April 1993 arXiv papers — page 4

Anthony Bloch, P. S. Krishnaprasad, Jerrold E. Marsden, Tudor S. Ratiu

The main goal of this paper is to prove that if the energy-momentum (or energy-Casimir) method predicts formal instability of a relative equilibrium in a Hamiltonian system with symmetry, then with the addition of dissipation, the relative equilibrium becomes spectrally and hence linearly and nonlinearly unstable. The energy-momentum method assumes that one

Roger Temam, Shouhong Wang

The Navier--Stokes equations for incompressible flows past a two--dimensional sphere are considered in this article. The existence of an inertial form of the equations is established. Furthermore for the first time for fluid equations, we derive an upper bound on the dimension of the differential system (inertial manifold) which fully reproduces the infinite

Mark W Jacobs, Eric V Linder, Robert V Wagoner

We study scalar perturbations to a Robertson-Walker cosmological metric in terms of a pseudo-Newtonian potential, which emerges naturally from the solution of the field equations. This potential is given in terms of a Green function for matter density fluctuations of arbitrary amplitude whose time and spatial dependence are assumed known. The results obtaine

Vassil Kanev

With every smooth, projective algebraic curve $\tilde{C}$ with involution $σ:\tilde{C}\longrightarrow \tilde{C}$ without fixed points is associated the Prym data which consists of the Prym variety $P:=(1-σ)J(\tilde{C})$ with principal polarization $Ξ$ such that $2Ξ$ is algebraically equivalent to the restriction on $P$ of the canonical polarization $Θ$ of th

I. Vattulainen, K. Kankaala, J. Saarinen, T. Ala-Nissila

We present results of an extensive test program of a group of pseudorandom number generators which are commonly used in the applications of physics, in particular in Monte Carlo simulations. The generators include public domain programs, manufacturer installed routines and a random number sequence produced from physical noise. We start by traditional statist

Lajos Diosi

Based on the standard statistical interpretation of mixed quantum states, a unique family of consistent histories has been constructed for the quantum Brownian motion in the Caldeira-Leggett reservoir. Analytic solutions have been shown in the Markovian regime: they are uniquely defined coherent wave packets travelling near classical trajectories.

M. Hasenbusch, K. Pinn, K. Rummukainen

We study the use of effective transfer matrices for the numerical computation of masses (or correlation lengths) in lattice spin models. The effective transfer matrix has a strongly reduced number of components. Its definition is motivated by a renormalization group transformation of the full model onto a 1-dimensional spin model. The matrix elements of the

Heiko Rieger, A. P. Young

The phase transition of the three--dimensional random field Ising model with a discrete ($\pm h$) field distribution is investigated by extensive Monte Carlo simulations. Values of the critical exponents for the correlation length, specific heat, susceptibility, disconnected susceptibility and magnetization are determined simultaneously via finite size scali

Andrei Linde, Arthur Mezhlumian

If the Universe contains at least one inflationary domain with a sufficiently large and homogeneous scalar field, then this domain permanently produces new inflationary domains of all possible types. We show that under certain conditions this process of the self-reproduction of the Universe can be described by a stationary distribution of probability, which

Michael Beyer

The CALTECH gamma-transition experiment testing time reversal symmetry via the E2/M1 mulipole mixing ratio of the 122 keV gamma-line in Fe-57 has already been performed in 1977. Extending an earlier analysis in terms of an effective one-body potential, this experiment is now analyzed in terms of effective one boson exchange T-odd P-even nucleon nucleon poten

M. Elaasar, R. Madey, W. M. Zhang, J. Schambach

We measured the first azimuthal distributions of triple--differential cross sections of neutrons emitted in heavy-ion collisions, and compared their maximum azimuthal anisotropy ratios with Boltzmann--Uehling--Uhlenbeck (BUU) calculations with a momentum-dependent interaction. The BUU calculations agree with the triple- and double-differential cross sections

P. Mayr, S. Stieberger

We investigate the dependence of the gauge couplings on the dilaton field in string effective theories at the one--loop level. First we resolve the discrepancies between statements based on symmetry considerations and explicit calculations in string effective theories on this subject. A calculation of the relevant one--loop scattering amplitudes in string th

J. Mickelsson, R. Percacci

We generalize to dimension $p>1$ the notion of string structure and discuss the related obstruction. We apply our results to a model of bosonic $p$-branes propagating on a principal $G$-bundle, coupled to a Yang--Mills field and an antisymmetric tensor field and in the presence of a Wess-Zumino term in the Lagrangian. We construct the quantization line bundl

K. Ranganathan, H. Sonoda, B. Zwiebach

Motivated by the problem of background independence of closed string field theory we study geometry on the infinite vector bundle of local fields over the space of conformal field theories (CFT's). With any connection we can associate an excluded domain $D$ for the integral of marginal operators, and an operator one-form $ω_μ$. The pair $(D, ω_μ)$ determ

Carl M. Bender, Kimball A. Milton

The connection between a Taylor series and a continued-fraction involves a nonlinear relation between the Taylor coefficients $\{ a_n \}$ and the continued-fraction coefficients $\{ b_n \}$. In many instances it turns out that this nonlinear relation transforms a complicated sequence $\{a_n \}$ into a very simple one $\{ b_n \}$. We illustrate this simplific

P. Fendley, H. Saleur, Al. B. Zamolodchikov

We study the spectrum, the massless S-matrices and the ground-state energy of the flows between successive minimal models of conformal field theory, and within the sine-Gordon model with imaginary coefficient of the cosine term (related to the minimal models by ``truncation''). For the minimal models, we find exact S-matrices which describe the scatt

P. Fendley, H. Saleur, Al. B. Zamolodchikov

The massless flow between successive minimal models of conformal field theory is related to a flow within the sine-Gordon model when the coefficient of the cosine potential is imaginary. This flow is studied, partly numerically, from three different points of view. First we work out the expansion close to the Kosterlitz-Thouless point, and obtain roaming beh

Eric Raiten

Cosmological solutions of the beta function equations for the background fields of the closed bosonic string are investigated at the one-loop level. Following recent work of Kostelecky and Perry, it is assumed that the spatial sections of the space-time are conformally flat. Working in the sigma-model frame, the non-trivial tachyon potential is utilized to d

V. Alan Kostelecký, Michael Martin Nieto

Proposed close-encounter solar probes (Vulcan and Solar Probe) are planned to have highly eccentric orbits, with a perihelion of about $4R_S$ and an inclination close to $90^\circ$ out of the plane of the ecliptic. We show this could allow at least an order-of-magnitude improvement in the present directly measured limit on the photon mass.

Zvi Bern

Recent progress in the computation of one-loop gluon amplitudes is reviewed. These methods were originally derived from superstring theory and are significantly more efficient than conventional Feynman rules. With these methods, explicit computations can be performed beyond those achieved by traditional methods.

O. J. P. Eboli, M. C. Gonzalez-Garcia, S. F. Novaes

We analyze the production and detection of the Higgs boson in the next generation of linear $e^+e^-$ colliders operating in the $eγ$ mode. In particular, we study the production mechanism $e + γ\rightarrow e γγ\rightarrow e + H$, where one photon is generated via the laser backscattering mechanism, while the other is radiated via the usual bremsstrahlung pro

G. Lazarides, Q. Shafi

We propose a new realization of the chaotic inflationary scenario in which the scalar field responsible for inflation also spontaneously breaks the underlying gauge symmetry at a superheavy scale $\sim 10^{15} - 10^{17}\; GeV$. A possible framework is provided by the superstring inspired gauge models, in which case several predictions are essentially model i

Makoto Oka

Dynamics of two-Skyrmion systems is studied in the quasistatic approach. The quasistatic approach enables us to formulate the collective coordinate quantization of two-Skyrmion systems consistently with the 1/Nc expansion. By constructing quasistatic field configurations for largely separated two Skyrmions, their energies are computed for three independent r

Rajan Gupta, David Daniel, Jeffrey Grandy

We present an investigation of various gauge invariant definitions of the $q\bar q$ Bethe-Salpeter (BS) amplitude for mesons in lattice QCD, and compare them to the Coulomb and Landau gauge BS amplitudes. We show that the gauge invariant BS amplitude is considerably broadened by the use of ``fat'' gauge links (constructed by smearing the links of the

J. Tinka Gammel F. Guo, D. Guo, K. C. Ung, S. Mazumdar

We study the pairing within the Peierls-Hubbard Model for electron- and hole-doped analogs of C$_{60}$ accessible to exact diagonalization techniques (cube, truncated tetrahedron, {\it etc.}). We discuss how inclusion of electron-phonon interactions can substantially modify the conclusions about pairing obtained when this coupling is neglected. We also discu

I. Dolgachev, M. Kapranov

A cubic surface in $P^3$ is known to contain 27 lines, out of which one can form 36 Schlafli double - sixes i.e., collections $l_1,...,l_6, l'_1,..., l'_6\}$ of 12 lines such that each $l_i$ meets only $l'_j, j\neq i$ and does not meet $l_j, j\neq i$. In 1881 F. Schur proved that any double - six gives rise to a certain quadric $Q$ , called Schur

V. Sadov

We study the nonunitary representations of N=2 Super Virasoro algebra for the rational central charges c<3. The resolutions for the irreducible representations of N=2 SVir in terms of the &#34;2-d gravity modules&#34; are obtained and their characters are computed. The correspondence between the N=2 nonunitary &#34;minimal&#34; models and the Virasoro minima

N. D. Hari Dass, G. Subramoniam

Analytic variational techniques for lattice gauge theories based on the Rayleigh-Ritz(RR) method were previously developed for euclidean SU(2) gauge theories in 3 and 4 dimensions. Their extensions to SU(3) gauge theory including applications to correlation functions and mass gaps are presented here.

Garvin Melles

Let V be the universe of sets and V_α the sets of rank \leqα. We develop some axiom schemata for set theory based on the following three assumptions: 1. V \models ZFC 2. V is large with respect to the class of ordinals 3. V is large with respect to each of the V_α

Garvin Melles, Saharon Shelah

We prove that for a stable theory $T,$ if $M$ is a saturated model of $T$ of cardinality $λ$ where $λ> \big|T\big|,$ then $Aut(M)$ has a dense free subgroup on $2^λ$ generators. This affirms a conjecture of Hodges.

A. Gorsky, N. Nekrasov

We obtain integral representations for the wave functions of Calogero-type systems,corresponding to the finite-dimentional Lie algebras,using exact evaluation of path integral.We generalize these systems to the case of the Kac-Moody algebras and observe the connection of them with the two dimensional Yang-Mills theory.We point out that Calogero-Moser model a

A. Galperin, E. Sokatchev

We propose a new formulation of the $D=3$ type II superstring which is manifestly invariant under both target-space $N=2$ supersymmetry and worldsheet $N=(1,1)$ super reparametrizations. This gives rise to a set of twistor (commuting spinor) variables, which provide a solution to the two Virasoro constraints. The worldsheet supergravity fields are shown to p

M. Alford, M. Gleiser

We study analytically and numerically the decay of a metastable phase in (2+1)-dimensional classical scalar field theory coupled to a heat bath, which is equivalent to two-dimensional Euclidean quantum field theory at zero temperature. By a numerical simulation we obtain the nucleation barrier as a function of the parameters of the potential, and compare it

G. L. Kane

In addition to the very good theoretical motivations for supersymmetry, there are now at least nine phenomenological indications that nature is supersymmetric. All are indirect, so more is better. They are enumerated here. Some discussion is also given of models, of when and where superpartners might be directly detected, and of why the scale of supersymmetr

Kevin Cahill

By attaching basis vectors to the components of matter fields, one may render free action densities fully covariant. Both the connection and the tetrads are quadratic forms in these basis vectors. The metric of spacetime, which is quadratic in the tetrads, is then quartic in the basis vectors.

Predrag Cvitanović, Per E. Rosenqvist

We propose a new type of approximation to quantum determinants, ``quantum Fredholm determinant&#34;, and conjecture that, compared to the quantum Selberg zeta functions derived from Gutzwiller semiclassical trace formulas, such determinants have a larger domain of analyticity for Axiom A hyperbolic systems. The conjecture is supported by a numerical investig

Michael S. Turner

In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge---a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for---and the fundamentals of---inflationary cosmology, particularly emphasizing the quantum origin of metric (density and

Michael J. Tripicco, Ben Dorman, Roger A. Bell

We present a study of the stellar content of the open cluster M67. We have computed new evolutionary sequences of stellar models with solar abundance that cover all phases of evolution from the Zero-Age Main Sequence to the bright end of the Asymptotic Giant Branch (AGB). We examine the fit between the calculated and the observed red giant branch (RGB) in pa

Reyer Sjamaar

I prove the existence of slices for an action of a reductive complex Lie group on a Kähler manifold at certain orbits, namely those orbits that intersect the zero level set of a momentum map for the action of a compact real form of the group. I give applications of this result to symplectic reduction and geometric quantization at singular levels of the momen

P. Candelas, E. Derrick, L. Parkes

We describe the mirror of the Z orbifold as a representation of a class of generalized Calabi-Yau manifolds that can be realized as manifolds of dimension five and seven. Despite their dimension these correspond to superconformal theories with $c=9$ and so are perfectly good for compactifying the heterotic string to the four dimensions of space-time. As a ch

Takashi Mishima, Akika Nakamichi

The global structure of 1 + 1 dimensional compact Universe is studied in two-dimensional model of dilaton gravity. First we give a classical solution corresponding to the spacetime in which a closed time-like curve appears, and show the instability of this spacetime due to the existence of matters. We also observe quantum version of such a spacetime having c

Dave Bayer, David Mumford

This paper is a survey of computational issues in algebraic geometry, with particular attention to the theory of Grobner bases and the regularity of an algebraic variety. 1. A geometric introduction to Grobner bases. 2. An algebraic introduction to Grobner bases. 3. Bounds in algebraic geometry, and regularity and complexity questions. 4. Applications.

D. V. Ahluwalia, M. B. Johnson, T. Goldman

This version corrects an inportant typographical error in Eq. 17. COMMENTS, FOR THE RECORD: A referees reoprt from Phys. Rev. Lett. read in part ``The first named author has appreciated my exceptionally long report. He has read and well assimilated the literature I suggested. Congratulations! This very new version of the manuscript has now three authors and

D. V. Ahluwalia, T. Goldman

By carefully studying the (1,0)+(0,1) representation space for massive particles we point to the existence of certain inherent tachyonic dispersion relations: E^2= p^2-m^2. We put forward an interpretation that exploits these ``negative mass squared&#39;&#39; solutions; rotational invariance is spontaneously broken. Relevance of these results to the vortices

E. W. Mielke, F. Gronwald, Y. N. Obukhov, R. Tresguerres

It is shown that gravity on the line can be described by the two dimensional (2D) Hilbert-Einstein Lagrangian supplemented by a kinetic term for the coframe and a translational {\it boundary} term. The resulting model is equivalent to a Yang-Mills theory of local {\it translations} and frozen Lorentz gauge degrees. We will show that this restricted Poincaré

M. A. Semenov-Tian-Shansky

The Heisenberg double of a Hopf algebra may be regarded as a quantum analogue of the cotangent bundle of a Lie group. Quantum duality principle describes relations between a Hopf algebra, its dual, and their Heisenberg double in a way which extends both the theory of coadjoint orbits and the classical Fourier transform. We also describe the twisted Heisenber

Gerhard Fasol, Hiroyuki Sakaki

We show that a quantum wire device with spin splitting can work as an active spin polarizer. Hot electrons in one `spin&#39; subband (e.g. `spin-up&#39;) may pass such a device with weak electron pair scattering, while electrons in the opposite subband (`spin-down&#39;) may have high conversion probability into the `spin-up&#39; subband, resulting in spin po

Vladimir Privman

A model of &#34;hot&#34;-dimer deposition in one dimension, introduced by Pereyra and Albano, is modified to have an unbounded dissociation range. The resulting dynamical equations are solved exactly. A related k-mer dissociation model is also introduced and its solution obtained as a quadrature.

J. Binney, S. Tremaine

This paper contains all known errata in the book &#34;Galactic Dynamics&#34;.

I. V. Volovich

A new model of bosonic strings is considered. An action of the model is the sum of the standard string action and a term describing an interaction of a metric with a linear (affine) connection. The Lagrangian of this interaction is an arbitrary analytic function $f(R)$ of the scalar curvature. This is a classically integrable model. The space of classical so

H. Ishikawa, M. Kato

The discrete states in the $c=1$ string are shown to be the physical states of a certain topological sigma model. We define a set of new fields directly from $c=1$ variables, in terms of which the BRST charge and energy-momentum tensor are rewritten as those of the topological sigma model. Remarkably, ground ring generator $x$ turns out to be a coordinate of

Aric Hagberg, Ehud Meron

Domain walls in equilibrium phase transitions propagate in a preferred direction so as to minimize the free energy of the system. As a result, initial spatio-temporal patterns ultimately decay toward uniform states. The absence of a variational principle far from equilibrium allows the coexistence of domain walls propagating in any direction. As a consequenc

Francois Gieres, Stefan Theisen

Starting from superdifferential operators in an $N=1$ superfield formulation, we present a systematic prescription for the derivation of classical $N=1$ and $N=2$ super W-algebras by imposing a zero-curvature condition on the connection of the corresponding first order system. We illustrate the procedure on the first non-trivial example (beyond the $N=1$ sup

Changhyun Ahn

We rewrite $ N=2$ quantum super $W_{3}$ algebra, a nonlinear extended $N=2$ super Virasoro algebra, containing one additional primary superfield of dimension $2$ which has no $U(1)$ charge, besides the super stress energy tensor of dimension $1$ in $N=2$ superspace. The free superfield realization of this algebra is obtained by two $N=2$ chiral fermionic sup

Jiang Liu, Gino Segre

It is shown that wave function renormalization can introduce an important contribution to the generation of baryon and lepton number asymmetries by heavy particle decay. These terms, omitted in previous analyses, are of the same order of magnitude as the standard terms. A complete cancellation of leading terms can result in some interesting cases.

I. Hauser, F. J. Ernst

Following an idea close to one given by C. G. Torre (private communication), we prove that Riemannian spaces (M,g) and (M,h) that are related by a Gurses type (b) transformation [M. Gurses, Phys. Rev. Lett. 70, 367 (1993)] or, equivalently, by a Torre-Anderson generalized diffeomorphism [C. G. Torre and I. M. Anderson, Phys. Rev. Lett. xx, xxx (1993)] are ne

Dingping Li

We derive the braid relations of the charged anyons interacting with a magnetic field on Riemann surfaces. The braid relations are used to calculate the quasiparticle&#39;s spin in the fractional quantum Hall states on Riemann surfaces. The quasiparticle&#39;s spin is found to be topological independent and satisfies physical restrictions.

Antoine Georges, Gabriel Kotliar, Werner Krauth

We study a two-band Hubbard model in the limit of infinite dimensions, using a combination of analytical methods and Monte-Carlo techniques. The normal state is found to display various metal to insulators transitions as a function of doping and interaction strength. We derive self-consistent equations for the local Green&#39;s functions in the presence of s

Emil Martinec

The causal boundary of string propagation -- defined as the hypersurface in loop space bordering the timelike(spacelike) domains in which two successive measurements of the string field do(do not) interfere with one another -- is argued to be $0=\int dσ\bigl(δX(σ)\bigr)^2 = \sum_{\ell=-\infty}^\infty δx^μ_{-\ell}δx_{μ\ell}.$ Some possible consequences are di

A. Alan Middleton, Ned S. Wingreen

(WORDS: QUANTUM DOTS, COLLECTIVE TRANSPORT, PHYSICAL EXAMPLE OF KPZ) Collective charge transport is studied in one- and two-dimensional arrays of small normal-metal dots separated by tunnel barriers. At temperatures well below the charging energy of a dot, disorder leads to a threshold for conduction which grows linearly with the size of the array. For short

A. C. Davis, A. P. Martin

This paper has been heavily revised, the final results now being contained in hep-ph/9311202 and hep-ph/9311203.

S. Aoki, H. Hirose, Y. Kikukawa

Property of charged fermion states is investigated in the quenched U(1) chiral Wilson-Yukawa model. Fitting the charged fermion propagator with a single hyperbolic cosine does not yield reliable results. On the other hand the behavior of the propagator including large lattice size dependence is well described by the large Wilson-Yukawa coupling expansion, pr

D. Klakow, G. Welke, W. Bauer

We consider the dependence of collective flow on the nuclear surface thickness in a Boltzmann--Uehling--Uhlenbeck transport model of heavy ion collisions. Well defined surfaces are introduced by giving test particles a Gaussian density profile of constant width. Zeros of the flow excitation function are as much influenced by the surface thickness as the nucl

J. A. McNeil, C. E. Price

We study a hybrid chiral model for the nucleon based on the linear sigma model with explicit quarks. We solve the model using a Fock-space configuration consisting of three quarks plus three quarks and a pion as the ground state ansatz in place of the ``hedgehog&#39;&#39; ansatz. We minimize the expectation value of the chiral hamiltonian in this ground stat

P. A. Henning, H. Umezawa

For thermal systems, standard perturbation theory breaks down because of the absence of stable, observable asymptotic states. We show, how the introduction of {\it statistical} quasi-particles (stable, but not observable) gives rise to a consistent description. Statistical and spectral information can be cleanly separated also for interacting systems.

P. A. Henning, H. Umezawa

The spectral function of pions interacting with a gas of nucleons and Delta-33-resonances is investigated using the formalism of Thermo Field Dynamics. After a discussion of the zero Delta-width approximation at finite temperature, we take into account a constant width of the resonance. Apart from a full numerical calculation, we give analytical approximatio

Michael Martin Nieto

After reviewing the role of phase in quantum mechanics, I discuss, with the aid of a number of unpublished documents, the development of quantum phase operators in the 1960&#39;s. Interwoven in the discussion are the critical physics questions of the field: Are there (unique) quantum phase operators and are there quantum systems which can determine their nat

J. A. Dixon, R. Minasian

Supersymmetry transformations are a kind of square root of spacetime translations. The corresponding Lie superalgebra always contains the supertranslation operator $ δ= c^α σ^μ_{α\dot β} {\overline c}^{\dot β} (ε^μ)^† $. We find that the cohomology of this operator depends on a spin-orbit coupling in an SU(2) group and has a quite complicated structure. This

A. Klemm, S. Theisen

We consider a class of Calabi-Yau compactifications which are constructed as a complete intersection in weighted projective space. For manifolds with one Kähler modulus we construct the mirror manifolds and calculate the instanton sum.

Rashmi Ray, B. Sakita

Starting from a system of planar electrons in a strong magnetic field normal to the plane, interacting with perturbing electromagnetic fields, an effective Lagrangian for the fermions in the lowest Landau level (L.L.L.) has been derived. By choosing a suitable background electrostatic potential, an incompressible droplet of these electrons is constructed. Th

A. P. Balachandran, G. Bimonte, K. S. Gupta, G. Marmo

We examine the dynamics of a free massless scalar field on a figure eight network. Upon requiring the scalar field to have a well defined value at the junction of the network, it is seen that the conserved currents of the theory satisfy Kirchhoff&#39;s law, that is that the current flowing into the junction equals the current flowing out. We obtain the corre

Erik Aurell, Per Salomonson

The functional determinant of an elliptic operator with positive, discrete spectrum may be defined as $e^{-Z&#39;(0)}$, where $Z(s)$, the zeta function, is the sum $\sum_n^{\infty} λ_n^{-s}$ analytically continued to $s$ around the origin. In this paper $Z&#39;(0)$ is calculated for the Laplace operator with Dirichlet boundary conditions inside polygons and

Toshio Nakatsu, Yuji Sugawara

A class of two-dimensional topological conformal field theories (TCFTs) is studied within the framework of gauged WZW models in order to gain some insights on the global geometrical nature of TCFTs. The BRST quantizations of topological G/H gauged WZW models (the twisted versions of SUSY gauged WZW models) are given under fixed back-ground gauge fields. The

T. Appelquist, G. Wu

A revised and complete list of the electroweak chiral lagrangian operators up to dimension-four is provided. The connection of these operators to the $S$, $T$ and $U$ parameters and the parameters describing the triple gauge boson vertices $WWγ$ and $WWZ$ is made, and the size of these parameters from new heavy physics is estimated using a one flavor-doublet

U. Baur, S. Errede, J. Ohnemus

The ratios ${\cal R}_{γ,\ell}=B(Z\to\ell^+\ell^-)\cdotσ(Zγ) /\allowbreak B(W\to\ellν)\cdotσ(W^\pmγ)$, ${\cal R}_{γ, ν}= B(Z\to\barνν)\cdotσ(Zγ)/\allowbreak B(W\to\ellν)\cdotσ(W^ \pmγ)$, ${\cal R}_{Wγ}=σ(W^\pmγ)/\allowbreakσ(W^\pm)$, and ${\cal R}_{Zγ}=σ(Zγ)/\allowbreakσ(Z)$ are studied as tools to probe the electroweak boson self-interactions. As a function

Haim Goldberg, Rogerio Rosenfeld

We compute the approximate cross section $σ_n^{(0)}$ for producing $n-2$ {\it resolved} gluons in a gluon-gluon collision, using the Parke-Taylor formula regularized in a Lorentz invariant manner. We find, in double leading logarithm approximation, that \[ σ_{n}^{(0)} \approx \frac{1}{s} \left( \frac{N_cα_s}{2 π\sqrt{12}} \ \ln^{2} (s/s_{cut})\right)^{n-2}\

Thomas J. Weiler, K. Ghafoori--Tabrizi

The meaning and the extraction of heavy quark masses are discussed. A simple production model is presented which incorporates the running of the heavy quark mass into perturbative calculations. The model offers the possibilities of (i) understanding the differing charmed mass values extracted from different experiments, (ii) determining the short--distance m

Thomas M. Gould, I. Z. Rothstein

Standard decoupling of heavy fermions may fail when there are non-perturbative variations in a scalar field which gives masses to the fermions. One situation of phenomenological relevance is the case of sphalerons in the presence of fermions at finite temperatures. The free energy of a simple model is determined using a non-perturbative technique to study th

J. Lopez, D. Nanopoulos, X. Wang, A. Zichichi

Sparticle production and detection at HERA are studied within the recently proposed no-scale flipped $SU(5)$ supergravity model. Among the various reaction channels that could lead to sparticle production at HERA, only the following are within its limit of sensitivity in this model: $e^-p\to \tilde e^-_{L,R}χ^0_i+X, \tilde ν_eχ^-_1+X$, where $χ^0_i(i=1,2)$ a

M. Gleiser, G. C. Marques, R. O. Ramos

We examine the computation of the nucleation barrier used in the expression for false vacuum decay rates in finite temperature field theory. By a detailed analysis of the determinantal prefactor, we show that the correct bounce solution used in the computation of the nucleation barrier should not include loop corrections coming from the scalar field undergoi

Silas R. Beane, Samir Varma

By employing the dictum that axiomatic principles are devoid of predictive power, we find that the elastic unitarity constraint, applied to strong W$_L$W$_L$ scattering, does not alter the assumed spectrum of intermediate states. We consider intermediate states involving a heavy Higgs and heavy fermions of a hypothetical fourth generation doublet. In contras

J. Levelt, P. J. Mulders

We investigate one-particle semi-inclusive processes in lepton-hadron scattering. In unpolarized scattering order $Q^{-1}$ corrections appear only when transverse momenta are detected. We consider the twist two and three matrix elements and calculate the semi-inclusive structure functions in terms of quark correlation functions. We find that at twist three l

M. Genovese, D. B. Lichtemberg, E. Predazzi

We discuss the phenomenology of scalar and pseudoscalar mesons, emphasizing those which do not carry manifest flavor quantum numbers. Many of the properties of these mesons are still not fully understood. Some of them probably do not have the usual two-quark (quark-antiquark) structure, but may be mixed with glueball states or other exotics. %, hybrids, or f

C. Arzt

Effective Lagrangians, including those that are spontaneously broken, contain redundant terms. It is shown that the classical equations of motion may be used to simplify the effective Lagrangian, even when quantum loops are to be considered.

Thomas Kalkreuter

An idealized multigrid algorithm for the computation of propagators of staggered fermions is investigated. Exemplified in four-dimensional $SU(2)$ gauge fields, it is shown that the idealized algorithm preserves criticality under coarsening. The same is not true when the coarse grid operator is defined by the Galerkin prescription. Relaxation times in comput

Karel Kuchar

This is a review of the aspirations and disappointments of the canonical quantization of geometry. I compare the two chief ways of looking at canonical gravity, geometrodynamics and connection dynamics. I capture as much of the classical theory as I can by pictorial visualization. Algebraic aspects dominate my description of the quantization program. I addre

D. H. Coule, D. Solomons

We find the quantum analogues of Carlini-Mijic wormholes and consider their application to the cosmological constant problem. In a simple model with $Λ$ only we differ with the results of Strominger.

Viqar Husain

A four dimensional generally covariant field theory is presented which describes non-dynamical three geometries coupled to scalar fields. The theory has an infinite number of physical observables (or constants of the motion) which are constructed from loops made from scalar field configurations. The Poisson algebra of these observables is closed and is the s

Lizeng Zhang, Xiao-Qian Wang

The critical phenomenon of the zero temperature superfluid--Bose-glass phase transition for hard-core bosons on a three-dimensional disordered lattice is studied using a quantum real-space renormalization-group method. The correlation-length exponent $ν$ and the dynamic exponent z are computed. The critical exponent z is found to be 2.5 for compressible stat

Lizeng Zhang

A hard-core disordered boson system is mapped onto a quantum spin 1/2 XY-model with transverse random fields. It is then generalized to a system of spins with an arbitrary magnitude S and studied through a 1/S expansion. The first order 1/S expansion corresponds to a spin-wave theory. The effect of weak disorder is studied perturbatively within such a first

E. H. Lieb, M. Loss, R. J. McCann

A general class of hopping models on a finite bipartite lattice is considered, including the Hubbard model and the Falicov-Kimball model. For the half-filled band, the single-particle density matrix $\uprho (x,y)$ in the ground state and in the canonical and grand canonical ensembles is shown to be constant on the diagonal $x=y$, and to vanish if $x \not=y$

A. H. Castro Neto, Eduardo Fradkin

We bosonize the low energy excitations of Fermi Liquids in any number of dimensions in the limit of long wavelengths. The bosons are coherent superposition of electron-hole pairs and are related with the displacement of the Fermi Surface in some arbitrary direction. A coherent-state path integral for the bosonized theory is derived and it is shown to represe

Eric Yang, A. H. MacDonald

We report on a study of interaction effects in the tunneling density-of-states of a disordered two-dimensional electron gas in the strong magnetic field limit where only the lowest Landau level is occupied. Interactions in the presence of disorder are accounted for by performing finite-size self-consistent Hartree-Fock calculations. We find evidence for the

Shiping Feng, J. B. Wu, Z. B. Su, L. Yu

The electron momentum distribution function in the $t-J$ model is studied in the framework of slave particle approach. Within the decoupling scheme used in the gauge field and related theories, we treat formally phase and amplitude fluctuations as well as constraints without further approximations. Our result indicates that the electron Fermi surface observe

A. Biviano, M. Girardi, G. Giuricin, F. Mardirossian

We present the distribution of virial masses for nearby galaxy clusters, as obtained from a data-set of 75 clusters, each having at least 20 galaxy members with measured redshifts within 1 Abell radius. After having accounted for problems of incompleteness of the data-set, we fitted a power-law to the cluster mass distribution.

S. B. Giddings

One possible fate of information lost to black holes is its preservation in black hole remnants. It is argued that a type of effective field theory describes such remnants (generically referred to as informons). The general structure of such a theory is investigated and the infinite pair production problem is revisited. A toy model for remnants clarifies som

R. Manka, I. Bednarek, D. Karczewska

It is suggested that the nonorthodox model of a quasar as a neutrino ball described in terms of the standard model extended by adding right-handed neutrinos and the Majorana scalar field can be presented in order to explain a quasar as a body of weak interacting neutrinos. Neutrino interaction with the scalar Majorana field violates the lepton number and pro

Edward Witten

The conjecture that $N=2$ minimal models in two dimensions are critical points of a super-renormalizable Landau-Ginzburg model can be tested by computing the path integral of the Landau-Ginzburg model with certain twisted boundary conditions. This leads to simple expressions for certain characters of the $N=2$ models which can be verified at least at low lev

M. Alimohammadi, F. Ardalan, H. Arfaei

We consider the gauging of $ SL(2,R) $ WZNW model by its nilpotent subgroup E(1). The resulting space-time of the corresponding sigma model is seen to collapse to a one dimensional field theory of Liouville. Gauging the diagonal subgroup $ E(1) \times U(1) $ of $SL(2,R) \times U(1)$ theory yields an extremal three dimensional black string. We show that these

R. A. Sharipov

Newtonian dynamical systems accepting the normal shift on an arbitrary Riemannian manifold are considered. Partial differential equations forming the weak and additional normality conditions for them are reported.