August 1994 arXiv papers — page 8

S. Viefers, F. Ravndal, T. Haugset

Thermodynamic properties of non-relativistic bosons and fermions in two spatial dimensions and without interactions are derived. All the virial coefficients are the same except for the second, for which the signs are opposite. This results in the same specific heat for the two gases. Existing equations of state for the free anyon gas are also discussed and s

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

The type-I simple Lie-superalgebras are $sl(m|n)$ and $osp(2|2n)$. We study the quantum deformations of their untwisted affine extensions $U_q(sl(m|n)^{(1)})$ and $U_q(osp(2|2n)^{(1)})$. We identify additional relations between the simple generators (``extra $q$-Serre relations") which need to be imposed to properly define $\uqgh$ and $U_q(osp(2|2n)^{(1)

Kei-Ichi Kondo, Pieter Maris

We have studied the chiral phase transition in three-dimensional QED in the presence of a Chern--Simons term for the gauge field. There exists a phase where the chiral symmetry is broken dynamically and we have determined the critical line for this symmetry breaking as a function of the effective coupling and the strength of the additional Chern--Simons term

Hiroshi Kunitomo, Makoto Sakaguchi, Akira Tokura

It is shown that the N-extended super $w_n$\ string can be obtained as a special class of vacua of both the N-extended super $w_{n+1}$\ string and the (N+1)-extended super $w_n$\ string. This hierarchy of super $w$\ string theories includes as subhierarchies both the superstring hierarchy given by Bastianelli, Ohta and Petersen and the $w$\ string hierarchy

Sean A. Hayward

Various properties of the Misner-Sharp spherically symmetric gravitational energy E are established or reviewed. In the Newtonian limit of a perfect fluid, E yields the Newtonian mass to leading order and the Newtonian kinetic and potential energy to the next order. For test particles, the corresponding Hajicek energy is conserved and has the behaviour appro

A. Csoto, K. Langanke, S. E. Koonin, T. D. Shoppa

We study the nonresonant part of the $^7$Be($p,γ$)$^8$B reaction using a three-cluster resonating group model that is variationally converged and virtually complete in the $^4$He+$^3$He+$p$ model space. The importance of using adequate nucleon-nucleon interaction is demonstrated. We find that the low-energy astrophysical $S$-factor is linearly correlated wit

Nathan Seiberg

Holomorphy of the superpotential and of the coefficient of the gauge kinetic terms in supersymmetric theories lead to powerful results. They are the underlying conceptual reason for the important non-renormalization theorems. They also enable us to study the exact non-perturbative dynamics of these theories. We find explicit realizations of known phenomena a

J. Baacke, T. Daiber

We present an evaluation of the fluctuation determinant which appears as a prefactor in the instanton transition rate for the two-dimensional Abelian Higgs model. The corrections are found to change the rate at most by a factor of 2 for 0.4 < M_W/M_H < 2.0.

Yu. M. Zinoviev

The new inversion formula for the Laplace transformation of the tempered distributions with supports in the closed positive semiaxis is obtained. The inverse Laplace transform of the tempered distribution is defined by means of the limit of the special distribution constructed from this distribution. The weak spectral condition on the Euclidean Green&#39;s f

Stefan Berceanu

A geometric characterization of transition amplitudes between coherent states, or equivalently, of the hermitian scalar product of holomorphic cross sections in the associated D - M tilda - module, in terms of the embedding of the cohe- rent state manifold M-tilda into a projective Hilbert space is proposed. Cohe- rent state manifolds endowed with a homogene

F. Franke, H. Fraas, A. Bartl

We analyze the experimental data from the search for new particles at LEP 100 and obtain mass bounds for the neutralinos of the Next--To--Minimal Supersymmetric Standard Model (NMSSM). We find that for $\tanβ\gsim 5.5$ a massless neutralino is still possible, while the lower mass bound for the second lightest neutralino corresponds approximately to that for

R. Aleksan, A. Le Yaouanc, L. Oliver, O. Pène

We point out that current estimates of form factors fail to explain the non-leptonic decays $B \to ψK(K^{\ast})$ and that the combination of data on the semi-leptonic decays $D \to K(K^{\ast})\ell ν$ and on the non-leptonic decays $B \to ψK(K^{\ast})$ (in particular recent po\-la\-ri\-za\-tion data) severely constrain the form (normalization and $q^2$ depend

D. Boyanovsky, H. J. de Vega, R. Holman, D. S-Lee

The non-equilibrium dynamics of the first stage of the reheating process, that is dissipation via particle production is studied in scalar field theories in the unbroken and in the broken symmetry phase. We begin with a perturbative study to one loop and show explicitly that the mechanism of dissipation via particle production cannot be explained with a simp

A. Yu. Dubin, A. B. Kaidalov, Yu. A. Simonov

The light-cone Hamiltonian is derived from the general gauge -- and Lorentz -- invariant expression for the $q\bar{q}$ Green&#39;s function, containing confinement via the area law for the Wilson loop.The resulting Hamiltonian contains in a nonadditive way contributions from quark and string degrees of freedom. Different limiting dynamical regimes of the sys

Edi Halyo

We show that supersymmetry can be broken mainly by hidden matter condensates in the observable matter direction in generic superstring models. This happens only when the fields whose VEVs give masses to hidden matter do not decouple at the condensation scale. We find how the parameters of the string model and the vacuum determine whether supersymmetry is bro

M. Ishii, T. Hatsuda

The hadronic screening mass at high temperature ($T$) in QCD$_4$ is examined on the basis of the QCD sum rules in (2+1) dimensions. Due to the magnetic gluon condensate at high $T$ which is expected to be nonvanishing, the screening mass deviates from the asymptotic value $2πT$. Also, the screening mass in the vector (pseudo-vector) channel turns out to be h

Tsuneo Suzuki, Sawut Ilyar, Yoshimi Matsubara, Tsuyoshi Okude

Monte-Carlo simulations of abelian projection of $T \neq 0$ pure lattice QCD show that 1) Polyakov loops written in terms of abelian link fields alone play a role of an order parameter of deconfinement transition, 2) the abelian Polyakov loops are decomposed into contributions from Dirac strings of monopoles and from photons, 3) vanishing of the abelian Poly

M. Fukugita, Y. Kuramashi, M. Okawa, A. Ukawa

We calculate both connected and disconnected contribution to the $π$-$N$ $σ$-term in quenched lattice QCD with Wilson quark action on a $12^3\times 20$ lattice at $β=5.7$. The latter is evaluated with the aid of the variant wall source method, which was previously applied successfully for extraction of $π$-$π$ scattering lengths and $η^\prime$ meson mass. We

Per Kraus, Frank Wilczek

We consider the modification of the formulas for black hole radiation, due to the self-gravitation of the radiation. This is done by truncating the coupled particle-hole system to a small set of modes, that are plausibly the most significant ones, and quantizing the reduced system. In this way we find that the particles no longer move along geodesics, nor is

Lajos Diósi

We enlist various motivations underlying the idea that von Neumann collapses occure permanently, spontaneously and even universally. In addition to the conceptual value of permanent reduction theory, we mention its important by-product promoting new quantum Monte-Carlo simulations of irrevesible quantum processes, especially in laser optics.

W. D. Heiss, R. G. Nazmitdinov

The classical trajectories of single particle motion in a Wodds-Saxon and a modified Nilsson potential are studied for axial quadrupole deformation. Both cases give rise to chaotic behaviour when the deformation in the Woods-Saxon and the l**2 term in the modified Nilsson potential are turned on. Important similarities, in particular with regard to the short

K. A. Kikoin, M. N. Kiselev, A. S. Mishchenko

Microscopic mechanism of forming the spin liquid of neutral fermions in Kondo lattices with nearly integer valence of the f-electrons in presented. It is shown that the competition between the Kondo scattering and the indirect exchange interaction can result in stabilization of a state with separated spin and charge excitations with a Fermi-type spectrum for

T. Nakajima, H. Aoki

Spin-wave excitation mode from the spin-polarized ground state in the fractional quantum Hall liquid with odd fractions ($ν=1/3,1/5$) numerically obtained by the exact diagonalization of finite systems is shown to be accurately described, for wavelengths exceeding the magnetic length, in terms of the composite-fermion mean-field approximation for the spin-wa

Mark Burgess, Margaret Carrington

Recently it has been suggested that junctions between materials with different parity violating properties would be characterized by diffusion layers, analogous to those in the p-n junction. This remark is amplified by a fuller investigation of two related parity violating effective Lagrangians, which possess a kind of duality. It is shown that gauge invaria

E. Caputo, S. Sello, ; V. Marcolongo

The paper describes the application of some numerical techniques to analyze and to characterize the observed dynamical behaviour of fluidized bed systems. The preliminary results showed clearly that the dynamics of the considered process can be nonrecurrent and governed by chaotic deterministic rules rather than by stochastic ones. This significant conclusio

Oliver Christ

The paper describes the architecture of an integrated and extensible corpus query system developed at the University of Stuttgart and gives examples of some of the modules realized within this architecture. The modules form the core of a corpus workbench. Within the proposed architecture, information required for the evaluation of queries may be derived from

Andrew Fordham, Matthew Crocker

This paper is an attempt to bring together two approaches to language analysis. The possible use of probabilistic information in principle-based grammars and parsers is considered, including discussion on some theoretical and computational problems that arise. Finally a partial implementation of these ideas is presented, along with some preliminary results f

Paul John King

A description is an entity that can be interpreted as true or false of an object, and using feature structures as descriptions accrues several computational benefits. In this paper, I create an explicit interpretation of a typed feature structure used as a description, define the notion of a satisfiable feature structure, and create a simple and effective al

Andrew Ulmer, Ralph A. M. J. Wijers

We examine the width of the gamma-ray burst (GRB) luminosity function through the distribution of GRB peak count rates, C$_{\rm{peak}}$, as detected by BATSE (\cite{batse:93}). In the context of galactic corona spatial distribution models, we attempt to place constraints on the characteristic width of the luminosity function by comparing the observed intensi

Ralph A. M. J. Wijers, Bohdan Paczyński

The recent discovery that faint gamma-ray bursts are stretched in time relative to bright ones has been interpreted as support for cosmological distances: faint bursts have their durations redshifted relative to bright ones. It was pointed out, however, that the relative time stretching can also be produced by an intrinsic correlation between duration and lu

M. M. Briley, R. A. Bell, J. E. Hesser, G. H. Smith

Abundance patterns of the elements C, N, and O are sensitive probes of stellar nucleosynthesis processes and, in addition, O abundances are an important input for stellar age determinations. Understanding the nature of the observed distribution of these elements is key to constraining protogalactic star formation history. Patterns deduced from low-resolution

Andrew S. Wilson, Edward J. M. Colbert

The recent development of unified theories of active galactic nuclei (AGN) has indicated that there are two physically distinct classes of these objects - radio-loud and radio-quiet. The primary observational distinctions between the two types are: (1) The radio-loud objects produce large scale radio jets and lobes, with the kinetic power of the jets being a

H. Saleur, S. Skorik, N. P. Warner

We consider the sine-Gordon model on a half-line, with an additional potential term of the form $-M\cos{β\over 2}(φ-φ_0)$ at the boundary. We compute the classical time delay for general values of $M$, $β$ and $φ_0$ using $τ$-function methods and show that in the classical limit, the method of images still works, despite the non-linearity of the problem. We

Scott Chapman, Pierre Scotto, Ulrich Heinz

Using two specific models and a model-independent formalism, we show that in addition to the usual quadratic ``side&#39;&#39;, ``out&#39;&#39; and ``longitudinal&#39;&#39; terms, a previously neglected ``out-longitudinal&#39;&#39; cross term arises naturally in the exponent of the two-particle correlator. Since its effects can be easily observed, such a term

M. Fontannaz

We show how the parton distributions in the photon can be accurately measured in the photoproduction of large-pt jets at HERA. A short review is given of the beyond Leading Logarithm formalism for the photon structure function, with a discussion of the factorization scheme and of the non-perturbative input.

Peter Cho, Elizabeth Simmons

The triple gluon field strength operator $G^3$ represents the only genuinely gluonic CP conserving term which can appear at dimension-6 within an effective strong interaction Lagrangian. Previous studies of this operator have revealed that its effect on gluon scattering is surprisingly difficult to detect. In this article, we analyze the impact of $G^3$ upon

Dale Gerdemann, Paul John King

In this paper, we argue that type inferencing incorrectly implements appropriateness specifications for typed feature structures, promote a combination of type resolution and unfilling as a correct and efficient alternative, and consider the expressive limits of this alternative approach. Throughout, we use feature cooccurence restrictions as illustration an

Azusa Yamaguchi, Akio Sugamoto

The baryogenesis is reanalyzed based on the model by A.G.Cohen et al., in which the lepton number, generated by the neutrinos' scattering from the bubble walls appearing in the development of the electroweak phase transition, is converted to the baryon number excess through the sphaleron transition. A formula obtained in this paper on the lepton number produ

V. Barger, E. Mirkes, R. J. N. Phillips, T. Stelzer

We present the first calculation of $Z+4$ jet production with heavy quark flavor identification at the Tevatron $p\bar p$ collider. The $Z + 4$ jet channel is especially interesting as a normalizer for the $W +4$ jet background to top quark signals, as a background to a possible $t\to cZ$ flavor-changing neutral-current (FCNC) decay signal, and as a backgrou

S. Chaudhuri, J. Polchinski

We consider the continuum string theory corresponding to the Marinari-Parisi supersymmetric matrix model. We argue that the world-sheet physics is exotic, and different from any known supersymmetric string theory. The embedding superspace coordinates become disordered on the world-sheet, but because of the noncompactness of the embedding time the disorder be

Norma Mankoč Borštnik

In a space of d $(d > 5) $ ordinary and d Grassmann coordinates, fields manifest in an ordinary four-dimensional subspace as spinor (1/2, 3/2), scalar, vector or tensor fields with the corresponding charges, according to two kinds of generators of the Lorentz transformations in the Grassmann space. Vielbeins and spin connections define gauge fields-gravitati

C. H. Oh, K. Singh

We give field theoretic realizations of both the $q$-Heisenberg and the $q$-Virasoro algebra. In particular, we obtain the operator product expansions among the current and the energy momentum tensor obtained using the Sugawara construction.

A. B. Balantekin

Astrophysical implications of neutrino mass and mixings are discussed. The status of solar and atmospheric neutrino problems, and recent developments concerning nuclear physics input to solar models and solar opacities are reviewed. Implications of neutrino mass and mixings in supernova dynamics are explored. The effects of supernova density fluctuations in

C. A. Dominguez, M. Loewe, J. S. Rozowsky

The electromagnetic form factor of the pion in the space-like region, and at finite temperature, $F_π(Q^{2},T)$, is obtained from a QCD Finite Energy Sum Rule. The form factor decreases with increasing T, and vanishes at some critical temperature, where the pion radius diverges. This divergence may be interpreted as a signal for quark deconfinement.

M. Beneke

This talk reports on various aspects of the divergence of perturbative expansions in the context of matching QCD onto heavy quark effective theory. Implications for exclusive and inclusive decays of heavy mesons are discussed.

Piotr H. Chankowski

Combining the constraints coming from the ~$M_W$ ~measurements and the unsuccesful search for the Higgs boson at LEP we determine in the framework of MSSM the allowed mass regions for the lighter scalar partner of the top quark. For a heavy top quark particularily strong bounds are obtained for low values of ~$\tanβ\equiv v_2/v_1$ ~and light bottom squark.

A. D. Speliotopoulos

The interaction of classical gravitational waves (GW) with matter is studied within a quantum mechanical framework. The classical equations of motion in the long wave-length limit is quantized and a Schroedinger equation for the interaction of GW with matter is proposed. Due to its quadrapole nature, the GW interacts with matter by producing squeezed quantum

David Atwood, Alex Kagan, Tom Rizzo

We explore the influence of an anomalous chromomagnetic moment, $κ$, onthe production characteristics of top quark pairs at the Tevatron. We find that for top quarks in the 170 GeV mass range, present searches are probing values of $κ$ of order ${1 \over 3}$. For $κ$&#39;s in this range we find that significant enhancements in the both the $q \bar q,~gg \to

S. Tominaga, H. Yoneyama

We study finite size effects of the d=3 $XY$ model in terms of the chiral perturbation theory. We calculate by Monte Carlo simulations physical quantities which are, to order of $(1/L)^2$, uniquely determined only by two low energy constants. They are the magnetization and the helicity modulus (or the Goldstone boson decay constant) in infinite volume. We al

A. A. Kirillov, V. N. Melnikov

The problem of construction of a general ihomogeneous solution of $D$-dimensional Einstein equations in the vicinity of a cosmological singularity is considered. It is shown that near the singularity a local behavior of metric functions is described by a billiard on a space of a constant negative curvature. The billiard is shown to have a finite volume and c

Alan D. Rendall

The nature of the initial singularity in spatially compact plane symmetric scalar field cosmologies is investigated. It is shown that this singularity is crushing and velocity dominated and that the Kretschmann scalar diverges uniformly as it is approached. The last fact means in particular that a maximal globally hyperbolic spacetime in this class cannot be

S. K. Murthy, S. Kasif, S. Salzberg

This article describes a new system for induction of oblique decision trees. This system, OC1, combines deterministic hill-climbing with two forms of randomization to find a good oblique split (in the form of a hyperplane) at each node of a decision tree. Oblique decision tree methods are tuned especially for domains in which the attributes are numeric, alth

T. Kitani, Y. Eriguchi, M. Hara

Information extraction is the task of automatically picking up information of interest from an unconstrained text. Information of interest is usually extracted in two steps. First, sentence level processing locates relevant pieces of information scattered throughout the text; second, discourse processing merges coreferential information to generate the outpu

A. J. Grove, J. Y. Halpern, D. Koller

Given a knowledge base KB containing first-order and statistical facts, we consider a principled method, called the random-worlds method, for computing a degree of belief that some formula Phi holds given KB. If we are reasoning about a world or system consisting of N individuals, then we can consider all possible worlds, or first-order models, with domain {

Francisco Dominguez-Adame, Angel Sanchez, Enrique Diez

We theoretically study electron transport in disordered, quantum-well based, semiconductor superlattices with structural short-range correlations. Our system consists of equal width square barriers and quantum wells with two different thicknesses. The two kinds of quantum wells are randomly distributed along the growth direction. Structural correlations are

G. Gompper, M. Hennes

The dynamic structure factor $G({\bf k},ω)$ is studied in a time-dependent Ginzburg-Landau model for microemulsion and sponge phases in thermal equilibrium by field-theoretic perturbation methods. In bulk contrast, we find that for sufficiently small viscosity $η$, the structure factor develops a peak at non-zero frequency $ω$, for fixed wavenumber $k$ with

Rosario Fazio, F. W. J. Hekking, A. A. Odintsov

We study the Josephson effect through a one-dimensional system of interacting electrons, connected to two superconductors by tunnel junctions. The interactions are treated in the framework of the one-channel Luttinger model. At zero temperature, the Josephson critical current is found to decay algebraically with increasing distance between the junctions. The

George A. Kiraz

This paper demonstrates how a (multi-tape) two-level formalism can be used to write two-level grammars for Arabic non-linear morphology using a high level, but computationally tractable, notation. Three illustrative grammars are provided based on CV-, moraic- and affixational analyses. These are complemented by a proposal for handling the hitherto computatio

A. Lambert, R. Lima

In relation to spatiotemporal intermittency, as it can be observed in coupled map lattices, we study the stability of different wavelengths in competition. Introducing a two dimensional map, we compare its dynamics with the one of the whole lattice. We conclude a good agreement between the two. The reduced model also allows to introduce an order parameter wh

J. Pantaleone

In a recent paper I concluded that the neutrino background is important for calculating neutrino flavor evolution in supernovae, and including it weakens the connection between r-process nucleosynthesis and cosmologically relevant neutrino masses. Comments on this paper have been posted to this bulletin board; one by J. Cline and the other by Y.Z. Qian and G

Andrew Gould

I derive a general expression for the optical depth $τ$ for gravitational lensing of stars in a disk by Massive Compact Objects (Machos) in the same disk. For the more restricted case where the disk is self-gravitating and the stars and Machos have the same distribution function, I find $τ= 2\VEV{v^2}/c^2\sec^2 i$ where $\VEV{v^2}$ is the mass-weighted verti

Edward L. Wright

The index $n$ of a power law power spectrum of primordial density fluctuations, $P(k) \propto k^n$, has been estimated using many different techniques. The most precise compare the COBE DMR large angular scale $ΔT$ to the amplitude of the large scale structure, but these are also the most model-dependent. The COBE DMR $ΔT$ has also been compared to the degre

Edward L. Wright

The observations of all three COBE instruments are examined for the effects of dark matter. The anisotropy measured by the DMR, and especially the degree-scale ground- and balloon-based experiments, is only compatible with large-scale structure formation by gravity if the Universe is dominated by non-baryonic dark matter. The FIRAS instrument measures the to

Robert Crittenden

The polarization of the CMB offers a potentially valuable probe of the physics of the early universe, specifically of the velocity of the photon-baryon fluid on the last scattering surface. Here we discuss qualitatively the correlations that arise between the temperature anisotropies and polarization of the CMB and how they might be observed.