December 1993 arXiv papers — page 5

Hyunggyu Park

We study a monomer-dimer model with repulsive interactions between the same species in one dimension. With infinitely strong interactions the model exhibits a continuous transition from a reactive phase to an inactive phase with two equivalent absorbing states. Monte Carlo simulations show that the critical behavior is different from the conventional directe

David Band

I consider the effect of repeating gamma ray burst sources on the <V/Vmax> statistic. I find that the treatment of repeating events, if applied consistently, will not affect the effectiveness of <V/Vmax> as a test of burst homogeneity. The calculation of <V/Vmax> for apparent repeating and nonrepeating source populations will be biased by the incorrect class

F. Bernardeau

In this paper, I present the calculation of the third and fourth moments of both the distribution function of the large--scale density and the large--scale divergence of the velocity field, $θ$. These calculations are made by the mean of perturbative calculations assuming Gaussian initial conditions and are expected to be valid in the linear or quasi linear

Vladimir V. Usov

Relativistic electron-positron winds with strong magnetic fields are considered as a source of radiation for cosmological $γ$-ray bursters. Such a wind is generated by a millisecond pulsar with a very strong magnetic field. An electron-positron plasma near the pulsar is optically thick and in quasi-thermodynamic equilibrium. It is shown that the main part of

G. J. Chaitin

A remarkable new definition of a self-delimiting universal Turing machine is presented that is easy to program and runs very quickly. This provides a new foundation for algorithmic information theory. This new universal Turing machine is implemented via software written in Mathematica and C. Using this new software, it is now possible to give a self-containe

Edi Halyo

We show that there can be TeV scale scalar and fermionic leptoquarks with very weak Yukawa couplings in a generic standard--like superstring model. Leptoquark--(down--like) quark mixing though present, is not large enough to violate the unitarity bounds on the CKM matrix. The constraints on leptoquark masses and couplings from FCNCs are easily satisfied wher

M. Bourdeau, M. R. Douglas

We discuss the large $N$ limit of the supersymmetric $CP^N$ models as an illustration of Cecotti and Vafa&#39;s $tt^*$ formalism. In this limit the `$tt^*$ equation&#39; becomes the long wavelength limit of the $2D$ Toda lattice, an equation first studied in the context of self-dual gravity. We show how simple finite temperature and large $N$ techniques dete

Wenbin, David G. Stroud

The dynamical response of triangular JJA is investigated using the RCSJ model. A flux flow regime is found to extend between a lower vortex-depinning current and a higher critical current, in agreement with previous calculations for square arrays. In the flux flow regime, the dynamical response to the bias current is roughly Ohmic, and the time-dependent vol

Stacy McGaugh

OBSERVATIONS of galaxies to very faint magnitudes have revealed a population of blue galaxies at intermediate redshift$^{1-5}$. These galaxies represent a significant excess over the expectation of standard cosmological models for reasonable amounts of evolution of the locally observed galaxy population. However, the surveys which define the local galaxy pop

David H Lyth

These notes form an introduction to cosmology with special emphasis on large scale structure, the cmb anisotropy and inflation. In some places a basic familiarity with particle physics is assumed, but otherwise no special knowledge is needed. Most of the material in the first two sections can be found in several texts, except that the discussion of dark matt

E. Aldrovandi, G. Falqui

We discuss geometrical aspects of Higgs systems and Toda field theory in the framework of the theory of vector bundles on Riemann surfaces of genus greater than one. We point out how Toda fields can be considered as equivalent to Higgs systems -- a connection on a vector bundle $E$ together with an End($E$)--valued one form both in the standard and in the Co

J. de Boer, K. Clubok, M. B. Halpern

Halpern and Yamron have given a Lorentz, conformal, and Diff S$_2$-invariant world-sheet action for the generic irrational conformal field theory, but the action is highly non-linear. In this paper, we introduce auxiliary fields to find an equivalent linearized form of the action, which shows in a very clear way that the generic affine-Virasoro action is a D

Yun Wang

This revised version uses Gauss-Codazzi equations to derive the exact mass and radius relations. The results remain qualitatively the same.

M. Sawicki, D. V. Ahluwalia

By considering the parity-transformation properties of the $(1/2,\,0)$ and $(0,\,1/2)$ fields in the {\it front form} we find ourselves forced to study the front-form evolution both along $x^+$ and $x^-$ directions. As a by product, we find that half of the dynamical degrees of freedom of a full theory live on the $x^+=0$ surface and the other half on the $x

D. V. Ahluwalia, T. Goldman, M. B. Johnson

This is second of the two invited lectures presented (by D. V. Ahluwalia) at the ``XVII International School of Theoretical Physics: Standard Model and Beyond&#39; 93.&#39;&#39; The text is essentially based on a recent publication by the present authors [Mod. Phys. Lett. A (in press)]. Here, after briefly reviewing the $(j,0)\oplus(0,j)$ Dirac-like construc

D. V. Ahluwalia, M. B. Johnson, T. Goldman

This is first of the two invited lectures presented (by D. V. Ahluwalia) at the ``XVII International School of Theoretical Physics: Standard Model and Beyond&#39; 93.&#39;&#39; The text is essentially based on a recent publication by the present authors [Phys. Lett. B 316 (1993) 102]. Here we show that the Dirac-like construct in the $(j,0)\oplus(0,j)$ repre

D. V. Ahluwalia, M. B. Jonnson, T. Goldman

We begin with a few remarks on an explicit construction of a Bargmann-Wightman-Wigner-type quantum field theory [Phys. Lett. B {\bf 316}, 102 (1993)] in which bosons and associated antibosons have opposite relative intrinsic parities. We then construct $(1,0)\oplus(0,1)$ Majorana ($CP$ self conjugate) and Majorana-like ($CΓ^5$ self conjugate, $Γ^5=$ chiralit

Oleg A. Fonarev

We analyse quantum--kinetic effects in the early Universe. We show that quantum corrections to the Vlasov equation give rise to a dynamical variation of the gravitational constant. The value of the gravitational constant at the Grand Unification epoch is shown to differ from its present value to about $10^{-4} ÷10^{-3} \% $.

K. Lee

We discuss the low-temperature specific heat of the integrable SU(N)- invariant Heisenberg model in one dimension with degrees of freedom in the symmetric rank-$m$ tensor representation, especially for the antiferromagnetic coupling. It is known that the linear specific heat coefficient $\gam$ is a function of a field which breaks the SU(N) invariance of the

Che Ming Ko, David Seibert

The decay width of a phi meson is reduced from its vacuum value as its mass decreases in hot hadronic matter as a result of the partial restoration of chiral symmetry. This reduction is, however, cancelled by collisional broadening through the reactions $ϕπ\to KK^*$, $ϕK\toϕK$, $ϕρ\to KK$, and $ϕϕ\to KK$. The resulting phi meson width in hot hadronic matter

Georg Raffelt, David Seckel

The problem of neutral-current processes (neutrino scattering, pair emission, pair absorption, axion emission, \etc) in a nuclear medium can be separated into an expression representing the phase space of the weakly interacting probe, and a set of dynamic structure functions of the medium. For a non-relativistic medium we reduce the description to two struct

A. Boresch, M. Schweda, S. P. Sorella

The vector supersymmetry recently found for the bosonic string is generalized to superstring theories quantized in the super-Beltrami parametrization.

A. Mikhailov

The representation of scalar products of Bethe wave functions in terms of the Dual Fields, proven by A.G.Izergin and V.E.Korepin in 1987, plays an important role in the theory of completely integrable models. The proof in \cite{Izergin87} and \cite{Korepin87} is based on the explicit expression for the &#34;senior&#34; coefficient which was guessed in \cite{

H. J. de Vega, J. Ramírez Mittelbrunn, M. Ramón Medrano, N. Sánchez

The exact general solution for a sigma model having the $2-d$ stringy black hole (SBH) as internal manifold is found in closed form. We also give the exact solution for the massless complex Sine-Gordon (MCSG) model. Both, models and their solutions are related by analytic continuation. The solution is expressed in terms of four arbitrary functions of one var

Henrique Boschi-Filho

Using the heat kernel regularization we show that the Abelian chiral anomaly in the limit of infinite temperature it is not a well defined quantity, contrary to what happens at any finite temperature. We show that there is an ambiguity in the ordering of the limits of infinite temperature and removal of the cut-off so that changing this ordering we find diff

Andreas W. Wipf

The main goal of these lectures is to introduce and review the Hamiltonian formalism for classical constrained systems and in particular gauge theories. Emphasis is put on the relation between local symmetries and constraints and on the relation between Lagrangean and Hamiltonian symmetries.

Csaba Csaki, Lisa Randall

The ACCMM model predicts the lepton spectrum from $B$ meson decay by assuming the meson disintegrates into a spectator quark of definite mass and momentum distribution and an off shell $b$ quark whose decay leptons (boosted into the rest frame of the meson) determine the lepton spectrum. In this letter, we show that one can define a model dependent $b$ quark

Hai Ren

We study the scattering of fermions in a ``global monopole&#39;&#39; background metric. This is the four-dimensional analogue of the scattering on a cone in three dimensions. The scattering amplitude is exactly obtained. We then study massless fermion-dyon systems in such a background metric. The density of the $S$-wave fermion condensate is found to be give

Hai Ren

We find general, time-dependent solutions produced by open string sources carrying no momentum flow in 2+1 dimensional gravity. The local Poincaré group elements associated with these solutions and the coordinate transformations that transform these solutions into Minkowski metric are obtained. We also find the relation between these solutions and the planar

R. Montagne, A. Amengual, E. Hernandez-Garcia, M. San Miguel

The dynamics of transient patterns formed by front propagation in extended nonequilibrium systems is considered. Under certain circumstances, the state left behind a front propagating into an unstable homogeneous state can be an unstable periodic pattern. It is found by a numerical solution of a model of the Fréedericksz transition in nematic liquid crystals

G. I. Poulis, T. W. Donnelly

We extend the relativistic plane--wave impulse approximation formalism to incorporate a specific class of relativistic interference effects for use in describing inclusive electrodisintegration of $^2$H. The role of these ``exchange&#39;&#39; terms for the various response functions accessible in parity--conserving and --violating inclusive processes is inve

Boris Khesin, Ilya Zakharevich

We introduce a Lie bialgebra structure on the central extension of the Lie algebra of differential operators on the line and the circle (with scalar or matrix coefficients). This defines a Poisson--Lie structure on the dual group of pseudodifferential symbols of an arbitrary real (or complex) order. We show that the usual (second) Benney, KdV (or GL_n--Adler

H. J. de Vega

This is a review on infinite non-abelian symmetries in two-dimensional field theories. We show how any integrable QFT enjoys the existence of infinitely many {\bf conserved} charges. These charges {\bf do not commute} between them and satisfy a Yang--Baxter algebra. They are generated by quantum monodromy operators and provide a representation of $q-$deforme

Z. Kopecky

The dilaton free energy density in external static gravitational field is found. We use the real time formulation of the finite temperature field theory and the free energy density is computed to the first order of the string parameter $α&#39;$. We obtain the thermal corrections to the $α&#39;$ modified Einstein gravity action.

A. T. Filippov, A. B. Kurdikov

This is a brief review of our recent work attempted at a generalization of the Grassmann algebra to the paragrassmann ones. The main aim is constructing an algebraic basis for representing `fractional&#39; symmetries appearing in $2D$ integrable models and also introduced earlier as a natural generalization of supersymmetries. We have shown that these algebr

J. S. Dowker

The scalar functional determinants on sectors of the two-dimensional disc and spherical cap are determined for arbitrary angles (rational factors of $π$). The wholesphere and hemisphere expressions are also given, in low dimensions, for both the ordinary and the conformal Laplacian. Comparisons are made with other work.

Takashi Suzuki

Highest weight representations of $U_q(su(1,1))$ with $q=\exp πi/N$ are investigated. The structures of the irreducible hieghesat weight modules are discussed in detail. The Clebsch-Gordan decomposition for the tensor product of two irreducible representations is discussed. By using the results, a representation of $SL(2,R)\otimes U_q(su(2))$ is also present

Rulin Xiu

The derived modular invariant one-loop string effective coupling constant has been used to discuss the weak scale measurement constraints on minimal superstring models, minimal SUSY left-right string models and minimal left-right SUSY string models. The string intermediate gauge symmetry breaking models are proposed. The possible schemes to predict $M_{GUT}

Peter Schupp

A Cartan Calculus of Lie derivatives, differential forms, and inner derivations, based on an undeformed Cartan identity, is constructed. We attempt a classification of various types of quantum Lie algebras and present a fairly general example for their construction, utilizing pure braid methods, proving orthogonality of the adjoint representation and giving

Peter Schupp

The topic of this thesis is the development of a versatile and geometrically motivated differential calculus on non-commutative or quantum spaces, providing powerful but easy-to-use mathematical tools for applications in physics and related sciences. A generalization of unitary time evolution is proposed and studied for a simple 2-level system, leading to no

Peter Schupp, Paul Watts, Bruno Zumino

A generalization of the differential geometry of forms and vector fields to the case of quantum Lie algebras is given. In an abstract formulation that incorporates many existing examples of differential geometry on quantum spaces we combine an exterior derivative, inner derivations, Lie derivatives, forms and functions all into one big algebra, the ``Cartan

P. A. Griffin, M. Masip, M. McGuigan

We use heavy quark effective theory (HQET) and perturbative QCD to study the heavy meson -- light vector meson transitions involved in D and B decays. HQET is used to relate the measured D -> K* l nu vector and axial-vector form factors at four-momentum transfer q^2 = 0 to the B -> K* gamma tensor and axial-tensor form factors at q^2 = 16.5 GeV^2. Perturbati

R. D. Ball, G. Ripka

The momentum dependence of the quark self energy gives a physically motivated and consistent regularization of both the real and imaginary parts of the quark loop contribution to the meson action. We show that the amplitudes for anomalous processes are always reproduced correctly.

G. Mangano, G. Miele, G. Migliore

Starting from the old idea that Fermi statistics for quarks play a fundamental role to explain some features of hadron structure, we study the modification of the scaling behaviour of parton distributions due to quantum statistical effects. In particular, by following an interesting formal analogy which holds between the Altarelli-Parisi evolution equations,

P. Colangelo, P. Santorelli

We use QCD sum rules to analyze the semileptonic transition $B \to π\ell ν$ in the limit $m_b \to \infty$. We derive the dependence of the form factor $F_1(0)$ on the heavy quark mass, which is compatible with the expected dependence for the simple pole model of $F_1(q^2)$.

John P. Costella, Bruce H. J. McKellar

We show that it is possible to obtain self-consistent and physically acceptable relativistic classical equations of motion for a point-like spin-half particle possessing an electric charge and a magnetic dipole moment, directly from a manifestly covariant Lagrangian, if the classical degrees of freedom are appropriately chosen. It is shown that the equations

V. L. Eletsky, Ian I. Kogan

The Goldberger-Treiman relation is shown to persist in the chiral limit at finite temperatures to order $O(T^2)$. The $T$ dependence of $g_A$ turns out to be the same as for $F_{\pi}$, $g_{A}(T)=g_{A}(0)(1-T^2/12F^2)$, while $g_{\pi NN}$ is temperature independent to this order. The baryon octet ${\cal D}$ and ${\cal F}$ couplings also behave as $F_{\pi}$ if

Z. Burda, J. Wosiek

A new method for locating analytically critical temperatures is discussed. It is exact for selfdual systems. When applied the two coupled layers of Ising spins it deviates from our preliminary Monte Carlo estimates by 1.5 standard deviations. It predicts critical temperature of the three dimensional Ising model in terms of the solution of the two layer Ising

G. Bhanot, M. Creutz, U. Glaessner, K. Schilling

We compute high temperature expansions of the 3-d Ising model using a recursive transfer-matrix algorithm and extend the expansion of the free energy to 24th order. Using ID-Pade and ratio methods, we extract the critical exponent of the specific heat to be alpha=0.104(4).

C. T. Sachrajda

It is shown that the renormalisation constants of two quark operators can be accurately determined (to a precision of a few per-cent using 18 gluon configurations) using Chiral Ward identities. A method for computing renormalisation constants of generic composite operators without the use of lattice perturbation theory is proposed.

Anthony Duncan, Estia Eichten, Jonathan M. Flynn, Brian R. Hill

We present results for f_B and masses of low-lying heavy-light mesons. Calculations were performed in the quenched approximation using multistate smearing functions generated from a spinless relativistic quark model Hamiltonian. Beta values range from 5.7 to 6.3, and light quark masses corresponding to pion masses as low as 300 MeV are computed at each value

Sergei E. Esipov

We present a study of the Burgers equation in one and two dimensions $d=1,2$ following the analytic approach indicated in the previous paper I. For the problem of the initial conditions decay we consider two classes of initial condition distributions $Q_{1,2} \sim \exp[-(1/4D)\int({\nabla}h)^2$d{\bf x}] where $h$-field is unbounded ($Q_1$) or bounded ($Q_2,

Volker Bach, Elliott H. Lieb, Jan philip Solovej

The familiar unrestricted Hartree-Fock variational principle is generalized to include quasi-free states. As we show, these are in one-to-one correspondence with the one-particle density matrices and these, in turn provide a convenient formulation of a generalized Hartree-Fock variational principle, which includes the BCS theory as a special case. While this

T. Karapiperis, B. Blankleider

The transport and chemical reactions of solutes are modelled as a cellular automaton in which molecules of different species perform a random walk on a regular lattice and react according to a local probabilistic rule. The model describes advection and diffusion in a simple way, and as no restriction is placed on the number of particles at a lattice site, it

G. D. Starkman, N. Kaiser, R. A. Malaney

We investigate the production of dark matter with non-standard momentum distributions arising from the decay of a relativistic massive neutrino into a lighter fermion and boson H$\rightarrow$F$+$B. We develop the Boltzmann equations for this process, paying particular attention to spin polarisation effects. Such decays can, under certain circumstances, lead

Douglas C. Heggie

Gravothermal oscillations occur in several models for the post-collapse evolution of rich star clusters. This paper reviews the main literature, and presents some new N-body results which appear to exhibit this phenomenon.

John Little

A canonically-embedded curve of genus $g$ is a pure 1-dimensional, non-degenerate subscheme $C$ of ${\bf P}^{g-1}$ over an algebraically closed field $k$, for which ${\cal O}_C(1) \cong ω_C$, (the dualizing sheaf)$ and $h^0(C, {\cal O}_C) = 1$, $h^0(C, ω_C) = g$. The singularities of $C$ (if any) are Gorenstein, and $C$ is connected of degree $2g-2$ and arit

James A. Bryan, Sean M. Carroll, Ted Pyne

Textures are topologically nontrivial field configurations which can exist in a field theory in which a global symmetry group $G$ is broken to a subgroup $H$, if the third homotopy group $\p3$ of $G/H$ is nontrivial. We compute this group for a variety of choices of $G$ and $H$, revealing what symmetry breaking patterns can lead to texture. We also comment o

X. -G. Zhao, R. Jahnke, Q. Niu

A single band in a spatially periodic system splits into a series of quasienergy subbands under the action of DC--AC electric fields. These dynamic fractional Stark ladders should be observable in an investigation of optical absorption.

MI Dykman, DG Luchinsky, R Mannella, PVE McClintock

It is demonstrated, by means of analogue electronic simulation and theoretically, that external noise can markedly change the character of the response of a nonlinear system to a low-frequency periodic field. In general, noise of sufficient intensity {\it linearises} the response. For certain parameter ranges in particular cases, however, an increase in the

Terrence Draper, Craig McNeile

We introduce an acceleration algorithm for coulomb gauge fixing, using the compactly supported wavelets introduced by Daubechies. The algorithm is similar to Fourier acceleration. Our provisional numerical results for $SU(3)$ on $8^{4}$ lattices show that the acceleration based on the DAUB6 transform can reduce the number of iterations by a factor up to 3 ov

T. Blum, Leo Karkkainen

We experiment with adding dynamical gauge field to Kaplan (defect) fermions. In the case of U(1) gauge theory we use an inhomogenous Higgs mechanism to restrict the 3d gauge dynamics to a planar 2d defect. In our simulations the 3d theory produce the correct 2d gauge dynamics. We measure fermion propagators with dynamical gauge fields. They posses the correc

Igor Halperin

It is argued that an account for the Veneziano ghost pole, appearing in resolving the U(1) problem, is necessary for understanding an isospin violation in the $ π- η- η&#39; $ system. By virtue of a perturbative expansion around the $ SU(2)_{V} $ ( $ m_{u} = m_{d} $ ) symmetric Veneziano solution, we find that the ghost considerably suppresses isospin breaki

Steven Detweiler

This revision includes clarified exposition and simplified analysis. Solutions of the Einstein equations which are periodic and have standing gravitational waves are valuable approximations to more physically realistic solutions with outgoing waves. A variational principle is found which has the power to provide an accurate estimate of the relationship betwe

D. Metzger, H. Meyer--Ortmanns, H. --J. Pirner

The temperature behaviour of meson condensates $<σ_0>$ and $<σ_8>$ is calculated in the $SU(3)\times SU(3)$-linear sigma model. The couplings of the Lagrangian are fitted to the physical $π,K,η,η&#39;$ masses, the pion decay constant and a $O^+(I=0)$ scalar mass of $m_σ=1.5$ GeV. The quartic terms of the mesonic interaction are converted to a quadratic term

G. Peilert, T. C. Sangster, M. N. Namboodiri, H. C. Britt

The reduced velocity correlation function for fragments from the reaction Fe + Au at 100 A~MeV bombarding energy is investigated using the dynamical--statistical approach QMD+SMM and compared to experimental data to extract the Freeze--Out volume assuming simultaneous multifragmentation.

Chan Hong-Mo, J. Faridani, Tsou Sheung Tsun

Abstrac: It is shown that an antisymmetric rank-two tensor gauge potential of the type first found in string and supersymmetry theories occurs also in ordinary Yang-Mills theory when formulated in loop space, where it appears as a Lagrange multiplier for a zero curvature constraint necessary and sufficient for removing the inherent redundancy of loop variabl

Chan Hong-Mo, J. Faridani, Tsou Sheung Tsun

Most nonabelian gauge theories admit the existence of conserved and quantized topological charges as generalizations of the Dirac monopole. Their interactions are dictated by topology. In this paper, previous work in deriving classical equations of motion for these charges is extended to quantized particles described by Dirac wave functions. The resulting eq

J. C. Brunelli, Ashok Das

We derive the two equations of Davey-Stewartson type from a zero curvature condition associated with SL(2,{\bf R}) in $2+1$ dimensions. We show in general how a $2+1$ dimensional zero curvature condition can be obtained from the self-duality condition in $3+3$ dimensions and show in particular how the Davey-Stewartson equations can be obtained from the self-

M. V. Cougo-Pinto, C. Farina, Antonio J. Segui-Santonja

After briefly reviewing how the (proper-time) Schwinger&#39;s formula works for computing the Casimir energy in the case of &#34;scalar electrodynamics&#34; where the boundary conditions are dictated by two perfectly conducting parallel plates with separation &#34;a&#34; in the Z-axis, we propose a slightly modification in the previous approach based on an a

Jerzy Lukierski, Henri Ruegg, Valerij N. Tolstoy, Anatol Nowicki

We consider the twisting of Hopf structure for classical enveloping algebra $U(\hat{g})$, where $\hat{g}$ is the inhomogenous rotations algebra, with explicite formulae given for $D=4$ Poincaré algebra $(\hat{g}={\cal P}_4).$ The comultiplications of twisted $U^F({\cal P}_4)$ are obtained by conjugating primitive classical coproducts by $F\in U(\hat{c})\otim

Toshihiro Sasada

We study whether orbifold models are equivalently rewritten into torus models in the case of fermionic string theories. It is pointed out that symmetric orbifold models cannot be rewritten into torus models in the case of fermionic string theories because of the absence of twist-untwist intertwining currents on the orbifold models. We present a list of curre

Victor G. Kac, Weiqiang Wang

After giving some definitions for vertex operator SUPERalgebras and their modules, we construct an associative algebra corresponding to any vertex operator superalgebra, such that the representations of the vertex operator algebra are in one-to-one correspondence with those of the corresponding associative algebra. A way is presented to decribe the fusion ru

Prem P. Srivastava

The field theory quantized on the {\it light-front} is compared with the conventional equal-time quantized theory. The arguments based on the {\it microcausality} principle imply that the light-front field theory may become nonlocal with respect to the longitudinal coordinate even though the corresponding equal-time formulation is local. This is found to be

L. Lavoura

In the SUSY GUT scenario, it is natural to assume the right-handed-neutrino Majorana-mass scale to be $10^{16}$ GeV. This will in principle lead, by the seesaw mechanism, to a $ ν_τ $ mass of order $ m_t^2 / (10^{16}\, {\rm GeV}) \sim 3 \times 10^{-3}\, {\rm eV} $. This suggests that the solution of the solar-neutrino puzzle should be either the MSW effect i

A. B. Lahanas, K. Tamvakis, N. D. Tracas

We compute one loop radiative corrections to the physical neutralino masses in the MSSM considering the dominant top-stop contributions. We present a numerical renormalization group analysis of the feasibility of the radiative gauge symmetry breaking parametrized by the standard soft supersymmetry breaking terms. Although the above computed effects can be in

R. Delbourgo, Dongsheng Liu

Lorentz covariant wave functions for meson and baryon supermultiplets are simply derived by boosting $SU(2)_J$ representations corresponding to multiquark systems at rest.

W. Janke, T. Sauer

We report tests of the recently proposed multicanonical multigrid Monte Carlo method for the two-dimensional $Φ^4$ field theory. Defining an effective autocorrelation time we obtain real time improvement factors of about one order of magnitude compared with standard multicanonical simulations.

A. S. Kronfeld, B. P. Mertens

The renormalization of a general action for massive lattice fermions is discussed. The analysis applies for all $m_q a$. Preliminary results for the self energy at one loop in perturbation theory are presented.

H. Dilger, H. Joos

We compare continuum and lattice formulation of the geometric Schwinger Model on the torus. The lattice reproduces the $U(1)_A$ anomaly, related to non-trivial topological gauge configurations and zero modes.

J. Westphalen, F. Zimmermann, M. Goeckeler, H. A. Kastrup

Using Luescher&#39;s method we determine the elastic scattering phases in the broken phase of the 4-dimensional O(4) non-linear sigma-model from the two-particle energy spectrum in a Monte-Carlo study on finite lattices. In the isospin-0-channel we observe the sigma-resonance and extract its mass and its width. In all scattering channels investigated the res

Istvan Montvay

Gribov copies of the vacuum in two dimensional compact U(1) lattice gauge models are constructed. On the basis of this a gauge fixing algorithm is developped, wich finds the minimum of the sum of link field squares. Numerical experience in a two dimensional Higgs model with fixed length scalar field is reported and the extension to three and four dimensional

J. W. Moffat

A possible resolution of the information loss paradox for black holes is proposed in which a phase transition occurs when the temperature of an evaporating black hole equals a critical value, $T_c$, and Lorentz invariance and diffeomorphism invariance are spontaneously broken. This allows a generalization of Schrödinger&#39;s equation for the quantum mechani

C. Kiefer

A detailed review is given of the semiclassical approximation to quantum gravity in the canonical framework. This includes in particular the derivation of the functional Schrödinger equation and a discussion of semiclassical time as well as the derivation of quantum gravitational correction terms to the Schrödinger equation. These terms are used to calculate

E. Z. Kuchinskii, M. V. Sadovskii

It is shown that the anomalous temperature dependence of the orbital part of the upper critical field $H_{c2}$ observed for epitaxially grown films of high-temperature superconductor $Bi-Sr-Cu-O$ (in wide temperature interval) can be satisfactorily explained by the influence of localization effects in two-dimensional (quasi-two-dimensional) case.

Yeong-Lieh Lin, Franco Nori

The recursion and path-integral methods are applied to analytically study the electronic structure of a neutral $C_{60}$ molecule. We employ a tight-binding Hamiltonian which considers both the $s$ and $p$ valence electrons of carbon. From the recursion method, we obtain closed-form {\it analytic} expressions for the $π$ and $σ$ eigenvalues and eigenfunction

Yeong-Lieh Lin, Franco Nori

We study the electronic states of giant single-shell and the recently discovered nested multi-shell carbon fullerenes within the tight-binding approximation. We use two different approaches, one based on iterations and the other on symmetry, to obtain the $π$-state energy spectra of large fullerene cages: $C_{240}$, $C_{540}$, $C_{960}$, $C_{1500}$, $C_{2160

Denis Ullmo, Klaus Richter, Rodolfo A. Jalabert

We calculate the magnetic response of ensembles of small two-dimensional structures at finite temperatures. Using semiclassical methods and numerical calculation we demonstrate that only short classical trajectories are relevant. The magnetic susceptibility is enhanced in regular systems, where these trajectories appear in families. For ensembles of squares

Michael Teitelman

The low-temperature free energy of the spin S quantum Heisenberg ferromagnetic chain in a strong magnetic field is obtained in a two-particle approximation by using exact solution of two-spin-wave problem. The result is beyond the perturbation theory because it incorporates the both bound and scattering state contributions, and the scattering effect is essen

A. Polishchuk

The following corollary has been added: for general tetragonal curve $C$ of genus $g\ge 9$ the homogeneous coordinate ring of $C$ defined by the line bundle $K(-T)$, where $K$ is the canonical class, $T$ is the tetragonal series, is Koszul. Also some misprints are corrected.

Damien Pierce, Aris Papadopoulos

We determine the neutralino and chargino masses in the MSSM at one-loop. We perform a Feynman diagram calculation in the on-shell renormalization scheme, including quark/squark and lepton/slepton loops. We find generically the corrections are of order 6%. For a 20 GeV neutralino the corrections can be larger than 20%. The corrections change the region of $μ,

Imre M. Jánosi, Gábor Vattay

In this work we compare the spectral properties of the daily medium temperature fluctuations with the experimental results of the Chicago Group, in which the local temperature fluctuations were measured in a helium cell. The results suggest that the dynamics of the daily temperature fluctuations is determined by the oft turbulent state of the atmospheric bou

K. R. Bell, D. N. C. Lin

One dimensional, convective, vertical structure models and one dimensional, time dependent, radial diffusion models are combined to create a self-consistent picture in which FU~Orionis outbursts occur in young stellar objects (YSOs) as the result of a large scale, self-regulated, thermal ionization instability in the surrounding protostellar accretion disk.

M. A. Alberg, E. M. Henley, L. Wilets, P. D. Kunz

A quark model which includes both scalar and vector contributions to the reaction mechanism (SV quark model) is used in a DWBA calculation of $\bar ΛΛ$ production in $\bar p p$ interractions. Total and differential cross-sections, polarizations, depolarizations, and spin-correlattion coefficients are computed for laboratory momenta from threshold to 1695 MeV

Abbas Ali, Avinash Khare

We point out that in a recent paper by Chaichian et al. (Phys. Rev.Lett71(1993)3405) Dirac quantization procedure is not properly followed as a result of which the resulting quantum theory is different from what one will get by a straightforward application of Dirac&#39;s formulation. For example at quantum level the model in I has noncommutative geometry, i

Silvio J. Rabello, Arvind N. Vaidya, Luiz Claudio M. de Albuquerque

We study the thermal behavior of the negative dimensional harmonic oscillator of Dunne and Halliday that at zero temperature, due to a hidden BRST symmetry of the classical harmonic oscillator, is shown to be equivalent to the Grassmann oscillator of Finkelstein and Villasante. At finite temperature we verify that although being described by Grassmann number

L. V. Avdeev, M. V. Chizhov

We present a simple renormalizable abelian gauge model which includes antisymmetric second-rank tensor fields as matter fields rather than gauge fields known for a long time. The free action is conformally rather than gauge invariant. The quantization of the free fields is analyzed and the one-loop renormalization-group functions are evaluated. Transverse fr

V. I. Man&#39;ko

The generalised quasienergy states are introduced as eigenstates of the new integral of motion for periodically and nonperiodically kicked quantum systems.The photon distribution function of polymode generalised correlated light expressed in terms of multivariable Hermite polynomials is discussed and the relation of its properties to Schrodinger uncertainty

Atsuo Kuniba

Eigenvalues of the commuting family of transfer matrices are expected to obey the $T$-system, a set of functional relation, proposed recently. Here we obtain the solution to the $T$-system for $C^{(1)}_2$ vertex models. They are compatible with the analytic Bethe ansatz and Yang-Baxterize the classical characters.

Noriaki Ikeda

We review nonlinear gauge theory and its application to two-dimensional gravity. We construct a gauge theory based on nonlinear Lie algebras, which is an extension of the usual gauge theory based on Lie algebras. It is a new approach to generalization of the gauge theory. The two-dimensional gravity is derived from nonlinear Poincar{\&#39; e} algebra, which