March 1995 arXiv papers — page 9

R. Ramaty, R. E. Lingenfelter

We review the wide range of astrophysical observations of gamma ray emission lines and we discuss their implications. We consider line emission from solar flares, the Orion molecular cloud complex, supernovae 1987A and 1991T, the supernova remnants Cas A and Vela, the interstellar medium, the Galactic center region and several Galactic black hole candidates.

Ulrich Lindner, Jaan Einasto, Maret Einasto, Wolfram Freudling

Supervoids are regions in the local Universe which do not contain rich clusters of galaxies. We have studied the closest example, the Northern Local Void, situated between the Local, Coma, and the Hercules superclusters. We find that this supervoid is not empty, but it contains small galaxy systems and poor clusters of galaxies. We study the cosmography of t

M. Jaroszynski, B. Paczynski

Geometrical optics provides an excellent description for quasar images crossing caustics which are formed by gravitational microlensing of objects like Q2237+0305. Within this approximation the source size can be estimated from the maximum magnification reached at caustic crossings. We evaluate the limitations imposed by diffraction on caustics using the for

Robert C. Ferrell, Edmund Bertschinger

We present a computational algorithm for computing short range forces between particles. The algorithm has two distinguishing features. First, it is optimized for multi-processor computers, and will use as many processors as are available. Second, it is optimized for inhomogeneous, dynamic particle distributions; for any distribution the computational load i

Joao M. Soares

The radiative decays of the B mesons may have a significant contribution from the transition b -> s J/psi followed by the J/psi-photon conversion. The size of this contribution is re-analysed in the light of a phenomenological model for the weak bsJ/psi vertex, and a modified J/psi-photon interaction that is manifestly gauge invariant. Predictions for both i

P. Saltsidis

The Hamiltonian BRST quantization of the null spinning string for different number of supersymmetries is given. A null spinning string with manifest space-time conformal invariance is constructed. Its Brst quantization gives negative critical dimension for $N\neq 0$ and reproduces previous results for $N=0$.

PH. Jacquod, J. -P. Amiet

We study the statistical properties of the spectrum of a quantum dynamical system whose classical counterpart has a mixed phase space structure consisting of two regular regions separated by a chaotical one. We make use of a simple symmetry of the system to separate the eigenstates of the time-evolution operator into two classes in agreement with the Perciva

M. Ciuchini, E. Franco, G. Martinelli, L. Reina

We review the latest calculations of the next-to-leading $\DSone$ effective Hamiltonian, relevant for $K\to ππ$ transitions. Numerical results for the Wilson coefficients are given for different regularization schemes. Predictions of $\epse$, obtained using different approaches to evaluate the relevant hadronic matrix elements, are compared. Given the presen

Costas G. Papadopoulos

We present the full tree-order calculation of the process $e^+e^-\to\ell\barν_\ell\; q \bqp$ including the width effects in a way which is consistent with gauge invariance and high energy unitarity and which has a natural interpretation within standard perturbation theory. We also include C- and P-preserving deviations from Standard Model trilinear vector bo

Andreas Cap, Jan Slovak, Vladimir Soucek

In the first part of this series of papers we developed the invariant differentiation with respect to a Cartan connection, we described this procedure in the terms of the underlying principal connections, and we discussed applications of this theory to the construction of natural operators. In this part we will extend the results of \cite{Ochiai, 70} on the

Andreas Cap, Jan Slovak, Vladimir Soucek

This is the first part of a series of papers. The whole series aims to develop the tools for the study of all almost Hermitian symmetric structures in a unified way. In particular, methods for the construction of invariant operators, their classification and the study of their properties will be worked out. In this paper we present the invariant differentiat

D. Louis-Martinez, G. Kunstatter

The most general two-dimensional dilaton gravity theory coupled to an Abelian gauge field is considered. It is shown that, up to spacetime diffeomorphisms and $U(1)$ gauge transformations, the field equations admit a two-parameter family of distinct, static solutions. For theories with black hole solutions, coordinate invariant expressions are found for the

Keith R. Dienes, Moshe Moshe, Robert C. Myers

We demonstrate that string consistency in four spacetime dimensions leads to a spectrum of string states which satisfies the supertrace constraints Str(M^0)=0 and Str(M^2)=Λat tree level, where Λis the one-loop string cosmological constant. This result holds for a large class of string theories, including critical heterotic strings. For strings lacking space

K. Berndl, D. Dürr, S. Goldstein, G. Peruzzi

We show that the particle motion in Bohmian mechanics, given by the solution of an ordinary differential equation, exists globally: For a large class of potentials the singularities of the velocity field and infinity will not be reached in finite time for typical initial values. A substantial part of the analysis is based on the probabilistic significance of

M. Bordemann, M. Brischle, C. Emmrich, S. Waldmann

We derive a closed formula for a star-product on complex projective space and on the domain $SU(n+1)/S(U(1)\times U(n))$ using a completely elementary construction: Starting from the standard star-product of Wick type on $C^{n+1} \setminus \{ 0 \}$ and performing a quantum analogue of Marsden-Weinstein reduction, we can give an easy algebraic description of

C. Alexandrou, F. K. Diakonos

The variational approach, used by Feynman in the study of the polaron problem, is generalized to treat a system of N non-relativistic particles interacting with scalar and vector mesons. After integrating out the meson fields in the path integral formulation we perform a variational calculation for the effective N-body two-time action to obtain the energy an

L. C. Liu, Q. Haider, J. T. Londergan

The momentum-space cut-off parameter $Λ$ of hadronic vertex functions is studied in this paper. We use a composite model where we can measure the contributions of intermediate particle propagations to $Λ$. We show that in many cases a composite vertex function has a much smaller cut-off than its constituent vertices, particularly when light constituents such

Veerle Van der Sluys, Jan Ryckebusch, Michel Waroquier

The longitudinal and transverse structure functions are calculated for inclusive electron scattering from ${}^{12}$C and ${}^{40}$Ca in the quasielastic and dip region. The microscopic model presented here incorporates two-body currents derived from one-pion exchange and intermediate $Δ$ excitation. The reaction mechanism involves both one-nucleon and two-nu

Jan Ryckebusch, Marc Vanderhaeghen, Kris Heyde, Michel Waroquier

The influence of short-range correlations (SRC) on the triple-coincidence (e,e$'$pp) reactions is studied. The non-relativistic model uses a mean-field potential to account for the distortions that the escaping particles undergo. Apart from the SRC, that are implemented through a Jastrow ansatz with a realistic correlation function, we incorporate the co

Michael J. Mehl, Dimitrios A. Papaconstantopoulos

A new tight-binding total energy method, which has been shown to accurately predict ground state properties of transition and noble metals, is applied to Manganese, the element with the most complex ground state structure among the $d$ metals. We show that the tight-binding method correctly predicts the ground state structure of Mn, and offers some insight i

Donald E. Knuth

A pleasant family of graphs defined by Godsil and McKay is shown to have easily computed eigenvalues in many cases.

François Lalonde, Dusa McDuff

In this paper we first show that the necessary condition introduced in our previous paper is also a sufficient condition for a path to be a geodesic in the group $\Ham^c(M)$ of compactly supported Hamiltonian symplectomorphisms. This applies with no restriction on $M$. We then discuss conditions which guarantee that such a path minimizes the Hofer length. Ou

François Lalonde, Dusa McDuff

Consider the group $\Ham^c(M)$ of compactly supported Hamiltonian symplectomorphisms of the symplectic manifold $(M,\om)$ with the Hofer $L^{\infty}$-norm. A path in $\Ham^c(M)$ will be called a geodesic if all sufficiently short pieces of it are local minima for the Hofer length functional $\Ll$. In this paper, we give a necessary condition for a path $\ga$

Ronald Brown, Christopher D. Wensley

Results on the finiteness of induced crossed modules are proved both algebraically and topologically. Using the Van Kampen type theorem for the fundamental crossed module, applications are given to the 2-types of mapping cones of classifying spaces of groups. Calculations of the cohomology classes of some finite crossed modules are given, using crossed compl

G. Papadopoulos

We find a new class of (2,0)-supersymmetric two-dimensional sigma models with torsion and target spaces almost complex manifolds extending similar results for models with (2,2) supersymmetry. These models are invariant under a new symmetry which is generated by a Noether charge of Lorentz weight one and it is associated to the Nijenhuis tensor of the almost

C. Duval, P. A. Horváthy, L. Palla

The non-relativistic `Dirac' equation of Lévy-Leblond is used to describe a spin {\small 1/2} particle interacting with a Chern-Simons gauge field. Static, purely magnetic, self-dual spinor vortices are constructed. The solution can be `exported' to a uniform magnetic background field.

V. P. Frolov, A. L. Larsen

A general description of string excitations in stationary spacetimes is developed. If a stationary string passes through the ergosphere of a 4-dimensional black hole, its world-sheet describes a 2-dimensional black (or white) hole with horizon coinciding with the static limit of the 4-dimensional black hole. Mathematical results for 2-dimensional black holes

Ashoke Sen

The equations of motion of the massless sector of the two dimensional string theory, obtained by compactifying the heterotic string theory on an eight dimensional torus, is known to have an affine o(8,24) symmetry algebra generating an O(8,24) loop group. In this paper we study how various known discrete S- and T- duality symmetries of the theory are embedde

R Delbourgo

Allowing for the inclusion of the parity operator, it is possible to construct an oscillator model whose Hamiltonian admits an EXACT square root, which is different from the conventional approach based on creation and annihilation operators. We outline such a model, the method of solution and some generalizations.

V. I. Matveev, S. G. Tolmanov

The energy losses at collisions of heavy multiplycharged ions with light atoms have been considered under circumstances the ion charge Z>>1 and the relative colliding velocity v>>1, so that Z~v=<c, where c - the light velocity (atomic units are used). In this region of parameters the Born approximation are not justificative. The simple formulas for effective

Chih-Hao Chen

The potential of seeing supersymmetry (SUSY) at the CERN Large Hadron Collider (LHC) was studied by looking at 3 types of signals: dilepton events from slepton pair productions, trilepton events from chargino/neutralino productions and missing energy plus multi-jet events from gluino/squark productions. I described my results by mapping out reachable areas i

M. Drees

The upper bond on the branching ratio for $b\to sγ$ decays implies a stringent lower bound on the mass of the pseudoscalar Higgs boson of the MSSM if sparticles are heavy. This leads to an upper bound on the expected event rate in experiments searching for heavy supersymmetric dark matter. Scenarios with lighter sparticle spectrum and light pseudoscalar Higg

S. Bornholdt, N. Tetradis, C. Wetterich

Two-scalar theories at high temperature exhibit a rich spectrum of possible critical behaviour, with a second or first order phase transition. In the vicinity of the critical temperature one can observe critical exponents, tricritical points and crossover behaviour. None of these phenomena are visible to high temperature perturbation theory.

W. M. Alberico, M. Nardi, S. Quattrocolo

We present a model for quark matter with a density dependent quark-quark (confining) potential, which allows to describe a deconfinement phase transition as the system evolves from a low density assembly of bound structures to a high density free Fermi gas of quarks. A proper account of the many-body correlations induced by the medium is crucial in order to

E. E. Boos, M. N. Dubinin, V. A. Ilyin, A. E. Pukhov

At present time when a new generation of TeV colliders are beginning to operate one needs to calculate cross-sections for a great number of various reactions. Such calculations are united in the framework of the collider physical program, providing definite predictions how to detect the signatures of the new physics and separate them from the background. The

Robin G. Stuart

The Standard Model Lagrangian requires the values of the fermion masses, the Higgs mass and three other experimentally well-measured quantities as input in order to become predictive. These are typically taken to be $α$, $G_μ$ and $M_Z$. Using the first of these, however, introduces a hadronic contribution that leads to a significant error. If a quantity cou

S. M. Troshin, N. E. Tyurin

We consider mechanism for one-spin asymmetries observed in inclusive hadron production. The main role belongs to the orbital angular momentum of the quark-antiquark cloud in the internal structure of constituent quarks. We argue that the origin of the asymmetries in pion production is a result of retaining of this internal angular orbital momentum by the per

Yasuhiko Nagoshi, Ken Nakanishi

The fermion mass matrices are calculated in the framework of the dynamical mass generation by the broken horizontal gauge interactions. The non-proportional mass spectra between up- and down-sectors and CKM mixings are obtained solely by radiative corrections due to the ordinary gauge interactions.

I. Montvay

The $N=2$ supersymmetric continuum limit is investigated in the SU(2) adjoint Higgs-Yukawa model using lattice perturbation theory. In the one-loop renormalization group equations a non-trivial infrared fixed point of coupling ratios is found. The phase structure at weak couplings is determined by a numerical study of the one-loop effective potential.

J. F. Wheater

We report on a high statistics numerical study of the crystalline random surface model with extrinsic curvature on lattices of up to $64^2$ points. The critical exponents at the crumpling transition are determined by a number of methods all of which are shown to agree within estimated errors. The correlation length exponent is found to be $ν=0.71(5)$ from th

The CDF Collaboration

We present a measurement of the mass of the $W$ boson using data collected with the CDF detector during the 1992-93 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 3268 {\mbox{$W \rightarrow μν$}} events recorded in an integrated luminosity of 19.7 pb$^{-1}$ gives a mass $M_{W}^μ=80.310\pm0.205\mbox{~(stat.)}\pm0.1

Mariusz P. Dabrowski

The non-singular, oscillating Friedman cosmology within the framework of General Relativity is considered. The general oscillatory solution given in terms of elliptic functions and the conditions for its existence are discussed. It is shown that the wall-like-matter and the small, but negative cosmological constant are required for oscillations. The oscillat

Marc Mezard

Contents: I. Introduction II. Manifolds in random media III. Thermal fluctuations without disorder IV. Random forces V. Random potential: variational approach VI. Physical interpretation of the solution

J. Beenen, D. M. Edwards

Quasiparticle bands of the two-dimensional Hubbard model are calculated using the Roth two-pole approximation to the one particle Green&#39;s function. Excellent agreement is obtained with recent Monte Carlo calculations, including an anomalous volume of the Fermi surface near half-filling, which can possibly be explained in terms of a breakdown of Fermi liq

Kikuo Harigaya, Yukihiro Shimoi, Shuji Abe

Exciton effects on soliton and bipolaron lattice states are investigated using an electron-lattice Peierls model with long-range Coulomb interactions. The Hartree-Fock (HF) approximation and the single-excitation configuration-interaction (single-CI) method are used to obtain optical absorption spectra. We discuss the following properties: (1) The attraction

K. Frahm, A. Mueller-Groeling, J. -L. Pichard, D. Weinmann

The pair localization length $L_2$ of two interacting electrons in one--dimensional disordered systems is studied numerically. Using two direct approaches, we find $L_2 \propto L_1^α$, where $L_1$ is the one-electron localization length and $α\approx 1.65$. This demonstrates the enhancement effect proposed by Shepelyansky, but the value of $α$ differs from p

R. J. Radtke, S. Das Sarma

Using a mean-field theory, we study the possible existence of a spin-triplet intersubband exciton liquid ground state in semiconductor quantum well systems as a function of the electronic density and the strength of the intersubband Coulomb interaction matrix element at low temperatures. We find the excitonic phase to be stable over a large region of paramet

Bulbul Chakraborty, Zhigang Xi

We study the early-stages of ordering in $Cu_3 Au$ using a model Hamiltonian derived from the effective medium theory of cohesion in metals: an approach providing a microscopic description of interatomic interactions in alloys. Our simulations show a crossover from a nucleated growth regime to a region where the ordering does not follow any simple growth law

Servet Martinez, Dimitri Petritis

We consider a directed random walk making either 0 or $+1$ moves and a Brownian bridge, independent of the walk, conditioned to arrive at point $b$ on time $T$. The Hamiltonian is defined as the sum of the square of increments of the bridge between the moments of jump of the random walk and interpreted as an energy function over the bridge connfiguration; th

Ann Mattsson

We have analyzed the two-dimensional antiferromagnetic Heisenberg model on the triangular lattice using a Schwinger boson mean-field theory. By expanding around a state with local $120^\circ$ order, we obtain, in the limit of infinite spin, results for the excitation spectrum in complete agreement with linear spin wave theory (LSWT). In contrast to LSWT, how

Lian Zheng, H. A. Fertig

The observability of the Hofstadter spectrum generated by a Wigner crystal using photoluminescence techniques is studied. Itinerant hole geometries are examined, in which a hole may combine directly with electrons in the lattice. It is found that when the effect of lattice distortions of the WC due to interactions with the hole are accounted for, only the la

Leon Balents, Matthew P. A. Fisher

We present a general method for determining the phase diagram of systems of a finite number of one dimensional Hubbard--like systems coupled by single--particle hopping with weak interactions. The technique is illustrated by detailed calculations for the two--chain Hubbard model, providing the first controlled results for arbitrary doping and inter-chain hop

Partha Niyogi, Robert C. Berwick

In Phys. Rev. Letters (73:2, 5 Dec. 94), Mantegna et al. conclude on the basis of Zipf rank frequency data that noncoding DNA sequence regions are more like natural languages than coding regions. We argue on the contrary that an empirical fit to Zipf&#39;s ``law&#39;&#39; cannot be used as a criterion for similarity to natural languages. Although DNA is a pr

John McMahon, F. J. Smith

An automatic word classification system has been designed which processes word unigram and bigram frequency statistics extracted from a corpus of natural language utterances. The system implements a binary top-down form of word clustering which employs an average class mutual information metric. Resulting classifications are hierarchical, allowing variable c

Gregory Grefenstette, Simone Teufel

Nominalization is a highly productive phenomena in most languages. The process of nominalization ejects a verb from its syntactic role into a nominal position. The original verb is often replaced by a semantically emptied support verb (e.g., &#34;make a proposal&#34;). The choice of a support verb for a given nominalization is unpredictable, causing a proble

Sabine Schindler

We test the reliability of mass determination in clusters of galaxies by X-ray observations. The true mass in cluster models is compared to the mass derived by the X-ray emission and X-ray temperature of a model assuming hydrostatic equilibrium and spherical symmetry. In general we find good agreement between the X-ray mass and the true mass without any syst

Daniel E. Holz, Robert M. Wald

We analyze the limitations imposed by photon counting statistics on extracting useful information about MACHOs from Earth-based parallax observations of microlensing events. We find that if one or more large (say $2.5\,\rm m$) telescopes are dedicated to observing a MACHO event for several nights near maximum amplification, then it is possible, in principle,

Marek Pawlowski, Ryszard Raczka

The predictions for electroweak observables following from Higgs-Free Model for Fundamental Interactions are derived. It is shown that these predictions are close to the Standard Model predictions and they are in a surprising agreement with the experimental data. The analysis of electroweak observables at low and high energy suggests that the Higgs mass $m_H

Marek Pawlowski, Ryszard Raczka

We show that the local conformal group $C$ is a natural symmetry group of strong, electroweak and gravitational interactions. A model for these interactions invariant under the local symmetry group $G=SU(3)\times SU(2)_{L}\times U(1)\times C$ is postulated. It contains all Standard Model and gravitational fields, however the Higgs mass term $μ^2Φ^{\dagger}Φ$

Edward Farhi, Krishna Rajagopal, Robert Singleton,

We describe classical solutions to the Minkowski space equations of motion of SU(2) gauge theory coupled to a Higgs field in the spatial spherical ansatz. We show how to reduce the equations to four equations for four gauge invariant degrees of freedom which correspond to the massive gauge bosons and the Higgs particle. The solutions typically dissipate at v

Tengiz M. Bibilashvili

The method of the real time perturbative calculations of nonequilibrium averages is generalised to the case of varying chemical potential. Calculations are performed in the frame of Zubarev&#39;s nonequilibrium density matrix approach. In this approach perturbations of temperature and other thermodynamical parameters are taken into account explicitly includi

Christina M. Bird

Although numerous studies of individual galaxy clusters have demonstrated the presence of significant substructure, previous studies of the distribution of masses of galaxy clusters determined from optical observations have failed to explicitly correct for substructure in those systems. In this {\it Letter} I present the distributions of velocity dispersion,

P. Frisch, J. Einasto, M. Einasto, W. Freudling

Recently, the observed cellular nature of the large-scale structure of the Universe with its quasi-regular pattern of superclusters and voids has been pointed out by several authors. In this paper, we investigate properties of the initial power spectrum which lead to prediction of structure consistent with these observations.For this purpose, we analyze the

A. Smilga

Some exact relations for the spectral density $ρ(λ)$ of the Euclidean Dirac operator in $QCD$ are derived. They follow directly from the chiral symmetry of the $QCD$ lagrangian with massless quarks. New results are obtained both in thermodynamic limit when the Euclidean volume $V$ is sent to infinity and also in the theory defined in finite volume where the

Jonathan Halliwell, Andreas Zoupas

We analyse the quantum evolution of a particle moving in a potential in interaction with an environment of harmonic oscillators in a thermal state, using the quantum state diffusion (QSD) picture of Gisin and Percival, in which one associates the usual Markovian master equation for the density operator with a class of stochastic non-linear Schrödinger equati

I. Chuang, Raymond Laflamme, P. Shor, W. Zurek

In a quantum computer any superposition of inputs evolves unitarily into the corresponding superposition of outputs. It has been recently demonstrated that such computers can dramatically speed up the task of finding factors of large numbers -- a problem of great practical significance because of its cryptographic applications. Instead of the nearly exponent

Jiang-Hua Lu

This work is motivated by a result of Drinfeld on Poisson homogeneous spaces. For each Poisson manifold $P$ with a Poisson action by a Poisson Lie group $G$, we describe a Lie algebroid structure on the direct sum vector bundle $P \times {\frak g} \oplus T^*P$, where ${\frak g}$ is the Lie algebra of $G$. It is built out of the transformation Lie algebroid $

J. -P. Eckmann, Th. Gallay, C. E. Wayne

We consider the Ginzburg-Landau equation, $ \partial_t u= \partial_x^2 u + u - u|u|^2 $, with complex amplitude $u(x,t)$. We first analyze the phenomenon of phase slips as a consequence of the {\it local} shape of $u$. We next prove a {\it global} theorem about evolution from an Eckhaus unstable state, all the way to the limiting stable finite state, for per

David R. Harrington

The extent to which information about fluctuations in hadron-nucleon total cross sections in the frozen approximation can be extracted from very high energy hadron-nucleus total cross section measurements for a range of heavy nuclei is discussed. The corrections to the predictions of Glauber theory due to these fluctuations are calculated for several models

K. Varga, Y. Suzuki

A precise variational solution to $N$=2--6-body problems is reported. The trial wave functions are chosen to be combinations of correlated Gaussians, which facilitate a fully analytical calculation of the matrix elements. The nonlinear parameters of the trial function are selected by a stochastic method. Fermionic and bosonic few-body systems are investigate

Martin E. Muldoon, František Neuman

Nonoscillatory second order differential equations always admit ``special&#39;&#39;, principal solutions. For a certain type of oscillatory equation principal pairs of solutions were introduced by Á. Elbert, F. Neuman and J. Vosmanský, {\em Diff. Int. Equations} {\bf 5} (1992), 945--960. In this paper, the notion of principal pair is extended to a wider clas

Haewon Lee

We derive a new algebraic relation which can be used to find various spinor loop anomalies. We show that this relation includes the Wess-Zumino consistency condition. For an example, we consider the chiral anomaly. With this formalism, the consistent anomaly and the covariant anomaly are determined simultaneously.

Geoffrey Dixon

The octonion X-product changes the octonion multiplication table, but does not change the role of the identity. The octonion XY-product is very similar, but shifts the identity as well. This will be of interest to those applying th octonions to string theory.

H. Kawai, N. Tsuda, T. Yukawa

A method to define the complex structure and separate the conformal mode is proposed for a surface constructed by two-dimensional dynamical triangulation. Applications are made for surfaces coupled to matter fields such as $n$ scalar fields ($n=0,1$ and $4$) and $m$ Ising spins ($m=1$ and $3$). We observe a well-defined complex structure for cases when the m

Víctor M. Villalba

In the present article we analyze the problem of a relativistic Dirac electron in the presence of a combination of a Coulomb field, a $1/r$ scalar potential as well as a Dirac magnetic monopole and an Aharonov-Bohm potential. Using the algebraic method of separation of variables, the Dirac equation expressed in the local rotating diagonal gauge is completely

Sergio Albeverio, Shao-Ming Fei

Symmetry properties of stochastic dynamical systems described by stochastic differential equation of Stratonovich type and related conserved quantities are discussed, extending previous results by Misawa. New conserved quantities are given by applying symmetry operators to known conserved quantities. Some detailed examples are presented.

D. V. Boulatov

We show that QCD$_2$ on 2D pseudo-manifolds is consistent with the Gross-Taylor string picture. It allows us to introduce a model describing the one-dimensional evolution of the QCD$_2$ string (in the sense that QCD$_2$ itself is regarded as a zero-dimensional system). The model is shown to possess the third order phase transition associated with the $c=1$ B

Raiko P. Zaikov

The higher spin properties of the non-abelian bosonization in the classical theory are investigated. Both the symmetry transformation algebra and the classical current algebra for the non-abelian free fermionic model are linear Gel&#39;fand-Dickey type algebras. However, for the corresponding WZNW model these algebras are different. There exist symmetry tran

Y. Brihaye, C. Gonera, S. Giller, P. Kosinski

The Galilean invariance in three dimensional space-time is considered. It appears that the Galilei group in 2+1 dimensions posses a three-parameter family of projective representations. Their physical interpretation is discussed in some detail.

Y. Lozano

We construct explicit canonical transformations producing non-abelian duals in principal chiral models with arbitrary group G. Some comments concerning the extension to more general $σ$-models, like WZW models, are given.

Deshpande, Eilam, He, Trampetic

We consider various contributions to the nonresonant decay $B^\pm\rightarrow π^+π^-π^\pm$, both of the long-distance and short-distance types with the former providing for most of the branching ratio, predicted to be $BR(B^\pm\rightarrow π^+π^-π^\pm) = (1.5 - 8.4 )\times 10^{-5}$. We also discuss an application to CP violation resulting from the interference

Thomas Mannel

Recent progress in the theoretical description of inclusive heavy flavour decays is reviewed. After an outline of the theoretical methods applications to total decay rates and semileptonic decay spectra are presented.

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

We use ISAJET to perform a detailed study of the missing transverse energy $\eslt$ plus multi-jet signal expected from superparticle production at the CERN LHC. Our analysis is performed within the framework of the minimal supergravity model with gauge coupling unification and radiative electroweak symmetry breaking. We delineate the region of parameter spac

J. Kwiecinski, A. D. Martin, P. J. Sutton

We solve a unified integral equation to obtain the $x, Q_T$ and $Q$ dependence of the gluon distribution of a proton in the small $x$ regime; where $x$ and $Q_T$ are the longitudinal momentum fraction and the transverse momentum of the gluon probed at a scale $Q$. The equation generates a gluon with a steep $x^{- λ}$ behaviour, with $λ\sim 0.5$, and a $Q_T$

Tzu Chiang Yuan

After a brief review on how heavy quark symmetry constraints the helicity fragmentation probabilities for a heavy quark hadronizes into heavy-light hadrons, we present a heavy quark fragmentation model to extract the value for the Falk-Peskin probability $w_{3/2}$ describing the fragmentation of a heavy quark into a heavy-light meson whose light degrees of f

Gautam Bhattacharyya, John Ellis, K. Sridhar

We consider one-loop corrections to partial widths of the $Z$ induced by supersymmetric Yukawa interactions that violate $R$-parity. The precise experimental values of the leptonic $Z$ partial widths bound these Yukawa couplings, with the most interesting constraints being those on couplings involving the $τ$, since previous constraints on them were very mil

Gautam Bhattacharyya, Debajyoti Choudhury

$D$- and $τ$-decays are used to place bounds on some $R$-parity--violating $λ&#39;$-type Yukawa interactions. Some of these bounds are competitive with the existing ones, some are improved while some are new.

Andrzej J. Buras

We discuss several aspects of rare decays and CP violation in the standard model including the impact of the recent top quark discovery. In particular we review the present status of next-to-leading QCD calculations in this field stressing their importance in the determination of the parameters in the Cabibbo-Kobayashi-Maskawa matrix. We emphasize that the d

R. M. Woloshyn

Chiral symmetry breaking parameters are calculated in quenched SU(2) gauge theory and with Abelian gauge fields projected in maximal Abelian gauge and in field strength gauge. Maximal Abelian gauge projected fields lead to chiral condensate values which are quite similar to those of the full nonabelian theory. Pseudoscalar and vector meson correlators are ca

R. Debbe, S. Gushue, B. Moskowitz, J. Norris

A ring-imaging Čerenkov counter read out by a 100-channel PMT of active area 10$\times$10 cm$^2$ was operated successfully in a test beam at the BNL AGS with several radiator gases, including the heavy fluorocarbon C$_4$F$_{10}$. Ring radii were measured for electrons, muons, pions and kaons over the particle momentum range from 2 to 12 GeV/$c$, and a best r

I. L. Egusquiza

We study the selfadjoint extensions of the spatial part of the D&#39;Alembert operator in a spacetime with two changes of signature. We identify a set of boundary conditions, parametrised by U(2) matrices, which correspond to Dirichlet boundary conditions for the fields, and from which we argue against the suggestion that regions of signature change can isol

Nils Andersson, Kostas D. Kokkotas, Bernard F. Schutz

The oscillation modes of a simple polytropic stellar model are studied. Using a new numerical approach (based on integration for complex coordinates) to the problem for the stellar exterior we have computed the eigenfrequencies of the highly damped w-modes. The results obtained agree well with recent ones of Leins, Nollert and Soffel (1993) Specifically, we

Yoonweon Lee

The purpose of this note is to provide a short cut presentation of a Mayer-Vietoris formula due to Burghelea-Friedlander-Kappeler for the regularized determinant in the case of elliptic operators of Laplace Beltrami type in the form typically needed in applications to torsion.

Joel Feldman, Jacques Magnen, Vincent Rivasseau, Eugene Trubowitz

In these notes we give a very rough sketch of nonperturbative methods of many body quantum field theory that are powerful enough to rigorously control weak coupling instabilities in condensed matter phyics, for example, the Cooper instability in an electron - phonon system.

Yuyao Zha, S. L. Cooper, David Pines

We propose a simple model which accounts for the major features and systematics of experiments on the $c$-axis resistivity, $ρ_c$, for $\lsco$, $\ybco$ and $\bsco $. We argue that the $c$-axis resistivity can be separated into contributions from in-plane dephasing and the $c$-axis ``barrier&#39;&#39; scattering processes, with the low temperature semiconduct

N. K. Wilkin, M. A. Moore

We estimate the energy cost associated with two pancake vortices colliding in a layered superconductor. It is argued that this energy sets the plastics energy scale and is the analogue of the crossing energy for vortices in the continuum case. The starting point of the calculation is the Lawrence-Doniach version of the Ginzburg-Landau free energy for type-II

B. Carazza

We present here a modified hydrodynamical model for the collective electronic excitations of spherical atomic clusters. The model is applied to the giant-dipole plasmon mode of the free fullerene molecule.

Heiko Rieger

In extensive Monte Carlo simulations the phase transition of the random field Ising model in three dimensions is investigated. The values of the critical exponents are determined via finite size scaling. For a Gaussian distribution of the random fields it is found that the correlation length $ξ$ diverges with an exponent $ν=1.1\pm0.2$ at the critical tempera

N. Turner, J. T. Nicholls, K. M. Brown, E. H. Linfield

We have measured the tunneling between two two-dimensional electron gases (2DEGs) in weak magnetic fields, when the carrier densities of the two electron layers are matched. At zero magnetic field, B=0, the lineshape of the equilibrium tunneling resonance is best fit by a Lorentzian, with a linewidth which is determined by the roughness of the tunnel barrier

R. Sugano, T. Onogi, Y. Murayama

We have investigated the effect of thermal fluctuation on the interlayer coupling of three-dimensional Josephson-junction arrays with anisotropic interactions as a model of layered high-$T_c$ oxides, focusing on non-Ohmic current-voltage characteristics. Langevin dynamic simulations were performed for various Josephson-coupling anisotropies and for various t