July 2004 arXiv papers — page 7

Michael van Opstall

We use the moduli space of stable curves to determine the stable (in the sense of Kollár-Shepherd-Barron) degenerations of surfaces isogenous to a product of stable curves. A recent family of examples of Catanese show that the moduli space of such smooth surfaces may have two components. The main result of this note is that these components do not meet in th

Davide L. Ferrario

Periodic and quasi-periodic solutions of the n-body problem can be found as minimizers of the Lagrangian action functional restricted to suitable spaces of symmetric paths. The main purpose of this paper is to develop a systematic approach to the equivariant minimization for the three-body problem in the three-dimensional space. First we give a finite comple

Ivana Alexandrova

We define and prove some properties of the semi-classical wavefront set. We also define and study semi-classical Fourier integral operators, of which we give a complete characterization. Lastly, we prove a generalization of the semi-classical Egorov's Theorem to manifolds of unequal dimensions.

Juan Casado-Diaz, Manuel Luna-Laynez, Francois Murat

We study the asymptotic behavior of the solution of an anisotropic, heterogeneous, linearized elasticity problem in a cylinder whose diameter $ε$ tends to zero. The cylinder is assumed to be fixed (homogeneous Dirichlet boundary condition) on the whole of one of its extremities, but only on a small part (of size $εr^ε$) of the second one; the Neumann boundar

V. V. Peller, S. R. Treil

This is a continuation of our earlier paper \cite{PT3}. We consider here operator-valued functions (or infinite matrix functions) on the unit circle $\T$ and study the problem of approximation by bounded analytic operator functions. We discuss thematic and canonical factorizations of operator functions and study badly approximable and very badly approximable

K. M. Schmidt

It was recently shown that the point spectrum of the separated Coulomb-Dirac operator H_0(k) is the limit of the point spectrum of the Dirac operator with anomalous magnetic moment H_a(k) as the anomaly parameter tends to 0; this spectral stability holds for all Coulomb coupling constants c for which H_0(k) has a distinguished self-adjoint extension if the a

Stephane Coulomb, Michel Bauer

We study minimal vertex covers and maximal matchings on trees. We pay special attention to the corresponding backbones i.e. these vertices that are occupied and those that are empty in every minimal vertex cover (resp. these egdes that are occupied and those that are empty in every maximal matching). The key result in our approach is that for trees, the back

Nguyen Tien Zung

This is a survey on natural local torus actions which arise in integrable dynamical systems, and their relations with other subjects, including: reduced integrability, local normal forms, affine structures, monodromy, global invariants, integrable surgery, convexity properties of momentum maps, localization formulas, integrable PDEs.

Thierry De La Rue

We give an example of a dynamical system which is mixing relative to one of its factors, but for which relative mixing of order three does not hold.

Tien-Cuong Dinh, Romain Dujardin, Nessim Sibony

We construct the Green current for a random iteration of "horizontal-like" mappings in two complex dimensions. This is applied to the study of a polynomial map $f:\mathbb{C}^2\to\mathbb{C}^2$ with the following properties: 1. infinity is $f$-attracting, 2. $f$ contracts the line at infinity to a point not in the indeterminacy set. Then the Green curr

Wolfgang zu Castell, Noemi Lain Fernandez, Yuan Xu

The problem of interpolation at $(n+1)^2$ points on the unit sphere $\mathbb{S}^2$ by spherical polynomials of degree at most $n$ is proved to have a unique solution for several sets of points. The points are located on a number of circles on the sphere with even number of points on each circle. The proof is based on a method of factorization of polynomials.

Yuan Xu

The second order partial difference equation of two variables $ \CD u:= A_{1,1}(x) Δ_1 \nabla_1 u + A_{1,2}(x) Δ_1 \nabla_2 u + A_{2,1}(x) Δ_2 \nabla_1 u + A_{2,2}(x) Δ_2 \nabla_2 u & \qquad \qquad \qquad \qquad + B_1(x) Δ_1 u + B_2(x) Δ_2 u = λu, $ is studied to determine when it has orthogonal polynomials as solutions. We derive conditions on $\CD$ so that

Ronald Brown

This talk gave a sketch of the contents and background to a book with the title `Nonabelian algebraic topology' being written under support of a Leverhulme Emeritus Fellowship (2002-2004) by the speaker and Rafael Sivera (Valencia). The aim is to give in one place a full account of work by R. Brown and P.J. Higgins since the 1970s which defines and appli

Jean-Marc Schlenker

A ``hyperideal circle pattern'' in $S^2$ is a finite family of oriented circles, similar to the ``usual'' circle patterns but such that the closed disks bounded by the circles do not cover the whole sphere. Hyperideal circle patterns are directly related to hyperideal hyperbolic polyhedra, and also to circle packings. To each hyperideal circl

Jens Wirth

The aim of this paper is to understand the influence of a dissipative term which is small in the sense that it is asymptotically below scaling on the asymptotic properties of solutions. A diagonalization procedure is applied in order to construct the main terms of the solution representation and this information is used to prove $L^p$--$L^q$ decay estimates.

Alexander H. W. Schmitt

We substantially refine the theory of singular principal bundles introduced in a former paper. In particular, we show that we need only honest singular principal bundles in our compactification. These are objects which carry the structure of a rational principal bundle in the sense of Ramanathan. Moreover, we arrive at a much simpler semistability condition.

Hiroyuki Chihara

We present local existence theorem of the initial value problem for third order semilinear dispersive partial differential equations in two space dimensions. This type of equations arises in the study of gravity wave of deep water, and cannot be solved by the classical energy method. To solve the initial value problem, we make full use of pseudodifferential

D. Arcara

We generalize Bertram's work on rank two vector bundles to an irreducible projective nodal curve C. We use extensions of a line bundle L by O_C and the associated `forgetful' map to study a compactification of the moduli space of semi-stable vector bundles of rank 2 and determinant L on C.

Pavle V. M. Blagojevic

\noindent The simultaneous partition problems are classical problems of the combinatorial geometry which have the natural flavor of the equivariant topology. The $k$-fan partition problems have attracted a lot of attention \cite{Aki2000}, \cite{BaMa2001}, \cite{BaMa2002} and forced some hard concrete combinatorial calculations in the equivariant cohomology \

Matthias Lesch

We discuss several natural metrics on spaces of unbounded self--adjoint operators and their relations, among them the Riesz and the graph metric. We show that the topologies of the spaces of Fredholm operators resp. invertible operators depend heavily on the metric. Nevertheless we prove that in all cases the spectral flow is up to a normalization the only i

Tristan McLoughlin, Ian Swanson

The complicated non-linear sigma model that characterizes the first finite-radius curvature correction to the pp-wave limit of IIB superstring theory on AdS_5 x S^5 has been shown to generate energy spectra that perfectly match, to two loops in the modified 't Hooft parameter lambda', finite R-charge corrections to anomalous dimension spectra of larg

A. Gruppuso, E. Roessl, M. Shaposhnikov

We present a brane-world scenario in which two regions of $AdS_5$ space-time are glued together along a 3-brane with constant positive curvature such that {\em all} spatial dimensions form a compact manifold of topology $S^4$. It turns out that the induced geometry on the brane is given by Einstein's static universe. It is possible to achieve an anisotro

Alessandra Agostini, Giovanni Amelino-Camelia, Michele Arzano, Francesco D'Andrea

We examine some alternative possibilities for an action functional for $κ$-Minkowski noncommutative spacetime, with an approach which should be applicable to other spacetimes with coordinate-dependent commutators of the spacetime coordinates ($[x_μ,x_ν]=f_{μ,ν}(x)$). Early works on $κ$-Minkowski focused on $κ$-Poincaré covariance and the dependence of the ac

J. M. Isidro

Superimposed D-branes have matrix-valued functions as their transverse coordinates, since the latter take values in the Lie algebra of the gauge group inside the stack of coincident branes. This leads to considering a classical dynamics where the multiplication law for coordinates and/or momenta, being given by matrix multiplication, is nonabelian. Quantisat

N. Kitanine, J. M. Maillet, N. A. Slavnov, V. Terras

We obtain a new multiple integral representation for the spin-spin correlation functions of the XXZ spin-1/2 infinite chain. We show that this representation is closely related with the partition function of the six-vertex model with domain wall boundary conditions.

Gerald V. Dunne, Jin Hur, Choonkyu Lee, Hyunsoo Min

The fermion determinant in an instanton background for a quark field of arbitrary mass is studied using the Schwinger proper-time representation with WKB scattering phase shifts for the relevant partial-wave differential operators. Previously, results have been obtained only for the extreme small and large quark mass limits, not for intermediate interpolatin

R. S. Thorne, A. D. Martin, R. G. Roberts, W. J. Stirling

I present a brief summary of the most important updates in the MRST determinations of the NLO and NNLO parton distributions. I concentrate on uncertainties due to input assumptions and possible theoretical corrections, particularly isospin violation, QED corrections, NNLO and corrections at low Q^2 and small x.

A. M. Cooper-Sarkar

The ZEUS inclusive cross-section data from HERA-I, for charged and neutral current processes, taken with $e^+$ and $e^-$ beams, have been used in a new NLO QCD analysis to extract the parton distribution functions (PDFs) of the proton within a single experiment. The precision of the high-$x$ gluon determination is improved by using ZEUS differential cross-se

Harald Fritzsch, Alp Deniz Özer

We show that the observed quark masses seem to be consistent with a simple scaling law. Due to the precise values of the heavy quarks we are able to calculate the quark masses in the light quark sector. We discuss a possible value for the strange quark mass. We show that the u-type quark masses obey the scaling law very well.

Thomas D. Cohen

It is noted that if large Nc continuum reduction applies to an observable, then that observable is independent of temperature for all temperatures below some critical value. This fact, plus the fact that mesons and glueballs are weakly interacting at large Nc is used as the basis for a derivation of large Nc continuum reduction for the chiral condensate. The

J. P. B. C. de Melo, T. Frederico

The electromagnetic current of spin-1 composite particles does not transform properly under rotations if only the valence contribution is considered in the light-front model. In particular, the plus component of the current, evaluated only for the valence component of the wave function, in the Drell-Yan frame violates rotational symmetry, which does not allo

S. Ferrag

The LHC data will provide sensitivity to an unification of the couplings at low energies in the range $\sim$10-100 TeV. It is demonstrated in this note that the lack of knowledge on the proton structure, specifically its gluon distribution, can lower dramatically the sensitivity of bare cross section measurements to this physics. However, some more elaborate

Milind V. Diwan

In this paper I will discuss how an intense beam of high energy neutrinos produced with conventional technology could be used to further our understanding of neutrino masses and mixings. I will describe the possibility of building such a beam at existing U.S. laboratories. Such a project couples naturally to a large ($>$ 100 kT) multipurpose detector in a ne

Marek Tasevsky

Flavour inclusive, udsc and b fragmentation functions in biased and unbiased jets and gluon fragmentation functions in biased jets are measured in e+e- annihilations using OPAL data collected at energies Ecms = 91.2 and 183-209 GeV.

Guido Cognola, Sergio Zerbini

Motivated by the dark energy issue, the minisuperspace approach for general relativistic cosmological theories is outlined.

Gregory J. Galloway

We discuss some global properties of cosmological spacetimes of de Sitter type, based on results with Lars Andersson obtained in hep-th/0202161. We relate the geometry and topology of conformal infinity to the occurrence of singularities in such spacetimes, thereby extending to a much broader context certain properties of some well-known cosmological models.

Alexandr V. Timoshkin

We consider the asymptoic behaviour of the Chern - Simons (CS) theory with matter in curved space - time. The asymptotics of effective couplings are discussed.

K. Konwar, I. Mandoiu, A. Russell, A. Shvartsman

A critical problem in the emerging high-throughput genotyping protocols is to minimize the number of polymerase chain reaction (PCR) primers required to amplify the single nucleotide polymorphism loci of interest. In this paper we study PCR primer set selection with amplification length and uniqueness constraints from both theoretical and practical perspecti

S. N. Gvasaliya, B. Roessli, R. A. Cowley, S. G. Lushnikov

The low-energy part of the vibration spectrum in KNbO$_3$ was studied by cold neutron inelastic scattering in the cubic phase. In addition to acoustic phonons, we observe strong diffuse scattering, which consists of two components. The first one is quasi-static and has a temperature-independent intensity. The second component appears as quasi-elastic scatter

I. S. Tupitsyn, P. C. E. Stamp

Comment on the paper: "Magnetization Process of Single Molecule Magnets at Low Temperatures" of J.F.Fernandez and J.J.Alonso (PRL 91, 047202 (2003)).

R. Wang, T. Pavlin, M. S. Rosen, R. W. Mair

In this work we present measurements of permeability, effective porosity and tortuosity on a variety of rock samples using NMR/MRI of thermal and laser-polarized gas. Permeability and effective porosity are measured simultaneously using MRI to monitor the inflow of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the ti

Yilong Han, David G. grier

We demonstrate that the configurational temperature formalism can be derived from the classical hypervirial theorem, and introduce a hierarchy of hyperconfigurational temperature definitions, which are particularly well suited for experimental studies. We then use these analytical tools to probe the electrostatic interactions in monolayers of charge-stabiliz

R. Wang, M. S. Rosen, D. Candela, R. W. Mair

We report initial NMR studies of gas dynamics in a particle bed fluidized by laser-polarized xenon (129Xe) gas. We have made preliminary measurements of two important characteristics: gas exchange between the bubble and emulsion phases; and the gas velocity distribution in the bed. We used T2* contrast to differentiate the bubble and emulsion phases by choos

S. Koval, J. Kohanoff, J. A. Lasave, G. Colizzi

By means of extensive first-principles calculations we studied the ferroelectric phase transition and the associated isotope effect in KH2PO4 (KDP)

Chungwei Lin, Andrew. J. Millis

A model for semimetals such as $EuB_6$, in which band overlaps are controlled by magnetic order, is presented and is solved in the dynamical mean field approximation. First order phase boundaries are computed by evaluating free energies of different states. The phase diagram is determined. A specific and physically reasonable choice of parameters is found to

A. O. Govorov, A. V. Kalameitsev

We consider the optical properties of a single magnetic impurity in a self-assembled quantum dot. We show that using the resonant pumping one can address and manipulate selectively individual spin states of a magnetic impurity. The mechanisms of resonant optical polarization of a single impurity in a quantum dot involve anisotropic exchange interactions and

G. Y. Chitov, C. Gros

We propose a mechanism for the observed stacking charge order in the quarter-filled ladder compound NaV2O5. Via a standard mapping of the charge degrees of freedom onto Ising spins we explain the stacking order as a result of competition between couplings of the nearest and next-nearest planes with the 4-fold degenerate super-antiferroelectric in-plane order

Xindong Wang, X. -G. Zhang

A general spin symmetry argument is proposed for spin currents in semiconductors. In particular, due to the symmetry with respect to spin polarization of the helicity eigenstates of the Luttinger Hamiltonian for a hole-doped semiconductor, the spin polarized flux from a single helicity eigenstate induced by an external electric field, is canceled exactly whe

M. Casartelli, L. Dall'Asta, E. Rastelli, S. Regina

The lattice spin model, with nearest neighbor ferromagnetic exchange and long range dipolar interaction, is studied by the method of time series for observables based on cluster configurations and associated partitions, such as Shannon entropy, Hamming and Rohlin distances. Previous results based on the two peaks shape of the specific heat, suggested the exi

C. P. Sun, J. -Y. Lin, S. Mollah, P. L. Ho

Magnetic field dependence of low temperature specific heat of spinel oxide superconductor LiTi_2O_4 has been elaborately investigated. In the normal state, the obtained electronic coefficient of specific heat gamma_n = 19.15 mJ/mol K2, the Debye temperature is 657 K and some other parameters are compared with those reported earlier. The superconducting trans

Denis Danilov, Britta Nestler

We present adaptive finite element simulations of dendritic and eutectic solidification in binary and ternary alloys. The computations are based on a recently formulated phase-field model that is especially appropriate for modelling non-isothermal solidification in multicomponent multiphase systems. In this approach, a set of governing equations for the phas

Raksha Sharma, Subhalakshmi Lamba, S. Annapoorni, Parmanand Sharma

Gamma - Iron Oxide prepared by sol -gel process was used to produce nanocomposites with polyaniline of varying aniline concentrations. TEM shows the presence of chain like structure for lower polyaniline concentration. The room temperature hysteresis curves show finite coercivity of 160 Oe for all the composites while the saturation magnetization was found t

M. Pretti, C. Buzano

We investigate a lattice-fluid model of water, defined on a three-dimensional body centered cubic lattice. Model molecules possess a tetrahedral symmetry, with four equivalent bonding arms, aiming to mimic the formation of hydrogen bonds. The model is similar to the one proposed by Roberts and Debenedetti [J. Chem. Phys. 105, 658 (1996)], simplified in that

H. Yabu, Y. Takayama, T. Suzuki

The phase structures of the boson-fermion (B and F) mixed condensates of atomic gas are discussed under the existence of boson-fermion composite fermions (quasi-bound states) BF from the equilibrium in B+F -> BF. Especially we discuss the competitions between the BF degenerate states and the Bose-Einstein condensates (BEC) in low-T. The criterion for the BEC

H. Yabu, Y. Takayama, T. Suzuki, P. Schuck

The boson-fermion atomic bound states (composite fermion) and their roles for the phase structures are studied in a bose-fermi mixed condensate of atomic gas in finite temperature and density. The two-body scattering equation is formulated for a boson-fermion pair in the mixed condensate with the Yamaguchi-type potential. By solving the equation, we evaluate

Ying-Ju Wang, Dana Z. Anderson, Victor M. Bright, Eric A. Cornell

An atom Michelson interferometer is implemented on an "atom chip." The chip uses lithographically patterned conductors and external magnetic fields to produce and guide a Bose-Einstein condensate. Splitting, reflecting, and recombining of condensate atoms are achieved by a standing-wave light field having a wave vector aligned along the atom waveguid

N. Kumar

Starting with an expression, due originally to Einstein, for the shear viscosity \textit{$η$}(\textit{$δϕ$}) of a liquid having a small fraction \textit{$δϕ$}by volume of solid particulate matter suspended in it at random, we derive an effective-medium viscosity \textit{$η$}(\textit{$ϕ$}) for arbitrary \textit{$ϕ$} which is precisely of the Vogel-Fulcher for

Zhongqing Wu, Ningdong Huang, Zhirong Liu, Jian Wu

Using a first-principles-based approach, we determine the ferroelectric pattern in PbZr$_{0.5}$Ti$_{0.5}$O$_3$ ultrathin film. It is found that vortex stripes are formed in the system and they are responsible for the 180$^\circ$ domains observed. When a local external field is exerted, the vortex stripe transforms into the vortex loop structure, which leads

Takeshi Mizushima, Naoko Kobayashi, Kazushige Machida

We theoretically investigate vortex-lattice phases of rotating spinor Bose-Einstein condensates (BEC) with the ferromagnetic spin-interaction by numerically solving the Gross-Pitaevskii equation. The spinor BEC under slow rotation can sustain a rich variety of exotic vortices due to the multi-component order parameters, such as the Mermin-Ho and Anderson-Tou

J. Ashkenazi

The carriers in the high-Tc cuprates are found to be polaron-like "stripons" carrying charge and located in stripe-like inhomogeneities, "quasi-electrons" carrying charge and spin, and "svivons" carrying spin and some lattice distortion. The anomalous spectroscopic and transport properties of the cuprates are understood. The stripe-li

J. -N. Aqua, F. Cornu

The aim of the paper is to study the renormalizations of the charge and of the screening length that appear in the large-distance behavior of the effective pairwise interaction between two charges in a dilute electrolyte solution, both along a dielectric wall and in the bulk. The electrolyte is described by the primitive model in the framework of classical s

K. Kudo, M. Yamazaki, T. Kawamata, T. Adachi

We have measured the thermal conductivity in the $ab$-plane of La$_{2-x}$Sr$_x$CuO$_4$ ($x =$ 0.10, 0.115, 0.13) in magnetic fields up to 14 T parallel to the c-axis and also parallel to the $ab$-plane. By the application of magnetic fields parallel to the c-axis, the thermal conductivity has been found to be suppressed at low temperatures below the temperat

Elena Pierpaoli, Rosalba Perna

We investigate the possible contribution from the emission of accretion flows around supermassive black holes in early type galaxies to current measurements of the Cosmic Microwave Background (CMB) at radio frequencies. We consider a range of luminosities suggested by targeted radio observations and accretion models and compute the residual contribution of t

Jacob D. Bekenstein

I present an elementary primer of black hole physics, including its general relativity basis, all peppered with astrophysical illustrations. Following a brief review of the process stellar collapse to a black hole, I discuss the gravitational redshift, particle trajectories in gravitational fields, the Schwarzschild and Kerr solutions to Einstein's equat

Maria Messineo

Asymptotic Giant Branch (AGB) stars are good tracers of the Galactic structure. They are bright in the infrared and can therefore be detected even in the most obscured regions of the Galaxy. Maser emission from their circumstellar envelopes can be detected throughout the Galaxy, and reveals the stellar line-of-sight velocities with an accuracy of a few km/s.

Jordi Jose

Classical novae are fascinating stellar events, at the crossroads of astrophysics, nuclear physics and cosmochemistry. In this review, we outline the history of nova modeling with special emphasis on recent advances and perspectives in multidimensional simulations. Among the topics that are covered, we analyze the interplay between nova outbursts and the Gal

A. Spagna, D. Carollo, M. G. Lattanzi, B. Bucciarelli

We present an alternative method for the kinematic analysis of high proper motion surveys and discuss its application to the survey of Oppenheimer et al. (2001) for the selection of reliable halo white dwarfs (WDs). The local WD space density we estimate is (1-2) 10^{-5}MSun/pc^{3}, which is about an order of magnitude smaller than the value derived in Oppen

C. R. O'Dell, P. R. McCullough, M. Meixner

Through HST imaging of the inner part of the main-ring of the Helix Nebula together with CTIO 4-m images of the fainter outer parts, we have an unprecedented-quality view of the nearest bright planetary nebula. These images have allowed determination that the main-ring of the nebula is composed of an inner-disk of about 499\arcsec diameter (0.52 pc) surround

G. C. McLaughlin, R. Surman

We discuss the possibility that r-process nucleosynthesis may occur in the winds from gamma ray burst accretion disks. This can happen if the temperature of the disk is sufficiently high that electron antineutrinos are trapped as well as neutrinos. This implies accretion disks with greater than a solar mass per second accretion rate, although lower accretion

Joerg R Hoerandel

The present experimental status concerning the composition of cosmic rays in the PeV region is reviewed. The results are compared to predictions of contemporary models for the acceleration and propagation of galactic cosmic rays.

A. Pasquali, G. De Marchi, L. Pulone, M. S. Brigas

Data obtained with the NICMOS instrument on board the Hubble Space Telescope (HST) have been used to determine the H-band luminosity function (LF) and mass function (MF) of three stellar fields in the globular cluster M15, located ~7' from the cluster centre. The data confirm that the cluster MF has a characteristic mass of ~0.3 Msolar, as obtained by Pa

E. O'Sullivan, T. J. Ponman

We present analysis of a Chandra observation of the elliptical galaxy NGC 4555. The galaxy lies in a very low density environment, either isolated from all galaxies of similar mass or on the outskirts of a group. Despite this, NGC 4555 has a large gaseous halo, extending to ~60 kpc. We find the mean gas temperature to be ~0.95 keV and the Iron abundance to b

Maria Lugaro, Claudio Ugalde, Amanda I. Karakas, Joachim Gorres

We present nucleosynthesis calculations and the resulting 19F stellar yields for a large set of models with different masses and metallicity. We find that the production of fluorine depends on the temperature of the convective pulses, the amount of primary 12C mixed into the envelope by third dredge up and the extent of the partial mixing zone. Then we perfo

U. Becciani, R. Capuzzo Dolcetta, A. Costa, P. Di Matteo

Astrocomp is a joint project, developed by the INAF-Astrophysical Observatory of Catania, University of Roma La Sapienza and Enea. The project has the goal of providing the scientific community of a web-based user-friendly interface which allows running parallel codes on a set of high-performance computing (HPC) resources, without any need for specific knowl

Kenneth R. Sembach, Todd M. Tripp, Blair D. Savage, Philipp Richter

We present HST and FUSE observations of the intergalactic absorption toward PG1116+215 in the 900-3000 A spectral region. We detect 25 Ly-alpha absorbers at rest-frame equivalent widths W_r > 30 mA, yielding (dN/dz)_Ly-alpha = 154+/-18 over an unblocked redshift path of 0.162. Two additional weak Ly-alpha absorbers with W_r ~ 15-20 mA are also present. Eight

M. Perucho, M. Hanasz, J. M. Marti, H. Sol

The effects of relativistic dynamics and thermodynamics in the development of Kelvin-Helmholtz instabilities in planar, relativistic jets along the early phases (namely linear and saturation phases) of evolution has been studied by a combination of linear stability analysis and high-resolution numerical simulations for the most unstable first reflection mode

Nurgali Takibayev

At the early stage of the Universe evolution, when photons and neutrinos are no longer able to prevent nucleosynthesis, the key role is given to neutron component of matter. Neutron component creates a certain variety of the lightest chemical elements and disappears leaving a sufficient portion of Helium isotopes and some tiny portions of Li and Be isotopes.

Ismael Cognard, Donald C. Backer

We report on the observation of a very small glitch observed for the first time in a millisecond pulsar, PSR B1821-24 located in the globular cluster M28. Timing observations were mainly conducted with the Nancay radiotelescope (France) and confirmation comes from the 140ft radiotelescope at Green Bank and the new Green Bank Telescope data. This event is cha

S. Moehler

Globular clusters offer ideal laboratories to test the predictions of stellar evolution. When doing so with spectroscopic analyses during the 1990s, however, the parameters we derived for hot horizontal branch stars deviated systematically from theoretical predictions. The parameters of cooler, A-type horizontal branch stars, on the other hand, were consiste

Arturo Lucas-Serrano, Jose A. Font, Jose M. Ibanez, Jose M. Marti

We assess the suitability of a recent high-resolution central scheme developed by Kurganov & Tadmor (2000) for the solution of the relativistic hydrodynamics equations. The novelty of this approach relies on the absence of Riemann solvers in the solution procedure. The computations we present are performed in one and two spatial dimensions in Minkowski space

Daniel J. Eisenstein, Martin White

We discuss the systematic uncertainties in the recovery of dark energy properties from the use of baryon acoustic oscillations as a standard ruler. We demonstrate that while unknown relativistic components in the universe prior to recombination would alter the sound speed, the inferences for dark energy from low-redshift surveys are unchanged so long as the

N. L. Harshman, N. Licata

This paper describes Clebsch-Gordan coefficients (CGCs) for unitary irreducible representations (UIRs) of the extended quantum mechanical Poincaré group $\pt$. `Extended' refers to the extension of the 10 parameter Lie group that is the Poincaré group by the discrete symmetries $C$, $P$, and $T$; `quantum mechanical' refers to the fact that we consid

Jason R. Smith, Gerald A. Miller

We calculate the electromagnetic form factors of a bound proton. The Chiral Quark-Soliton model provides the quark and antiquark substructure of the proton, which is embedded in nuclear matter. This procedure yields significant modifications of the form factors in the nuclear environment. The sea quarks are almost completely unaffected, and serve to mitigate

Spyros D. Avramis, Alex Kehagias

We construct the most general couplings of a bulk seven-dimensional Yang-Mills-Einstein N=2 supergravity with a boundary six-dimensional chiral N=(0,1) theory of vectors and charged hypermultiplets. The boundary consists of two brane worlds sitting at the fixed points of an S^1/Z_2 compactification of the seven-dimensional bulk supergravity. The resulting 6D

D. H. Correa, C. D. Fosco, F. A. Schaposnik, G. Torroba

We consider planar noncommutative theories such that the coordinates verify a space-dependent commutation relation. We show that, in some special cases, new coordinates may be introduced that have a constant commutator, and as a consequence the construction of Field Theory models may be carried out by an application of the standard Moyal approach in terms of

Andreas Brandhuber, Bill Spence, Gabriele Travaglini

We propose a new, twistor string theory inspired formalism to calculate loop amplitudes in N=4 super Yang-Mills theory. In this approach, maximal helicity violating (MHV) tree amplitudes of N=4 super Yang-Mills are used as vertices, using an off-shell prescription introduced by Cachazo, Svrcek and Witten, and combined into effective diagrams that incorporate

Thomas F. Jordan

For quantum systems described by finite matrices, linear and affine maps of matrices are shown to provide equivalent descriptions of evolution of density matrices for a subsystem caused by unitary Hamiltonian evolution in a larger system; an affine map can be replaced by a linear map, and a linear map can be replaced by an affine map. There may be significan

A. A. Tseytlin

We review recent progress in checking AdS/CFT duality in the sector of ''semiclassical'' string states dual to ''long'' scalar operators of N=4 super Yang-Mills theory. In particular, we discuss the effective action approach, in which the same sigma model type action describing coherent states is shown to emerge from the AdS_5

J. A. Sellwood

It has been known for some time that rotating bars in galaxies slow due to dynamical friction against the halo. However, recent attempts to use this process to place constraints on the dark matter density in galaxies and possibly also to drive dark matter out of the center have been challenged. This paper uses simplified numerical experiments to clarify seve

Leonardo Modesto

We apply techniques recently introduced in quantum cosmology to the Schwarzschild metric inside the horizon and near the black hole singularity at r = 0. In particular, we use the quantization introduced by Husain and Winkler, which is suggested by Loop Quantum Gravity and is based on an alternative to the Schrodinger representation introduced by Halvorson.

Jean-Francois Burnol

Une danse avec co-Poisson: 1 Introduction: Sommes, Propriete de support, Co-sommes, Mellin et dzêta, Fonctions entieres et meromorphes 2 Docteur Poisson et Mister Co: Des theoremes de co-Poisson, Lemmes sur les sommes et les co-sommes, Preuve du theoreme 2.4, Un theoreme de Poisson presque sûr, Formule integrale de co-Poisson, Sommes de Riemann, Un autre the

F. Ferrer, J. A. Grifols

Scalar mediated interactions among baryons extend well above the Compton wavelength, when they are embedded in a Bose-Einstein condensate composed of the mediating particles. Indeed, this non-trivial environment results in an infinite-ranged interaction. We show that if the Dark Matter of the Universe is composed of such a condensate, the imprints of an inte

M. Berkooz, B. Durin, B. Pioline, D. Reichmann

Misner space, also known as the Lorentzian orbifold $R^{1,1}/boost$, is the simplest tree-level solution of string theory with a cosmological singularity. We compute tree-level scattering amplitudes involving twisted states, using operator and current algebra techniques. We find that, due to zero-point quantum fluctuations of the excited modes, twisted strin

Sebastian Kubis

The beta equilibrated dense matter with kaon condensate is analyzed with respect to extended stability conditions including charge fluctuations. This kind of the diffusive instability, appeared to be common property in the kaon condensation case. Results for three different nuclear models are presented.

Jacek Niemiec

The current status of the theory of particle acceleration at relativistic shocks is presented, and a few possible scenarios for ultra-high-energy cosmic ray production at such shocks are briefly discussed.

David N. Walters, Simon Hands

We present initial results of a numerical investigation of the chiral symmetry restoring transition in the (3+1)-dimensional Nambu -- Jona-Lasinio model with both non-zero baryon chemical potential (mu_B) and isospin chemical potential (mu_I). With non-zero isospin chemical potential, the model suffers from a sign problem. We proceed in two ways: (i) We perf

Ilya Kapovich, Richard Weidmann

We prove that the rank problem is decidable in the class of torsion-free word-hyperbolic Kleinian groups. We also show that every group in this class has only finitely many Nielsen equivalence classes of generating sets of a given cardinality.

Hossein Shojaie, Mehrdad Farhoudi

A new varying-$c$ cosmological model constructed using two additional assumptions, which was introduced in our previous work, is briefly reviewed and the dynamic equation of the model is derived distinctly from a semi-Newtonian approach. The results of this model, using a $Λ$ term and an extra energy-momentum tensor, are considered separately. It is shown th

Hanno Essen

Theory and experiment on the London moment is reviewed. A simple mathematical model is motivated and then used to study the responses of a spherical superconductor to an external field and to rotation. It reveals a connection between perfect diamagnetism (Meissner effect) and the London moment. In the model neither of these are exact but the deviation from B

Joseph H. Silverman

We apply Vojta's conjecture to blowups and deduce a number of deep statements regarding (generalized) greatest common divisors on varieties, in particular on projective space and on abelian varieties. Special cases of these statements generalize earlier results and conjectures. We also discuss the relationship between generalized greatest common divisors