November 1993 arXiv papers — page 6

Pietro Santorelli

From the experimental branching ratios for $B^- --> ρ^0 l^-\barν_l$ and $D^+ --> {\overl K}^{*0}({\overl K}^0) e^+ ν_e$ one finds, in the Heavy Quark Limit of $HQET$, $ |V_{bu}|=(8.1\pm 1.7) x 10^{-3}$, larger but consistent with the actual quoted range $(2 - 7) x 10^{-3}$. In the same framework one predicts for $R(B --> K^*γ)=( 2 \pm 2 ) 10^{-2}$.

G. Altarelli, P. Nason, G. Ridolfi

We analyse the available data on the polarized asymmetries $A_1$ for proton, neutron and deuteron targets. We use a homogeneous and updated set of unpolarized structure functions to derive $g_1$ from $A_1$, and we accurately correct for the scaling violations in order to obtain $g_1(x,Q^2)$ with the same $Q^2$ for all $x$ values. The contribution to the $Q^2

Paul Geiger

Mass splittings between the isovector and isoscalar members of meson nonets arise in part from hadronic loop diagrams which violate the Okubo-Zweig-Iizuka rule. Using a model for these loop processes which works qualitatively well in the established nonets, I tabulate predictions for the splittings and associated isoscalar mixing angles in the remaining none

Carl M. Bender, Stefan Boettcher, Lawrence R. Mead

One can define a random walk on a hypercubic lattice in a space of integer dimension $D$. For such a process formulas can be derived that express the probability of certain events, such as the chance of returning to the origin after a given number of time steps. These formulas are physically meaningful for integer values of $D$. However, these formulas are u

Domenico Giulini

We investigate certain properties of the Wheeler-DeWitt metric (for constant lapse) in canonical General Relativity associated with its non-definite nature. Contribution to the conference on Mach's principle: "From Newtons Bucket to Quantum Gravity", July 26-30 1993, Tuebingen, Germany

Kenzo. Ishikawa, Nobuki. Maeda

Bi-local mean field theory is applied to one dimensional quantum liquid with long range $1/r^2$ interaction, which has exact ground state wave function. We obtain a mean field solution and an effective action which expresses a long range dynamics. Based on them the ground state energy and correlation functions are computed. The ground state energy agrees fai

S. Stringari

Various sum rules accounting for the coupling between density and particle excitations and emphasizing in an explicit way the role of the Bose-Einstein condensation are discussed. Important consequences on the fluctuations of the particle operator as well as on the structure of elementary excitations are reviewed. These include a recent generalization of the

I. Bartos, B. Rosenstein

Energies and wave functions of edge states in twodimensional electron gas are evaluated for a finite step potential barrier model. The spectrum exhibits richer structure than observed previously for an infinite barrier model. Surprisingly, instead of smooth Landau level bending in the vicinity of the barrier, the levels acquire a steplike form. These plateau

Min-Chul Cha, S. M. Girvin

The universal conductivity at the zero-temperature superconductor-insulator transition of the two-dimensional boson Hubbard model is studied for cases both with and without magnetic field by Monte Carlo simulations of the (2+1)-dimensional classical $XY$-model with disorder represented by random bonds correlated along the imaginary time dimension. The effect

E. Sorensen, I. Affleck

The structure function, S(k), for the s=1, Haldane gap antiferromagnetic chain, is measured accurately using the recent density matrix renormalization group method, with chain-length 100. Excellent agreement with the nonlinear $σ$ model prediction is obtained, both at $k\approx π$ where a single magnon process dominates and at $k\approx 0$ where a two magnon

Y. Frishman, A. Hanany, M. Karliner

We derive an effective low energy action for QCD in 4 dimensions. The low energy dynamics is described by chiral fields transforming non-trivially under both color and flavor. We use the method of anomaly integration from the QCD action. The solitons of the theory have the quantum numbers of quarks. They are expected to be the constituent quarks of hadrons.

H. Zaidi, J. Gegenberg

The Dirac quantization of a 2+1 dimensional bubble is performed. The bubble consists of a string forming a boundary between two regions of space-time with distinct geometries. The ADM constraints are solved and the coupling to the string is introduced through the boundary conditions. The wave functional is obtained and the quantum uncertainty in the radius o

Robert Garisto

It is well known that supersymmetry (SUSY) gives neutron and electron electric dipole moments ($d_n$ and $d_e$) which are too large by about $10^{3}$. If we assume a SUSY model cannot contain fine-tunings or large mass scales, then one must require that the SUSY breaking mechanism give real soft breaking parameters, in which case the minimal SUSY model has n

G. L. Thomas, N. N. Scoccola, A. Wirzba

Dibaryons configurations are studied in the framework of the bound state soliton model. A generalized axially symmetric ansatz is used to determine the soliton background. We show that once the constraints imposed by the symmetries of the lowest energy torus configuration are satisfied all spurious states are removed from the dibaryon spectrum. In particular

I. I. Bigi, N. G. Uraltsev

We present some straightforward applications of the QCD heavy quark expansion, stated in previous papers [1-3], to the inclusive widths of heavy flavour hadrons. We address the question of the $D_s$ lifetime and argue that -- barring Weak Annihilation (WA) -- $τ(D_s)$ is expected to exceed $τ(D^0)$ by several percent; on the other hand WA could provide a dif

J. P. Garrahan, D. R. Bes

The BRST treatment of triaxial nuclei rotating at high spins, which had been previously developed, is extended to relate states with neighboring values of the angular momentum $I$. As a consequence, the irreducible multipole transition operators can be unambiguously separated into their physical and spurious components. As a by product, we give explicit expr

W. Melnitchouk, A. W. Schreiber, A. W. Thomas

We derive the general structure of the hadronic tensor required to describe deep-inelastic scattering from an off-shell nucleon within a covariant formalism. Of the large number of possible off-shell structure functions we find that only three contribute in the Bjorken limit. In our approach the usual ambiguities encountered when discussing problems related

D. C. Zheng, B. R. Barrett

Two ``phase-shift equivalent'' local NN potentials with different parametrizations, Reid93 and NijmII, which were found to give nearly identical results for the triton by Friar et al, are shown to yield remarkably similar results for 6Li and 14N in a (0+2)hw no-core space shell-model calculation. The results are compared with those for the widely use

José Edelstein, Carlos Nuñez, Fidel Schaposnik

The N=2 supersymmetric extension of the 2+1 dimensional Abelian Higgs model is discussed. By analysing the resulting supercharge algebra, the connection between supersymmetry and Bogomol'nyi equations is clarified. Analogous results are presented when the model is considered in 2-dimensional (Euclidean) space.

S. Aoyama

A topological gravity is obtained by twisting the effective $(2,0)$ super\-gravity. We show that this topological gravity has an infinite number of BRST invariant quantities with conformal weight $0$. They are a tower of OSp$(2,2)$ multiplets and satisfy the classical exchange algebra of OSp$(2,2)$. We argue that these BRST invariant quantities become physic

J. L. Matheus-Valle, M. R-Monteiro

Considering anyonic oscillators in a two-dimensional lattice, we realize the quantum semi-group $sl_{(q,s)}(2)$ by means of a generalized Schwinger construction. We find that the parameter $q$ of the algebra is connected to the statistical parameter, whereas the $s$ parameter is related to a $s$-deformed oscillator introduced at each point of the lattice.

A. Gorsky, A. Johansen

We describe the Hamiltonian reduction of the coajoint Kac-Moody orbits to the Virasoro coajoint orbits explicitly in terms of the Lagrangian approach for the Wess-Zumino-Novikov-Witten theory. While a relation of the coajoint Virasoro orbit $Diff \; S^1 /SL(2,R)$ to the Liouville theory has been already studied we analyse the role of special coajoint Virasor

Anjan Kundu

Results obtained by us are overviewed from a general set up. The universal $R$-matrix is exploited to obtain various important relations and structures involved in quantum group algebra, which are used subsequently for generating different classes of quantum integrable systems through a systematic scheme. This recovers known models as well as discovers a ser

Shailesh Chandrasekharan

A Fermion in 2+1 dimensions, with a mass function which depends on one spatial coordinate and passes through a zero ( a domain wall mass), is considered. In this model, originally proposed by Callan and Harvey, the gauge variation of the effective gauge action mainly consists of two terms. One comes from the induced Chern-Simons term and the other from the c

David R. Morrison

By properly accounting for the invariance of a Calabi-Yau sigma-model under shifts of the $B$-field by integral amounts (analagous to the $θ$-angle in QCD), we show that the moduli spaces of such sigma-models can often be enlarged to include ``large radius limit'' points. In the simplest cases, there are holomorphic coordinates on the enlarged moduli

Ken-ji Hamada

We investigate the Ward identities of the $W_{\infty}$ symmetry in the Liouville theory coupled to the $(p,q)$ conformal matter. The correlation functions are defined by applying the analytic continuation procedure for the matter sector as well as the Liouville one. We then find that the Ward identities are equivalent to the $W_q$ algebra constraints deduced

David Gross

Summary talk at the Lepton-Photon Symposium, Cornell University, Aug. 10-15, 1993.

V. Barger, M. S. Berger, P. Ohmann, R. J. N. Phillips

The scaling behavior of gauge couplings and fermion Yukawa couplings in the minimal supersymmetric model is discussed. The relevance of the top quark Yukawa coupling fixed point in establishing the top quark mass is described. The evolution of mixing angles is presented.

V. Barger, M. S. Berger, P. Ohmann

The scaling behavior and fixed points in the evolution of fermion Yukawa couplings and mixing angles are discussed. The relevance of fixed points in determining the top quark mass is described.

H. Baer, C. Chen, F. Paige, X. Tata

We study the prospects for detecting the sleptons of the Minimal Supersymmetric Standard Model at hadron colliders and supercolliders. We use ISAJET 7.03 to simulate charged slepton and sneutrino pair production, incorporating slepton and sneutrino cascade decays into our analysis. We find that even with an accumulation of $\sim 1$fb$^{-1}$ of integrated lum

Yu. A. Simonov

Perturbative expansion in the nonperturbative confining QCD background is formulated. The properly renormalized $α_S(R)$ is shown to be finite at large distances, with the string tension playing the role of an infrared regulator. The infra--red renormalons are shown to be absent in the new perturbation series.

H. Arthur Weldon

The radiation produced by a classical charged current coupled to a quantized $A_μ$ is first computed. To each order in $α$, all infrared divergences cancel between the virtual $γ$'s and the real $γ$'s that are absorbed from or emitted into the plasma. When all orders of perturbation theory are summed, the finite answer predicts a suppression of radia

P. H. Damgaard, R. Sollacher

Qualitons, topological excitations with the quantum numbers of quarks, may provide an accurate description of what is meant by constituent quarks in QCD. Their existence hinges crucially on an effective Lagrangian description of QCD in which a pseudoscalar colour-octet of fields enters as a new variable. We show here how such new fields may be extracted from

William Pezzaglia, Alfred Differ

Multivector quantum mechanics utilizes wavefunctions which are Clifford aggregates (e.g. sum of scalar, vector, bivector). This is equivalent to multi- spinors constructed of Dirac matrices, with the representation independent form of the generators geometrically interpreted as the basis vectors of spacetime. Multiple generations of particles appear as left

S. Stringari

Various bounds for the energy of collective excitations in the Heisenberg antiferromagnet are presented and discussed using the formalism of sum rules. We show that the Feynman approximation significantly overestimates (by about 30\% in the $S={1\over2}$ square lattice) the spin velocity due to the non negligible contribution of multi magnons to the energy w

M. Yu. Lashkevich

It is well known$^{1,2}$ that in one-dimensional disordered system all states of electrons (or any other exitations) are localized. In this letter it is shown that delocalized states exist in a rather broad class of of simple models, but a set of delocalized states is not too great, and it does not contradict this theorem in more precize form$^{2,3}$. These

C. L. Kane, K. A. Matveev, L. I. Glazman

The photon-absorption edge in a weakly interacting one-dimensional electron gas is studied, treating backscattering of conduction electrons from the core hole exactly. Close to threshold, there is a power-law singularity in the absorption, $I(ε) \propto ε^{-α}$, with $α= 3/8 + δ_+/π- δ_+^2/2π^2$ where $δ_+$ is the forward scattering phase shift of the core h

Diego Harari, Matias Zaldarriaga

We evaluate the large scale polarization of the cosmic microwave background induced, via Thomson scattering prior to decoupling, by nearly scale-invariant spectra of scalar and tensor metric perturbations, such as those predicted by most inflationary models of the early Universe. We solve the radiative transfer equation for the polarized photon distribution

Andrew H. Jaffe

We consider the evolution of perturbations to a flat FRW universe that arise from a ``stiff source,'' such as a self-ordering cosmic field that forms in a global symmetry-breaking phase transition and evolves via the Kibble mechanism. Although the linear response of the normal matter to the source depends on the details of the source dynamics, we sho

B. Dorman, R. Rood, R. O'Connell

This series of papers comprises a systematic exploration of the hypothesis that the far ultraviolet radiation from star clusters and elliptical galaxies originates from extremely hot horizontal-branch (HB) stars and their post-HB progeny. This first paper presents an extensive grid of calculations of stellar models from the Zero Age Horizontal Branch through

T. Schramm

We introduce a formalism to describe 2D-Potentials for 2D-matter (or charge) distributions with arbitrary elliptical symmetry including varying eccentricity and twisting of the iso-density curves. We use this approach to describe elliptical matter distributions such as elliptical galaxies or clusters as gravitational lenses. Figures are available upon reques

Ciro Ciliberto, Angelo Lopez, Rick Miranda

In this article we exhibit certain projective degenerations of smooth $K3$ surfaces of degree $2g-2$ in $\Bbb P^g$ (whose Picard group is generated by the hyperplane class), to a union of two rational normal scrolls, and also to a union of planes. As a consequence we prove that the general hyperplane section of such $K3$ surfaces has a corank one Gaussian ma

Ivaylo Zlatev, Wei-Min Zhang, Da Hsuan Feng

We construct the most general SO(4,2) hydrogen atom coherent states which are the counterpart of Schrödinger's harmonic oscillator coherent states. We show that these states cannot be localized and cannot follow the classical orbits. Thus, Schrödinger's conjecture for the hydrogen atom coherent states is unattainable.

Sy D. Friedman

In this paper we isolate the notion of Stratified class forcing and show that Stratification implies cofinality-preservation and is preserved by iterations with the appropriate support. Many familiar class forcings are stratified and therefore can be simultaneously iterated without changing cofinalities, provided the proper support is used. Easton forcing, B

S. Pratik Khastgir, Alok Kumar

It is shown that new leading ($\al'$) as well as all-order solutions of String theory can be obtained by taking appropriate singular limits of the known solutions. We give several leading order solutions for the bosonic as well as the heterotic string. We then present all-order forms of the previously known two dimensional cosmological solutions. An all-

Klaus Lang, Werner Ruehl

The classification of quasi - primary fields is outlined. It is proved that the only conserved quasi - primary currents are the energy - momentum tensor and the O(N) - Noether currents. Derivation of all quasi - primary fields and the resolution of degeneracy is sketched. Finally the limits d=2 and d=4 of the space dimension are discussed. Whereas the latter

S. Kojima, N. Sakai, Y. Tanii

Supergravity theory in $2+ε$ dimensions is studied. It is invariant under supertransformations in 2 and 3 dimensions. One-loop divergence is explicitly computed in the background field method and a nontrivial fixed point is found. In quantizing the supergravity, a gauge fixing condition is devised which explicitly isolates conformal and superconformal modes.

P. Maslanka

The global counterpart of $k$-Poincare algebra is considered. The induced representations of this group are described. The explicit form of the covariant wave functions in the `minimal' (in Weinberg's sense) case is given.

V. I. Man'ko

The review of the following results of the Refs. \cite{Sem} - \cite{Ans} is presented: For mixed state light of $N$-mode electromagnetic field described by Wigner function which has generic Gaussian form the photon distribution function is obtained and expressed expliciltly in terms of Hermite polynomials of $2N$-variables.The momenta of this distribution ar

Paul S. Aspinwall, Brian R. Greene, David R. Morrison

We analyze global aspects of the moduli space of Kähler forms for $N$=(2,2) conformal $σ$-models. Using algebraic methods and mirror symmetry we study extensions of the mathematical notion of length (as specified by a Kähler structure) to conformal field theory and calculate the way in which lengths change as the moduli fields are varied along distinguished

Paul B. Mackenzie

Significant progress has recently been achieved in the lattice gauge theory calculations required for extracting the fundamental parameters of the standard model from experiment. Recent lattice determinations of such quantities as the kaon $B$ parameter, the mass of the $b$ quark, and the strong coupling constant have produced results and uncertainties as go

J. Lopez, D. Nanopoulos, A. Zichichi

The determination of the most straightforward evidence for the existence of the Superworld requires a guide for non-experts (especially experimental physicists) for them to make their own judgement on the value of such predictions. For this purpose we review the most basic results of Super-Grand unification in a simple and clear way. We focus the attention o

Stamatis Vokos

(Talk presented at the 3rd Workshop on Thermal Field Theories and Their Applications, Banff, Canada, August 1993. This is a review of work done with Peter Arnold, Paulo Bedaque, and Ashok Das.) We demonstrate that one-loop self-energies at finite temperature have a unique limit as the external four-momentum goes to zero, as long as the particles propagating

L. McLerran

I discuss the problem of computing B + L violation at high energies as that of solving classical differential equations. These equations involve boundary conditions at initial and a final times which are anti-Feynman, and involve solving non-linear differential equations which are complex, even if the original Hamiltonian was real.

N. N. Nikolaev, B. G. Zakharov

The 1993 witnessed two major news in the field of color transparency (CT): i) no effect of CT was seen in the SLAC NE18 experiment on $A(e,e'p)$ scattering at virtualities of the exchanged photon $Q^{2} \lsim 7$ GeV$^{2}$, ii) strong signal of CT was observed in the Fermilab E665 experiment on exclusive $ρ^{0}$-meson production in deep inelastic scatteri

B. Z. Kopeliovich, J. Nemchick, N. N. Nikolaev, and B. G. Zakharov

The exclusive production of vector mesons in deep inelastic scattering is a hard scattering process with the well controlled size of quark configurations which dominate the production amplitude. This allows an unambiguous prediction of color transparency effects in the coherent and incoherent production of vector mesons on nuclei. We demonstrate how the very

Edmond Iancu

It is shown that the long wavelength excitations of a quark-gluon plasma may be described as collective oscillations of self-consistent average fields to which the plasma particles couple. Their properties are obtained from a set of coupled mean field and kinetic equations, derived from the general Dyson-Schwinger equations, as the leading order in a systema

V. Khatsymovsky

Considered are I class constraints in the tetrad-connection formulation of Regge calculus. One of these is well-known Gauss law which generates rotations in the local frames associated with tetrahedrons in the continuous time 3D section. Another two types of these are new, satisfied by definition of Regge manifold and having no I class analogs in the continu

Uwe Brauer, Edward Malec, Niall Ó Murchadha

Consider spherically symmetric initial data for a cosmology which, in the large, approximates an open $k = -1 ,Λ= 0$ Friedmann-Lema{\^ı}tre universe. Further assume that the data is chosen so that the trace of the extrinsic curvature is a constant and that the matter field is at rest at this instant of time. One expects that no trapped surfaces appear in the

Daniel Kennefick, Niall Ó Murchadha

The assumption that a solution to the Einstein equations is static (or stationary) very strongly constrains the asymptotic behaviour of the metric. It is shown that one need only impose very weak differentiability and decay conditions {\it a priori} on the metric for the field equations to force the metric to be analytic near infinity and to have the standar

Harald H. Soleng

Near a spinning point particle in (2+1)-dimensional gravity (or near an infinitely thin, straight, spinning string in 3+1 dimensions) there is a region of space-time with closed timelike curves. Exact solutions for extended sources with apparently physically acceptable energy-momentum tensors, have produced the same exterior space-time structure. Here it is

M. Baake, U. Grimm, C. Pisani

The study of zeros of partition functions, initiated by Yang and Lee, provides an important qualitative and quantitative tool in the study of critical phenomena. This has frequently been used for periodic as well as hierarchical lattices. Here, we consider magnetic field and temperature zeros of Ising model partition functions on several aperiodic structures

L. F. Cugliandolo, J. Kurchan

We derive analytical results for the large-time relaxation of the Sherrington - Kirkpatrick model in the thermodynamic limit, starting from a random configuration. The system never achieves local equilibrium in any fixed sector of phase-space, but remains in an asymptotic out of equilibrium regime. We propose as a tool, both numerical and analytical, for the

C. Gruber, D. Ueltschi, J. Jȩdrzejewski

The ground state configurations of the one--dimensional Falicov--Kimball model are studied exactly with numerical calculations revealing unexpected effects for small interaction strength. In neutral systems we observe molecular formation, phase separation and changes in the conducting properties; while in non--neutral systems the phase diagram exhibits Farey

Sang-Yoon Kim

We study the critical behavior of period doubling in two coupled one-dimensional maps with a single maximum of order $z$. In particurlar, the effect of the maximum-order $z$ on the critical behavior associated with coupling is investigated by a renormalization method. There exist three fixed maps of the period-doubling renormalization operator. For a fixed m

C. Bernard, P. Hsieh, A. Soni

A lattice calculation of the form factors that determine the ``hadronization ratios'', such as $R_{K^*}$ and $R_{\phi}$, where $R_{K^*} \equiv [\Gamma ($B \to K^* \gamma$)/\Gamma(b \to s \gamma)]$, is presented in the quenched approximation. Lattice data shows strong evidence for the scaling law suggested by heavy quark symmetry for one of the form factors (

Mark D. Gould, Yao-Zhong Zhang

Let $U_q(\hat{\cal G})$ be an infinite-dimensional quantum affine Lie algebra. A family of central elements or Casimir invariants are constructed and their eigenvalues computed in any integrable irreducible highest weight representation. These eigenvalue formulae are shown to absolutely convergent when the deformation parameter $q$ is such that $|q|>1$. It i

Edoardo Ballico, Jaroslaw Wisniewski

In the present paper we discuss coherent sheaves of rank > 1 whose projectivization gives rise to smooth varieties - varieties of this type are also called smooth scrolls. We prove some basic properties of these varieties and we give some pertinent examples. We classify Fano manifolds of large index which are of this type.

M. Jeżabek, J. H. Kühn, T. Teubner

The behavior of the momentum distribution of top quarks in the threshold region is investigated. The qualitative behavior, in particular the dependence of the average momentum on the strong coupling constant can be understood from analytical calculations for the Coulomb potential. Ambiguities in the relation between the excitation curve and the top mass are

Richard F. Lebed

Baryon decuplet masses within an $SU(3)_L \times SU(3)_R$ chiral Lagrangian formalism are found to satisfy four relations at second order in flavor breaking. As a result, the one-loop corrections from Lagrangian terms up to first order in flavor breaking are observed to give finite and calculable corrections to these relations. The formal expressions for the

Abhay Ashtekar, Jerzy Lewandowski

Integral calculus on the space of gauge equivalent connections is developed. Loops, knots, links and graphs feature prominently in this description. The framework is well--suited for quantization of diffeomorphism invariant theories of connections. The general setting is provided by the abelian C* algebra of functions on the quotient space of connections gen

Carlberg

To test whether clusters have rising mass to light ratios at large radii and to estimate the amplitude of the density fluctuation spectrum on the scale of 10\hmpc\ the Canadian Network for Observational Cosmology (CNOC) cluster collaboration is obtaining Multi-Object Spectrograph velocities and two colour photometry for a sample of $\simeq$1000 cluster galax

Vitaly Tarasov, Alexander Varchenko

The quantized Knizhnik-Zamolodchikov equations associated with the trigonometric R-matrix or the rational R-matrix of the A-type are considered. Jackson integral representations for solutions of these equations are described. Asymptotic solutions for a holonomic system of difference equations are constructed. Relations between the integral representations an

Y. Kayama, H. Anada, Y. Imamura, 9 pages

We propose a characteristic representation ofone-dimensional and 2-state, 3-neighbor cellular automaton rules, which describes an effective form of each rule after many time steps. Simulated results of the representation show that complex structures of Class IV rules come from their aspects of Class II and III. Class IV-like patterns can be generated by char

Michael Martin Nieto

Both the coherent states and also the squeezed states of the harmonic oscillator have long been understood from the three classical points of view: the 1) displacement operator, 2) annihilation- (or ladder-) operator, and minimum-uncertainty methods. For general systems, there is the same understanding except for ladder-operator and displacement-operator squ

Paul A. Kimoto, David F. Chernoff

We investigate asymptotic convergence in the~$Δx \!\rightarrow\! 0$ limit as a tool for determining whether numerical computations involving shocks are accurate. We use one-dimensional operator-split finite-difference schemes for hydrodynamics with a von Neumann artificial viscosity. An internal-energy scheme converges to demonstrably wrong solutions. We ass

S. A. Bonometto, S. Borgani, S. Ghigna, A. Klypin

We use high resolution PM N-body simulations to follow the development of non-linear clustering in a flat Universe, dominated by Cold + Hot Dark Matter (CHDM) with 60% of CDM, 30% of HDM and 10% of baryons; a simulation box of 100 Mpc a side ($h=0.5$) is used. We analyze two CHDM simulations with $b =1.5$ (COBE normalization). We also compare them with CDM s

Shin-ichi Sasa, Ken Sekimoto

Crack propagations in quasi-static fracture are studied theoretically. The Griffith theory is applied to discuss a crack extension condition and motion of crack tips in straight propagations. Stability of the straight propagations is investigated based on the simple assumption that a curvature near the crack tip is determined by a singular shear stress. It i

H. -C. Jean, J. Piekarewicz, A. G. Williams

We calculate the effective mass of the $ω$ meson in nuclear matter in a relativistic random-phase approximation to the Walecka model. The dressing of the meson propagator is driven by its coupling to particle-hole pairs and nucleon-antinucleon ($N\bar{N}$) excitations. We report a reduction in the $ω$-meson mass of about 170~MeV at nuclear-matter saturation

S. Ferrara, A. Masiero, M. Porrati, R. Stora

We construct the Bardeen anomaly and its related Wess-Zumino term in the supersymmetric standard model. In particular we show that it can be written in terms of a composite linear superfield related to supersymmetrized Chern-Simons forms, in very much the same way as the Green-Schwarz term in four-dimensional string theory. Some physical applications, such a

L. N. Lipatov

The quantum inverse scattering method is applied to the solution of equations for wave functions of compound states of $n$ reggeized gluons in the multicolour QCD in a generalized leading logarithmic approximation.

Martin Schlichenmaier

Invited talk at the International Symposium on Generalized Symmetries in Physics at the Arnold-Sommerfeld-Institute, Clausthal, Germany, July 26 -- July 29, 1993. This talk reviews results on the structure of algebras consisting of meromorphic differential operators which are holomorphic outside a finite set of points on compact Riemann surfaces. For each pa

Mikhail V. Saveliev

On an equation associated with the contact Lie algebras/ Mikhail V. Saveliev/ In the framework of a Lie algebraic approach we study a nonlinear equation associated with the contact Lie algebra ${\bf K}K_m$, that seems to be relavant for some solvable models of field theory and gravity in higher dimensions. LPTENS--93/43.

Nathan Weiss

There have been several talks at this workshop on the physical interpretation and consequences of the $Z_N$ symmetry which is present in the Euclidean Path Integral formulation of $SU_N$ Gauge Theories at finite temperature. The purpose of this paper is to present an introduction to this subject. After a brief review of Gluodynamics at finite temperature, th

Matthias Neubert

The formalism of the heavy quark effective theory is used to derive the field-theory analog of the virial theorem, which relates the matrix element of the kinetic energy of a heavy quark inside a hadron to a matrix element of the gluon field strength tensor. The existing QCD sum rule calculations of the kinetic energy are not consistent with this theorem.

F. De Campos, JosÉ W. F. Valle

We show that the possibility of having light gluinos is not in conflict with recent LEP measurements and also that cosmology does not rule it out in any convincing way. In unified N=1 supergravity models, one expects that also the "photino" will be light. Moreover it leads to $upper$ limits on the masses of the other supersymmetric fermions, for exam

M. Plümer, L. V. Razumov, R. M. Weiner

Bounds for the correlation functions of identical bosons are discussed for the general case of a Gaussian density matrix. In particular, for a purely chaotic system the two-particle correlation function must always be greater than one. On the other hand, in the presence of a coherent component the correlation function may take values below unity. The experim

S. Yu. Khlebnikov

We compute one-loop effective action of magnetic monopole in three-dimensional electrodynamics of massless bosons and fermions and find that it contains an infrared logarithm. So, when the number of massless matter species is sufficiently large, monopoles are suppressed and in the weak coupling limit charged particles are unconfined. This result provides som

Marco Aurelio Diaz

It is analyzed the branching ratio $B(b\rightarrow sγ)$ in the context of minimal $N=1$ supergravity with radiatively broken electroweak symmetry group. There is a strong dependence on supersymetric parameters, but constraints on the charged Higgs mass in non-supersymmetric models are relaxed, due to large contribution from the chargino/up-type squark sector

Gunnar S. Bali

A recent lattice calculation of the QCD running coupling is presented. The coupling is extracted from the force between two static quarks in the framework of the valence quark approximation. A value of the Lambda-parameter for zero quark flavours is determined: Lambda_msbar=0.630(38)\sqrtσ =293(18)^{+25}_{-63} MeV. The first error is statistical, the second

P. Menotti, D. Seminara

In this paper we report some results obtained by applying the radial gauge to 2+1 dimensional gravity. The general features of this gauge are reviewed and it is shown how they allow the general solution of the problem in terms of simple quadratures. Then we concentrate on the general stationary problem providing the explicit solving formulas for the metric a

José P. S. Lemos, Paulo M. Sá

A general dilaton gravity theory in 1+1 spacetime dimensions with a cosmological constant $λ$ and a new dimensionless parameter $ω$, contains as special cases the constant curvature theory of Teitelboim and Jackiw, the theory equivalent to vacuum planar General Relativity, the first order string theory, and a two-dimensional purely geometrical theory. The eq

S. Carlip, J. E. Nelson

For spacetimes with the topology $\IR\!\times\!T^2$, the action of (2+1)-dimensional gravity with negative cosmological constant $\La$ is written uniquely in terms of the time-independent traces of holonomies around two intersecting noncontractible paths on $T^2$. The holonomy parameters are related to the moduli on slices of constant mean curvature by a tim

Elbio Dagotto

Theoretical ideas and experimental results concerning high temperature superconductors are reviewed. Special emphasis is given to calculations carried out with the help of computers applied to models of strongly correlated electrons proposed to describe the two dimensional ${\rm Cu O_2}$ planes. The review also includes results using several analytical techn

D. Dominici, U. Marini Bettolo Marconi

We compute the corrections of next to leading order in the ${1 \over N}$ expansion to the effective potential of a system described by a Ginzburg-Landau model with $N$ components and quartic interaction, in the case of spontaneous symmetry breaking. The method we apply allows to generalize in a simple way the so-called Self-Consistent Screened Approximation

R. A. Battye, E. P. S. Shellard

We study Goldstone boson (or axion) radiation from global $U(1)$-strings making direct quantitative comparisons between numerical scalar field theory simulations and linearized analytic calculations in the dual antisymmetric tensor representation. Concentrating on periodic long string configurations, we show excellent correspondence for both the amplitude an

F. Scappini, G. G. C. Palumbo, G. Bruni, P. Bergman

This paper is intended as part of a more extensive molecular line survey in star forming regions along the evolutionary track of a collapsing cloud toward a young stellar object. We have studied a sample of seven small dark clouds (Bok globules) and eight Herbig Ae/Be stars in the J=1->0 transition of HCO$^{+}$, H$^{13}$CO$^{+}$, HCN and H$^{13}$CN. The choi

Istvan Racz

We consider the 3-dimensional formulation of Einstein's theory for spacetimes possessing a non-null Killing field $ξ^a$. It is known that for the vacuum case some of the basic field equations are deducible from the others. It will be shown here how this result can be generalized for the case of essentially arbitrary matter fields. The systematic study of

R. D. Benguria, M. C. Depassier

We obtain an upper bound on the value of $λ$ for which monotonic front solutions of the equation $λu''' + u' = f(u)$ with $λ> 0$ may exist.

Hitoshi Nakada, Takaharu Otsuka

E2 properties of A=6--10 nuclei, including those of nuclei far from stability, are studied by a $(0+2)\hbarω$ shell-model calculation which includes E2 core-polarization effects explicitly. The quadrupole moments and the E2 transition strengths in A=6--10 nuclei are described quite well by the present calculation. This result indicates that the relatively la