March 1998 arXiv papers — page 14

Armin Scrinzi, Bernard Piraux

We discuss a method of solving the time dependent Schrodinger equation for atoms with two active electrons in a strong laser field, which we used in a previous paper [A. Scrinzi and B. Piraux, Phys. Rev. A 56, R13 (1997)] to calculate ionization, double excitation and harmonic generation in Helium by short laser pulses. The method employs complex scaling and

H. V. von Geramb, K. A. Amos, H. Labes, M. Sander

We analyse the SM97 partial wave amplitudes for nucleon--nucleon (NN) scattering to 2.5 GeV, in which resonance and meson production effects are evident for energies above pion production threshold. Our analyses are based upon boson exchange or quantum inversion potentials with which the sub-threshold data are fit perfectly. Above 300 MeV they are extrapolat

D. Blaschke, A. Hoell, C. D. Roberts, S. Schmidt

We calculate the chiral and thermal susceptibilities for two confining Dyson-Schwinger equation models of QCD with two light flavours, a quantitative analysis of which yields the critical exponents, beta and delta, that characterise the second-order chiral symmetry restoration transition. The method itself is of interest, minimising the influence of numerica

R. Nouicer, C. Beck, S. J. Sanders, A. Szanto de Toledo

Fragment-fragment-$γ$ triple coincidence measurements of the $^{28}$Si~$+$~$^{28}$Si reaction at E$_{\rm c.m.}$~=~55.8 MeV, carefully chosen to populate a well known quasi-molecular resonance in $^{56}$Ni, have been performed at the VIVITRON tandem facility by using the Eurogam Phase~II $γ$-ray spectrometer. In the $^{28}$Si~$+$~$^{28}$Si reaction, the reson

Robert Osserman

We prove a ``general shrinking lemma'' that resembles the Schwarz--Pick--Ahlfors Lemma and its many generalizations, but differs in applying to maps of a finite disk into a disk, rather than requiring the domain of the map to be complete. The conclusion is that distances to the origin are all shrunk, and by a limiting procedure we can recover the ori

J. D. Deuschel, O. Zeitouni

We study the fluctuations, in the large deviations regime, of the longest increasing subsequence of a random i.i.d. sample on the unit square. In particular, our results yield the precise upper and lower exponential tails for the length of the longest increasing subsequence of a random permutation.

Gregory F. Lawler

The growth exponent $α$ for loop-erased or Laplacian random walk on the integer lattice is defined by saying that the expected time to reach the sphere of radius $n$ is of order $n^α$. We prove that in two dimensions, the growth exponent is strictly greater than one. The proof uses a known estimate on the third moment of the escape probability and an improve

J. Denef, F. Loeser

We prove a character sum identity for Coxeter arrangements which is a finite field analogue of Macdonald's conjecture proved by Opdam.

Omer F. Dayi

Quantum Hall effect wavefunctions corresponding to the filling factors 1/2p+1, 2/2p+1,..., 2p/2p+1, 1, are shown to form a basis of irreducible cyclic representation of the quantum algebra U_q(sl(2)) at q^{2p+1}=1. Thus, the wavefunctions Ψ_{P/Q} possessing filling factors P/Q<1 where Q is odd and P, Q are relatively prime integers are classified in terms of

R. B. Zhang

The quantum general linear supergroup GLq(m|n) is defined and its structure is studied systematically. Quantum homogeneous supervector bundles are introduced following Connes&#39; theory, and applied to develop the representation theory of GLq(m|n). Quantum Frobenius reciprocity is proven, and a Borel - Weil theorem is established for the irreducible covaria

Arvind Rajaraman

We calculate the absorption cross section on a black threebrane of two-form perturbations polarized along the brane. The equations are coupled and we decouple them for s-wave perturbations. The Hawking rate is suppressed at low energies, and this is shown to be reflected in the gauge theory by a coupling to a higher dimension operator.

L. A. Manzoni, B. M. Pimentel, J. L. Tomazelli

We consider the (2+1)-dimensional massive Thirring model as a gauge theory, with one fermion flavor, in the framework of the causal perturbation theory and address the problem of dynamical mass generation for the gauge boson. In this context we get an unambiguous expression for the coefficient of the induced Chern-Simons term.

S. C. Gibbons, R. N. Mohapatra, S. Nandi, A. Raychaudhuri

It has been observed that simultaneous explanation of the solar and atmospheric neutrino deficits and the reported evidence for $ν_μ\to ν_{e}$ oscillation from the Los Alamos Liquid Scintillator Detector (LSND) requires at least one extra neutrino species in addition to the three known ones. The extra neutrino must be sterile with respect to the known weak i

Apostolos Pilaftsis

We consider an Abelian model with a CP-conserving Higgs potential spanned by two complex Higgs fields. The CP invariance of the Higgs potential is then broken explicitly beyond the Born approximation by introducing soft-CP-violating Yukawa interactions. Based on the non-renormalization theorem, we derive the consistency conditions under which a CP-odd counte

M. Diehl

The pomeron model of Donnachie and Landshoff does not conserve the electromagnetic current when applied to diffractive reactions such as electroproduction of a quark-antiquark pair or of a vector meson. We propose a treatment of this problem which ensures a physical behaviour of cross sections in the photoproduction limit and show that it leads to results ra

F. Donato, N. Fornengo, S. Scopel

The effects of a possible rotation of the galactic dark halo on the calculation of the direct detection rates for particle dark matter are analyzed, with special attention to the extraction of the upper limits on the WIMP--nucleon scalar cross section from the experimental data. We employ a model of dark halo rotation which describes the maximal possible eff

S. Heinemeyer

Recent results on two--loop calculations in the MSSM are reviewed. The computation of the QCD corrections to Δρ, Δr and to the mass of the lightest Higgs boso in the MSSM are presented.

B. A. Arbuzov, M. Yu. Osipov

The problem of possible deviations from the Standard Model is considered in the framework of a variant of dynamical electroweak symmetry breaking. It comes clear, that the parameters of the theory, being obtained earlier and describing deviations from SM in Z --> \bar b b decay, are also consistent with the existence of a nontrivial solution for vertex \bar

Matthew J. Strassler

Recent discoveries in supersymmetric gauge theories have significant implications for our understanding for QCD and of field theory in general. The phases of N=1 supersymmetric QCD (SQCD) are discussed, and the possibility of similar phases in non-supersymmetric QCD is emphasized. It is described how duality in SQCD links many previously known duality transf

Friedrich W. Hehl, José Socorro

We find a class of electrically charged exact solutions for a toy model of metric-affine gravity. Their metric is of the Plebański-Demiański type and their nonmetricity and torsion are represented by a triplet of covectors with dilation, shear, and spin charges.

C. Barcelo, L. J. Garay

The effects of asymptotically anti-de Sitter wormholes in low-energy field theory are calculated in full detail for three different matter contents: a conformal scalar field, an electromagnetic field and gravitons. There exists a close relation between the choice of vacuum for the matter fields and the selection of a basis of the Hilbert space of anti-de Sit

Horst R. Beyer

The completeness of the quasinormal modes of the wave equation with Poeschl-Teller potential is investigated. A main result is that after a large enough time $t_0$, the solutions of this equation corresponding to $C^{\infty}$-data with compact support can be expanded uniformly in time with respect to the quasinormal modes, thereby leading to absolutely conve

Jacob D. Bekenstein, Marcelo Schiffer

Inertial motion superradiance, the emission of radiation by an initially unexcited system moving inertially but superluminally through a medium, has long been known. Rotational superradiance, the amplification of radiation by a rotating rigid object, was recognized much later, principally in connection with black hole radiances. Here we review the principles

Jacob D. Bekenstein

In some respects the black hole plays the same role in gravitation that the atom played in the nascent quantum mechanics. This analogy suggests that black hole mass $M$ might have a discrete spectrum. I review the physical arguments for the expectation that black hole horizon area eigenvalues are uniformly spaced, or equivalently, that the spacing between st

Robert Haslinger, Robert Joynt

The existence of Josephson tunneling has been demonstrated between YBa$_2$Cu$_3$O$_{7-δ}$ and Pb with the current flowing along the c-axis of YBa$_2$Cu$_3$O$_{7-δ}$. This is presumed to come from an s-wave component of the superconductivity in YBa$_2$Cu$_3$O$_{7-δ}$, perhaps induced by the orthorhombic distortion. This hypothesis by itself appears to be in c

T. Kottos, F. M. Izrailev, A. Politi

The transfer matrix method is applied to finite quasi-1D disordered samples attached to perfect leads. The model is described by structured band matrices with random and regular entries. We investigate numerically the level spacing distribution for finite-length Lyapunov exponents as well as the conductance and its fluctuations for different channel numbers

K. Maisinger, U. Schollwoeck

We apply the transfer matrix DMRG to frustrated quantum spin chains, going down to T=0.025 while being in the thermodynamic limit. The incommensurability problem of exact diagonalization and the negative sign problem of quantum Monte Carlo vanish completely. To illustrate the method, we give results for chains with next-nearest neighbor frustration and the d

L. Chayes, A. Coniglio, J. Machta, K. Shtengel

The $q=2$ random cluster model is studied in the context of two mean field models: The Bethe lattice and the complete graph. For these systems, the critical exponents that are defined in terms of finite clusters have some anomalous values as the critical point is approached from the high density side which vindicates the results of earlier studies. In partic

Orlando S. Wagner, Guido Burkard, Vadim B. Geshkenbein, Gianni Blatter

We study vortex pinning in layered type-II superconductors in the presence of uncorrelated disorder for decoupled layers. Introducing the new concept of variable-range thermal smoothing, we describe the interplay between strong pinning and thermal fluctuations. We discuss the appearance and analyze the evolution in temperature of two distinct non-linear feat

G. Korniss, G. Brown, M. A. Novotny, P. A. Rikvold

We present recent results on two attempts at understanding and utilizing large-scale simulations of magnetic materials. In the first study we consider massively parallel implementations on a Cray T3E of the n-fold way algorithm for magnetization switching in kinetic Ising models. We find an intricate relationship between the average time increment and the si

F. Schmid, C. Stadler, H. Lange

We study coarse grained, continuum models for Langmuir monolayers by self consistent field theory and by Monte Carlo simulations. Amphiphilic molecules are represented by stiff chains of monomers with one end grafted to a planar surface. In particular, we discuss the origin of successive fluid-fluid transitions, the possible origin of tilt order and the fact

A. D. Jackson, G. M. Kavoulakis, C. J. Pethick

We consider the conditions under which solitary waves can exist in elongated clouds of Bose-Einstein condensed atoms. General expressions are derived for the velocity, characteristic size, and spatial profile of solitary waves, and the low- and high-density limits are examined.

B. Elattari, V. Kagalovsky, H. A. Weidenmueller

The presence of resonances modifies the passage of light or of electrons through a disordered medium. We generalize random matrix theory to account for this effect. Using supersymmetry, we calculate analytically the mean density of states, and the effective Lagrangean of the generating functional for the two-point function. We show that the diffusion constan

C. J. Lambert, R. Seviour, A. F. Volkov

Using a scattering matrix approach and quasiclassical Green&#39;s function technique, we calculate the conductance of the S/N system (see Fig.1). We establish that the difference between the superconducting and normal state conductance $(δG = G_s - G_n)$ is negative for large S/N interface resistances $(R_{S/N})$ and changes sign with decreasing $R_{S/N}$. T

Chuck Yeung

The surface shape of a spinning bucket of granular material is studied using a continuum model of surface flow developed by Bouchaud et al. and Mehta et al. An experimentally observed central subcritical region is reproduced by the model. The subcritical region occurs when a metastable surface becomes unstable via a nonlinear instability mechanism. The nonli

M. Mueller, F. Schmid

We review recent simulation studies of interfaces between immiscible homopolymer phases. Special emphasis is given to the presentation of efficient simulation techniques and powerful methods of data analysis, such as the analysis of capillary wave spectra. Possible reasons for polymer incompatibility and ways to relate model dependent interaction parameters

D. D. Sarma, S. R. Krishnakumar, Nirmala Chandrasekharan, E. Weschke

We report very highly resolved photoemission spectra of NiS(1-x)Se(x) across the so-called metal-insulator transition as a function of temperature as well as composition. The present results convincingly demonstrate that the low temperature, antiferromagnetic phase is metallic, with a reduced density of states at E$_F$. This decrease is possibly due to the o

Holger Stark, Joachim Stelzer, Ralf Bernhard

Recently, it was observed that water droplets suspended in a nematic liquid crystal form linear chains (Poulin et al., Science 275, 1770 (1997)). The chaining occurs, e.g., in a large nematic drop with homeotropic boundary conditions at all the surfaces. Between each pair of water droplets a point defect in the liquid crystalline order was found in accordanc

S. Sorella

A new method for the stabilization of the sign problem in the Green Function Monte Carlo technique is proposed. The method is devised for real lattice Hamiltonians and is based on an iterative &#39;&#39;stochastic reconfiguration&#39;&#39; scheme which introduces some bias but allows a stable simulation with constant sign. The systematic reduction of this bi

Gang Su, Masuo Suzuki

By making use of some symmetry properties of the relevant Hamiltonian, two fundamental relations between the ferromagnetic magnetization and a spin correlation function are derived for the $d (=1,2,3)$-dimensional Hubbard model at finite temperatures. These can be viewed as a kind of Ward-Takahashi identities. The properties of the magnetization as a functio

P. Ao, Q. Niu

We analyze the physical processes involved in the Aharonov-Bohm (A-B) and the Aharonov-Casher (A-C) effects, showing that an incomplete A-B effect knowledge can lead a totally wrong conclusion on the A-C effect. Based on this we demonstrate that the Magnus force, the net force, is the only transverse force on a moving vortex, in analogous to the net charge i

A. G. Percus

In the traveling salesman problem, one must find the length of the shortest closed tour visiting given ``cities&#39;&#39;. We study the stochastic version of the problem, taking the locations of cities and the distances separating them to be random variables drawn from an ensemble. We consider first the ensemble where cities are placed in Euclidean space. We

Juan Carlos Chaves, Indubala I. Satija, Mauro M. Doria

We study the interplay between strong correlations and incommensurability on fermions using mean field as well as exact many-body Lanczos diagonalization techniques. In a two-dimensional parameter space, mean field phase diagram of infinite system shows a critical phase with multifractal characteristics sandwiched between a Bloch-type extended and a localize

V. Dohm

The present status of the renormalization-group (RG) predictions on the superfluid density $ρ_s$ and the specific heat $C^+$ and $C^-$ near the $λ$-line of $^4He$ is briefly reviewed. Particular attention is given to universal amplitude ratios related to these quantities. The goals of a new theory project are presented that involves higher-order calculations

James MacDonald, Margarita Hernanz, Jordi José

We investigate the evolution of cooling helium atmosphere white dwarfs using a full evolutionary code, specifically developed for following the effects of element diffusion and gravitational settling on white dwarf cooling. The major difference between this work and previous work is that we use more recent opacity data from the OPAL project. Since, in genera

Tod E. Strohmayer, William Zhang, Jean H. Swank, Nicholas E. White

We present a study of 581 Hz oscillations observed during a thermonuclear X-ray burst from the low mass X-ray binary (LMXB) 4U 1636-54 with the Rossi X-ray Timing Explorer (RXTE). We argue that the combination of large pulsed amplitudes near burst onset and the spectral evidence for localized emission during the rise strongly supports rotational modulation a

Andreas Huss, Bhuvnesh Jain, Matthias Steinmetz

We investigate the formation of virialized halos due to the gravitational collapse of collisionless matter using high-resolution N-body simulations. A variety of formation scenarios are studied, ranging from hierarchical clustering to monolithic radial collapse. The goal of these experiments was to study departures from the universal density profiles recentl

J. Magueijo

Session B.3, on physics of the early Universe, of GR15 is briefly summarized.

J. A. Ouellette, C. J. Pritchet

We have used the results of recent smoothed particle hydrodynamic simulations of colliding stars to create models appropriate for input into a stellar evolution code. In evolving these models, we find that little or no surface convection occurs, precluding angular momentum loss via a magnetically-driven stellar wind as a viable mechanism for slowing rapidly

Julian Borrill

As the Cosmic Microwave Background (CMB) radiation is observed to higher and higher angular resolution the size of the resulting datasets becomes a serious constraint on their analysis. In particular current algorithms to determine the location of, and curvature at, the peak of the power spectrum likelihood function from a general $N_{p}$-pixel CMB sky map s

I. A. Steele, I Negueruela, M. J. Coe, P. Roche

Chevalier & Ilovaisky (1998) use Hipparcos data to show that the X-ray binary systems LSI+61 303 and A0535+262 are a factor of ten closer (i.e. d = few hundred pc) than previously thought (d = 2 kpc). We present high quality CCD spectra of the systems, and conclude that the spectral types, reddening and absolute magnitudes of these objects are strongly incon

Eliot Quataert, Andrei Gruzinov

We extend and reconcile recent work on turbulence and particle heating in advection-dominated accretion flows. For approximately equipartition magnetic fields, the turbulence primarily heats the electrons. For weaker magnetic fields, the protons are primarily heated. The division between electron and proton heating occurs between $β\sim 5$ and $β\sim 100$ (w

David R. Soderblom, Jeremy R. King, Todd J. Henry

We have obtained high-resolution echelle spectra of 18 solar-type stars that an earlier survey showed to have very high levels of Ca II H and K emission. Most of these stars belong to close binary systems, but 5 remain as probable single stars or well-separated binaries that are younger than the Pleiades on the basis of their lithium abundances and H-alpha e

Walter Dehnen

(abridged) The velocity distribution f(v) of nearby stars is estimated, via a maximum- likelihood algorithm, from the positions and tangential velocities of a kinematically unbiased sample of 14369 stars observed by the HIPPARCOS satellite. f(v) shows rich structure in the radial and azimuthal motions, v_R and v_phi, but not in the vertical velocity, v_z: th

T. Boeker, A. Krabbe, J. W. V. Storey

We report on mid-infrared (MIR) continuum and line emission mapping of the nucleus of NGC 253. The data, with a resolution of 1\as.4, reveal a double-peaked arc-like [NeII] emission region. Comparison with published data shows that the [NeII] arc is centered on the nucleus of the galaxy. The brightest [NeII] source coincides with the infrared continuum peak.

A. Shearer, C. M. M. O&#39; Sullivan, A. Golden, P. V. R. Garcia

Using time resolved 2-dimensional aperture photometry we have established that the optical candidate for PSR 1509-58 does not pulse. Our pulsed upper limits (m_V = 24.3 and m_B = 25.7) put severe constraints on this being the optical counterpart. Furthermore the colours of the candidate star are consistent with a main sequence star at a distance of 2-4 kpc.

Brian Chaboyer

Lithium is an excellent tracer of mixing in stars as it is destroyed (by nuclear reactions) at a temperature around $\sim 2.5\times 10^6$ K. The lithium destruction zone is typically located in the radiative region of a star. If the radiative regions are stable, the observed surface value of lithium should remain constant with time. However, comparison of th

Torsten A. Ensslin, Yiping Wang, Biman B. Nath, Peter L. Biermann

We estimate the energy release of black hole formation to the intra-cluster medium of the Coma cluster and find that this is comparable to the present day energy content. Therefore an energetic and maybe hydrostatic influence is possible. Our calculations rely on the assumption of an universal black hole to galaxy mass ratio (more exactly: spheroidal mass co

Z. -Q. Shen, T. -S. Wan, J. M. Moran, D. L. Jauncey

We report the results of a 5-GHz southern-hemisphere snapshot VLBI observation of a sample of blazars. The observations were performed with the Southern Hemisphere VLBI Network plus the Shanghai station in 1993 May. Twenty-three flat-spectrum, radio-loud sources were imaged. These are the first VLBI images for 15 of the sources. Eight of the sources are EGRE

M. Salaris, S. Cassisi

The theoretical evaluations of the Red Giant Branch Tip (TRGB) luminosity presented in Salaris & Cassisi (1997) are extended to higher metallicities, and compared with analogous independent results recently published. The comparison between our ZAHB and TRGB distance scales for galactic globular clusters presented in Salaris & Cassisi (1997) is now supplemen

Takashi Murayama, Yoshiaki Taniguchi, Aaron S. Evans, D. B. Sanders

We present near-infrared (observed frame) spectra of the high-redshift quasar S4 0636+68 at z=3.2 which was previously thought to be one of a group of ``strong&#39;&#39; Fe II emitters [i.e., F(Fe II 4434-4684)/F(Hbeta) > 1]. Our K-band spectrum clearly shows emission lines of Hbeta and [O III]4959, 5007 as well as optical Fe II emission. Our computed value

A. Vikhlinin, B. R. McNamara, W. Forman, C. Jones

We searched for cluster X-ray luminosity and radius evolution using our sample of 200 galaxy clusters detected in the 160 deg^2 survey with the ROSAT PSPC (Vikhlinin et al. 1998, astro-ph/9803099). With such a large area survey, it is possible, for the first time with ROSAT, to test the evolution of luminous clusters, Lx > 3x10^44 erg/s, in the 0.5-2 keV ban

Charles H. Lineweaver

I present several simple figures to illustrate cosmology and structure formation in a nutshell. Then I discuss the following argument: if we assume that Omega_{Lambda} = 0 then the CMB results favor high Omega_{m} while the supernova results favor low Omega_{m}. This large inconsistency is strong evidence for the incorrectness of the Omega_{Lambda} = 0 assum

A. Vikhlinin. B. R. McNamara, W. Forman, C. Jones, H. Quintana

We present a catalog of 200 clusters of galaxies serendipitously detected in 647 ROSAT PSPC pointings covering 158 square degrees. This is one of the largest X-ray selected cluster samples, comparable in size only to the ROSAT All-Sky Survey sample of nearby clusters (Ebeling et al. 1997). We detect clusters in the inner 17.5 arcmin of the ROSAT PSPC field o

C. Wilke, S. Altmeyer, T. Martinetz

A class of models for large-scale evolution and mass extinctions is presented. These models incorporate environmental changes on all scales, from influences on a single species to global effects. This is a step towards a unified picture of mass extinctions, which enables one to study coevolutionary effects and external abiotic influences with the same means.

Edi Halyo

We calculate the dimensions of operators in three and six dimensional superconformal field theories by using the duality between these theories at large N and D=11 supergravity on $AdS_{4/7} \times S^{7/4}$. We find that for the duality relations to work the Kaluza--Klein masses given in the supergravity literature must be rescaled and/or shifted.

David Bowser-Chao, Darwin Chang, Wai-Yee Keung

We propose a model of soft CP violation in which the CP violating mechanism naturally lies only in the charged Higgs sector. The charged Higgs mechanism not only accounts for the measured value of the CP-violating parameter $ε$ but also accommodates the current limits on $ε&#39;/ε$. Our model naturally prevents tree-level Flavor-Changing Neutral Currents (FC

Michael Bershadsky, Zurab Kakushadze, Cumrun Vafa

We consider string perturbative expansion in the presence of D-branes imbedded in orbifolded space-time. In the regime where the string coupling is weak and $α&#39;\to 0$, the string perturbative expansion coincides with `t Hooft&#39;s large N expansion. We specifically concentrate on theories with d=4 and ${\cal N}=0,1,2,4$, and use world-sheet orbifold tec

Robert E. Lopez, Scott Dodelson, Andrew Heckler, Michael S. Turner

In the standard Big Bang cosmology the canonical value for the ratio of relic neutrinos to CMB photons is 9/11. Within the framework of the Standard Model of particle physics there are small corrections, in sum about 1%, due to slight heating of neutrinos by electron/positron annihilations and finite-temperature QED effects. We show that this leads to change

Frank Wilczek

I discuss the general principles underlying quantum field theory, and attempt to identify its most profound consequences. The deepest of these consequences result from the infinite number of degrees of freedom invoked to implement locality. I mention a few of its most striking successes, both achieved and prospective. Possible limitations of quantum field th

D. Bailin, G. V. Kraniotis, A. Love

The phenomenological implications of the eleven dimensional limit of $M$-theory (strongly coupled $E_8\times E_8$) are investigated. In particular we calculate the supersymmetric spectrum subject to constraints of correct electroweak symmetry breaking and the requirement that the lighest supersymmetric particle provides the dark matter of the universe. The $

Robert G. Leigh, Moshe Rozali

We discuss the large N limit of the (2,0) field theory in six dimensions. We do this by assuming the validity of Maldacena&#39;s conjecture of the correspondence between large N gauge theories and supergravity backgrounds, here $AdS_7\times S^4$. We review the spectrum of the supergravity theory and compute the spectrum of primary operators of the conformal

Christos G. Tsagas, John D. Barrow

We develop further our extension of the Ellis-Bruni covariant and gauge-invariant formalism to the general relativistic treatment of density perturbations in the presence of cosmological magnetic fields. We present detailed analysis of the kinematical and dynamical behaviour of perturbed magnetized FRW cosmologies containing fluid with non-zero pressure. We

Dieter Lust

In this article we review four-dimensional string vacua with N=2 space-time supersymmetry. In particular, we will discuss several aspects of the string-string duality between the heterotic string, compactified on $K3\times T^2$, and the type II superstring compactified on a Calabi-Yau three-fold. We investigate the massless supersymmetric spectra, showing ag

K. Le Hur

We study the usual one-dimensional Kondo lattice model (1D KLM) using the non-Abelian bosonization formalism. At half-filling, we obtain a Kondo insulator with a gap in both charge and spin excitations which varies quite linearly with the Kondo exchange $J_K$. It consists of a Spin Density Glass state, or a $q=π$ spin density wave weakly pinned by a nearly a

Mark Bowick, Arshad Momen

We study the formation of domains in a continuous phase transition with a finite-temperature quench. The model treated is the $Φ^4$ theory in two spatial dimensions with global O(2) symmetry. We investigate this using real-time thermal field theory, following Boyanovsky and collaborators, and find that domain sizes appear to be smaller than those produced in

O. Theissen, G. Gompper, D. M. Kroll

A lattice-Boltzmann model for the study of the dynamics of oil-water-surfactant mixtures is constructed. The model, which is based on a Ginzburg-Landau theory of amphiphilic systems with a single, scalar order parameter, is then used to calculate the spectrum of undulation modes of an oil-water interface and the spontaneous emulsification of oil and water af

R. Pullirsch, K. Rabitsch, T. Wettig, H. Markum

We investigate the eigenvalue spectrum of the staggered Dirac matrix in SU(3) gauge theory and in full QCD on a $6^3\times 4$ lattice. As a measure of the fluctuation properties of the eigenvalues, we study the nearest-neighbor spacing distribution $P(s)$ for various values of $β$ both in the confinement and in the deconfinement phase. In both phases except

Thibault Damour, Gilles Esposito-Farese

Binary systems comprising at least one neutron star contain strong gravitational field regions and thereby provide a testing ground for strong-field gravity. Two types of data can be used to test the law of gravity in compact binaries: binary pulsar observations, or forthcoming gravitational-wave observations of inspiralling binaries. We compare the probing

Avinash Singh, Martin Ulmke, Dieter Vollhardt

The interplay of disorder and spin-fluctuation effects in a disordered antiferromagnet is studied. In the weak-disorder regime (W \le U), while the energy gap decreases rapidly with disorder, the sublattice magnetization, including quantum corrections, is found to remain essentially unchanged in the strong correlation limit. Magnon energies and Neel temperat

E. Gedalin, A. Moalem, L. Razdolskaya

The total cross section for the pp -> pp pi^0 reaction at energies close to threshold is calculated using a covariant one-boson-exchange model, where a boson B created on one of the incoming protons is converted into a neutral pion on the second. The amplitudes for the conversion processes, B N -> N pi^0, are taken to be the sum of s, u and t-channel pole te

Mohammad Khorrami, Amir Aghamohammadi, Amir Masoud Ghezelbash

We study the logarithmic superconformal field theories. Explicitly, the two-point functions of N=1 logarithmic superconformal field theories (LSCFT) when the Jordan blocks are two (or more) dimensional, and when there are one (or more) Jordan block(s) have been obtained. Using the well known three-point fuctions of N=1 superconformal field theory (SCFT), thr

Ken Sasaki

It is shown in the framework of the operator product expansion and the renormalization group method that the twist-3 part of flavour nonsinglet spin structure function g_2(x,Q^2) obeys a simple Dokshitzer-Gribov- Lipatov-Altarelli-Parisi (DGLAP) equation in the large N_C limit even in the case of massive quarks (N_C is the number of colours). There are four

S. Bonazzola, E. Gourgoulhon, J. -A. Marck

A multi-domain spectral method for computing very high precision 3-D stellar models is presented. The boundary of each domain is chosen in order to coincide with a physical discontinuity (e.g. the star&#39;s surface). In addition, a regularization procedure is introduced to deal with the infinite derivatives on the boundary that may appear in the density fie

Hee-Won Lee, Sang-Hyeon Ahn

We compute the polarization of the Lyman alpha line photons emerging from an anisotropically expanding and optically thick medium, which is expected to operate in many Lyman alpha emitting objects including the primeval galaxy DLA~2233+131 and Lyman break galaxies. In the case of a highly optically thick medium, the escape of resonance line photons is achiev

Kenji Harada, Naoki Kawashima

The two-dimensional $S=1/2$ XY model is investigated with an extensive quantum Monte Carlo simulation. The helicity modulus is precisely estimated through a continuous-time loop algorithm for systems up to $128 \times 128$ near and below the critical temperature. The critical temperature is estimated as $T_{\rm KT} = 0.3427(2)J$. The obtained estimates for t

Changhyun Ahn, Bum-Hoon Lee

We study BPS monopoles in 4 dimensional N=4 SO(N) and $Sp(N)$ super Yang-Mills theories realized as the low energy effective theory of $N$ (physical and its mirror) parallel D3 branes and an {\it Orientifold 3 plane} with D1 branes stretched between them in type IIB string theory. Monopoles on D3 branes give the natural understanding by embedding in SU(N) th

S. B. Dubovichenko

Direct cluster disintegration and radiative capture in the pd, nd, and d3He channels are considered on the basis of potential two-cluster models. Interaction between clusters is described by potentials that, in some cases, involve forbidden states and which are fitted to the phase shifts of elastic scattering at low energies. Phase shifts and potentials of s

Marek Czachor

The nonlinear algorithms proposed recently by Abrams and Lloyd [Report No. quant-ph/9801041] are fast but make an explicit use of an arbitrarily fast unphysical transfer of information within a quantum computer. It is shown that there exists a simplification of the second Abrams-Lloyd algorithm which eliminates the unphysical effect but keeps the algorithm f

Masuo Suzuki

A general formulation of noncommutative or quantum derivatives for operators in a Banach space is given on the basis of the Leibniz rule, irrespective of their explicit representations such as the Gâteaux derivative or commutators. This yields a unified formulation of quantum analysis, namely the invariance of quantum derivatives, which are expressed by mult

E. Gedalin, A. Moalem, L. Razdolskaya

The total cross section for the $pp \to pp π^0$ reaction at energies close to threshold is calculated within the frame of a chiral perturbation theory, taking into account tree and one loop diagrams up to chiral order D=2. Two-pion loop contributions dominate $π^0$ production at threshold. The calculated cross section reproduces data, both scale and energy d

E. Bauer, A. Polls, A. Ramos

A systematic study of the influence of exchange terms in the longitudinal and transverse nuclear response to quasi-elastic (e,e&#39;) reactions is presented. The study is performed within the framework of the extended random phase approximation (ERPA), which in conjuction with a projection method permits a separation of various contributions tied to differen

H. Huber, F. Weber, M. K. Weigel

The properties of hot matter are studied in the frame of the relativistic Brueckner-Hartree-Fock theory. The equations are solved self-consistently in the full Dirac space. For the interaction we used the potentials given by Brockmann and Machleidt. The obtained critical temperatures are smaller than in most of the nonrelativistic investigations. We also cal

A. J. Buchmann, Georg Wagner, Amand Faessler

The mass and wave function of a six-quark system with quantum numbers J^P=0^-, T=0, called d&#39;, are calculated. We use a colored diquark-tetraquark cluster model for the six-quark wave function. A constituent quark model Hamiltonian with a two-body confinement potential, and residual one-gluon, one-pion, and one-sigma exchange interactions is used. The co

S. B. Dubovichenko

Central nucleon-nucleon potentials involving forbidden states are obtained for the Gaussian, exponential, and Yukawa type. The parameters of interaction are obtained by fitting the scattering phase shifts for energies up to 500 MeV, low-energy parameters, and some features of the deuteron. The deuteron form factor for low momentum transfers, the momentum dis

A. Cossidente, G. Korchmaros, F. Torres

For each proper divisor d of (r^2-r+1), r being a power of a prime, maximal curves over a finite field with r^2 elements covered by the Hermitian curve of genus 1/2((r^2-r+1)/d-1) are constructed.

Vu Ngoc San

The semi-classical study of a 1-dimensional Schrödinger operator near a non-degenerate maximum of the potential has lead Colin de Verdière and Parisse to prove a microlocal normal form theorem for any 1-dimensional pseudo-differential operator with the same kind of singularity. We present here a generalization of this result to pseudo-differential integrable

Sumit R. Das, Samir D. Mathur, P. Ramadevi

Recently a method has been developed for relating four dimensional Schwarzschild black holes in M-theory to near-extremal black holes in string theory with four charges, using suitably defined ``boosts&#39;&#39; and T-dualities. We show that this method can be extended to obtain the emission rate of low energy massless scalars for the four dimensional Schwar

Y. Jack Ng

The non-perturbative Schwinger-Dyson equation is used to show that chiral symmetry is dynamically broken in QED at weak gauge couplings when an external uniform magnetic field is present. A complete analysis of this phenomenon may shed light on the Pauli problem, namely, why $α$ = 1/137.

Ioannis Giannakis, James T. Liu, Massimo Porrati

We derive model independent, non-perturbative supersymmetric sum rules for the magnetic and electric multipole moments of any theory with N=1 supersymmetry. We find that in any irreducible N=1 supermultiplet the diagonal matrix elements of the l-multipole moments are completely fixed in terms of their off-diagonal matrix elements and the diagonal (l-1)-multi