March 1993 arXiv papers — page 3

Andrzej J. Buras, Matthias Jamin, Markus E. Lautenbacher

We use the recently calculated two--loop anomalous dimensions of current-current operators, QCD and electroweak penguin operators to construct the effective Hamiltonian for $ΔS=1$ transitions beyond the leading logarithmic approximation. We solve the renormalization group equations and give the numerical values of Wilson coeff. functions. We propose a new se

B. E. Hanlon, G. C. Joshi

We discuss the derivation of $SO(10)$ G.U.T. models from higher dimensional theories with intermediate breaking scales. We then present models based on the Coset Space Dimensional Reduction Scheme with intermediate symmetry breaking induced by four fermion condensates.

A. K. De, E. Focht, W. Franzki, J. Jersak

We investigate on the lattice the Yukawa models in 2 dimensions with Z(2) and U(1) symmetries. These models reduce to the usual and chiral Gross-Neveu models, respectively, when the kinetic and the selfcoupling terms of the scalar field are turned off. The numerical data and mean field arguments suggest that, at least for some range of the scalar field hoppi

Luca Amendola, Diego Bellisai, Franco Occhionero, Rome Astronomical Observatory

A generic outcome of theories with scalar-tensor coupling is the existence of inflationary attractors, either power-law or de Sitter. The fluctuations arising during this phase are Gaussian and their spectrum depends on the wavenumber $k$ according to the power-law $k^{1/(1-p)}$, where $p$ is the inflationary power-law exponent. We investigate to which exten

J. Twamley

We study the decoherence properties of a certain class of Markovian quantum open systems from both the Decohering Histories and Environment Induced Superselection paradigms. The class studied includes many familiar quantum optical cases. For this class, we show that there always exists a basis which leads to {\em exactly} consistent histories for any coarse

John L. Cardy, Anthony J. Guttmann

We give exact relations for a number of amplitude combinations that occur in the study of self-avoiding walks, polygons and lattice trails. In particular, we elucidate the lattice-dependent factors which occur in those combinations which are otherwise universal, show how these are modified for oriented lattices, and give new results for amplitude ratios invo

C. A. Stafford

The low-temperature thermoelectric power of the repulsive-interaction one-dimensional Hubbard model is calculated using an asymptotic Bethe ansatz for holons and spinons. The competition between the entropy carried by the holons and that carried by the backflow of the spinons gives rise to an unusual temperature and doping dependence of the thermopower which

D. Mandrus, Michael C. Martin, C. Kendziora, D. Koller

We report far infrared transmission measurements on single crystal samples derived from Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$. The impurity scattering rate of the samples was varied by electron-beam irradiation, 50MeV $^{16}$O$^{+6}$ ion irradiation, heat treatment in vacuum, and Y doping. Although substantial changes in the infrared spectra were produced, in no

D. C. Heggie, N. Ramamani

This paper generalises King's models for tidally truncated star clusters by including approximately the non-spherical symmetry of the tidal field and the resulting non-spherical distortion of the cluster.

Vidyut Jain, Aris Papadopoulos

We study the 3d effective field theory of a weakly coupled two Higgs-doublet scalar model at high temperature. Our model has three scalar quartic couplings and an $O(4)$ symmetry which is spontaneously broken by a nonzero scalar field $vev$ at zero temperature. Using high temperature perturbation theory, renormalization group arguments in $4-ε$ dimensions, a

C. Ciofi degli Atti, S. Scopetta, E. Pace, G. Salme

It is shown that the nuclear effects playing a relevant role in Deep Inelastic Scattering of polarized electrons by polarized $^3$He are mainly those arising from the effective proton and neutron polarizations generated by the $S'$ and $D$ waves in $^3$He. A simple and reliable equation relating the neutron, $g_1^n$, and $^3$He, $g_1^3$, spin structure f

Malcolm N. Butler, Martin J. Savage, Roxanne P. Springer

We compute the branching ratio for $Δ\rightarrow Ne^+e^-$ and $Δ\rightarrow Nμ^+μ^-$ in chiral perturbation theory and find that both decays should be observable at CEBAF. With sufficiently low thresholds on the $e^+e^-$ invariant mass a branching ratio of $\sim 10^{-5}$ may be observed for $Δ\rightarrow Ne^+e^-$. For the $Δ\rightarrow Nμ^+μ^-$ decay mode we

Serdar Kuyucak, Andrew E. Stuchbery

Magnetic moment measurements in odd nuclei directly probe the distribution of fermion states and hence provide one of the most critical tests for multi-$j$ supersymmetries in collective nuclei. Due to complexity of calculations and lack of data, such tests have not been performed in the past. Using the Mathematica software, we derive analytic expressions for

T. Mefford, R. H. Landau

The angular momentum (partial wave) reduction of the Lippmann--Schwinger equation describing the interaction of two spin 1/2 particles is extended to the case in which the spin singlet and triplet states are coupled. A straight forward method for obtaining the angular momentum decomposition of the general potential is indicated. The derived formalism is need

P. Berglund

It is observed that a large class of $(2,2)$ string vacua with $n>5$ superfields can be rewritten as Landau_Ginzburg orbifolds with discrete torsion and $n=5$. The naive geometric interpretation (if one exists) would be that of a complex 3-fold, not necessarily Kähler but still with vanishing first Chern class.

Ted Jacobson

A derivation of the Hawking effect is given which avoids reference to field modes above some cutoff frequency $ω_c\gg M^{-1}$ in the free-fall frame of the black hole. To avoid reference to arbitrarily high frequencies, it is necessary to impose a boundary condition on the quantum field in a timelike region near the horizon, rather than on a (spacelike) Cauc

S. Mignemi

The spherical symmetric dyonic black hole solutions of the effective action of heterotic string are studied perturbatively up to second order in the inverse string tension. An expression for the temperature in term of the mass and the electric and magnetic charge of the black hole is derived and it is shown that its behaviour is qualitatively different in th

Krishna Rajagopal, Frank Wilczek

To model the dynamics of the chiral order parameter in a far from equilibrium phase transition, we consider quenching in the O(4) linear sigma model. We argue, and present numerical evidence, that in the period immediately following the quench long wavelength modes of the pion field are amplified. This results in large regions of coherent pion oscillations,

Marco A. Diaz

The calculation of the one-loop induced decay rate b -> s γis improved by including radiative corrections to the charged Higgs mass and to the charged-Higgs-fermion-fermion vertex. It is shown how the radiative corrections modify the excluded zone in the \tanβ-m_A plane, imposed by the non-observation of this decay. In particular, a light CP-odd Higgs at lar

Marco A. Diaz

One-loop radiative corrections to the charged Higgs coupling to two fermions and to the charged Higgs fermionic decay are studied. A renormalization scheme is proposed including the definition of the parameter $\tanβ$ through the coupling of the CP-odd Higgs boson to a charged lepton pair. Loops including top and bottom quarks and squarks are considered usin

Craig D. Roberts

A representative but not exhaustive review of the Schwinger-Dyson equation (SDE) approach to the nonperturbative study of QCD is presented. The main focus is the SDE for the quark self energy but studies of the gluon propagator and quark-gluon vertex are also discussed insofar as they are important to the quark SDE. The scope of this article is the applicati

Heath Pois, Thomas J. Weiler, Tzu Chiang Yuan

The rare decay modes Higgs $\rightarrow$ four light fermions, and Higgs $\rightarrow$ single top-quark + three light fermions for $m_t<M_H<2m_t$, are presented, and phenomenologically interpreted. The angular correlation between fermion planes is presented as a test of the spin and intrinsic parity of the Higgs particle. In Higgs decay to single top, two tre

P V Landshoff, A Rebhan

In the usual real-time finite-temperature gauge theory both the physical and the unphysical degrees of freedom are thermalised. We discuss the alternative approach where only the physical transverse components of the gauge field have bare thermal propagators, whereas the unphysical degrees of freedom are not heated. We show how pinch singularities are avoide

UKQCD Collaboration

We present an investigation of gauge-invariant smearing for Wilson fermions in quenched lattice QCD on a $24^3 \times 48$ lattice at $β= 6.2$. We demonstrate a smearing algorithm that allows a substantial improvement in the determination of the baryon spectrum obtained using propagators smeared at both source and sink, at only a small computational cost. We

E. F. Shender, V. B. Cherepanov, P. C. W. Holdsworth, A. J. Berlinsky

It is shown that site disorder induces noncoplanar states, competing with the thermal selection of coplanar states, in the nearest neighbor, classical kagome Heisenberg antiferromagnet (AFM). For weak disorder, it is found that the ground state energy is the sum of energies of separately satisfied triangles of spins. This implies that disorder does not induc

David G. Ebin, SUNY at Stony Brook, NY 11794-3651

We prove that the initial-value problem for the motion of a certain type of elastic body has a solution for all time if the initial data are sufficiently small. The body must fill all of three space, obey a ``neo-Hookean&#39;&#39; stress-strain law, and be incompressible. The proof takes advantage of the delayed singularity formation which occurs for solutio

Yao-Zhong Zhang, Mark D. Gould

Let $U_q(\hat{\cal G})$ denote the quantized affine Lie algebra and $U_q({\cal G}^{(1)})$ the quantized {\em nontwisted} affine Lie algebra. Let ${\cal O}_{\rm fin}$ be the category defined in section 3. We show that when the deformation parameter $q$ is not a root of unit all integrable representations of $U_q(\hat{\cal G})$ in the category ${\cal O}_{\rm f

Yao-Zhong Zhang, Mark D. Gould

Explicit formulas of the universal $R$-matrix are given for all quantized nontwisted rank 3 affine Lie algebras $U_q(A_2^{(1)})\,,~U_q(C_2^{(1)})$ and $U_q(G_2^{(1)})$.

Lev Rozansky

We calculate a large $k$ asymptotic expansion of the exact surgery formula for Witten&#39;s $SU(2)$ invariant of Seifert manifolds. The contributions of all flat connections are identified. An agreement with the 1-loop formula is checked. A contribution of the irreducible connections appears to contain only a finite number of terms in the asymptotic series.

R. Barbieri, G. F. Giudice

The inclusive radiative $B$-decay is a sensitive probe of new physics, especially if related to the virtual exchange of a charged Higgs boson. Supersymmetric models provide a particularly interesting example. In the limit of exact supersymmetry, BR($b \to sγ$)~=~0, due to the vanishing of any magnetic-moment transition operator. We illustrate the impact of t

Isidore Hauser, Frederick J. Ernst

A program is outlined concerning the set of all solutions of the hyperbolic Ernst equation on a two-dimensional manifold whose underlying topological space is the same as the domain of all Ernst potentials for colliding plane gravitational wave pairs. The aim of the program is to construct and apply a non-trivial extension of the group of Kinnersley-Chitre t

A. Marshakov

A review of the appearence of integrable structures in the matrix model description of $2d$-gravity is presented. Most of ideas are demonstrated at the technically simple but ideologically important examples. Matrix models are considered as a sort of &#34;effective&#34; description of continuum $2d$ field theory formulation. The main physical role in such de

S. Kharchev, A. Marshakov

We study the integral representation for the exact solution to nonperturbative $c le 1$ string theory. A generic solution is determined by two functions $W(x)$ and $Q(x)$ which behaive at infinity like $x^p$ and $x^q$ respectively. The integral model for arbitrary $(p,q)$ models is derived which explicitely demonstrates $p-q$ duality of minimal models couple

Conrad J. Burden, Craig D. Roberts

In the quenched approximation, the gauge covariance properties of three vertex Ans\"{a}tze in the Schwinger-Dyson equation for the fermion self energy are analysed in three- and four- dimensional quantum electrodynamics. Based on the Cornwall-Jackiw-Tomboulis effective action, it is inferred that the spectral representation used for the vertex in the gauge t

Yves Leroyer

We define a block observable for the $q$-state Potts model which exhibits an intermittent behaviour at the critical point. We express the intermittency indices of the normalised moments in terms of the magnetic critical exponent $β/ν$ of the model. We confirm this relation by a numerical similation of the $q=2$ (Ising) and $q=3$ two-dimensional Potts model.

Kenichiro Aoki, Eric D&#39;Hoker

We generalize the Lax pair and Bäcklund transformations for Liouville and Toda field theories as well as their supersymmetric generalizations, to the case of arbitrary Riemann surfaces. We make use of the fact that Toda field theory arises naturally and geometrically in a restriction of so called $W$--geometry to ordinary Riemannian geometry. This derivation

K. S. Babu, Q. Shafi

It was recently shown by the authors that the Fritzsch ansatz for the quark mass matrices prescribed at the supersymmetric grand unified scale is compatible with a moderately heavy top quark ($m_t \simeq 120-150~GeV$). Here we extend the ansatz to incorporate the charged leptons and the neutrinos. It is found that the $ν_e-ν_μ$ mixing angle is small and cons

M. Olechowski, S. Pokorski

A new approach is proposed to phenomenological study of a generic unified supergravity model, which reduces to the minimal supersymmetric standard model. The model is effectively parametrized in terms of five low energy observables. In consequence, it is easy to investigate systematically the parameter space of the model, allowed by the requirement of radiat

J. Ellis, D. Nanopoulos, D. Ross

We discuss systematically the consistency of light gluinos with data on perturbative QCD from deep inelastic scattering, quarkonia, jets at LEP, and the total hadronic cross-section in ${e^+ e^-}$ annihilation on the $Z$ peak and elsewhere. We demonstrate that, in addition to the well-known increase in the value of $α_s(m_Z)$ inferred from lower-energy data

S. Choi, T. Hatsuda, Y. Koike, Su H. Lee

We analyse the recent precision measurements of the lepton-hadron deep inelastic scattering at CERN and SLAC to extract model independent constraints among the nucleon matrix elements of the twist-4 operators. We also study a parameterization of these matrix elements and point out the possibility that the matrix elements of the quark-gluon mixed operator has

U. Zückert, R. Alkofer, H. Reinhardt, H. Weigel

The self-consistent chiral soliton of the Nambu--Jona-Lasinio model including the $ω,ρ$ and $a_1$ (axial-) vector meson fields besides the chiral angle is investigated. The resulting energy spectrum of the one particle Dirac Hamiltonian is strongly distorted leading to a polarized Dirac sea which carries the complete baryon number. This supports Witten&#39;s

Howard D. Trottier, R. M. Woloshyn

Flux-tubes in different representations of SU(2) and U(1) lattice gauge theories in three dimensions are measured. Wilson loops generate heavy ``quark-antiquark&#39;&#39; pairs in fundamental ($j=1/2$), adjoint ($j=1$), and quartet ($j=3/2$) representations of SU(2). The first direct lattice measurements of the flux-tube cross-section ${\cal A}_j$ as a funct

Sami Mitra, A. H. MacDonald

We have evaluated the angular-momentum distribution functions for finite numbers of electrons in Laughlin states. For very small numbers of electrons the angular-momentum state occupation numbers have been evaluated exactly while for larger numbers of electrons they have been obtained from Monte-Carlo estimates of the one-particle density matrix. An exact re

Didier POILBLANC

Clusters of the two-dimensionnal t--J model with 2 holes and up to 26 sites are diagonalized using a Lanczos algorithm. The behaviour of the binding energy with system size suggests the existence of a finite critical value of J above which binding occurs in the bulk. Only the d-wave pair field operator acting on the Heisenberg GS has a finite overlap with th

V. Charmandaris, P. N. Appleton, A. P. Marston

We present images of the peculiar galaxy Arp~10 which reveal two rings of concurrent star formation. Apart from a bright ring visible on early photographs of the system, an even brighter inner ring of \ion{H}{2} regions is found within the nuclear bulge of the galaxy. A very faint ring-arc of \ion{H}{2} regions is also seen associated with a third outer ring

Michael S. Chanowitz

The trace anomaly term in the low energy chiral Lagrangian is established by deriving a low energy theorem for $γγ\rightarrow π^0π^0$ scattering. It contributes to $σ(γγ\rightarrow π^0π^0)$ in the same order as the previously computed pion loop contribution. The coherent sum of the two contributions explains the shape of the measured cross section, while the

J. M. Daul, V. Kazakov, I. Kostov

The correspondence claimed by M. Douglas, between the multicritical regimes of the two-matrix model and 2D gravity coupled to (p,q) rational matter field, is worked out explicitly. We found the minimal (p,q) multicritical potentials U(X) and V(Y) which are polynomials of degree p and q, correspondingly. The loop averages W(X) and \tilde W(Y) are shown to sat

Paul Hoyer

\noindent The well-known exact solution of the massless Schwinger model can be simply obtained by perturbing around a vacuum without the Dirac sea of filled negative energy states. The unusual vacuum structure changes the sign of the $iε$ prescription at the negative energy pole of the free fermion propagator. Consequently, all convergent fermion loop integr

Saburo Higuchi, Chigak Itoi, Norisuke Sakai

The validity of the renormalization group approach for large $N$ is clarified by using the vector model as an example. An exact difference equation is obtained which relates free energies for neighboring values of $N$. The reparametrization freedom in field space provides infinitely many identities which reduce the infinite dimensional coupling constant spac

George Bathas, W. M. Kloet

Results for d$σ$/d$Ω$ and $A_N$ in the reaction $\bar{p}p \rightarrow π^- π^+$ are predicted by a simple quark model. They are compared to recent experimental data from LEAR, as well as to previous predictions from nucleon-exchange models. At low energy the quark model does better than the nucleon-exchange models, but the overall comparison to experiment rem

E. Moya de Guerra, L. Zamick

Within the unified model of Bohr and Mottelson we derive the following linear energy weighted sum rule for low energy orbital 1$^+$ excitations in even-even deformed nuclei $$S_{\rm LE}^{\rm lew} (M_1^{\rm orb}) \cong (6/5) ε(B(E2; 0^+_1 \rightarrow 2_1^+ K=0)/Z e^2<r^2>^2) μ^2_N$$ with B(E2) the E2 strength for the transition from the ground state to the fi

S. P. Tsarev

Remarkable parallelism between the theory of integrable systems of first-order quasilinear PDE and some old results in projective and affine differential geometry of conjugate nets, Laplace equations, their Bianchi-Baecklund transformations is exposed. These results were recently applied by I.M.Krichever and B.A.Dubrovin to prove integrability of some models

Tatsuo Kobayashi

We study a deformed $su(m|n)$ algebra on a quantum superspace. Some interesting aspects of the deformed algebra are shown. As an application of the deformed algebra we construct a deformed superconformal algebra. {}From the deformed $su(1|4)$ algebra, we derive deformed Lorentz, translation of Minkowski space, $iso(2,2)$ and its supersymmetric algebras as cl

Per Elmfors, Kari Enqvist, Iiro Vilja

The effective action is computed for the \lphi--theory at finite temperature for small perturbations about a constant background field, using a generalized tadpole method. We find the complete effective action, including the real and imaginary parts, to all orders in derivatives and to order ${\cal O}(λ^2)$. We demonstrate that the high $T$ approximation, wh

D. Atwood G. Eilam A. Soni

We show that the transverse polarization asymmetry of the $τ$-lepton in the decay $t\rightarrow b τν$ is extremely sensitive to CP violating phases arising from the charged Higgs exchange in the Weinberg model of CP non-conservation. Qualitatively, the polarization asymmetries are enhanced over rate or energy asymmetries by a factor of $\approx {m_t\over m_τ

Suraj N. Gupta, James M. Johnson, Wayne W. Repko

We examine the scattering of longitudinal $W$, $Z$ and Higgs bosons in the Standard Model using the equivalent Goldstone-boson Lagrangian. Our calculations include the full one-loop scattering matrix between the states $W^+_LW^-_L$, $Z_LZ_L$ and $HH$ with no restrictions on the relative sizes of $M_H$ and $\sqrt{s}$. In addition to deriving the perturbative

A. D. Martin, R. G. Roberts, W. J. Stirling

We study the possible flavour asymmetry, $\bar{u} \neq \bar{d}$, of the light quark sea distributions of the proton. We discuss the information that is at present available from data on deep-inelastic lepton-nucleon scattering and from Drell-Yan production on various nuclear targets. We show that the ratio of dilepton yields on hydrogen and deuterium targets

B. D. Keister

Light-front current matrix elements for elastic scattering from hadrons with spin~1 or greater must satisfy a nontrivial constraint associated with the requirement of rotational covariance for the current operator. Using a model $ρ$ meson as a prototype for hadronic quark models, this constraint and its implications are studied at both low and high momentum

S. Kanemura, T. Kubota, E. Takasugi

Upper bounds for neutral as well as charged Higgs boson masses in a two-doublet model are obtained on the basis of tree unitarity conditions à la Lee, Quigg and Thacker. A wide variety of scattering processes are considered so extensively that our bounds are more restrictive than those obtained previously for neutral Higgs bosons and are also of a new kind f

Henrik Bruus, Karsten Flensberg, Henrik Smith

We use a Boltzmann equation to determine the magnetoconductivity of quantum wires. The presence of a confining potential in addition to the magnetic field removes the degeneracy of the Landau levels and allows one to associate a group velocity with each single-particle state. The distribution function describing the occupation of these single-particle states

S. Carlip

The set of degenerate ground states of an arbitrary nonabelian topologically massive gauge theory is shown to be in one-to-one correspondence with the Hilbert space of the associated pure Chern-Simons theory. (Paper is being withdrawn: original conclusion is incorrect for the nonabelian case. For a correct treatment, see M. Asorey, S. Carlip, and F. Falceto,

Raiko P. Zaikov

The present paper is revised copy of hep-th/9303087 in which higher spin extensions of the nonabelian gauge symmetries for the classical WZNW model are considered. Both linear and nonlinear realizations of the extended affine Kac-Moody algebra are obtained. A characteristic property of the WZNW model is that it admits a higher spin linear realization of the

G. Krein, M. Nielsen, R. D. Puff, L. Wilets

Vertex corrections are taken into account in the Schwinger-Dyson equation for the nucleon propagator in a relativistic field theory of fermions and mesons. The usual Hartree-Fock approximation for the nucleon propagator is known to produce the appearance of complex (ghost) poles which violate basic theorems of quantum field theory. In a theory with vector me

Saharon Shelah

The feeling that those two forcing notions-Cohen and Random-(equivalently the corresponding Boolean algebras Borel(R)/(meager sets), Borel(R)/(null sets)) are special, was probably old and widespread. A reasonable interpretation is to show them unique, or ``minimal&#39;&#39; or at least characteristic in a family of ``nice forcing&#39;&#39; like Borel. We sh

Ryszard Frankiewicz, Saharon Shelah, Pawel Zbierski

It is proved that -- consistently -- there can be no ccc closed P-sets in the remainder space omega^* .

H. Nishino

We show that $~N=1$~ {\it supersymmetric} Kadomtsev-Petviashvili (SKP) equations can be embedded into recently formulated $~N=1$~ self-dual {\it supersymmetric} Yang-Mills theories after appropriate dimensional reduction and truncation, which yield three-dimensional supersymmetric Chern-Simons theories. Based on this result, we also give conjectural \hbox{$N

J. Gomis, J. Herrero, K. Kamimura, J. Roca

A relation between an $Sp(2M)$ gauge particle model and the zero-curvature condition in a two-dimensional gauge theory is presented. For the $Sp(4)$ case we construct finite \W-transformations.

Karyn M. Apfeldorf, Joaquim Gomis

We consider a one-dimensional Osp($N|2M$) pseudoparticle mechanical model which may be written as a phase space gauge theory. We show how the pseudoparticle model naturally encodes and explains the two-dimensional zero curvature approach to finding extended conformal symmetries. We describe a procedure of partial gauge fixing of these theories which leads ge

Niclas Engberg, Bengt E. W. Nilsson

Using operator sewing techniques we construct the Reggeon vertex involving four external ${\bf Z}_3$-twisted complex fermionic fields. Generalizing a procedure recently applied to the ordinary Ramond four-vertex, we deduce the closed form of the ${\bf Z}_3$ vertex by demanding it to reproduce the results obtained by sewing.

M. C. B. Abdalla, F. P. Devecchi, E. Abdalla

We discuss the Dirac quantization of two dimensional gravity with bosonic matter fields. After defining the extended Hamiltonian it is possible to fix the gauge completely. The commutators can all be obtained in closed form; nevertheless, the results are not particularly simple.

S. Kalyana Rama, Siddhartha Sen

The values of the Witten invariants, $I_W$, of the lens space $L(p, 1)$ for SU(2) at level $k$ are obtained for arbitrary $p$. A duality relation for $I_W$ when $p$ and $k$ are interchanged, valid for asymptotic $k$, is observed. A method for calculating $I_W$ for any group $G$ is described. It is found that $I_W$ for $Z_m$, even for $m = 2$, distinguishes 3

Haruhiko Terao, Kiyonori Yamada

We modify the $SL(2,{\bf R})/U(1)$ WZW theory, which was shown to describe strings in a 2D black hole, to be invariant under chiral $U(1)$ gauge symmetry by introducing a Steukelberg field. We impose several interesting gauge conditions for the chiral $U(1)$ symmetry. In a paticular gauge the theory is found to be reduced to the Liouville theory coupled to t

Taejin Lee, Phillial Oh

We propose a classical model for the non-Abelian Chern-Simons theory coupled to $N$ point-like sources and quantize the system using the BRST technique. The resulting quantum mechanics provides a unified framework for fractional spin, braid statistics and Knizhnik-Zamolodchikov equation.

Eric Braaten

The solution of the plasmon problem and the subsequent development of an effective field theory approach to ultrarelativistic plasmas are reviewed. The effective lagrangians that summarize collective effects in ultrarelativistic quark-gluon and electron-photon plasmas are presented. A generalization that describes an electromagnetic plasma at all temperature

Urs M. Heller

A brief review of the role of the Higgs mechanism and the ensuing Higgs particle in the Minimal Standard Model is given. Then the property of triviality of the scalar sector in the Minimal Standard Model and the upper bound on the Higgs mass that follows is discussed. It is emphasized that the bound is obtained by limiting cutoff effects on physical processe

Pankaj Jain, John P. Ralston

We introduce a data analysis procedure for color transparency experiments which is considerably less model dependent than the transparency ratio method. The new method is based on fitting the shape of the A dependence of the nuclear cross section at fixed momentum transfer to determine the effective attenuation cross section for hadrons propagating through t

M. E. Flatte&#39;, S. Quinlan, D. J. Scalapino

The phase variation of the superconducting gap over the (normal) Fermi surface of the high-temperature superconductors remains a significant unresolved question. Is the phase of the gap constant, does it change sign, or is it perhaps complex? A detailed answer to this question would provide important constraints on various pairing mechanisms. Here we propose

G. Giuricin, F. Mardirossian, M. Mezzetti, P. Monaco

Using a variety of parameters of local galaxy density, we have examined the effects of the environmental density on the presence of bar structures in spiral galaxies of various morphological types. For an extensive sample of nearby galaxies, listed in the ``Nearby Galaxies Catalogue&#39;&#39; (Tully, 1988a), we have found that the spirals characterized by a

M. Consoli, P. M. Stevenson

We argue that massless (lambda Phi^4)_4 is &#34;trivial&#34; without being entirely trivial. It has a non-trivial effective potential which leads to spontaneous symmetry breaking, but the particle excitations above the broken vacuum are non-interacting. The key to this picture is the realization that the constant background field (the mode with zero 4-moment

Masayasu Harada, Taichiro Kugo, Koichi Yamawaki

We prove to all orders of the loop expansion the low energy theorems of hidden local symmetries in four-dimensional nonlinear sigma models based on the coset space $G/H$, with $G$ and $H$ being arbitrary compact groups. Although the models are non-renormalizable, the proof is done in an analogous manner to the renormalization proof of gauge theories and two-

David Cai, A. R. Bishop, Niels Grønbech-Jensen

A new 1-D discrete nonlinear Schrödinger (NLS) Hamiltonian is introduced which includes the integrable Ablowitz-Ladik system as a limit. The symmetry properties of the system are studied. The relationship between intrinsic localized states and the soliton of the Ablowitz-Ladik NLS is discussed. It is pointed out that a staggered localized state can be viewed

S. A. Gurvitz, A. S. Rinat

We study the non-relativistic response of a &#39;diquark&#39; bound by confining forces, for which perturbation theory in the interaction fails. As non-perturbative alternatives we consider the Gersch-Rodriguez-Smith theory and a summation method. We show that, contrary to the case of singular repulsive forces, the GRS theory can generally be applied to conf

Yu. Makeenko

I review recent works on the problem of inducing large-N QCD by matrix fields. In the first part of the talk I describe the matrix models which induce large-N QCD and present the results of studies of their phase structure by the standard lattice technology (in particular, by the mean field method). The second part is devoted to the exact solution of these m

Didier Caenepeel, Richard MacKenzie

We examine an approach to justifying the mean field approximation for the anyon gas, using the scattering of anyons. Parity violation permits a nonzero average scattering angle, from which one can extract a mean radius of curvature for anyons. If this is larger than the interparticle separation, one expects that the graininess of the statistical magnetic fie

Masayasu Harada, Taichiro Kugo, Koichi Yamawaki

Based on the Ward-Takahashi identity for the BRS symmetry, we prove to all orders of the loop expansion the low energy theorem of hidden local symmetry for the vector mesons (KSRF (I) relation) in the $U(N)_{\rm L}$ $\times$ $U(N)_{\rm R}$ / $U(N)_{\rm V}$ nonlinear chiral Lagrangian.

James Botts, Jorge G. Morfin, Joseph F. Owens, Jianwei Qiu

This paper describes salient features of new sets of parton distributions obtained by the CTEQ Collaboration based on a comprehensive QCD global analysis of all available data. The accuracy of the new data on deep inelastic scattering structure functions obtained by the very high statistics NMC and CCFR experiments provides unprecedented sensitivity to the f

Tarik Celik, Ulrich H. E. Hansmann, Bernd Berg

We performed numerical simulations of 2D and 3D Edwards-Anderson spin glass models by using the recently developed multicanonical ensemble. Our ergodicity times increase with the lattice size approximately as $V^3$. The energy, entropy and other physical quantities are easily calculable at all temperatures from a single simulation. Their finite size scalings

Silas R. Beane, Charles B. Chiu

We consider the scattering of Goldstone bosons in the range of intermediate energies, and in particular focus our attention on the scattering of pions in the $ρ$-resonance region. The chiral perturbation series is obtained to order $E^4$ from a chiral $SU(2)\times SU(2)$ invariant effective Lagrangian. At order $E^4$, we isolate the low-energy manifestation

Kim Griest

Review talk presented at the Texas/PASCOS Symposium, Berkeley, CA, Dec 1992. We review the status of experiments and ideas relevant for the detection of the dark matter which is suspected to be the dominant constituent of the Universe. Great progress is being made and the chances are non-negligible that one of the many currently in-progress experiments will

Mohammad Katoot, Ulrich H. E. Hansmann, Tarik Celik

We studied the performance of the multicanonical algorithm by simulating the van Hemmen spin glass model and reproduced the exact results for this mean field model. Physical quantities such as energy density, specific heat, susceptibility and order parameters are evaluated at all temperatures.

Ulrich H. E. Hansmann, Yuko Okamoto

We test the effectiveness of the multicanonical algorithm for the tertiary structure prediction of peptides and proteins. As a simple example we study Met-enkephalin. The lowest-energy conformation obtained agrees with that determined by other methods such as Monte Carlo simulated annealing. But unlike to simulated annealing the relationship to the canonical

G. Papadopoulos, B. Spence

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Michael Luke, Martin J. Savage

We examine the decays $t\rightarrow cγ$ and $c Z^0$ in the Standard Model with an extra scalar doublet and no discrete symmetry preventing tree-level flavour changing neutral currents. The Yukawa couplings of the new scalars are assumed to be proportional to fermion masses, evading bounds on FCNC&#39;s from the light quark sector. These rare top decays may b

M. A. Clayton, L. Demopoulos, J. W. Moffat

Nonlocal regularization of QED is shown to possess an axial anomaly of the same form as other regularization schemes. The Noether current is explicitly constructed and the symmetries are shown to be violated, whereas the identities constructed when one properly considers the contribution from the path integral measure are respected. We also discuss the barri

T. Bhattacharya, R. Lacaze, A. Morel

We present a large $q$ expansion of the 2d $q$-states Potts model free energies up to order 9 in $1/\sqrt{q}$. Its analysis leads us to an ansatz which, in the first-order region, incorporates properties inferred from the known critical regime at $q=4$, and predicts, for $q>4$, the $n^{\rm th}$ energy cumulant scales as the power $(3 n /2-2)$ of the correlat

Ramzi R. Khuri

String configurations with nonzero winding number describe soliton string states. We compute the Veneziano amplitude for the scattering of arbitrary winding states and show that in the large radius limit the strings always scatter trivially and with no change in the individual winding numbers of the strings. In this limit, then, these states scatter as true

H. Lew

The cosmological and astrophysical implications of a shadow matter model which could also have interesting experimental consequences are examined. The model has identical microphysics for both the ordinary and shadow worlds but requires a macroscopic asymmetry from nucleosynthesis constraints. It is proposed that this macroscopic asymmetry can be generated a

W. Buchmüller, Z. Fodor T. Helbig, D. Walliser

We present a detailed analysis of the phase transition in the standard model at finite temperature. Using an improved perturbation theory, where plasma masses are determined from a set of one-loop gap equations, we evaluate the effective potential $V_{eff}(φ,T)$ in next-to-leading order, i.e., including terms cubic in the gauge coupling $g$, the scalar self-

Z. Lalak, S. Thomas

We consider the evolution of the probability distribution $\pp (χ,\chib, \t)$, associated with an inhomogeneous light scalar field $χ$ in the Robertson-Walker Universe, where the inhomogeneities are produced by quantum fluctuations during an earlier inflationary epoch. For a specific choice of scalar potential which occurs in models of so called late-time ph

Don N. Page

Testable conditional probabilities appear to be restricted to single hypersurfaces (marvelous moments) and depend only on stationary observables. Observable evolution, such as a change of entropy, should be expressed as a dependence upon clock time, not upon inaccessible coordinate time.