September 1996 arXiv papers — page 2

Mark J. Gotay, Hendrik B. Grundling

In this paper we continue our study of Groenewold-Van Hove obstructions to quantization. We show that there exists such an obstruction to quantizing the cylinder $T^*S^1.$ More precisely, we prove that there is no quantization of the Poisson algebra of $T^*S^1$ which is irreducible on a naturally defined $e(2) \times R$ subalgebra. Furthermore, we determine

Mannque Rho

In this talk, I discuss how the changes in the QCD vacuum induced by increasing nuclear matter density affect nuclear properties under normal as well as extreme conditions. The quark condensate which is the order parameter for the mode in which chiral symmetry is manifested is expected to change as matter density or temperature is changed. The topics discuss

Takehisa Fujita, Makoto Hiramoto, Hidenori Takahashi

We discuss the bound states of the massive Thirring model. Here, the periodic boundary condition equations for the Bethe ansatz solutions are numerically solved. It is found that the massive Thirring model has only one bound state and the bound state spectrum as the function of the coupling constant agrees with that of infinite momentum frame prescription by

Kenichiro Aoki, Eric D'Hoker

We summarize recent work, in which we consider scattering amplitudes of non-critical strings in the limit where the energy of all external states is large compared to the string tension. We show that the high energy limit is dominated by a saddle point that can be mapped onto an electrostatic equilibrium configuration of an assembly of charges associated wit

Alexander Belopolsky

We show that the BRST operator of Neveu-Schwarz-Ramond superstring is closely related to de Rham differential on the moduli space of decorated super-Riemann surfaces P. We develop formalism where superstring amplitudes are computed via integration of some differential forms over a section of P over the super moduli space M. We show that the result of integra

Toru Goto, Yasuhiro Okada, Yasuhiro Shimizu, Minoru Tanaka

The $b \rightarrow s l^+ l^-$ process is studied in the minimal supergravity model in detail. Taking account of the long distance contributions from the $c\overline{c}$ resonances, we calculate the branching ratio and the lepton forward-backward asymmetry in this model. We find that there is a strong correlation between the branching ratios of $b \rightarrow

Sourendu Gupta, Prakash Mathews

We investigate the pattern of asymmetries in the colour-octet model for inclusive production of charmonium with polarised initial state hadrons and photons. We find that singly polarised asymmetries vanish. The double polarised asymmetry for J/psi involves a new combination of long-distance matrix element. We also investigate the asymmetries for eta_c, chi_c

A. Ali Khan, T. Bhattacharya

We present preliminary results from our study of the heavy-light spectrum and decay constants. For the heavy quark, we use NRQCD at various masses around and above the $b$ quark mass. For the first time, the heavy quark action and the heavy-light current consistently include corrections at second order in the non-relativistic expansion, as well as the leadin

Wolfhard Janke, Stefan Kappler

We report numerical simulations of two-dimensional $q$-state Potts models with emphasis on a new quantity for the computation of spatial correlation lengths. This quantity is the cluster-diameter distribution function $G_{diam}(x)$, which measures the distribution of the diameter of stochastically defined cluster. Theoretically it is predicted to fall off ex

R. Gupta, T. Bhattacharya

We present estimates of light quarks masses using lattice data. Our main results are based on a global analysis of all the published data for Wilson and Staggered fermions, both in the quenched approximation and with $n_f=2$ dynamical flavors. The Wilson and Staggered results agree after extrapolation to the continuum limit for both the $n_f=0,2$ theories. O

Wolfhard Janke

Using two sets of high-precision Monte Carlo data for the two-dimensional XY model in the Villain formulation on square $L \times L$ lattices, the scaling behavior of the susceptibility $χ$ and correlation length $ξ$ at the Kosterlitz-Thouless phase transition is analyzed with emphasis on multiplicative logarithmic corrections $(ln L)^{-2r}$ in the finite-si

Shoichi Sasaki, Masahiro Fukushima, Atsunori Tanaka, Hideo Suganuma

We study the correlation between instantons and QCD-monopoles both in the lattice gauge theory and in the multi-instanton system using the maximally abelian gauge. First, we find the existence of an almost linear correlation between the total length of monopole trajectories and the total number of pseudoparticles (instantons and anti-instantons) in the $16^{

Rong-Gen Cai, Yuan-Zhong Zhang

The static, plane symmetric solutions and cylindrically symmetric solutions of Einstein-Maxwell equations with a negative cosmological constant are investigated. These black configurations are asymptotically anti-de Sitter not only in the transverse directions, but also in the membrane or string directions. Their causal structure is similar to that of Reissn

H. F. Dowker, R. D. Sorkin

We review the mechanism in quantum gravity whereby topological geons, particles made from non-trivial spatial topology, are endowed with nontrivial spin and statistics. In a theory without topology change there is no obstruction to ``anomalous'' spin-statistics pairings for geons. However, in a sum-over-histories formulation including topology change

A. M. Smondyrev, Robert A. Pelcovits

We present the results of molecular dynamics simulations of the Gay-Berne model of liquid crystals, supercooled from the nematic phase. We find a glass transition to a metastable phase with nematic order and frozen translational and orientational degrees of freedom. For fast quench rates the local structure is nematic-like, while for slower quench rates smec

Frank Milde, Rudolf A. Römer, Michael Schreiber

We study the Anderson model of localization with anisotropic hopping in three dimensions for weakly coupled chains and weakly coupled planes. The eigenstates of the Hamiltonian, as computed by Lanczos diagonalization for systems of sizes up to $48^3$, show multifractal behavior at the metal-insulator transition even for strong anisotropy. The critical disord

Daniel Schaerer, William D. Vacca

We present the first results of a new set of population synthesis models, which utilize the latest stellar evolutionary tracks, recent non-LTE atmosphere models which include stellar winds, and observed line strengths in WR spectra to predict the relative strengths of various WN and WC/WO emission features in the spectra of starburst galaxies. Our results wi

C. Adami, N. J. Cerf

We discuss the capacity of quantum channels for information transmission and storage. Quantum channels have dual uses: they can be used to transmit known quantum states which code for classical information, and they can be used in a purely quantum manner, for transmitting or storing quantum entanglement. We propose here a definition of the von Neumann capaci

Vyjayanthi Chari, Andrew Pressley

We study the restricted form of the qaunatized enveloping algebra of an untwisted affine Lie algebra and prove a triangular decomposition for it. In proving the decomposition we prove several new identities in the quantized algebra, one of these show a connection between the quantized algebra and Young diagrams. These identities are all invisible in the non-

P. K. Townsend

Some aspects of the role of p-branes in non-perturbative superstring theory and M-theory are reviewed. It is then shown how the Chern-Simons terms in D=10 and D=11 supergravity theories determine which branes can end on which, i.e. the `brane boundary rules'.

Shoichi Sasaki, Hideo Suganuma, Hiroshi Toki

We study the chiral phase transition at $T\neq 0$ in the dual Ginzburg-Landau theory using the Schwinger-Dyson (SD) equation. In order to solve the SD equation at $T\neq 0$, we provide a new ansatz for the quark self-energy in the imaginary-time formalism. The recovery of the chiral symmetry is found at $T_{_{C}}\sim 100 MeV$ with realistic parameters, which

Marek Czachor

The EPRB experiment with massive partcles can be formulated if one defines spin in a relativistic way. Two versions are discussed: The one using the spin operator defined via the relativistic center-of-mass operator, and the one using the Pauli-Lubanski vector. Both are shown to lead to the SAME prediction for the EPRB experiment: The degree of violation of

Mark J. Hadley

It is shown that certain structures in classical General Relativity can give rise to non-classical logic, normally associated with Quantum Mechanics. A 4-geon model of an elementary particle is proposed which is asymptotically flat, particle-like and has a non-trivial causal structure. The usual Cauchy data are no longer sufficient to determine a unique evol

Gregory L. Eyink

A fluctuation law of the energy in freely-decaying, homogeneous and isotropic turbulence is derived within standard closure hypotheses for 3D incompressible flow. In particular, a fluctuation-dissipation relation is derived which relates the strength of a stochastic backscatter term in the energy decay equation to the mean of the energy dissipation rate. The

P. Bialas, Z. Burda, D. Johnston

We analyse the properties of a very simple ``balls-in-boxes'' model which can exhibit a phase transition between a fluid and a condensed phase, similar to behaviour encountered in models of random geometries in one, two and four dimensions. This model can be viewed as a generalisation of the backgammon model introduced by Ritort as an example of glas

L. P. Grishchuk

The observed microwave background anisotropies in combination with the theory of quantum mechanically generated cosmological perturbations predict a well measurable amount of relic gravitational waves in the frequency intervals tested by LISA and ground-based laser interferometers.

Masato Hisakado

We discussed the full unitary matrix models from the view points of integrable equations and string equations. Coupling the Toda equations and the string equations, we derive a special case of the Painlevé III equation. From the Virasoro constrains, we can use the radial coordinate. The relation between $t_{1}$ and $t_{-1}$ is like the complex conjugate. %An

J. N. Pecina-Cruz

In this paper, an explicit expression for the Casimir operator (or the Casimir invariant) of the inhomogeneous group ISL(n,R) in its enveloping algebra is proposed, which using contractions of the tenso- rial indices of the generating operators P^{rho} and E^{nu}{mu} may be presented in the following (slightly more comprehensible as equation (1)) form. The C

S. Umisedo, S. Sasaki, H. Suganuma, H. Toki

Using the effective potential formalism, we study dynamical chiral symmetry breaking (D$χ$SB) in the dual Ginzburg-Landau (DGL) theory, where the color confinement is brought by monopole condensation. The effective potential as a function of infrared quark mass is found to have double-well structure, which leads to spontaneous breaking of chiral symmetry. To

L. S. F. Olavo

In this paper we are interested in unraveling the mathematical connections between the stochastic derivation of Schrödinger equation and ours. It will be shown that these connections are given by means of the time-energy dispersion relation and will allow us to interpret this relation on more sounded grounds. We also discuss the underlying epistemology.

C. Ciofi degli Atti, L. P. Kaptari, S. Scopetta

It is shown that in deep inelastic electron - ion collisions the detection, in coincidence with the scattered electron, of a nucleus A-1 in the ground state, as well as a nucleon and a nucleus A-2 also in the ground state, may provide unique information on several long standing problems, such as the origin of the EMC effect, the possible medium modifications

P. C. R. Cardoso de Mello, S. Carneiro, M. C. Nemes

The purpose of this paper is to formulate an action principle which allows for the construction of a classical lagrangean including both electric and magnetic currents. The lagrangean is non-local and shown to yield all the expected (local) equations for dual electrodynamics.

Michael Engelhardt, Shimon Levit

Matrices are said to behave as free non-commuting random variables if the action which governs their dynamics constrains only their eigenvalues, i.e. depends on traces of powers of individual matrices. The authors use recently developed mathematical techniques in combination with a standard variational principle to formulate a new variational approach for ma

M. Passare, A. K. Tsikh, A. A. Cheshel

We give a representation, in terms of iterated Mellin-Barnes integrals, of periods on multi-moduli Calabi-Yau manifolds arising in superstring theory. Using this representation and the theory of multidimensional residues, we present a method for analytic continuation of the fundamental period in the form of Horn series.

Amitabha Lahiri

When an antisymmetric tensor potential is coupled to the field strength of a gauge field via a $B\wedge F$ coupling and a kinetic term for $B$ is included, the gauge field develops an effective mass. The theory can be made invariant under a non-abelian vector gauge symmetry by introducing an auxiliary vector field. The covariant quantization of this theory r

D. Ring

We present a scenario of neutrino masses and mixing angles. Each generation includes a sterile right handed neutrino in addition to the usual left handed one. We assume a hierarchy in their Dirac masses similar to, but much larger than the hierarchies in the quarks and charged leptons. In addition, we include a Majorana mass term for the sterile neutrinos on

Gregory Mahlon

We describe a method for searching for a light stop squark [M(stop)+M(LSP)<M(t)] at the Fermilab Tevatron. Traditional searches rely upon stringent background-reducing cuts which, unfortunately, leave very few signal events given the present data set. To avoid this difficulty, we suggest using a milder set of cuts, combined with a ``superweight,&#39;&#39; wh

Haim Goldberg

This work examines the confining-deconfining phase transition in a hidden Yang Mills sector with scale $Λ\sim 10^{14}$ GeV appropriate to dilaton stabilization and SUSY-breaking via formation of a gaugino consensate. If the transition is assumed to take place through homogenous nucleation, then under reasonable assumptions it is found that a critical bubble,

D. Melikhov, N. Nikitin

Hadronic matrix elements of the vector, axial-vector and tensor currents relevant for exclusive rare decays $B\to(π,ρ,K,K^*)\,l^+l^-$ induced by the quark transition $b\to d,s$ are analysed using dispersion formulation of the light-cone constituent quark model. The form factors in the decay region are expressed as relativistic double spectral representations

J. H. Kuehn, E. Mirkes

CP violating signals in semileptonic $τ$ decays are studied. These can be observed in decays of unpolarized single $τ$&#39;s even if their rest frame cannot be reconstructed. No beam polarization is required. The importance of the two meson channel, in particular the $Kπ$ final state is emphasized.

Laurent Lellouch

I present a recent piece of work on semileptonic $B \to π$ decays in which lattice results and kinematical and dispersive constraints are combined to obtain model-independent bounds on the relevant form factors and rates.

Matteo Cacciari, Michael Krämer

We work out and review prospects for future quarkonium physics at HERA. We focus on the impact of color-octet contributions and discuss how measurements at HERA can be used to test the picture of quarkonium production as developed in the context of the NRQCD factorization approach.

C. F. Baillie, W. Janke, D. A. Johnston

We perform extensive Monte Carlo simulations of the 10-state Potts model on quenched two-dimensional $Φ^3$ gravity graphs to study the effect of quenched connectivity disorder on the phase transition, which is strongly first order on regular lattices. The numerical data provides strong evidence that, due to the quenched randomness, the discontinuous first-or

Stefan Soldner-Rembold

The inclusive one- and two-jet cross-sections are measured in collisions of quasi-real photons at e+e- centre-of-mass energies of 130 and 136 GeV using the OPAL detector at LEP. Jets are reconstructed with a cone jet finding algorithm. The jet cross-sections are compared to next-to-leading order (NLO) perturbative QCD calculations. Transverse energy flows in

James E. Lidsey

A global O$(2,2)$ symmetry is found in the Brans-Dicke theory of gravity when the dilaton is coupled to axion and moduli fields. The symmetry is broken if a cosmological constant is introduced. Within the class of spatially homogeneous Bianchi cosmologies, only the type I and V models respect the symmetry. Isotropic cosmological solutions are found for arbit

F. Marsiglio

The ground state energy and energy gap to the first excited state are calculated for the attractive Hubbard model in one dimension using both the Bethe Ansatz equations and the variational BCS wavefunction. Comparisons are provided as a function of coupling strength and electron density. While the ground state energies are always in very good agreement, the

Vladimir Golovanov, Laszlo Mihaly, A. R. Moodenbaugh

The dc resistivity, magnetoresistance and magnetic susceptibility of La(1-x)SrxCoO3 compounds have been investigated in the temperature range of 4K to 300K for magnetic fields up to 7 T. In the doping range studied (0.05 - x - 0.25) the electronic properties of the material exhibit a crossover from semiconducting to metallic behavior. The magnetoresistance i

K. A. Matsuoka, K. K. Likharev, P. Dresselhaus, L. Ji

We have carried out a coordinated experimental and theoretical study of single-electron traps based on submicron aluminum islands and aluminum oxide tunnel junctions. The results of geometrical modeling using a modified version of MIT&#39;s FastCap were used as input data for the general-purpose single-electron circuit simulator MOSES. The analysis indicates

Alain Pumir, Boris I. Shraiman, Eric D. Siggia

The third order correlation function of the scalar field advected by a Gaussian random velocity, with a spatial scaling exponent $2 - ε$, and in the presence of a mean gradient, is calculated perturbatively in $ε<< 1$. This expansion corresponds to the regime close to Batchelor&#39;s advection by linear diffeomorphisms. The scaling exponent is found to be eq

Silvio Franz, Felix Ritort

We examine the density-density correlation function in a model recently proposed to study the effect of entropy barriers in glassy dynamics. We find that the relaxation proceeds in two steps with a fast beta process followed by alpha relaxation. The results are physically interpreted in the context of an adiabatic approximation which allows to separate the t

M. Fricke, A. Lorke, J. P. Kotthaus, G. Medeiros-Ribeiro

Using far-infrared spectroscopy, we investigate the excitations of self-organized InAs quantum dots as a function of the electron number per dot, 1<n<6, which is monitored in situ by capacitance spectroscopy. Whereas the well-known two-mode spectrum is observed when the lowest s - states are filled, we find a rich excitation spectrum for n=3, which reflects

M. Benakli, H. Zheng, M. Gabay

We present a new variational approach to the study of phase transitions in frustrated 2D XY models. In the spirit of Villain&#39;s approach for the ferromagnetic case we divide thermal excitations into a low temperature long wavelength part (LW) and a high temperature short wavelength part (SW). In the present work we mainly deal with LW excitations and we e

M. Fricke, A. Lorke, M. Haslinger, J. P. Kotthaus

The many-particle ground state and excitations of self-assembled InAs quantum dots are investigated using far-infrared (FIR) and capacitance spectroscopy. The contributions of quantization and charging energies to the $n$--electron energy spectrum are determined. For $n = 1$, 2, we find good agreement with a parabolic model; for higher filling, the Coulomb i

Daniel Koller, Michael C. Martin, Laszlo Mihaly, Gyorgy Mihaly

Tunneling and optical transmission studies have been performed on superconducting samples of Rb3C60. At temperatures much below the superconducting transition temperature Tc the energy gap is 2 Delta=5.2 +- 0.2meV, corresponding to 2 Delta/kB Tc = 4.2. The low temperature density of states, and the temperature dependence of the optical conductivity resembles

A. Lorke, M. Fricke, B. T. Miller, M. Haslinger

We review a number of recent experiments which are probing ground state and excitations of few-electron systems in self-assembled InAs quantum dots. Far-infrared spectroscopy, together with local as well as large-scale capacitive probing allows for a detailed investigation of the different contributions to the many-particle spectrum in the dots. The influenc

Y. Avishai, J. M. Luck

We investigate dynamical scaling properties in the integer quantum Hall effect for non-interacting electrons at zero temperature, by means of the frequency-induced peak broadening of the dissipative longitudinal conductivity $σ_{xx}(ω)$. This quantity is calculated numerically in the lowest Landau level for various values of the Fermi energy $E$, of the freq

F. Igloi, H. Rieger

We consider random transverse-field Ising spin chains and study the magnetization and the energy-density profiles by numerically exact calculations in rather large finite systems ($L\le 128$). Using different boundary conditions (free, fixed and mixed) the numerical data collapse to scaling functions, which are very accurately described by simple analytic ex

Gerald Bedürftig, Fabian H. L. Eßler, Holger Frahm

An impurity coupling to both spin and charge degrees of freedom is added to a periodic t-J chain such that its interaction with the bulk can be varied continuously without losing integrability. Ground state properties, impurity contributions to the susceptibilities and low temperature specific heat are studied as well as transport properties. The impurity ph

B. Groh, S. Dietrich

We investigate fluids of dipolar hard particles by a certain variant of density-functional theory. The proper treatment of the long range of the dipolar interactions yields a contribution to the free energy which favors ferromagnetic order. This corrects previous theoretical analyses. We determine phase diagrams for dipolar ellipsoids and spherocylinders as

Sergio Conti, Gaetano Senatore

We prove that the predicted charge transfer state in symmetric bilayers of two dimensional electron gases is always unstable at zero bias voltage, due to interlayer correlation and/or tunneling. This is most easily seen by resorting to a pseudospin formalism and considering coherent states obtained from the charge transfer state through rotations of the pseu

Don D. Frantz

Heat capacity curves as functions of temperature were calculated using Monte Carlo methods for the series of Ar_{13-n}Kr_n clusters (0 <= n <= 13). The clusters were modeled classically using pairwise additive Lennard-Jones potentials. J-walking (or jump-walking) was used to overcome convergence difficulties due to quasiergodicity present in the solid-liquid

N. Boccara, H. Fuks, S. Geurten

A new class of automata networks is defined. Their evolution rules are determined by a probability measure p on the set of all integers Z and an indicator function I_A on the interval [0,1]. It is shown that any cellular automaton rule can be represented by a (nonunique) rule formulated in terms of a pair (p,I_A). This new class of automata networks contains

Konrad Banaszek, Krzysztof Wodkiewicz

We discuss a balanced homodyne detection scheme with imperfect detectors in the framework of the operational approach to quantum measurement. We show that a realistic homodyne measurement is described by a family of operational observables that depends on the experimental setup, rather than a single field quadrature operator. We find an explicit form of this

K. Iwasawa, A. C. Fabian, S. Ueno, H. Awaki

We present results on the Seyfert 2 galaxy NGC4388 in the Virgo cluster observed with ASCA during its PV phase. The 0.5-10 keV X-ray spectrum consists of multiple components; (1) a continuum component heavily absorbed by a column density NH = 4E23 cm-2 above 3 keV; (2) a strong 6.4 keV line (EW = 500 eV); (3) a weak flat continuum between 1 and 3 keV; and (4

T. A. Ensslin, P. L. Biermann, P. P. Kronberg, X. -P. Wu

The masses of clusters of galaxies estimated by gravitational lensing exceed in many cases the mass estimates based on hydrostatic equilibrium. This may suggest the existence of nonthermal pressure. We ask if radio galaxies can heat and support the cluster gas with injected cosmic ray protons and magnetic field densities, which are permitted by Faraday rotat

B. M. Deiss, W. Reich, H. Lesch, R. Wielebinski

We present new measurements of the diffuse radio emission from the Coma cluster of galaxies at 1.4 GHz using the Effelsberg 100-m-telescope. The halo source Coma C has an extent down to noise of about 80 arcmin corresponding to 3 Mpc (H_0 = 50 km/s/Mpc) in Coma. The radio map reveals clear similarities with images of the extended X-ray halo of the Coma clust

Esther M. Hu, Richard G. McMahon, Eiichi Egami

We present the results of ground-based and HST imaging studies targeted on z>4.5 quasar fields. High-redshift galaxies identified in deep narrow-band Lyman alpha images of the fields surrounding the quasars BR1202-0725 (z=4.694) and BR2237-0607 (z=4.558) have been confirmed with follow-up spectroscopy using the LRIS spectrograph on the Keck 10m telescope. Th

S. P. de Alwis

We show the complete cancellation of gauge and gravitational anomalies in the M-theory of Horava and Witten using their boundary contribution, and a term coming from the existence of two and five-branes. A factor of three discrepancy noted in an earlier work is resolved. We end with a comment on flux quantization.

A. A. Tseytlin

The condition of vanishing of static force on a q-brane probe in the gravitational background produced by another p-brane is used to give a simple derivation of the pair-wise intersection rules which govern the construction of BPS combinations of branes. These rules, while implied also by supersymmetry considerations, thus have purely bosonic origin. Imposin

David R. Morrison

Lecture notes from 1993 Park City lectures and 1994 Trento lectures. The focus of these lectures is on giving a mathematical description of the A-model and B-model correlation functions on a Calabi--Yau manifold, and a precise mathematical conjecture relating these for a pair of mirror manifolds.

D. Markovic, J. Sommer-Larsen

We study the accuracy of inference of the massive halo objects&#39; (MHO or `Macho&#39;) mass function from microlensing events observed toward LMC. Assuming the spatial distribution and kinematics of the objects are known, the slope and the range of the MHO mass function (modeled here by a simple power law) will be possible to determine from 100-1000 detect

S. Chandrasekharan, U. -J. Wiese

We construct lattice gauge theories in which the elements of the link matrices are represented by non-commuting operators acting in a Hilbert space. These quantum link models are related to ordinary lattice gauge theories in the same way as quantum spin models are related to ordinary classical spin systems. Here U(1) and SU(2) quantum link models are constru

L. Piccirillo, B. Femenia, N. Kachwala, R. Rebolo

First results of a Cosmic Microwave Background (CMB) anisotropy experiment conducted at the Observatorio del Teide (Tenerife, Spain) are presented. The instrument is a four channel (3.1, 2.1, 1.3 and 1.1 mm) $^3$He bolometer system coupled to a 45 cm diameter telescope. The resultant configuration is sensitive to structures on angular scales ~ 1-2 degrees. W

Masafumi Fukuma, Shigeaki Yahikozawa

We explicitly construct soliton operators in $D<2$ (or $c<1$) string theory, and show that the Schwinger-Dyson equations allow solutions with these solitons as backgrounds. The dominant contributions from 1-soliton background are explicitly evaluated in the weak coupling limit, and shown to agree with the nonperturbative analysis of string equations. We sugg

E. Leader, D. B. Stamenov

We demonstrate that the significant discrepancy between the previous predictions of the conventional QCD and the CDF inclusive jet production data could be an indication that the behaviour of the Callan-Symanzik βfunction in QCD corresponds to it having an ultraviolet finite fixed point.

I. Antoniadis, M. Quiros

We study strong coupling effects in four-dimensional heterotic string models where supersymmetry is spontaneously broken with large internal dimensions, consistently with perturbative unification of gauge couplings. These effects give rise to thresholds associated to the dual theories: type I superstring or M-theory. In the case of one large dimension, we fi

J. R. Cudell, I. Royen

We show that the lowest-order QCD calculation in a simple model of elastic vector-meson production does reproduce correctly the ratios of cross sections for rho, phi and J/psi, both in photoproduction and in high-Q2 quasi-elastic scattering. The dependence of the slopes on the mass of the vector meson is reproduced as well. We examine the lower-energy data,

Andrei Teleman

We introduce the concept of Spin^G-structure in a SO-bundle, where $G\subset U(V)$ is a compact Lie group containing $-id_V$. We study and classify $Spin^G(4)$-structures on 4-manifolds, we introduce the G-Monopole equations associated with a $Spin^G$-structure. On Kaehler surfaces a Kobayashi-Hitchin correspondence can be proved for the corresponding moduli

M. Ulmke, R. T. Scalettar, A. Nazarenko, E. Dagotto

Dynamic properties of the three-dimensional single-band Hubbard model are studied using Quantum Monte Carlo combined with the maximum entropy technique. At half-filling, there is a clear gap in the density of states and well-defined quasiparticle peaks at the top (bottom) of the lower (upper) Hubbard band. We find an antiferromagnetically induced weight abov

Andrew J. Bordner

One may obtain, using operator transformations, algebraic relations between the Fourier transforms of the causal propagators of different exactly solvable potentials. These relations are derived for the shape invariant potentials. Also, potentials related by real transformation functions are shown to have the same spectrum generating algebra with Hermitian g

C. Rocke, A. Wixforth, J. P. Kotthaus, H. Boehm

We report on recent experiments investigating the modification of the inter-band optical response of a piezoelectric semiconductor quantum well structure under the influence of intense short period surface acoustic waves. Experimentally, we study the photoluminescence (PL) of an undoped strained InGaAs/GaAs quantum well on which surface acoustic waves are pr

P. W. Brouwer, C. W. J. Beenakker

We compare two widely used models for dephasing in a chaotic quantum dot: The introduction of a fictitious voltage probe into the scattering matrix and the addition of an imaginary potential to the Hamiltonian. We identify the limit in which the two models are equivalent and compute the distribution of the conductance in that limit. Our analysis explains why

Laurent Baulieu, Nobuyoshi Ohta

We determine the equations which govern the gauge symmetries of worldsheets with local supersymmetry of arbitrary rank $(N,N&#39;)$, and their possible anomalies. Both classical and ghost conformally invariant multiplets of the left or right sector are assembled into the components of a single $O(N)$-superfield. The component with ghost number zero of this s

H. Grosse, E. Langmann, E. Raschhofer

We study the Luttinger-Schwinger model, i.e. the (1+1) dimensional model of massless Dirac fermions with a non-local 4-point interaction coupled to a U(1)-gauge field. The complete solution of the model is found using the boson-fermion correspondence, and the formalism for calculating all gauge invariant Green functions is provided. We discuss the role of an

Shuichi Murakami, Frank Göhmann

We develop the quantum inverse scattering method for the one-dimensional Hubbard model on the infinite interval at zero density. $R$-matrix and monodromy matrix are obtained as limits from their known counterparts on the finite interval. The $R$-matrix greatly simplifies in the considered limit. The new $R$-matrix contains a submatrix which turns into the ra

T. H. Baker, P. J. Forrester

The Schrödinger operators with exchange terms for certain Calogero-Sutherland quantum many body systems have eigenfunctions which factor into the symmetric ground state and a multivariable polynomial. The polynomial can be chosen to have a prescribed symmetry (i.e. be symmetric or antisymmetric) with respect to the interchange of some specified variables. Fo

Robert Bluhm, Alan Kostelecky, Bogdan Tudose

The revival structure of wave packets is examined for quantum systems having energies that depend on two nondegenerate quantum numbers. For such systems, the evolution of the wave packet is controlled by two classical periods and three revival times. These wave packets exhibit quantum beats in the initial motion as well as new types of long-term revivals. Th

K. C. Chase, A. Z. Mekjian, P. Meenakshisundaram

The thermal and statistical properties of hadronic matter under some extreme conditions are investigated using an exactly solvable canonical ensemble model. A unified model describing both the fragmentation of nuclei and the thermal properties of hadronic matter is developed. Simple expressions are obtained for quantities such as the hadronic equation of sta

C Alexa, D Vrinceanu

A very intuitive description of nucleus-nucleus collision phenomena is provided by the relativistic fluid dynamics. We consider a 1+1 dimensional relativistic imperfect fluid flow to approximate the high energy heavy ion collision. The article investigates the application of the continuous symmetry group on the relativistic fluid energy-momentum tensor conse

S. Quassowski, K. Hermann

LEED experiments show that Li adsorbed at Cu(100) surfaces at room temperature induces a (2x1) missing row substrate reconstruction while adsorption at lower temperatures, T=180 K, results in an unreconstructed Cu(100)+c(2x2)--Li overlayer structure. Substrate reconstruction has not been observed for Na nor for K adsorption. In order to study the specific re

Shobhana Narasimhan, Matthias Scheffler

We develop a model to study the thermal expansion of surfaces, wherein phonon frequencies are obtained from ab initio total energy calculations. Anharmonic effects are treated exactly in the direction normal to the surface, and within a quasiharmonic approximation in the plane of the surface. We apply this model to the Ag(111) and Al(111) surfaces, and find

Stefan Leupold

We present a complete set of Feynman rules for non-Abelian gauge fields obeying the radial (Fock-Schwinger) gauge condition and prove the consistency with covariant gauge Feynman rules.

G. H. Gadiyar

An essentially unique deformation of the product of quantum fields at the same spacetime point is obtained. It is proposed to replace local quantum field theory with another structure which uses a *-product. The resulting theory contains a fundamental length and is free from divergences. This provides the third deformation suggested by Faddeev.

Mary Alberg, Ernest M. Henley, Xiangdong Ji, A. W. Thomas

Flavor asymmetries for the valence and sea quarks of the $Σ^{\pm}$ can be obtained from Drell-Yan experiments using charged hyperon beams on proton and deuteron targets. A large, measurable difference in sea quark asymmetries is predicted between SU(3) and pseudoscalar meson models. The latter predict that in $Σ^{+}$, $\bar{u}/\bar{d} \leq 1/2$, whereas the

Sacha Davidson, Ralf Hempfling

We propose a mechanism for hiding the primordial baryon asymmetry from interactions that could wash it out. It requires the introduction of a baryon number carrying singlet which is in equilibrium in the early universe and shares any existing baryon asymmetry. It decouples from the Standard Model particles before all the interactions required to wash out the

P. H. Frampton, S. L. Glashow

We examine certain extensions of the standard model in which $CP$ violation is spontaneous and the strong $CP$ problem is resolved. In these models, the $3 \times 3$ quark mixing matrix is neither real nor unitary. However, to a precision of 0.1%, it is real and orthogonal. There are no readily observable $CP$-violating effects besides those in the neutral k

Loyal Durand, Phuoc Ha

We have analyzed the theory of the baryon magnetic moments in the approximate) QCD setting suggested by Brambilla et al. By modifying their derivation of the $qqq$ interaction and wave equation for baryons, we derived expressions for the baryon moments in terms of the underlying quark moments, including the first corrections associated with the binding of th

Utpal Sarkar

I propose a new mechanism for baryogenesis, in which the out-of-equilibrium condition is not neccessary. When the electroweak symmetry is broken spontaneously, left-handed neutrinos may get Majorana masses containing $CP-$violating phases. This induces a lepton asymmetry spontaneously, which is then converted to a baryon asymmetry in the presence of the spha

Yu. A. Golubkov

Using the statistical approach additional light partons have been introduced in the Intrinsic Charm model. Explicit expressions are obtained for charmed and light quark distributions. A comparison is made with standard IC model predictions. It is shown that such a modification of the IC model leads to better agreement with the $pN$ and $πN$ data on $\JP$ pro

Romuald A. Janik, Maciej A. Nowak, Gabor Papp, Jochen Wambach

Using the standard concepts of free random variables, we show that for a large class of nonhermitean random matrix models, the support of the eigenvalue distribution follows from their hermitean analogs using a conformal transformation. We also extend the concepts of free random variables to the class of nonhermitean matrices, and apply them to the models di