May 1996 arXiv papers — page 5

O. Brodbeck, M. Heusler, G. Lavrelashvili N. Straumann, M. S. Volkov

We analyze the stability properties of the purely magnetic, static solutions to the Einstein--Yang--Mills equations with cosmological constant. It is shown that all three classes of solutions found in a recent study are unstable under spherical perturbations. Specifically, we argue that the configurations have $n$ unstable modes in each parity sector, where

Edward P. Osipov

We announce results about the nonperturbative mathematically rigorous construction of the $:\!ϕ^4_4\!:$ quantum field theory in four-dimensional space-time. The complex structure of solutions of the classical nonlinear (real-valued) wave equation and quantization are closely connected among themselves and allow to construct non-perturbatively the quantum fie

V. A. Smirnov

A new version of differential renormalization is presented. It is based on pulling out certain differential operators and introducing a logarithmic dependence into diagrams. It can be defined either in coordinate or momentum space, the latter being more flexible for treating tadpoles and diagrams where insertion of counterterms generates tadpoles. Within thi

V. A. Smirnov

It is shown how strictly four-dimensional integration by parts combined with differential renormalization and its infrared analogue can be applied for calculation of Feynman diagrams.

A. Lorek, A. Ruffing, J. Wess

The q-deformed harmonic oscillator is studied in the light of q-deformed phase space variables. This allows a formulation of the corresponding Hamiltonian in terms of the ordinary canonical variables $x$ and $p$. The spectrum shows unexpected features such as degeneracy and an additional part that cannot be reached from the ground state by creation operators

M. Eliashvili

Chern-Simons-Matter Lagrangian with noncompact gauge symmetry group is considered. The theory is quantized in the holomorphic gauge with a complex gauge fixing condition. The model is discussed, in which the the gauge and matter fields are accompanied by the complex conjugate counterparts. It is argued, that such a theory represents an adequate framework for

K. -H. Rehren

Examples for bounded Bose fields in two dimensions are presented.

H. Banerjee, Asit K. De

A model for lattice fermion is proposed which is, (i) free from doublers, (ii) hermitian, and (iii) chirally invariant. The price paid is the loss of hypercubic and reflection symmetries in the lattice action. Thanks to the $ε$-prescription, correlation functions are free from the ill effects due to the loss of these symmetries. In weak coupling approximatio

Dmitri V. Fursaev, Gennaro Miele

The heat kernels of Laplacians for spin 1/2, 1, 3/2 and 2 fields, and the asymptotic expansion of their traces are studied on manifolds with conical singularities. The exact mode-by-mode analysis is carried out for 2-dimensional domains and then extended to arbitrary dimensions. The corrections to the first Schwinger-DeWitt coefficients in the trace expansio

T. Arens, M. Diehl, O. Nachtmann, P. V. Landshoff

We discuss the reaction $e p \to e \tilde{p} X$ in the one-photon exchange approximation, where it is in essence the reaction $γ^{*} p \to \tilde{p} X$. A large rapidity gap is required between the particle or particles of the proton remnant $\tilde{p}$ and those of $X$. We define a suitable azimuthal angle $φ$ between a leptonic and a hadronic plane. The de

M. Beneke, V. M. Braun

Resummation of large infrared logarithms in perturbation theory can, in certain circumstances, enhance the sensitivity to small gluon momenta and introduce spurious nonperturbative contributions. In particular, different procedures -- equivalent in perturbation theory -- to organize this resummation can differ by $1/Q$ power corrections. The question arises

S. Bellucci

We begin herewith the editing of physics notes taken in the course of Journal Club seminars at INFN-LNF in 1996. The activity consists of informal talks about work in progress and/or review of (more or less) recent physics results of interest to our laboratory. In the section titles the name of the speakers appear, together with the topics discussed in the s

P. A. Henning, R. Fauser

For thermal equilibrium systems it is shown, how the Kubo-Martin-Schwinger boundary condition may be used to factorize the generating functional of Green functions at least on the level of the full two-point function. Genuine non-equilibrium system exhibit correlations that one may also incorporate in the path integral. One one hand this provides a natural t

Tomohiro Matsuda

We examine the supersymmetric non-linear O(N) sigma model with a soft breaking term. In two dimensions, we found that the mass difference between supersymmetric partner fields vanishes accidentally. In three dimensions, the mass difference is observed but O(N) symmetry is always broken also in the strong coupling region.

C. T. Sachrajda

I present a brief introduction to the lattice formulation of quantum field theory, and discuss the use of lattice simulations for studies in particle physics phenomenology. The computation of $f_B$, the decay constant of the $B$-meson, is used as a case study. I also explain the appearance and cancellation of ``renormalons'' in the evaluation of powe

A. Galli

We present a new Monte Carlo algorithm for simulating quantum spin systems which is able to suppress the negative sign problem. This algorithm has only a linear complexity in the lattice size used for the simulation. A general description and a rigorous proof of its correctness is given. Its efficiency is tested on a simple 2-dimensional fermionic model. For

Mauricio Cataldo, Patricio Salgado

We obtain the Einstein-Maxwell equations for (2+1)-dimensional static space-time, which are invariant under the transformation $q_0=i\,q_2,q_2=i\,q_0,α\rightleftharpoons γ$. It is shown that the magnetic solution obtained with the help of the procedure used in Ref.~\cite{Cataldo}, can be obtained from the static BTZ solution using an appropriate transformati

D. Nicholson

We report an upper bound on the strain amplitude of gravitational wave bursts in a waveband from around 800Hz to 1.25kHz. In an effective coincident observing period of 62 hours, the prototype laser interferometric gravitational wave detectors of the University of Glasgow and Max Planck Institute for Quantum Optics, have set a limit of 4.9E-16, averaging ove

Steven R. White, D. J. Scalapino

Using numerical results from density matrix renormalization group (DMRG) calculations for the t-J model, on systems as large as 10x7, we examine the structure of the one and two hole ground states in ladder systems and in two dimensional clusters. A simple theoretical framework is used to explain why holes bind in pairs in two-dimensional antiferromagnets. F

Badrinarayan Krishnamachari, James McLean, Barbara Cooper, James Sethna

In this paper we report simulation studies of equilibrium features, namely circular islands on model surfaces, using Monte-Carlo methods. In particular, we are interested in studying the relationship between the density of vapour around a curved island and its curvature-the Gibbs-Thomson formula. Numerical simulations of a lattice gas model, performed for va

Hiroaki Ikeda, Kazumasa Miyake

It is demonstrated that a {\veck}-dependence of the hybridization matrix element between $f$- and conduction electrons can give rise to an anisotropic hybridization gap of heavy fermions if the filling of electrons corresponds to that of the band insulator. The most interesting case occurs when the hybridization vanishes along some symmetry axis of the cryst

R. Druzinic, W. Hubner

The magnetocrystalline anisotropy energy $E_{anis}$ for free-standing chains (quantum wires) and rings (quantum corrals) of Fe-adatoms $N=$(2...48) is determined using an electronic tight-binding theory. Treating spin-orbit coupling non-perturbatively, we analyze the relationship between the electronic structure of the Fe $d$-electrons and $E_{anis}(n_{d})$,

N. Nayak, S. S. Hassan, T. Biswas

We consider a single Rydberg atom having two degenerate levels interacting with the radiation field in a single-mode ideal cavity. The transition between the levels is carried out by a $Λ$-type degenerate two-photon process via a third level far away from single-photon resonance. At the start of interaction, the atom is considered to be in a coherent superpo

Karl-Peter Marzlin, Jürgen Audretsch

We investigate an atomic three-level $Λ$-system which is exposed to two counterpropagating laser fields (inducing Raman transitions) and which is closed by a magnetic hyperfine field tuned to be in resonance with the transition between the two ground states. The influence of a homogeneous gravitational field is included in a full quantum treatment of the int

R. Haeckl, H. Pilkuhn

The relativistic Breit Hamiltonian between electrons is transformed into an effective vector potential ${\bf A}_i$ for the $i.$th electron, ${\bf A}_i$ having the structure of a recoil--corrected hyperfine operator. Apart from a small three--body operator, the Dirac--Breit equation is now easier applied to relativistic magnetic properties of complex systems.

J. Gomez-Gomar, J. Isern

In this paper we study the application of a simplified method to solve the dynamic radiative transfer problem in expanding envelopes. The method, which requires a computational effort similar to that of the diffusion approximation, is based on the use of a generalization of the Eddington closure relationship allowing the inclusion of scattering and relativis

Yun Wang, Albert Stebbins, Edwin L. Turner

We discuss the gravitational lensing of gravitational waves from merging neutron star binaries, in the context of advanced LIGO type gravitational wave detectors. We consider properties of the expected observational data with cut on the signal-to-noise ratio $ρ$, i.e., $ρ>ρ_0$. An advanced LIGO should see unlensed inspiral events with a redshift distribution

Jordi Miralda-Escude

Microlensing events are now regularly being detected by monitoring the flux of a large number of potential sources and measuring the combined magnification of the images. This phenomenon could also be detected directly from the gravitational deflection, by means of high precision astrometry using interferometry. Relative astrometry at the level of $10\muas$

P. J. Armitage, W. H. Zurek, M. B. Davies

We explore the role that red giants might play in the central regions of Active Galactic Nuclei. Due to their large radii and the low binding energy of the stellar envelope, giants are vulnerable to envelope stripping from collisions with the accretion disk. Using hydrodynamic simulations we show that such collisions will typically deposit a substantial frac

B. Leibundgut

The light curve of a distant Type Ia supernova acts like a clock that can be used to test the expansion of the Universe. SN~1995K, at a spectroscopic redshift of $z = 0.479$, provides one of the first meaningful data sets for this test. We find that all aspects of SN~1995K resemble local supernova Ia events when the light curve is dilated by $(1+z)$, as pres

Yu. I. Manin

An algebro-geometric setting for the study of the Painlevé VI equation is introduced. Hamiltonian form of the equation is realized on a twisted relative cotangent bundle to the universal elliptic curve with labelled points of order two. Relations with the theory of elliptic functions and the quantum cohomology of projective plane are discussed.

Michael Flohr

We find the fusion rules for the c_{p,1} series of logarithmic conformal field theories. This completes our attempts to generalize the concept of rationality for conformal field theories to the logarithmic case. A novelty is the appearance of negative fusion coefficients which can be understood in terms of exceptional quantum group representations. The effec

V. Spiridonov, A. Zhedanov

We study some properties of the Askey-Wilson polynomials (AWP) when q is a primitive N-th root of unity. For general four-parameter AWP, zeros of the N-th polynomial and the orthogonality measure are found explicitly. Special subclasses of the AWP, e.g., the continuous q-Jacobi and big q-Jacobi polynomials, are considered in detail. A set of discrete weight

Valeriy V. Ginzburg, Leo Radzihovsky, Noel A. Clark

We introduce coarse-grained hydrodynamic equations of motion for diffusion-annihilation system with a power-law long-range interaction. By taking into account fluctuations of the conserved order parameter - charge density - we derive an analytically solvable approximation for the nonconserved order parameter - total particle density. Asymptotic solutions are

Kirill V. Krasnov

Quantum theory of geometry, developed recently in the framework of non-perturbative quantum gravity, is used in an attempt to explain thermodynamics of Schwarzschild black holes on the basis of a microscopical (quantum) description of the system. We work with the formulation of thermodynamics in which the black hole is enclosed by a spherical surface B and a

M. T. Grisaru, M. Rocek, R. von Unge

We compute the $1$-loop effective K\"ahler potential in the most general renormalizable $N=1$ $d=4$ supersymmetric quantum field theory.

P. Lacock, C. Michael, P. Boyle, P. Rowland

We discuss in general the construction of gauge-invariant non-local meson operators on the lattice. We use such operators to study the $P$- and $D$-wave mesons as well as hybrid mesons in quenched QCD, with quark masses near the strange quark mass. The resulting spectra are compared with experiment for the orbital excitations. For the states produced by gluo

R. Barbieri, A. Romanino, A. Strumia

In a supersymmetric unified theory or in a generic model where a large neutron electric dipole moment $d_N$ is expected, close to the present bound, we estimate the relation g_aNN = 10^{-21\pm1}(d_N/10^{-25} e cm)(10^10 GeV/f_a) between d_N itself, the scalar coupling g_{aNN} to nucleons of the axion, assumed to exist, and the breaking scale, f_a, of the Pec

F. Guerra, M. Talevi

We study a random resistors network model on a euclidean geometry $\bt{Z}^d$. We formulate the model in terms of a variational principle and show that, under appropriate boundary conditions, the thermodynamic limit of the dissipation per unit volume is finite almost surely and in the mean. Moreover, we show that for a particular thermodynamic limit the resul

M. Chaichian, W. F. Chen, Z. Y. Zhu

The physical state condition in the BRST quantization of Chern-Simons field theory is used to derive Gauss law constraints in the presence of Wilson loops, which play an important role in explicitly establishing the connection of Chern-Simons field theory with 2-dimensional conformal field theory.

P. B. Ramos, M. J. Martins

We formulate in terms of the quantum inverse scattering method the algebraic Bethe ansatz solution of the one-dimensional Hubbard model. The method developed is based on a new set of commutation relations which encodes a hidden symmetry of 6-vertex type.

Gordon W. Semenoff, Richard J. Szabo

We review a class of matrix models whose degrees of freedom are matrices with anticommuting elements. We discuss the properties of the adjoint fermion one-, two- and gauge invariant D-dimensional matrix models at large-N and compare them with their bosonic counterparts which are the more familiar Hermitian matrix models. We derive and solve the complete sets

V. Spiridonov, A. Zhedanov

Properties of the $q$-ultraspherical polynomials for $q$ being a primitive root of unity are derived using a formalism of the $so_q(3)$ algebra. The orthogonality condition for these polynomials provides a new class of trigonometric identities representing discrete finite-dimensional analogs of $q$-beta integrals of Ramanujan.

Chongying Dong, Haisheng Li, Geoffrey Mason

It is proved that Zhu's algebra for vertex operator algebra associated to a positive-definite even lattice of rank one is a finite-dimensional semiprimitive quotient algebra of certain associative algebra introduced by Smith. Zhu's algebra for vertex operator algebra associated to any positive-definite even lattice is also calculated and is related t

S. Scherer, A. Yu. Korchin, J. H. Koch

We investigate the low-energy behavior of the four-point Green's function $Γ^{μν}$ describing virtual Compton scattering off the nucleon. Using Lorentz invariance, gauge invariance, and crossing symmetry, we derive the leading terms of an expansion of the operator in the four-momenta $q$ and $q'$ of the initial and final photon, respectively. The mod

Akihiko Yukie

In this paper, we give an introduction to the rationality of the equivariant Morse stratification, and state the author's results on zeta functions of prehomogeneous vector spaces.

Michael Flohr

We propose a new way for describing the transition between two quantum Hall effect states with different filling factors within the framework of rational conformal field theory. Using a particular class of non-unitary theories, we explicitly recover Jain's picture of attaching flux quanta by the fusion rules of primary fields. Filling higher Landau level

Oskar Pelc, L. P. Horwitz

The space of physical states in relativistic scattering theory is constructed, using a rigorous version of the Dirac formalism, where the Hilbert space structure is extended to a Gel'fand triple. This extension enables the construction of ``a complete set of states'', the basic concept of the original Dirac formalism, also in the cases of unbound

Oskar Pelc, L. P. Horwitz

The Coleman-Mandula theorem, which states that space-time and internal symmetries cannot be combined in any but a trivial way, is generalized to an arbitrarily higher spacelike dimension. Prospects for further generalizations of the theorem (space-like representations, larger time-like dimension, infinite number of particle types) are also discussed. The ori

M. B. Green, N. D. Lambert, G. Papadopoulos, P. K. Townsend

The `electromagnetic' $Sl(2;\bZ)$ duality group in spacetime dimension $D=4k$ can be given a Kaluza-Klein interpretation in $D=4k+2$ as the modular group of a compactifying torus. We show how dyonic $2(k-1)$-branes in $D=4k$ can be interpreted as self-dual $(2k-1)$-branes in $D=4k+2$ wound around the homology cycles of the torus. In particular, dyons of

Kristin Forger, Burt A. Ovrut, Stefan J. Theisen, Daniel Waldram

We explicitly extract the structure of higher-derivative curvature-squared terms at genus 0 and 1 in the d=4 heterotic string effective action compactified on symmetric orbifolds by computing on-shell S-matrix superstring amplitudes. In particular, this is done within the context of calculating the graviton 4-point amplitude. We also discuss the moduli-depen

D. Korotkin, H. Nicolai

We present a detailed account of the isomonodromic quantization of dimensionally reduced Einstein gravity with two commuting Killing vectors. This theory constitutes an integrable ``midi-superspace" version of quantum gravity with infinitely many interacting physical degrees of freedom. The canonical treatment is based on the complete separation of varia

V. A. Tsokur, Yu. M. Zinoviev

In this paper we continue our investigation of the N = 2 supergravity models, where scalar fields of hypermultiplets parameterize the nonsymmetric quaternionic manifolds. Using the results of our previous paper, where we have given an explicit construction for the Lagrangians and the supertransformations and, in-particular, the known global symmetries of the

Su-Long Nyeo

A short outline is given on the application of differential regularization to QCD in the background-field method. The derivation of the propagators in the background gluon field as short-distance expansions is described and the renormalization of the theory is mentioned.

Takanori Fujiwara, Hiroshi Igarashi, Tadao Suzuki

The relation between super-Virasoro anomaly and super-Weyl anomaly in $N=1$ NSR superstring coupled with 2D supergravity is investigated from canonical theoretical view point. The WZW action canceling the super-Virasoro anomaly is explicitly constructed. It is super-Weyl invariant but nonlocal functional of 2D supergravity. The nonlocality can be remedied by

D. K. Park, H. W. Lee, Y. S. Myung, Jin Young Kim

Costa and Matsas (gr-qc/9412030) claimed in their recent paper that a thermal bath does not affect substantially the transition probability for fast moving inertial Unruh detector. It is shown that their claim holds only for small $βΔE$. We show that, for large enough $βΔE$, the transition probability is not monotonically decreasing function of the detector&

Thomas G. Rizzo

The rate and corresponding gluon jet energy distribution for the process $e^+e^- \to t\bar tg$ are sensitive to the presence of anomalous dipole-like couplings of the top to the photon and $Z$ at the production vertex. For sizeable anomalous couplings of this type substantial deviations from the expectations of the Standard Model are likely. We explore the c

B. Masuda, L. H. Orr, W. J. Stirling

In reconstructing the top quark momentum from its decay products, one must account for extra jets that can result from radiation of gluons. In this paper we study soft gluon radiation in top production and decay at the Fermilab Tevatron. We consider the cases where one or both $W$ bosons decays hadronically, {\it i.e.}, where at least one of the top quarks c

A. L. Kataev, A. V. Kotikov, G. Parente, A. V. Sidorov

The next-to-next-to-leading order (NNLO) non-singlet QCD analysis of the experimental data of the CCFR collaboration for the $xF_3$ and $F_2$ structure functions of the deep-inelastic scattering of neutrinos and antineutrinos on the nucleon by means of the Jacobi polinomial expansion method is made. The target mass corrections are also taken into account. We

Wu-Sheng Dai, Song Gao, Xue-Qian Li

We study the $ν_μ$ and $ν_τ$ decays in the early epoch of the universe. If $m_{ν_τ}>2m_e$, there would be a CP asymmetry between $ν_τ\rightarrow e^++e^-+ν_e$ and $\barν_τ \rightarrow e^++e^-+\barν_e$. The resultant CP non-invariance is a function of temperature and density and can reach $10^{-7}$ for a reasonable temperature range, but it is noticed that if

I. Caprini, C. Macesanu

A method of deriving bounds on the weak meson form factors, based on perturbative QCD, analyticity and unitarity, is generalized in order to fully exploit heavy quark spin symmetry in the ground state $(L=0)$ doublet of pseudoscalar $(B)$ and vector $(B^*)$ mesons. All the relevant form factors of these mesons are taken into account in the unitarity sum. The

Tomohiro Matsuda

We examine the phase structures of the supersymmetric O(N) sigma model in two and three dimensions by using the tadpole method. Using this simple method, the calculation is largely simplified and the characteristics of this theory become clear. We also examine the problem of the fictitious negative energy state.

Martina Brisudova, Robert Perry

We study the part of the renormalized, cutoff QED light-front Hamiltonian that does not change particle number. The Hamiltonian contains interactions that must be treated in second-order bound state perturbation theory to obtain hyperfine structure. We show that a simple unitary transformation leads directly to the familiar Breit-Fermi spin-spin and tensor i

Christian Holm, Wolfhard Janke

In a recent letter, R.G. Brown and M. Ciftan (Phys. Rev. Lett. 76, 1352, 1996) reported high precision Monte Carlo (MC) estimates of the static critical exponents of the classical 3D Heisenberg model, which stand in sharp contrast to values obtained by four independent approaches, namely by other recent high statistics MC simulations, high-temperature series

Matts Roos, Leonid A. Khalfin

We discuss the appearance of negative numbers of events in radiochemical experiments and negative squared antineutrino mass $m^2_{\barν_e}$ in tritium beta decay. Going beyond the standard discussion about how to extract upper limits in those cases, we show that the problem is much more profound. We explain the circumstances which are the likely cause of the

S. Tapprogge

New results on diffractive deep-inelastic $e p$ scattering at HERA are presented using data taken in 1994 with the H1 detector. The cross section for diffractive deep-inelastic scattering is measured in terms of a diffractive structure function $F_2^{D(3)}(β,Q^2,\xpom)$ over an extended kinematic range. The dependence of $F_2^{D(3)}$ on $\xpom$ is found not

P. Fiziev, H. Kleinert

We exhibit the transformation properties of the mechanical action principle under anholonomic transformations. Using the fact that spaces with torsion can be produced by anholonomic transformations we derive the correct action principle in these spaces which is quite different from the conventional action principle.

Bhargavi Srinivasan, S. Ramasesha, H. R. Krishnamurthy

We develop a new $\it {symmetrized}$ version of the Projector Quantum Monte Carlo (SPQMC) method which preserves the symmetries of the system by simultaneously sampling all symmetry related Ising configurations at each MC step and use it to study the effect of electron correlations on a single $C_{60}$ molecule and its structural motifs, within the Hubbard m

Hiroaki Kusunose, Kazumasa Miyake

It is shown on the basis of the multiplicative renormalization-group method of two-loop order that the low-energy effective Hamiltonian of a strongly coupled local electron-phonon system is mapped to the two-channel Kondo model. A phonon is treated as an Einstein oscillator with restricted Hilbert space such that up to one-phonon process is taken into accoun

D. S. Golubev, A. D. Zaikin

Electron tunneling through mesoscopic metallic grains can be treated perturbatively only provided the tunnel junction conductances are sufficiently small. If it is not the case, fluctuations of the grain charge become strong. As a result (i) contributions of all -- including high energy -- charge states become important and (ii) excited charge states become

M. Onoda, I. Ichinose, T. Matsui

We study the finite temperature properties of the gauge theory of nonrelativistic fermions by using RPA and ladder approximation. This gauge theory is relevant to two interesting systems: high-Tc superconductivity and electrons in the half-filled Landau level.

Masanori Yamanaka, Naoto Nagaosa

The conductance through a magnetic domain wall is calculated for the double exchange system as a function of energy and the width of the domain wall. It is shown that when the carrier density is low enough, the blockade is almost complete even for the smoothly varying spin configuration, i.e., large width of the domain wall. This result is applied to the man

M. Villar-Martin

There are strong evidences which favour the existence of dust in active galaxies. Understanding the way in which dust interacts with the radiation and influences the physical conditions of the gas is crucial if we want to learn about the nature of the central active nucleus and about the physical conditions of the ISM in such galaxies. Not taking into accoun

R. C. Kraan-Korteweg, A. P. Fairall, P. A. Woudt, G. C. Van de Steene

Spectroscopic observations have been carried out for eleven objects believed to be planetary nebulae on the basis of their optical appearance. They were discovered in an ongoing deep search for galaxies in the Southern Milky Way (Kraan-Korteweg & Woudt 1994). The objects were observed with the 1.9m telescope of the South African Astronomical Observatory duri

D. L. Clements, W. J. Couch

We present the results of colour-selection of candidate high redshift (2.6 $<$ z $<$ 3.9) galaxies within the Hubble Deep Field based on the Ly-break at 912Å. We find 8 such objects in the region, giving a comoving number density comparable to that of nearby bright galaxies (for a flat q$_0$=0.5, H$_0$=100 kms$^{-1}$Mpc$^{-1}$ universe). We provide basic dat

Paolo Ciliegi, Tommaso Maccacaro

Using a sample of 63 AGNs extracted from the $Einstein$ Extended Medium Sensitivity Survey (EMSS), we study the X-ray spectral properties of X-ray selected AGN in the 0.1$-$2.4 keV ROSAT band. These objects are all the EMSS AGN detected with more than 300 net counts in ROSAT PSPC images available from the public archive (as of May 31, 1995). A Maximum-Likeli

Yu. A. Neretin

We propose a construction of separated quotient space and apply this construction for simple description of Study-Semple-Satake-Furstenberg-De Concini-Procesi-Oshima boundary of symmetric space

Tom Banks, Michael Dine

If nature is described by string theory, and if the compactification radius is large (as suggested by the unification of couplings), then the theory is in a regime best described by the low energy limit of $M$-theory. We discuss some phenomenological aspects of this view. The scale at which conventional quantum field theory breaks down is of order the unific

Randall D. Kamien, T. C. Lubensky

The molecules in lyotropic membranes are typically aligned with the surface normal. When these molecules are chiral, there is a tendency for the molecular direction to twist. These competing effects can reach a compromise by producing helicoidal defects in the membranes. Unlike thermotropic smectics, the centers of these defects are hollow and thus their ene

G. T. Bodwin, D. K. Sinclair, S. Kim

We calculate the long-distance matrix elements for the decays of the lowest-lying S- and P-wave states of charmonium and bottomonium in quenched lattice QCD, using a nonrelativistic formulation for the heavy quarks. (The short-distance coefficients are known from perturbation theory.) In particular, we present the first calculation from QCD first principles

Christopher W. Mauche

EUVE, ROSAT, and ASCA observations of the boundary layer emission of nonmagnetic cataclysmic variables (CVs) are reviewed. EUVE spectra reveal that the effective temperature of the soft component of high-Mdot nonmagnetic CVs is kT ~ 10-20 eV and that its luminosity is ~ 0.1-0.5 times the accretion disk luminosity. Although the EUV spectra are very complex an

M. M. Romanova, R. V. E. Lovelace

A model is developed for the time dependent electromagnetic - radio to gamma-ray - emission of active galactic nuclei, specifically, the blazars, based on the acceleration and creation of leptons at a propagating discontinuity or {\it front} of a Poynting flux jet. The front corresponds to a discrete relativistic jet component as observed with very-long-base

J. Lopez, D. Nanopoulos

We show that leptophobic $Z&#39;$ gauge bosons occur naturally in flipped SU(5) and may shift $R_b$ in an interesting way without upsetting the good values of $Γ_{had}$ and $R_c$. Within a string-derived version of the model, we study three possible scenarios and the constraints imposed on model building that would allow the new symmetry to remain unbroken d

A Crisanti, M. Falcioni, G. Lacorata, R. Purini

We discuss how to characterize the behavior of a chaotic dynamical system depending on a parameter that varies periodically in time. In particular, we study the predictability time, the correlations and the mean responses, by defining a local--in--time version of these quantities. In systems where the time scale related to the time periodic variation of the

Tigran Aivazian

Einstein-Vlasov system is solved for a homogeneous isotropic spacetime with positive curvature. In the case of the Universe consisting of massless particles the equation for R(t) is solved analytically.

Lian Zheng, R. J. Radtke, S. Das Sarma

We study intersubband spin density collective modes in double-layer quantum Hall systems at $ν=2$ within the time-dependent Hartree-Fock approximation. We find that these intersubband spin density excitations may soften under experimentally accessible conditions, signaling a phase transition to a new quantum Hall state with interlayer inplane antiferromagnet

Manfred Lindner, Manfred Weiser

We explore possibilities of gauge coupling unification in left--right symmetric models with non--minimal particle content. In addition to unification we require the absence of anomalies and sufficient proton lifetime. Numerous previously unknown solutions are presented where unification occurs within the latest experimental errors. Solutions exist where the

T. J. Newman, A. J. McKane

We present a continuum formulation of a (d+1)-dimensional directed line interacting with sparse potentials (i.e. d-dimensional potentials defined only at discrete longitudinal locations.) An iterative solution for the partition function is derived. The impulsive influence of the potentials induces discontinuities in the evolution of the probability density P

Han-Wen Huang, Kuang-Ta Chao

In the framework of a newly developed factorization formalism which is based on NRQCD, explicit cancellations are shown for the infrared divergences that appeared in the previously calculated hadronic annihilation decay rates of P-wave and D-wave heavy quarkonia. We extend them to a more general case that to leading order in $v^2$ and next-to-leading order i

Li Hua Yu

Applying a technique developed in a recent work[1] to calculate wavefunction evolution in a dissipative system with Ohmic friction, we show that the wavelength of the wavefunction decays exponentially, while the Brownian motion width gradually increases. In an interference experiment, when these two parameters become equal, the Brownian motion erases the fri

C. K. Au, Chi-Keung Chow, Chong-Sun Chu

A simple closed form expression is obtained for the scattering phase shift perturbatively to any given order in effective one-dimensional problems. The result is a hierarchical scheme, expressible in quadratures, requiring only knowledge of the zeroth order solution and the perturbation potential.

Angel Ballesteros, Francisco J. Herranz

The non-standard (Jordanian) quantum deformations of $so(2,2)$ and (2+1) Poincaré algebras are constructed by starting from a quantum $sl(2,\R)$ basis such that simple factorized expressions for their corresponding universal $R$-matrices are obtained. As an application, the null-plane quantum (2+1) Poincaré Poisson-Lie group is quantized by following the FRT

B. Enriquez, B. Feigin, V. Rubtsov

We construct an elliptic analogue of Sklyanin&#39;s separation of variables for the $sl(2)$ Gaudin system, using an adaptation of Drinfeld&#39;s Radon transformations.

Yoshitaka Koyama

We construct a representation of $U_q(\widehat{sl}_2)$ at level $-1/2$ by using the bosonic Fock spaces. The irreducible modules are obtained as the kernel of a certain operator, in contrast to the construction by Feingold and Frenkel for $q=1$ where such a procedure is not necessary. We also bosonize the $q$-vertex operators associated with the vector repre

P. C. Tandy

We discuss form factors and coupling constants for the $γ^* π^0 γ$, $ρππ$ and $γπρ$ interactions generated by a model field theory that produces finite size $\bar{q}q$ meson modes. The approach implements dressing of the vertices and propagators consistent with dynamical chiral symmetry breaking, gauge invariance, quark confinement and perturbative QCD.

V. D. Efros, H. Oberhummer

We extract energies and widths of the ground states of $^5$He and $^5$Li from recent single--level R--matrix fits to the spectra of the $^3$H$({\rm d},γ$)$^5$He and the $^3$He$({\rm d},γ$)$^5$Li reactions. The widths obtained differ significantly from the formal R--matrix values but they are close to those measured as full widths at half maxima of the spectr

A. E. Litvak, V. D. Milman, A. Pajor

This article gives estimates on covering numbers and diameters of random proportional sections and projections of symmetric quasi-convex bodies in $\mathbb R$. These results were known for the convex case and played an essential role in development of the theory. Because duality relations can not be applied in the quasi-convex setting, new ingredients were i

Georg Keller, Christoph Kopper, Clemens Schophaus

We show within the Wilson renormalization group framework how the flow equation method can be used to prove the perturbative renormalizability of a relativistic massive selfinteracting scalar field. Furthermore we prove the regularity of the renormalized relativistic one-particle irreducible n-point Green functions in the region predicted by axiomatic quantu

Alexander Gorsky

We suggest the quasiparticle picture behind the integrable structure of N=2 SYM theory,which arises if the Lax operator is considered as a Hamiltonian for the fermionic system. We compare the meaning of BPS states with the one coming from the D-brane interpretation and give some evidence for the compositeness of the selfdual strings. The temperature phase tr

V. A. Tsokur, Yu. M. Ziniviev

In this paper we consider the N = 2 supergravity models in which the hypermultiplets realize the nonlinear sigma-models, corresponding to the nonsymmetric (but homogeneous) quaternionic manifolds. By exploiting the isometries of appropriate manifolds we give an explicit construction for the Lagrangians and supertransformation laws in terms of usual hypermult