arXiv papers from May 1996

Andrew F. Heckler, Edward W. Kolb

We propose a strategy for searching for isolated stellar mass black holes in the solar neighborhood with the Sloan Digital Sky Survey. Due to spherical accretion of the inter-stellar medium and the ambient magnetic field, an isolated black hole is expected to emit a blended, thermal synchrotron spectrum with a roughly flat peak from the optical down to the f

Balasubramanian Krishnan, U. M. Heller, V. K. Mitrjushkin, M. Mueller-Preussker

We investigate a model of a U(1)-Higgs theory on the lattice with compact gauge fields but completely suppressed (elementary) monopoles. We study the model at two values of the quartic Higgs self-coupling, a strong coupling, $\lambda = 3.0$, and a weak coupling, $\lambda=0.01$. We map out the phase diagrams and find that the monopole suppression eliminated t

Chung-Pei Ma

This paper presents simple analytic approximations to the linear power spectra, linear growth rates, and rms mass fluctuations for both components in a family of cold+hot dark matter (CDM+HDM) models that are of current cosmological interest. The formulas are valid for a wide range of wavenumber, neutrino fraction, redshift, and Hubble constant: $k\lo 10\,h$

Andrew R. Golding, Yves Schabes

This paper addresses the problem of correcting spelling errors that result in valid, though unintended words (such as ``peace'' and ``piece'', or ``quiet'' and ``quite'') and also the problem of correcting particular word usage errors (such as ``amount'' and ``number'', or ``among'' and ``between''). Such corrections require contextual information and are no

M. Guertler, E. -M. Ilgenfritz, J. Kripfganz, H. Perlt

We study the electroweak phase transition by lattice simulations of an effective 3--dimensional theory, for a Higgs mass of about 70 GeV. Exploiting, among others, a variant of the equal weight criterion of phase equilibrium, we obtain transition temperature, latent heat and surface tension, and compare with M_H approx 35 GeV. In the broken phase masses and

Suzhou Huang

A general condition for the self-consistency of a semiclassical approximation to a given system is suggested. It is based on the eigenvalue distribution of the relevant Hessian evaluated at the streamline configurations (configurations that almost satisfy the classical equations of motion). The semiclassical approximation is consistent when there exists a ga

J. W. Brockway, E. D. Carlson, G. G. Raffelt

Pseudoscalar particles $\phi$ usually couple electromagnetically by an interaction of the form $\frc14 g \phi F {\widetilde F}$, allowing them to convert to photons in the presence of magnetic fields. Notably, new low-mass pseudoscalars emitted from supernova (SN) 1987A would have been converted to $\gamma$-rays in the intervening magnetic field of the galax

D. W. Bliss, K. Hornbostel, G. P. Lepage

We compute the critical temperature $T_c$ for the deconfinement transition of pure QCD on coarse lattices, with $N_t = 2, 3, 4$, and lattice spacings from .33 fm to .15 fm. We employ a perturbatively improved gluon action designed to remove order $a^2$ and $\alpha_s a^2$ errors. We find that $T_c$ in units of the charmonium 1P--1S splitting and the torelon m

E. Giallongo, S. Charlot, S. Cristiani, S. D'Odorico

We present deep BVrI multicolor photometry in the field of the quasar BR1202-07 (z_{em}=4.694) aimed at selecting field galaxies at z>4. We compare the observed colors of the galaxies in the field with those predicted by spectral synthesis models including UV absorption by the intergalactic medium and we define a robust multicolor selection of galaxies at z>

F. Schmid, D. Johannsmann, A. Halperin

A tilting phase transition is predicted for systems comprising rod like molecules which are irreversibly grafted to a flat surface, so that the non interacting rods are perpendicularly oriented. The transition is controlled by the grafting density $\rho$. It occurs as $\rho$ increases as a result of the interplay between two energies. Tilt is favoured by the

Kimyeong Lee, Erick J. Weinberg, Piljin Yi

We use the multimonopole moduli space as a tool for studying the properties of BPS monopoles carrying nonabelian magnetic charges. For configurations whose total magnetic charge is purely abelian, the moduli space for nonabelian breaking can be obtained as a smooth limit of that for a purely abelian breaking. As the asymptotic Higgs field is varied toward on

T. Sakai, D. Poilblanc, D. J. Scalapino

The formation of hole pairs in the planar t-J model is studied in the presence of independent {\it dynamic} vibrations of the in-plane oxygen atoms. In-plane (breathing modes) and out-of-plane (buckling modes) displacements are considered. We find strong evidences in favor of a stabilization of the two hole bound pair by out-of-plane vibrations of the in-pla

L. Burakovsky, L. P. Horwitz, W. C. Schieve

The identification of problematic meson states as the members of the quark model $q\bar{q}$ nonets by using a hadronic resonance spectrum is discussed. The results favor the currently adopted $q\bar{q}$ assignments for the axial-vector, tensor, and 1 $^3F_4$ $J^{PC}=4^{++}$ meson nonets, and suggest a new $q\bar{q}$ assignment for the scalar meson nonet whic

Michael Stone

The notion of spectral flow has given new insight into the motion of vortices in superfluids and superconductors. For a BCS superconductor the spectrum of low energy vortex core states is largely determined by the geometric optics limit of Andreev reflection. We use this to follow the evolution of the states when a stationary vortex is immersed in a transpor

R. Banerjee, P. Mukherjee

We discuss a novel method of obtaining the fractional spin of abelian and nonabelian Chern-Simons vortices. This spin is interpreted as the difference between the angular momentum obtained by modifying Schwinger's energy momentum tensor by the Gauss constraint, and the canonical (Noether) angular momentum. It is found to be a boundary term depending only on

Roberto Longo

A local formula for the dimension of a superselection sector in Quantum Field Theory is obtained as vacuum expectation value of the exponential of the proper Hamiltonian. In the particular case of a chiral conformal theory, this provides a local analogue of a global formula obtained by Kac and Wakimoto within the context of representations of certain affine

Chris Dove, Euan J. Squires

A model of spontaneous wavefunction collapse, which is explicitly local and Lorentz-invariant, is defined. Some of the predictions of the model for specific experimental situations are derived. It is shown that, although incompatible collapses, e.g. on opposite sides of an EPR-type of experiment, can occur, they will not persist in time and that eventually o

J. Ambjorn, A. Sedrakyan

We show that the measure of the three dimensional Nambu-Goto string theory has a simple decomposition as a measure on two parameter group of induced area-preserving transformations of the immersed surface and a trivial measure for the area of the surface.

Jan Ryckebusch

A factorized and analytical form for the A($\gamma$,pp) and A(e,e$'$pp) cross section is proposed. In the suggested scheme the two-proton knockout cross sections can be directly analyzed in terms of the ground-state correlation functions. Central, spin-spin and tensor correlations are considered. In the longitudinal channel, the (e,e$'$pp) cross section is p

Harald Anlauf, Panagiotis Manakos, Thorsten Ohl, Hans Dieter Dahmen

We describe the new version of the Monte Carlo event generator WOPPER for four fermion production through W-pairs including resummed leading logarithmic QED radiative corrections. Among the new features included are singly resonant background diagrams and anomalous triple gauge boson couplings.

Ting Yu

We study and compare the decoherent histories approach, the environment-induced decoherence and the localization properties of thesolutions to the stochastic Schr\"{o}dinger equation in quantum jump simulationand quantum state diffusion approaches, for a quantum two-level system model. We show, in particular, that there is a close connection between the deco

H. M. Asatrian, G. K. Yeghiyan

The Higgs boson mass problem is considered in the next-to-minimal supersymmetric standard model for the case of the spontaneous CP violation. The renormalization group equations for the gauge, Yukawa and scalar coupling constants, the effective Higgs potential and lower experimental bounds on Higgs boson and chargino masses are analyzed. The restrictions on

Wen-Xiu Ma, Benno Fuchssteiner

A kind of Bargmann symmetry constraints involving Lax pairs and adjoint Lax pairs is proposed for soliton hierarchy. The Lax pairs and adjoint Lax pairs are nonlinearized into a hierarchy of commutative finite dimensional integrable Hamiltonian systems and explicit integrals of motion may also be generated. The corresponding binary nonlinearization procedure

A. Buonanno, M. Maggiore, C. Ungarelli

We compute the spectrum of relic gravitons in a model of string cosmology. In the low- and in the high-frequency limits we reproduce known results. The full spectrum, however, also displays a series of oscillations which could give a characteristic signature at the planned LIGO/VIRGO detectors. For special values of the parameters of the model the signal rea

R. L. Jaffe

Data on the nucleon spin structure suggests that the $u$ (and $d$) quark distributions in the $\Lambda$ hyperon may be polarized. If this correlation carries over into fragmentation, then the study of polarized $\Lambda$'s in the current fragmentation region of deep inelastic lepton scattering will be a sensitive probe of nucleon spin structure. $\Lambda$ pr

A. Muendel, G. Baur

We investigate effects of strong interactions on the electromagnetic dissociation of nuclei in heavy ion collisions. We start from the eikonal approach to the equivalent photon method to describe the electromagnetic contributions to the cross section of peripheral collisions. We summarize some results of this approach and characterize recent experiments in "

A. Wirth, L. Biferale

A shell-model version of Kraichnan's (1994 {\it Phys. Rev. Lett. \bf 72}, 1016) passive scalar problem is introduced which is inspired from the model of Jensen, Paladin and Vulpiani (1992 {\it Phys. Rev. A\bf 45}, 7214). As in the original problem, the prescribed random velocity field is Gaussian, delta-correlated in time and has a power-law spectrum $\propt

T. Xiang, J. M. Wheatley

A novel interplay between d-wave superconducting order parameter symmetry and the underlying Cu 3d orbital based electronic structure of Copper-Oxides leads to a striking anisotropy in the superfluid response of these systems. In clean tetragonal materials the c-axis penetration depth increases as T^5 at low temperature T, in contrast to linear T behavior in

B. Ancochea, A. Bramon, R. Muñoz-Tapia, M. Nowakowski

We analyze $K^0-\bar{K^0}$ oscillations in space in terms of propagating wave packets with coherent $K_S$ and $K_L$ components. The oscillation probabilities $P_{K^0 \to K^0} (x)$ and $P_{K^0 \to \bar{K^0}} (x)$ depending only on the distance $x$, are defined through the time integration of a current density $j(x,t)$ . The definition is such that it coincide

A. I. Davydychev, P. Osland, O. V. Tarasov

We review the calculation of one-loop contributions to the three-gluon vertex, for arbitrary (off-shell) external momenta, in arbitrary covariant gauge and in arbitrary space-time dimension. We discuss how one can get the results for all on-shell limits of interest directly from the general off-shell expression.

Mario Atance, José Luis Cortés

The structure of the renormalization group equations for the low energy effective theory of gravity coupled to a scalar field is presented. An approximate solution to these equations with a finite number of independent renormalized parameters can be found when the mass scale characteristic of the fluctuations in the geometry is much smaller than the Planck m

M. C. Bento, O. Bertolami

We study the possibility of obtaining inflationary solutions from S-dual superstring potentials. We find, in particular, that such solutions occur at the core of domain walls separating degenerate minima whose positions differ by modular transformations.

Manuel Drees, R. M. Godbole, Monoranjan Guchait, Sreerup Raychaudhuri

Stop contributions to radiative corrections to R_b and the top quark decay are analysed over the relevant MSSM parameter space. One sees a 30 % increase in the former along with a similar drop in the latter in going from the higgsino dominated to the mixed region. Consequently one can get a viable SUSY contribution to R_b within the constraint of the top qua

M. Bleicher, N. Amelin, S. A. Bass, M. Brandstetter

The microscopic phasespace approach URQMD is used to investigate the stopping power and particle production in heavy systems at SPS and RHIC energies. This framework bridges with one model consistently the entire available range of energies from below SIS to CERN, even for the heaviest system Pb+Pb. URQMD is a hadronic transport model based on the propagatio

C. Rascon, L. Mederos, G. Navascues

We present the first theoretical approach to the angular-average of the two-body correlation function $\tilde g(r)$ for simple solids. It is based on three sum rules for $\tilde g(r)$: the compressibility and virial equations and the normalization. We apply the theory to determine this correlation function for the case of the FCC solid phase of hard spheres.

V. V. Kiselev

The two-particle decays of B_c^+ to psi pi^+(rho^+) and B_c^+ to eta_c pi^+(rho^+) are considered in a way taking into account a soft binding of quarks in the heavy quarkonia and a hard gluon exchange between the constituents at large recoil momenta of psi(eta_c). An approximate double enhancement of the amplitudes is found because of the nonspectator t-chan

J. S. Prakash

An explicit and simple correspondence, between the basis of the model space of $SU(3)$ on one hand and that of $SU(2)\otimes SU(2)$ or $SO(1,3)$ on the other, is exhibited for the first time. This is done by considering the generating functions for the basis vectors of these model spaces.

Y. B. Saakian

Finite size effects in the multicriticity point and boundaries between phases are calculated. There are anomalous large finite size effects on the boundary of ferromagnetic phase with paramagnetic or spin-glass. Multicriticity point is not giving global minimum for the finite size corrections of free energy.

A. Perali, C. Castellani, C. Di Castro, M. Grilli

We investigate the symmetry of the superconducting order parameter in the proximity of a phase-separation or of an incommensurate charge-density-wave instability. The attractive effective interaction at small or intermediate transferred momenta is singular near the instability. This strongly $q$-dependent interaction, together with a residual local repulsion

Reinhold Egger, Hermann Grabert

The bosonization technique to describe correlated electrons in a one-dimensional quantum wire containing impurities is extended to include an applied voltage source. The external reservoirs are shown to lead to a boundary condition for the boson phase fields. We use the formalism to investigate the channel conductance, electroneutrality, and charging effects

Akio Hosoya, Ichiro Oda

We study a behavior of quantum generalized affine parameter (QGAP), which has been recently proposed by one of the present authors, near the singularity and the event horizon in three and four spacetime dimensions in terms of a minisuperspace model of quantum gravity. It is shown that the QGAP is infinite to the singularity while it remains finite to the eve

N. Sakai

Supersymmetry and Supersymmetric models are reviewed. Lecture given at the KOSEF-JSPS Winter School, Recent Developments in Particle and Nuclear Theory February 21- March 2, 1996,

Tohru Eguchi, Kentaro Hori, Chuan-Sheng Xiong

We discuss how the theory of quantum cohomology may be generalized to ``gravitational quantum cohomology'' by studying topological sigma models coupled to two-dimensional gravity. We first consider sigma models defined on a general Fano manifold $M$ (manifold with a positive first Chern class) and derive new recursion relations for its two point functions. W

Jon D. Pelletier

The power spectrum, $S$, of horizontal transects of plankton abundance are often observed to have a power-law dependence on wavenumber, $k$, with exponent close to -2: $S(k)\propto k^{-2}$ over a wide range of scales. I present power spectral analyses of aircraft lidar measurements of phytoplankton abundance from scales of 1 to 100 km. A power spectrum $S(k)

Gary T. Horowitz, Donalf Marolf

We consider a family of solutions to string theory which depend on arbitrary functions and contain regular event horizons. They describe six dimensional extremal black strings with traveling waves and have an inhomogeneous distribution of momentum along the string. The structure of these solutions near the horizon is studied and the horizon area computed. We

S. Kumano

In order to test the NMC finding of flavor asymmetry $\overline u-\overline d$ in the nucleon, existing Drell-Yan data for the tungsten target are often used. However, we have to be careful in comparing nuclear data with the nucleon ones. We investigate whether there exists significant nuclear modification of the $\overline u - \overline d$ distribution in a

G. M. Kavoulakis, Yia-Chung Chang, Gordon Baym

Three experimental observations on 1s-excitons in Cu$_2$O are not consistent with the picture of the exciton as a simple hydrogenic bound state: the energies of the 1s-excitons deviate from the Rydberg formula, the total exciton mass exceeds the sum of the electron and hole effective masses, and the triplet-state excitons lie above the singlet. Incorporating

M. Villar-Martin, L. Binette

We investigate here the origin of the gas observed in extended emission line regions surrounding AGNs. We use the technique of calcium depletion as a test to prove or disprove the existence of dust in such a gas in order to discriminate between two main theories: (1) a cooling process from a hotter X-ray emitting phase surrounding the galaxy, (2) merging or

C. Lobo, A. Biviano, F. Durret, D. Gerbal

Using our catalogue of V$_{26.5}$ isophotal magnitudes for 6756 galaxies in a region covering 60~$\times$~25~arcmin$^2$ in the center of the Coma cluster, plus 267 galaxies in a region of 9.7~$\times$~9.4~arcmin$^2$ around NGC~4839, we derive the luminosity function in the magnitude range 13.5$\leq V_{26.5} <$ 21.0 (corresponding to the absolute magnitude ra

A. Ballestrero, V. A. Khoze, E. Maina, S. Moretti

An important issue in the direct reconstruction method of determining the $W$ mass from $q\bar q Q\bar Q$ events at LEP2 concerns the impact of the relatively unknown QCD interconnection effects. It has been suggested that a study of `short string' states, in which colour singlet states are formed from $q \bar Q $ and $Q\bar q$ pairs with small phase--space

Albion Lawrence

We describe the ${\cal{O}}({\alpha'}^0)$ constraints on the target space geometry of the $N=(2,1)$ heterotic superstring due to the left-moving $N=1$ supersymmetry and $U(1)$ currents. In the fermionic description of the internal sector supersymmetry is realized quantum mechanically, so that both tree-level and one-loop effects contribute to the order ${\cal

Wayne Hu, David N. Spergel, Martin White

Causal seed models, such as cosmological defects, generically predict a distinctly different structure to the CMB power spectrum than inflation, due to the behavior of the perturbations outside the horizon. We provide a general analysis of their causal generation from isocurvature initial conditions by analyzing the role of stress perturbations and conservat

J. Distler, B. Greene, D. Morrison

In contrast to the familiar (2,2) case, the singularities which arise in the (0,2) setting can be associated with degeneration of the base Calabi-Yau manifold {\it and/or}\/ with degenerations of the gauge bundle. We study a variety of such singularities and give a procedure for resolving those which can be cured perturbatively. Among the novel features whic

Eli Hawkins

A version of foliated spacetime is constructed in which the spatial geometry is described as a time dependent noncommutative geometry. The ADM version of the gravitational action is expressed in terms of these variables. It is shown that the vector constraint is obtained without the need for an extraneous shift vector in the action.

D. Kharzeev, H. Satz, A. Syamtomov, G. Zinovjev

We extend a recent sum rule calculation for inelastic quarkonium-hadron interactions to realistic parton distribution functions; we also include finite target-mass corrections. Both modifications are shown to have no significant effect on the resulting cross section behaviour but the performed analysis gives useful insights on the sum-rule approach in genera

Dominic Mayers

The claim of quantum cryptography has always been that it can provide protocols that are unconditionally secure, that is, for which the security does not depend on any restriction on the time, space or technology available to the cheaters. We show that this claim does not hold for any quantum bit commitment protocol. Since many cryptographic tasks use bit co

Roland Fehrenbacher

The one-dimensional (1D) $t$-$J$ Holstein model is studied by exact diagonalization of finite rings using a variational approximation for the phonon states. Due to renormalization effects induced by the phonons, for intermediate electron-phonon coupling, the phase separation (PS) boundary, and with it the region of dominating superconducting fluctuations is

Bhuvnesh Jain

The stable clustering hypothesis is a key analytical anchor on the nonlinear dynamics of gravitational clustering in cosmology. It states that on sufficiently small scales the mean pair velocity approaches zero, or equivalently, that the mean number of neighbours of a particle remains constant in time at a given physical separation. In this paper we use N-bo

Alexander Vilenkin, Serge Winitzki

The problem of making predictions in eternally inflating universe that thermalizes by bubble nucleation is considered. A recently introduced regularization procedure is applied to find the probability distribution for the ensemble of thermalized bubbles. The resulting probabilities are shown to be independent of the choice of the time parametrization. This f

Zurab Kakushadze, S. -H. Henry Tye

The construction of a supersymmetric $SO(10)$ grand unification with 5 left-handed and 2 right-handed families in the four-dimensional heterotic string theory is presented. The model has one $SO(10)$ adjoint Higgs field. The $SO(10)$ current algebra is realized at level 3.

Gia Dvali

Supersymmetric theories often include the non-compact directions in the field space along which the tree level potential grows only up to a certain limited value (determined by the mass scale of the theory) and then stays constant for the arbitrarily large expectation value of the field parametrizing the direction. Above the critical value, the tree-level cu

Nikolaos A Batakis

The complexified gauging of the de Sitter group gives a unified theory for the electroweak and gravitational interactions. The standard spectrum for the electroweak gauge bosons is recovered with the correct mass assignments, following a spontaneous breaking of the gauge symmetry imposed by the geometry. There is no conventional Higgs sector. New physics is

S. Bonazzola, E. Gourgoulhon

Contents: 1. Introduction 2. Spontaneous symmetry breaking 2.1 Review of classical results about Maclaurin/Jacobi ellipsoids 2.2 Spontaneous breaking of symmetry: a general phenomenom 2.3 Previous results for compressible Newtonian stars 2.4 Generation of gravitational waves 2.5 Finding the equilibrium configurations of a rotating star in the Newtonian regim

D. Rainwater, R. Szalapski, D. Zeppenfeld

The purely electroweak process $qq\to qqZ$ (via $t$-channel $\gamma/Z$ or $W$ exchange) provides a copious and fairly clean source of color-singlet exchange events in $pp$ collisions at the LHC. A judicious choice of phase-space region allows the suppression of QCD backgrounds to the level of the signal. The color-singlet-exchange signal can be distinguished

James Coleman

A recently-developed theory of quantum general relativity provides a propagator for free-falling particles in curved spacetimes. These propagators are constructed by parallel-transporting quantum states within a quantum bundle associated to the Poincare frame bundle. We consider such parallel transport in the case that the spacetime is a classical Robertson-

NLC ZDR Design Group, NLC Physics Working Group, S. Kuhlman

We present the current expectations for the design and physics program of an e+e- linear collider of center of mass energy 500 GeV -- 1 TeV. We review the experiments that would be carried out at this facility and demonstrate its key role in exploring physics beyond the Standard Model over the full range of theoretical possibilities. We then show the feasibi

Friedemann Brandt, Jordi París

We develop an efficient technique to compute anomalies in supersymmetric theories by combining the so-called nonlocal regularization method and superspace techniques. To illustrate the method we apply it to a four dimensional toy model with potentially anomalous N=1 supersymmetry and prove explicitly that in this model all the candidate supersymmetry anomali

Joshua Goodman

Many different metrics exist for evaluating parsing results, including Viterbi, Crossing Brackets Rate, Zero Crossing Brackets Rate, and several others. However, most parsing algorithms, including the Viterbi algorithm, attempt to optimize the same metric, namely the probability of getting the correct labelled tree. By choosing a parsing algorithm appropriat

M. T. Peña, Franz Gross, Yohanes Surya

We discuss the two-pion exchange potential which emerges from a box diagram with one nucleon (the spectator) restricted to its mass shell, and the other nucleon line replaced by a subtracted, covariant $\pi N$ scattering amplitude which includes $\Delta$, Roper, and $D_{13}$ isobars, as well as contact terms and off-shell (non-pole) dressed nucleon terms. Th

P. Bowcock, A. Taormina

N=2 noncritical strings are closely related to the $\Slr/\Slr$ Wess-Zumino- Novikov-Witten model, and there is much hope to further probe the former by using the algebraic apparatus provided by the latter. An important ingredient is the precise knowledge of the $\hslc$ representation theory at fractional level. In this paper, the embedding diagrams of singul

R. Frezzotti, M. Masetti, R. Petronzio

We perform an extrapolation from negative to positive flavour numbers of full QCD lattice estimates of the $\eta'$ mass. The extrapolations are carried out by keeping $\rho$ and $\pi$ masses at fixed values. We find an $\eta'$ -- $\pi$ splitting which shows a flavour dependence consistent with the Witten Veneziano formula based on the $U(1)$ anomaly. The qua

Yuri V. Kovchegov

We consider a very large ultra-relativistic nucleus. Assuming a simple model of the nucleus and weak coupling we find a classical solution for the gluon field of the nucleus and construct the two-dimensional color charge density for McLerran-Venugopalan model out of it. We prove that the density of states distribution, as a function of color charge density,

M. Moriconi, K. Schoutens

We study two-dimensional integrable $N=1$ supersymmetric theories (without topological charges) in the presence of a boundary. We find a universal ratio between the reflection amplitudes for particles that are related by supersymmetry and we propose exact reflection matrices for the supersymmetric extensions of the multi-component Yang-Lee models and for the

S. Bellucci, V. Faraoni

The available tests of the equivalence principle constrain the mass of the Higgs-like boson appearing in extended supergravity theories. We determine the constraints imposed by high precision experiments on the antigravity fields (gravivector and graviscalar) arising from $N=2,8$ supergravity.

Y. M. Vilk

The conditions for the precursors of antiferromagnetic bands in cuprate superconductors are studied using weak-to-intermediate coupling approach. It is shown that there are, in fact, three different precursor effects due to the proximity to antiferromagnetic instability: i) the shadow band which associated with new pole in the Green's function ii) the disper

Arjendu K. Pattanayak, Paul Brumer

Phase space representations of the dynamics of the quantal and classical cat map are used to explore quantum--classical correspondence in a K-system: as $\hbar \to 0$, the classical chaotic behavior is shown to emerge smoothly and exactly. The quantum dynamics near the classical limit displays both exponential separation of adjacent distributions and long ti

Luis C. Ho, Alexei V. Filippenko

Recent high-resolution observations with the Hubble Space Telescope (HST) reveal that star clusters of extraordinary luminosity and compactness are commonly found in a variety of starburst systems. There has been much speculation that these clusters represent present-day analogs of young globular clusters. Using the HIRES echelle spectrograph on the Keck 10

Francesco Fucito, Gabriele Travaglini

Using instanton calculus we check, in the weak coupling region, the nonperturbative relation $$ <\Tr\phi^2>=i\pi\left(\cf-{a\over 2} {\partial\cf\over\partial a}\right)$$ obtained for a N=2 globally supersymmetric gauge theory. Our computations are performed for instantons of winding number k, up to k=2 and turn out to agree with previous nonperturbative res

Boris Blok, Igor Halperin

We discuss a possible generation of color suppressed B-decays amplitudes through a soft final state interaction. As a typical example, we consider in detail the decay $ \bar{B}^{0} \rightarrow D^{0} \pi^{0} $ (and also $ \bar{B}^{0} \rightarrow 2 \pi^{0} $). We show that in the approximation of the two particle unitarity and at zero order in $ \alpha_{s} $ t

J"urgen Fuchs, Urmie Ray, Christoph Schweigert

To any symmetry of the Cartan matrix of a Generalized Kac-Moody (GKM) algebra we associate a family of automorphisms of the algebra which act in a natural way on the modules of the GKM algebra. We introduce the twining character of a module which is obtained by inserting the action of such an automorphism into the trace that appears in the ordinary character

Georges Bouzerar, Didier Poilblanc

Persistent currents in disordered mesoscopic rings threaded by a magnetic flux are calculated using exact diagonalization methods in the one-dimensional (1D) case and self-consistent Hartree-Fock treatments for two dimensional (2D) systems. For multichannel systems, a comparative study between models of spinless or spinfull (Hubbard) fermions has been done.

P. M. Ferreira, I. Jack, D. R. T. Jones

We present the supersymmetric standard model three-loop $\beta$-functions for gauge and Yukawa couplings and consider the effect of three-loop corrections on the standard running coupling analyses.

K. Behrndt, E. Bergshoeff

In four dimensions there are 4 different types of extremal Maxwell/scalar black holes characterized by a scalar coupling parameter $a$ with $a=0,1/\sqrt{3} , 1 , \sqrt{3}$. These black holes can be described as intersections of ten--dimensional non-singular Ramond-Ramond objects, i.e.~$D$-branes, waves and Taub-NUT solitons. Using this description it can be

G. Parzen

A treatment is given of the orbit dynamics for linear unstable motion that allows for the zeros in the beta function and makes no assumptions about the realness of the betatron and phase functions. The phase shift per turn is shown to be related to the beta function and the number of zeros the beta function goes through per turn. The solutions of the equatio

E. T. Akhmedov

The four dimensional Abelian Higgs model with monopoles and $\Theta$-term is considered in the limit of the large mass of the higgs boson. We show that for $\Theta=2 \pi$ the theory is equivalent, at large distances, to summation over all possible world-sheets of fermionic strings with Dirichlet type boundary conditions on string coordinates.

Amitava Datta, Aseshkrishna Datta, Sreerup Raychaudhuri

Currently popular search strategies for supersymmetric particles may be significantly affected due to relatively light sneutrinos which decay dominantly into invisible channels. In certain cases the second lightest neutralino may also decay invisibly leading to two extra carriers of missing energy (in addition to the lightest supersymmetric particle (LSP)) -

I. I. Balitsky, V. M. Braun, Y. Koike, K. Tanaka

We prove that the twist-3 chiral-odd parton distributions obey simple Gribov-Lipatov-Altarelli-Parisi evolution equations in the limit $N_c\to\infty$ and give analytic results for the corresponding anomalous dimensions. To this end we introduce an evolution equation for the corresponding three-particle twist-3 parton correlation functions and find an exact a

A. Acus, E. Norvaišas, D. O. Riska

The representations of general dimension are constructed for the $SU(2)$ Skyrme model, treated quantum mechanically {\it ab initio. } This quantum Skyrme model has a negative mass term correction, that is not present in the classical Hamiltonian. The magnitude of the quantum mechanical mass correction increases with the dimension of the representation of the

I. Bediaga, C. Göbel, R. Méndez--Galain

We claim that the non-resonant contribution to non-leptonic charm meson decays may not be constant in the phase space of the reaction. We argue that this can be relevant for any weak reaction. We discuss in detail the decay $D^+ \to K^- \pi^+ \pi^+$.

P. A. Henning

The description of thermal or non-equilibrium systems necessitates a quantum field theory which differs from the usual approach in two aspects: 1.The Hilbert space is doubled; 2.Stable quasi-particles do not exist in interacting systems. A mini-review of these two aspects is given from a practical viewpoint including two applications. For thermal states it i

G. Wanders

An explicitly crossing-symmetric decomposition of the pion-pion scattering amplitudes into low- and high-energy components is established. The high-energy components are entirely determined by absorptive parts at high energies. With the exception of the two leading-order parameters, all the parameters appearing in the one- and two-loop chiral amplitudes are

G. Cvetic

We study Higgs condensation in the top-mode standard model at the next-to-leading (NTL) order in 1/Nc, by calculating the effective potential as a function of a hard mass term of the top quark. We include the effects of the top and bottom quarks, all the scalars, and the leading QCD effects, but not the effects of the transverse components of the electroweak

Ch. Schaab, D. Voskresensky, A. D. Sedrakian, F. Weber

Neutrino emission from the dense hadronic component in neutron stars is subject to strong modifications due to collective effects in the nuclear medium. We implement new estimates of the neutrino emissivities of two processes operating in the nuclear medium into numerical cooling simulations of neutron stars. The first process is the modified Urca process, f

Hitoshi Konno

Free field representation of level-$k (\not=0,-2)$ Yangian double ${\cal D}Y(sl_2)_k$ and a corresponding deformation of Wakimoto modules are presented. We also realize two types of vertex operators intertwining these modules.

J. A. de Azcarraga, J. C. Perez Bueno

It is shown that the non-trivial cocycles on simple Lie algebras may be used to introduce antisymmetric multibrackets which lead to higher-order Lie algebras, the definition of which is given. Their generalised Jacobi identities turn out to be satisfied by the antisymmetric tensors (or higher-order `structure constants') which characterise the Lie algebra co

V. Barone, T. Calarco, A. Drago

The transverse polarization distribution of quarks $h_1(x)$ is computed in a confinement model, the chiral chromodielectric model. The flavor structure of $h_1$, its $Q^2$ evolution and Soffer's inequality are studied. The Drell--Yan double transverse asymmetry $A_{TT}$ is evaluated and found to be one order of magnitude smaller than the double longitudinal

Lydéric Bocquet

The purpose of the paper is to give a pedagogical introduction to the multiple time-scale technique, on the example of the high friction limit of the Kramers equation. We begin with a discussion of the standard perturbation technique as presented in van Kampen's reference book \refto{VK}, which will be shown to fail in the long-time limit. Application of the

C. Klimcik, P. Severa

A non-Abelian analogue of the Abelian T-duality momentum-winding exchange is described. The non-Abelian T-duality relates $\sigma$-models living on the cosets of a Drinfeld double with respect to its isotropic subgroups. The role of the Abelian momentum-winding lattice is in general played by the fundamental group of the Drinfeld double.

T. L. Stewart, M. W. Kermode, D. J. Beachey, N. Rowley

$\alpha-$decay through a deformed potential barrier produces significant mixing of angular momenta when mapped from the nuclear interior to the outside. Using experimental branching ratios and either semi-classical or coupled-channels transmission matrices, we have found that there is a set of internal amplitudes which are essentially constant for all even--

Daniel Cangemi

A scalar cubic action that classically reproduces the self-dual Yang--Mills equations is shown to generate one-loop QCD amplitudes for external gluon all with the same helicity. This result is related to the symmetries of the self-dual Yang--Mills equations.