null
null
math.NT math.HO
null
This paper provides a proof of a LLT-like test for Fermat numbers, based on the properties of Lucas Sequences and on the method of Lehmer.
[ { "version": "v1", "created": "Thu, 24 May 2007 21:33:33 GMT" } ]
2007-05-28T00:00:00
[ [ "Reix", "Tony", "" ] ]
0705.3665
Laura Stonehill
J. F. Amsbaugh, J. M. Anaya, J. Banar, T. J. Bowles, M. C. Browne, T. V. Bullard, T. H. Burritt, G. A. Cox-Mobrand, X. Dai, H. Deng, M. Di Marco, P. J. Doe, M. R. Dragowsky, C. A. Duba, F. A. Duncan, E. D. Earle, S. R. Elliott, E.-I. Esch, H. Fergani, J. A. Formaggio, M. M. Fowler, J. E. Franklin, P. Geissb\"uhler, J. V. Germani, A. Goldschmidt, E. Guillian, A. L. Hallin, G. Harper, P. J. Harvey, R. Hazama, K. M. Heeger, J. Heise, A. Hime, M. A. Howe, M. Huang, L. L. Kormos, C. Kraus, C. B. Krauss, J. Law, I. T. Lawson, K. T. Lesko, J. C. Loach, S. Majerus, J. Manor, S. McGee, K. K. S. Miknaitis, G. G. Miller, B. Morissette, A. Myers, N. S. Oblath, H. M. O'Keeffe, R. W. Ollerhead, S. J. M. Peeters, A. W. P. Poon, G. Prior, S. D. Reitzner, K. Rielage, R. G. H. Robertson, P. Skensved, A. R. Smith, M. W. E. Smith, T. D. Steiger, L. C. Stonehill, P. M. Thornewell, N. Tolich, B. A. VanDevender, T. D. Van Wechel, B. L. Wall, H. Wan Chan Tseung, J. Wendland, N. West, J. B. Wilhelmy, J. F. Wilkerson, J. M. Wouters
An array of low-background $^3$He proportional counters for the Sudbury Neutrino Observatory
32 pages, 18 figures, 6 tables
Nucl.Instrum.Meth.A579:1054-1080,2007
10.1016/j.nima.2007.05.321
null
nucl-ex
null
An array of Neutral-Current Detectors (NCDs) has been built in order to make a unique measurement of the total active flux of solar neutrinos in the Sudbury Neutrino Observatory (SNO). Data in the third phase of the SNO experiment were collected between November 2004 and November 2006, after the NCD array was added to improve the neutral-current sensitivity of the SNO detector. This array consisted of 36 strings of proportional counters filled with a mixture of $^3$He and CF$_4$ gas capable of detecting the neutrons liberated by the neutrino-deuteron neutral current reaction in the D$_2$O, and four strings filled with a mixture of $^4$He and CF$_4$ gas for background measurements. The proportional counter diameter is 5 cm. The total deployed array length was 398 m. The SNO NCD array is the lowest-radioactivity large array of proportional counters ever produced. This article describes the design, construction, deployment, and characterization of the NCD array, discusses the electronics and data acquisition system, and considers event signatures and backgrounds.
[ { "version": "v1", "created": "Wed, 23 May 2007 22:19:11 GMT" } ]
2016-08-14T00:00:00
[ [ "Amsbaugh", "J. F.", "" ], [ "Anaya", "J. M.", "" ], [ "Banar", "J.", "" ], [ "Bowles", "T. J.", "" ], [ "Browne", "M. C.", "" ], [ "Bullard", "T. V.", "" ], [ "Burritt", "T. H.", "" ], [ "Cox-Mobrand", "G. A.", "" ], [ "Dai", "X.", "" ], [ "Deng", "H.", "" ], [ "Di Marco", "M.", "" ], [ "Doe", "P. J.", "" ], [ "Dragowsky", "M. R.", "" ], [ "Duba", "C. A.", "" ], [ "Duncan", "F. A.", "" ], [ "Earle", "E. D.", "" ], [ "Elliott", "S. R.", "" ], [ "Esch", "E. -I.", "" ], [ "Fergani", "H.", "" ], [ "Formaggio", "J. A.", "" ], [ "Fowler", "M. M.", "" ], [ "Franklin", "J. E.", "" ], [ "Geissbühler", "P.", "" ], [ "Germani", "J. V.", "" ], [ "Goldschmidt", "A.", "" ], [ "Guillian", "E.", "" ], [ "Hallin", "A. L.", "" ], [ "Harper", "G.", "" ], [ "Harvey", "P. J.", "" ], [ "Hazama", "R.", "" ], [ "Heeger", "K. M.", "" ], [ "Heise", "J.", "" ], [ "Hime", "A.", "" ], [ "Howe", "M. A.", "" ], [ "Huang", "M.", "" ], [ "Kormos", "L. L.", "" ], [ "Kraus", "C.", "" ], [ "Krauss", "C. B.", "" ], [ "Law", "J.", "" ], [ "Lawson", "I. T.", "" ], [ "Lesko", "K. T.", "" ], [ "Loach", "J. C.", "" ], [ "Majerus", "S.", "" ], [ "Manor", "J.", "" ], [ "McGee", "S.", "" ], [ "Miknaitis", "K. K. S.", "" ], [ "Miller", "G. G.", "" ], [ "Morissette", "B.", "" ], [ "Myers", "A.", "" ], [ "Oblath", "N. S.", "" ], [ "O'Keeffe", "H. M.", "" ], [ "Ollerhead", "R. W.", "" ], [ "Peeters", "S. J. M.", "" ], [ "Poon", "A. W. P.", "" ], [ "Prior", "G.", "" ], [ "Reitzner", "S. D.", "" ], [ "Rielage", "K.", "" ], [ "Robertson", "R. G. H.", "" ], [ "Skensved", "P.", "" ], [ "Smith", "A. R.", "" ], [ "Smith", "M. W. E.", "" ], [ "Steiger", "T. D.", "" ], [ "Stonehill", "L. C.", "" ], [ "Thornewell", "P. M.", "" ], [ "Tolich", "N.", "" ], [ "VanDevender", "B. A.", "" ], [ "Van Wechel", "T. D.", "" ], [ "Wall", "B. L.", "" ], [ "Tseung", "H. Wan Chan", "" ], [ "Wendland", "J.", "" ], [ "West", "N.", "" ], [ "Wilhelmy", "J. B.", "" ], [ "Wilkerson", "J. F.", "" ], [ "Wouters", "J. M.", "" ] ]
0705.3666
Michael Henry
Michael K. Henry, Alexey V. Gorshkov, Yaakov S. Weinstein, Paola Cappellaro, Joseph Emerson, Nicolas Boulant, Jonathan S. Hodges, Chandrasekhar Ramanathan, Timothy F. Havel, Rudy Martinez, and David G. Cory
Signatures of incoherence in a quantum information processor
15 pages, 6 figures
null
null
null
quant-ph
null
Incoherent noise is manifest in measurements of expectation values when the underlying ensemble evolves under a classical distribution of unitary processes. While many incoherent processes appear decoherent, there are important differences. The distribution functions underlying incoherent processes are either static or slowly varying with respect to control operations and so the errors introduced by these distributions are refocusable. The observation and control of incoherence in small Hilbert spaces is well known. Here we explore incoherence during an entangling operation, such as is relevant in quantum information processing. As expected, it is more difficult to separate incoherence and decoherence over such processes. However, by studying the fidelity decay under a cyclic entangling map we are able to identify distinctive experimental signatures of incoherence. This result is demonstrated both through numerical simulations and experimentally in a three qubit nuclear magnetic resonance implementation.
[ { "version": "v1", "created": "Thu, 24 May 2007 21:40:08 GMT" }, { "version": "v2", "created": "Tue, 21 Aug 2007 02:46:44 GMT" } ]
2007-08-21T00:00:00
[ [ "Henry", "Michael K.", "" ], [ "Gorshkov", "Alexey V.", "" ], [ "Weinstein", "Yaakov S.", "" ], [ "Cappellaro", "Paola", "" ], [ "Emerson", "Joseph", "" ], [ "Boulant", "Nicolas", "" ], [ "Hodges", "Jonathan S.", "" ], [ "Ramanathan", "Chandrasekhar", "" ], [ "Havel", "Timothy F.", "" ], [ "Martinez", "Rudy", "" ], [ "Cory", "David G.", "" ] ]
0705.3667
Natasa Sesum
Panagiota Daskalopoulos, Natasa Sesum
Classification of singularities in the complete conformally flat Yamabe flow
The paper has been withdrawn due to a crucial error in the argument
null
null
null
math.DG
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We show that an eternal solution to a complete, locally conformally flat Yamabe flow, $\frac{\partial}{\partial t} g = -Rg$, with uniformly bounded scalar curvature and positive Ricci curvature at $t = 0$, where the scalar curvature assumes its maximum is a gradient steady soliton. As an application of that, we study the blow up behavior of $g(t)$ at the maximal time of existence, $T < \infty$. We assume that $(M,g(\cdot, t))$ satisfies (i) the injectivity radius bound {\bf or} (ii) the Schouten tensor is positive at time $t = 0$ and the scalar curvature bounded at each time-slice. We show that the singularity the flow develops at time $T$ is always of type I.
[ { "version": "v1", "created": "Thu, 24 May 2007 21:40:09 GMT" }, { "version": "v2", "created": "Fri, 6 Feb 2009 19:32:39 GMT" }, { "version": "v3", "created": "Fri, 8 Oct 2010 13:29:05 GMT" }, { "version": "v4", "created": "Mon, 5 Mar 2012 15:59:57 GMT" } ]
2012-03-06T00:00:00
[ [ "Daskalopoulos", "Panagiota", "" ], [ "Sesum", "Natasa", "" ] ]
0705.3668
Arne Rau
S. R. Kulkarni, E. O. Ofek, A. Rau, S. B. Cenko, A. M. Soderberg, D. B. Fox, A. Gal-Yam, P. L. Capak, D. S. Moon, W. Li, A. V. Filippenko, E. Egami, J. Kartaltepe, D. B. Sanders
An unusually brilliant transient in the galaxy Messier 85
10 pages, 4 figures. Appeared in Nature May 24. Supplementary information available at http://www.nature.com/nature
Nature 447:458-460,2007
10.1038/nature05822
null
astro-ph
null
Historically, variable and transient sources have both surprised astronomers and provided new views of the heavens. Here we report the discovery of an optical transient in the outskirts of the lenticular galaxy Messier 85 in the Virgo Cluster. With a peak absolute R magnitude of -12 this event is distinctly brighter than novae, but fainter than type Ia supernovae (expected from a population of old stars in lenticular galaxies). Archival images of the field do not show a luminous star at that position with an upper limit of ~-4.1, so it is unlikely to be a giant eruption from a luminous blue variable star. Over a two month period the transient emitted radiation energy of almost 10E47 erg and subsequently faded in the opical sky. It is similar to, but more luminous at peak by a factor of 6 than, an enigmatic transient in the galaxy M31. A possible origin of M85 OT2006-1 is a stellar merger. If so, searches for similar events in nearby galaxies will not only allow to study the physics of hyper-Eddington sources, but also probe an important phase in the evolution of stellar binary systems.
[ { "version": "v1", "created": "Thu, 24 May 2007 21:46:56 GMT" } ]
2010-05-12T00:00:00
[ [ "Kulkarni", "S. R.", "" ], [ "Ofek", "E. O.", "" ], [ "Rau", "A.", "" ], [ "Cenko", "S. B.", "" ], [ "Soderberg", "A. M.", "" ], [ "Fox", "D. B.", "" ], [ "Gal-Yam", "A.", "" ], [ "Capak", "P. L.", "" ], [ "Moon", "D. S.", "" ], [ "Li", "W.", "" ], [ "Filippenko", "A. V.", "" ], [ "Egami", "E.", "" ], [ "Kartaltepe", "J.", "" ], [ "Sanders", "D. B.", "" ] ]
0705.3669
Donald Sofge
Donald A. Sofge
Structural Health Monitoring Using Neural Network Based Vibrational System Identification
4 pages
D. Sofge, "Structural Health Monitoring Using Neural Network Based Vibrational System Identification," In Proceedings of the Australia-New Zealand Conference on Intelligent Information Systems, pp. 91-94, IEEE, 1994
10.1109/ANZIIS.1994.396943
null
cs.NE cs.CV cs.SD
null
Composite fabrication technologies now provide the means for producing high-strength, low-weight panels, plates, spars and other structural components which use embedded fiber optic sensors and piezoelectric transducers. These materials, often referred to as smart structures, make it possible to sense internal characteristics, such as delaminations or structural degradation. In this effort we use neural network based techniques for modeling and analyzing dynamic structural information for recognizing structural defects. This yields an adaptable system which gives a measure of structural integrity for composite structures.
[ { "version": "v1", "created": "Thu, 24 May 2007 21:48:18 GMT" } ]
2016-11-17T00:00:00
[ [ "Sofge", "Donald A.", "" ] ]
0705.3670
Yaroslav Kartashov
Yaroslav V. Kartashov, Boris A. Malomed, Lluis Torner
Guiding-center solitons in rotating potentials
16 pages, 6 figures, to appear in Physical Review A
Physical Review A 75, 061602(R) (2007)
10.1103/PhysRevA.75.061602
null
physics.optics nlin.PS
null
We demonstrate that rotating quasi-one-dimensional potentials, periodic or parabolic, support solitons in settings where they are otherwise impossible. Ground-state and vortex solitons are found in defocusing media, if the rotation frequency exceeds a critical value. The revolving periodic potentials exhibit the strongest stabilization capacity at a finite optimum value of their strength, while the rotating parabolic trap features a very sharp transition to stability with the increase of rotation frequency.
[ { "version": "v1", "created": "Thu, 24 May 2007 21:58:34 GMT" } ]
2009-11-13T00:00:00
[ [ "Kartashov", "Yaroslav V.", "" ], [ "Malomed", "Boris A.", "" ], [ "Torner", "Lluis", "" ] ]
0705.3671
Guglielmo Fucci
Guglielmo Fucci, Bixiang Wang, Preeti Singh
Asymptotic Behavior of the Newton-Boussinesq Equation in a Two-Dimensional Channel
null
Nonlinear Analysis, 70 (2009) 2000-2013
10.1016/j.na.2008.02.098
null
math-ph math.MP
null
We prove the existence of a global attractor for the Newton-Boussinesq equation defined in a two-dimensional channel. The asymptotic compactness of the equation is derived by the uniform estimates on the tails of solutions. We also establish the regularity of the global attractor.
[ { "version": "v1", "created": "Thu, 24 May 2007 22:04:04 GMT" } ]
2009-01-08T00:00:00
[ [ "Fucci", "Guglielmo", "" ], [ "Wang", "Bixiang", "" ], [ "Singh", "Preeti", "" ] ]
0705.3672
Gregory Soyez
G. Soyez
Saturation QCD predictions with heavy quarks at HERA
8 pages, 5 figures
Phys.Lett.B655:32-38,2007
10.1016/j.physletb.2007.07.076
null
hep-ph
null
The measurement of the proton structure function at HERA is often seen as a hint for the observation of saturation in high-energy QCD e.g. through the observation of geometric scaling. Accordingly, the dipole picture provides a powerful framework in which the QCD-based saturation models can be confronted to the data. In this paper, we give a parametrisation of proton structure function which is directly constrained by the dynamics of QCD in its high-energy limit and fully includes the heavy quark effects. We obtain a good agreement with the available data. Furthermore, to the contrary of various models in the literature, we do not observe a significant decrease of the saturation momentum due to the heavy quark inclusion.
[ { "version": "v1", "created": "Thu, 24 May 2007 22:05:43 GMT" } ]
2008-11-26T00:00:00
[ [ "Soyez", "G.", "" ] ]
0705.3673
Lotfi Hermi
Evans M. Harrell II and Lotfi Hermi
Differential inequalities for Riesz means and Weyl-type bounds for eigenvalues
21 pages, 3 figures
null
null
null
math.SP math-ph math.MP
null
We derive differential inequalities and difference inequalities for Riesz means of eigenvalues of the Dirichlet Laplacian, R_{\sigma}(z) := \sum_k{(z -\lambda_k)_+^{\sigma}}. Here ${\lambda_k}_{k=1}^{\infty}$ are the ordered eigenvalues of the Laplacian on a bounded domain $\Omega \subset \R^d$, and $x_+ := \max(0, x)$ denotes the positive part of the quantity $x$. As corollaries of these inequalities, we derive Weyl-type bounds on $\lambda_k$, on averages such as $\bar{\lambda_k} := {\frac 1 k}\sum_{\ell \le k}\lambda_\ell$, and on the eigenvalue counting function. For example, we prove that for all domains and all $k \ge j \frac{1+\frac d 2}{1+\frac d 4}$, {\bar{\lambda_{k}}}/{\bar{\lambda_{j}}} \le 2 (\frac{1+\frac d 4}{1+\frac d 2})^{1+\frac 2 d}({\frac k j})^{\frac 2 d}.
[ { "version": "v1", "created": "Thu, 24 May 2007 22:11:39 GMT" } ]
2007-05-28T00:00:00
[ [ "Harrell", "Evans M.", "II" ], [ "Hermi", "Lotfi", "" ] ]
0705.3674
Delfim F. M. Torres
Moulay Rchid Sidi Ammi, Delfim F. M. Torres
Existence of Infinitely Many Solutions for a Quasilinear Elliptic Problem on Time Scales
9 pages
International Journal of Pure and Applied Mathematics, Vol.39, No.2, 2007, pp. 239--248
null
null
math.AP
null
We study a boundary-value quasilinear elliptic problem on a generic time scale. Making use of the fixed-point index theory, sufficient conditions are given to obtain existence, multiplicity, and infinite solvability of positive solutions.
[ { "version": "v1", "created": "Thu, 24 May 2007 22:19:53 GMT" } ]
2007-10-08T00:00:00
[ [ "Ammi", "Moulay Rchid Sidi", "" ], [ "Torres", "Delfim F. M.", "" ] ]
0705.3675
Hiroki Wadati
Y.-H. Lin, K. Terai, H. Wadati, M. Kobayashi, M. Takizawa, J. I. Hwang, A. Fujimori, C.-W. Nan, J.-F. Li, S.-I. Fujimori, T. Okane, Y. Saitoh, K. Kobayashi
Phase Change Observed in Ultrathin Ba0.5Sr0.5TiO3 Films by in-situ Resonant Photoemission Spectroscopy
13 pages, 4 figures
Appl. Phys. Lett. 90, 222909 (2007)
10.1063/1.2745249
null
cond-mat.mtrl-sci
null
Epitaxial Ba0.5Sr0.5TiO3 thin films were prepared on Nb-doped SrTiO3 (100)substrates by the pulsed laser deposition technique, and were studied by measuring the Ti 2p - 3d resonant photoemission spectra in the valence-band region as a function of film thickness, both at room temperature and low temperature. Our results demonstrated an abrupt variation in the spectral structures between 2.8 nm (~7 monolayers) and 2.0 nm (~5 monolayers) Ba0.5Sr0.5TiO3 films, suggesting that there exists a critical thickness for phase change in the range of 2.0 nm to 2.8 nm. This may be ascribed mainly to the intrinsic size effects.
[ { "version": "v1", "created": "Thu, 24 May 2007 22:50:41 GMT" } ]
2007-06-13T00:00:00
[ [ "Lin", "Y. -H.", "" ], [ "Terai", "K.", "" ], [ "Wadati", "H.", "" ], [ "Kobayashi", "M.", "" ], [ "Takizawa", "M.", "" ], [ "Hwang", "J. I.", "" ], [ "Fujimori", "A.", "" ], [ "Nan", "C. -W.", "" ], [ "Li", "J. -F.", "" ], [ "Fujimori", "S. -I.", "" ], [ "Okane", "T.", "" ], [ "Saitoh", "Y.", "" ], [ "Kobayashi", "K.", "" ] ]
0705.3676
Hamad Yehia
H.M. Yehia
Atlas of two-dimensional irreversible conservative lagrangian mechanical systems with a second quadratic integral
Paper to be published in "Journal of Mathematical Physics", Vol. 48, issue 7, July 2007
null
10.1063/1.2748374
null
nlin.SI
null
This paper aims at the most comprehensive and systematic construction and tabulation of mechanical systems that admit a second invariant, quadratic in velocities, other than the Hamiltonian. The configuration space is in general a 2D Riemannian or pseudo-Riemannian manifold and the determination of its geometry is a part of the process of solution. Forces acting on the system include a part derived from a scalar potential and a part derived from a vector potential, associated with terms linear in velocities in the Lagrangian function of the system. The last cause time-irreversibility of the system. We construct 41 multi-parameter integrable systems of the type described in the title mostly on Riemannian manifolds. They are mostly new and cover all previously known systems as special cases, corresponding to special values of the parameters. Those include all known cases of motion of a particle in the plane and all known cases in the dynamics of rigid body. In the last field we introduce a new integrable case related to Steklov's case of motion of a body in a liquid. Several new cases of motion in the plane, on the sphere and on the pseudo-sphere or in the hyperbolic plane are found as special cases. Prospective applications in mathematics and physics are also pointed out.
[ { "version": "v1", "created": "Thu, 24 May 2007 23:03:38 GMT" } ]
2009-11-13T00:00:00
[ [ "Yehia", "H. M.", "" ] ]
0705.3677
Cemal Akcaba
Cemal Ak\c{c}aba, Patrick Kuppinger and Helmut B\"olcskei
Distributed Transmit Diversity in Relay Networks
5 pages, 1 figure
null
null
null
cs.IT math.IT
null
We analyze fading relay networks, where a single-antenna source-destination terminal pair communicates through a set of half-duplex single-antenna relays using a two-hop protocol with linear processing at the relay level. A family of relaying schemes is presented which achieves the entire optimal diversity-multiplexing (DM) tradeoff curve. As a byproduct of our analysis, it follows that delay diversity and phase-rolling at the relay level are optimal with respect to the entire DM-tradeoff curve, provided the delays and the modulation frequencies, respectively, are chosen appropriately.
[ { "version": "v1", "created": "Thu, 24 May 2007 23:07:56 GMT" } ]
2016-08-14T00:00:00
[ [ "Akçaba", "Cemal", "" ], [ "Kuppinger", "Patrick", "" ], [ "Bölcskei", "Helmut", "" ] ]
0705.3678
Luc Dessart
Luc Dessart, Adam Burrows, Eli Livne, and Christian Ott
Magnetically-driven explosions of rapidly-rotating white dwarfs following Accretion-Induced Collapse
16 pages, 8 figures, paper accepted to ApJ; High resolution version available at http://hermes.as.arizona.edu/~luc/aic_mhd/aic_mhd.html
null
10.1086/521701
null
astro-ph
null
We present 2D multi-group flux-limited diffusion magnetohydrodynamics (MHD) simulations of the Accretion-Induced Collapse (AIC) of a rapidly-rotating white dwarf. We focus on the dynamical role of MHD processes after the formation of a millisecond-period protoneutron star. We find that including magnetic fields and stresses can lead to a powerful explosion with an energy of a few Bethe, rather than a weak one of at most 0.1 Bethe, with an associated ejecta mass of ~0.1Msun, instead of a few 0.001Msun. The core is spun down by ~30% within 500ms after bounce, and the rotational energy extracted from the core is channeled into magnetic energy that generates a strong magnetically-driven wind, rather than a weak neutrino-driven wind. Baryon loading of the ejecta, while this wind prevails, precludes it from becoming relativistic. This suggests that a GRB is not expected to emerge from such AICs during the early protoneutron star phase, except in the unlikely event that the massive white dwarf has sufficient mass to lead to black hole formation. In addition, we predict both negligible 56Ni-production (that should result in an optically-dark, adiabatically-cooled explosion) and the ejection of 0.1Msun of material with an electron fraction of 0.1-0.2. Such pollution by neutron-rich nuclei puts strong constraints on the possible rate of such AICs. Moreover, being free from ``fallback,'' such highly-magnetized millisecond-period protoneutron stars may later become magnetars, and the magnetically-driven winds may later transition to Poynting-flux-dominated, relativistic winds, eventually detectable as GRBs at cosmological distances. However, the low expected event rate of AICs will constrain them to be, at best, a small subset of GRB and/or magnetar progenitors.
[ { "version": "v1", "created": "Thu, 24 May 2007 23:17:50 GMT" }, { "version": "v2", "created": "Thu, 2 Aug 2007 16:23:16 GMT" } ]
2009-11-13T00:00:00
[ [ "Dessart", "Luc", "" ], [ "Burrows", "Adam", "" ], [ "Livne", "Eli", "" ], [ "Ott", "Christian", "" ] ]
0705.3679
Yong Chen
Yong Chen, Pan Zhang, Lianchun Yu, and Shengli Zhang
Transient dynamics for sequence processing neural networks: effect of degree distributions
11 pages, 6 figures
Phys. Rev. E 77, 016110 (2008)
10.1103/PhysRevE.77.016110
null
cond-mat.dis-nn cond-mat.stat-mech
null
We derive a analytic evolution equation for overlap parameters including the effect of degree distribution on the transient dynamics of sequence processing neural networks. In the special case of globally coupled networks, the precisely retrieved critical loading ratio $\alpha_c = N ^{-1/2}$ is obtained, where $N$ is the network size. In the presence of random networks, our theoretical predictions agree quantitatively with the numerical experiments for delta, binomial, and power-law degree distributions.
[ { "version": "v1", "created": "Thu, 24 May 2007 23:55:34 GMT" }, { "version": "v2", "created": "Thu, 31 Jan 2008 04:18:42 GMT" } ]
2008-01-31T00:00:00
[ [ "Chen", "Yong", "" ], [ "Zhang", "Pan", "" ], [ "Yu", "Lianchun", "" ], [ "Zhang", "Shengli", "" ] ]
0705.3680
Jorge Quintanilla
Vivaldo L. Campo Jr., Klaus Capelle, Jorge Quintanilla and Chris Hooley
Quantitative determination of the Hubbard model phase diagram from optical lattice experiments by two-parameter scaling
Improved version with new plots and additional discussions; 4 pages, 3 figures; Phys. Rev. Lett. (accepted)
Phys. Rev. Lett. 99, 240403 (2007)
10.1103/PhysRevLett.99.240403
null
cond-mat.other cond-mat.str-el
null
We propose an experiment to obtain the phase diagram of the fermionic Hubbard model, for any dimensionality, using cold atoms in optical lattices. It is based on measuring the total energy for a sequence of trap profiles. It combines finite-size scaling with an additional `finite-curvature scaling' necessary to reach the homogeneous limit. We illustrate its viability in the 1D case, simulating experimental data in the Bethe-Ansatz local density approximation. Including experimental errors, the filling corresponding to the Mott transition can be determined with better than 3% accuracy.
[ { "version": "v1", "created": "Fri, 25 May 2007 00:05:29 GMT" }, { "version": "v2", "created": "Thu, 25 Oct 2007 17:13:15 GMT" } ]
2007-12-13T00:00:00
[ [ "Campo", "Vivaldo L.", "Jr." ], [ "Capelle", "Klaus", "" ], [ "Quintanilla", "Jorge", "" ], [ "Hooley", "Chris", "" ] ]
0705.3681
Leigh Jenkins
L.P. Jenkins (GSFC), A.E. Hornschemeier (GSFC), B. Mobasher (STScI), D.M. Alexander (Univ. of Durham), F.E. Bauer (Columbia)
Uncovering the Near-IR Dwarf Galaxy Population of the Coma Cluster with Spitzer IRAC
18 pages, 15 figures. Accepted for publication in ApJ. Typos corrected and minor updates to Table 4/Fig.15 to match proofed version
Astrophys.J.666:846-862,2007
10.1086/520035
null
astro-ph
null
We present the first results of a Spitzer IRAC (Infrared Array Camera) wide-field survey of the Coma cluster. The observations cover two fields of different galaxy densities; the first is a 0.733 deg^2 region in the core of the cluster (Coma 1), the second a 0.555 deg^2 off-center region located ~57 arcmin (1.7 Mpc) south-west from the core (Coma 3). The observations, although short 70-90 s exposures, are very sensitive; we detect ~29,200 sources at 3.6 micron over the total ~1.3 deg^2 survey area. We construct 3.6 micron galaxy luminosity functions (LFs) for each field using selection functions based on spectroscopic redshifts. At the bright end, the LFs are well modeled by a traditional Schechter function; [M^star (3.6 micron), alpha_1] = [-25.17, -1.18] and [-24.69, -1.30] for Coma 1 and Coma 3 respectively. However, at the faint end (M(3.6 micron) > -20.5), there is a steep increase in the LF slope in both fields indicative of large numbers of red dwarf galaxies. The reality of this population is examined using optical counterparts in SDSS data with optical color filtering (g-r<1.3). The steep increase can be modeled with a power-law function, with slopes of alpha_2 = -2.18 (Coma 1) and alpha_2 = -2.60 (Coma 3). A qualitative comparison with optical (B- and R-band) LFs shows that we are likely to be observing a larger population of dwarf galaxies in the near-IR, which may be a low-surface-brightness (LSB) population that IRAC is particularly sensitive to, or a population too red to be detected in existing optical surveys down to R~20.
[ { "version": "v1", "created": "Fri, 25 May 2007 01:11:27 GMT" }, { "version": "v2", "created": "Fri, 3 Aug 2007 21:03:18 GMT" } ]
2009-06-23T00:00:00
[ [ "Jenkins", "L. P.", "", "GSFC" ], [ "Hornschemeier", "A. E.", "", "GSFC" ], [ "Mobasher", "B.", "", "STScI" ], [ "Alexander", "D. M.", "", "Univ. of Durham" ], [ "Bauer", "F. E.", "", "Columbia" ] ]
0705.3682
Azusa Minamizaki
Azusa Minamizaki and Akio Sugamoto
Can the Baryon Number Density and the Cosmological Constant be interrelated?
13pages, Added references, corrected typos, some changes to abstract and discussion, version to appear in PLB
Phys.Lett.B659:656-660,2008
10.1016/j.physletb.2007.11.052
OCHA-PP-272
hep-ph
null
A toy model is proposed in which the cosmological constant and the baryon number density of the universe are interrelated. The model combines the mechanism of Dimopoulos and Susskind in which the baryon number density of the universe is generated by the time-dependence of the phase of a complex scalar field, i.e. its `angular momentum' in the two-dimensinal complex field space, with that of Yoshimura in which the `centrifugal force' due the `angular momentum' pushes the vacuum expectation value of the scalar field out of a negative potential minimum and provides a small but positive cosmological constant. Unfortunately, our model fails to relate the smallness of the two numbers directly, requiring a fine-tuning of the negative potential minimum.
[ { "version": "v1", "created": "Fri, 25 May 2007 02:15:30 GMT" }, { "version": "v2", "created": "Mon, 28 Jan 2008 12:43:39 GMT" } ]
2008-11-26T00:00:00
[ [ "Minamizaki", "Azusa", "" ], [ "Sugamoto", "Akio", "" ] ]
0705.3683
Hung-Ta Pai
H.-T. Pai and Y. S. Han
Power-Efficient Direct-Voting Assurance for Data Fusion in Wireless Sensor Networks
33 pages, 7 figures, 2 tables
null
null
null
cs.CR cs.DC cs.NI
null
Wireless sensor networks place sensors into an area to collect data and send them back to a base station. Data fusion, which fuses the collected data before they are sent to the base station, is usually implemented over the network. Since the sensor is typically placed in locations accessible to malicious attackers, information assurance of the data fusion process is very important. A witness-based approach has been proposed to validate the fusion data. In this approach, the base station receives the fusion data and "votes" on the data from a randomly chosen sensor node. The vote comes from other sensor nodes, called "witnesses," to verify the correctness of the fusion data. Because the base station obtains the vote through the chosen node, the chosen node could forge the vote if it is compromised. Thus, the witness node must encrypt the vote to prevent this forgery. Compared with the vote, the encryption requires more bits, increasing transmission burden from the chosen node to the base station. The chosen node consumes more power. This work improves the witness-based approach using direct voting mechanism such that the proposed scheme has better performance in terms of assurance, overhead, and delay. The witness node transmits the vote directly to the base station. Forgery is not a problem in this scheme. Moreover, fewer bits are necessary to represent the vote, significantly reducing the power consumption. Performance analysis and simulation results indicate that the proposed approach can achieve a 40 times better overhead than the witness-based approach.
[ { "version": "v1", "created": "Fri, 25 May 2007 02:56:47 GMT" } ]
2007-05-28T00:00:00
[ [ "Pai", "H. -T.", "" ], [ "Han", "Y. S.", "" ] ]
0705.3684
Ji-hyun Kang
Ji-hyun Kang, Bon-Chul Koo
Faint HI 21-cm Emission Line Wings at Forbidden-Velocities
41 pages, 14 figures, to be published in apjs
null
10.1086/519769
null
astro-ph
null
We present the results of a search for faint HI 21-cm emission line wings at velocities forbidden by Galactic rotation in the Galactic plane using the Leiden/Dwingeloo HI Survey data and the HI Southern Galactic Plane Survey data. These ``forbidden-velocity wings (FVWs)'' appear as protruding excessive emission in comparison with their surroundings in limited (< 2 deg) spatial regions over velocity extent more than ~20 km/s in large-scale (l-v) diagrams. Their high-velocities imply that there should be some dynamical phenomena associated. We have identified 87 FVWs. We present their catalog, and discuss their distribution and statistical properties. We found that 85% of FVWs are not coincident with known supernova remnants (SNRs), galaxies, or high-velocity clouds. Their natures are currently unknown. We suspect that many of them are fast-moving HI shells and filaments associated with the oldest SNRs that are essentially invisible except via their HI line emission. We discuss other possible origins.
[ { "version": "v1", "created": "Fri, 25 May 2007 03:20:06 GMT" } ]
2009-11-13T00:00:00
[ [ "Kang", "Ji-hyun", "" ], [ "Koo", "Bon-Chul", "" ] ]
0705.3685
Zeqian Chen
Zeqian Chen
Dirichlet problems for stationary von Neumann-Landau wave equations
9 pages
null
null
null
math-ph math.MP
null
It is known that von Neumann-Landau wave equation can present a mathematical formalism of motion of quantum mechanics, that is an extension of Schr\"{o}dinger's wave equation. In this paper, we concern with the Dirichlet problem of the stationary von Neumann-Landau wave equation: {(- \triangle_x + \triangle_y) \Phi (x, y) = 0, x, y \in \Omega, \Phi|_{\partial \Omega \times \partial \Omega} = f, where $\Omega$ is a bounded domain in $\mathbf{R}^n.$ By introducing anti-inner product spaces, we show the existence and uniqueness of the generalized solution for the above Dirichlet problem by functional-analytic methods.
[ { "version": "v1", "created": "Fri, 25 May 2007 03:42:59 GMT" } ]
2007-05-28T00:00:00
[ [ "Chen", "Zeqian", "" ] ]
0705.3686
Ryuichiro Kitano
Masahiro Ibe, Ryuichiro Kitano
Sweet Spot Supersymmetry
53 pages, 14 figures, 2 tables
JHEP 0708:016,2007
10.1088/1126-6708/2007/08/016
SLAC-PUB-12532
hep-ph
null
We find that there is no supersymmetric flavor/CP problem, mu-problem, cosmological moduli/gravitino problem or dimension four/five proton decay problem in a class of supersymmetric theories with O(1) GeV gravitino mass. The cosmic abundance of the non-thermally produced gravitinos naturally explains the dark matter component of the universe. A mild hierarchy between the mass scale of supersymmetric particles and electroweak scale is predicted, consistent with the null result of a search for the Higgs boson at the LEP-II experiments. A relation to the strong CP problem is addressed. We propose a parametrization of the model for the purpose of collider studies. The scalar tau lepton is the next to lightest supersymmetric particle in a theoretically favored region of the parameter space. The lifetime of the scalar tau is of O(1000) seconds with which it is regarded as a charged stable particle in collider experiments. We discuss characteristic signatures and a strategy for confirmation of this class of theories at the LHC experiments.
[ { "version": "v1", "created": "Fri, 25 May 2007 03:51:02 GMT" } ]
2009-04-21T00:00:00
[ [ "Ibe", "Masahiro", "" ], [ "Kitano", "Ryuichiro", "" ] ]
0705.3687
Angelle Tanner
Angelle Tanner, Charles Beichman, Rachel Akeson, Andrea Ghez, Konstantin N. Grankin, William Herbst, Lynne Hillenbrand, Marcos Huerta, Quinn Konopacky, Stanimir Metchev, Subhanjoy Mohanty, L. Prato, Michal Simon
SIM PlanetQuest Key Project Precursor Observations to Detect Gas Giant Planets Around Young Stars
Accepted for publication in Publications of the Astronomical Society of the Pacific, 25 pages, 9 figures
null
10.1086/520774
null
astro-ph
null
We present a review of precursor observing programs for the SIM PlanetQuest Key project devoted to detecting Jupiter mass planets around young stars. In order to ensure that the stars in the sample are free of various sources of astrometric noise that might impede the detection of planets, we have initiated programs to collect photometry, high contrast images, interferometric data and radial velocities for stars in both the Northern and Southern hemispheres. We have completed a high contrast imaging survey of target stars in Taurus and the Pleiades and found no definitive common proper motion companions within one arcsecond (140 AU) of the SIM targets. Our radial velocity surveys have shown that many of the target stars in Sco-Cen are fast rotators and a few stars in Taurus and the Pleiades may have sub-stellar companions. Interferometric data of a few stars in Taurus show no signs of stellar or sub-stellar companions with separations of <5 mas. The photometric survey suggests that approximately half of the stars initially selected for this program are variable to a degree (1 sigma>0.1 mag) that would degrade the astrometric accuracy achievable for that star. While the precursor programs are still a work in progress, we provide a comprehensive list of all targets ranked according to their viability as a result of the observations taken to date. By far, the observable that moves the most targets from the SIM-YSO program is photometric variability.
[ { "version": "v1", "created": "Fri, 25 May 2007 03:57:34 GMT" } ]
2016-08-14T00:00:00
[ [ "Tanner", "Angelle", "" ], [ "Beichman", "Charles", "" ], [ "Akeson", "Rachel", "" ], [ "Ghez", "Andrea", "" ], [ "Grankin", "Konstantin N.", "" ], [ "Herbst", "William", "" ], [ "Hillenbrand", "Lynne", "" ], [ "Huerta", "Marcos", "" ], [ "Konopacky", "Quinn", "" ], [ "Metchev", "Stanimir", "" ], [ "Mohanty", "Subhanjoy", "" ], [ "Prato", "L.", "" ], [ "Simon", "Michal", "" ] ]
0705.3688
Thomas Gorin
G. V. L\'opez, T. Gorin, and L. Lara
Quantum computation in a Ising spin chain taking into account second neighbor couplings
19 pages, 6 figures
null
10.1007/s10773-007-9607-8
null
quant-ph
null
We consider the realization of a quantum computer in a chain of nuclear spins coupled by an Ising interaction. Quantum algorithms can be performed with the help of appropriate radio-frequency pulses. In addition to the standard nearest-neighbor Ising coupling, we also allow for a second neighbor coupling. It is shown, how to apply the 2\pi k method in this more general setting, where the additional coupling eventually allows to save a few pulses. We illustrate our results with two numerical simulations: the Shor prime factorization of the number 4 and the teleportation of a qubit along a chain of 3 qubits. In both cases, the optimal Rabi frequency (to suppress non-resonant effects) depends primarily on the strength of the second neighbor interaction.
[ { "version": "v1", "created": "Fri, 25 May 2007 04:10:10 GMT" } ]
2009-11-13T00:00:00
[ [ "López", "G. V.", "" ], [ "Gorin", "T.", "" ], [ "Lara", "L.", "" ] ]
0705.3689
Ioan Bucataru
Ioan Bucataru, Radu Miron
The geometry of systems of third order differential equations induced by second order Lagrangians
null
Mediterranean Journal of Mathematics, vol 6, no.4 (2009), 487-504
10.1007/s00009-009-0020-9
null
math.DG math.DS
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A dynamical system on the total space of the fibre bundle of second order accelerations, $T^2M$, is defined as a third order vector field $S$ on $T^2M$, called semispray, which is mapped by the second order tangent structure into one of the Liouville vector field. For a regular Lagrangian of second order we prove that this semispray is uniquely determined by two associated Cartan-Poincar\'e one-forms. To study the geometry of this semispray we construct a nonlinear connection, which is a Lagrangian subbundle for the presymplectic structure. Using this semispray and the associated nonlinear connection we define covariant derivatives of first and second order. With respect to this, the second order dynamical derivative of the Lagrangian metric tensor vanishes.
[ { "version": "v1", "created": "Fri, 25 May 2007 04:46:00 GMT" }, { "version": "v2", "created": "Thu, 11 Sep 2008 09:59:36 GMT" } ]
2009-11-17T00:00:00
[ [ "Bucataru", "Ioan", "" ], [ "Miron", "Radu", "" ] ]
0705.3690
Hugues Berry
Benoit Siri (INRIA Futurs), Hugues Berry (INRIA Futurs), Bruno Cessac (INLN), Bruno Delord (ANIM), Mathias Quoy (ETIS)
A mathematical analysis of the effects of Hebbian learning rules on the dynamics and structure of discrete-time random recurrent neural networks
null
null
null
null
nlin.CD q-bio.NC
null
We present a mathematical analysis of the effects of Hebbian learning in random recurrent neural networks, with a generic Hebbian learning rule including passive forgetting and different time scales for neuronal activity and learning dynamics. Previous numerical works have reported that Hebbian learning drives the system from chaos to a steady state through a sequence of bifurcations. Here, we interpret these results mathematically and show that these effects, involving a complex coupling between neuronal dynamics and synaptic graph structure, can be analyzed using Jacobian matrices, which introduce both a structural and a dynamical point of view on the neural network evolution. Furthermore, we show that the sensitivity to a learned pattern is maximal when the largest Lyapunov exponent is close to 0. We discuss how neural networks may take advantage of this regime of high functional interest.
[ { "version": "v1", "created": "Fri, 25 May 2007 04:56:59 GMT" }, { "version": "v2", "created": "Mon, 7 Apr 2008 09:40:27 GMT" } ]
2008-04-07T00:00:00
[ [ "Siri", "Benoit", "", "INRIA Futurs" ], [ "Berry", "Hugues", "", "INRIA Futurs" ], [ "Cessac", "Bruno", "", "INLN" ], [ "Delord", "Bruno", "", "ANIM" ], [ "Quoy", "Mathias", "", "ETIS" ] ]
0705.3691
David Hsu
David Hsu (1), Aonan Tang (2), Murielle Hsu (1), and John M. Beggs (2) ((1) Department of Neurology, University of Wisconsin, Madison WI, (2) Department of Physics, Indiana University, Bloomington IN)
A simple spontaneously active Hebbian learning model: homeostasis of activity and connectivity, and consequences for learning and epileptogenesis
37 pages, 1 table, 7 figures
Phys Rev E vol 76, October 2007
10.1103/PhysRevE.76.041909
null
q-bio.NC
null
A spontaneously active neural system that is capable of continual learning should also be capable of homeostasis of both firing rate and connectivity. Experimental evidence suggests that both types of homeostasis exist, and that connectivity is maintained at a state that is optimal for information transmission and storage. This state is referred to as the critical state. We present a simple stochastic computational Hebbian learning model that incorporates both firing rate and critical homeostasis, and we explore its stability and connectivity properties. We also examine the behavior of our model with a simulated seizure and with simulated acute deafferentation. We argue that a neural system that is more highly connected than the critical state (i.e., one that is "supercritical") is epileptogenic. Based on our simulations, we predict that the post-seizural and post-deafferentation states should be supercritical and epileptogenic. Furthermore, interventions that boost spontaneous activity should be protective against epileptogenesis.
[ { "version": "v1", "created": "Fri, 25 May 2007 02:55:15 GMT" } ]
2007-10-15T00:00:00
[ [ "Hsu", "David", "" ], [ "Tang", "Aonan", "" ], [ "Hsu", "Murielle", "" ], [ "Beggs", "John M.", "" ] ]
0705.3692
Isbelia Martin
I. Martin, L. Navarro, A.J. Perez, A. Restuccia
The discrete spectrum of the D=11 bosonic M5-brane
13 pages, no figures. References have been added, typos corrected, formulae have been simplified and proof of main claim has been improved
Nucl.Phys.B794:538-551,2008
10.1016/j.nuclphysb.2007.11.012
null
hep-th
null
We prove that the spectrum of the regularized M5-brane in D=11 target space is discrete with eigenvalues extending to infinity. The proof includes the same result for the spectra of regularized bosonic p-branes in general.
[ { "version": "v1", "created": "Fri, 25 May 2007 05:21:03 GMT" }, { "version": "v2", "created": "Wed, 22 Aug 2007 06:26:37 GMT" } ]
2008-11-26T00:00:00
[ [ "Martin", "I.", "" ], [ "Navarro", "L.", "" ], [ "Perez", "A. J.", "" ], [ "Restuccia", "A.", "" ] ]
0705.3693
Jan Mandel
Jonathan D. Beezley, Jan Mandel
Morphing Ensemble Kalman Filters
17 pages, 7 figures. Added DDDAS references to the introduction
null
10.1111/j.1600-0870.2007.00275.x
UCDHSC CCM Report 240
math.DS cs.CV math.ST physics.ao-ph stat.ME stat.TH
null
A new type of ensemble filter is proposed, which combines an ensemble Kalman filter (EnKF) with the ideas of morphing and registration from image processing. This results in filters suitable for nonlinear problems whose solutions exhibit moving coherent features, such as thin interfaces in wildfire modeling. The ensemble members are represented as the composition of one common state with a spatial transformation, called registration mapping, plus a residual. A fully automatic registration method is used that requires only gridded data, so the features in the model state do not need to be identified by the user. The morphing EnKF operates on a transformed state consisting of the registration mapping and the residual. Essentially, the morphing EnKF uses intermediate states obtained by morphing instead of linear combinations of the states.
[ { "version": "v1", "created": "Fri, 25 May 2007 05:46:33 GMT" }, { "version": "v2", "created": "Sun, 27 May 2007 19:38:42 GMT" }, { "version": "v3", "created": "Wed, 8 Aug 2007 17:17:36 GMT" }, { "version": "v4", "created": "Thu, 23 Aug 2007 07:45:33 GMT" } ]
2011-11-09T00:00:00
[ [ "Beezley", "Jonathan D.", "" ], [ "Mandel", "Jan", "" ] ]
0705.3694
Sergey Lebedev G.
S. G. Lebedev and A. S. Lebedev
Calculation of The Lifetimes of Thin Stripper Targets Under Bombardment of Intense Pulsed Ions
12 pages, 5 figures
Phys.Rev.STAccel.Beams11:020401,2008
10.1103/PhysRevSTAB.11.020401
null
physics.acc-ph
null
The problems of stripper target behavior in the nonstationary intense particle beams are considered. The historical sketch of studying of radiation damage failure of carbon targets under ion bombardment is presented. The simple model of evaporation of a target by an intensive pulsing beam is supposed. Stripper foils lifetimes in the nonstationary intense particle can be described by two failure mechanisms: radiation damage accumulation and evaporation of target. At the maximal temperatures less than 2500K the radiation damage are dominated; at temperatures above 2500K the mechanism of evaporation of a foil prevails. The proposed approach has been applied to the discription of behaviour of stripper foils in the BNL linac and SNS conditions.
[ { "version": "v1", "created": "Fri, 25 May 2007 06:12:23 GMT" } ]
2008-11-26T00:00:00
[ [ "Lebedev", "S. G.", "" ], [ "Lebedev", "A. S.", "" ] ]
0705.3695
Kenji Ishii
K. Ishii, K. Tsutsui, T. Tohyama, T. Inami, J. Mizuki, Y. Murakami, Y. Endoh, S. Maekawa, K. Kudo, Y. Koike, and K. Kumagai
Momentum Dependent Charge Excitations of Two-Leg Ladder: Resonant Inelastic X-ray Scattering of (La,Sr,Ca)14Cu24O41
7 pages
Phys. Rev. B 76, 045124 (2007)
10.1103/PhysRevB.76.045124
null
cond-mat.str-el
null
Momentum dependent charge excitations of a two-leg ladder are investigated by resonant inelastic x-ray scattering of (La,Sr,Ca)14Cu24O41. In contrast to the case of a square lattice, momentum dependence of the Mott gap excitation of the ladder exhibits little change upon hole-doping, indicating the formation of hole pairs. Theoretical calculation based on a Hubbard model qualitatively explains this feature. In addition, experimental data shows intraband excitation as continuum intensity below the Mott gap and it appears at all the momentum transfers simultaneously. The intensity of the intraband excitation is proportional to the hole concentration of the ladder, which is consistent with optical conductivity measurements.
[ { "version": "v1", "created": "Fri, 25 May 2007 06:13:43 GMT" } ]
2007-08-02T00:00:00
[ [ "Ishii", "K.", "" ], [ "Tsutsui", "K.", "" ], [ "Tohyama", "T.", "" ], [ "Inami", "T.", "" ], [ "Mizuki", "J.", "" ], [ "Murakami", "Y.", "" ], [ "Endoh", "Y.", "" ], [ "Maekawa", "S.", "" ], [ "Kudo", "K.", "" ], [ "Koike", "Y.", "" ], [ "Kumagai", "K.", "" ] ]
0705.3696
Shuichi Murakami
Shuichi Murakami, Satoshi Iso, Yshai Avishai, Masaru Onoda and Naoto Nagaosa
Tuning phase transition between quantum spin Hall and ordinary insulating phases
6 pages, 2 figures, to appear in Phys. Rev. B
Phys.Rev.B76:205304,2007
10.1103/PhysRevB.76.205304
null
cond-mat.mes-hall hep-th
null
An effective theory is constructed for analyzing a generic phase transition between the quantum spin Hall and the insulator phases. Occurrence of degeneracies due to closing of the gap at the transition are carefully elucidated. For systems without inversion symmetry the gap-closing occurs at \pm k_0(\neq G/2) while for systems with inversion symmetry, the gap can close only at wave-numbers k=G/2, where G is a reciprocal lattice vector. In both cases, following a unitary transformation which mixes spins, the system is represented by two decoupled effective theories of massive two-component fermions having masses of opposite signs. Existence of gapless helical modes at a domain wall between the two phases directly follows from this formalism. This theory provides an elementary and comprehensive phenomenology of the quantum spin Hall system.
[ { "version": "v1", "created": "Fri, 25 May 2007 06:15:39 GMT" }, { "version": "v2", "created": "Thu, 11 Oct 2007 05:48:23 GMT" } ]
2008-11-26T00:00:00
[ [ "Murakami", "Shuichi", "" ], [ "Iso", "Satoshi", "" ], [ "Avishai", "Yshai", "" ], [ "Onoda", "Masaru", "" ], [ "Nagaosa", "Naoto", "" ] ]
0705.3697
Marek Rogatko
Marek Rogatko
First Law of Black Saturn Thermodynamics
9 pages, RevTex, to be published in Phys.Rev.D15
Phys.Rev.D75:124015,2007
10.1103/PhysRevD.75.124015
null
hep-th gr-qc
null
The physical version and equilibrium state version of the first law of thermodynamics for a black object consisting of n-dimensional charged stationary axisymmetric black hole surrounded by $a$ black rings, the so-called black Saturn was derived. The general setting for our derivation is n-dimensional dilaton gravity with p + 1 strength form fields.
[ { "version": "v1", "created": "Fri, 25 May 2007 06:21:22 GMT" } ]
2008-11-26T00:00:00
[ [ "Rogatko", "Marek", "" ] ]