February 1999 arXiv papers — page 5

R. Scarpa, C. M. Urry, R. Falomo, J. E. Pesce

We present HST observations of seven unusual objects from the HST ``snapshot survey'' of BL Lac objects, of which four are gravitational lens candidates. In three cases a double point sources is observed: 0033+595, with 1.58 arcsec separation, and 0502+675 and 1440+122, each with $\sim 0.3$ arcsec separation. The last two also show one or more galaxi

John Dubinski

The evolution of galaxies is driven strongly by dynamical processes including internal instabilities, tidal interactions and mergers. The cluster environment is a useful laboratory for studying these effects. I present recent results on simulations of interacting populations of spiral and elliptical galaxies in the cosmological collapse of a cluster, showing

G. Tagliaferri, S. Covino, G. Cutispoto, R. Pallavicini

We have studied the coronal X-ray emission of the recently discovered short-period eclipsing binary HD 9770 with the BeppoSAX satellite. The data from the Low Energy and Medium Energy Concentrator Spectrometers (LECS & MECS) onboard BeppoSAX allow studying the spectrum of this star from 0.1 to 8 keV, confirming that this is a very active coronal source, with

A. Kraus, A. Witzel, T. P. Krichbaum

Rapid flux density variations on timescales of the order of a day or less (Intraday Variability, IDV) in the radio regime are a common phenomenon within the blazar class. Observations with the 100m telescope of the MPIfR showed that the variations occur not only in total intensity, but also in the polarized intensity and in polarization angle. Here we presen

D. Fargion, R. Konoplich, M. Grossi, M. Khlopov

A halo model with heavy relic neutrinos N belonging to a fourth generation and their annihilations in galactic halo may explain the recent evidence of diffused gamma (GeV) radiation around galactic plane. We considered a neutrino mass in the narrow range ($M_Z/2 < m_N < M_Z$) and two main processes as source of gamma rays. A first one is ICS of ultrarelativi

Oleg Y. Gnedin, Jeremiah P. Ostriker

We study the reaction of a globular star cluster to a time-varying tidal perturbation (gravitational shock) using self-consistent N-body simulations and address two questions. First, to what extent is the cluster interior protected by adiabatic invariants. Second, how much further energy change does the postshock evolution of the cluster potential produce an

R. R. Ross, A. C. Fabian, A. J. Young

X-ray reflection spectra are an important component in the X-ray spectra of many active galactic nuclei and Galactic black hole candidates. It is likely that reflection takes place from highly ionized surfaces of the accretion disc in some cases. This can lead to strong Comptonization of the emergent iron, and other, absorption and emission features. We pres

Gavin Ramsay, Stephen Potter, David Buckley, Peter Wheatley

CP Tuc (AX J2315--592) shows a dip in X-rays which lasts for approximately half the binary orbit and is deeper in soft X-rays compared with hard X-rays. It has been proposed that this dip is due to the accretion stream obscuring the accretion region from view. If CP Tuc was a polar, as has been suggested, then the length of such a dip would make it unique am

Norman R. Trams, Jacco Th. van Loon, Albert A. Zijlstra, Cecile Loup

We describe ISO observations of the obscured Asymptotic Giant Branch (AGB) star IRAS04496-6958 in the Large Magellanic Cloud (LMC). This star has been classified as a carbon star. Our new ISOCAM CVF spectra show that it is the first carbon star with silicate dust known outside of the Milky Way. The existence of this object, and the fact that it is one of the

M. Guainazzi, G. Matt, F. Fiore

We present new results from BeppoSAX observations of reflection-dominated Seyfert galaxies, and namely: 1) the Compton-thick Seyfert 2s NGC1068 and Circinus Galaxy; 2) the Seyfert 1 NGC4051, whose nucleus was observed on May 1998 to have switched off, leaving only a residual reflection component as an echo of its past activity. Our main focus in this paper i

P. Marziani, M. D&#39;Onofrio, D. Dultzin-Hacyan, J. W. Sulentic

UGC 3995 is a close pair of spiral galaxies whose eastern component hosts a Seyfert 2 nucleus. We present a detailed analysis of this system using long slit spectroscopy and narrow (\ha + \nii) as well as broad band (B, R) imaging and an archive WFPC2 image. The component galaxies reveal surprisingly small signs of interaction considering their spatial proxi

J. J. M. in &#39;t Zand, F. Verbunt, T. E. Strohmayer, A. Bazzano

For the second time in 27 years a bright transient X-ray source has been detected coincident with the globular cluster NGC 6440. It was found to be active in August, 1998, with the Wide Field Camera and the narrow field instruments on the BeppoSAX spacecraft, and with the All-Sky Monitor and the Proportional Counter Array on the RossiXTE spacecraft. Four X-r

Russel J. White, Andrea M. Ghez, Iain N. Reid, Greg Schultz

We present spatially separated optical spectra of the components of the young hierarchical quadruple GG Tau. Spectra of GG Tau Aa and Ab (separation 0&#34;.25 ~ 35 AU) were obtained with the Faint Object Spectrograph aboard the Hubble Space Telescope. Spectra of GG Tau Ba and Bb (separation 1&#34;.48 ~ 207 AU) were obtained with both the HIRES and the LRIS s

C. Lidman, F. Courbin, G. Meylan, T. Broadhurst

We report on the spectroscopic identification and the long awaited redshift measurement of the heavily obscured, gravitationally lensed radio source PKS 1830-211, which was first observed as a radio Einstein ring. The NE component of the doubly imaged core is identified, in our infrared spectrum covering the wavelength range 1.5-2.5 microns, as an impressive

Tom Broadhurst, Xiaosheng Huang, Brenda Frye, Richard Ellis

We present a spectroscopic redshift of z=1.675 for the well-known multiply lensed system of arcs seen in the z=0.39 cluster Cl0024+16. In contrast to earlier work, we find that the lensed images are accurately reproduced by a projected mass distribution which traces the locations of the brightest cluster ellipticals, suggesting that the most significant mini

Frederick W. Kantor

A photon&#39;s observed wavelength tells an astronomical detector about the amount of position information obtained by observing that photon. This amount of position information may depend on time in a way which, to first order over distances small compared to the size of the universe, might account for the cosmological redshift.

Andres Gomberoff, Donald Marolf

The technique known as group averaging provides powerful machinery for the study of constrained systems. However, it is likely to be well defined only in a limited set of cases. Here, we investigate the possibility of using a `renormalized&#39; group averaging in certain models. The results of our study may indicate a general connection between superselectio

V. E. R. Lemes, C. A. Linhares, S. P. Sorella, L. C. Q. Vilar

The abelian Chern-Simons theory is perturbed by introducing local gauge-invariant interaction terms depending on the curvature. The computation of the correlation function of two Wilson lines for two smooth closed nonintersecting curves is reported up to four loops and is shown to be unaffected by radiative corrections. This result ensures the stability of t

Lajos Diosi, Nicolas Gisin, Walter T. Strunz

We present a consistent framework of coupled classical and quantum dynamics. Our result allows us to overcome severe limitations of previous phenomenological approaches, like evolutions that do not preserve the positivity of quantum states or that allow to activate quantum nonlocality for superluminal signaling. A `hybrid&#39; quantum-classical density is in

Igor F. Herbut

Qualitative features of the mean-field theory of superconductivity in a strongly disordered systems of fermions with short-range attraction are discussed. In this limit the effective theory is entirely bosonic, and I consider both the artificial infinite-range limit, and the more realistic case of &#34;nearest neighbor&#34; hopping of bosons between localize

Daniel F. Litim, Cristina Manuel

Based on classical transport theory, we present a general set of covariant equations describing the dynamics of mean fields and their statistical fluctuations in a non-Abelian plasma in or out-of-equilibrium. A procedure to obtain the collision integrals for the Boltzmann equation from the microscopic theory is described. As an application, we study a hot no

J. I. Collar, K. Zioutas

The C_{60} molecule exhibits a remarkable stability and inertness that leads to its survival in ancient carbonaceous rocks initially subject to the high temperatures requisite for its formation. Elementary particles having very high electronic stopping powers can similarly form C_{60} and higher fullerenes in their wake. Combined, these two features point at

T. Frederico, V. S. Timoteo, Lauro Tomio

A renormalization scheme for the nucleon-nucleon (NN) interaction based on a subtracted T-matrix equation is proposed and applied to the one-pion-exchange potential supplemented by contact interactions. The singlet and triplet scattering lengths are given to fix the renormalized strengths of the contact interactions. With only one scaling parameter ($μ$), th

M. Hasenbusch

We present a Monte Carlo study of the one-component $ϕ^4$ model on the cubic lattice in three dimensions. Leading order scaling corrections are studied using the finite size scaling method. We compute the corrections to scaling exponent $ω$ with high precision. We determine the value of the coupling $λ$ at which leading order corrections to scaling vanish. U

M. L. Bedran, E. M. de Sá, Anzhong Wang, Yumei Wu

The emission and absorption of gravitational waves and massless particles of an infinitely long straight cosmic string with finite thickness are studied. It is shown in a general term that the back reaction of the emission and absorption {\em always} makes the symmetry axis of the string singular. The singularity is a scalar singularity and cannot be removed

Yasuharu Honda, Masaki Yasue

By the use of an effective superpotential in supersymmetric quantum chromodynamics (SQCD) with N_f flavors and N_c colors of quarks for N_f>=N_c+2, the influence of soft supersymmetry (SUSY) breakings is examined to clarify dynamics of chiral symmetry breakings near the SUSY limit. In case that SQCD triggers spontaneous chiral symmetry breakings, it is possi

Kazumitsu Sakai, Masahiro Shiroishi, Junji Suzuki, Yukiko Umeno

The quantum transfer matrix (QTM) approach to integrable lattice Fermion systems is presented. As a simple case we treat the spinless Fermion model with repulsive interaction in critical regime. We derive a set of non-linear integral equations which characterize the free energy and the correlation length of $<c_j^{\dagger}c_i>$ for arbitrary particle density

L. Fatibene, M. Ferraris, M. Francaviglia, M. Raiteri

The BTZ stationary black hole solution is considered and its mass and angular momentum are calculated by means of Noether theorem. In particular, relative conserved quantities with respect to a suitably fixed background are discussed. Entropy is then computed in a geometric and macroscopic framework, so that it satisfies the first principle of thermodynamics

Yoshiharu Kawamura

We study a mechanism of symmetry transition upon compactification of a 5-dimensional field theory on $S^1/Z_2$. The transition occurs unless all components in a multiplet of a symmetry group have a common $Z_2$ parity on $S^1/Z_2$. This mechanism is applied to a reduction of SU(5) gauge symmetry in grand unified theory, and phenomenological implications are

R. P. Malik

We discuss some aspects of cohomological properties of a two-dimensional free Abelian gauge theory in the framework of BRST formalism. We derive the conserved and nilpotent BRST- and co-BRST charges and express the Hodge decomposition theorem in terms of these charges and a conserved bosonic charge corresponding to the Laplacian operator. It is because of th

N. Brenner, O. Agam, W. Bialek, R. de Ruyter van Steveninck

Statistical properties of spike trains measured from a sensory neuron in-vivo are studied experimentally and theoretically. Experiments are performed on an identified neuron in the visual system of the blowfly. It is shown that the spike trains exhibit universal behavior over short time, modulated by a stimulus-dependent envelope over long time. A model of t

P. Schmelcher, M. V. Ivanov, W. Becken

Using a Hartree-Fock mesh method and a configuration interaction approach based on a generalized Gaussian basis set we investigate the behaviour of the exchange and correlation energies of small atoms and molecules, namely th e helium and lithium atom as well as the hydrogen molecule, in the presence of a magnetic field covering the regime B=0-100a.u. In gen

W. Becken, P. Schmelcher, F. K. Diakonos

We investigate the electronic structure of the helium atom in a magnetic field b etween B=0 and B=100a.u. The atom is treated as a nonrelativistic system with two interactin g electrons and a fixed nucleus. Scaling laws are provided connecting the fixed-nucleus Hamiltonia n to the one for the case of finite nuclear mass. Respecting the symmetries of the elec

S. A. Bass, M. Hofmann, M. Bleicher, L. Bravina

We introduce a transport approach which combines partonic and hadronic degrees of freedom on an equal footing and discuss the resulting reaction dynamics. The initial parton dynamics is modeled in the framework of the parton cascade model, hadronization is performed via a cluster hadronization model and configuration space coalescence, and the hadronic phase

V. Dmitrašinović

We show how the linear &#34;low-density theorem&#34; of Drukarev and Levin can be extended to arbitrary positive integer power of the baryon density $ρ$. The n^th coefficient in the McLaurin expansion of the fermion condensate&#39;s $ρ$ dependence is the connected n-nucleon sigma term matrix element. We calculate the $O(ρ^2)$ coefficient in lowest-order pert

J. Carbonell, V. A. Karmanov

The deuteron form factors are calculated in the framework of the relativistic nucleon-meson dynamics, by means of the explicitly covariant light-front approach. The inflluence of the nucleon electromagnetic form factors is discussed. At $Q^2\leq 3$ (GeV/c)$^2$ the prediction for the structure function $A(Q^2)$ and for the tensor polarization observable $t_{2

A. Le Fevre, M. Ploszajczak, V. D. Toneev

The influence of shape of expanding and rotating source on various characteristics of the multifragmentation process is studied. The analysis is based on the extension of the statistical microcanonical multifragmentation model. The comparison with the data is done for central Xe+Sn collisions at 50 A MeV as measured by INDRA Collaboration.

Denis Lacroix, Philippe Chomaz, Sakir Ayik

A novel method is presented for implementation of the extended mean-field theory incorporating two-body collisions. At a given time, stochastic imaginary time propagation of occupied states are used to generate a convenient basis. The quantal collision terms, including memory effects, is then computed by a backward mean-field propagation of these single-part

T. Neff, H. Feldmeier, R. Roth, J. Schnack

In Fermionic Molecular Dynamics the occurrence of multifragmentation depends strongly on the intrinsic structure of the many-body state. Slater determinants with narrow single-particle states and a cluster substructure show multifragmentation in heavy-ion collisions while those with broad wave functions, which resemble more a shell-model picture, deexcite by

C. R. Brune, K. I. Hahn, R. W. Kavanagh, P. R. Wrean

We report new measurements of the total cross section for the 3H(p,n)3He reaction from threshold (Ep=1.02 MeV) to Ep=4.5 MeV. The experiment utilized specially prepared Ti-3H targets, and neutrons were detected using a 4-pi detector. A weak resonant structure due to an excited state in 4He is observed which was not seen in previous cross section measurements

Carl Mueller

Consider the stochastic partial differential equation u_t=u_{xx}+u^gamma dot{W}, where x in [0,J], dot{W}=dot{W}(t,x) is 2-parameter white noise, and we assume that the initial function u(0,x) is nonnegative and not identically 0. We impose Dirichlet boundary conditions on u. We say that u blows up in finite time, with positive probability, if there is a fin

P. P. Goulden, D. M. Jackson, A. Vainshtein

We obtain an explicit expression for the number of ramified coverings of the sphere by the torus with given ramification type for a small number of ramification points, and conjecture this to be true for an arbitrary number of ramification points. In addition, the conjecture is proved for simple coverings of the sphere by the torus. We obtain corresponding e

Hitoshi Murakami

We show an integrality of the quantum SU(2)-invariant associated with a non-trivial first cohomology class modulo two.

Richard Corrado, Bogdan Florea, Robert McNees

We compute the two and three-point correlation functions of chiral primary operators in the large N limit of the (0,2), d=6 superconformal theory. We also consider the operator product expansion of Wilson surfaces in the (0,2) theory and compute the OPE coefficients of the chiral primary operators at large N from the correlation functions of surfaces.

G. Mussardo

We discuss the determination of the lowest Form Factors relative to the trace operators of N=1 Super Sinh-Gordon Model. Analytic continuations of these Form Factors as functions of the coupling constant allows us to study a series of models in a uniform way, among these the latest model of the Roaming Series and a class of minimal supersymmetric models.

Bernard de Wit

We give a description of supermembranes in nontrivial target-space geometries. A special class are the $AdS_4\times S^7$ and $AdS_7\times S^4$ spaces that have the maximal number of 32 supersymmetries.

S. Cotsakis, V. D. Ivashchuk, V. N. Melnikov

We analyze p-brane black hole solutions with `block-orthogonal&#39; intersection rules. The post-Newtonian parameters beta and gamma corresponding to 4-dimensional section of the metric are calculated. A family of solutions with gamma=1 is singled out. Some examples of solutions (e.g. in D=11 supergravity) are considered.

D. Karakhanyan, R. Kirschner

We consider an extension of Lipatov&#39;s conjecture about the deep relation between amplitudes in the high-energy limit of QCD and XXX Heisenberg chains with non-compact spins.

B. Borasoy, B. R. Holstein

The importance of resonances for the radiative hyperon decays is examined in the framework of chiral perturbation theory. Low lying baryon resonances are included into the effective theory and tree contributions to these decays are calculated. We find significant contributions to both the parity-conserving and parity-violating decay amplitudes and a large ne

Rim Dib, Justin Khoury, C. S. Lam

The problem of restoring Froissart bound to the BFKL-Pomeron is studied in an extended leading-log approximation of QCD. We consider parton-parton scattering amplitude and show that the sum of all Feynman-diagram contributions can be written in an eikonal form. In this form dynamics is determined by the phase shift, and subleading-logs of all orders needed t

Michael Melles

The partial Higgs width $Γ(H \longrightarrow γγ)$ is important at the LHC for Higgs masses in the MSSM mass window up to 140 GeV as a relatively background free signal of a fundamental scalar. At the photon photon mode at the NLC it would be the Higgs production mechanism . Two loop QCD corrections exist for the fermionic contribution and in the case of the

R. A. Bertlmann, W. Grimus, B. C. Hiesmayr

We consider strangeness correlations of the EPR type in K^0 \bar{K}^0 pairs created in a J^{PC} = 1^{--} state as a function of time under the hypothesis that spontaneous decoherence takes place. We parameterize the degree of decoherence by a factor (1-ζ) which multiplies the quantum-mechanical interference terms occurring in the amplitudes for like and unli

S. Kretzer, M. Stratmann

Charged current charm and D meson production is studied in detail as a means of determining the unpolarized and polarized strange sea densities at HERA. All analyses are performed in next-to-leading order QCD, including a calculation of the so far unknown spin-dependent MSbar coefficient functions up to O(alpha_s). It is shown that a decent measurement is po

David H Lyth

Taking field theory seriously, inflation model-building is difficult but not impossible. The observed value of the spectral index of the adiabatic density perturbation is starting to discriminate between models, and may well pick out a unique one in the forseeable future.

Hisao Nakkagawa, Hiroshi Yokota

In this paper the phase structure of the massive $λϕ^4$ model at finite temperature ($T \neq 0$) is investigated by applying a resummation method inspired by the renormalization-group (RG) improvement to the one-loop effective potential. The resummation method a la RG-improvement is shown to work quite succesfully by resumming up systematically large correct

Wu-Sheng Dai, Xin-Heng Guo, Xue-Qian Li, Gang Zhao

The difference of τ_{_B} and τ_{_{Λ_b}} indicates the role of the light flavors. We calculate the lifetimes of B-meson and Λ_b based on the weak effective Hamiltonian while assuming the heavy baryon is constructed by a heavy b-quark and a diquark containing two light quarks. In this scenario, we use the information of the measured ratio τ_{_{Λ_b}}/τ_{_B} as

Lawrence M. Krauss, Mark Trodden

We propose a new alternative for baryogenesis which resolves a number of the problems associated with GUT and electroweak scenarios, and which may allow baryogenesis even in modest extensions of the standard model. If the universe never reheats above the electroweak scale following inflation, GUT baryon production does not occur and at the same time thermal

J. Berges

This is an introduction to the use of nonperturbative flow equations in strong interaction physics at nonzero temperature and baryon density. We investigate the QCD phase diagram as a function of temperature, chemical potential for baryon number and quark mass within the linear quark meson model for two flavors. Whereas the renormalization group flow leads t

M. Nakagawa

A brief survey of the history of the neutrino oscillation is presented. Here emphasis is laid on the topics around the first proposal of neutrino flavor oscillation by Nagoya group in 60&#39;s. Main contents are presented in my opening address &#34;Birth of Neutrino Oscillation&#34; at the NOW&#39; 98, Amsterdam, hep-ph/9811358, but added some detail of the

K. Holland

We have previously found analytically a very unusual and unexpected form of confinement in SU(3) Yang-Mills theory. This confinement occurs in the deconfined phase of the theory. The free energy of a single static test quark diverges, even though it is contained in deconfined bulk phase and there is no QCD string present. This phenomenon occurs in cylindrica

A. Alavi-Harati et. al, the KTeV Collaboration

We report on a new measurement of the decay KL -> pi0 gamma gamma by the KTeV experiment at Fermilab. We determine the KL -> pi0 gamma gamma branching ratio to be (1.68 +/- 0.07 +/- 0.08)x10**-6. Our data shows the first evidence for a low-mass gamma gamma signal as predicted by recent O(p**6) chiral perturbation calculations that include vector meson exchan

Dong Lai

This note describes fitting formulae for the gravitational waveforms generated by a rapidly rotating neutron star (e.g., newly-formed in the core collapse of a supernova) as it evolves from an initial axisymmetric configuration toward a triaxial ellipsoid.

Naresh Dadhich

By resolving the Riemann curvature relative to a unit timelike vector into electric and magnetic parts, we define a duality transformation which interchanges active and passive electric parts. It implies interchange of roles of Ricci and Einstein curvatures. Further by modifying the vacuum/flat equation we construct spacetimes dual to the Schwarzschild solut

L. Fatibene, M. Ferraris, M. Francaviglia, M. Raiteri

The BTZ black hole solution for (2+1)-spacetime is considered as a solution of a triad-affine theory (BCEA) in which topological matter is introduced to replace the cosmological constant in the model. Conserved quantities and entropy are calculated via Noether theorem, reproducing in a geometrical and global framework earlier results found in the literature

B. L. Hu

We give a summary of the status of current research in stochastic semiclassical gravity and suggest directions for further investigations. This theory generalizes the semiclassical Einstein equation to an Einstein-Langevin equation with a stochastic source term arising from the fluctuations of the energy-momentum tensor of quantum fields. We mention recent e

Valter Moretti

Some recent (1997-1998) theoretical results concerning the $ζ$-function regularization procedure used to renormalize, at one-loop, the effective Lagrangian, the field fluctuations and the stress-tensor in curved spacetime are reviewed.

Ronald Dickman

A simple reweighting scheme is proposed for Monte Carlo simulations of interacting particle systems, permitting one to study various parameter values in a single study, and improving efficiency by an order of magnitude. Unlike earlier reweighting schemes, the present approach does not require knowledge of the stationary probability distribution, and so is ap

C. L. Kane, E. J. Mele

Scanning tunneling images of carbon nanotubes frequently show electron distributions which break the local sixfold symmetry of the graphene sheet. We present a theory of these images which relates these anisotropies to the off diagonal correlations in the single particle density matrix, and allows one to extract these correlations from the observed images. T

A. Silhanek, L. Civale, S. Candia, G. Nieva

We analyze the angular dependence of the irreversible magnetization of YBa$_2$Cu$_3$O$_7$ crystals with columnar defects inclined from the c-axis. At high fields a sharp maximum centered at the tracks&#39; direction is observed. At low fields we identify a lock-in phase characterized by an angle-independent pinning strength and observe an angular shift of th

D. M. Stamper-Kurn, H. -J. Miesner, A. P. Chikkatur, S. Inouye

Quantum tunneling was observed in the decay of metastable spin domains in gaseous Bose-Einstein condensates. A mean-field description of the tunneling was developed and compared with measurement. The tunneling rates are a sensitive probe of the boundary between spin domains, and indicate a spin structure in the boundary between spin domains which is prohibit

P. R. C. Kent, R. J. Needs, G. Rajagopal

We investigate Monte Carlo energy and variance minimization techniques for optimizing many-body wave functions. Several variants of the basic techniques are studied, including limiting the variations in the weighting factors which arise in correlated sampling estimations of the energy and its variance. We investigate the numerical stability of the techniques

V. N. Narozhnyi, J. Freudenberger, V. N. Kochetkov, K. A. Nenkov

The Hall effect in LuNi_2B_2C and YNi_2B_2C borocarbides has been investigated in normal and superconducting mixed states. The Hall resistivity rho_{xy} for both compounds is negative in the normal as well as in the mixed state and has no sign reversal below T_c typical for high-T_c superconductors. In the mixed state the behavior of both systems is quite si

Subham Majumdar, M. Mahesh Kumar, R. Mallik, E. V. Sampathkumaran

The results of electrical resistivity, heat capacity and magnetic susceptibility behavior of new class of alloys, Ce_{2-x}La_{x}CoSi_{3}, are reported. The x= 0.0 alloy is mixed valent and La substitution for Ce (x= 0.25) induces linear temperature dependence of resistivity at low temperatures, an observation of relevance to the topic of non-Fermi liquid beh

V. V. Moshchalkov, L. Trappeniers, J. Vanacken

The temperature dependence of the resistivity r(T) of the novel Sr2.5Ca11.5Cu24O41 ladder compound under hydrostatic pressure of up to 8 GPa has been explained by assuming that the relevant length scale for electrical transport is given by the magnetic correlation length related to the opening of a spin-gap in a 1D even-chain spin-ladder (1D-SL). The pressur

Cristopher Moore, M. E. J. Newman

We study the four-state antiferromagnetic Potts model on the triangular lattice. We show that the model has six types of defects which diffuse and annihilate according to certain conservation laws consistent with their having a vector-valued topological charge. Using the properties of these defects, we deduce a 2+2-dimensional height representation for the m

Dingping Li, Baruch Rosenstein

Higher than the lowest Landau level contributions to magnetization and specific heat of superconductors are calculated using Ginzburg - Landau equations approach. Corrections to the excitation spectrum around solution of these equations (treated perturbatively) are found. Due to symmetries of the problem leading to numerous cancellations the range of validit

Sumathi Rao

We give a brief introduction to the phenomenon of the Fractional Quantum Hall effect, whose discovery was awarded the Nobel prize in 1998. We also explain the composite fermion picture which describes the fractional quantum Hall effect as the integer quantum Hall effect of composite fermions.

Hari M. Koduvely, Andrew Zangwill

The Stranski-Krastanov growth kinetics of undislocated (coherent) 3-dimensional islands is studied with a self-consistent mean field rate theory that takes account of elastic interactions between the islands. The latter are presumed to facilitate the detachment of atoms from the islands with a consequent decrease in their average size. Semi-quantitative agre

Daniel M. Mueth, Heinrich M. Jaeger, Sidney R. Nagel

We report on systematic measurements of the distribution of normal forces exerted by granular material under uniaxial compression onto the interior surfaces of a confining vessel. Our experiments on three-dimensional, random packings of monodisperse glass beads show that this distribution is nearly uniform for forces below the mean force and decays exponenti

Sohrab Ismail-Beigi, Tomas Arias

We present an analytical study of the spatial decay rate $γ$ of the one-particle density matrix $ρ(\vec r,\vec r&#39;)\sim\exp(-γ|\vec r-\vec r&#39;|)$ for systems described by single particle orbitals in periodic potentials in arbitrary dimensions. This decay reflects electronic locality in condensed matter systems and is also crucial for O(N) density funct

S. Prunet, A. Lazarian

In this review, we intend to present the current knowledge of the polarized emission from thermal dust in our Galaxy. We show different methods to estimate the spatial distribution statistics of this emission in the lack of any data from the diffuse ISM, and compare it to the expected CMB polarized signal. We finally show how this contaminant could be effici

Stefanie Komossa, Hartmut Schulz

We briefly review and extend our discussion of the ROSAT detection of the extraordinarily luminous (> 10^{42} erg/s) partly extended (> 30 kpc diameter) X-ray emission from the ultraluminous infrared galaxy NGC 6240. The `standard&#39;-model of starburst outflow is contrasted with alternatives and a comparison with the X-ray properties of ellipticals is perf

T. Shahbaz, R. M. Bandyopadhyay, P. A. Charles

We have obtained for the first time $K$-band infrared spectra of the soft X-ray transient V616 Mon (=A0620--00). We determine the 2-sigma upper limit to the fraction of light arising from the accretion disc to be 27 percent. The effect this has on the binary inclination, determined from modelling the infrared ellipsoidal variations is to increase it by less

Pawan Kumar, Suzanne Talon, Jean-Paul Zahn

We calculate the angular momentum transport by gravito-inertial-Alfvén waves and show that, so long as prograde and retrograde gravity waves are excited to roughly the same amplitude, the sign of angular momentum deposit in the radiative interior of the Sun is such as to lead to an exponential growth of any existing small radial gradient of rotation velocity

Pawan Kumar

NGC 1068 is one of the best studied Seyfert II galaxies, for which the blackhole mass has been determined from the Doppler velocities of water maser. We show that the standard $α$-disk model of NGC 1068 gives disk mass between the radii of 0.65 pc and 1.1 pc (the region from which water maser emission is detected) to be about 7x10$^7$ M$_\odot$ (for $α=0.1$)

A. Kogut

Improved knowledge of diffuse Galactic emission is important to maximize the scientific return from scheduled CMB anisotropy missions. Cross-correlation of microwave maps with maps of the far-IR dust continuum show a ubiquitous microwave emission component whose spatial distribution is traced by far-IR dust emission. The spectral index of this emission, beta

Stanley L. Robertson

Proof that black holes exist will likely require confirmation of the existence of event horizons. The common assumption that the mere existence of large compact masses proves the case for black holes is an unwarranted extrapolation of General Relativity into a strong-field regime where it has not been adequately tested. Neither the large compact masses of ga

Patrick M. Gilmer

Let p be an odd prime and r be relatively prime to p. Let G be a finite p-group. Suppose an oriented 3-manifold M-tilde has a free G-action with orbit space M. We consider certain Witten-Reshetikhin-Turaev SU(2) invariants w_r(M). We will give a fomula for w_r(M) in terms of the defect of M-tilde --> M and the number of elements in G. We also give a version

John McDonald

It is usually assumed that the order H^2 corrections to the SUSY-breaking mass squared terms in the early Universe must be negative in order to allow the Affleck-Dine mechanism to work. We reconsider this assumption in the context of D-term inflation models for the case where the mass squared term has a correction cH^2 with c>0. We show that, in general, the

Izumi Hachisu, Mariko Kato, Ken&#39;ichi Nomoto

As a promising channel to Type Ia supernovae (SNe Ia), we have proposed a symbiotic binary system consisting of a white dwarf (WD) and a low mass red-giant (RG), where strong winds from the accreting WD play a key role to increase the WD mass to the Chandrasekhar mass limit. Here we propose two new evolutionary processes which make the symbiotic channel to S

Raymond Brummelhuis, Mary Beth Ruskai

We consider a one-dimensional model for many-electron atoms in strong magnetic fields in which the Coulomb potential and interactions are replaced by one-dimensional regularizations associated with the lowest Landau level. For this model we show that the maximum number of electrons is bounded above by 2Z+1 + c sqrt{B}. We follow Lieb&#39;s strategy in which

Scott A. Wilde, D. C. Kent

The natural duality between &#34;topological&#34; and &#34;regular,&#34; both considered as convergence space properties, extends naturally to p-regular convergence spaces, resulting in the new concept of a p-topological convergence space. Taking advantage of this duality, the behavior of p-topological and p-regular convergence spaces is explored, with parti

David A. Krebes

We consider the ways in which a 4-tangle T inside a unit cube can be extended outside the cube into a knot or link L. We present two links n(T) and d(T) such that the greatest common divisor of the determinants of these two links always divides the determinant of the link L. In order to prove this result we give a two-integer invariant of 4-tangles. Calculat

Azad Ahmedov, Igor V. Akushevich, Eduard A. Kuraev, Philip G. Ratcliffe

Within the framework of a simple model, we study single-spin asymmetries for pion production in hadron-hadron collisions at high-energies with one hadron polarised. The asymmetries are generated via a mechanism of final (initial) state interactions. For peripheral kinematics, when the pion belongs to the fragmentation region of the polarised proton, we find

U. Cotti, A. Gutierrez-Rodriguez, A. Rosado, O. A. Sampayo

We study the possibility of detecting the neutral Higgs bosons predicted in the Minimal Supersymmetric Standard Model (h0, H0, A0), with the reactions e+ e- --> b b h0 (H0, A0), using the helicity formalism. We analyze the region of parameter space (m_A0-tan beta) where h0(H0, A0) could be detected in the limit when tan beta is large. The numerical computati

Kazuhiro Tanaka

We present a systematic study of twist-3 light-cone distribution amplitudes of vector mesons in QCD, which is based on conformal expansion. A complete set of distribution amplitudes is constructed for ρ, ω, K^* and ϕmesons, which satisfies all (exact) equations of motion and constraints from conformal expansion.

Amir H. Fatollahi

The potential between two D0-branes at rest is calculated to be a linear. Also the potential between two fast decaying D0-branes is found in agreement with phenomenological heavy-quark potentials.

R. Bulla

The zero temperature transition from a paramagnetic metal to a paramagnetic insulator is investigated in the Dynamical Mean Field Theory for the Hubbard model. The self-energy of the effective impurity Anderson model (on which the Hubbard model is mapped) is calculated using Wilson&#39;s Numerical Renormalization Group method. Results for quasiparticle weigh

F. Pfeiffer, H. Rieger

The vortex glass model for a disordered high-T_c superconductor in an external magnetic field is studied in the strong screening limit. With exact ground state (i.e. T=0) calculations we show that 1) the ground state of the vortex configuration varies drastically with infinitesimal variations of the strength of the external field, 2) the minimum energy of gl

M. Kubota, H. Fujioka, K. Hirota, K. Ohoyama

Comprehensive neutron-powder diffraction and Rietveld analyses were carried out to clarify the relation between the crystal and magnetic structures of La2-2xSr1+2xMn2O7 (0.30 =< x =< 0.50). The Jahn-Teller (JT) distortion of Mn-O6 octahedra, i.e., the ratio of the averaged apical Mn-O bond length to the equatorial Mn-O bond length, is Delta_JT=1.042(5) at x=