December 1994 arXiv papers — page 3

H. Arisue

We calculate the low-temperature series of the free energy in absolute-value solid-on-solid (ASOS) model to order $u^{23}$ using finite-lattice method. The property of the obtained series and the behavior of their Padé approximants confirms us that the roughening transition in ASOS model is of Kosterlitz-Thouless type.

John Sloan

The status of b-bbar and c-cbar calculations, numerical and analytic, are reviewed. The extraction of alpha_s and quark masses from spectrum calculations is discussed. The NRQCD and Improved Heavy Wilson formulations of heavy quarks are compared, and recent calculations using a Heavy Staggered formulation are discussed.

Steven R. Brandt, Edward Seidel

We have developed a numerical code to study the evolution of distorted, rotating black holes. This code is used to evolve a new family of black hole initial data sets corresponding to distorted ``Kerr'' holes with a wide range of rotation parameters, and distorted Schwarzschild black holes with odd-parity radiation. Rotating black holes with rotation

Steven R. Brandt, Edward Seidel

We have developed a new numerical code to study the evolution of distorted, rotating black holes. We discuss the numerical methods and gauge conditions we developed to evolve such spacetimes. The code has been put through a series of tests, and we report on (a) results of comparisons with codes designed to evolve non-rotating holes, (b) evolution of Kerr spa

Carles Bona, Joan Masso, Joan Stela

Spherically symmetric (1D) black-hole spacetimes are considered as a test for numerical relativity. A finite difference code, based in the hyperbolic structure of Einstein's equations with the harmonic slicing condition is presented. Significant errors in the mass function are shown to arise from the steep gradient zone behind the black hole horizon, whi

Peter Anninos, Greg Daues, Joan Masso, Edward Seidel

It was recently shown that spacetime singularities in numerical relativity could be avoided by excising a region inside the apparent horizon in numerical evolutions. In this paper we report on the details of the implementation of this scheme. The scheme is based on using (1)~a horizon locking coordinate which locks the coordinate system to the geometry, and

Joseph Libson, Joan Masso, Edward Seidel, Wai-Mo Suen

This is the first paper in a series on event horizons in numerical relativity. In this paper we present methods for obtaining the location of an event horizon in a numerically generated spacetime. The location of an event horizon is determined based on two key ideas: (1) integrating backward in time, and (2) integrating the whole horizon surface. The accurac

S. V. Kravchenko, Whitney E. Mason, G. E. Bowker, J. E. Furneaux

We have studied the temperature dependence of resistivity, $ρ$, for a two-dimensional electron system in silicon at low electron densities, $n_s\sim10^{11}$ cm$^{-2}$, near the metal/insulator transition. The resistivity was empirically found to scale with a single parameter, $T_0$, which approaches zero at some critical electron density, $n_c$, and increase

H. J. Mo, S. D. M. White

We develop a simple analytic model for the gravitational clustering of dark haloes. The statistical properties of dark haloes are determined from the initial density field (assumed to be Gaussian) through an extension of the Press-Schechter formalism. Gravitational clustering is treated by a spherical model which describes the concentration of dark haloes in

Roland J. Egger, Bernd Aschenbach, MPE Garching, GERMANY

A soft X-ray shadow has been discovered on the periphery of the Loop I supershell in the ROSAT All Sky Survey. The distance, size, geometry and spectral data indicate that it is cast by an annular volume of dense neutral matter which has formed in the collision of the Loop I superbubble and the Local Hot Bubble. This is the first observation of the interacti

Joakim Hallin, Per Liljenberg

We solve the time evolution of the density matrix both for fermions and bosons in the presence of a homogeneous but time dependent external electric field. The number of particles produced by the external field, as well as their distribution in momentum space is found for finite times. Furthermore, we calculate the probability of finding a given number of pa

H. J. Schulz

A model of two interacting one--dimensional fermion systems (``Luttinger liquids'') coupled by single--particle hopping is investigated. Bosonization allows a number of exact statements to be made. In particular, for forward scattering only, the model contains two massless boson sectors and an Ising type critical sector. For general interactions, the

J. D. Hayward

The RST Model is given boundary term and Z-field so that it is well-posed and local. The Euclidean method is described for general theory and used to calculate the RST intrinsic entropy. The evolution of this entropy for the shockwave solutions is found and obeys a second law.

Martin U. Schmidt

To the spectral curves of smooth periodic solutions of the $n$-wave equation the points with infinite energy are added. The resulting spaces are considered as generalized Riemann surfcae. In general the genus is equal to infinity, nethertheless these Riemann surfaces are similar to compact Riemann surfaces. After proving a Riemann Roch Theorem we can carry o

G. Schrade, V. M. Akulin, W. P. Schleich, V. I. Man'ko

We investigate the general case of the photon distribution of a two-mode squeezed vacuum and show that the distribution of photons among the two modes depends on four parameters: two squeezing parameters, the relative phase between the two oscillators and their spatial orientation. The distribution of the total number of photons depends only on the two squee

Holger Ewen, Oleg Ogievetsky

We define quantum matrix groups GL(3) by their coaction on appropriate quantum planes and the requirement that the Poincare series coincides with the classical one. It is shown that this implies the existence of a Yang-Baxter operator. Exploiting stronger equations arising at degree four of the algebra, we classify all quantum matrix groups GL(3). We find 26

David Seibert

The observation of scaling relations in ultra-relativistic nuclear collisions would not by itself signal that the hot matter produced in these collisions has passed through a phase transition.

Rici Yu, Henry Krakauer

A complete mapping in the Brillouin zone of the structural instability associated with the ferroelectric phase transitions of KNbO$_3$ has been obtained by first-principles calculations using an LAPW linear response approach. The wavevector dependence of the instability reveals pronounced two-dimensional character, which corresponds to chains oriented along

Alberto Corso, Claudia Polini

In a previous paper we exhibited the somewhat surprising property that most direct links of prime ideals in Gorenstein rings are equimultiple ideals with reduction number $1$. This led to the construction of large families of Cohen--Macaulay Rees algebras. The first goal of this paper is to extend this result to arbitrary Cohen--Macaulay rings. The means of

Alexander Sukhov

We propose a reflection principle for holomorphic objects in ${\Bbb C}^n$. Our construction generalizes the classical principle of H.Lewy, S.Pinchuk and S.Webster.

Harold P. Boas

The bounded domains of holomorphy in~$\mathbf{C}^n$ whose Bergman kernel functions are zero-free form a nowhere dense subset (with respect to a variant of the Hausdorff distance) of all bounded domains of holomorphy.

Prem P. Srivastava

The scalar field is quantized in the discretized light-front framework following the {\em standard} Dirac procedure and its infinite volume limit taken. The background field and the nonzero mode variables do not commute for finite volume; they do so only in the continuum limit. A {\em non-local constraint} in the theory relating the two is shown to follow an

J. D. Kim

( We present complete solutions of $K$-matrix for the quantum Mikhailov-Shabat model. It has been known that there are three diagonal solutions with no free parameters, one being trivial identity solution, the others non-trivial. The most general solutions which we found consist of three families corresponding to each diagonal solutions. One family of soluti

Jose Gaite

We consider the relation between affine Toda field theories (ATFT) and Landau-Ginzburg Lagrangians as alternative descriptions of deformed 2d CFT. First, we show that the two concrete implementations of the deformation are consistent once quantum corrections to the Landau-Ginzburg Lagrangian are taken into account. Second, inspired by Gepner's fusion pot

E. G. Kalnins, V. B. Kuznetsov, Willard Miller,

In this work we generalise previous results connecting (rational) Gaudin magnet models and classical separation of variables. It is shown that the connection persists for the case of linear r-matrix algebra which corresponds to the trigonometric 4x4 r-matrix (of the XXZ type). We comment also on the corresponding problem for the elliptic (XYZ) r-matrix. A pr

Farid Benachenhou

This thesis is a review of black hole evaporation with emphasis on recent results obtained for two dimensional black holes. First, the geometry of the most general stationary black hole in four dimensions is described and some classical quantities are defined. Then, a derivation of the spectrum of the radiation emitted during the evaporation is presented. In

D. Nemeschansky, N. P. Warner

We describe, in some detail, a number of different Coulomb gas formulations of $N=2$ superconformal coset models. We also give the mappings between these formulations. The ultimate purpose of this is to show how the Landau-Ginzburg structure of these models can be used to extract the $W$-generators, and to show how the computation of the elliptic genus can b

A. Casher, V. Elkonin, Y. Shamir

Instanton effects in a family of completely massive Higgs models with N=1 supersymmetry are investigated. The models have $N_c=2$ and $N_f\ge 2$. In each model, we show that a certain gauge invariant correlation function depends in a non-trivial way on its coordinates, in spite of the fact that supersymmetry requires its constancy. This means that non-pertur

Daniel Kastler, Thomas Schucker

The relations among coupling constants and masses in the standard model à la Connes-Lott with general scalar product are computed in detail. We find a relation between the top and the Higgs masses. For $m_t=174\pm22\ GeV$ it yields $m_H=277\pm40\ GeV$. The Connes-Lott theory privileges the masses $m_t=160.4\ GeV$ and $m_H=251.8\ GeV$.

Kazuto Oshima

We study the $O(N)$ non-linear $σ$ model on three-dimensional manifolds of constant curvature by means of the large $N$ expansion at the critical point. We examine saddle point equations imposing anti-periodic boundary condition in time direction. In the case $S^1 \times S^2$ we find that a solution is inevitably unstable. We briefly refer to the case $S^1 \

Jens Schnittger

This review contains a summary of work by J.-L. Gervais and the author on the operator approach to 2d gravity. Special emphasis is placed on the construction of local observables -the Liouville exponentials and the Liouville field itself - and the underlying algebra of chiral vertex operators. The double quantum group structure arising from the presence of t

J. G. Koerner, J. Landgraf

We discuss the structure of current-induced bottom baryon to charm baryon transitions, and the structure of pion and photon transitions between heavy charm or bottom baryons in the Heavy Quark Symmetry limit as ${\scriptstyle m_Q\rightarrow \infty}$. Our discussion involves the ground state $s$-wave heavy baryons as well as the excited $p$-wave heavy baryon

Gregory Mahlon

We illustrate the use of recursion relations in the computation of certain one-loop helicity amplitudes containing an arbitrary number of gauge bosons. After a brief review of the recursion relations themselves, we discuss the resolution of the apparent conflict between the spinor helicity method used to solve the recursion relations and the dimensional regu

Lali Chatterjee, Cheuk-Yin Wong

In reactions with $q \bar q$ production or $q\bar q$ annihilation, initial- and final-state interactions give rise to large corrections to the lowest-order cross sections. We evaluate the correction factor first for low relative kinetic energies by studying the distortion of the relative wave function. We then follow the procedure of Schwinger to interpolate

S. Frixione, M. L. Mangano, P. Nason, G. Ridolfi

We compute total cross sections for charm and bottom photoproduction at HERA energies, and discuss the relevant theoretical uncertainties. In particular we discuss the problems arising from the small-$x$ region, the uncertainties in the gluon parton density, and the uncertainties in the hadronic component of the cross section. Total electroproduction cross s

François Gelis

The effect of the contribution of the vertical part of the real time path is studied completely in the case of two points functions. Indeed, this vertical part generally contributes in the calculation of a given graph. Moreover, this contribution is essential in order to have a consistent equilibrium theory: thanks to this contribution, the Green function ar

J. Lopez, D. Nanopoulos, X. Wang, A. Zichichi

We consider the production of supersymmetry neutralinos and charginos in $p\bar p$ collisions at the Tevatron, and their subsequent decay via hadronically quiet dileptons and trileptons. We perform our computations in the context of a variety of supergravity models, including generic four-parameter supergravity models, the minimal $SU(5)$ supergravity model,

Eugene Levin

The role of infrared and ultraviolet renormalons are discussed in context of leading log(1/x) approximation of perturbative QCD. We generalize the BFKL equation for the case of running coupling QCD constant and show that the uncertainties related to the contribution of infrared renormalons turn out to be smaller than the shadowing correction to the total cro

N. N. Nikolaev, G. Piller, B. G. Zakharov

We describe a light-cone wave function formalism for hadroproduction of heavy-flavors via gluon-gluon fusion. The developed approach is well suited to address coherence effects in heavy-quark production on nuclei at small $x_{2} \lsim 0.1\cdot A^{-1/3}$. Nuclear attenuation in hadroproduction of heavy-flavors is found to be similar to shadowing effects for h

Santiago Peris, Eduardo de Rafael

It is shown that the usual large-$N_c$ counting of the coupling constant $L_{7}$ of the ${\cal O}(p^4)$ low-energy chiral $SU(3)$ Lagrangian \cite{GL85} is in conflict with general properties of QCD in the large-$N_c$ limit. The solution of this conflict within the framework of a chiral $U(3)$ Lagrangian is explained.

R. Kobayashi, M. Konuma, S. Kumano, M. Miyama

We discuss numerical solution of Altarelli-Parisi equations in a Laguerre-polynomial method and in a brute-force method. In the Laguerre method, we get good accuracy by taking about twenty Laguerre polynomials in the flavor-nonsinglet case. Excellent evolution results are obtained in the singlet case by taking only ten Laguerre polynomials. The accuracy beco

Hsiang-nan Li

We examine the applicability of perturbative QCD to $B$ meson decays into $D$ mesons. We find that the perturbative QCD formalism, which includes Sudakov effects at intermediate energy scales, is applicable to the semi-leptonic decay $B\to D lν$, when the $D$ meson recoils fast. Following this conclusion, we analyze the two-body non-leptonic decays $B\to Dπ$

J. Fingberg

We examined the effect of a complete suppression of a lattice artifact, the negative plaquettes, on physical quantities, such as the critical temperature, the string tension, the topological charge, glueball masses, and their ratios.

Eric W. Hirschmann, Douglas M. Eardley

This paper studies gravitational collapse of a complex scalar field at the threshold for black hole formation, assuming that the collapse is spherically symmetric and continuously self-similar. A new solution of the coupled Einstein-scalar field equations is derived, after a small amount of numerical work with ordinary differential equations. The universal s

T. Damour

The confrontation between General Relativity and experimental results, notably binary pulsar data, is summarized and its significance discussed. The agreement between experiment and theory is numerically very impressive. However, some recent theoretical findings (existence of non-perturbative strong-field effects, natural cosmological attraction toward zero

T. Damour

The absence of gravitational radiation in Kinnersley's ``photon rocket'' solution of Einstein's equations is clarified by studying the mathematically well-defined problem of point-like photon rockets in Minkowski space (i.e. massive particles emitting null fluid anisotro\-pically and accelerating because of the recoil). We explicitly compute

Edward Seidel, Wai-Mo Suen

We showed that compact bosonic objects can be formed through a process we called gravitational cooling. A central issue in the subject of boson star is whether a classical field configuration, {\it e.g.,} one described by the Klein-Gordon equation, can collapse to form a compact star-like object, as there is apparently no dissipation in the Klein-Gordon equa

Carles Bona, Joan Stela, Joan Masso, Edward Seidel

Using the momentum constraint, the standard evolution system is written in a fully first order form. The class of first order invariant algebraic slicing conditions is considered. The full set of characteristic fields is explicitly given. Characteristic speeds associated to the gauge dependent eigenfields (gauge speeds) are related to light speed.

Joan Masso

I report on recent progress in the exciting field of Numerical Relativity, with special attention to black hole horizons.

Peter Anninos, Karen Camarda, Joan Masso, Edward Seidel

Numerical relativity is finally coming of age with the development of massively parallel computers. 3D problems, which were completely intractable several years ago due to limited computer power, can now be performed with grid sizes of about $200^3$. We report on several new codes developed for solving the full 3D Einstein equations, and present results of u

Joseph Libson, Joan Masso, Edward Seidel, Wai-Mo Suen

We report on an efficient method for locating the apparent horizon in numerically constructed dynamical 3D black hole spacetimes. Instead of solving the zero expansion partial differential equation, our method uses a minimization procedure. Converting the PDE problem to minimization eliminates the difficulty of imposing suitable boundary conditions for the P

Joan Masso, Edward Seidel, Paul Walker

We discuss the use of Adaptative Mesh Refinement (AMR) techniques in dynamical black hole spacetimes. We compare results between traditional fixed grid methods and a new AMR application for the 1-D Schwarzschild case.

Peter Anninos, David Bernstein, Steven Brandt, Joan Masso

We have developed a powerful and efficient method for locating the event horizon of a black hole spacetime, making possible the study of the dynamics of event horizons in numerical relativity. We describe the method and apply it to a colliding black hole spacetime.

Peter Anninos, Greg Daues, Joan Masso, Edward Seidel

Spacetime singularities in numerical relativity can be avoided by excising a region of the computational domain from inside the apparent horizon. We report on results of such a scheme that is based on using ({\it i}) a horizon locking coordinate which locks the coordinate system to the geometry, and ({\it ii}) a finite differencing scheme which respects the

Johannes Huebschmann

Let $G$ be a Lie group with a biinvariant metric, not necessarily positive definite. It is shown that a certain construction carried out in an earlier paper for the fundamental group of a closed surface may be extended to an arbitrary infinite orientation preserving cocompact planar discrete group of euclidean or non-euclidean motions $π$ and yields (i) a sy

C. ~B. ~Hanna, D. ~P. ~Arovas, K. ~Mullen, S. ~M. ~Girvin

We study the delocalization transition for spin-polarized and spin-degenerate non-interacting electrons in the lowest Landau level. We perform finite-size scaling calculations of the Thouless number, for varying amounts of potential and spin-orbit scattering. {}For spin-polarized electrons, we obtain a one-parameter scaling function for the Thouless number t

A. G. Aronov, E. Altshuler, A. D. Mirlin, P. Woelfle

We present a theory of magnetooscillations around the $ν=1/2$ Landau level filling factor based on a model with a fluctuating Chern--Simons field. The quasiclassical treatment of the problem is appropriate and leads to an unconventional $\exp\left[-(π/ω_cτ^*_{1/2})^4\right]$ behavior of the amplitude of oscillations. This result is in good qualitative agreem

G. Vignale

It is shown that the exchange-correlation part of the action functional $A_{xc}[ρ(\vec r,t)]$ in time-dependent density functional theory , where $ρ(\vec r,t)$ is the time-dependent density, is invariant under the transformation to an accelerated frame of reference $ρ(\vec r,t) \to ρ' (\vec r,t) = ρ(\vec r + \vec x (t),t)$, where $\vec x (t)$ is an arbit

Michel Droz, Pierre-Antoine Rey, Laurent Frachebourg, Jarosław Piasecki

Ballistic annihilation kinetics for a multi-velocity one-dimensional ideal gas is studied in the framework of an exact analytic approach. For an initial symmetric three-velocity distribution, the problem can be solved exactly and it is shown that different regimes exist depending on the initial fraction of particles at rest. Extension to the case of a n-velo

Francesco D. Di Tolla, Furio Ercolessi, Erio Tosatti

Surfaces which do not exhibit surface melting below the melting point (nonmelting surfaces) have been recently observed to sustain a very large amount of overheating. We present a theory which identifies a maximum overheating temperature, and relates it to other thermodynamical properties of the surface, in particular to geometrical properties more readily a

I. V. Krive, R. I. Shekhter, S. M. Girvin, M. Jonson

We calculate the magnetic moment (`persistent current') in a strongly correlated electron system --- a Wigner crystal --- in a one-dimensional ballistic ring. The flux and temperature dependence of the persistent current in a perfect ring is shown to be essentially the same as for a system of non-interacting electrons. In contrast, by incorporating into

F. Dalfovo, A. Lastri, L. Pricaupenko, S. Stringari

We present a novel density functional for liquid 4He, properly accounting for the static response function and the phonon-roton dispersion in the uniform liquid. The functional is used to study both structural and dynamical properties of superfluid helium in various geometries. The equilibrium properties of the free surface, droplets and films at zero temper

J. G. Skibo, C. D. Dermer, R. Ramaty, J. M. McKinley

We use a Monte Carlo simulation to calculate the spectra of mildly relativistic thermal plasmas in pair balance. We use the exact integral expression for the electron-positron thermal annihilation spectrum, and provide accurate expressions for the Gaunt factors of electron-ion, electron-electron, and electron-positron thermal bremsstrahlung in the transrelat

N. Benitez, E. Martinez-Gonzalez, J. I. Gonzalez-Serrano, L. Cayon

We have taken deep $R$-band images of fields around five radiogalaxies: 0956+47, 1217+36, 3C256, 3C324 and 3C294 with $1<z<2$ . 0956+47 is found to show a double nucleus. Our data on 1217+36 suggest the revision of its classification as a radiogalaxy. We found a statistically significant excess of bright ($19.5<R<22$) galaxies on scales of 2 arcmin around th

J. I. Katz

Observed intensities and inferred distances of soft gamma repeaters imply luminosities in excess of the nominal (electron-scattering opacity) Eddington limit by four to six orders of magnitude. I review the physical basis of this limit. Accretional luminosities may exceed it if energy is hydrodynamically coupled from accreting matter to closed field lines wh

Xiang-Ping Wu, Zugan Deng, Zhenlong Zou, Li-Zhi Fang

Astrophysical observations indicate that the ``Local Universe&#34; has a relatively lower matter density ($Ω_0$) than the predictions of the standard inflation cosmology and the large-scale motions of galaxies which provide a mean mass density to be very close to unity. In such a local underdense region the Hubble expansion may not be representative of the g

Steven Kleiman, Anders Thorup

We prove the results about mixed Buchsbaum--Rim multiplicities announced in (9.10)(ii) on p.224 of our recent paper [J.Alg.(1994)], including a general mixed-multiplicity formula. In addition, we identify these multiplicities as the coefficients of the ``leading form&#39;&#39; of the appropriate Buchsbaum-Rim polynomial in three variables, and we prove a pos

M. Bordag, A. A. Bytsenko

We calculate the one-loop corrections to the free energy and to the entropy for fields with arbitrary spins in the space $S^1\otimes H^N$. For conformally invariant fields by means of a conformal transformation of the metric the results are valid in Rindler space with $D=N+1$ dimensions. We use the zeta regularization technique which yields an ultraviolet fi

Andrew Gould

Microlensing searches toward the inner galaxy $(|l|,|b|\leq 22.\hskip-2pt&#39;5)$ have several major advantages. First, the event rate is strongly dominated by bulge-bulge lensing events where both the source and lens lie in the bulge. Second, these bulge-bulge events have very short time scales $t_e\sim 2\,$days and are therefore easily distinguished from t

M. Yu. Kalmykov, P. I. Pronin

We investigate the role of the torsion field at the quantum level in the affine-metric theory of gravity. One-loop counterterms are calculated in the theory with terms quadratic in the torsion field.

J. Lopez, D. Nanopoulos

We explore the postulates of string no-scale supergravity in the context of free-fermionic string models. The requirements of vanishing vacuum energy, flat directions of the scalar potential, and stable no-scale mechanism impose strong restrictions on possible string no-scale models, which must possess only two or three moduli, and a constrained massless spe

Jacek Dziarmaga

I derive a general formalism for finding kinetic terms of the effective Lagrangian for slowly moving Chern-Simons vortices. Deformations of fields linear in velocities are taken into account. From the equations they must satisfy I extract the kinetic term in the limit of coincident vortices. For vortices passing one over the other there is locally the right-

S. V. Semenov, V. V. Khruschev

The universality hypothesis for scalar confining potential between quark and antiquark with different flavours is confirmed within 0.05 level of relativity errors.

Georges BOUZERAR, Didier POILBLANC

Persistent currents of disordered multichannel mesoscopic rings of spinless interacting fermions threaded by a magnetic flux are calculated using exact diagonalizations and self-consistent Hartree-Fock methods. The validity of the Hartree-Fock approximation is controled by a direct comparison with the exact results on small $4\times4$ clusters. For sufficien

R. Chatterjee

We compute the exact partition function of the 2D Ising Model at critical temperature but with nonzero magnetic field at the boundary. The model describes a renormalization group flow between the free and fixed conformal boundary conditions in the space of boundary interactions. For this flow the universal ground state degeneracy $g$ and the full boundary st

Eun-jin Kim, Angela Olinto, Robert Rosner

We study the generation and evolution of density perturbations and peculiar velocities due to primordial magnetic fields. We assume that a random magnetic field was present before recombination and follow the field&#39;s effect on the baryon fluid starting at recombination. We find that magnetic fields generate growing density perturbations on length scales

Greg Anderson, Diego Castano

Superpartner masses cannot be arbitrarily heavy if supersymmetric extensions of the standard model explain the stability of the gauge hierarchy. This ancient and hallowed motivation for weak scale supersymmetry is often quoted, yet no reliable determination of this upper limit on superpartner masses exists. In this paper we compute upper bounds on superpartn

Dan Radu Grigore

We apply Mackey procedure of classifying projective systems of imprimitivity to a thorough study of the projective unitary irreducible representations of the Galilei group in 1+3 and 1+2 dimensions.

Pavel Etingof

We describe a generalization of Drinfeld&#39;s description of the center of a quantum group to the case of quantum affine algebras. We use the obtained central elements to construct the affine analogue of Macdonald&#39;s difference operators.

D. S. Koltun, T. C. Ferree

We extend the formulation of relativistic Coulomb sum rules to account for the average effects of nuclear binding on the initial and final states of ejected nucleons. Relativistic interactions are included by using a Dirac representation adapted from a vector-scalar field theory. The scalar field reduces the effective nucleon mass $M^*$ and increases the rel

David Goldberg

The tempered spectrum of the similitude groups of non-degenerate symplectic, hermitian, or split orthogonal forms defined over $p$\snug-adic groups of characteristic zero is studied. The components of representations induced from discrete series of proper parabolic subgroups are classified in terms of $R$\snug-groups. Multiplicity one is proved. The tempered

Paolo Rossi, Chung-I Tan

Principal chiral models on a d-1 dimensional simplex are introduced and studied analytically in the large $N$ limit. The $d = 0, 2, 4$ and $\infty$ models are explicitly solved. Relationship with standard lattice models and with few-matrix systems in the double scaling limit are discussed.

R. Floreanini, R. Percacci

We consider a scalar-metric gauge theory of gravity with independent metric, connection and dilaton. The role of the dilaton is to provide the scale of all masses, via its vacuum expectation value. In this theory, we study the renormalization group flow of the dilaton potential, taking into account threshold effects at the Planck scale. Due to the running of

Nathan Berkovits

It is proven that up to possible surface terms, the only non-vanishing momentum-dependent amplitudes for the self-dual N=2 string in $R^{2,2}$ are the tree-level two and three-point functions, and the only non-vanishing momentum-independent amplitudes are the one-loop partition function and the tree-level two and four-point functions. The calculations are pe

B. Linet

Motivated by the example of the superconducting cosmic string which can be a physical representation of a straight wire carrying a steady current, we derive in this case the explicit expressions of the induced vector potential, current density and magnetic field due to the vacuum polarization at the first order in the fine structure constant.

P. Di Francesco, C. Itzykson

We examine a few problems of enumerative geometry and present their solutions in the framework of deformed (quantum) cohomology rings.

Shogo Tanimura

We consider the $ U(1) $ sigma model in the two dimensional space-time which is a field-theoretical model possessing a nontrivial topology. It is pointed out that its topological structure is characterized by the zero-mode and the winding number. A new type of commutation relations is proposed to quantize the model respecting the topological nature. Hilbert

B. K. Chung, Soonkeon Nam, Q-Han Park, H. J. Shin

A new effective action for the high energy quark-quark scatterings is obtained by applying a scaling approximation to the QCD action. The propagators are shown to factorize into the transverse and the longitudinal parts so that the scattering amplitudes are given in terms of the products of two dimensional $S$-matrices. we show that our action provides a nat

Dinko Pocanic

Present status of the study of the low energy $\pi\pi$ interaction is reviewed, including the recent results on reactions $\pi N \to\pi\pi N$ near threshold. Current experimental values of s-wave $\pi\pi$ scattering lengths are compared with predictions of various theoretical models. Required experimental and theoretical improvements are discussed, in partic

W. T. Giele, E. W. N. Glover, David A. Kosower

We study the inclusive two jet triply differential cross section $d^3σ/dE_Tdη_1dη_2$ at Fermilab energies. Different $η_1$ and $η_2$ pseudorapidity regions are directly related to both the parton level matrix elements and the parton densities at leading order. We present the next-to-leading order [${\cal O}(α_s^3)$] corrections and show that the shape of the

Thomas Mannel, Gerhard Schuler

We discuss systems containing a heavy quark and a heavy antiquark in the infinite mass limit of QCD. Studying the limit of equal velocities for both heavy particles, we formulate an effective theory approach to heavy quarkonia-like systems. The method is well suited to processes in which the two heavy quarks annihilate, such as electromagnetic and strong dec

E. K. Sarkisyan, L. K. Gelovani, G. L. Gogiberidze, G. G. Taran

Results on dynamical fluctuations of charged particles in the pseudorapidity space of central C--Cu interactions at 4.5 $A$ GeV/$c$ are performed in the transformed variables and using higher order scaled factorial moments modifyied to remove the bias of infinite statistics in the normalization. The intermittency behavior is found up to eighth order of the m

Lyndon Alvero

We study the sensitivity of the dilepton production cross section to higher twist terms. A method for calculating the resummed cross section is introduced in moment space, where the leading higher twist terms can be easily parametrized and calculated. We find that a $1/Q$ power correction may significantly affect the cross section at fixed-target energies.

J. Ellis, M. Karliner, D. E. Kharzeev, M. G. Sapozhnikov

A large apparent violation of the OZI rule has recently been found in many channels in pbar-p annihilation LEAR. An interpretation of these data in terms of the &#34;shake-out&#34; and &#34;rearrangement&#34; of an intrinsic sbar-s component of the nucleon wave function is proposed. This gives a channel-dependent, non-universal modification of the naive OZI

M. M. Guzzo, O. L. G. Peres, V. Pleitez, R. Zukanovich Funchal

We find an exact analytic solution for the time evolution of a three Dirac neutrino system adiabatically oscillating in matter, constructing explicitly the relevant $3\times 3$ mixing matrix in matter. Using this result we investigate the solar neutrino data in a scenario where the neutrino masses are such that $m_1\alt m_2\ll m_3$, taking into account sever

A. Kundu, S. Mallik

We study the effect of damping on the generation of baryon asymmetry of the Universe in the standard model of the eletroweak theory with simple extensions of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are considered, taking into account their markedly different dispersion relations due to interaction with the hot electroweak plas

Manoranjan Guchait, D. P. Roy

A systematic analysis of the like-sign dipleton signature for gluino production at LHC is performed in the $R$-conserving minimal supersymmetric standard model, taking into account the top quark and Higgs boson effects in the cascade decay. We consider two representative values of the gluino mass, 300 and 800 GeV, along with those of the other SUSY parameter

O. D. Chernavskaya, E. L. Feinberg

The double phase transition of hadronic matter, $H$, first, to the gas of deconfined constituent quarks (for brevity called {\it valons}), $Q$, and then, secondly, the phase transition from $Q$ to quark-gluon plasma, $QGP$, is considered within bag model ideology. In distinction from previous double phase transition investigations, it is not supposed that at

Giuseppe Marchesini

We recall the origin of angular ordering of soft parton emission in the region of small $x$ and show that this coherent structure can be detected in associated distributions. For structure functions at small $x$ and at fixed transverse momentum the angular ordering is masked because of the complete inclusive cancellations of collinear singularities for \xt0.

Steven Weinberg

This is a revised version of a talk given at the Chiral Dynamics Workshop at M.I.T., July 25, 1994. It reports results in three areas: (1) The isospin-violating interactions between one non-relativistic nucleon and any number of soft pions can be summarized in a single term in the effective chiral Lagrangian, with no unknown parameters. (2) With D&#39;Hoker,