June 1993 arXiv papers — page 4

A. Makhlin

We calculate the rate of the emission of the photons from the QGP. We base on the real-time kinetic approach [1] without an explicit assumption about a complete thermal equilibrium in the emitting system. ( Figures can be obtained from the author )

A. Makhlin

The rate of emission of heavy dileptons from QGP is found without an assumption of its complete thermal equilibrium. We base on the real-time quantum field kinetic approach [1] and use the expansion up to the second order with respect to strong coupling constant $g$. The final answer is not free from the collinear singularities and we show that this is the a

A. Makhlin

Using the general framework of nonequilibrium statistical mechanics for relativistic quantum field systems we derive the basic equations of quantum field kinetics. The main aim of the approach is calculation of observables associated with quark-gluon plasma which is out of thermal and chemical equilibrium. We show that in the regime of high rate of the phase

V. Barger, K. Cheung, A. Djouadi, B. A. Kniehl

We elaborate on the production of the Standard Model Higgs particle at high-energy $e^+e^-$ colliders through the reaction $e^+e^- \rightarrow ZH$. Particular emphasis is put on the intermediate mass range. In addition to the signal we discuss in detail the background processes. Angular distributions which are sensitive to the spin and parity of the Higgs pa

B. Brahmachari, U. Sarkar, K. Sridhar

We consider an alternative to conventional GUTs originally proposed by Maiani, Parisi and Petronzio, where owing to the existence of extra fermion generations at some intermediate scale, the gauge couplings become large at high energies. We first comment on how the non- supersymmetric version of this scenario is ruled out; we then consider the two-loop evolu

J. Bene, R. Graham

Recent work on $N=2$ supersymmetric Bianchi type IX cosmologies coupled to a scalar field is extended to a general treatment of homogeneous quantum cosmologies with explicitely solvable momentum constraints, i.e. Bianchi types I, II, VII, VIII besides the Bianchi type IX, and special cases, namely the Friedmann universes, the Kantowski-Sachs space, and Taub-

Steven A. Janowsky, Claude A. Laberge

We introduce a model for a sandpile, with N sites, critical height N and each site connected to every other site. It is thus a mean-field model in the spin-glass sense. We find an exact solution for the steady state probability distribution of avalanche sizes, and discuss its asymptotics for large N.

A. S. Rinat, B. K. Jennings

It is argued that the transparency of a medium for passage of a nucleon, knocked-out in a semi-inclusive $(e,e'p)$ reaction and subsequently scattered elastically, is not the same as the one measured in purely elastic scattering. Expressions are given for the properly generalized transparency and those are compared with recently proposed, alternative sug

Costas John Efthimiou, Donald Spector

We use separation of variables as a tool to identify and to analyze exactly soluble time-dependent quantum mechanical potentials. By considering the most general possible time-dependent re-definition of the spatial coordinate, as well as general transformations on the wavefunctions, we show that separation of variables applies and exact solubility occurs onl

A. Sevrin

After reviewing some aspects of gravity in two dimensions, it is shown that non-trivial embeddings of sl(2) in a semi-simple (super) Lie algebra give rise to a very large class of extensions of 2D gravity. The induced action is constructed as a gauged WZW model and an exact expression for the effective action is given. (Talk presented at the Journees Relativ

David Valls-Gabaud

Nearby starburst galaxies have consistently shown anomalous Ly-alpha/H-beta ratios. By re-analysing the published IUE/optical observations, we show that most starbursts present a normal Ly-alpha emission, consistent with case B recombination theory, provided extinction laws appropriate to their metallicities are used. This implies that extinction is more imp

François Lalonde, Dusa McDuff

In this paper we consider a geometric variant of Hofer's symplectic energy, which was first considered by Eliashberg and Hofer in connection with their study of the extent to which the interior of a region in a symplectic manifold determines its boundary. We prove, by a simple geometric argument, that both versions of energy give rise to genuine norms on

Vahid Karimipour

It is shown that the finite dimensional irreducible representations of the quantum matrix algebra $ M_q(n) $ ( the coordinate ring of $ GL_q(n) $ ) exist only when q is a root of unity ( $ q^p = 1 $ ). The dimensions of these representations can only be one of the following values: $ {p^N \over 2^k } $ where $ N = {n(n-1)\over 2 } $ and $ k \in \{ 0, 1, 2, .

T. Moroi, Hitoshi Murayama, T. Yanagida

We assume that strong and electroweak interactions become strong at very high energies. With this assumption, we compute the low-energy gauge coupling constants $α_i (m_Z)$ as a function of the cutoff scale, taking the supersymmetric standard model with $3+2n$ families of quark and lepton multiplets. We find that only the five family case $(n=1)$ is consiste

Claude Bernard, James Labrenz, Amarjit Soni

A lattice calculation of the pseudoscalar decay constant of heavy-light mesons is reported. Results are obtained (in the quenched approximation) from lattices at $β=6.3$ through a procedure that interpolates between the static approximation of Eichten and the conventional ("heavy" Wilson fermion) method. The previously observed discrepancy between th

Ivan Maksymyk, C. P. Burgess, David London

The contribution to precision electroweak measurements due to TeV physics which couples primarily to the $W^\pm$ and $Z$ bosons may be parameterized in terms of the three `oblique correction' parameters, S, T and U. We extend this parameterization to physics at much lower energies, $\ge 100$ GeV, and show that in this more general case three more paramet

Alakabha Datta, Sandip Pakvasa, Utpal Sarkar

We consider higher dimensional operators due to quantum gravity or spontaneous compactification of extra dimensions in Kaluza-Klein type theory and their effect in the $SO(10)$ Lagrangian. These operators change the boundary conditions at the unification scale. As a result one can allow left-right symmetry to survive till very low energy (as low as $\sim$ Te

J. C. Caillon, J. Labarsouque

The ratio $R_T$ of $K^+-^{12}C$ to $K^+-d$ cross sections has been calculated microscopically using a boson-exchange $KN$ amplitude in which the $σ$ and $ω$ mesons are dressed by the modifications of the Dirac sea in nuclear matter. In spite of the fact that this dressing leads to a scaling of the mesons effective mass in nuclear matter, the effect on the $R

Paul S. Green, Tristan Hubsch

In a general superstring vacuum configuration, the `internal' space (sector) varies in spacetime. When this variation is non-trivial only in two space-like dimensions, the vacuum contains static cosmic strings with finite energy per unit length and which is, up to interactions with matter, an easily computed topological invariant. The total spacetime is

E. C. Marino, R. O. Ramos

The method of quantization of magnetic monopoles based on the order-disorder duality existing between the monopole operator and the lagrangian fields is applied to the description of the quantum magnetic monopoles of `t Hooft and Polyakov in the SO(3) Georgi-Glashow model. The commutator of the monopole operator with the magnetic charge is computed explicitl

L. Martina, O. K. Pashaev, G. Soliani

A Chern-Simons gauged Nonlinear Schrödinger Equation is derived from the continuous Heisenberg model in 2+1 dimensions. The corresponding planar magnets can be analyzed whithin the anyon theory. Thus, we show that static magnetic vortices correspond to the self-dual Chern - Simons solitons and are described by the Liouville equation. The related magnetic top

Friedemann Brandt

All anomaly candidates and the form of the most general invariant local action are given for old and new minimal supergravity, including the cases where additional Yang--Mills and chiral matter multiplets are present. Furthermore nonminimal supergravity is discussed. In this case local supersymmetry itself may be anomalous and some of the corresponding anoma

Sergey Fomin, Anatol N. Kirillov

Combinatorial $B_n$-analogues of Schubert polynomials and corresponding symmetric functions are constructed from an exponential solution of the $B_n$-Yang-Baxter equation that involves the nilCoxeter algebra of the hyperoctahedral group.

Boris Blok, Thomas Mannel

We propose a model independent method to determine $|V_{ub}|$ from the energy spectrum of the charged lepton in inclusive semileptonic $B$ decays. The method includes perturbative QCD corrections as well as nonperturbative ones.

Michael I. Eides, Savely G. Karshenboim, Valery A. Shelyuto

Contributions to HFS and to the Lamb shift intervals of order $α^2(Zα)^5$ induced by graphs with two radiative photons inserted in the electron line are considered. It is demonstrated that this last gauge invariant set of diagrams which are capable of producing corrections of considered order consists of nineteen topologically different diagrams. Contributio

Michael J. Dugan, Mitchell Golden

Many years ago Weinberg formulated a definition of ``naturalness'' for effective theories: if an effective theory is to make sense, coefficients must not change too much when the cutoff scale is changed by a factor of order 1. As an example, we consider simple field theories in which an $O(N)$ symmetry spontaneously breaks to $O(N-1)$. We show that i

T. V. Duong, Ernest Ma

We consider a supersymmetric version of the recently proposed SU(3) X U(1) extended gauge model. We show that it is possible to have only two Higgs doublets at the SU(2) X U(1) energy scale but they are not those of the minimal supersymmetric standard model. In particular, the upper bound on the lightest scalar boson of this model is $4 M_Z \sin θ_W$ at tree

G. E. Forden, DZERO Collaboration

We have searched for high Pt (>40 GeV/c) jet events in ppbar collisions at the Fermilab TEVATRON (S**1/2 = 1800 GeV/c2) which have large pseudo-rapidity differences between the jets and are consistent with zero particle production from the underlying event. Preliminary analysis indicates that a significant fraction of these events with "voids" are pr

R. Casalbuoni, S. De Curtis, D. Dominici, P. Chiappetta

Invited talk at the ``Workshop on Physics and Experiments at Linear e+e- Colliders'', Waikoloa, Hawaii, April 26-30, 1993 (presented by D. Dominici)

Matthias Jamin

Results of a recent calculation of the effective $\dS$ Hamiltonian at the next-to-leading order will be presented\footnote{Work done in collaboration with A. J. Buras and M. E. Lautenbacher.}. These, together with an improved treatment of hadronic matrix elements, are used to evaluate the measure for direct CP-violation, $\epe$, at the next-to-leading order.

Andre Krzywicki

We discuss the kinetics of a disoriented chiral condensate, treated as an open quantum system. We suggest that the problem is analogous to that of a damped harmonic oscillator. Master equations are used to establish a hierarchy of relevant time scales. Some phenomenological consequences are briefly outlined.

R. Jakob, P. Kroll

It is demonstrated that any attempt to calculate the perturbative QCD contribution to the pion form factor requires the inclusion of intrinsic transverse momentum besides Sudakov form factors. For momentum transfers of the order of a few GeV the intrinsic transverse momentum leads to a substantial suppression of the perturbative QCD contribution.

Tadashi Kon

We investigate the sparticle production processes $eγ\goto \sele\sz1$ and $γγ\goto \sfermion\overline{\sfermion}$ at high energy $eγ$ and $γγ$ colliders in the framework of the minimal supersymmetric standard model (MSSM). It will be shown that the $eγ$ colliders would be more suitable in searching for the heavy selectrons than $ee$ colliders because of the

C. Kiefer

We address the issue of recovering the time-dependent Schrödinger equation from quantum gravity in a natural way. To reach this aim it is necessary to understand the nonoccurrence of certain superpositions in quantum gravity. We explore various possible explanations and their relation. These are the delocalisation of interference terms through interaction wi

B. W. Murphy, D. F. Chernoff

Some bright cD galaxies in cluster cooling flows have Thomson optical depths exceeding 0.01. A few percent of their luminosity is scattered and appears as diffuse polarized emission. We calculate the scattering process for different geometric combinations of luminosity sources and scattering media. We apply our results to galaxies, with and without active nu

Blane Little, David H. Weinberg

Using cosmological $N$-body simulations and the void probability function (VPF), we investigate the statistical properties of voids within a wide range of initially Gaussian models for the origin of large-scale structure. We pay particular attention to the ability of the VPF to diagnose `biased galaxy formation': the preferential formation of galaxies in

Karl Mannheim

Recent measurements of gamma rays from the powerful quasar 3C273 by the Compton Gamma Ray Observatory show that a powerful cosmic accelerator must be operating. In this paper the evidence for proton acceleration is collected with the result that (i) the gamma ray spectrum should flatten slightly above a few GeV and that (ii) high energy neutrinos from the de

M. Mitchell, J. P. Crutchfield, P. T. Hraber

In this paper we review previous work and present new work concerning the relationship between dynamical systems theory and computation. In particular, we review work by Langton \cite{Langton90} and Packard \cite{Packard88} on the relationship between dynamical behavior and computational capability in cellular automata (CA). We present results from an experi

Mark M. Millonas

A spacially extended model of the collective behavior of a large number of locally acting organisms is proposed in which organisms move probabilistically between local cells in space, but with weights dependent on local morphogenetic substances, or morphogens. The morphogens are in turn are effected by the passage of an organism. The evolution of the morphog

D. T. Son, V. A. Rubakov

Instanton-like transitions (``shadow processes'') are considered in (1+1) dimensional models with one scalar field whose potential is a quadratic well with a cliff. The corresponding classical boundary value problem is solved, and the semiclassical transition probabilities are found in a rather wide range of energies and the numbers of initial partic

Xiao-Gang He

We study contributions to $K_L \rightarrow μ^+μ^-$ from anomalous $WWZ$ interactions. There are, in general, seven anomalous couplings. Among the seven anomalous couplings, only two of them contribute significantly. The others are suppressed by factors like $m_s^2/M_W^2$, $m_d^2$, or $m_K^2/M_W^2$. Using the experimental data on $K_L\rightarrow μ^+μ^-$, we o

J. Piekarewicz

Levinson's theorem for Dirac particles constraints the sum of the phase shifts at threshold by the total number of bound states of the Dirac equation. Recently, a stronger version of Levinson's theorem has been proven in which the value of the positive- and negative-energy phase shifts are separately constrained by the number of bound states of an ap

E. Pace, G. Salme, A. S. Rinat

Using Green$'$s function and operator techniques we give a closed expression for the response of a non-relativistic system interacting through confining, harmonic forces. The expression for the incoherent part permits rapid evaluation of coefficients in a 1/q expansion. A comparison is made with standard approximation methods.

Jamshid Moori

No abstract is available

M. J. Duff, J. X. Lu

We present a generic Lagrangian, in arbitrary spacetime dimension $D$, describing the interaction of a dilaton, a graviton and an antisymmetric tensor of arbitrary rank $d$. For each $D$~and~$d$, we find ``solitonic'' black $\tilde{p}$-brane solutions where $\tilde{p} = \tilde{d} - 1$~and~ $\tilde d = D - d - 2$. These solutions display a spacetime s

D. C. Cabra, E. F. Moreno, C. M. Naón

We study the Abelian Thirring Model when the fermionic fields have non-conserved chiral charge: $Δ{\cal Q}_5 =N$. One of the main features we find for this model is the dependence of the Virasoro central charge on both the Thirring coupling constant and $N$. We show how to evaluate correlation functions and in particular we compute the conformal dimensions f

Mario Bergeron, Gordon Semenoff

We examine the problem of determining which representations of the braid group on a Riemann surface are carried by the wave function of a quantized Abelian Chern-Simons theory interacting with non-dynamical matter. We generalize the quantization of Chern-Simons theory to the case where the coefficient of the Chern-Simons term, $k$, is rational, the Riemann s

J. Bagger, V. Barger, K. Cheung, J. Gunion

In this paper we survey the signals and backgrounds for a strongly-interacting electroweak symmetry breaking sector at hadron supercolliders in the TeV region. We study the process pp->WWX, and compute the rates for the ``gold-plated'' channels, where W^{+/-}->l^{+/-}νand Z -> l^+l^- (l = e,μ), for a wide variety of models. Using a forward jet-tag, a

O. Korakianitis, N. D. Tracas

We evaluate the SUSY and top threshold effects in the context of the MSSM and the string derived model based on SU(4)$\times$SU(2)$_L\times$SU(2)$_R$. In both cases we run the two loop RGEs and determine the lower bounds of the supersymmetric particle masses, dictated by the experimentally accepted regions of the values of the low energy parameters.

M. Gasperini, M. Giovannini, G. Veneziano

We consider the stimulated emission of gravitons from an initial state of thermal equilibrium, under the action of the cosmic gravitational background field. We find that the low-energy graviton spectrum is enhanced if compared with spontaneous creation from the vacuum; as a consequence, the scale of inflation must be lowered, in order not to exceed the obse

C. O. Lousto

We show that black holes fulfill the scaling laws arising in critical transitions. In particular, we find that in the transition from negative to positive values the heat capacities $C_{JQ}$, $C_{ΩQ}$ and $C_{JΦ}$ give rise to critical exponents satisfying the scaling laws. The three transitions have the same critical exponents as predicted by the universali

Lisa M. Lust, Oriol T. Valls, Chandan Dasgupta

We conduct a numerical study of the dynamic behavior of a dense hard sphere fluid by deriving and integrating a set of Langevin equations. The statics of the system is described by a free energy functional of the Ramakrishnan-Yussouff form. We find that the system exhibits glassy behavior as evidenced through stretched exponential decay and two-stage relaxat

Didier Poilblanc

Exact diagonalizations of two dimensional small t--J clusters reveal dominant hole-hole correlations at distance $\sqrt{2}$ (ie between holes on next nearest neighbor sites). A new form of singlet $d_{x^2-y^2}$ pair operator is proposed to account for the spatial extention of the two hole-bound pair beyond nearest neighbor sites.

Onuttom Narayan, B. Sriram Shastry

We establish a correspondence between the evolution of the distribution of eigenvalues of a $N\times N$ matrix subject to a random Gaussian perturbing matrix, and a Fokker-Planck equation postulated by Dyson. Within this model, we prove the equivalence conjectured by Altshuler et al between the space-time correlations of the Sutherland-Calogero-Moser system

Mark M. Millonas

Some intriging connections between the properties of nonlinear noise driven systems and the nonlinear dynamics of a particular set of Hamilton's equation are discussed. A large class of Fokker-Planck Equations, like the Schrödinger equation, can exhibit a transition in their spectral statistics as a coupling parameter is varied. This transition is connec

Ben Moore

If massive black holes constitute the dark matter in the halo surrounding the Milky Way, the existence of low mass globular clusters in the halo suggests an upper limit to their mass, $M_{_{BH}}$. We use a combination of the impulse approximation and numerical simulations to constrain $M_{_{BH}} \lsim 10^3M_\odot$, otherwise several of the halo globular clus

Mark M. Millonas

A class of models with applications to swarm behavior as well as many other types of spatially extended complex biological and physical systems is studied. Internal fluctuations can play an active role in the organization of the phase structure of such systems. Consequently, it is not possible to fully understand the behavior of these systems without explici

C. P. Burgess, Oscar Hernandez

We make a number of small changes, including correcting an error in our heavy-neutrino decay rate. None of our analysis is changed, either in substance or detail.

Rodney Price, Xuejun Zhu, P. M. Platzman

We compare the free energy computed from the ground state energy and low-lying excitations of the 2-D Wigner solid and the fractional quantum Hall liquid, at magnetic filling factors $ν= 1/7$ and 1/9. We find that the Wigner solid melts into the fractional quantum Hall liquid at roughly the same temperature as that of some recent luminescence experiments, wh

M. Cadoni

We prove, using arguments relying only on the "special Kähler" structure of the moduli space of the Calabi-Yau three-fold, that in the case of one single modulus the quantum modular group of the string effective action corresponding to Calabi-Yau vacua can not be SL(2,${Z\kern -4.6pt Z}$).

Albrecht Hess, Gilles Pisier

Let $(M,μ)$ and $(N,ν)$ be measure spaces. In this paper, we study the $K_t$--\,functional for the couple $$A_0=L^\infty(dμ\,; L^1(dν))\,,~~A_1=L^\infty(dν\,; L^1(dμ))\,. $$ Here, and in what follows the vector valued $L^p$--\,spaces $L^p(dμ\,; L^q(dν))$ are meant in Bochner's sense. One of our main results is the following, which can be viewed as a refi

Alexander Koldobsky

Let $E$ be one of the spaces $C(K)$ and $L_1$, $F$ be an arbitrary Banach space, $p>1,$ and $(X,σ)$ be a space with a finite measure. We prove that $E$ is isometric to a subspace of the Lebesgue-Bochner space $L_p(X;F)$ only if $E$ is isometric to a subspace of $F.$ Moreover, every isometry $T$ from $E$ into $L_p(X;F)$ has the form $Te(x)=h(x)U(x)e, e\in E,$

S. R. Aladim, M. J. Martins

We discuss a class of transfer matrix built by a particular combination of isomorphic and non-isomorphic GL(N) invariant vertex operators. We construct a conformally invariant magnet co nstituted of an alternating mixture of GL(N) ``spins'' operators at different order of represent ation. The corresponding central charge is calculated by analysing th

Sergio Ferrara, Massimo Porrati

We consider open strings in an external constant magnetic field $H$. For an (infinite) sequence of critical values of $H$ an increasing number of (highest spin component) states lying on the first Regge trajectory becomes tachyonic. In the limit of infinite $H$ all these states are tachyons (with a common tachyonic mass) both in the case of the bosonic strin

A. L. Larsen

We comment on some calculations concerning the finite-thickness corrections to the (generalized) Nambu action for a curved domain wall in Minkowski space. Contrary to a recent claim in the literature, we find no first order corrections in the wall-thickness, and only one second order correction proportional to the Ricci curvature of the wall. These results a

R. S. Fletcher, T. Stelzer

We examine the structure of the underlying event in neutral Higgs production at the Superconducting-Supercollider (SSC). Gaps, regions of rapidity containing no soft particle production, can provide a clean signature for $W$ boson fusion to the heavy Higgs. We first examine the physical basis of gap production and estimate the survival probability of gaps in

J. Bernabeu, E. Nardi, D. Tommasini

Together with the existence of new neutral gauge bosons, models based on extended gauge groups (rank $> 4$) often predict also new charged fermions. A mixing of the known fermions with new states with {\it exotic} weak-isospin assignments (left-handed singlets and right-handed doublets) will induce tree level flavour changing neutral interactions mediated by

S. Y. Choi, J. S. Shim, H. S. Song

Gravitational Compton scattering process with a massive fermion is studied in the context of the linearized gravity. Gravitational gauge invariance and graviton transversality cause the transition amplitude to be factorized into that of scalar QED Compton scattering and that of fermion QED Compton scattering with an overall kinematical factor. The factorizat

A. E. Kaloshin, V. M. Persikov

We analyze the CELLO angular distributions $γγ\rightarrowπ^+π^-$ with the unitary model \cite{KS-86} for helicity 2 amplitude. In contrast to previous analysis \cite{CELLO} we do not see any QED damping. The obtained S--wave does not contradict to low--energy theorem and demonstrates more clealy the resonance--like behaviour near 1.3 Gev.

H. Baer, C. Kao, X. Tata

Within the supergravity framework, sleptons are expected to be considerably lighter than squarks if gluinos and squarks are approximately degenerate. This can lead to a significant enhancement in leptonic branching ratio for neutralinos, and sometimes, charginos. Using ISAJET 7.0/ISASUSY 1.0, we evaluate the multilepton signals from cascade decays of gluinos

S. R. Aladim, M. J. Martins

We discuss a class of transfer matrix built by a particular combination of isomorphic and non-isomorphic GL(N) invariant vertex operators. We construct a conformally invariant magnet constituted of an alternating mixture of GL(N) ``spins'' operators at different order of representation. The corresponding central charge is calculated by analysing the

Andrei Talapov, Vladimir Dotsenko

High accuracy Monte Carlo simulation results for 1024*1024 Ising system with ferromagnetic impurity bonds are presented. Spin-spin correlation function at a critical point is found to be numerically very close to that of a pure system. This is not trivial since a critical temperature for the system with impurities is almost two times lower than pure Ising $T

Jian Ping Lu

Mott-Hubbard metal-insulator transitions in $N$-fold degenerate Hubbard models are studied within the Gutzwiller approximation. For any rational filling with $x$ (integer) electrons per site it is found that metal-insulator transition occurs at a critical correlation energy $U_c(N,x)=U_c(N,2N-x)=γ(N,x)|\barε(N,x)|$, where $\barε$ is the band energy per parti

Song He, P. M. Platzman, B. I. Halperin

We investigate the properties of the one-electron Green's function in an interacting two-dimensional electron system in a strong magnetic field, which describes an electron tunneling into such a system. From finite-size diagonalization, we find that its spectral weight is suppressed near zero energy, reaches a maximum at an energy of about $0.2e^{2}/εl_{

Ping Ao, Qian Niu, David J. Thouless

Based on ideas of off-diagonal long range order and two-fluid model, we demonstrate that adiabatic phases for a slow motion of a vortex in a superconductor film give rise naturally to the Magnus force at finite temperatures.

Troy Shinbrot

Synchronization among globally coupled, chaotic map lattices can be related to stable periodic windows in isolated chaotic maps. This relation provides a simple predictive tool for the understanding of complicated behavior in coupled physical, chemical and biological systems.

Giovanni Gallavotti

A selfcontained proof of the KAM theorem in the Thirring model is discussed.

Aaron Bertram, Georgios Daskalopoulos, Richard Wentworth

Two compactifications of the space of holomorphic maps of fixed degree from a compact Riemann surface to a Grassmannian are studied. It is shown that the Uhlenbeck compactification has the structure of a projective scheme and is dominated by the algebraic compactification arising as a Grothendieck Quot scheme. The latter may be embedded into the moduli space

Valeri V. Dvoeglazov, Sergei V. Khudyakov

The composite system, formed by two $S=1$ particles, is considered. The field operators of constituents are transformed on the $(1,0)\oplus (0,1)$ representation of the Lorentz group. The problem of interaction of $S=1$ particle with the electromagnetic field is also discussed.

N. J. Cornish, N. E. Frankel

We investigate rotation and rotating structures in (2+1)-dimensional Einstein gravity. We show that rotation generally leads to pathological physical situations.

I. Vattulainen, K. Kankaala, J. Saarinen, T. Ala-Nissila

We present results of extensive statistical and bit level tests on three implementations of a pseudorandom number generator algorithm using the lagged Fibonacci method with an occasional addition of an extra bit. First implementation is the RCARRY generator of James, which uses subtraction. The second is a modified version of it, where a suggested error pres

A. N. Ivanov, N. I. Troitskaya, M. Faber, M. Schaler

We show that at the leading order in the large-$N$ expansion a lattice QCD motivated linear rising confinement potential at large distances leads to a non-local four-quark interaction that realizes spontaneous breaking of chiral symmetry (SBCS) in the same way the Nambu-Jona-Lasinio model does. The dynamical quark mass $m$, which represents the solution of t

T. Onogi, Y. Murayama

Quantum Monte Carlo simulations are used to investigate the two-dimensional superfluid properties of the hard-core boson model, which show a strong dependence on particle density and disorder. We obtain further evidence that a half-filled clean system becomes superfluid via a finite temperature Kosterlitz-Thouless transition. The relationship between low tem

Sadhan K. Adhikari, Lauro Tomio, T. Frederico

We derive a set of relativistic three-particle scattering equations in the three-particle c.m. frame employing a relativistic three-particle propagator suggested long ago by Ahmadzadeh and Tjon in the c.m. frame of a two-particle subsystem. We make the coordinate transformation of this propagator from the c.m. frame of the two-particle subsystem to the three

Daniel S. Freed

In this note, based on a conference talk, we show how a 3 dimensional topological field theory leads to an algebraic gadget roughly equivalent to a quantum group. This is an expository version of some material in hep-th/9212115 (where we also carry out computations for a specific finite example). We also explain how to incorporate the central extensions usua

A. Koubek, G. Mussardo

We classify the operator content of local hermitian scalar operators in the Sinh-Gordon model by means of independent solutions of the form-factor bootstrap equations. The corresponding linear space is organized into a tower-like structure of dimension $n$ for the form factors $F_{2n}$ and $F_{2n-1}$. Analyzing the cluster property of the form factors, a par

Yu. Makeenko

I consider the Hermitean two-matrix model with a logarithmic potential which is associated in the one-matrix case with the Penner model. Using loop equations I find an explicit solution of the model at large N (or in the spherical approximation) and demonstrate that it solves the corresponding Riemann-Hilbert problem. I construct the potential of the Kazakov

S. B. Giddings

A brief review of the confrontation between black hole physics and quantum-mechanical unitarity is presented. Possibile reconciliations are modifying the laws of physics to allow fundamental loss of information, escape of information during the Hawking process, or black hole remnants. Each of these faces serious objections. A better understanding of the prob

Lawrence M. Krauss

The COBE results, to be followed in the near future by other Cosmic Microwave Background measurements, are providing us with a new fundamental tool to probe the formation of large scale structure in the Universe, and in so doing to constrain our models of the early universe and the nature of dark matter. I describe briefly here how to interpret the COBE resu

William A. Ponce, Arnulfo Zepeda, Juan B. Flórez

We proof that the proton is stable in the left-right symmetric gauge model [SU(6)]$^3\times$Z$_3$, which unifies nongravitational forces with flavors, broken spontaneously by a minimal set of Higgs Fields and Vacuum Expectation Values down to SU(3)$_{c}\otimes$U(1)$_{EM}$\hspace{0.2cm} . We also compute the evolution of the gauge coupling constants and show

W. J. Stirling, R. G. Roberts

A slight incompatibility in recent low-energy and high-energy α_s measurements can be interpreted as evidence for new light colour degrees of freedom. Assuming that these are the gluinos of a supersymmetric extension of the Standard Model, we investigate to what extent they change the standard QCD predictions for deep inelastic structure functions, and in pa

P. Cea, L. Cosmai

We analyze SU(2) gauge theory in a constant chromomagnetic field in three dimensions. Our analysis instead of supporting the existence of a non-trivial minimum in the effective potential, corroborates the evidence of the unstable modes on the lattice.

Todd A. Brun

Following the formalism of Gell-Mann and Hartle, phenomenological equations of motion are derived from the decoherence functional formalism of quantum mechanics, using a path-integral description. This is done explicitly for the case of a system interacting with a ``bath'' of harmonic oscillators whose individual motions are neglected. The results ar

Alan D. Rendall

The global properties of spatially homogeneous cosmological models with collisionless matter are studied. It is shown that as long as the mean curvature of the hypersurfaces of homogeneity remains finite no singularity can occur in finite proper time as measured by observers whose worldlines are orthogonal to these hypersurfaces. Strong cosmic censorship is

William Arveson

This is a survey of four recent papers which deal with the relationship of simple C*-algebras to the problem of computing the spectra of self-adjoint operators in the general case, especially when the spectrum is not discrete. It is an expanded version of a talk presented at the 50 year C*-algebra celebration, held at the annual meeting of the AMS in San Ant

G. Dunne

The second-quantized form of the Laughlin states for the fractional quantum Hall effect is discussed by decomposing the Laughlin wavefunctions into the $N$-particle Slater basis. A general formula is given for the expansion coefficients in terms of the characters of the symmetric group, and the expansion coefficients are shown to possess numerous interesting

Randall D. Kamien, Pierre Le Doussal, David R. Nelson

The consequences of rotational invariance in a recent theory of fluctuations in dilute polymer nematics are explored. A correct rotationally invariant free energy insures that anomalous couplings are not generated in a one-loop renormalization group calculation.

Song He, P. M. Platzman, B. I. Halperin

We investigate the properties of the one-electron Green's function in an interacting two-dimensional electron system in a strong magnetic field, which describes an electron tunneling into such a system. From finite-size diagonalization, we find that its spectral weight is suppressed near zero energy, reaches a maximum at an energy of about $0.2e^{2}/εl_{

Andreas Klümper

The free energy and correlation lengths of the spin-1/2 $XYZ$ chain are studied at finite temperature. We use the quantum transfer matrix approach and derive non-linear integral equations for all eigenvalues. Analytic results are presented for the low-temperature asymptotics, in particular for the critical $XXZ$ chain in an external magnetic field. These res

R. Z. Bariev, A. Klümper, A. Schadschneider, J. Zittartz

We investigate the excitation spectrum of a model of $N$ colour fermions with correlated hopping which can be solved by a nested Bethe ansatz. The gapless excitations of particle-hole type are calculated as well as the spin-wave like excitations which have a gap. Using general predictions of conformal field theory the long distance behaviour of some groundst