September 1993 arXiv papers — page 5

Bertrand Duplantier

It has been recently argued that interacting self-avoiding walks (ISAW) of length $ \ell , $ in their low temperature phase (i.e. below the $ Θ$-point) should have a partition function of the form: $$ Q_{\ell} \sim μ^{ \ell}_ 0μ^{ \ell^ σ}_ 1\ell^{ γ-1}\ , \eqno $$ where $ μ_ 0(T) $ and $ μ_ 1(T) $ are respectively bulk and perimeter monomer fugacities, both

F. Gebhard, A. Girndt, A. E. Ruckenstein

We discuss the transition from a metal to charge or spin insulating phases characterized by the opening of a gap in the charge or spin excitation spectra, respectively. These transitions are addressed within the context of two exactly solvable Hubbard and tJ chains with long range, $1/r$ hopping. We discuss the specific heat, compressibility, and magnetic su

N. J. Balmforth, E. A. Spiegel, C. Tresser

We present a method for computing the topological entropy of one-dimensional maps. As an approximation scheme, the algorithm converges rapidly and provides both upper and lower bounds.

N. J. Balmforth, G. R. Ierley, E. A. Spiegel

We study a third-order nonlinear ordinary differential equation whose solutions, under certain specific conditions, are individual pulses. These correspond to homoclinic orbits in the phase space of the equation and we study the possible pulse types in some detail. Sufficiently close to the conditions under which a homoclinic orbit exists, the solutions take

Adi Nusser, Marc Davis

We present a new method for recovering the underlying velocity field from an observed distribution of galaxies in redshift space. The method is based on a kinematic Zel'dovich relation between the velocity and density fields in redshift space. This relation is expressed in a differential equation slightly modified from the usual Poisson equation, and whi

Enrico Nardi

Generation dependent discrete symmetries often appear in models derived from superstring theories. In particular, in the framework of E$_6$ models the presence of such symmetries is required in order to allow for the radiative generation of naturally small neutrino masses. Recently it was shown that by imposing suitable generation dependent discrete symmetri

E. Alvarez, L. Alvarez-Gaume, J. L. F. Barbon, Y. Lozano

We explore some of the global aspects of duality transformations in String Theory and Field Theory. We analyze in some detail the equivalence of dual models corresponding to different topologies at the level of the partition function and in terms of the operator correspondence for abelian duality. We analyze the behavior of the cosmological constant under th

M. Fabbrichesi, R. Pettorini, G. Veneziano, G. A. Vilkovisky

This is a revised version of our previous paper by the same name and preprint number. It contains various changes, two figures and new results in sect.5. We propose a new approach to four-dimensional Planckian-energy scattering in which the phase of the ${\cal S}$-matrix is written---to leading order in $\hbar$ and to all orders in $R/b =Gs/J$---in terms of

G. F. Bertsch, P. Danielewicz, M. Herrmann

The analysis of meson correlations by Hanbury-Brown--Twiss interferometry is tested with a simple model of meson production by resonance decay. We derive conditions which should be satisfied in order to relate the measured momentum correlation to the classical source size. The Bose correlation effects are apparent in both the ratio of meson pairs to singles

H. Lu, C. N. Pope, X. J. Wang, K. W. Xu

We present a simple procedure for constructing the complete cohomology of the BRST operator of the two-scalar and multi-scalar $W_3$ strings. The method consists of obtaining two level--15 physical operators in the two-scalar $W_3$ string that are invertible, and that can normal order with all other physical operators. They can be used to map all physical op

B. Enriquez, A. Orlov, V. Rubtsov

We apply the procedure of Magri and Weinstein to produce an infinity of compatible Poisson structures on a bihamiltonian manifold, to the case of the KdV phase space. The higher Gel'fand-Dikii structures thus obtained contain non local terms, which we express with the help of the r.h.s. of the KdV hierarchy. We also give a generating function for all the

J. A. de Azcárraga, P. P. Kulish, F. Ródenas

We express the defining relations of the $q$-deformed Minkowski space algebra as well as that of the corresponding derivatives and differentials in the form of reflection equations. This formulation encompasses the covariance properties with respect the quantum Lorentz group action in a straightforward way.

Shoichi Ichinose

We present a grapical way to describe invariants and covariants in the (4 dim) general relativity. This makes us free from the complexity of suffixes . Two new off-shell relations between (mass)$\ast\ast 6$\ invariants are obtained. These are important for 2-loop off-shell calculation in the perturbative quantum gravity. We list up all independent invarians

Andrija Rašin, João P. Silva

Approximate flavor symmetries in the quark sector have been used as a handle on physics beyond the Standard Model. Due to the great interest in neutrino masses and mixings and the wealth of existing and proposed neutrino experiments it is important to extend this analysis to the leptonic sector. We show that in the see-saw mechanism, the neutrino masses and

D. Boyanovsky, H. J. de Vega, R. Holman

The dynamics of typical phase transitions is studied out of equilibrium in weakly coupled inflaton-type scalar field theories in Minkowski space. The shortcomings of the effective potential and equilibrium descriptions are pointed out. A case of a rapid supercooling from $T_i>T_c$ to $T_f \ll T_c$ is considered. The equations of motion up to one-loop for the

M. B. Voloshin

The probability of destruction of a metastable vacuum state by the field of a highly virtual particle with energy $E$ is calculated for a (3+1) dimensional theory in the leading WKB approximation in the thin-wall limit. It is found that the induced nucleation rate of bubbles, capable of expansion, is exponentially small at any energy. The negative exponentia

Mikolaj Misiak

Since several years there exists a question whether the dimensional reduction and the usual dimensional regularization give different results for the QCD-improved $b \rightarrow s γ$ and $b \rightarrow s$ $gluon$ decay rates. Here it is demonstrated explicitly that this is not the case: As long as physically meaningful quantities are considered, the results

J. D. Bjorken, K. L. Kowalski, C. C. Taylor

We speculate that, in very high energy hadronic collisions, large fireballs may be produced with interiors which have anomalous chiral order parameters. Such a process would result in radiation of pions with distinctive momentum and isospin distributions, and may provide an explanation of Centauro and related phenomena in cosmic-ray events. The phenomenology

V. S. Fadin, V. A. Khoze, A. D. Martin

We present a \lq\lq theorem" which quantifies, for inclusive processes, the level of suppression of the radiative interference effects between the production and decay stages of heavy {\it unstable} particles. The theorem, which is based on very general physical arguments, is applicable to all orders in the coupling.

Kenichiro Aoki

The contribution to the $ρ$--parameter of the quark--Higgs sector of the supersymmetric standard model is computed non--perturbatively using the large--$\nf$ expansion for the case tan$β$=0. An explicit formula is found for the $ρ$--parameter which is ill-defined unless the triviality cutoff is taken into account. The cutoff dependence of the $ρ$--parameter

Hilmar Forkel, Manoj K. Banerjee

We study the role of direct (i.e. small-scale) instantons in QCD correlation functions for the nucleon. They generate sizeable, nonperturbative corrections to the conventional operator product expansion, which improve the quality of both QCD nucleon sum rules and cure the long-standing stability problem, in particular, of the chirally odd sum-rule.

Y. Iwasaki, K. Kanaya, Leo Kärkkäinen, K. Rummukainen

We calculate the tension $σ$ of the interface between the confined and deconfined phases by the histogram method in SU(3) lattice gauge theory for temporal extents of 4 and 6 using the recent high-statistics data by QCDPAX collaboration. The results are $σ/T_c^3 = 0.0292(22)$ and 0.0218(33) for $N_t=4$ and 6, respectively. The ratio $σ/T_c^3$ shows a scaling

H. W. Braden, Takashi Suzuki

The classical $R$-matrix structure for the $n$-particle Calogero-Moser models with (type IV) elliptic potentials is investigated. We show there is no momentum independent $R$-matrix (without spectral parameter) when $n\ge4$. The assumption of momentum independence is sufficient to reproduce the dynamical $R$-matrices of Avan and Talon for the type I,II,III d

E. Hummel, J. A. Tjon

Within a quasipotential framework a relativistic analysis is presented of the deuteron current. Assuming that the singularities from the nucleon propagators are important, a so-called equal time approximation of the current is constructed. This is applied to both elastic and inelastic electron scattering. As dynamical model the relativistic one boson exchang

S. G. Cooper, R. S. Mackintosh, A. Csoto, R. G. Lovas

Phase shifts for $α$ + nucleon scattering generated by a multichannel RGM model of the five-nucleon system are subjected to iterative-perturbative ``mixed-case" inversion for energies below the reaction threshold. The resulting phase-equivalent potentials are compared with local potentials calculated from the inversion of empirical phase shifts. A strong

Michele Maggiore

We show that a deformation of the Heisenberg algebra which depends on a dimensionful parameter $κ$ is the algebraic structure which underlies the generalized uncertainty principle in quantum gravity. The deformed algebra and therefore the form of the generalized uncertainty principle are fixed uniquely by rather simple assumptions. The string theory result i

Demosthenes Ellinas, Vassilios Kovanis

In the analytic-Bargmann representation associated with the harmonic oscillator and spin coherent states, the wavefunction as entire complex functions can be factorized in terms of their zeros in a unique way. The Schrödinger equation of motion for the wavefunction is turned to a system of equations for its zeros. The motion of these zeros as a non-linear fl

Demosthenes Ellinas

A star-product formalism describing deformations of the standard quantum mechanical harmonic oscillator is introduced. A number of existing generalized oscillators occur as particular choises of star-products between the elements of the ordinary oscillator algebra. Star dynamics and coherent states are introduced and studied.

Martin Cederwall, Christian R. Preitschopf

We investigate the seven-sphere as a group-like manifold and its extension to a Kac-Moody-like algebra. Covariance properties and tensorial composition of spinors under $S^7$ are defined. The relation to Malcev algebras is established. The consequences for octonionic projective spaces are examined. Current algebras are formulated and their anomalies are deri

Tetsuo Deguchi

We discuss multivariable invariants of colored links associated with the $N$-dimensional root of unity representation of the quantum group. The invariants for $N>2$ are generalizations of the multi-variable Alexander polynomial. The invariants vanish for disconnected links. We review the definition of the invariants through (1,1)-tangles. When $(N,3)=1$ and

Brian Hendee Smith

Delicate cancellations among diagrams can result in the vanishing of threshold amplitudes in the standard model. This phenomenon is investigated for multi-Higgs production by scalar, vector, and fermionic fields. A surprising gap is found where although the tree-level amplitude for $2$ incoming gauge bosons to produce $N_v$ particle may vanish, the amplitude

A. Le Yaouanc, O. Pène

We argue that a Tau-Charm factory (TCF) could improve our knowledge of CKM matrix elements since it is an incomparable tool to check the models and methods applied to extract $V_{bu}$ from $B$ decay partial widths. We report on some recent proposals to improve on parton model. Turning to exclusive decays, we compare the predictions from quark models, QCD sum

B. Schwesinger, H. Walliser

We derive an analytic expression for the Kroll-Ruderman amplitude up to the order 1/N_C for general Skyrme-type models of the nucleon. Due to the degeneracy of intermediate N- and Delta-states we find deviations from the standard low-energy theorem for the photoproduction of neutral pions.

Xiao-Gang He, B. McKellar

We study contributions to $b \rightarrow s γ$ from anomalous $WWγ$ interactions. Although these anomalous interactions are not renormalizable, the contributions are cut-off independent. Using recent results from the CLEO collaboration on inclusive radiative B decays, we obtain bounds for the anomalous CP conserving and CP violating couplings. The constraints

Avinash Dhar, Gautam Mandal, Spenta R. Wadia

We complete the proof of bosonization of noninteracting nonrelativistic fermions in one space dimension by deriving the bosonized action using $W_\infty$ coherent states in the fermion path-integral. This action was earlier derived by us using the method of coadjoint orbits. We also discuss the classical limit of the bosonized theory and indicate the precise

Taehoon Ahn, Seunghwan Kim

We have studied a chaotic transport in a two-dimensional periodic vortical flow under a time-dependent perturbation with period T where the global diffusion occurs along the stochastic web. By using the Melnikov method we construct the separatrix map describing the approximate dynamics near the saddle separatrices. Focusing on the small T, the width of the s

Mikhail Lyubich

A while ago MLC (the conjecture that the Mandelbrot set is locally connected) was proven for quasi-hyperbolic points by Douady and Hubbard, and for boundaries of hyperbolic components by Yoccoz. More recently Yoccoz proved MLC for all at most finitely renormalizable parameter values. One of our goals is to prove MLC for some infinitely renormalizable paramet

U. Baur, D. Zeppenfeld

We investigate the electroweak process $qq\to qqW$, {\it i.e.} $W$ production via $Wγ$ and $WZ$ fusion, as a probe for nonstandard $WWγ$ and $WWZ$ vertices at hadron supercolliders. Triggering on events with one very forward and one very backward jet while requiring the $W$ decay lepton to be central, strongly enhances the triple gauge boson vertex contribut

J. F. Gunion

I briefly review the crucial role an $\emem$ linear collider could play in unravelling the nature of a non-minimal Higgs sector and/or strongly-interacting $WW$ sector.

J. C. D'Olivo, Jose F. Nieves

We examine the relation between the damping rate of a massless, chiral fermion that propagates in a medium, and the rate $Γ$ of approach to equilibrium. It is proven that these quantities are equal, by showing that they are given by the same formula in terms of the imaginary part of the self-energy evaluated at the energy of the propagating fermion mode. Thi

Bijan Haeri

The Cornwall-Jackiw-Tomboulis effective potential is modified to include a functional dependence on the fermion-gauge particle vertex, and applied to a quark confining model of chiral symmetry breaking.

Anna Beliakova, Bergfinnur Durhuus

On basis of generalized 6j-symbols we give a formulation of topological quantum field theories for 3-manifolds including observables in the form of coloured graphs. It is shown that the 6j-symbols associated with deformations of the classical groups at simple even roots of unity provide examples of this construction. Calculational methods are developed which

M. Baldo, E. G. Lanza, A. Rapisarda

We discuss the relevance of chaotic scattering in heavy--ion reactions at energies around the Coulomb barrier. A model in two and three dimensions which takes into account rotational degrees of freedom is discussed both classically and quantum-mechanically. The typical chaotic features found in this description of heavy-ion collisions are connected with the

C. Ciofi degli Atti, E. Pace, G. Salmé

The theory of inclusive lepton scattering of polarized leptons by polarized J = 1/2 hadrons is presented and the origin of different expressions for the polarized nuclear response function appearing in the literature is explained. The sensitivity of the longitudinal asymmetry upon the neutron form factors is investigated.

Ashoke Sen, Barton Zwiebach

We give a generally covariant description, in the sense of symplectic geometry, of gauge transformations in Batalin-Vilkovisky quantization. Gauge transformations exist not only at the classical level, but also at the quantum level, where they leave the action-weighted measure $dμ_S = dμe^{2S/\hbar}$ invariant. The quantum gauge transformations and their Lie

Alexei Morozov, Luc Vinet

We describe a representation of the $q$--hypergeometric functions of one variable in terms of correlators of vertex operators made out of free scalar fields on the Riemann sphere.

Martin Bordemann, Jens Hoppe

By explicitly eliminating all gauge degrees of freedom in the $3+1$-gauge description of a classical relativistic (open) membrane moving in $\Real^3$ we derive a $2+1$-dimensional nonlinear wave equation of Born-Infeld type for the graph $z(t,x,y)$ which is invariant under the Poincaré group in four dimensions. Alternatively, we determine the world-volume of

M Gasperini, G Veneziano

The inflationary scenarios suggested by the duality properties of string cosmology in the Brans-Dicke (or String) frame are shown to correspond to accelerated contraction (deflation) when Weyl-transformed to the Einstein frame. We point out that the basic virtues of inflation (solving the flatness and horizon problems, amplifying vacuum fluctuations, etc.) h

H. J. de Vega, A. González--Ruiz

The Nested Bethe Ansatz is generalized to open boundary conditions. This is used to find the exact eigenvectors and eigenvalues of the $A_{n-1}$ vertex model with fixed open boundary conditions and the corresponding $SU_{q}(n)$ invariant hamiltonian. The Bethe Ansatz equations obtained are solved in the thermodynamic limit giving the vertex model free energy

Gerald Kelnhofer

Consistent and covariant Lorentz and diffeomorphism anomalies are investigated in terms of the geometry of the universal bundle for gravity. This bundle is explicitly constructed and its geometrical structure will be studied. By means of the local index theorem for families of Bismut and Freed the consistent gravitational anomalies are calculated. Covariant

K. S. Babu, C. N. Leung, J. Pantaleone

A small neutrino Majorana mass can arise in the Standard Model as an effective dimension 5 operator. We calculate the renormalization of this operator in the minimal Standard Model and in its two-Higgs-doublet and supersymmetric extensions. Renormalization from the scale of lepton number violation (e.g., the Planck scale or a GUT scale) to the weak scale dec

F. del Aguila, M. Cvetic, P. Langacker

We review present Z' bounds, discuss future Z' constraints from TEVATRON, HERA and LEP, and give a brief review of the Z' diagnostics at future colliders.

A. Dobado, A. Lopez

We consider the minimal low-energy action for gravity up to six derivatives which is renormalizable at the two-loop level modulo higher derivative corrections. Then we study the classical solutions corresponding to the Schwarzschild and the Robertson-Walker metrics. In the first case we find a singularity close to the gravitational radius and in the second c

S. Fajfer

Corrections to $K\rightarrowπππ$ induced by vector and scalar meson exchange are investigated within chiral perturbation theory.

A. Bottino, V. de Alfaro, N. Fornengo, G. Mignola

Evaluations of the event rates relevant to direct search for dark matter neutralino are presented for a wide range of neutralino masses and for various detector materials of preeminent interest. Differential and total rates are appropriately weighted over the local neutralino density expected on theoretical grounds.

A. Bottino, V. de Alfaro, N. Fornengo, G. Mignola

The neutralino relic abundance is evaluated for a wide range of the neutralino mass, ${\rm 20\ GeV} \leq m_χ\leq {\rm 1\ TeV}$, by taking into account the full set of final states in the neutralino-neutralino annihilation. The analysis is performed in the Minimal SuSy Standard Model; it is not restricted by stringent GUT assumptions but only constrained by p

I. I. Balitsky, M. Beneke, V. M. Braun

Contrary to some previous claims, we find a sizable instanton contribution to the finite energy sum rule used to extract the value of the strong coupling from the measured $τ$ decay widths. It is of the same order of magnitude as standard nonperturbative corrections induced by vacuum quark and gluon condensates. Our result indicates that there might be no hi

UKQCD Collaboration

We present results for light hadrons composed of both degenerate and non-degenerate quarks in quenched lattice QCD. We calculate masses and decay constants using 60 gauge configurations with an $O(a)$--improved fermion action at $β= 6.2$. Using the $ρ$ mass to set the scale, we find hadron masses within two to three standard deviations of the experimental va

R. Bacon, E. Emsellem, G. Monnet, J. L. Nieto

Sub-arcsecond imagery (HRCAM, 0".35 - 0".57 FWHM) and two-dimensional spectrography (TIGER, 0".9 FWHM) of the central nucleus of M31 have been obtained at CFHT. The photometric data clearly show the double-peaked nucleus, in excellent agreement with a recent HST image by Lauer et al. 1993. We built deconvolved surface brightness models, using the

P. Coleman, E. Miranda, A. Tsvelik

We consider the possibility that instabilities of the Abrikosov-Suhl resonance lead to new fixed point behavior of the Kondo effect in a lattice environment. In one scenario, a pairing component to the resonant scattering develops in the Kondo lattice, leading to an odd frequency superconductor. We discuss experiments that can discriminate between this pictu

J. F. Gunion

We demonstrate that an invisibly decaying Higgs boson with Standard Model coupling strength to top--anti-top can be detected at the LHC for masses up to about 250 GeV.

D. van der Marel

The phase diagram of the unconstrained $t-J$ model is calculated using the random phase approximation. It is found that the extended $s$ and the $d_{x^2-y^2}$-channels are {\em not} degenerate near half filling. Extended $s$-pairing with a low $T_c$ occurs only for a band containing less then 0.4 electrons or holes per unit cell, whereas in a large region ar

Sean A. Hayward, Tetsuya Shiromizu, Ken-ichi Nakao

In a space-time with cosmological constant $Λ>0$ and matter satisfying the dominant energy condition, the area of a black or white hole cannot exceed $4π/Λ$. This applies to event horizons where defined, i.e. in an asymptotically deSitter space-time, and to outer trapping horizons (cf. apparent horizons) in any space-time. The bound is attained if and only i

Sergei V. Zenkin

We discuss the phase structure of a lattice Higgs-Yukawa system in the variational mean field approximation with contributions of fermionic determinant being calculated in a ladder approximation. In particular, we demonstrate that in this approximation the ferrimagnetic phase in the $Z_2$ model with naive fermions can appear as an artifact of a finite lattic

Hiroaki Nakano, Yusuke Yoshida

We present a new procedure for improving the effective potential by using renormalization group equation (RGE) in the presence of several mass scales. We propose a modification of the mass-dependent (MD) renormalization scheme, MDbar scheme, so that the scalar mass parameter runs at most logarithmically on the one hand and the decoupling of heavy particles i

Valery Frolov, Igor Novikov

Modes of physical fields which are located inside a horizon and which cannot be observed by a distant observer are identified with dynamical degrees of freedom of a black hole. A new invariant statistical mechanical definition of a black-hole's entropy is proposed. It is shown that the main contribution to the entropy is given by thermally excited `invisible

V. V. Nesterenko

Consideration of the model of the relativistic particle with curvature and torsion in the three-dimensional space-time shows that the squaring of the primary constraints entails a wrong result. The complete set of the Hamiltonian constraints arising here correspond to another model with an action similar but not identical with the initial action.

Nemanja Kaloper

Two solutions of stringy gravity in three and four dimensions which admit interpretation as a black hole and a black string, respectively, are discussed. It is demonstrated that they are exact WZWN nonlinear sigma models to all orders in the inverse string tension, and hence represent exact conformal field theories on the world-sheet. Furthermore, since the

Nicholas Dorey, James Hughes, Michael P. Mattis

We apply the method of collective coordinate quantization to a model of solitons in two spacetime dimensions with a global $U(1)$ symmetry. In particular we consider the dynamics of the charged states associated with rotational excitations of the soliton in the internal space and their interactions with the quanta of the background field (mesons). By solving

John Palmer, Morris Beatty, Craig A. Tracy

Correlation functions for holonomic fields on the Poincare' disk are analyzed. The two point functions are shown to be expressible in terms of Painleve' functions of type VI.

H. J. de Vega, I. L. Egusquiza

The string equations of motion and constraints are solved for a ring shaped Ansatz in cosmological and black hole spacetimes. In FRW universes with arbitrary power behavior [$R(X^0) = a\;|X^0|^{\a}\, $], the asymptotic form of the solution is found for both $X^0 \to 0$ and $X^0 \to \infty$ and we plot the numerical solution for all times. Right after the big

B. Sathiapalan

The issue of gauge invariances in the sigma model formalism is discussed at the free and interacting level. The problem of deriving gauge invariant interacting equations can be addressed using the proper time formalism. This formalism is discussed, both for point particles and strings. The covariant Klein Gordon equation arises in a geometric way from the bo

Z. Bajnok

Using the fusion principle of Bauer et al. we give explicit expressions for some null vectors in the highest weight representations of the \bc algebra in two different forms. These null vectors are the generalization of the Virasoro ones described by Benoit and Saint-Aubin and analogues of the $W_3$ ones constructed by Bowcock and Watts. We find connection b

Cristina Manuel, Rolf Tarrach

Some quantum mechanical potentials, singular at short distances, lead to ultraviolet divergences when used in perturbation theory. Exactly as in quantum field theories, but much simpler, regularization and renormalization lead to finite physical results, which compare correctly to the exact ones. The Dirac delta potential, because of its relevance to trivial

Yu. Makeenko, K. Zarembo

We study fermionic one-matrix, two-matrix and $D$-dimensional gauge invariant matrix models. In all cases we derive loop equations which unambiguously determine the large-$N$ solution. For the one-matrix case the solution is obtained for an arbitrary interaction potential and turns out to be equivalent to the one for the Hermitean one-matrix model with a log

Alan Weinstein

The Schwartz kernel of the multiplication operation on a quantum torus is shown to be the distributional boundary value of a classical multivariate theta function. The kernel satisfies a Schrödinger equation in which the role of time is played by the deformation parameter $\hbar$ and the role of the hamiltonian by a Poisson structure. At least in some specia

Ivan K. Kostov

We explain, in a slightly modified form, an old construction allowing to reformulate the U(N) gauge theory defined on a D-dimensional lattice as a theory of lattice strings (a statistical model of random surfaces). The world surface of the lattice string is allowed to have pointlike singularities (branch points) located not only at the sites of the lattice,

V. Berezinsky, J. W. F. Valle

We consider a very weakly interacting KeV majoron as dark matter particle (DMP), which provides both the critical density $ρ_{cr} = 1.88 \times 10^{-29} h^{2}$ $g/cm^{3}$ and the galactic scale $M_{gal}$ $\sim m^{3}_{Pl}/m^{2}_{J} \sim 10^{12} M_{\odot} (m_{J}/1 KeV)^{-2}$ for galaxy formation. The majoron couples to leptons only through some new "direct

R. Vogt, B. V. Jacak, P. L. McGaughey, P. V. Ruuskanen

It has been predicted that dilepton production may be used as a quark-gluon plasma probe. We calculate the rapidity distributions of thermal dileptons produced by an evolving quark-gluon plasma assuming a longitudinal scaling expansion with initial conditions locally determined from the hadronic rapidity density. These distributions are compared with Drell-Y

C. S. Kim, Jungil Lee, H. S. Song

We investigate the sensitivity of total cross sections of $e+p \rightarrow W,Z$ to CP-conserving non-standard $WWγ$ couplings. We include all the important production mechanisms and study the dependence of the total $W$ cross sections on the anomalous $WWγ$ couplings, $κ$ and $λ$. We argue that the ratio of $W$ and $Z$ production cross sections is particular

Oleg A. Fonarev

A new definition of the Wigner function for quantum fields coupled to curved space--time and an external Yang--Mills field is studied on the example of a scalar and a Dirac fields. The definition uses the formalism of the tangent bundles and is explicitly covariant and gauge invariant. Derivation of collisionless quantum kinetic equations is carried out for

Jorge Pullin

Table of contents: Editorial 1 Correspondents 3 Some recent work in general relativistic Astrophysics 4 Two dimensional black holes 6 Resonant-mass gravitational wave detectors: an update 8 Universality and scaling in gravitational collapse 9 Gravitational Wave memories upgraded 11 Conference report: quantum aspects of black holes 13 Conference report: knots

Steven Carlip

In contrast to other approaches to (2+1)-dimensional quantum gravity, the Wheeler-DeWitt equation appears to be too complicated to solve explicitly, even for simple spacetime topologies. Nevertheless, it is possible to obtain a good deal of information about solutions and their interpretation. In particular, strong evidence is presented that Wheeler-DeWitt q

E. J. Kerins, B. J. Carr

Brown dwarfs, stars with insufficient mass to burn hydrogen, could contribute to the dark matter in the Galactic disk, galactic halos or even a background critical density. We consider the detectability of such brown dwarfs in various scenarios, extending previous work by allowing for the possibility that they may have an extended mass spectrum or be clumped

Kirti Joshi

In the note we construct a family of étale coverings of the affine line. More specifically, let $F$ be a finite field of characteristic $p$ and suppose that the cardinality of $F$ is at least 4. Let $A = F[T]$ be the polynomial ring in one variable $T$, $K=F(T)$. Let $K_\infty$ be the completion of $K$ along the valuation given by $1/T$, and let $C$ be the c

Olivier Debarre

We prove a connexity theorem for abelian varieties in characteristic $0$: if $X$ is an abelian variety and $V\rightarrow X$ and $W\rightarrow X$ two morphisms, then, under certain hypotheses, the fiber product of $V$ and $W$ over $X$ is connected. This theorem has several consequences: the algebraic fundamental groups of a simple abelian variety $X$ and of a

M. H. Ernst, H. J. Bussemaker

Violation of (semi)-detailed balance conditions in lattice gas automata gives rise to unstable spatial fluctuations that lead to phase separation and pattern formation in spinodal decomposition, unstable propagating modes, driven diffusive systems and unstable uniform flows.

Costas G. Papadopoulos

Recursion relations for integrals of amplitudes over the phase space, i.e. for partial wave amplitudes, are introduced. In their simplest form these integrals are proportional to the s-wave amplitudes and represent rigorous lower bounds on the total cross sections. The connection with classical field equations in $D$ dimensions is established. Previous resul

Yadin Y. Goldschmidt

In this paper we give a closed form expression for the $1/d$ corrections to the self-energy characterizing the correction function of a manifold in random media. This amounts to the first correction beyond the variational approximation. At this time we were able to evaluate this corrections in the high temperature ``phase'' of the notorious toy-model

S. Kalyana Rama

The $d = 2$ string admits a black hole solution and also a singular solution when tachyon back reaction is included. It is of importance to know if the former solution can evolve into a later one. An explicit solution describing this process is difficult to obtain. We present here a scenario in which such an evolution is very likely to occur. In essence, it

Dimitri Alekseevsky, Peter W. Michor

An action of a Lie algebra $\frak g$ on a manifold $M$ is just a Lie algebra homomorphism $ζ:\frak g\to \frak X(M)$. We define orbits for such an action. In general the space of orbits $M/\frak g$ is not a manifold and even has a bad topology. Nevertheless for a $\frak g$-manifold with equidimensional orbits we treat such notions as connection, curvature, co

I. A. Batalin, I. V. Tyutin

The multilevel geometrically--covariant generalization of the field--antifield BV--formalism is suggested. The structure of quantum generating equations and hypergauge conditions is studied in details. The multilevel formalism is established to be physically--equivalent to the standard BV--version.

Malte Henkel, Gunter Schütz

Boundary conditions may change the phase diagram of non-equilibrium statistical systems like the one-dimensional asymmetric simple exclusion process with and without particle number conservation. Using the quantum Hamiltonian approach, the model is mapped onto an XXZ quantum chain and solved using the Bethe ansatz. This system is related to a two-dimensional

C. J. Fewster

A new construction is presented for point interactions (PI) and generalised point interactions (GPI). The construction is an inverse scattering procedure, using integral transforms suggested by the required scattering theory. The usual class of PI in 3 dimensions (i.e. the self adjoint extensions of the Laplacian on the domain of smooth functions compactly s

C. Gomez, G. Sierra

The study of the integrability properties of the N=2 Landau- Ginzburg models leads naturally to a graph generalization of the Yang-Baxter equation which synthetizes the well known vertex and RSOS Yang-Baxter equations. A non trivial solution of this equation is found for the $t_2$ perturbation of the A-models, which turns out to be intimately related to the

Shinobu Hikami

The saddle point equation described by the eigenvalues of N by N Hermitian matrices is analized for a finite N case and the scaling relation for the large N is considered. The critical point and the critical exponents of matrix model are obtained by the finite N scaling. One matrix model and two matrix model are studied in detail. Small N behavior for n-Isin

Robert Marnelius

Recent results of BRST quantization on inner product spaces are reviewed. It is shown how relativistic particle models may be quantized with finite norms and that the relation between the operator method and the conventional path integral treatments is nontrivial.

Robert Marnelius

Recent formal solutions of BRST quantization on inner product spaces within the operator method are shown to lead to an unexpected interpretation of the conventional path integral formulation. The relation between the Hamiltonians in the two formulations is nontrivial. For the operator method the correspondence requires certain quantum rules which make the f

Robert Marnelius

Recently derived general formal solutions of a BRST quantization on inner product spaces of irreducible Lie group gauge theories are applied to trivial models and relativistic particle models for particles with spin 0, 1/2 and 1. In the process general quantization rules are discovered which make the formal solutions exact. The treatment also give evidence t

Z. Maassarani

The critical Boltzmann weights for lattice analogues of the $N=2$ superconformal coset models $\frac{G_1 \times SO(dim(G/H))}{H}$ were given in \cite{nick}. In this paper Bethe Ansatz methods are employed to calculate the spectrum of the transfer matrix obtained from these Boltzmann weights. {}From this the central charge and conformal weights are obtained b