July 1994 arXiv papers — page 7

Andrey M. Shirokov

Results of some recent investigations of democratic three-body decays of nuclear systems are discussed. In particular, we consider experimental studies of three-body ($α+N+N$)-decay of $A=6$ nuclei and $J$-matrix calculations of monopole excitations in $^{12}$C and $E1$ transitions in $^{11}$Li in the three-body-continuum cluster models $α+ α+ α$ and $^{9}$L

Kazuhiro Sano, Yoshiaki Ōno

We investigate the one-dimensional(1D) d-p model, simulating a Cu-O linear chain with strong Coulomb repulsion, by using the numerical diagonalization method. Using the Luttinger liquid theory, we obtained phase diagrams of the ground state on $U_d-U_{pd}$ plane, where $U_d$ and $U_{pd}$ represent on-site interaction at d-sites and the nearest-neighbor inter

Andreas Steffens

By using the classification of Fano 3-folds we prove: Let $X$ be Fano 3-fold. Assume that the tangent bundle $T_X$ of $X$ is not stable (i.e. semi-stable or unstable). Then $b_2\geq 2$ and a relative tangent sheaf $T_{X/Y}$ of a contraction $f:X\longrightarrow Y$ of an extremal face on $X$ is a destabilising subsheaf of $T_X$.

Pavel Etingof, Igor Frenkel, Alexander Kirillov

We describe vector valued conjugacy equivariant functions on a group K in two cases -- K is a compact simple Lie group, and K is an affine Lie group. We construct such functions as weighted traces of certain intertwining operators between representations of K. For a compact group $K$, Peter-Weyl theorem implies that all equivariant functions can be written a

N. W. Park, Chaiho Rim, D. S. Soh

We analyze the Chern-Simons field theory coupled to non-relativistic matter field on a sphere using canonical transformation on the fields with special attention to the role of the rotation symmetry: SO(3) invariance restricts the Hilbert space to the one with a definite number of charges and dictates Dirac quantization condition to the Chern-Simons coeffici

A. I. Bochkarev, R. S. Willey

We study the scheme dependence of the two-loop expression for the $\rho$-parameter of the Standard Model in the heavy $t$-quark mass limit $m_{t} \gg m_{w}$. In the $\ms$-scheme the two-loop electroweak correction to the ${\cal O}(m_{t}^{2})$ term in $\dr$ is found greater than the QCD $\as$-correction.

Ruth Durrer, Zhi-hong Zhou

The topic of this letter is structure formation with topological defects. We first present a partially new, fully local and gauge invariant system of perturbation equations to treat microwave background and dark matter fluctuations induced by topological defects (or any other type of seeds). We show that this treatment is extremly well suited for linear nume

V. Topor Pop, A. Andrighetto, M. Morando, F. Pellegrini

In this report we have made a systematic study of strangeness production in proton-proton(pp),proton-nucleus(pA) and nucleus- nucleus(AA) collisions at CERN Super Proton Synchroton energies, using$\,\,\, HIJING\,\,\, MONTE \,\,\,CARLO \,\,\,MODEL $ \\ (version $HIJ.01$). Numerical results for mean multiplicities of neutral strange particles ,as well as their

X. S. Fang, C. M. Ko, G. Q. Li, Y. M. Zheng

The relativistic transport model, in which the nucleon effective mass is connected to the scalar field while its energy is shifted by the vector potential, is extended to include the kaon degree of freedom. We further take into account the medium modification of the kaon mass due to the explicit chiral symmetry breaking. Both the propagation of kaons in the

G. Q. Li, C. M. Ko

Antiproton production in Ni+Ni collisions at 1.85 GeV/nucleon is studied in the relativistic Vlasov-Uehling-Uhlenbeck model. The self-energies of the antiproton are determined from the nucleon self-energies by the G-parity transformation. Also, the final-state interactions of the antiproton including both rescattering and annihilation are explicitly treated.

G. Q. Li, C. M. Ko

Dilepton production from both pion-pion and kaon-antikaon annihilation in heavy-ion collisions is studied using the relativistic transport model. The formation of a rho meson from pion-pion annihilation and a phi meson from kaon-antikaon annihilation, their propagation in the medium, and their decay into dileptons are explicitly treated. Including the medium

S. Drozdz, S. Nishizaki, J. Speth, J. Wambach

The rate of phase-space exploration in the decay of isovector and isoscalar giant quadrupole resonances in $^{40}$Ca is analyzed. The study is based on the time dependence of the survival probability and of the spectrum of generalized entropies evaluated in the space of 1p-1h and 2p-2h states. If the 2p-2h background shows the characteristics typical for cha

Fernando T. Brandt, Josif Frenkel

We examine the behavior of the non-linear interactions between electromagnetic fields at high temperature. It is shown that, in general, the log(T) dependence on the temperature of the Green functions is simply related to their UV behavior at zero-temperature. We argue that the effective action describing the nonlinear thermal electromagnetic interactions ha

M. Kibler

Some consequences of a $qp$-quantization of a point group invariant developed in the enveloping algebra of $SU(2)$ are examined in the present note. A set of open problems concerning such invariants in the $U_{qp}(u(2))$ quantum algebra picture is briefly discussed.

D. Bailin, A. Love, W. A. Sabra, S. Thomas

${\bf Z}_2\times {\bf Z}_2$ Coxeter orbifolds are constructed with the property that some twisted sectors have fixed planes for which the six-torus can not be decomposed into a direct sum ${\bf T}^2\bigoplus{\bf T}^4 $ with the fixed plane lying in ${\bf T}^2$. The string loop threshold corrections to the gauge coupling constants are derived, and display sym

Uwe Grimm, S. Ole Warnaar

In this paper we present representations of the recently introduced dilute Birman-Wenzl-Murakami algebra. These representations, labelled by the level-$l$ B$^{(1)}_n$, C$^{(1)}_n$ and D$^{(1)}_n$ affine Lie algebras, are Baxterized to yield solutions to the Yang-Baxter equation. The thus obtained critical solvable models are RSOS counterparts of the, respect

Jörg Schray

The theory of vectors and spinors in 9+1 dimensional spacetime is introduced in a completely octonionic formalism based on an octonionic representation of the Clifford algebra $\Cl(9,1)$. The general solution of the classical equations of motion of the CBS superparticle is given to all orders of the Grassmann hierarchy. A spinor and a vector are combined int

Ming Lu, Martin J. Savage, Mark B. Wise

Strong interaction $Λπ$ phase shifts relevant for the weak nonleptonic decay $Ξ\rightarrow Λπ$ are calculated using baryon chiral perturbation theory. We find in leading order that the S-wave phase shift vanishes and the $J={1 \over 2}$ P-wave phase shift is $-1.7 ^{\rm o} $. The small phase shifts imply that CP violation in this decay will be difficult to o

X. Zhang, S. K. Lee, K. Whisnant, B. -L. Young

There are theoretical speculations that the top quark may have different properties from that predicted by the standard model. We use an effective Lagrangian technique to model such a non-standard top quark scenario and study its effects on the electroweak baryogenesis, low and high energy physics.

J. Keppler, H. M. Hofmann

The spin structure of the proton is investigated in the framework of an extended quark potential model which in addition to the conventional $3q$--structure also takes into account $(3q)(q\bar q)$--admixtures in the proton wave function. For reasons of parity such admixtures contain an odd orbital angular momentum thus allowing the proton spin to be shared a

Grish C. Joshi, Masahisa Matsuda, Morimitsu Tanimoto

We study the conditions of maximal $CP$ violation in the neutral Higgs mass matrix of the two Higgs doublet model. We get fixed values of $\tan\b$ and constraints on the Higgs potential parameters. Two neutral Higgs scalars are constrained to be lighter than the charged Higgs scalar and these two Higgs scalars are expected to be almost degenerate due to the

T. Bhattacharya, R. Lacaze, A. Morel

We develop an ansatz for expressing the free energy of the two dimensional $q$-states Potts model for $q > 4$ near its first order phase transition point. We notice that for the moderate values of $ q \lesssim 15 $, the energy profile at the phase transition is not expressible as a sum of gaussians. We discuss how this affects the traditional finite size ana

K. Peeters, C. Schweigert, J. W. van Holten

We reconsider space-time singularities in classical Einsteinian general relativity: with the help of several new co-ordinate systems we show that the Schwarzschild solution can be extended beyond the curvature singularity at r=0. The extension appears as an infinite covering of standard Kruskal space-time. While the two-dimensional reduction of this infinite

Dexin Zhong, Daniel ben-Avraham

We study the diffusion-limited process $A+A\to A$ in one dimension, with finite reaction rates. We develop an approximation scheme based on the method of Inter-Particle Distribution Functions (IPDF), which was formerly used for the exact solution of the same process with infinite reaction rate. The approximation becomes exact in the very early time regime (o

P. Tamayo, F. J. Alexander, R. Gupta

We study a class of 2D non-equilibrium Ising models based on competing dynamics induced by contact with heat-baths at two different temperatures. We make a comparative study of the non-equilibrium versions of Metropolis, heat bath/Glauber and Swendsen-Wang dynamics and focus on their critical behavior in order to understand their universality classes. We pre

M. Lassig

One-dimensional massive quantum particles (or 1+1-dimensional random walks) with short-ranged multi-particle interactions are studied by exact renormalization group methods. With repulsive pair forces, such particles are known to scale as free fermions. With finite $m$-body forces (m = 3,4,...), a critical instability is found, indicating the transition to a

M. Buttiker

Electro-static potentials for samples with the topology of a ring and penetrated by an Aharonov-Bohm flux are discussed. The sensitivity of the electron-density distribution to small variations in the flux generates an effective electro-static potential which is itself a periodic function of flux. We investigate a simple model in which the flux sensitive pot

R. G. Dias, J. M. Wheatley

It is demonstrated that the spatial decay of the pair propagator in a Luttinger liquid with spin charge separation contains a logarithmic correction relative to the free fermi gas result in a finite interval between the spin and charge thermal lengths. It is argued that similar effects can be expected in higher dimensional systems with spin charge separation

N. B. Ivanov, J. Richter

We reconsider the results cocerning the extreme-quantum $S=1/2$ square-lattice Heisenberg antiferromagnet with frustrating diagonal couplings ($J_1-J_2$ model) drawn from a comparison with exact-diagonalization data. A combined approach using also some intrinsic features of the self-consistent spin-wave theory leads to the conclusion that the theory strongly

J. Richter, N. B. Ivanov, K. Retzlaff

We present a number of arguments in favor of the suggestion that the Marshall-Peierls sign rule survives the frustration in the square-lattice Heisenberg antiferromagnet with frustrating next-nearest-neighbor (diagonal) bonds ($J_{1}-J_{2}$ model) for relatively large values of the parameter $J_{2}/J_{1}$. Both the spin-wave analysis and the exact-diagonaliz

Vaishali Shah, Dinesh Nehete, D. G. Kanhere

The use of energy functionals based on density as the basic variable is advocated for ab initio molecular dynamics. It is demonstrated that the constraint of positivity of density can be incorporated easily by using square root density for minimization of the energy functional. An ad hoc prescription for including nonlocal pseudopotentials for plane wave bas

W. Miller

The lattice Boltzmann method with enhanced collisions and rest particles is used to calculate the flow in a two-dimensional lid-driven cavity. The abilitity of this method to compute the velocity and the pressure of an incompressible fluid in a geometry with Dirichlet and Neumann boundary conditions is verified by calculating a test-problem where the analyti

A. E. Cho, J. D. Doll, D. L. Freeman

In the present paper we describe relaxation methods for constructing double-ended classical trajectories. We illustrate our approach with an application to a model anharmonic system, the Henon-Heiles problem. Trajectories for this model exhibit a number of interesting energy-time relationships that appear to be of general use in characterizing the dynamics.

M. Gasperini

It is stressed that the kinematical problems of the standard cosmological model can be solved by a phase of accelerated contraction of the cosmic scale factor. Such a behaviour is only a particular case of a more general ``pre-big-bang" inflationary scenario, arising naturally in a string cosmology context, and driven asymptotically by the free dilaton f

T. Schramm, R. Kayser

Clusters of galaxies acting as gravitational lenses deform the images of background galaxies. For small galaxies the deformation is determined by the local properties of the lens (shear, convergence). Small circular shaped galaxies are seen as small ellipses. The orientation and axial ratio of the ellipses could then be used to trace the properties of the le

J. Bolz, R. Jakob, P. Kroll, M. Bergmann

Two recently proposed concepts to improve the perturbative calculation of exclusive amplitudes, gluonic radiative corrections (Sudakov factor) and confinement size effects (intrinsic transverse momentum) are combined to study the neutron magnetic form factor in the space-like region. We find that nucleon distribution amplitudes modelled on the basis of curre

A. A. Balinsky, Yu. Burman

Quadratic Poisson brackets on a vector space equipped with a bilinear multiplication are studied. A notion of a bracket compatible with the multiplication is introduced and an effective criterion of such compatibility is given. Among compatible brackets, a subclass of coboundary brackets is described, and such brackets are enumerated in a number of examples.

David Seibert, George Fai

We estimate freezeout conditions for $s$, $c$, and $b$ quarks in high energy nuclear collisions. Freezeout is due either to loss of thermal contact, or to particles ``wandering'' out of the region of hot matter. We then develop a thermal recombination model in which both single-particle (quark and antiquark) and two-particle (quark-antiquark) densiti

S. Weber, M. Kachelriess, M. Unkelbach, H. M. Hofmann

Longitudinal and transverse form factors are calculated for the transition into the low lying excited T=0 and T=1 states of 6Li in the framework of the resonating group model. All form factors are reproduced simultaneously using three cluster-wavefunctions. Meson exchange currents yield only minor corrections and do not lead to any specific structures at lar

C. Zachos, T. Curtright

This is a synopsis and extension of Phys.~Rev.~{\em D49} 5408 (1994). The Pseudodual Chiral Model illustrates 2-dimensional field theories which possess an infinite number of conservation laws but also allow particle production, at variance with naive expectations---a folk theorem of integrable models. We monitor the symmetries of the pseudodual model, both

O. Ragnisco

The integrability of two symplectic maps, that can be considered as discrete-time analogs of the Garnier and Neumann systems is established in the framework of the $r$-matrix approach, starting from their Lax representation. In contrast with the continuous case, the $r$-matrix for such discrete systems turns out to be of dynamical type; remarkably, the induc

Matthias Blau, George Thompson

We analyze in detail the equivariant supersymmetry of the $G/G$ model. In spite of the fact that this supersymmetry does not model the infinitesimal action of the group of gauge transformations, localization can be established by standard arguments. The theory localizes onto reducible connections and a careful evaluation of the fixed point contributions lead

A. G. Litvak, V. A. Mironov, A. P. Protogenov

We discuss the possibility to suppress the collapse in the nonlinear 2+1 D Schrödinger equation by using the gauge theory of strong phase correlations. It is shown that invariance relative to $q$-deformed Hopf algebra with deformation parameter $q$ being the fourth root of unity makes the values of the Chern-Simons term coefficient, $k=2$, and of the couplin

K. Behrndt, T. T. Burwick

In this paper we investigate the vanishing of cosmological singularities by quantization. Starting from a 5d Kaluza--Klein approach we quantize, as a first step, the non--spherical metric part and the dilaton field. These fields which are classically singular become smooth after quantization. In addition, we argue that the incorporation of non perturbative q

J. Rosner

If CP violation in the decays of neutral kaons is due to phases in the weak couplings of quarks, as encoded in the Cabibbo-Kobayashi-Maskawa (CKM) matrix, there are many other experimental consequences. Notable among these are CP-violating rate asymmetries and triangle relations among decay rates in $B$ meson decays, while charmed particle decays should not

J. Rosner

A number of ways are reviewed in which the study of charmed particles can answer corresponding questions about particles containing $b$ quarks. Topics include the properties of resonances, the magnitude of decay constants, the size of spin-dependent effects, and the hierarchy of lifetime differences.

M. Drees

The minimal grand unified supergravity model is discussed. Requiring radiative breaking of the electroweak gauge symmetry, the unification of b and tau Yukawa couplings, a sufficiently stable nucleon, and not too large a relic density of neutralinos produced in the Big Bang constrains the parameter space significantly. In particular, the soft breaking parame

R. D. Amado, Ian I. Kogan

We consider the quantum state describing theDisoriented Chiral Condensate (DCC), which may be produced in high energy collisions. We show how a mean field treatment of the quantum equations corresponding to the classical linear sigma model leads to a squeezed state description of the pions emerging from the DCC. We examine various squeezed and coherent state

D. Matalliotakis, H. P. Nilles

Most discussions of supersymmetric grand unified theories assume universality of the soft supersymmetry breaking terms at the grand scale. We point out that the behaviour of these theories might change significantly in the presence of non--universal soft terms. Particularly in SO(10)--like models with a large value of tan$β$ we observe a decisive change of p

T. Altherr

The general behaviour of perturbation series in non-equilibrium scalar field theory is analysed in some detail, with a particular emphasis on the ``pathological terms'', generated by multiple products of $δ$-functions. Using an intuitive regularization method, it is shown that these terms give large contributions at all orders, even when considering

Lisa Randall, Scott Thomas

Many models of supersymmetry breaking involve particles with weak scale mass and Planck mass suppressed couplings. Coherent production of such particles in the early universe destroys the successful predictions of nucleosynthesis. We show that this problem may be solved by a brief period of weak scale inflation. Furthermore the inflaton potential for such an

A. I. L'vov, A. I. Milstein

Elastic scattering of photons in a Lorentz-scalar potential via virtual spin-zero particle-antiparticle pairs (`` Delbrück scattering") is considered. An analytic expression for the Delbrück amplitude is found exactly in case of an oscillator potential. General properties of the amplitude and its asymptotics are discussed.

L. Bates, E. Lerman

Let $(M,ω)$ be a Hamiltonian $G$-space with a momentum map $F:M \to {\frak g}^*$. It is well-known that if $α$ is a regular value of $F$ and $G$ acts freely and properly on the level set $F^{-1}(G\cdot α)$, then the reduced space $M_α:=F^{-1}(G\cdot α)/G$ is a symplectic manifold. We show that if the regularity assumptions are dropped the space $M_α$ is a un

Adriana Moreo, Daniel Duffy

The electronic momentum distribution ${\rm n({\bf k})}$ of the two dimensional Hubbard model is studied for different values of the coupling ${\rm U/t}$, electronic density ${\rm \langle n \rangle}$, and temperature, using quantum Monte Carlo techniques. A detailed analysis of the data on $8\times 8$ clusters shows that features consistent with hole pockets

Arunava Chakrabarti, S. N. Karmakar, R. K. Moitra

We present a detailed analysis of the nature of electronic eigenfunctions in one-dimensional quasi-periodic chains based on a clustering idea recently introduced by us [Sil et al., Phys. Rev. {\bf B 48}, 4192 (1993) ], within the framework of the real-space renormalization group approach. It is shown that even in the absence of translational invariance, exte

A. P. Protogenov, Yu. V. Rostovtsev, V. A. Verbus

We consider the temporal evolution of strong correlated degrees of freedom in $2+1$~$D$ spin systems using the Wilson operator eigenvalues as variables. It is shown that the quantum-group diffusion equation at deformation parameter $q$ being the $k$-th root of unity has the polynomial solution of degree $k$.

K. Kusakabe, H. Aoki

A numerical scaling analysis is used to show that Nagaoka's ferromagnetic state in two-dimensional Hubbard model with one hole is supersede by an antiferromagnetic (AF) state with a discontinuous jump in the total spin due to the AF coupling as the Hubbard $U$ is made finite. The same applies to the two-hole system, which has a spiral spin structure. We

G. J. Chaitin

This is a revised version of the course notes handed to each participant at the limits of mathematics short course, Orono, Maine, June 1994.

Kunihiko Kaneko

Fluctuations of the mean field of a globally coupled dynamical systems are discussed. The origin of hidden coherence is related with the instability of the fixed point solution of the self-consistent Perron-Frobenius equation. Collective dynamics in globally coupled tent maps are re-examined, both with the help of direct simulation and the Perron-Frobenius e

Joseph Silk

In the first two of these lectures, I present the evidence for baryonic dark matter and describe possible forms that it may take. The final lecture discusses formation of baryonic dark matter, and sets the cosmological context.

Ben Moore, Joseph Silk

If the halo dark matter consists of faint baryonic stars, then these objects probably formed at an early epoch within large associations with similar dynamical properties to globular or open clusters. We use the luminosity function of globular clusters as a function of galactocentric distance to provide a very strong constraint on the properties of RAMBOs. W

E. Brocato, V. Castellani, V. Ripepi

We present a CCD investigation of the galactic globular M5 aimed to increase the statistical relevance of the available sample of evolving bright stars. Previous investigations, limited to the outer cluster region, have been extended toward the cluster center, more than doubling the number of observed luminous stars. On this basis, we discuss a statistically

Edward W Kolb, Mark Abney, Edmund J Copeland, Andrew R Liddle

A review is presented of recent work by the authors concerning the use of large scale structure and microwave background anisotropy data to determine the potential of the inflaton field. The importance of a detection of the stochastic gravitational wave background is emphasised, and some preliminary new results of tests of the method on simulated data sets w

H. Sponholz, D. Molteni

Results of numerical simulations of shock solutions in a geometrical thin accretion disk around a Kerr black hole (BH) are presented. Using the smoothed particle hydrodynamics (SPH) technique, the influence of the central object is included by means of an effective potential, We first present the theory of standing shock formation in accretion disks around a

Dimitar D. Sasselov, Dalia Goldwirth

We re-examine the systematic errors in the determination of the primordial helium abundance, $Y_{\rm P}$. We find that the systematics are significantly larger than the statistical errors. The uncertainty in (the determination of) $Y_{\rm P}$, is thus, larger than is currently claimed. Furthermore, most of the systematics lead to underestimate of $Y_{\rm P}$

Kunihiko Kaneko, Ichiro Tsuda

Basic problems of complex systems are outlined with an emphasis on irreducibility and dynamic many-to-many correspondences. We discuss the importance of a constructive approach to artificial reality and the significance of an internal observer.

Y. Shtanov, J. Traschen, R. Brandenberger

We study the problem of scalar particle production after inflation by a rapidly oscillating inflaton field. We use the framework of the chaotic inflation scenario with quartic and quadratic inflaton potentials. Particular attention is paid to parametric resonance phenomena which take place in the presence of the quickly oscillating inflaton field. We have fo

Alexander Verbovetsky

This paper provides a description of an algebraic setting for the Lagrangian formalism over graded algebras and is intended as the necessary first step towards the noncommutative C-spectral sequence (variational bicomplex). A noncommutative version of integration procedure, the notion of adjoint operator, Green's formula, the relation between integral an

S. Sorella

A long-wavelength, low energy hamiltonian is derived to describe the dynamic of a single hole in a quantum antiferromagnet in two or higher spatial dimensions. In this {\em exactly solvable} limit a {\em new} kind of symmetry is important to classify the elementary spin excitations of a single hole in the $t-J$ model. This symmetry is hidden at finite size o

Al. Kavalov

We consider a two matrix model with gaussian interaction involving the term $tr ABAB$, which is quartic in angular variables. It describes a vertex model (in particular case - of F-model type) on the lattice of fluctuating geometry and is the simplest representative of the class of matrix models describing coupling to two-dimensional gravity of general verte

Werner Krauth, Marc Mezard

We study the Metropolis dynamics of a simple spin system without disorder, which exhibits glassy dynamics at low temperatures. We use an implementation of the algorithm of Bortz, Kalos and Lebowitz \cite{bortz}. This method turns out to be very efficient for the study of glassy systems, which get trapped in local minima on many different time scales. We find

John David Crawford

An amplitude equation for an unstable mode in a collisionless plasma is derived from the dynamics on the two-dimensional unstable manifold of the equilibrium. The mode amplitude $ρ(t)$ decouples from the phase due to the spatial homogeneity of the equilibrium, and the resulting one-dimensional dynamics is analyzed using an expansion in $ρ$. As the linear gro

H. C. Doenges, M. Schaefer, U. Mosel

A microscopic model of the electromagnetic form factor of the nucleon is developed in a hadronic framework, including pions, nucleons and the Delta-resonance explicitly. The space like on-shell form factors are reproduced and predictions for the half off-shell dependence are made. The impact of this off-shell dependence in the time like sector (q^2 < 1 GeV^2

Yu. A. Lurie, A. M. Shirokov, Yu. F. Smirnov

Properties of the neutron rich $^{11}$Li nucleus are calculated in the framework of the cluster model $^{9}$Li $+n+n$. The formalism of the harmonic oscillator representation of the scattering theory is used for the description of bound and continuum spectrum states in the three-body-democratic-decay approximation. It is shown that this approach allows one t

L. A. Dickey

An explanation for the so-called constrained hierarhies is presented by linking them with the symmetries of the KP hierarchy. While the existence of ordinary symmetries (belonging to the hierarchy) allows one to reduce the KP hierarchy to the KdV hierarchies, the existence of additional symmetries allows to reduce KP to the constrained KP.

Fernando T. Brandt, Josif Frenkel, John C. Taylor

The electron-positron `box&#39; diagram produces an effective action which is fourth order in the electromagnetic field. We examine the behaviour of this effective action at high-temperature (in analytically continued imaginary-time thermal perturbation theory). We argue that there is a finite, nonzero limit as $T\rightarrow \infty$ (where $T$ is the tempera

I. Bengtsson, J. Hallin

The kinematics of SL(2,R) Yang-Mills theory on a circle is considered, for reasons that are spelled out. The gauge transformations exhibit hyperbolic fixed points, and this results in a physical configuration space with a non-Hausdorff &#34;network&#34; topology. The ambiguity encountered in canonical quantization is then much more pronounced than in the com

Phillial Oh, Myung-Ho Kim

We construct the action-angle variables of a classical integrable model defined on complex projective phase space and calculate the quantum mechanical propagator in the coherent state path integral representation using the stationary phase approximation. We show that the resulting expression for the propagator coincides with the exact propagator which was ob

Joseph Polchinski

We investigate the possibility that stringy nonperturbative effects appear as holes in the world-sheet. We focus on the case of Dirichlet string theory, which we argue should be formulated differently than in previous work, and we find that the effects of boundaries are naturally weighted by $e^{-O(1/g_{\rm st})}$.

B. Holdom

We describe a dynamical scheme by which isospin breaking feeds strongly into the $t$ and $b$ masses and not into the $W$ and $Z$ masses. The third family feels a new gauge interaction broken close to a TeV.

I. I. Bigi

The Standard Model contains a natural source for CP asymmetries in weak decays, which is described by the KM mechanism. Beyond $ε_K$ it generates only elusive manifestations of CP violation in {\em light-}quark systems. On the other hand it naturally leads to large asymmetries in certain non-leptonic beauty decays. In particular when $B^0-\bar B^0$ oscillati

I. I. Bigi

After re-stating why beauty physics is so special and sketching its present status I attempt to map out an itinerary for the next fifteen years. The basic elements are listed for a research program that allows to define and probe the KM unitarity triangle in a manner where the numerical uncertainties are reduced to the few percent level. Dedicated experiment

Ph. de Forcrand, A. Krasnitz, R. Potting

We study the Chern-Simons number diffusion rate in the (1+1)-dimensional latticeAbelian Higgs model at temperatures much higher than, as well as comparable to, the sphaleron energy. It is found that in the high-temperature limit the rate is likely to grow as power 2/3 of the temperature. In the intermediate-temperature regime, our numerical simulations show

G. Ecker

After a brief survey of effective field theories, the linear sigma model is discussed as a prototype of an effective field theory of the standard model below the chiral-symmetry-breaking scale. Although it can serve as a toy model for the pion-nucleon interaction, the linear sigma model is not a realistic alternative to chiral perturbation theory. The heavy-

Riccardo Barbieri, Gia Dvali, Alessandro Strumia

We describe a supersymmetric Grand Unified Theory based on the gauge group $\SU(5)^3$, or $\SO(10)^3$, invariant under the interchange of any~SU(5), or~SO(10), with each family multiplet transforming non trivially under one different individual group factor. A realistic pattern of fermion masses and mixings is obtained as a result of an appropriate choice ou

Dmitri Diakonov, Maxim Polyakov, Pavel Pobylitsa, Peter Sieber

The baryon number dissipation rate due to sphaleron transitions at high temperatures in the minimal standard model is evaluated. We find that this rate can be considerably suppressed by one loop contributions of bosonic and fermionic fluctuations which are particularly important for a small mass of the Higgs boson and a large top quark mass. Fixing the latte

M. V. Chizhov

The minimal standard electroweak model yields approximately half the observed value of the $K_L$-$K_S$ mass difference. Antisymmetric tensor fields incorporated into the standard model can provide the rest $0.5\times(Δm_{LS})_{\exp}$. The effective lepton--lepton, quark--lepton and quark--quark tensor interactions induced by the charged tensor particles are

M. V. Chizhov

The most general form of the hamiltonian for the muon decay is presented. We assume that it arises as a result of the exchange of intermediate bosons with a momentum $q$ and naturally should depend on this momentum. That allows us to introduce two additional coupling constants for the tensor interactions which give rise to new parameters in the energy spectr

J. Fleischer, O. V. Tarasov

Feynman diagrams are calculated by means of their Taylor series expansion in terms of external momenta squared. It is demonstrated in various examples that by the application of conformal mapping and Padé approximants, it is possible to obtain high precision results in the spacelike as well as in the timelike region on the cut. Examples are given for two- an

Dirk Kreimer

It is shown that the two-loop four-point functions are similar in structure to the three-point two-loop functions for all mass cases and topologies. The result is derived by using a rotation to a (+,-,-,+) signature without spoiling analyticity properties.

Bob Jacobsen

The electroweak measurements made at LEP using 1989-1993 data are presented in preliminary form. The agreement with the Standard Model is satisfactory, and allows a combined fit to all available data for the masses of the top quark and standard Higgs boson. The fit yields M_t = 177 +11 -11 +18 -19 GeV/c2, where the second error reflects the uncertainty in th

B. Schwingenheuer

The FNAL experiment E773 has measured the phases Phi_{+-} = (43.35 +- 0.70 +- 0.79) degree and Phi_{00}-Phi_{+-} = (0.67 +- 0.85 +- 1.1) degree of the CP violating parameters eta_{+-} and eta_{00} in the decay of neutral kaons into two charged or neutral pions. These preliminary results test CPT symmetry and show no evidence for a violation. In addition we p

James M. Nester, Roh Suan Tung

We present a new finite action for Einstein gravity in which the Lagrangian is quadratic in the covariant derivative of a spinor field. Via a new spinor-curvature identity, it is related to the standard Einstein-Hilbert Lagrangian by a total differential term. The corresponding Hamiltonian, like the one associated with the Witten positive energy proof is ful

O. Klein, C. de C. Chamon, D. Tang, D. M. Abusch-Magder

The conductance resulting from resonant tunneling through a droplet of $N \sim 30$ electrons is used to measure its chemical potential $μ_N$. Abrupt shifts of $μ_N$ occur at sharply defined values of the magnetic field, at which the state of the droplet changes. These are used to study part of the phase-diagram of the droplet in strong magnetic fields; we fi

Dinko Cule, Yonathan Shapir

We study a 2D lattice model of forward-directed waves in which the integrated intensity for classical waves (or probability for quantum mechanical particles) is conserved. The model describes the time evolution of 1D quantum particle in a time-varying potential and also applies to propagation of electromagnetic waves in two dimensions within the parabolic ap

G. Cristofano, G. Maiella, R. Musto, F. Nicodemi

By using the explicit knowledge of the lowest energy single particle wave functions in the presence of an {\it arbitrary} magnetic field, we extend to the case of a torus Jain&#39;s idea of looking at the FQHE as a manifestation of an integer effect for {\it composite fermions}. We show that this can be realized thanks to a redefinition of the vacuum state t

I. Pagonabarraga, M. Rubi

We have studied the adsorption process of non-Brownian particles on a line incorporating hydrodynamic interactionsa and we have numerically analyzed their effect on typical relevant quantities. We compare our model to the ballistic deposition model (BM) and address the limitations of BM in experimental situations. The results obtained can explain some differ

K. Moon, H. Mori, Kun Yang, S. M. Girvin

At strong magnetic fields double-layer two-dimensional-electron-gas systems can form an unusual broken symmetry state with spontaneous inter-layer phase coherence. In this paper we explore the rich variety of quantum and finite-temperature phase transitions associated with this broken symmetry. We describe the system using a pseudospin language in which the

B. Bernu, P. Lecheminant, C. Lhuillier, L. Pierre

Exact spectra of periodic samples are computed up to $ N=36 $. Evidence of an extensive set of low lying levels, lower than the softest magnons, is exhibited. These low lying quantum states are degenerated in the thermodynamic limit; their symmetries and dynamics as well as their finite-size scaling are strong arguments in favor of Néel order. It is shown th

Koichi Takeda

Machine translation (MT) has recently been formulated in terms of constraint-based knowledge representation and unification theories, but it is becoming more and more evident that it is not possible to design a practical MT system without an adequate method of handling mismatches between semantic representations in the source and target languages. In this pa