May 1995 arXiv papers — page 7

Nicolas Pavloff

We study the semiclassical quantization of an ensemble of billiards with a small random shape deformation. We derive a trace formula averaged over shape disorder. The results are illustrated by the study of supershells in rough metal clusters.

M. H. van Kerkwijk, J. van Paradijs, E. J. Zuiderwijk

We analyze the currently available observations of X-ray binaries in a consistent way, to re-determine the masses of the neutron stars in these systems. In particular, our attention is focussed on a realistic and consistent assessment of observational uncertainties and sources of systematic error. Confidence limits for these new mass estimates are generally

M. H. van Kerkwijk, J. van Paradijs, E. J. Zuiderwijk, G. Hammerschlag-Hensberge

We present new high-resolution, high signal-to-noise optical spectra of HD 77581, the optical counterpart of the X-ray source Vela X-1, and determine radial velocities from these spectra, as well as from high-resolution IUE spectra and from digitized photographic spectra. The measured velocities show strong deviations from a pure Keplerian radial-velocity cu

J. L. Cervantes-Cota, H. Dehnen

We are considering the cosmological consequences of an induced gravity theory coupled to the minimal standard model of particle physics. The non-minimal coupling parameter between gravity and the Higgs field must then be very large, yielding some new cosmological consequences for the early Universe and new constraints on the Higgs mass. As an outcome, new in

Christopher S. Kochanek

We use the Jaffe model as a global mass distribution for the Galaxy and determine the circular velocity $v_c$ and the Jaffe radius $r_j$ using the satellites of the Galaxy, estimates of the local escape velocity of stars, the constraints imposed by the known rotation curve of the disk, and the Local Group timing model. The models include the systematic uncer

Y. -N. Chin, C. Henkel, J. B. Whiteoak, N. Langer

A 12C32S, 13C32S, 12C34S, and 12C33S J = 2 - 1 line survey has been made to study interstellar 32S/34S and 34S/33S ratios from the galactic disk. The four CS isotopomers were detected in 20 star forming regions with galactocentric distances between 3 and 9 kpc. From a comparison of line velocities, the C33S J = 2 - 1 rest frequency is about 250 kHz below the

J. P. Ostriker, Paul J. Steinhardt

Observational constraints guide one forcefully to examine models in which the matter density is substantially less than critical density. Particularly noteworthy are those which are consistent with inflation. For these models, microwave background anisotropy, large-scale structure measurements, direct measurements of the Hubble constant, $H_0$, and the closu

Vyjayanthi Chari, Andrew Pressley

We study tensor products of fundamental representations of Yangians and show that the fundamental quotients of such tensor products are given by Dorey's rule.

Mauro Anselmino, Francisco Caruso, Eugene Levin

Some higher twist corrections to the Bjorken sum rule are estimated in the framework of a quark-diquark model of the nucleon. The parameters of the model have been previously fixed by fitting the measured higher twist corrections to the unpolarized structure function $F_2(x, Q^2)$. The resulting corrections to the Bjorken sum rule turn out to be negligible.

P. H. Chankowski, S. Pokorski

The LEP data and the measurement of $M_W$ confirm the electro weak symmetry breaking by the Higgs mechanism with (2--3)\% accuracy. For the Higgs boson mass, fits to the present data (without the SLD result) give $M_h=121^{+207}_{-118}$ GeV and $M_h<800$ GeV at 95\% C.L. We analyze those fits from the point of view of the impact of different measurements on

E. D. Moore

We consider the number of configurations of a surface in two dimensions that has a prescribed length and encloses a prescribed perimeter with respect to a baseline. An approximate analytical treatment in a semi--continuum compares favourably with results from an exact algorithm for the discrete lattice. This work is relevant for finding the entropy associate

K. A. Bronnikov

Exact static, spherically symmetric solutions to the Einstein-Abelian gauge-dilaton equations, in $D$-dimensional gravity with a chain of $n$ Ricci-flat internal spaces are considered, with the gauge field potential having three nonzero components: the temporal, Coulomb-like one, the one pointing to one of the extra dimensions, and the one responsible for a

Riccardo Guida, Kenichi Konishi, Hiroshi Suzuki

We improve and generalize in several accounts the recent rigorous proof of convergence of delta expansion - order dependent mappings (variational perturbation expansion) for the energy eigenvalues of anharmonic oscillator. For the single-well anharmonic oscillator the uniformity of convergence in $g\in[0,\infty]$ is proven. The convergence proof is extended

Atsushi Nakayashiki, Yasuhiko Yamada

The crystalline spinon basis for the RSOS models associated with $\widehat{sl_2}$ is studied. This basis gives fermionic type character formulas for the branching coefficients of the coset $(\widehat{sl_2})_l \times (\widehat{sl_2})_N/(\widehat{sl_2})_{l+N}$. In addition the path description of the parafermion characters is found as a limit of the spinon des

Christian Fronsdal

Lecture notes. Introduction to the cohomology of algebras, Lie algebras, Lie bialgebras and quantum groups. Contains a new derivation of the classification of classical r-matrices in terms of deformation cohomology, and a calculation of the esoteric forms of quantum gl(N) by deformation theory.

Peter Komjath, Saharon Shelah

It is consistent for every (1 <= n< omega) that (2^omega = omega_n) and there is a function (F:[omega_n]^{< omega}-> omega) such that every finite set can be written at most (2^n-1) ways as the union of two distinct monocolored sets. If GCH holds, for every such coloring there is a finite set that can be written at least (sum^n_{i=1}{n+i choose n}{n choose i

Martin Gilchrist, Saharon Shelah

Let kappa be an uncountable cardinal and the edges of a complete graph with kappa vertices be colored with aleph_0 colors. For kappa >2^{aleph_0} the Erdős-Rado theorem implies that there is an infinite monochromatic subgraph. However, if kappa <= 2^{aleph_0}, then it may be impossible to find a monochromatic triangle. This paper is concerned with the latter

Sakaé Fuchino, Sabine Koppelberg, Saharon Shelah

We study the determinacy of the game G_kappa (A) introduced in [FKSh:549] for uncountable regular kappa and several classes of partial orderings A. Among trees or Boolean algebras, we can always find an A such that G_kappa (A) is undetermined. For the class of linear orders, the existence of such A depends on the size of kappa^{< kappa}. In particular we obt

Mark Wexler

A perturbative technique, the low-temperature expansion, is developed for matrix models of random surfaces. It can be applied to models with arbitrary target spaces, including ones with c>1. As a simple illustration, the series is worked out to 10th order for the surface coupled to a q-state Potts model. Accurate estimates for, e.g., $γ_{str}$ are obtained b

Andre LeClair

It is known that classical electromagnetic radiation at a frequency in resonance with energy splittings of atoms in a dielectric medium can be described using the classical sine-Gordon equation. In this paper we quantize the electromagnetic field and compute quantum corrections to the classical results by using known results from the sine-Gordon quantum fiel

Bhashyam Balaji

We show that the present limit on the inclusive decay $b\rightarrow sγ$ provides strong constraints on Technicolor models. In particular, small values of $F_π$ and the mass of charged octet and singlet technipions are excluded, assuming the most natural form of the technipion coupling to the ordinary quarks.

Bhashyam Balaji

It is demonstrated that the extended technicolor model proposed recently by Appelquist and Terning has pair of potentially light $U(1)$ Goldstone bosons coupling to ordinary matter with strength $2m_f\over F_π$, where $m_f$ is the mass of the fermion and $F_π \approx 125\,\GeV$. These Goldstone bosons could get a mass if the spontaneously broken $U(1)$ symme

Konstantin Goulianos

Results of experiments probing the structure of the pomeron at hadron colliders and at HERA are reviewed. By renormalizing the pomeron flux factor in diffraction dissociation as dictated by unitarity, a picture emerges from the data in which the pomeron appears to be made of valence quark and gluon color-singlets in a combination suggested by asymptopia.

Wolfgang Kilian

The Higgs couplings to matter fields are proportional to their masses. Thus Higgs amplitudes can be obtained by differentiating amplitudes without Higgs with respect to masses. We show how this well-known statement can be extended to higher order when renormalization effects are taken into account. We establish the connection with the Callan-Symanzik and ren

Ulrike KRAEMMER, Anton K. REBHAN, Hermann SCHULZ

Hot scalar electrodynamics is adopted as a toy model for a hot gluon plasma to display some aspects of the compulsory resummation of hard thermal loops when next-to-leading order quantities at soft momentum scales are to be calculated. [Talk given by A.K.R. at a one-day meeting dedicated to the memory of Tanguy ALTHERR, held on November 4, 1994 at CERN, Gene

B. Ehrnsperger, A. Schäfer

We present an update of a phenomenological model for the spin dependent structure functions $g_1(x,Q^2)$ of the proton and neutron. This model is based on a broken SU(6) wavefunction parametrized by the unpolarized structure functions. The two free parameters of the model are choosen to fulfill the Bjorken and Ellis--Jaffe sum rules. The model respects isosp

R. Dahm, M. Kirchbach

The relevance of the contracted SU(4) group as a symmetry group of the pion nucleon scattering amplitudes in the large $N_c$ limit of QCD raises the problem on the construction of effective Lagrangians for SU(4) supermultiplets. In the present study we suggest effective Lagrangians for selfconjugate representations of SU(4) in exploiting isomorphism between

P. H. Chankowski, S. Pokorski

We present the results of a first global fit to the electroweak observables in the MSSM. The best fit selects either very low or very large values of ~$\tanβ$ ~and, correspondingly, chargino (higgsino--like) and stop or the ~$CP-$odd Higgs boson are within the reach of LEP 2. Moreover, the best fit gives ~ $α_s(M_Z)=0.118^{+0.005}_{-0.010}$, ~which is lower

H. Aihara

We present results from CDF and DØ on $Wγ$ and $Zγ$ productions in $p\bar{p}$ collisions at $\sqrt{s}=1.8~{\rm TeV}.$ The goal of the analyses is to test the non-abelian self-couplings of the $W$, $Z$ and photon, one of the most direct consequences of the $SU(2)_L\otimes U(1)_Y$ gauge symmetry. We present direct measurements of $WWγ$ couplings and limits on

K. A. Bronnikov, V. N. Melnikov

Vacuum static, axially symmetric space-times in $D$-dimensional general relativity with a Ricci-flat internal space are discussed. It is shown, in particular, that some of the monopole-type solutions are free of curvature singularities and their source can be a disk membrane bounded by a ring with a string or branching type singularity. Another possibility i

Paul Casper, Bruce Allen

We examine the rates at which energy and momentum are radiated into gravitational waves by a large set of realistic cosmic string loops. The string loops are generated by numerically evolving parent loops with different initial conditions forward in time until they self-intersect, fragmenting into two child loops. The fragmentation of the child loops is foll

Alan D. Rendall

The dynamics of solutions of the Einstein-Vlasov system with Bianchi I symmetry is discussed in the case of massive or massless particles. It is shown that in the case of massive particles the solutions are asymptotic to isotropic dust solutions at late times. The initial singularity is more difficult to analyse. It is shown that the asymptotic behaviour the

Daniel S. Freed

This is a note for the conference proceedings Topological and Geometrical Problems related to Quantum Field Theory. We summarize our joint work with Dai about eta invariants on manifolds with boundary. Then we apply these results to prove the curvature and holonomy formulas for the natural connection on the determinant line bundle of a family of Dirac operat

Stefan Schwarzer, Shlomo Havlin, Peter Ossadnik, H. Eugene Stanley

We develop the skeleton algorithm to define the number of main branches $N_b$ of diffusion-limited aggregation (DLA) clusters. The skeleton algorithm provides a systematic way to remove dangling side branches of the DLA cluster and has successfully been applied to study the ramification properties of percolation. We study the skeleton of comparatively large

T. P. Devereaux, R. T. Scalettar, G. T. Zimanyi, K. Moon

Localization of flux lines to splayed columnar pins is studied. A sine-Gordon type renormalization group study reveals the existence of a Splay glass phase and yields an analytic form for the transition temperature into the glass phase. As an independent test, the $I-V$ characteristics are determined via a Molecular Dynamics code. The glass transition temper

M. Langer, J. Schmalian, S. Grabowski, K. H. Bennemann

Using a new method for the solution of the FLEX-equations, which allows the determination of the self energy $Σ_{\bf k}(ω)$ of the $2D$ Hubbard model on the real frequency axis, we calculate the doping dependence of the quasi-particle excitations of High-T$_c$ superconductors. We obtain new results for the shadows of the Fermi surface, their dependence on th

S. Redner, P. L. Krapivsky

The survival probability of a particle diffusing in the two dimensional domain $x>0$ near a ``windy cliff&#39;&#39; at $x=0$ is investigated. The particle dies upon reaching the edge of the cliff. In addition to diffusion, the particle is influenced by a steady ``wind shear&#39;&#39; with velocity $\vec v(x,y)=v\,{\rm sign}(y)\,\hat x$, \ie, no average bias

K. Ziegler

Electrons on a square lattice with half a flux quantum per plaquette are considered. An effective description for the current loops is given by a two-dimensional Dirac theory with random mass. It is shown that the conductivity and the localization length can be calculated from a product of Dirac Green&#39;s functions with the {\it same} frequency. This impli

Wlodek Zadrozny

We present a model of NLP in which ontology and context are directly included in a grammar. The model is based on the concept of {\em construction}, consisting of a set of features of form, a set of semantic and pragmatic conditions describing its application context, and a description of its meaning. In this model ontology is embedded into the grammar; e.g.

Wlodek Zadrozny

We present an argument for {\em construction grammars} based on the minimum description length (MDL) principle (a formal version of the Ockham Razor). The argument consists in using linguistic and computational evidence in setting up a formal model, and then applying the MDL principle to prove its superiority with respect to alternative models. We show that

Roger Evans, Gerald Gazdar, David Weir

This paper shows how DATR, a widely used formal language for lexical knowledge representation, can be used to define an LTAG lexicon as an inheritance hierarchy with internal lexical rules. A bottom-up featural encoding is used for LTAG trees and this allows lexical rules to be implemented as covariation constraints within feature structures. Such an approac

Oleg Doroshenko, Sergei Kopeikin

An improved formula for the timing of binary pulsars that accounts for the relativistic deflection of light in the gravitational field of the pulsar&#39;s companion is presented, and the measurability of this effect together with its variance estimates are discussed. The deflection of the pulsar&#39;s beam trajectory in the gravitational field of its compani

Manolis Plionis

Comparing the observed peculiar velocities of the Local Group and of nearby Abell clusters of galaxies with those predicted using linear perturbation theory and the 3-D reconstruction algorithm of Branchini \& Plionis (1995) the value of $β$ can be estimated. I show that the anisotropy that causes the LG motion does not only extend to very large depths ($\si

Ichiro Shimada

We construct new examples of singular projective plane curves whose complements have finite and non-abelian fundamental groups, by generalizing the classical three cuspidal quartic curve discovered by Zariski.

Peter Kopietz

We use a bosonization approach to show that the momentum distribution $n_{\bf{k}}$ of normal Fermi systems with sufficiently singular interactions is analytic in the vicinity of the non-interacting Fermi surface. These include singular density-density interactions that diverge in $d$ dimensions stronger than $ | {\bf{q}} |^{- 2 (d -1)}$ for vanishing momentu

Bodil Branner, Núria Fagella

Given $p/q$ and $p&#39;/q$ both irreducible, we construct homeomorphisms between the $p/q$ and the $p&#39;/q$ limbs of the Mandelbrot set. This homeomorphisms are not compatible with the dynamics. Moreover, the filled Julia sets of corresponding parameter values are also homeomorphic. All the homeomorphisms above have counterparts on the combinatorial level

Hitoshi Murayama

There are supersymmetric gauge theories which do not possess any parameters nor flat directions, and hence cannot be studied anywhere in the field space using holomorphy (``non-calculable&#39;&#39;). Some of them are believed to break supersymmetry dynamically. We propose a simple technique to analyze these models. Introducing a vector-like field into the mo

Denny Fliegner, Peter Haberl, Michael G. Schmidt, Christian Schubert

Higher order coefficients of the inverse mass expansion of one--loop effective actions are obtained from a one--dimensional path integral representation. For the evaluation of the path integral with Wick contractions a suitable Green function has to be chosen. We consider the case of a massive scalar loop in the background of both a scalar potential and a (n

N. D. Hari Dass, B. E. Hanlon, T. Yukawa

Finite size effects for the Ising Model coupled to two dimensional random surfaces are studied by exploiting the exact results from the 2-matrix models. The fixed area partition function is numerically calculated with arbitrary precision by developing an efficient algorithm for recursively solving the quintic equations so encountered. An analytic method for

Amihay Hanany, Yaron Oz

We construct families of hyper-elliptic curves which describe the quantum moduli spaces of vacua of $N=2$ supersymmetric $SU(N_c)$ gauge theories coupled to $N_f$ flavors of quarks in the fundamental representation. The quantum moduli spaces for $N_f < N_c$ are determined completely by imposing $R$-symmetry, instanton corrections and the proper classical sin

J. H. Kuehn

It is demonstrated that the analyzing power of multi-meson final states in semileptonic $τ$ decays with respect to the $τ$ spin is equal and maximal for all decay modes.

J. P. Beaulieu, P. Grison, W. Tobin, J. D. Pritchard

We present CCD phase-binned light curves at 490 nm for 97 Cepheid variable stars in the bar of the LMC. The photometry was obtained as part of the French EROS project and has excellent phase coverage, permitting accurate decomposition into Fourier components. We identify as `sinusoidal&#39; or s-Cepheids those stars with periods less than 5.5 d and small sec

S. S. McGaugh, G. D. Bothun, J. M. Schombert

Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney (1976) suggested that the constancy of disk central surface brightness noticed by Freeman (1970) was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is

S. M. Bilenky, C. Giunti, C. W. Kim

Anticipating future long-baseline neutrino experiments to search for neutrino oscillations in various oscillation channels, we have analyzed the atmospheric neutrino data in the framework of a model with mixing of three massive neutrino fields that can accommodate the data of solar neutrino experiments. The oscillations of atmospheric and terrestrial neutrin

Gerald B. Cleaver

Consistent heterotic free fermionic string models are classified in terms of their number of spacetime supersymmetries, N. For each of the six distinct choices of gravitino sector, we determine what number of supersymmetries can survive additional GSO projections. We prove by exhaustive search that only three of the six can yield N = 1, in addition to the N

S. V. Klimenko, I. N. Nikitin, V. V. Talanov

A classification of stable singular points on world sheets of open relativistic strings is carried out.

I. N. Nikitin

A Hamiltonian formulation for the classical problem of electromagnetic interaction of two charged relativistic particles is found.

Alex Pomarol, Savas Dimopoulos

We analyze the soft supersymmetry breaking parameters obtained in grand unified theories after integrating out the heavy GUT-states. The superfield formalism greatly simplifies the calculations and allows us to derive the low-energy effective theory in the general case of non-universal and non-proportional soft terms by means of a few Feynman diagrams. We fi

Wei-Shu Hou, Gwo-Guang Wong

We study the magnetic field dependence of muonium--antimuonium conversion induced by neutral (pseudo)scalar bosons. Only the $SS$ operator contributes to the conversion of polarized muonium, but it gets quenched by a magnetic field of strength 0.1 Gauss or stronger. Conversion induced by $SS$ couplings for unpolarized muonium is independent of magnetic field

P. Ko

Productions and decays of spin-singlet $S,P-$wave charmonium states, $η_{c}^{&#39;}$ and $h_{c} (^{1}P_{1})$, in the $e^+ e^-$ annihilations are considered in the QCD multipole expansion with neglecting nonlocality in time coming from the color-octet intermediate states. Our approximation is opposite to the Kuang-Yan&#39;s model. The results are $B (ψ^{&#39;

Hyun S. Park

Synchronous Tree Adjoining Grammars can be used for Machine Translation. However, translating a free order language such as Korean to English is complicated. I present a mechanism to translate scrambled Korean sentences into English by combining the concepts of Multi-Component TAGs (MC-TAGs) and Synchronous TAGs (STAGs).

F. Malbet, C. Bertout

We present synthetic images of disks around T Tauri stars. We calculate visibility curves in order to study the possibility of directly detecting thermal emission from T Tauri disks. Total fluxes of T Tauri disks are compared to the sensitivity of VISA, the interferometric sub-array of the European Very Large Telescope. We conclude that thermal emission from

C. M. Hull, P. K. Townsend

Certain four-dimensional $N=4$ supersymmetric theories have special vacua in which massive charged vector supermultiplets become massless, resulting in an enhanced non-abelian gauge symmetry. We show here that any two $N=4$ theories having the same Bogomolnyi spectrum at corresponding points of their moduli spaces have the same enhanced symmetry groups. In p

Hoang Ngoc Long, Nguyen Ai Viet, Pham Xuan Yem

The inclusive decay rate into pions of the charmed $D_s$ meson is surprisingly larger than estimates expected from the $W$ annihilation, adopting commonly used values of current-algebra up and down quark masses. We then go beyond this tree diagram and consider possible QCD effects that might cause such a large rate. There are two; the first one is related to

Zarko Bizaca

We consider ribbon $R^4$&#39;s, that is, smooth open 4-manifolds, homeomorphic to $R^4$ and associated to $h$-cobordisms between closed 4-manifolds. We show that any generalized ribbon $R^4$ associated to a sequence of $h$-cobordisms between non-diffeomorphic 4-manifolds is exotic. Notion of a positive ribbon $R^4$ is defined and we show that a ribbon $R^4$

E. T. Akhmedov, M. N. Chernodub, M. I. Polikarpov, M. A. Zubkov

Starting from the Abelian Higgs field theory, we construct the theory of quantum Abrikosov--Nielsen--Olesen strings. It is shown that in four space -- time dimensions in the limit of infinitely thin strings, the conformal anomaly is absent, and the quantum theory exists. We also study an analogue of the Aharonov--Bohm effect: the corresponding topological in

Bertrand Berche, Ferenc Iglói

Supersymmetric quantum mechanics is well known to provide, together with the so-called shape invariance condition, an elegant method to solve the eigenvalue problem of some one-dimensional potentials by simple algebraic manipulations. In the present paper, this method is used in statistical physics. We consider the local critical behaviour of inhomogeneous I

Gerd Dethloff

We prove the following generalization of Severi&#39;s Theorem: Let $X$ be a fixed complex variety. Then there exist, up to birational equivalence, only finitely many complex varieties $Y$ of general type of dimension at most three which admit a dominant rational map $f$ from $X$ to Y$.

C. Bertoni, E. Carretti, F. Finelli, A. Messina

The possible cosmological effects of primordial fluctuation corrections to the evolution equation of matter obtained from the Wheeler--De Witt equation are explored. In particular, both the metric and a scalar matter field are expanded around their homogeneous values and the corrections induced on the scalar field fluctuation spectrum are perturbatively esti

Chang-Hwan Lee, Dong-Pil Min, Mannque Rho

S-wave $K^-p$ scattering into various channels near threshold are analyzed in heavy-baryon chiral perturbation theory with $Λ(1405)$ introduced as an independent field. This is the approach that predicted the critical density $2<=ρ_c/ρ_0 <=3$ for negatively charged kaon condensation. We show that chiral perturbation expansion treating the $Λ(1405)$ as elemen

M. Reyes, H. C. Rosu, O. Obregón

We show that asymmetric time-continuous discrete random walks can display bistability for equal values of Jauslin&#39;s shifting parameters. The bistability becomes more pronounced at increased asymmetry parameter

Andrzej J. ~Maciejewski, Jean-Marie Strelcyn

It is proved that the Halphen system of ordinary differential equations has no non-trivial rational first integrals.

Hyeong-Chan Kim, Min-Ho Lee, Jeong-Young Ji, Jae Kwan Kim

In the Heisenberg picture, the generalized invariant and exact quantum motions are found for a time-dependent forced harmonic oscillator. We find the eigenstate and the coherent state of the invariant and show that the dispersions of these quantum states do not depend on the external force. Our formalism is applied to several interesting cases.

Carlo Presilla, Ubaldo Tambini

We propose a numerical method for evaluating eigenvalues and eigenfunctions of Schrödinger operators with general confining potentials. The method is selective in the sense that only the eigenvalue closest to a chosen input energy is found through an absolutely-stable relaxation algorithm which has rate of convergence infinite. In the case of bistable potent

C. Schulte, R. Twarock, A. Bohm

Quantum mechanics in the Rigged Hilbert Space formulation describes quasistationary phenomena mathematically rigorously in terms of Gamow vectors. We show that these vectors exhibit microphysical irreversibility, related to an intrinsic quantum mechanical arrow of time, which states that preparation of a state has to precede the registration of an observable

St. Hollinger, M. Luecke

Linear and nonlinear properties of convection in binary fluid layers heated from below are investigated, in particular for gas parameters. A Galerkin approximation for realistic boundary conditions that describes stationary and oscillatory convection in the form of straight parallel rolls is used to determine the influence of the Dufour effect on the bifurca

Peter B. Siegel, Bijan Saghai

The effects of the initial state interactions on the $K^--p$ radiative capture branching ratios are examined and found to be quite sizable. A general coupled-channel formalism for both strong and electromagnetic channels using a particle basis is presented, and applied to all the low energy $K^--p$ data with the exception of the {\it 1s} atomic level shift.

Jens Konopka, Horst Stoecker, Walter Greiner

Spectra of various particle species have been calculated with the Quantum Molecular Dynamics (QMD) model for very central collisions of Au+Au. They are compatible with the idea of a fully stopped thermal source which exhibits a transversal expansion besides the thermal distribution of an ideal gas. However, the microscopic analyses of the local flow velociti

Tae-Sun Park, Dong-Pil Min, Mannque Rho

Exchange vector currents are calculated up to one-loop order (corresponding to next-to-next-to-leading order) in chiral perturbation theory. As an illustration of the power of the approach, we apply the formalism to the classic nuclear process $n+p\rightarrow d +γ$ at thermal energy. The exchange current correction comes out to be $(4.5 \pm 0.3)$ \% in ampli

Bao-An Li, Che Ming Ko

We present the detail of a newly developed relativistic transport model (ART 1.0) for high energy heavy-ion collisions. Using this model, we first study the general collision dynamics between heavy ions at the AGS energies. We then show that in central collisions there exists a large volume of sufficiently long-lived superdense hadronic matter whose local ba

Bao-An Li, Sherry J. Yennello

We study the equilibration of isospin degree of freedom in intermediate energy heavy-ion collisions using an isospin-dependent BUU model. It is found that there exists a transition from the isospin equilibration at low energies to non-equilibration at high energies as the beam energy varies across the Fermi energy in central, asymmetric heavy-ion collisions.

R. E. Cohen

Linearized augmented plane wave (LAPW) calculations are performed for periodic (001) and (111) slabs of BaTiO$_3$ to understand the effects of surfaces on ferroelectric BaTiO$_3$. The (111) slab is found to be much less stable than the (001) slab. The average surface energies are respectively 3700 erg/cm$^2$ and 1600 erg/cm$^2$. The depolarization field is s

Oscar Pla

Motivated by recent experiments by Yuse and Sano (Nature, 362, 329 (1993)), we propose a discrete model of linear springs for studying fracture in thin and elastically isotropic brittle films. The method enables us to draw a map of the stresses in the material. Cracks generated by the model, imposing a moving thermal gradient in the material, can branch or w

Jorge Alfaro, Ricardo Medina, Luis F. Urrutia

Starting from the generalization of the Itzykson-Zuber integral for $U(m|n)$ we determine the orthogonality relations for this supergroup.

David A. Lowe

It has been argued that the consistency of quantum theory with black hole physics requires nonlocality not present in ordinary effective field theory. We examine the extent to which such nonlocal effects show up in the perturbative S-matrix of string theory.

Silvio J. Rabello, Arvind N. Vaidya

The path integral representation for a system of N non-relativistic particles on the plane, interacting through a Chern-Simons gauge field, is obtained from the operator formalism. An effective interaction between the particles appears, generating the usual Aharonov-Bohm phases. The spin-statistics relation is also considered.

C. Quesne

The exchange operator formalism previously introduced for the Calogero problem is extended to the three-body Calogero-Marchioro-Wolfes one. In the absence of oscillator potential, the Hamiltonian of the latter is interpreted as a free particle Hamiltonian, expressed in terms of generalized momenta. In the presence of oscillator potential, it is regarded as a

Stephan Elser, Hans-Christian Pauli, Alex C. Kalloniatis

We describe the programming method for generating the spectrum of bound states for relativistic quantum field theories using the nonperturbative Hamiltonian approach of Discretized Light-Cone Quantization. The method is intended for eventual application to quantum chromodynamics in 3+1 dimensions. Here the fundamental principles are illustrated concretely by

Karol Kołodziej, Arnd Leike, Reinhold Rückl

We investigate hadroproduction of $B_c$ mesons from initial gluons using QCD perturbation theory and nonrelativistic bound state approximations. Our results obtained by two completely independent calculations are confronted with existing results which contradict each other. Moreover, we examine the approximation based on heavy quark fragmentation and determi

M. Drees, R. M. Godbole

We calculate the contribution to inclusive high tranverse momentum ($p_T$) charm production at HERA from the excitation of charm in the photon. At large values of \pt\ the results of such a calculation, in the structure function language, will be more reliable as it sums the large logs, $\log(p_T^2/m_c^2)$, as opposed to calculating the contribution of the $

T. Barklow, S. Dawson, H. Haber, J. Siegrist

This is a report of the Electroweak Symmetry Breaking and Beyond the Standard Model Working Group which was prepared for the Division of Particles and Fields Committee for Long Term Planning. We study the phenomenology of electroweak symmetry breaking and attempt to quantify the &#34;physics reach&#34; of present and future colliders. Our investigations enco

P. Binetruy, E. Dudas

We analyze the general structure of the fermion mass matrices in effective superstrings. They are generically given at low energy by non-trivial functions of the gauge singlet moduli fields. Interesting structures appear in particular if they are homogeneous functions of zero degree in the moduli. In this case we find Yukawa matrices very similar to the ones

Kimball A. Milton

Julian Schwinger began the construction of Source Theory in 1966 in response to the then apparent failure of quantum field theory to describe strong interactions, the physical remoteness of renormalization, and the utility of effective actions in describing chiral dynamics. I will argue that the source theory development was not really so abrupt a break with

B. E. Hanlon, G. C. Joshi

We extend the BRS and anti-BRS symmetry to the two point space of Connes&#39; non-commutative model building scheme. The constraint relations are derived and the quantum Lagrangian constructed. We find that the quantum Lagrangian can be written as a functional of the curvature for symmetric gauges with the BRS, anti-BRS auxiliary field finding a geometrical

Zygmunt Lalak, Stefan Pokorski, Julius Wess

Effective Lagrangian describing gravitational source spin-particle spin interactions is given. Cosmological and astrophysical consequences of such interaction are examined. Although stronger than expected, the spin-spin interactions do not change any cosmological effect observed so far. They are important for background primordial neutrinos.

Vikram Soni

We show that the quark (not nucleon) based chiral linear $σ$ model which receives strong support as a mean field theory for the strong interactions can actually be made asymptotically free by coupling to gluons. It has the further bonus of providing confinement.Alternatively, this theory is QCD that is chirally extended by the addition of a $(σ,π)$ chiral mu

Martin Luescher, Peter Weisz

The perturbation expansion of the MSbar coupling in the SU(N) gauge theory in powers of the bare lattice coupling is extended to two-loop order. A discussion of our results has already been published elsewhere. We here describe the calculation in some detail. It relies on the background field technique and a recently introduced coordinate space method to eva

S. Abachi

The $WWγ$ gauge boson couplings were measured using $p\bar{p}\to \ellνγ+X$ ($\ell=e,μ$) events at $\sqrt{s}=1.8$ TeV observed with the {DØ} detector at the Fermilab Tevatron Collider. The signal, obtained from the data corresponding to an integrated luminosity of $13.8 {\rm pb}^{-1}$, agrees well with the Standard Model prediction. A fit to the photon transv

C. A. Stafford, S. Das Sarma

The conductance in an extended multiband Hubbard model describing linear arrays of up to ten quantum dots is calculated via a Lanczos technique. A pronounced suppression of certain resonant conductance peaks in an applied magnetic field due to a density-dependent spin-polarization transition is predicted to be a clear signature of a coherent ``molecular&#39;

E. TOSATTI

I present an informal discussion of various cases where two-dimensional surface metal-insulator structural and charge-density-wave instabilities driven by partly filled surface states have been advocated. These include reconstructions of clean semiconductor surfaces and of W(100) and Mo(100), as well as anomalies on the hydrogen-covered surfaces H/W(110) and