June 1995 arXiv papers — page 9

Scott Thomas

The possibility that both the baryon asymmetry and dark matter arise from the late decay of a population of supersymmetric particles is considered. If the decay takes place below the LSP freeze out temperature, a nonthermal distribution of LSPs results. With conserved $R$ parity these relic LSPs contribute to the dark matter density. A net asymmetry can exis

Richard W. Haymaker

The spacial distribution of fields and currents in confining theories can give direct evidence of dual superconductivity. We would like to discuss the techniques for finding these properties and calculating the superconductivity parameters in lattice simulations. We have seen dual Abrikosov vortices directly in pure U(1) and SU(2) and others have also seen t

Tanya Kurosky, J. M. Deutsch

We devise a method for designing materials that will have some desired structural characteristics. We apply it to multiblock copolymers that have two different types of monomers, A and B. We show how to determine what sequence of A's and B's should be synthesised in order to give a particular structure and morphology. %For example in a melt of such %

S. Q. Murphy, J. P. Eisenstein, L. N. Pfeiffer, K. W. West

For electrons tunneling between parallel two-dimensional electron systems, conservation of in-plane momentum produces sharply resonant current-voltage characteristics and provides a uniquely sensitive probe of the underlying electronic spectral functions. We report here the application of this technique to accurate measurements of the temperature dependence

Jarek Luberek, Goran Wendin

We calculate the x-ray absorption near edge structure (XANES) modulating the Ba 4d-photoabsorption cross section - the giant dipole resonance - centered around 110 eV photon energy for several models of spherical and non-spherical Ba@C_n metallofullerene cage systems. In the cases considered, the XANES interference patterns provide clear structural "fing

Daijiro Yoshioka

(BEDT-TTF)$_2$MHg(SCN)$_4$[M:K,Rb,Tl] shows typical two-dimensional angular dependent magnetoresistance oscillation (ADMRO) at high temperature (T$>$8K), but at lower temperature it shows anomalously large magnetoresistance, and the ADMRO pattern changes. These low temperature behaviors are explained as effects of a periodic potential. The present explanatio

L. S. Borkowski, P. J. Hirschfeld, W. O. Putikka

Superconducting states with "extended s-wave" symmetry have been suggested in connection with recent ARPES experiments on BSCCO. In the presence of impurities, thermodynamic properties of such states reflect a residual density of states $N(0)$ for a range of concentrations. While properties reflecting $N(ω)$ alone will be similar to those of d-wave s

Editors, :, Matthew Stone, Libby Levison

Short abstracts by computational linguistics researchers at the University of Pennsylvania describing ongoing individual and joint projects.

Keith M. Ashman, Alberto Conti, Stephen E. Zepf

We investigate the universality of the globular cluster luminosity function (GCLF) and the use of this function as an extragalactic distance indicator. Previous studies have found an offset between GCLF distances and those obtained with other techniques. We show that this offset can be understood in terms of a metallicity effect. Specifically, the globular c

Jeremy Goodman

The universe is nearly isotropic on very large scales. It is much more difficult to show that the universe is radially homogeneous (independent of distance), or equivalently, that it is isotropic about distant points. This taken as an axiom, since if it were not true, then we would occupy a preferred position. This paper considers several empirical arguments

A. Del Popolo, M. Gambera

We show how the results given by several authors relatively to the mass of a density peak are changed when small scale substructure induced by dynamical friction are taken into account. The peak mass obtained is compared to the result of Peacock \& Heavens (1990) and to the peak mass when dynamical friction is absent to show how these effects conspire to red

Thomas Lehmann, Bo Reipurth, Wolfgang Brandner

We have observed an outburst of the T Tauri star EX Lup in March 1994. We present both photometric (BVR) and spectroscopic (low and medium resolution) observations carried out during the decline after outburst. The star appears much bluer during outburst due to an increased emission of a hot continuum. This is accompanied by a strong increase of the veiling

C. Megan Urry, Paolo Padovani

The appearance of active galactic nuclei (AGN) depends so strongly on orientation that our current classification schemes are dominated by random pointing directions instead of more interesting physical properties. Light from the centers of many AGN is obscured by optically thick circumnuclear matter and in radio-loud AGN, bipolar jets emanating from the nuc

Norbert Scheu

We suggest to compute structure functions in the Hamiltonian formalism on a momentum lattice using a physically motivated regularisation that links the total parton number to the lattice size. We show for the $ϕ^4 _4$ theory that our method allows to describe continuum physics. The critical line and the renormalised mass spectrum close to that critical line

Simone Teufel

Many different tagsets are used in existing corpora; these tagsets vary according to the objectives of specific projects (which may be as far apart as robust parsing vs. spelling correction). In many situations, however, one would like to have uniform access to the linguistic information encoded in corpus annotations without having to know the classification

Cheuk-Yin Wong

The experimental ratio of $ψ'$ to $J/ψ$ is approximately a constant in $pA$ collisions, but decreases as the transverse energy increases in nucleus-nucleus collisions. These peculiar features can be explained as arising from approximately the same $c \bar c$-baryon absorption cross section for $ψ'$ and $J/ψ$ but greater disruption probabilities for $

J. Helgesson, T. Csorgo, M. Asakawa, B. Lorstad

Competition among particle evaporation, temperature gradient and flow is investigated in a phenomenological manner, based on a simultaneous analysis of quantum statistical correlations and momentum distributions for a non-relativistic, spherically symmetric, three-dimensionally expanding, finite source. The parameters of the model emission function are const

Nicola Manini, Erio Tosatti

We compute the vibronic spectrum of gas phase fullerene negative ions C_{60}^{-} and C_{60}^{2-}. We treat accurately the linear dynamical Jahn-Teller of these ions in their ground state. In particular, coupling of the t_{1u} orbital to the eight H_g vibrational modes is handled by exact diagonalizations including up to six vibrons. The resulting spectrum is

Hidetoshi Awata, Satoru Odake, Jun'ichi Shiraishi

Multiple-integral representations of the (skew-)Macdonald symmetric functions are obtained. Some bosonization schemes for the integral representations are also constructed.

S. W. Hawking, Simon F. Ross

We discuss the pair creation of black holes by the breaking of a cosmic string. We obtain an instanton describing this process from the $C$ metric, and calculate its probability. This is very low for the strings that have been suggested for galaxy formation.

Kenichi Horie

In several unified field theories the torsion trace is set equal to the electromagnetic potential. Using fibre bundle techniques we show that this is no leading principle but a formal consequence of another geometric relation between space-time and electromagentism.

J. Ellis, D. A. Ross

We investigate the cross-section for the production of a low-mass colour-singlet cluster in $e^+e^-$ annihilation with a large rapidity gap between the colour-singlet cluster and the other jets. It is argued that such events are the cross-channel analogue of large-rapidity-gap events in deep-inelastic scattering, and therefore could in principle be used to i

O. Coussaert, M. Henneaux, P. van Driel

Liouville theory is shown to describe the asymptotic dynamics of three-dimensional Einstein gravity with a negative cosmological constant. This is because (i) Chern-Simons theory with a gauge group $SL(2,R) \times SL(2,R)$ on a space-time with a cylindrical boundary is equivalent to the non-chiral $SL(2,R)$ WZW model; and (ii) the anti-de Sitter boundary con

D. C. Cabra, G. L. Rossini

We give explicit field theoretical representations for the observables of 2+1 dimensional Chern-Simons theory in terms of gauge invariant composites of 2D WZW fields. To test our identification we compute some basic Wilson loop correlators reobtaining known results.

Tsuneo Suzuki

This is the short review of Monte-Carlo studies of quark confinement in lattice QCD. After abelian projections both in the maximally abelian and Polyakov gauges, it is seen that the monopole part alone is responsible for confinement. A block spin transformation on the dual lattice suggests that lattice $SU(2)$ QCD is always ( for all $β$) in the monopole con

S. Chaudhuri, J. Polchinski

We discuss an orbifold of the toroidally compactified heterotic string which gives a global reduction of the dimension of the moduli space while preserving the supersymmetry. This construction yields the moduli space of the first of a series of reduced rank theories with maximal supersymmetry discovered recently by Chaudhuri, Hockney, and Lykken. Such moduli

Ognyan Stoyanov

We study the problem of classifying all Poisson-Lie structures on the group $G_{\infty}$ of formal diffeomorphisms of the real line $\zR^{1}$ which leave the origin fixed, as well as the extended group of diffeomorphisms $G_{0\infty}\supset G_{\infty}$ whose action on $\zR^{1}$ does not necessarily fix the origin. A complete local classification of all Poiss

Boris Kupershmidt, Ognyan Stoyanov

A local classification of all Poisson-Lie structures on an infinite-dimensional group $G_{\infty}$ of formal power series is given. All Lie bialgebra structures on the Lie algebra ${\Cal G}_{\infty}$ of $G_{\infty}$ are also classified.

E. Bender, K. W. Schmid, Amand~Faessler

A multi-configuration mixing approach built on essentially complex, symmetry-projected Hartree-Fock-Bogoliubov (HFB) mean fields is introduced. The mean fields are obtained by variation after projection. The configuration space consists out of the symmetry-projected HFB vacuum and the symmetry-projected two-quasiparticle excitations for even, and the symmetr

R. A. Arndt, I. I. Strakovsky, R. L. Workman

We reexamine Chew's method for extracting the $πNN$ coupling constant from np differential cross section measurements. Values for this coupling are extracted below 350 MeV, in the potential model region, and up to 1 GeV. The analyses to 1~GeV have utilized 55 data sets. We compare these results to those obtained via $χ^2$ mapping techniques. We find that

I. I. Mazin, Ronald E. Cohen

Electronic structure calculations for compressed molecular hydrogen are performed to provide more insight into the diversity of phenomena recently observed experimentally. We perform full-potential LAPW calculations and analyze them in terms of a molecular tight-binding model. We show that $σ_g$ and $σ_u$ bands overlap occurs at rather low pressure, while an

Greg Kuperberg

In previous paper, the author applied the permanent-determinant method of Kasteleyn and its non-bipartite generalization, the Hafnian-Pfaffian method, to obtain a determinant or a Pfaffian that enumerates each of the ten symmetry classes of plane partitions. After a cosmetic generalization of the Kasteleyn method, we identify the matrices in the four determi

Haim Goldberg

Supersymmetry breaking may be linked to the formation of gaugino condensates in a hidden sector. In this work, the process of formation of the condensate is examined in a cosmological context, using an effective field theory of the gaugino bilinear which provides a reasonable interpolation between the high- and low-temperature phases. The implementation of a

Ralf Kerschner

A critically discerning discussion of path integral bosonization is given. Successively evaluating the conventional path integral bosonization of QCD it is shown without any approximations that gluons must be composed of two quarks. This contradicts the fundamentals of QCD, where quarks and gluons are independent fields. Furthermore, bosonizing the Fierz reo

Vasily E. Tarasov

Noncritical strings in the "coupling constant" phase space and bosonic string in the affine-metric curved space are dissipative systems. But the quantum descriptions of the dissipative systems have well known ambiguities. We suggest some approach to solve the problems of this description. The generalized Poisson algebra for dissipative systems is con

G W Gibbons, N S Manton

The Lagrangian for the motion of $n$ well-separated BPS monopoles is calculated, by treating the monopoles as point particles with magnetic, electric and scalar charges. It can be reinterpreted as the Lagrangian for geodesic motion on the asymptotic region of the $n$-monopole moduli space, thereby determining the asymptotic metric on the moduli space. The me

A. Casher, V. Elkonin, Y. Shamir

We show that instantons violate a supersymmetric identity in a classically supersymmetric Higgs model with no massless fermions. This anomalous breaking arises because the correct perturbative expansion in the instanton sector is not supersymmetric. The attempt to construct a manifestly supersymmetric expansion generates infra-red divergences.

M. E. X. Guimarães, L. A. J. London

In this article we consider $SU(2)$ Chern-Simons/Higgs theory coupled to gravity in three-dimensions. It is shown that for a cylindrically symmetric vortex both the Einstein equations and the field equations can be reduced to a set of first-order Bogomol'nyi equations provided that we choose a specific eighth-order potential.

Robert Carroll, Boris Konopelchenko

Basic quantities related to 2-D gravity, such as Polyakov extrinsic action, Nambu-Goto action, geometrical action, and Euler characteristic are studied using generalized Weierstrass-Enneper (GWE) inducing of surfaces. Connection of the GWE inducing with conformal immersion is made and varius aspects of the theory are shown to be invariant under the modified

Jin Dai, Roger Dashen, Elizabeth Jenkins, Aneesh V. Manohar

The breaking of flavor SU(3) symmetry in the axial couplings and magnetic moments of baryons is analyzed in the $1/N_c$ expansion. A simple meson loop graph which is known to be of order $\sqrt{m_s}$ and leading order in $1/N_c$ correctly predicts the pattern of symmetry breaking in the magnetic moments. It is, however, not possible to use this graph to pred

W. Grimus, M. N. Rebelo

We study the possibilities to define CP and parity in general gauge theories by utilizing the intimate connection of these discrete symmetries with the group of automorphisms of the gauge Lie algebra. Special emphasis is put on the scalar gauge interactions and the CP invariance of the Yukawa couplings.

Ken Kiers, Shmuel Nussinov, Nathan Weiss

We study the effect of coherent and incoherent broadening on neutrino oscillations both in vacuum and in the presence of matter (the MSW effect). We show under very general assumptions that it is not possible to distinguish experimentally neutrinos produced in some region of space as wave packets from those produced in the same region of space as plane waves

Yu. S. Kalashnikova, Yu. B. Yufryakov

The model for constituent glue is presented starting from the perturbation theory in nonperturbative QCD vacuum. Green function is constructed for a system containing qqbar pair and gluon propagating in the vacuum background field, and Hamiltonian approach to the problem is formulated. The masses of lowest qqbarg hybrids with light quarks are evaluated, and

I. N. Nikitin

A problem of density matrix determination in terms of the given angular distribution of decay products is considered.

I. N. Nikitin

A problem of amplitude reconstruction in terms of the given angular distribution is considered. Solution of this problem is not unique. A class of amplitudes, correspondent to one and the same angular distribution, forms a region in projection onto a finite set of spherical harmonics. An explicit parametrization of a boundary of the region is obtained. A sha

Kurt Langfeld, Mannque Rho

On the level of an effective quark theory, we define confinement by the absence of quark anti-quark thresholds in correlation functions. We then propose a confining Nambu-Jona-Lasinio-type model. The confinement is implemented in analogy to Anderson localization in condensed matter systems. We study the model's phase structure as well as its behavior und

Gunnar S. Bali, Klaus Schilling, Armin Wachter

We present results on the spin-independent quark-antiquark potential in SU(3) gauge theory from a simulation on a 48^3*64 lattice at Beta = 6.8, corresponding to a volume of (1.7 fm)^3. Moreover, a comprehensive analysis of spin- and velocity-dependent potentials is carried out for SU(2) gauge theory, with emphasis on the short range structure, on lattices w

H. Hayashii, TOPAZ collaboration

Jet production in $γγ$ collisions have been studied with a jet-cone algorithm using a 233 $pb^{-1}$ data taken by the TOPAZ detector at the TRISTAN $e^+e^-$ collider. The transverse momentum dependence of the jet-cross section as well as accompanying activities in the small-angle region show the direct evidence for the resolved photon processes. We also pres

Fintan D. Ryan

The effect of gravitational radiation reaction on circular orbits around a spinning (Kerr) black hole is computed to leading order in $S$ (the magnitude of the spin angular momentum of the hole) and in the strength of gravity $M/r$ (where $M$ is the mass of the black hole, $r$ is the orbital radius, and $G=c=1$). The radiation reaction makes the orbit shrink

Lawrence E. Kidder

We examine the effects of spin-orbit and spin-spin coupling on the inspiral of a coalescing binary system of spinning compact objects and on the gravitational radiation emitted therefrom. Using a formalism developed by Blanchet, Damour, and Iyer, we calculate the contributions due to the spins of the bodies to the symmetric trace-free radiative multipole mom

O. Obregón, J. Socorro

We find solutions for quantum Class A Bianchi models of the form $\rm Ψ=W e^{\pm Φ}$ generalizing the results obtained by Moncrief and Ryan in standard quantum cosmology. For the II and IX Bianchi models there are other solutions $\rm \tildeΦ_2$, $\rm \tildeΦ_9$ to the Hamilton-Jacobi equation for which $\rm Ψ$ is necessarely zero, in contrast with solutions

Takashi Torii, Kei-ichi Maeda, Takashi Tachizawa

We present spherically symmetric static solutions (a particle-like solution and a black hole solution) in the Einstein-Yang-Mills system with a cosmological constant.Although their gravitational structures are locally similar to those of the Bartnik-McKinnon particles or the colored black holes, the asymptotic behavior becomes quite different because of the

S. M. Salamon

The topology of the smooth moduli space of stable rank 2 bundles over a Riemann surface of genus 3 is related to that of the real Grassmannian Gr_4(R^8).

Stefan Scheidl

A theory for surface transitions in the presence of a disordered pinning potential is presented. Arbitrary disorder correlations are treated in the framework of a dynamical functional renormalization group. The roughening transition, where surface roughness and mobility behave discontinuously, is shown to turn smoothly into the continuous superroughening tra

T. H. Stoof, Yu. V. Nazarov

We theoretically investigate time-dependent resonant tunneling via two discrete states in an experimentally relevant setup. Our results show that the dc transport through the system can be controled by applying irradiation with a frequency which matches the energy difference between the discrete states. We predict resonant phenomena which should be easily ob

T. H. Stoof, Gerrit E. W. Bauer

We study the competition between the exchange and the direct Coulomb interaction near the edge of a two-dimensional electron gas in a strong magnetic field using density-functional theory in a local approximation for the exchange-energy functional. Exchange is shown to play a significant role in reducing the spatial extent of the compressible edge channel re

P. L. Krapivsky, E. Ben-Naim

Aggregation processes with an arbitrary number of conserved quantities are investigated. On the mean-field level, an exact solution for the size distribution is obtained. The asymptotic form of this solution exhibits nontrivial ``double'' scaling. While processes with one conserved quantity are governed by a single scale, processes with multiple cons

Sam Bayer, Mark Johnson

This paper compares the consistency-based account of agreement phenomena in `unification-based' grammars with an implication-based account based on a simple feature extension to Lambek Categorial Grammar (LCG). We show that the LCG treatment accounts for constructions that have been recognized as problematic for `unification-based' treatments.

John Hughes, Clive Souter, Eric Atwell

This paper describes some of the recent work of project AMALGAM (automatic mapping among lexico-grammatical annotation models). We are investigating ways to map between the leading corpus annotation schemes in order to improve their resuability. Collation of all the included corpora into a single large annotated corpus will provide a more detailed language m

A. M. Read, T. J. Ponman

Using data from the ROSAT Wide Field Camera all-sky survey, we have established upper limits to the extreme ultraviolet (EUV) flux from a sample of 30 bright, nearby, non-active spiral galaxies. These galaxies were chosen to be those most likely to be detected in the EUV on the basis of (i) low interstellar absorption within our own galaxy, (ii) brightness i

R. K. Schaefer, S. Ali, M. Limon, L. Piccirillo

We have used the data from the COBE satellite to search for delayed microwave emission (31 - 90 GHz) from Gamma Ray Bursts (GRBs). The large $7^\circ$ beam of COBE is well matched to the large positional uncertainties in the GRB locations, although it also means that fluxes from (point source) GRB objects will be diluted. In view of this we are doing a stati

M. Jaroszynski

We investigate the configurations consisting of massive, dense and hot tori around stellar mass Kerr black holes as possible sources of energy for the gamma ray bursts in cosmological hypothesis of their origin. We limit parameters of our models to the values resulting from neutron stars merger calculations or suggested in the ``failed supernova'' sc

Adam Burrows, John Hayes, Bruce Fryxell

We investigate in this paper the core-collapse supernova explosion mechanism in both one and two dimensions. We verify the usefulness of neutrino-driven overturn (``convection'') between the shock and the neutrinosphere in igniting the supernova explosion. The 2-D simulation of the core of a 15$\mdot$ star that we present here indicates that the brea

Adam Burrows anbd John Hayes

Fresh insights and powerful numerical tools are revitalizing the theoretical exploration of the supernova mechanism. The realization that the protoneutron star is Rayleigh-Taylor unstable at various times and radii and, hence, that a multi-dimensional perspective is required is one agent of this revolution. However, a new physical understanding of the nature

Adam Burrows, Jim Liebert

Recent novel observations have probed the baryonic fraction of the galactic dark matter that has eluded astronomers for decades. Late in 1993, the MACHO and EROS collaborations announced in this journal the detection of transient and achromatic brightenings of a handful of stars in the Large Magellanic Cloud that are best interpreted as gravitational microle

Adam Burrows, Ken Van Riper

We have performed Monte Carlo calculations of gamma-ray transport in models of the clumpy debris cloud of the LMC supernova, SN1987A, to study the influence of composition mixing and heterogeneity on its emergent gamma-ray and X-ray fluxes. In particular, we have focused on the problematic Ginga band (16 -- 28 keV) flux at day 600, whose measured value was a

Adam Burrows, John Hayes

It is now believed that pulsars comprise the fastest population of stars in the galaxy. With inferred mean, root-mean-square, and maximum 3-D pulsar speeds of $\sim$300-500 km/s, $\sim$500 km/s, and $\sim$2000 km/s, respectively, the question of the origin of such singular proper motions becomes acute. What mechanism can account for speeds that range from ze

Keiichi Wada, Asao Habe

We have found an effective fueling process to a central region of galaxies with weak bar-like distortion by two dimensional hydrodynamical simulations. Gravitational instability of an elongated gas ring at the inner Lindblad resonance (ILR), which has been reported as an effective fueling mechanism, are not needed for this fueling process. A massive gaseous

A. Burrows, D. Saumon, T. Guillot, W. B. Hubbard

Interest among astronomers in the detection of extra-solar planets is accelerating with the growing realization that it may soon be technically feasible. The ongoing renaissance in telescope construction and the anticipated launches of new space platforms are encouraging many scientists to review and improve the means by which planets can be discovered. The

Yuhai Tu, John Toner

We propose a non-equilibrium continuum dynamical model for the collective motion of large groups of biological organisms (e.g., flocks of birds, slime molds, etc.) Our model becomes highly non-trivial, and different from the equilibrium model, for $d<d_c=4$; nonetheless, we are able to determine its scaling exponents {\it exactly} in $d=2$, and show that, un

James S. Ball, Anthony Pantziris

Old models of the scattering of composite systems based on the Glauber model of multiple diffraction are applied to hadron-nucleus scattering. We obtain an excellent fit with only two free parameters to the highest energy hadron-nucleus data available. Because of the quality of the fit and the simplicity of the model it is argued that it should continue to b

Don N. Page

Quantum mechanics may be formulated as Sensible Quantum Mechanics (SQM) so that it contains nothing probabilistic, except, in a certain frequency sense, conscious perceptions. Sets of these perceptions can be deterministically realized with measures given by expectation values of positive-operator-valued awareness operators in a quantum state of the universe

Janna J. Levin

The union of high-energy particle theories and gravitation often gives rise to an evolving strength of gravity. The standard picture of the earliest universe would certainly deserve revision if the Planck mass, which defines the strength of gravity, varied. A notable consequence is a gravity-driven, kinetic inflation. Unlike standard inflation, there is no p

Enrico Meggiolaro

In this paper we calculate the high--energy quark--quark scattering amplitude, first in the case of scalar QCD, using Fradkin&#39;s approach to derive the scalar quark propagator in an external gluon field and computing it in the eikonal approximation. (This approach was also recently used by Fabbrichesi, Pettorino, Veneziano and Vilkovisky to study the four

T. Padmanabhan, Renyue Cen, Jeremiah P. Ostriker, F J Summers

The nonlinear clustering of dark matter particles in an expanding universe is usually studied by N-body simulations. One can gain some insight into this complex problem if simple relations between physical quantities in the linear and nonlinear regimes can be extracted from the results of N-body simulations. Hamilton et al. (1991) and Nityananda and Padmanab

Ansar Fayyazuddin, Dingping Li

The Lowest Landau Level on a torus is studied. The dimension of the many-body Hilbert space is obtained and is found to be different from the formula given by Haldane. Our result can be tested in numerical investigations of the low-energy spectrum of fractional quantum Hall states on a torus.

Sergei V. Zenkin

We define Weyl fermions on a finite lattice in such a way that in the path integral the action is gauge invariant but the functional measure is not. Two variants of such a formulation are tested in perturbative calculation of the fermion determinant in chiral Schwinger model. We find that one of these variants ensures restoring the gauge invariance of the no

J. S. Dowker

Techniques are presented for calculating directly the scalar functional determinant on the Euclidean d-ball. General formulae are given for Dirichlet and Robin boundary conditions. The method involves a large mass asymptotic limit which is carried out in detail for d=2 and d=4 incidentally producing some specific summations and identities. Extensive use is m

Andrzej Czarnecki, Bernd Krause, William J. Marciano

The two-loop electroweak corrections to the anomalous magnetic moment of the muon, generated by fermionic loops, are calculated. An interesting role of the top quark in the anomaly cancellation is observed. New corrections, including terms of order $G_\mu \alpha m_t^2$, are computed and a class of diagrams previously thought to vanish are found to be importa

Anindya K. Biswas, Alok Kumar, Koushik Ray

We study the symmetries of the two dimensional Heterotic string theory by following the approach of Kinnersley et al for the study of stationary-axially symmetric Einstein-Maxwell equations. We identify the finite dimensional groups $G&#39;$ and $H&#39;$ for the Einstein-Maxwell equations. We also give the constructions for the infinite number of conserved c

Kazuhiro Hikami

The integrable system is introduced based on the Poisson $ rs $-matrix structure. This is a generalization of the Gaudin magnet, and in SL(2) case isomorphic to the generalized Neumann model. The separation of variables is discussed for both classical and quantum case.

Robert Bluhm, Alan Kostelecky

This paper begins with an examination of the revival structure and long-term evolution of Rydberg wave packets for hydrogen. We show that after the initial cycle of collapse and fractional/full revivals, which occurs on the time scale $t_{\rm rev}$, a new sequence of revivals begins. We find that the structure of the new revivals is different from that of th

Michael Martin Nieto, D. Rodney Truax

For use in calculating higher-order coherent- and squeezed- state quantities, we derive generalized generating functions for the Hermite polynomials. They are given by $\sum_{n=0}^{\infty}z^{jn+k}H_{jn+k}(x)/(jn+k)!$, for arbitrary integers $j\geq 1$ and $k\geq 0$. Along the way, the sums with the Hermite polynomials replaced by unity are also obtained. We a

Marc-Thierry Jaekel, Serge Reynaud

Quantum fluctuations impose fundamental limits on measurement and space-time probing. Although using optimised probe fields can allow to push sensitivity in a position measurement beyond the &#34;standard quantum limit&#34;, quantum fluctuations of the probe field still result in limitations which are determined by irreducible dissipation mechanisms. Fluctua

Marc-Thierry Jaekel, Serge Reynaud

Vacuum field fluctuations exert a radiation pressure which induces mechanical effects on scatterers. The question naturally arises whether the energy of vacuum fluctuations gives rise to inertia and gravitation in agreement with the general principles of mechanics. As a new approach to this question, we discuss the mechanical effects of quantum field fluctua

Marc-Thierry Jaekel, Serge Reynaud

As revealed by space-time probing, mechanics and field theory come out as complementary descriptions for motions in space-time. In particular, quantum fields exert a radiation pressure on scatterers which results in mechanical effects that persist in vacuum. They include mean forces due to quantum field fluctuations, like Casimir forces, but also fluctuation

Hiroyuki Fujita, Sh. M. Shvartsman

Two-dimensional heavy-quark QCD is studied in the light-cone coordinates with (anti-) periodic field boundary conditions. We carry out the light-cone quantization of this gauge invariant model. To examine the role of the zero modes of the gauge degrees of freedom, we consider the quantization procedure in the zero mode and the nonzero mode sectors separately

Ram Brustein

I present an outline for cosmological evolution in the framework of string theory with emphasis on a phase of dilaton-driven kinetic inflation. It is shown that a typical background of stochastic gravitational radiation is generated, with strength that may allow its detection in future gravity wave experiments.

Bruno IOCHUM, Daniel KASTLER, Thomas SCHÜCKER

The non-commutative approach of the standard model produces a relation between the top and the Higgs masses. We show that, for a given top mass, the Higgs mass is constrained to lie in an interval. The length of this interval is of the order of $m_τ^2/m_t$.

J. Madore, J. Mourad

It is suggested that quantum fluctuations of the light cone are at the origin of what appears at low energy to be a higher-dimensional structure over space-time. A model is presented which has but a finite number of Yang-Mills fields although the supplementary algebraic structure is of infinite dimension.

Jean-Loup GERVAIS

The strong coupling physics of two dimensional gravity at $C=7$, $13$, $19$ is summarized. It is based on a new set of local fields which do not preserve chirality. Thus this quantum number becomes ``deconfined&#39;&#39; in the strongly coupled regime. This new set leads to a novel definition of the area elements, and hence to a modified expression for the s

Stephen Hwang, Henric Rhedin

WZNW models, especially gauged WZNW models, are important in the study of conformal field theories. Karabali and Schnitzer initiated the study of the BRST cohomology of a WZNW model gauged by an anomaly free vector sub-group and results were given for abelian sub-groups. This result was generalized to non-abelian sub-groups for a specific set of representati

Jin-Ho Cho, Hyuk-jae Lee

In the context of $ISO(2,1)$ gauge theory, we consider $(2+1)$-dimensional gravity with the gravitational Chern-Simons term (CST). This formulation allows the `exact&#39; solution for the system coupled to a massive point particle (which is not the case in the conventional Chern-Simons gravity). The solution exhibits locally trivial structure even with the C

Alan Kostelecky, Stuart Samuel

We present analytical solutions to the nonlinear equations describing the behavior of a gas of neutrinos with two flavors. Self-maintained coherent flavor oscillations are shown to occur when the gas density exceeds a critical value determined by the neutrino masses and the mean neutrino energy in the gas. Similar oscillations may have occurred in the early

K. S. Babu, S. M. Barr

It is shown that in realistic SUSY GUT models of quark and lepton masses both the proton decay rate and branching ratios differ in general from those predicted in the minimal $SU(5)$ supersymmetric model. The observation of proton decay, and in particular the branching ratio $B[(p \rightarrow π^+ \overlineν)/(p \rightarrow K^+ \overlineν)]$, would thus allow

R. Aleksan, F. Buccella, A. Le Yaouanc, L. Oliver

A major problem in the determination of the the CP angle $α$, that should be measured through modes of the type $B_d, \bar{B}_d \to ππ, \cdots ,$ is the uncertainty coming from Penguin diagrams. We consider the different ground state modes $ππ$, $πρ$, $ρρ$, and, assuming the FSI phases to be negligible, we investigate the amount of uncertainty coming from Pe

J. M. Butterworth, J. R. Forshaw, M. H. Seymour, J. K. Storrow

At $e^+e^-$ and $ep$ colliders, the large fluxes of almost on-shell photons accompanying the lepton beams lead to the photoproduction of jets. As the centre-of-mass energy is increased, regions of smaller $x$ in the parton densities are explored and these are regions of high parton density. As a result, the probability for more than one hard partonic scatter

G. Montagna, O. Nicrosini, F. Piccinini, L. Trentadue

A study of the radiative neutrino counting reaction $e^+ e^- \to ν{\bar ν} γ$ at LEP1 and LEP2 energies is presented. An approximate expression for the spectrum of the observed photon is derived within the framework of the $p_t$-dependent structure function approach. This is compared with an exact expression and found in agreement within the foreseen experim

K. Huber, H. Neufeld

Using the close relationship between the low--energy constants of chiral perturbation theory and the chiral invariant interactions of the vector meson resonances with the pseudoscalar mesons, we investigate the process $ρ^0 \ra π^+ π^- γ$. Compared with the contribution from the pure bremsstrahlung mechanism, we find an enhancement of the decay rate near the

J. -M. Gérard, T. Lahna

The Bjorken-Johnson-Low theorem applied to the $γ^\ast \to γ^\ast π^0$ process provides us with a rather remarkable asymptotic behaviour for the $π^0 γ^\ast γ^\ast$ vertex. We compare our result with previous QCD- inspired estimates and argue that the predicted behaviour is quite consistent with the present data on hadronic $J/Ψ$ decays and ensures the match