September 1993 arXiv papers — page 4

J. M. Aguirregabiria, A. Feinstein, J. Ibanez

We obtain a general exact solution of the Einstein field equations for the anisotropic Bianchi type I universes filled with an exponential-potential scalar field and study their dynamics. It is shown, in agreement with previous studies, that for a wide range of initial conditions the late-time behaviour of the models is that of a power-law inflating FRW univ

M. Hatsuda, S. Yahikozawa, P. Ao, D. J. Thouless

We propose a new Landau-Ginzburg theory for arbitrarily shaped vortex strings in superfluid $^4$He. The theory contains a topological term and directly describes vortex dynamics. We introduce gauge fields in order to remove singularities from the Landau-Ginzburg order parameter of the superfluid, so that two kinds of gauge symmetries appear, making the conti

Terence Hwa, Daniel S. Fisher

A systematic analysis of large scale fluctuations in the low temperature pinned phase of a directed polymer in a random potential is described. These fluctuations come from rare regions with nearly degenerate ``ground states''. The probability distribution of their sizes is found to have a power law tail. The rare regions in the tail dominate much of

J. Boronat, J. Casulleras

By means of a Quadratic Diffusion Monte Carlo method we have performed a comparative analysis between the Aziz potential and a revised version of it. The results demonstrate that the new potential produces a better description of the equation of state for liquid $^4$He. In spite of the improvement in the description of derivative magnitudes of the energy, as

Timothy R. Bedding, Albert A. Zijlstra

We have obtained H$α$ CCD images of 21 compact planetary nebulae in the galactic bulge. All objects are resolved and, after deconvolving the seeing disk, we find diameters of 1--2$''$ with typical uncertainties of 20\%. The values are generally in good agreement with radio measurements but are smaller than older optical measurements. Based on the new

Maximo Banados

Static, spherically symmetric solutions of the field equations for a particular dimensional continuation of general relativity with negative cosmological constant are found. In even dimensions the solution has many similarities with the \Sch\ metric. In odd dimensions, the equations of motion are explicitly anti de-Sitter invariant, and the solution is alike

Fred Cooper, John Dawson, Dawn Meredith, Harvey Shepard

We consider a system in which a classical oscillator is interacting with a purely quantum mechanical oscillator, described by the Lagrangian $ L = \frac{1}{2} \dot{x}^2 + \frac{1}{2} \dot{A}^2 - \frac{1}{2} ( m^2 + e^2 A^2) x^2 \>, $ where $A$ is a classical variable and $x$ is a quantum operator. With $\langle x(t) \rangle = 0$, the relevant variable for th

Enrique Gaztanaga

We estimate J-point galaxy averaged correlation functions $\wbar_J(θ)$ for $J=2,...,9$, in a sample of the APM Galaxy Survey with more than $1.3 \times 10^6$ galaxies and a depth $ \calD \sim 400 \Mpc$. The hierarchical amplitudes $s_J=\wbar_J/\wbar_2^{J-1}$ are roughly constant, up to $J=9$, between $0.5 \Mpc$ and $2 \Mpc$ and decrease slowly for larger sca

Victor H. de la Peña, Stephen J. Montgomery-Smith

In this paper the following result, which allows one to decouple U-Statistics in tail probability, is proved in full generality. Theorem 1. Let $X_i$ be a sequence of independent random variables taking values in a measure space $S$, and let $f_{i_1...i_k}$ be measurable functions from $S^k$ to a Banach space $B$. Let $(X_i^{(j)})$ be independent copies of $

N. Tetradis, C. Wetterich

Resubmitted due to LATEXing problems

M. Yu. Lashkevich

The zoo of two-dimensional conformal models has been supplemented by a series of nonunitary conformal models obtained by cosetting minimal models. Some of them coincide with minimal models, some do not have even Kac spectrum of conformal dimensions.

Joseph Iaia, Henry Warchall

: We establish existence of an infinite family of exponentially-decaying non-radial $C^2$ solutions to the equation $Δu + f(u) = 0$ on $R^2$ for a large class of nonlinearities $f$. These solutions have the form $u(r,θ)=e^{i mθ}w(r)$, where $r$ and $θ$ are polar coordinates, $m$ is an integer, and $w:[0,\infty ) \to R$ is exponentially decreasing far from th

K. Chase, A. Mekjian

A model for the fragmentation of a nucleus is developed. Parallels of the description of this process with other areas are shown which include Feynman's theory of the $λ$ transition in liquid Helium, Bose condensation, and Markov process models used in stochastic networks and polymer physics. These parallels are used to generalize and further develop a p

Victor H. de la Peña, Stephen J. Montgomery-Smith

The authors announce a general tail estimate, called a decoupling inequality, for a symmetrized sum of non-linear $k$-correlations of $n>k$ independent random variables.

Anne Taormina

Two sets of identities between unitary minimal Virasoro characters at levels $m=3,4,5$ are presented and proven. The first identity suggests a connection between the Ising and tricritical Ising models since the $m=3$ Virasoro characters are obtained as bilinears of $m=4$ Virasoro characters. The second identity gives the tricritical Ising model characters as

Demosthenes Ellinas

We review some aspects of the relation between ordinary coherent states and q-deformed generalized coherent states with some of the simplest cases of quantum Lie algebras. In particular, new properties of (q-)coherent states are utilized to provide a path integral formalism allowing to study a modified form of q-classical mechanics, to probe some geometrical

Wen-Jui Huang

A study of diff($S^1$) covariant properties of pseudodifferential operator of integer degree is presented. First, it is shown that the action of diff($S^1$) defines a hamiltonian flow defined by the second Gelfand-Dickey bracket if and only if the pseudodifferential operator transforms covariantly. Secondly, the covariant form of a pseudodifferential operato

H. Kawabe, T. Kobayashi, N. Ohtsubo

We study the construction of the minimal supersymmetric standard model from the $Z_8$ orbifold models. We use a target-space duality anomaly cancellation and a unification of gauge couplings as constraints. It is shown that some models obtained through a systematical search realize the unification of SU(3) and SU(2) coupling constants.

Joseph D. Lykken, Scott Willenbrock

We explore the possibility of unification of gauge couplings near the Planck scale in models of extended technicolor. We observe that models of the form G X SU(3)_c X SU(2)_L X U(1)_Y cannot be realized, due to the presence of massless neutral Goldstone bosons (axions) and light charged pseudo-Goldstone bosons; thus, unification of the known forces near the

Martin Luescher, Rainer Sommer, Peter Weisz, Ulli Wolff

A non-perturbative finite-size scaling technique is used to study the evolution of the running coupling (in a certain adapted scheme) in the SU(3) Yang-Mills theory. At low energies contact is made with the fundamental dynamical scales, such as the string tension K, while at larger energies the coupling is shown to evolve according to perturbation theory. In

James B. Hartle

Spacetime must be foliable by spacelike surfaces for the quantum mechanics of matter fields to be formulated in terms of a unitarily evolving state vector defined on spacelike surfaces. When a spacetime cannot be foliated by spacelike surfaces, as in the case of spacetimes with closed timelike curves, a more general formulation of quantum mechanics is requir

J. Greensite

A transfer matrix formalism applicable to certain reparametrization invariant theories, including quantum gravity, is proposed. In this formulation it is found that every stationary state in quantum gravity satisfies a Wheeler-DeWitt equation, but each with a different value of the Planck mass; the value $m_{Planck}^4$ turns out to be proportional to the eig

P. F. González-Díaz

By assuming that only (i) bilocal vertex operators which are diagonal with respect to the basis for local field operators, and (ii) the convergent elements with nonzero positive energy of the density matrix representing the quantum state of multiply-connected wormholes, contribute the path integral that describes the effects of wormholes on ordinary matter f

Pedro F. Gonzalez-Diaz

A spontaneous symmetry breaking mechanism is used in quantum gravity to obtain a convergent positive definite density-matrix as the most general quantum state of Euclidean wormholes

A. V. Balatsky, Elihu Abrahams, D. J. Scalapino, J. R. Schrieffer

A new class of superconductors with the gap function {\it odd} under time reversal is considered. Some of the physical properties of these superconductors such as the Meissner effect, composite condensate, gapless spectrum and transition from the {\it odd} gap superconductor to the BCS state at lower temperatures are discussed.

M. Marsili

Pairs of particles of definite total and relative angular momentum provide a natural description for a two dimensional electron gas in a strong magnetic field. Two body operators take a simple form when expressed in terms of pair creation and destruction operators. The pair formalism is applied to the study of edge waves excitations. For $ν=1$ the operators

Satoshi Fujimoto, Norio Kawakami

The effect of spin-orbit interaction on persistent currents in mesoscopic Hubbard rings threaded by an Aharonov-Bohm flux is investigated putting stress on the orbital magnetism. The non-perturbative treatment of the spin-orbit interaction developed by Meir {\em et al.} is combined with the Bethe ansatz solution to deal with this problem exactly. We find tha

G. Fath, J. Solyom

We study low-lying excitations in the 1D $S=1$ antiferromagnetic valence-bond-solid (VBS) model. In a numerical calculation on finite systems the lowest excitations are found to form a discrete triplet branch, separated from the higher-lying continuum. The dispersion of these triplet excitations can be satisfactorily reproduced by assuming approximate wave f

Keith A. Olive, Nikos Prantzos, Sean Scully, Elisabeth Vangioni-Flam

We consider the evolution of the light elements ($Li, Be$ and $B$) incorporating the effects of their production by both neutrino process and cosmic-ray nucleosynthesis. We test the viability of the neutrino process to resolve the long standing problem of the $^{11}$B/$^{10}$B isotopic ratio which amounts to 4 at the time of the formation of the solar system

Hannu Kurki-Suonio, Grant Mathews

We explore constraints on various forms for the effective potential during inflation based upon a statistical comparison between inflation-generated fluctuations in the cosmic microwave background temperature and the COBE DMR results. Fits to the COBE 53A+B x 90A+B angular correlation function are obtained using simple analytic forms for the effective potent

Albert A. Zijlstra, Ralf Siebenmorgen

We present a radiative-transfer calculation which reproduces the infrared spectrum of the planetary nebula BD+30$^{\circ}$3639, fitting both the spectral energy distribution and the spatial extent at infrared wavelengths. We obtain an acceptable fit to most of the spectrum, including the infrared bands. The fit requires a distance of $\ge 2 \kpc$, which impl

S. Dalley

The problem of a periodic scalar field on a two-dimensional dynamical random lattice is studied with the inclusion of vortices in the action. Using a random matrix formulation, in the continuum limit for genus zero surfaces the partition function is found exactly, as a function of the chemical potential for vortices of unit winding number, at a specific radi

H. C. Eggers, P. Lipa

We review in brief the development and implementation of the Star integral, a tool yielding measurements of correlations much superior to conventional methods. A version for use in pion interferometry is explained. We also show how effects of non-poissonian overall multiplicity distributions may be eliminated if desired and quote results eliminating statisti

L. Durand, K. Honjo, R. Gandhi, H. Pi

We show that photoproduction cross sections recently measured by ZEUS and H-1 at HERA energies$^1$ are in agreement with our earlier prediction based on high-energy hadronic structure of the photon in the QCD minijet-type model$^2$. We present results of an improved calculation of the photoproduction cross section, in which the soft part, motivated by the Re

L. Chandar, E. Ercolessi

Yang-Mills theories on a 1+1 dimensional cylinder are considered. It is shown that canonical quantization can proceed following different routes, leading to inequivalent quantizations. The problem of the non-free action of the gauge group on the configuration space is also discussed. In particular we re-examine the relationship between ``$θ$-states" and

S. N. Solodukhin

Abtract: The 2D model of gravity with zweibeins $e^{a}$ and the Lorentz connection one-form $ω^{a}_{\ b}$ as independent gravitational variables is considered. The solutions of classical equations of motion which can be interpreted as cosmological ones are studied.

Y. Chen, S. M. Manning

We determine the asymptotic level spacing distribution for the Laguerre Ensemble in a single scaled interval, $(0,s)$, containing no levels, $E_{\bt}(0,s)$, via Dyson's Coulomb Fluid approach. For the $α=0$ Unitary-Laguerre Ensemble, we recover the exact spacing distribution found by both Edelman and Forrester, while for $α\neq 0$, the leading terms of $

Sonia Stanciu

We investigate the additional symmetries of several supersymmetric KP hierarchies: the SKP hierarchy of Manin and Radul, the $\hbox{SKP}_2$ hierarchy, and the Jacobian SKP hierarchy. In all three cases we find that the algebra of symmetries is isomorphic to the algebra of superdifferential operators, or equivalently $\SW_{1+\infty}$. These results seem to su

Ezra Getzler

Kazama has described an extension of the N=2 superconformal algebra in which the operator product of G^- with itself is singular. In this paper, we relate actions of this chiral algebra to Drinfeld's theory of Manin pairs, or equivalently, quasi-Lie bialgebras. We also show how to couple topological conformal field theories with this symmetry to topologi

E. K. Warburton, I. S. Towner, B. A. Brown

Calculations are presented for four relatively strong first-forbidden $β$ decays in the region A=11-16 in order to study the very large mesonic-exchange-current enhancement of the rank-zero components. The $μ^-$ capture on $^{16}$O is considered on the same footing. The wave functions utilized include up to 4$\hbarω$ excitations. Two-body exchange-current ma

R. Peschanski

Phenomenological and theoretical aspects of fragmentation for elementary particles (resp. nuclei) are discussed. It is shown that some concepts of classical fragmentation remain relevant in a microscopic framework, exhibiting non-trivial properties of quantum relativistic field theory (resp. lattice percolation). Email contact: pesch@amoco.saclay.cea.fr

John C. Baez

The loop representation of quantum gravity has many formal resemblances to a background-free string theory. In fact, its origins lie in attempts to treat the string theory of hadrons as an approximation to QCD, in which the strings represent flux tubes of the gauge field. A heuristic path-integral approach indicates a duality between background-free string t

Sudhakar Panda, Shibaji Roy

An infinite number of topological conformal algebras with varying central charges are explicitly shown to be present in $2d$ gravity (treated both in the conformal gauge and in the light-cone gauge) coupled to minimal matter. The central charges of the underlying $N=2$ theory in two different gauge choices are generically found to be different. The physical

E. Kiritsis

Duality symmetries for strings moving in non-trivial spacetime backgrounds are analysed. It is shown that for backgrounds generated from WZW and coset CFT models such duality symmetries are exact to all orders in string perturbation theory. Their implications for string dynamics in non-trivial/singular spacetimes are discussed. (Talk given at the EPS 93 Conf

Louis Crane, Louis H. Kauffman, David N. Yetter

We provide an explicit formula for the invariant of 4-manifolds introduced by Crane and Yetter (in hep-th 9301062). A consequence of our result is the existence of a combinatorial formula for the signature of a 4-manifold in terms of local data from a triangulation. Potential physical applications of our result exist in light of the fact that the Crane-Yette

Ali Mostafazadeh

The quantization of the superclassical system used in the proof of the index theorem results in a factor of $\hbar^{2}R/8 $ in the Hamiltonian. The path integral expression of the kernel is analyzed up to and including 2-loop order. The existence of the scalar curvature term is confirmed by comparing the linear term in the heat kernel expansion with the 2-lo

Ali Mostafazadeh, Arno Bohm

The topology of the non-adiabatic parameter space bundle is discussed for evolution of exact cyclic state vectors in Berry's original example of split angular momentum eigenstates. It turns out that the change in topology occurs at a critical frequency. The first Chern number that classifies these bundles is proportional to angular momentum. The non-adia

Ali Mostafazadeh

The Peierls bracket quantization scheme is applied to the supersymmetric system corresponding to the twisted spin index theorem. A detailed study of the quantum system is presented, and the Feynman propagator is exactly computed. The Green's function methods provide a direct derivation of the index formula. Note: This is essentially a new SUSY proof of t

R. Loll

We review some attempts of reformulating both gauge theory and general relativity in terms of holonomy-dependent loop variables. The emphasis lies on exhibiting the underlying mathematical structures, which often are not given due attention in physical applications. An extensive list of references is included.

J. A. Dixon

A search for supersymmetry anomalies requires an examination of the BRS cohomology of supersymmetric Yang-Mills coupled to chiral matter, and the physically interesting (on-shell) anomalies are those which cannot be eliminated using the equations of motion. An analysis of this cohomology problem shows that the simplest situation where a physically interestin

Ngee-Pong Chang

The QCD effective action at high T shows a manifest global chiral symmetry. And calculations show that the order parameter \psibarpsi vanishes above T_c. It has been popular to refer to this T_c as chiral symmetry restoration temperature because it fits into our prejudice that chiral symmetry is like an `ordered' state, and at high T it must become disor

R. Arnowitt, Pran Nath

The full parameter space of supergravity grand unified theory with $SU(5)$ type $p \rightarrow \barν K$ proton decay is analysed using renormalization group induced electroweak symmetry breaking under the restrictions that the universal scalar mass $m_o$ and gluino mass are $\leq 1$ TeV (no extreme fine tuning) and the Higgs triplet mass obeys $M_{H_3}/M_G <

Xiao-he Zhang, Peter Sutherland

A new, fully dynamic and self-consistent radiation hydrodynamics code, suitable for the calculation of supernovae light curves and continuum spectra, is described. It is a multigroup (frequency-dependent) code and includes all important $O(v/c)$ effects. It is applied to the model W7 of Nomoto, Thielemann, \& Yokoi (1984) for supernovae of type Ia. Radioacti

M. Haft, G. Raffelt, A. Weiss

On the basis of Braaten and Segel&#39;s representation of the electromagnetic dispersion relations in a QED plasma we check the numerical accuracy of several published analytic approximations to the plasma neutrino emission rates. As we find none of them satisfactory we derive a new analytic approximation which is accurate to within 4\%\ where the plasma pro

N. Caon, M. Capaccioli, M. D&#39;Onofrio

We have obtained the best fit to the light profiles of a luminosity limited sample of elliptical and S0 galaxies with a power law \rn, letting the exponent remain free rather than keeping it fixed at $1/n=1/4$ as in the well known \GV formula. The introduction of a free parameter in the fitting formula (ranging from $n=0.5$ for $<\re>=0.3$ kpc to $n=16$ for

J. J. Rodriguez-Nunez, Hans Beck

Starting from the Emery model, which is assumed to describe the copper oxygen planes, and including direct oxygen hopping matrix elements, we have been able to derive the effective t-J Hamiltonian for the copper orbitals using the Linked Cluster Expansion Method up to fourth order in the hybridization matrix element.

J. Gomis, J. Herrero, K. Kamimura, J. Roca

We introduce a particle mechanics model with Sp($2M$) gauge invariance. Different partial gauge-fixings by means of sl(2) embeddings on the gauge algebra lead to reduced models which are invariant under diffeomorphisms and classical non-linear \W-transformations as the residual gauge symmetries thus providing a set of models of gauge and matter fields couple

N. W. Schellingerhout, L. P. Kok, S. A. Coon, R. M. Adam

Just as $^3\roarrow{\rm He}$ can be approximately characterized as a polarized neutron target, polarized \Li6D has been advocated as a good {\em isoscalar} nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ``alpha + deuteron&#39;&#39; picture of \Li6, with the polarization of the nucl

Jörg Brendle

We show that several sigma-ideals related to porous sets have additivity omega_1 and cofinality 2^omega. This answers a question addressed by Miroslav Repick&#39;y.

Jörg Brendle

We discuss the effect of adding a single real (for various forcing notions adding reals) on cardinal invariants associated with the continuum (like the unbounding or the dominating number or the cardinals related to measure and category on the real line). For random and Cohen forcing, this question was investigated by Cicho&#39;n and Pawlikowski; for Hechler

Jörg Brendle

We study the set--theoretic combinatorics underlying the following two algebraic phenomena. (1) A subgroup G leq Z^omega exhibits the Specker phenomenon iff every homomorphism G to Z maps almost all unit vectors to 0. Let se be the size of the smallest G leq Z^omega exhibiting the Specker phenomenon. (2) Given an uncountably dimensional vector space E equipp

M. G. Schmidt, C. Schubert

Strassler&#39;s formulation of the string-derived Bern-Kosower formalism is reconsidered with particular emphasis on effective actions and form factors. Two- and three point form factors in the nonabelian effective action are calculated and compared with those obtained in the heat kernel approach of Barvinsky, Vilkovisky et al. We discuss the Fock-Schwinger

J. M. Prats

An alternative perturbative expansion in quantum mechanics which allows a full expression of the scaling arbitrariness is introduced. This expansion is examined in the case of the anharmonic oscillator and is conveniently resummed using a method which consists in introducing an energy cut-off that is carefully removed as the order of the expansion is increas

Bernhard Drabant, Wolfgang Weich

Generalizing the notion of continuous Hilbert space representations of compact topological groups we define unitary continuous correpresentations of $C^*$-completions of compact quantum group Hopf algebras on arbitrary Hilbert spaces. It is proved that the unitary continuous correpresentations decompose in finite dimensional irreducible correpresentations.

H. Nicolai

A new linear system is constructed for Poincaré supergravities in two dimensions. In contrast to previous results, which were based on the conformal gauge, this linear system involves the topological world sheet degrees of freedom (the Beltrami and super-Beltrami differentials). The associated spectral parameter likewise depends on these and is itself subjec

Andreas Albrecht

I study the quantum mechanics of a spin interacting with an ``apparatus&#39;&#39;. Although the evolution of the whole system is unitary, the spin evolution is not. The system is chosen so that the spin exhibits loss of quantum coherence, or ``wavefunction collapse&#39;&#39;, of the sort usually associated with a quantum measurement. The system is analyzed f

D. V. Fursaev

An asymptotic expansion of the trace of the heat kernel on a cone where the heat coefficients have a delta function behavior at the apex is obtained. It is used to derive the renormalized effective action and total energy of a self-interacting quantum scalar field on the cosmic string space-time. Analogy is pointed out with quantum theory with boundaries. Th

G. Giavarini, C. P. Martin, F. Ruiz Ruiz

We show that the renormalized vacuum expectation value of the Wilson loop for topologically massive abelian gauge theory in $\RR^3$ can be defined so that its large-mass limit be the renormalized vacuum expectation value of the Wilson loop for abelian Chern-Simons theory also in $\RR^3$.

R. W. Brown, M. E. Convery, M. A. Samuel

We discuss radiation zeros that are found in gauge tree amplitudes for processes involving multi-photon emission. Previous results are clarified by examples and by further elaboration. The conditions under which such amplitude zeros occur are identical in form to those for the single-photon zeros, and all radiated photons must travel parallel to each other.

V. Barger, R. J. N. Phillips

These lectures survey the present situation and future prospects in selected areas of particle physics phenomenology: (1) the top quark, (2) the Higgs boson in the Standard Model, (3) strong $WW$ scattering, (4) supersymmetry, (5) the Higgs sector in minimal supersymmetry, and (6) low-energy constraints on supersymmetry.

K. S. Babu, S. M. Barr

It is a well--known problem that in supersymmetric models there are new CP--violating phases which, if unsuppressed, would give a neutron electric dipole moment $10^2$ to $10^3$ times the present experimental limit. Here we propose that these new phases are suppressed by CP invariance, which is broken spontaneously at a high scale and that this breaking show

K. Hagiawara, M. L. Stong

We study possible deviations from the Standard Model in the reaction $e^+e^- \to Zϕ$, where $ϕ$ denotes a spinless neutral boson. We show how the $Z$ decay angular correlation can be used to extract detailed information on the $ϕ$ couplings, such as the parity of $ϕ$, radiatively induced form factor effects and possible CP violation in the scalar sector. Con

P. Bedaque, A. Das, V. S. Mathur

In the pole-dominance model for the two-body nonleptonic decays of charmed mesons $D \rightarrow PV$ and $D \rightarrow VV$, it is shown that the contributions of the intermediate pseudoscalar and the axial-vector meson poles cancel each other in the annihilation diagrams in the chiral limit. In the same limit, the annihilation diagrams for the $D \rightarro

R. Muñoz-Tapia, W. J. Stirling

The light gluino hypothesis can explain the apparent incompatibility between the measurements of $\as$ at low- and high-energy. Such gluinos are produced directlyin four-jet events, for which we perform a detailed analysis. Because the jet energies are not large, the effect of the non-zero gluino mass is important. We take the gluino mass into account in the

Boro Grubisic, Vincent Moncrief

We show that for $U(1)$-symmetric spacetimes on $S^3 \times R$ a constant of motion associated with the well known Geroch transformation, a functional $K[h_{ij},π^{ij}]$, quadratic in gravitational momenta, is strictly positive in an open subset of the set of all $U(1)$-symmetric initial data, and therefore not weakly zero. The Mixmaster initial data appear

B. de Wit, H. J. Matschull, H. Nicolai

To clarify some issues raised by D&#39;Eath&#39;s recent proposal for the physical states of $N=1$ supergravity in four dimensions, we study pure (topological) $N=2$ supergravity in three dimensions, which is formally very similar, but much easier to solve. The wave functionals solving the quantum constraints can be understood in terms of arbitrary functions

Liang Chen, A. -M. S. Tremblay

The observed magnetic spin susceptibility of high-temperature superconductors such as La$_{2- x}$Sr$_x$CuO$_4$ increases when $x$ increases from zero, i.e. as one dopes away from half-filling. Recent Monte Carlo simulations of A. Moreo (Phys. Rev. B {\bf 48}, 3380 (1993)) suggest that this behavior can be reproduced by the two-dimensional Hubbard model only

Mitchell C. Begelman, P. Meszaros, Martin J. Rees

If gamma-ray bursts originate in our Galaxy, they probably involve violent disturbances in the magnetospheres of neutron stars. Any event of this kind is likely to trigger the sudden expulsion of magnetic flux and plasma at relativistic speed. We show that such ejecta would be braked by the interstellar medium (ISM), and that a gamma-ray flash with duration

P. Meszaros, M. J. Rees

In almost any scenario for &#39;cosmological&#39; gamma-ray bursts (and in many models where they originate in our own Galaxy), the initial energy density is so large that the resulting relativistic plasma expands with $v\sim c$ producing a blast wave ahead of it and a reverse shock moving into the ejecta, as it ploughs into the external medium. We evaluate

T. Norretranders, J. Bohr, S. Brunak

Fluids suspended in expanding laboratory systems cavitate into Voronoi foams that degenerate through secondary cavitation of the foam walls. This robust morphological mechanism results from a virtual competition for space between the cavities. In cosmology, Voronoi foams are known to explain important features of the large scale structure, but the physical m

S. Kalyana Rama

We present the static, spherically symmetric solutions of the low energy $d = 4$ string. They form a simple generalisation of the Schwarzschild solution and describe the gravitational field of a spherical star in perturbative string theory. If the Robertson parameter $γ$ is different from one, these solutions describe singular objects with naked singularitie

J. S. Dowker

A derivation of the Cesàro-Fedorov relation from the Selberg trace formula on an orbifolded 2-sphere is elaborated and extended to higher dimensions using the known heat-kernel coefficients for manifolds with piecewise-linear boundaries. Several results are obtained that relate the coefficients, $b_i$, in the Shephard-Todd polynomial to the geometry of the f

R. Okamoto, K. Suzuki, P. J. Ellis, Jifa Hao

The Hermitian effective interaction can be well-approximated by (R+R^dagger)/2 if the eigenvalues of omega^dagger omega are small or state-independent(degenerate), where R is the standard non-Hermitian effective interaction and omega maps the model-space states onto the excluded space. An error bound on this approximation is given.

K. Varga

We present a computer code that analytically evaluates the matrix elements of the microscopic nuclear Hamiltonian and unity operator between Slater determinants of displaced gaussian single particle orbits. Such matrix elements appear in the generator coordinate model and the resonating group model versions of the microscopic multicluster calculations.

K. Varga

We present explicit analytical formulae for two-body matrix elements between Pauli-projected single-particle orbits generated by gaussians shifted from the centre of a nuclear core, which is populated by nucleons occupying harmonic-oscillator orbits. Such shifted gaussian orbits appear in the generator-coordinate model of two-cluster systems and, as ingredie

M. J. Musolf, T. W. Donnelly

Meson-exchange current contributions to the strangeness radius of $^4$He are computed in the one-boson exchange approximation. It is found that these contributions introduce a $\lapp$10\% correction to the one-body contribution. They should not, therefore, hamper the extraction of the nucleon strangeness radius from the parity-violating electron-$^4$He asymm

S. Loh T. S. Biro U. Mosel

In high-energy nucleon-nucleon-collisions large meson production rates are observed. As an alternative to meson exchange models here we propose a nonperturbative treatment of the quark-antiquark production from the mean field of colliding nucleon bags. Source terms for particles and antiparticles are developed in a semiclassical quark transport description a

N. Tajima

Rotational bands with (neutron h_11/2)^1 (proton h_11/2)^1 configurations are studied using a particle-rotor model in which a proton and a neutron quasiparticles interacting through a zero-range force are coupled with a triaxial rotor. It is shown for 124Cs that one can reproduce the signature dependence of energy and B(M1)/B(E2) ratio best when one takes in

Andreas Blass

We survey some connections between topological dynamics, semigroups of ultrafilters, and combinatorics. As an application, we give a proof, based on ideas of Bergelson and Hindman, of the Hales-Jewett partition theorem.

R. MacKenzie, P. K. Panigrahi, S. Sakhi

We analyse a $2+1$ dimensional model with charged, relativistic fermions interacting through a four-Fermi term. Taking advantage of its large-$N$ renormalizability, the various phases of this model are studied at finite temperature and beyond the leading order in $1/N$. Although the vacuum expectation value (VEV) of a charged order parameter is zero at any n

D. Z. Freedman, P. E. Haagensen, K. Johnson, J. I. Latorre

The Gauss law constraint in the Hamiltonian form of the $SU(2)$ gauge theory of gluons is satisfied by any functional of the gauge invariant tensor variable $ϕ^{ij} = B^{ia} B^{ja}$. Arguments are given that the tensor $G_{ij} = (ϕ^{-1})_{ij}\,\det B$ is a more appropriate variable. When the Hamiltonian is expressed in terms of $ϕ$ or $G$, the quantity $Γ^i_

Joseph A. Minahan, Alexios P. Polychronakos

We consider two dimensional U(N) QCD on the cylinder with a timelike Wilson line in an arbitrary representation. We show that the theory is equivalent to N fermions with internal degrees of freedom which interact among themselves with a generalized Sutherland-type interaction. By evaluating the expectation value of the Wilson line in the original theory we e

Itzhak Bars

Based on lectures delivered at (1) the AMS meeting at USC, Nov. 1992 (2) Conference on Quantum Aspects of Black Holes, ITP, UC- Santa %Barbara, %%June 1993. (3) 25th Summer Institute, Ecole Normale Superieure, % Paris, Aug. 1992. To appear in &#34;Interface Between Mathematics and Physics&#34;, Ed. S.-T. Yau. 1--Itroduction to String Theory in Curved Spaceti

Suresh Govindarajan, T. Jayaraman, Varghese John

We compute all string tree level correlation functions of vertex operators in $c<1$ string theory. This is done by using the ring structure of the theory. In order to study the multicritical behaviour, we calculate the correlation functions after perturbation by physical vertex operators. We show that the $(2k-1,2)$ models can be obtained from the $(1,2)$ mo

Andrzej Czarnecki, Andrei I. Davydychev

We calculate next-to-leading QCD corrections to the decay $H^+ \to u\bar d$ for generic up and down quarks in the final state. A recently developed algorithm for evaluation of massive two-loop Feynman diagrams is employed to calculate renormalization constants of the charged Higgs boson. The origin and summation of large logarithmic corrections to the decay

U. Baur, A. Stange

We calculate the $pp\rightarrow t\bar tγ+X\rightarrow Wγ+ X$ cross section at SSC energies. Approximately 40\% of the total cross section originates from photon bremsstrahlung off the final state jet in $t\bar tj$ production. Without cuts restricting the hadronic activity, the $t\bar tγ$ rate is a factor 10 (2) larger than the tree level $Wγ$ cross section f

G. Belanger, D. London, H. Nadeau

The single production of leptoquarks in $e^+e^-$, $eγ$ and $γγ$ linear colliders is discussed. We show that these new particles could be seen in such machines even if their mass is close to the kinematic limit. (Invited talk given by G.B. at the ``Workshop on Physics and Experiments at Linear $e^+e^-$ Colliders&#39;&#39;, Waikoloa, Hawaii, April 26-30, 1993.

M. Laine

Bubble growth as a detonation is studied in the context of cosmological phase transitions. It is proved that the so called Chapman-Jouguet hypothesis, which restricts the types of detonations that can occur in spherically symmetric chemical burning, does not hold in the case of phase transitions. Therefore a much larger class of detonation solutions exists i

Gye T. Park

We perform a combined analysis of two stringent constraints on two Higgs doublet model, coming from the recently announced CLEO II bound on $B(b \rightarrow s γ)$ and $Z \rightarrow b \overline b$ and from the recent LEP data on the ratio $Γ(Z\rightarrow b\overline b)\over{Γ(Z\rightarrow hadrons)}$. We include one-loop vertex corrections to $Z \rightarrow b

J. Kiskis

This paper is a study of some of the critical properties of a simple model for flux. The model is motivated by gauge theory and is equivalent to the Ising model in three dimensions. The phase with condensed flux is studied. This is the ordered phase of the Ising model and the high temperature, deconfined phase of the gauge theory. The flux picture will be us