May 1994 arXiv papers — page 8

C. Duval, P. A. Horvathy, L. Palla

The construction and the symmetries of Chern-Simons vortices in harmonic and uniform magnetic force backgrounds found by Ezawa, Hotta and Iwazaki, and by Jackiw and Pi are generalized using the non-relativistic Kaluza-Klein-type framework presented in our previous paper. All Schrodinger-symmetric backgrounds are determined.

Gustav W. Delius, Mark D. Gould, Yao-Zhong Zhang

We describe the construction of trigonometric R-matrices corresponding to the (multiplicity-free) tensor product of any two irreducible representations of a quantum algebra $U_q(\G)$. Our method is a generalization of the tensor product graph method to the case of two different representations. It yields the decomposition of the R-matrix into projection oper

W. E. Ormand, P. M. Pizzochero, P. F. Bortignon, R. A. Broglia

Shell-model calculations of solar neutrino absorption cross sections for $^{40}$Ar, the proposed component of the ICARUS detector, are presented. It is found that low-lying Gamow-Teller transitions lead to a significant enhancement of the absorption rate over that expected from the Fermi transition between the isobaric analog states, leading to an overall ab

O. Castaños, R. López-Peña, V. I. Man'ko

The infinite number of time-dependent linear in field and conjugated momenta invariants is derived for the scalar field using the Noether's theorem procedure.

A. Fring, P. R. Johnson, M. A. C. Kneipp, D. I. Olive

In a space-time of two dimensions the overall effect of the collision of two solitons is a time delay (or advance) of their final trajectories relative to their initial trajectories. For the solitons of affine Toda field theories, the space-time displacement of the trajectories is proportional to the logarithm of a number $X$ depending only on the species of

Victor M. Villalba

The Dirac equation in spherically symmetric fields is separated in two different tetrad frames. One is the standard cartesian (fixed) frame and the second one is the diagonal (rotating) frame. After separating variables in the Dirac equation in spherical coordinates, and solving the corresponding eingenvalues equations associated with the angular operators,

P. Geiger, E. S. Swanson

Two competing models for strong hadronic decays, the $^3P_0$ and $^3S_1$ models, are currently in use. Attempts to rule out one or the other have been hindered by a poor understanding of final state interactions and by ambiguities in the treatment of relativistic effects. In this article we study meson decays in both models, focussing on certain amplitude ra

H. G. Dosch, Erasmo Ferreira, A. Krämer

Total cross-sections and logarithmic slopes of the elastic scattering cross-sections for different hadronic processes are calculated in the framework of the model of the stochastic vacuum. The relevant parameters of this model, a correlation length and the gluon condensate, are determined from scattering data, and found to be in very good agreement with valu

R. Vogt, S. J. Brodsky

Recent experiments at Fermilab and CERN have observed a strong asymmetry between the hadroproduction cross sections of leading $D$ mesons, containing projectile valence quarks, and nonleading charmed mesons, without projectile valence quarks. The observed correlations of the $π^{\pm} N \to D^\pm X$ cross section with the projectile charge violates the usual

Gautam Bhattacharyya, Amitava Raychaudhuri

We investigate the impact of a light gluino, which might have escaped detection at colliders, on inclusive radiative $B$-decays mediated through penguin-like diagrams. We find that the viability of the scenario depends largely on the magnitude of the flavour-violating $c$-parameter. Some previously allowed regions of parameter space are now ruled out.

K. Farakos, K. Kajantie, K. Rummukainen, M. Shaposhnikov

We study the finite temperature electroweak transition with non-perturbative lattice Monte Carlo simulations. We find that it is of first order, at least for Higgs masses up to 80 GeV. The critical temperature of the phase transition is found to be smaller than that determined by a 2-loop renormalization group improved effective potential. The jump of the or

A. Timmermann, M. Pluemer, L. V. Razumov, R. M. Weiner

The Bose-Einstein correlations of photons emitted {}from a longitudinally expanding system of excited matter produced in ultrarelativistic heavy ion collision are studied. Two effects found in recent calculations -- that the correlation function in longitudinal direction exhibits oscillations, and that it takes values below unity -- are demonstrated to be nu

J. Hrivnac, R. Lednicky, M. Smizanska

The possibility of beauty baryon polarization measurement by cascade decay angular distribution analysis in the channel Lambda0 J/psi --> p pi- l+ l- is demonstrated. The error analysis shows that in the proposed LHC experiment ATLAS at the luminosity $10^{4} pb^{-1}$ the polarization can be measured with the statistical precision better than $δ=0.010$ for L

C. Greub, D. Wyler, S. Brodsky, C. Munger

We consider the transitions between electromagnetic bound states, such as the exclusive weak decay of a muonic atom into an electronic atom: $(μ^- Z) \to (e^- Z) {\bar ν_e }ν_μ. $ We show that relativistic effects in the atomic wavefunctions are crucial for determining the rate. In the case of heavy atoms, the exclusive channel branching ratios exceed $10^{-

Soffer, O. V. Teryaev

The contribution of the $G_2$ structure function to polarized deep inelastic scattering is slightly redefined in order to avoid kinematical zeros. Its strong $Q^2$-dependence implied by the Burkhardt-Cottingham (BC) sum rule naturally explains the sign change of the generalized Gerasimov-Drell-Hearn (GDH) sum rule. The status of the BC sum rule and implicati

Jaewan Kim, Pierre Sikivie

How does the amplitude of a wiggle on a string change when the string is stretched? We answer this question for both longitudinal and transverse wiggles and for arbitrary equation of state, {\it i.e.}, for arbitrary relation between the tension $τ$ and the energy per unit length $ε$ of the string. This completes our derivation of the renormalization of strin

Hai-Yang Cheng

Armed with the information on the form factor $\fdpi(0)$ inferred from recent CLEO measurements of SU(3)-breaking effects in charmed meson decays, we have studied the form factor $\fbpi$. In the heavy quark limit, $\fbpi(q^2)$ is related to $\fdpi(q^2)$ in the kinematic region close to zero recoil. Assuming pole dominance for its $q^2$ dependence, $\fbpi(0)$

Martin Bäker

We show numerically that the lowest eigenmodes of the 2-dimensional Laplace-operator with SU(2) gauge couplings are strongly localized. A connection is drawn to the Anderson-Localization problem. A new Multigrid algorithm, capable to deal with these modes, shows no critical slowing down for this problem.

U. Bleyer, M. Rainer, A. Zhuk

Consider multidim. universes M= R x M_1 x ... x M_n with D = 1+ d_1 .. + d_n, where M_i of dimension d_i are of have constant curvature and compact for i>1. For Lagrangian models L(R,phi) on M which depend only on Ricci curvature R and a scalar field phi, there exists an explicit description of conformal equivalence, with the minimal coupling model and the c

M. Moreno, R. M. Méndez-Moreno, S. Orozco, M. A. Ortíz

A new pairing theory for many-fermion systems is obtained via the Dirac supersymmetry framework recently introduced to describe Dirac particles in external potentials. It is shown that the standard Bogoliubov-Valatin canonical transformation treatment of the quasi-particle BCS singlet pairing mechanism naturally falls within this framework. Straightforward g

Stephen D. Murray, John I. Castor, Richard I. Klein, Christopher F. McKee

We present the results of self-consistent models of Compton-heated accretion disk coronae. The models are calculated using a new method for computing monochromatic radiative transfer in two-dimensions. The method splits the radiation into direct and scattered components. The direct radiation is computed by calculating the optical depth along rays, while tran

Takamitsu Miyaji, Ofer Lahav, Keith Jahoda, Elihu Boldt

We have cross-correlated the galaxies from the IRAS 2 Jy redshift survey sample and the 0.7 Jy projected sample with the all-sky cosmic X-ray background (CXB) map obtained from the HEAO-1 A2 experiment. We have developed a formulation to model the cross-correlation between CXB surface brightness and galaxy counts. This includes the effects of source clusteri

Daniel J. Eisenstein, Abraham Loeb

We present an analytical model for the non-spherical collapse of overdense regions out of a Gaussian random field of initial cosmological perturbations. The collapsing region is treated as an ellipsoid of constant density, acted upon by the quadrupole tidal shear from the surrounding matter. The dynamics of the ellipsoid is set by the ellipsoid self-gravity

A. Beauville

The Verlinde formula computes the dimension of certain vector spaces ("conformal blocks") associated to a Rational Conformal Field Theory. In this paper we show how this can be made rigorous for one particular such theory, the WZW model. Thanks to the results of [B-L], [F] and [T-U-Y], this gives the dimension of the space of global sections of the d

M. Bauer, D. Z. Freedman, P. E. Haagensen

A unitary transformation $\Ps [E]=\exp (iØ[E]/g) F[E]$ is used to simplify the Gauss law constraint of non-abelian gauge theories in the electric field representation. This leads to an unexpected geometrization because $ø^a_i\equiv -\dØ[E]/\d E^{ai}$ transforms as a (composite) connection. The geometric information in $ø^a_i$ is transferred to a gauge invari

D. J. Dean, S. E. Koonin, K. Langanke, P. B. Radha

We study the thermal properties of Fe-54 with the Brown-Richter interaction in the complete 1p0f model space. Monte Carlo calculations show a peak in the heat capacity and rapid increases in both the moment of inertia and M1 strength near a temperature of 1.1 MeV that are associated with the vanishing of proton-proton and neutron-neutron monopole pair correl

Fred Cooper, Avinash Khare, Uday Sukhatme

In the past ten years, the ideas of supersymmetry have been profitably applied to many nonrelativistic quantum mechanical problems. In particular, there is now a much deeper understanding of why certain potentials are analytically solvable and an array of powerful new approximation methods for handling potentials which are not exactly solvable. In this repor

Detlef Lohse, Axel Mueller-Groeling

We (analytically) calculate the energy spectrum corresponding to various experimental and numerical turbulence data analyzed by Benzi et al.. We find two bottleneck phenomena: While the local scaling exponent $ζ_r(r)$ of the structure function decreases monotonically, the local scaling exponent $ζ_p(p)$ of the corresponding spectrum has a minimum of $ζ_p(p_{

I. Antoniadis, E. Gava, K. S. Narain, T. R. Taylor

In four-dimensional compactifications of the heterotic superstring theory the Kähler potential has a form which generically induces a superpotential mass term for Higgs particles once supersymmetry is broken at low energies. This ``$μ$-term'' is analyzed in a model-independent way at the tree level and in the one-loop approximation, and explicit expr

H. J. de Vega, A. González--Ruiz

The $SU_{q}(n)$ generators are obtained as large spectral parameter limit of the Yang-Baxter operators in the integrable $SU_{q}(n)$ invariant vertex model. The commutation relations, including Serre relations, are obtained as limits of the Yang-Baxter equations. The recently found eigenvectors of the $SU_{q}(n)$ invariant spin chains are shown to be Highest

Thomas M. Gould, I. Z Rothstein

We show that single photon searches at LEP constrain the tau neutrino magnetic moment to be less than ${\cal O}(10^{-6})~μ_B$. This bound is competitive with low energy ($s\simeq (30~GeV)^2$) single photon searches.

Jianming Zhang, Subal Das Gupta, Charles Gale

We use the Boltzmann-Uehling-Uhlenbeck model to simulate the dynamical evolution of heavy ion collisions and to compare the effects of two parametrizations of the momentum--dependent nuclear mean field that have identical properties in cold nuclear matter. We compare with recent data on nuclear flow, as characterized by transverse momentum distributions and

G. Colo`, N. Van Giai, P. F. Bortignon, R. A. Broglia

The properties of charge-exchange excitations of ${}^ {208}$Pb with $ΔL = 0$, i.e., the isobaric analog and Gamow-Teller resonances, are studied within a self-consistent model making use of an effective force of the Skyrme type. The well-known isobaric analog case is used to assess the reliability of the model. The calculated properties of the Gamow-Teller r

D. Bailin, A. Love, W. A. Sabra, S. Thomas

The values of the $T$ and $U$ moduli are studied for those ${\bf Z}_N $ Coxeter orbifolds with the property that some of the twisted sectors have fixed planes for which the six-torus ${\bf T}^6 $ can not be decomposed into a direct sum ${\bf T}^2\bigoplus {\bf T}^4 $ with the fixed plane lying in ${\bf T}^2 $. Such moduli in general transform under a subgrou

D. Caenepeel, R. MacKenzie

Some general features of the scattering of boson-based anyons with an added non-statistical interaction are discussed. Periodicity requirements of the phase shifts are derived, and used to illustrate the danger inherent in separating these phase shifts into the well-known pure Aharanov-Bohm phase shifts, and an additional set which arise due to the interacti

A. L. Larsen, N. Sanchez

We study the string propagation in the 2+1 black hole anti de Sitter background (2+1 BH-ADS). We find the first and second order fluctuations around the string center of mass and obtain the expression for the string mass. The string motion is stable, all fluctuations oscillate with real frequencies and are bounded, even at $r=0.$ We compare with the string m

Steffen Mallwitz

We construct free field representations of the $SW$-algebras SW(3/2,2) and SW(3/2,3/2,2) by using the corresponding Toda-Field-Theories. In constructing the series of minimal models using covariant vertex operators, we find a necessary restriction on the Cartan matrix of the Super-Lie-Algebra, also for the general case. Within this framework, this restrictio

Bin Chen, Takesi Saito, Ke Wu

Using the differential calculus on discrete group, we study the general relativity in the space-time which is the product of a four dimensional manifold by a two-point space. We generalize the usual concept of frame and connection in our space-time, and from the generalized torsion free condition we obtain an action of a scalar field coupled to Einstein grav

D. K. Park

Delta-function potentials in two- and three-dimensional quantum mechanics are analyzed by the incorporation of the self-adjoint extension method to the path integral formalism. The energy-dependent Green functions for free particle plus delta-function potential systems are explicitly calculated. Also the energy-dependent Green function for the spin-1/2 Aharo

Yu-kui Zhou, Paul A. Pearce

Fusion hierarchies of \ade face models are constructed. The fused critical $D$, $E$ and elliptic $D$ models yield new solutions of the Yang-Baxter equations with bond variables on the edges of faces in addition to the spin variables on the corners. It is shown directly that the row transfer matrices of the fused models satisfy special functional equations. I

J. Kripfganz, A. Laser, M. G. Schmidt

We discuss the critical bubbles of the electroweak phase transition using an effective high-temperature 3-dimensional action for the Higgs field $φ$. The separate integration of gauge and Goldstone boson degrees of freedom is conveniently described in the 't Hooft-Feynman covariant background gauge. The effective dimensionless gauge coupling $g_3(T)^2$ i

V. Barger, R. J. N. Phillips

The first evidence for the top quark at the Tevatron may indicate a cross section higher than the QCD expectation. We consider the possibility that isosinglet heavy quarks may be contributing to the signal and discuss ways of testing this possibility. For example, a charge $\case2/3$ singlet quark, approximately degenerate and mixing with the top quark, woul

Alon E. Faraggi, Edi Halyo

We examine the problem of supersymmetry breaking in realistic superstring standard--like models which are constructed in the free fermionic formulation. We impose a supersymmetric vacuum at the Planck scale by requiring vanishing F and D constraints at the cubic level of the superpotential. We then study possible scenarios for supersymmetry breaking by exami

L. M. A. Bettencourt, R. J. Rivers

We derive analytic expressions for the interaction energy between two general $U(1)$ cosmic strings as the function of their relative orientation and the ratio of the coupling constants in the model. The results are relevant to the statistic description of strings away from critical coupling and shed some light on the mechanisms involved in string formation

L. M. A. Bettencourt, T. W. B. Kibble

It is shown that for small relative angle and kinetic energy two type I $U(1)$ strings can form bound states upon collision instead of the more familiar intercommuting configuration. The velocity below which this may happen is estimated as function of the ratio of the coupling constants in the theory, crossing angle and initial kinetic energy.

X. Martin, P. Peter

The dynamical stability of cosmic rings, or vortons, is investigated for the particular equation of state given by the Witten bosonic model. It is found that there exists a finite range of the state parameter for which the vorton states are actually stable against dynamical perturbations. Inclusion of the electromagnetic self action into the equation of stat

Xiao-Xi Chen, Wen-Gan Ma, Yao-Yang Liu, La-Zhen Sun

The electroweak corrections at one-loop level to the process $H\rightarrow t{\bar t}$ are calculated, especially the fresh top mass value announced recently by CDF is concerned. For $M_H < 1. TeV$ where a perturbative calculation is valid, the corrections themselves would gain a few to 20 percent increment in the decay width as the Higgs mass $M_H$ is increa

Stanley J. Brodsky, Hung Jung Lu

We use the BLM method to show that perturbatively-calculable observables in QCD can be related to each other without renormalization scale or scheme ambiguity. We define and study the commensurate scale relations. We show that the commensurate scales satisfy the renormalization group transitivity rule which ensures that predictions in PQCD are independent of

L. Randall, N. Rius

We present a detailed analysis of the use of heavy quark fragmentation into heavy hadrons for testing the heavy quark effective theory through comparison of the measured fragmentation parameters of the $c$ and $b$ quarks. Our analysis is entirely model independent. We interpret the known perturbative evolution in a way useful for exploiting heavy quark symme

Carl H. Brans

The essential role played by differentiable structures in physics is reviewed in light of recent mathematical discoveries that topologically trivial space-time models, especially the simplest one, ${\bf R^4}$, possess a rich multiplicity of such structures, no two of which are diffeomorphic to each other and thus to the standard one. This means that physics

Henk van Elst, Peter Dunsby, Reza Tavakol

Inflationary models and their claim to solve many of the outstanding problems in cosmology have been the subject of a great deal of debate over the last few years. A major sticking point has been the lack of both good observational and theoretical arguments to single out one particular model out of the many that solve these problems. Here we examine the degr

Peter Dunsby, Marco Bruni

Given that observations seem to favour a \index{density parameter} $Ω_0<1$, corresponding to an open universe, we consider gauge\hs invariant perturbations of non\hs flat Robertson\hs Walker universes filled with a general imperfect fluid which can also be taken to represent a scalar field. Our aim is to set up the equations that govern the evolution of the

R. F. Angulo, E. Medina

The self averaging properties of conductance $g$ are explored in random resistor networks with a broad distribution of bond strengths $P(g)\simg^{μ-1}$. Distributions of equivalent conductances are estimated numerically on hierarchical lattices as a function of size $L$ and distribution tail parameter $μ$. For networks above the percolation threshold, conver

M. L. Plumer, A. Mailhot, A. Caillé

Extensive histogram Monte-Carlo simulations of the XY antiferromagnet on a stacked triangular lattice reveal exponent estimates which strongly favor a scenario of mean-field tricritical behavior for the spin-order transition. The corresponding chiral-order transition occurs at the same temperature but appears to be decoupled from the spin-order. These result

S. Clar, B. Drossel, F. Schwabl

We discuss the properties of a self--organized critical forest--fire model which has been introduced recently. We derive scaling laws and define critical exponents. The values of these critical exponents are determined by computer simulations in 1 to 8 dimensions. The simulations suggest a critical dimension $d_c=6$ above which the critical exponents assume

S. Franz, G. Parisi, M. A. Virasoro

In this paper we try to estimate the lower critical dimension for replica symmetry breaking in spin glasses through the calculation of the additional free-energy required to create a domain wall between two different phases. This mechanism alone would say that replica symmetry would be restored at the lower critical dimension $D_c =2.5$.

Iwan Jensen

Recently, Takayasu and Tretyakov [Phys. Rev. Lett. {\bf 68}, 3060 (1992)], studied branching annihilating random walks (BAW) with $n=1$-5 offspring. These models exhibit a continuous phase transition to an absorbing state. For odd $n$ the models belong to the universality class of directed percolation. For even $n$ the particle number is conserved modulo 2 a

Paolo Catelan, Robert J. Scherrer

We examine the multi--point velocity field for non--Gaussian models as a probe of non--Gaussian behavior. The two--point velocity correlation is not a useful indicator of a non--Gaussian density field, since it depends only on the power spectrum, even for non--Gaussian models. However, we show that the distribution of velocity differences $\bfv_1 - \bfv_2$,

F. Butler, H. Chen, J. Sexton, A. Vaccarino

We evaluate pseudoscalar, vector, spin 1/2 and spin 3/2 baryon masses predicted by lattice QCD with Wilson quarks in the valence (quenched) approximation for a range of different values of lattice spacing, lattice volume and quark mass. Extrapolating these results to physical quark mass, then to zero lattice spacing and infinite volume we obtain values for e

S. Pakuliak, A. Perelomov

A simple property of the integrals over the hyperelliptic surfaces of arbitrary genus is observed. Namely, the derivatives of these integrals with respect to the branching points are given by the linear combination of the same integrals. We check that this property is responsible for the solution to the level zero Knizhnik-Zamolodchikov equation given in ter

C. Arzt, M. B. Einhorn, J. Wudka

Effective Lagrangians can be used to parametrize the effects of physics beyond the standard model. Assuming the complete theory is a gauge theory, we determine which effective operators may be generated at tree level, and which are only generated at loop level. The latter are be suppressed by factors of $1/ 16\pi^2$ and will therefore be quite difficult to d

O. A. Soloviev

We discuss a new type of unitary perturbations around conformal theories inspired by the $σ$-model perturbation of the nonunitary WZNW model. We show that the nonunitary level $k$ WZNW model perturbed by its sigma model term goes to the unitary level $-k$ WZNW model. When plugged into the gauged WZNW model the given perturbation results in the perturbed gaug

B. A. C. C. Bassett, P. K. S. Dunsby, G. F. R. Ellis

In this paper we examine the change in the estimated spatial power spectra at decoupling due to the effects of our clumpy universe which modify observational distances. We find that scales at decoupling can be significantly underestmated in our approximation of neglecting the shear of the ray bundle. We compare our results with other work on lensing and spec

Richard Sproat, Chilin Shih, William Gale, Nancy Chang

We present a stochastic finite-state model for segmenting Chinese text into dictionary entries and productively derived words, and providing pronunciations for these words; the method incorporates a class-based model in its treatment of personal names. We also evaluate the system&#39;s performance, taking into account the fact that people often do not agree

J. Pantaleone

(The discussion is expanded, and a mistake in the crossing probability is corrected.)

Derek B. Leinweber

Results for the first test of the ``crude&#39;&#39; QCD continuum model, commonly used in QCD Sum Rule analyses, are presented for baryon correlation functions. The QCD continuum model is found to effectively account for excited state contributions to the short-time regime of two-point correlation functions and allows the isolation of ground state properties

David M. Magerman

Traditional natural language parsers are based on rewrite rule systems developed in an arduous, time-consuming manner by grammarians. A majority of the grammarian&#39;s efforts are devoted to the disambiguation process, first hypothesizing rules which dictate constituent categories and relationships among words in ambiguous sentences, and then seeking except

J. Navarro-Salas, M. Navarro, C. F. Talavera

We determine the canonical structure of two-dimensional black-hole solutions arising in $2D$ dilaton gravity. By choosing the Cauchy surface appropriately we find that the canonically conjugate variable to the black hole mass is given by the difference of local (Schwarzschild) time translations at right and left spatial infinities. This can be regarded as a

S. Narison

Using the QCD {\it hybrid} (moments-Laplace) sum rule, we show $semi$-$analytically$ that, in the limit $M_b \rar \infty$, the $q^2$ and $M_b$ behaviours of the heavy-to-light exclusive ($\bar B\rar ρ~(π)$ semileptonic as well as the $ B\rar ργ$ rare) decay--form factors are $universally$ dominated by the contribution of the soft light-quark condensate rathe

A. Koubek

The form-factor bootstrap approach is applied to the perturbed minimal models $M_{2,2n+3}$ in the direction of the primary field $ϕ_{1,3}$. These theories are integrable and contain $n$ massive scalar particles, whose $S$--matrix is purely elastic. The form-factor equations do not refer to a specific operator. We use this fact to classify the operator conten

L. Frankfurt, E. Piasetsky, M. Sargsyan, M. Strikman

We show that the strong dependence of the amplitude for $NN$ hard scattering on the collision energy can be used to magnify the effects of short range nucleon correlations in quasielastic $pd$ scattering. Under specific kinematical conditions the effect of initial and final state interactions can be accounted for by rescaling the cross section calculated wit

S. J. Gates, O. A. Soloviev

We present the theory describing supersymmetrical vortices in the curved superspace of the (1,0) supergravity. The action is defined as a (1,0) locally supersymmetric $SU(2)/U(1)$ coset perturbed by the cosmological constant-like term. The perturbation is such that it preserves the integrability of the coset model. Because of supersymmetry the perturbed theo

Koichi HAYASHI, Toshiharu SAMURA

The scattering process of two particles at Planck energies or beyond is calculated using the gravitational shock wave metric for a massive black hole. Then, the scattering between a heavy mass particle and a small mass one is deal with. The cross section contains an extra new term of $σ\propto G^3$ as the correction term of the leading term derived by &#39;t

S. Davidson, K. Kainulainen, K. A. Olive

We consider the evolution of baryon number $B$ in the early universe under the influence of rapid sphaleron interactions and show that $B$ will remain nonzero at all times even in the case of $B-L = 0$. This result arises due to thermal Yukawa interactions that cause nonidentical dispersion relations (thermal masses) for different lepton families. We point o

Apoorva Patel

Isgur-Wise functions parametrise the leading behaviour of weak decay form factors of mesons and baryons containing a single heavy quark. The form factors for the quark mass operator are calculated in strong coupling lattice QCD, and Isgur-Wise functions extracted from them. Based on renormalisation group invariance of the operators involved, it is argued tha

Debajyoti Choudhury, Frank Cuypers

The effect of anomalous gauge couplings on polarized $e^- e^-$ scattering cross sections is examined. It turns out that different combinations of beam polarizations provide constraints that are complementary to each other and to those obtained from other experiments, such as $e^+ e^-$, $e^- γ$ and $γγ$ collisions.

C. N. Lovett-Turner

Progress has been made on the calculation of \(R_{3}\), the three-jet rate in \(e^{+}e^{-}\) annihilation, in the \(k_\bot \) (Durham) scheme. Using the coherent branching formalism \cite{b,c,d}, an explicit expression for \(R_{3}\) is calculated. In this, leading and next-to-leading large logarithms (LL and NLL) are resummed to all orders in QCD perturbatio

P V Landshoff

Nonperturbative pomeron exchange at high energy includes minijet production. At moderate $Q^2$ it is responsible for the small-$x$ behaviour of $νW_2$. Hence minijet production should be a feature of deep inelastic scattering at small $x$.

O. A. Borisenko, J. Bohàčik, V. V. Skalozub

A survey devoted to $A_0$-condensate in gauge theories at high temperature is presented. Both the theoretical foundations of the spontaneously generated condensate and known methods of its calculation are discussed. As most important consequence the SU(N) global symmetry breakdown is investigated in details. Influence of $A_0$ on matter fields is studied in

M. Shifman, N. G. Uraltsev, A. Vainshtein

We derive a model-independent upper bound for the axial-vector form factor of the $B\ra D^*$ transition at zero recoil, $F_{B\ra D^*}$. The form factor turns out to be noticeably less than unity. The deviation of $F_{B\ra D^*}$ from unity is larger than previously anticipated. Using our estimate we extract $|V_{cb}|$ from the measured exclusive rate of $B\ra

Maarten F. L. Golterman

The quenched approximation for QCD is, at present and in the foreseeable future, unavoidable in lattice calculations with realistic choices of the lattice spacing, volume and quark masses. In this talk, I review an analytic study of the effects of quenching based on chiral perturbation theory. Quenched chiral perturbation theory leads to quantitative insight

J. D. Brown, J. Creighton, R. B. Mann

We investigate the thermodynamical properties of black holes in (3+1) and (2+1) dimensional Einstein gravity with a negative cosmological constant. In each case, the thermodynamic internal energy is computed for a finite spatial region that contains the black hole. The temperature at the boundary of this region is defined by differentiating the energy with r

Lian Zheng, H. A. Fertig

Using the Kubo formula, we show explicitly that a non-interacting electron system can not behave like a Hall-insulator, {\it ie.,} a DC resistivity matrix $ρ_{xx}\rightarrow\infty$ and $ρ_{xy}=$finite in the zero temperature limit, as has been observed recently in experiment. For a strongly interacting electron system in a magnetic field, we illustrate, by c

P. Leboeuf, A. Mouchet

We compute the dispersion laws of chaotic periodic systems using the semiclassical periodic orbit theory to approximate the trace of the powers of the evolution operator. Aside from the usual real trajectories, we also include complex orbits. These turn out to be fundamental for a proper description of the band structure since they incorporate conduction pro

Antonio Coniglio, Patrizia Ruggiero, Marco Zannetti

The dependence of the scaling properties of the structure factor on space dimensionality, range of interaction, initial and final conditions, presence or absence of a conservation law is analysed in the framework of the large-N model for growth kinetics. The variety of asymptotic behaviours is quite rich, including standard scaling, multiscaling and a mixtur

R. G. M. van der Sman, M. F. M. Janssens

A Lattice Boltzmann scheme has been applied to the problem of heat and mass transport in packagings of cut flowers. The LB scheme, simulating convection-diffusion processes and heat and mass transfer between flowers and air flow, is described in detail. The objective of the research programme is to optimize the packaging design for improved flower quality. C

Andrew Kehler

It is claimed that a variety of facts concerning ellipsis, event reference, and interclausal coherence can be explained by two features of the linguistic form in question: (1) whether the form leaves behind an empty constituent in the syntax, and (2) whether the form is anaphoric in the semantics. It is proposed that these features interact with one of two t

Ezra Black, Fred Jelinek, John Lafferty, David M. Magerman

We describe a generative probabilistic model of natural language, which we call HBG, that takes advantage of detailed linguistic information to resolve ambiguity. HBG incorporates lexical, syntactic, semantic, and structural information from the parse tree into the disambiguation process in a novel way. We use a corpus of bracketed sentences, called a Treeba

David M. Magerman, Carl Weir

This paper describes Picky, a probabilistic agenda-based chart parsing algorithm which uses a technique called {\em probabilistic prediction} to predict which grammar rules are likely to lead to an acceptable parse of the input. Using a suboptimal search method, Picky significantly reduces the number of edges produced by CKY-like chart parsing algorithms, wh

David M. Magerman, Mitchell P. Marcus

This paper describes a natural language parsing algorithm for unrestricted text which uses a probability-based scoring function to select the &#34;best&#34; parse of a sentence. The parser, Pearl, is a time-asynchronous bottom-up chart parser with Earley-type top-down prediction which pursues the highest-scoring theory in the chart, where the score of a theo

Esther Koenig

The previously proposed semantic-head-driven generation methods run into problems if none of the daughter constituents in the syntacto-semantic rule schemata of a grammar fits the definition of a semantic head given in Shieber et al. 1990. This is the case for the semantic analysis rules of certain constraint-based semantic representations, e.g. Underspecifi

Arnon Dar, Jaques Goldberg, Michael Rudzsky

The enclosed paper was submitted for publication in Ap.J Lett. in February 1992. It has been rejected on the grounds that it predicts primordial Deuterium abundance which is contradicted by observations and because it disagreed with published analysis and conclusions of previous authors. However, in a recent article in NATURE (14 April 1994) Vol. 368 pp. 599

D. L. Band, L. A. Ford, J. L. Matteson, M. Briggs

We describe a Bayesian methodology to evaluate the consistency between the reported Ginga and BATSE detections of absorption features in gamma ray burst spectra. Currently no features have been detected by BATSE, but this methodology will still be applicable if and when such features are discovered. The Bayesian methodology permits the comparison of hypothes

J. Greiner, R. Egger, B. Aschenbach

We report the discovery of a new SNR in the \ros All-Sky-Survey data. The SNR has a nearly circular shape with a diameter of about 15 arcmin. The surface brightness is rather uniform over the remnant. The observed interstellar absorption suggests a distance of about 1.8$^{+1.4}_{-0.8}$ kpc. The X-ray emission appears to be of thermal origin with a plasma tem

Tsvi Piran

$γ$-ray bursts have baffled theorists ever since their accidental discovery at the sixties. We suggest that these bursts originate in merger of neutron star binaries, taking place at cosmological distances. These mergers release $\approx 10^{54}ergs$, in what are possibly the strongest explosions in the Universe. If even a small fraction of this energy is ch

Jane C. Charlton, Edwin E. Salpeter, Suzanne M. Linder

A break in the distribution function of Ly$α$ clouds (at a typical redshift of $2.5$) has been reported by Petitjean et al. (1993). This feature is what would be expected from a transition between pressure confinement and gravity confinement (as predicted in Charlton, Salpeter, and Hogan (1993)). The column density at which the feature occurs has been used t

Vladimir V. Kisil

One can introduce so-called {\em Plain Mechanics} having an {\bf operator realization}. Then the set of one-dimension representations of this operator realization may be identified with the Classical Mechanics. Different irreducible infinite-dimension representations may be recognized as Quantum Mechanics for different $\hbar$ (the Planck constant). It can b

I. Sarcevic, P. Valerio

We present results on rapidity and transverse momentum distributions of inclusive charm quark production in heavy-ion collisions at RHIC, including the next-to-leading order, $O(α_s^3)$, radiative corrections and the nuclear shadowing effect. We find the effective, nuclear K-factor to be $K(y)\approx 1.4$ for $\mid y\mid \leq 3$ in the rapidity distribution,

Xianzhe Dai, Daniel S. Freed

We study eta-invariants on odd dimensional manifolds with boundary. The dependence on boundary conditions is best summarized by viewing the (exponentiated) eta-invariant as an element of the (inverse) determinant line of the boundary. We prove a gluing law and a variation formula for this invariant. This yields a new, simpler proof of the holonomy formula fo

X. Zhang

We calculate the top quark loop corrections to the Zbb vertex in the chiral lagrangian of the dynamical electroweak symmetry breaking theory. We use the effective lagrangian based on coset space SU(2) X U(1) / U(1) with the gauge interactions switched off, so these corrections are directly related to the Physics associated with the heavy top quark and the ma