October 1997 arXiv papers — page 13

S. J. Brodsky

I review progress made in solving gauge theories such as collinear quantum chromodynamics using light-cone Hamiltonian methods. I also show how the light-cone Fock expansion for hadron wavefunctions can be used to compute operator matrix elements such as decay amplitudes, form factors, distribution amplitudes, and structure functions, and how it provides a t

R. G. Edwards, U. M. Heller, T. R. Klassen

After describing the Schrödinger functional for standard and improved gluon and quark actions we present results for the non-perturbative clover coefficients of the SW quark action coupled to the Wilson plaquette action for $β\geq 5.7$, as well as the Lüscher-Weisz one-loop tadpole improved gauge action, both in the quenched approximation.

B. Alles, H. Panagopoulos, C. Parrinello, C. Pittori

We demonstrate the feasibility of computing alpha_s from the lattice three-gluon vertex in the Landau gauge. Data from 16^4 and 24^4 quenched lattices at beta=6.0 are presented. Our main result is that 2-loop asymptotic scaling is observed for momenta in the range 1.8-2.3 Gev, where lattice artifacts appear to be under control.

M. Goeckeler, R. Horsley, H. Oelrich, H. Perlt

We have technically improved the non-perturbative renormalization method, proposed by Martinelli et al., by using quark momentum sources and sinks. Composite two-fermion operators up to three derivatives have been measured for Wilson fermions and Sheikholeslami-Wohlert improved fermions in the quenched approximation. The calculations are performed in the Lan

T. Blum, A. Soni Brookhaven National Lab

Using domain wall fermions, we estimate $B_K(μ\approx 2 GeV)=0.628(47)$ in quenched QCD which is consistent with previous calculations. At $\gbeta=6.0$ and 5.85 we find the ratio $f_K/m_ρ$ in agreement with the experimental value, within errors. These results support expectations that $O(a)$ errors are exponentially suppressed in low energy ($E\ll a^{-1}$) o

Hideo Suganuma, Masahiro Fukushima, Hiroko Ichie, Atsunori Tanaka

The confinement mechanism in the nonperturbative QCD is studied in terms of topological excitation as QCD-monopoles and instantons. In the 't Hooft abelian gauge, QCD is reduced into an abelian gauge theory with monopoles, and the QCD vacuum can be regarded as the dual superconductor with monopole condensation, which leads to the dual Higgs mechanism. Th

V. A. Berezin, A. M. Boyarsky. A. Yu. Neronov

The quantum black hole model with a self-gravitating spherically symmetric thin dust shell as a source is considered. The shell Hamiltonian constraint is written and the corresponding Schroedinger equation is obtained. This equation appeared to be a finite differences equation. Its solutions are required to be analytic functions on the relevant Riemannian su

A. Mikovic, V. Radovanovic

We describe how the reduced phase space quantization of the CGHS model of 2d black hole formation allows one to calculate the backreaction up to any finite order in matter loops. We then analyze the backreaction in the Hawking radiation up to two loops. At one-loop order the Hawking temperature does not change, while at two-loop order the temperature increas

Cristian F. Moukarzel, Phillip M. Duxbury, Paul L. Leath

Tree models for rigidity percolation are introduced and solved. A probability vector describes the propagation of rigidity outward from a rigid border. All components of this ``vector order parameter'' are singular at the same rigidity threshold, $p_c$. The infinite-cluster probability $P_{\infty}$ is usually first-order at $p_c$, but often behaves a

Enzo Marinari, Giorgio Parisi, Federico Ricci-Tersenghi, Juan J. Ruiz-Lorenzo

We study the violation of the fluctuation-dissipation theorem in the three and four dimensional Gaussian Ising spin glasses using on and off equilibrium simulations. We have characterized numerically the function X(C) that determine the violation and we have studied its scaling properties. Moreover we have computed the function x(C) which characterize the br

Gongwen Peng, Takao Ohta

We study a two-dimensional granular system where external driving force is applied to each particle in the system in such a way that the system is driven into a steady state by balancing the energy input and the dissipation due to inelastic collision between particles. The velocities of the particles in the steady state satisfy the Maxwellian distribution. W

Giulio Casati, Giulio Maspero, Dima L. Shepelyansky

We study quantum chaos in open dynamical systems and show that it is characterized by quantum fractal eigenstates located on the underlying classical strange repeller. The states with longest life times typically reveal a scars structure on the classical fractal set.

Wolfhard Janke, Tilman Sauer

We investigate the properties of two standard energy estimators used in path-integral Monte Carlo simulations. By disentangling the variance of the estimators and their autocorrelation times we analyse the dependence of the performance on the update algorithm and present a detailed comparison of refined update schemes such as multigrid and staging techniques

R. Combescot

For a completely general anisotropic order parameter (including changes of sign), we show that weak coupling theory is incompatible with high values of the maximum Δ_{M} of the zero temperature gap as compared to the critical temperature T_{c}, such as those found experimentally in Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} where 2 Δ_{M} / T_{c} \approx 7.5 . This gives ev

S. Brehmer, A. K. Kolezhuk, H. -J. Mikeska, U. Neugebauer

We use the variational matrix-product ansatz to study elementary excitations in the S=1/2 ladder with additional diagonal coupling, equivalent to a single S=1/2 chain with alternating exchange and next-nearest neighbor interaction. In absence of alternation the elementary excitation consists of two free S=1/2 particles ("spinons") which are solitons

B. Huepper, B. Eckhardt

Semiclassical expansions for traces involving Greens functions have two contributions, one from the periodic or recurrent orbits of the classical system and one from the phase space volume, i.e. the paths of infinitesimal length. Quantitative calculations require the control of both terms. Here, we discuss the contribution from paths of zero length with an e

David P. Bennett

Zaritsky and Lin have recently suggested that the color magnitude diagram of the Large Magellanic Cloud (LMC) contains evidence of foreground red clump stars. They interpret this as evidence of tidal debris or a dwarf galaxy at a distance of $\sim 35$ kpc which may be responsible for the large gravitational microlensing optical depth observed by the MACHO Co

Andrei V. Gruzinov

Radiative efficiency of a slowly accreting black hole is estimated using a two-temperature model of accretion. The radiative efficiency depends on the magnetic field strength near the Schwarzschild radius. For weak magnetic fields (magnetic energy=equipartition/1000), the low efficiency 0.0001 assumed in some theoretical models might be achieved. For stronge

T. Appourchaux, M. C. Rabello-Soares, L. Gizon

In Part I we have developed a theory for fitting p-mode Fourier spectra assuming that these spectra have a multi-normal distribution. We showed, using Monte-Carlo simulations, how one can obtain p-mode parameters using 'Maximum Likelihood Estimators'. In this article, hereafter Part II, we show how to use the theory developed in Part I for fitting re

M. Le Louarn, R. Foy, N. Hubin, M. Tallon

We have constructed an analytical model to simulate the behavior of an adaptive optics system coupled with a sodium laser guide star. The code is applied to a 3.6-m and 8m class telescopes. The results are given in terms of Strehl ratio and full width at half maximum of the point spread function. Two atmospheric models are used, one representing good atmosph

Ortwin Gerhard, Gunther Jeske, R. P. Saglia, Ralf Bender

(abridged) We have measured line-of-sight velocity profiles (VPs) in the E0 galaxy NGC 6703 out to 2.6 R_e. From these data we constrain the mass distribution and the anisotropy of the stellar orbits in this galaxy. We have developed a non-parametric technique to determine the DF f(E,L^2) directly from the kinematic data. From Monte Carlo tests using the spa

Patrick Valageas, Richard Schaeffer

We calculate the multiplicity function of matter condensations by directly considering the actual, deeply non-linear density field, which we compare to the popular Press-Schechter approximation. We show the mass function is a function of a unique parameter that contains all the dependence on the mass and radius of the object. It enables us to derive the mass

Eliot Quataert

Recent work on Alfvenic turbulence by Goldreich & Sridhar (1995; GS) suggests that the energy cascades almost entirely perpendicular to the local magnetic field. As a result, the cyclotron resonance is unimportant in dissipating the turbulent energy. Motivated by the GS cascade, we calculate the linear collisionless dissipation of Alfven waves with frequenci

V. Berezinsky

Solar neutrinos are discussed in the light of the new data and of recent progress in helioseismology. Most attention is given to the new status of Standard Solar Models due to seismically measured density and sound speed in the inner solar core. The elementary particle solutions to the Solar Neutrino Problem and their observational signatures are discussed.

Gerard Lemson, Guinevere Kauffmann

We use large N-body simulations of dissipationless gravitational clustering in cold dark matter (CDM) cosmologies to study whether the properties of dark matter halos are affected by their environment. We look for correlations between the masses, formation redshifts, concentrations, shapes and spins of halos and the overdensity of their local environment. We

I. V. Moskalenko, A. W. Strong

We have made a new calculation of the cosmic-ray secondary positron spectrum using a diffusive halo model for Galactic cosmic-ray propagation. The code computes self-consistently the spectra of primary and secondary nucleons, primary electrons, and secondary positrons and electrons. The models are first adjusted to agree with the observed cosmic-ray Boron/Ca

P. M. Garnavich, R. P. Kirshner, P. Challis, J. Tonry

We have coordinated Hubble Space Telescope photometry with ground-based discovery for three supernovae: two SN Ia near z~0.5 (SN 1997ce, SN 1997cj) and a third event at z=0.97 (SN 1997ck). The superb spatial resolution of HST separates each supernova from its host galaxy and leads to good precision in the light curves. The HST data combined with ground-based

S. A. Levshakov, W. H. Kegel, F. Takahara

A new method, based on a Reverse Monte Carlo technique and aimed at the inverse problem in the analysis of interstellar (intergalactic) absorption lines is presented. We consider the process of line formation in media with a stochastic velocity field accounting for the effects of a finite correlation length (mesoturbulence). This approach generalizes the sta

B. C. Rubin, B. A. Haron, W. S. Paciesas, C. R. Robinson

The flux and spectrum of the black hole candidate GX339-4 has been monitored by the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-ray Observatory (CGRO) since the observatory became operational in May 1991. Between the summer of 1991 and the fall of 1996, eight outbursts from GX339-4 were observed. The history of these outbursts is one o

Paul L. Schechter, Michael D. Gregg, Robert H. Becker, David J. Helfand

The V=16.9 quasar FBQ 0951+2635 at redshift z=1.24 appears double on CCD exposures taken in subarcsecond seeing. The two objects are separated by 1.1" and differ in brightness by 0.9 mag. VLA observations show the radio source to be double with the same separation and position angle. Spectra taken with the Keck II telescope show the two components to hav

Gerard van der Geer, Marcel van der Vlugt

The weight hierarchy of generalized Reed-Muller codes over arbitrary finite fields was determined by Heijnen and Pellikaan. In this paper we produce curves over finite fields with many points which are closely related to this weight hierarchy.

Christophe Fraser, David Tong

We calculate instanton corrections to three dimensional gauge theories with N=4 and N=8 supersymmetry and SU(n) gauge groups. The N=4 results give new information about the moduli space of n BPS SU(2) monopoles, including the leading order non-pairwise interaction terms. A few comments are made on the relationship of the N=8 results to membrane scattering in

Carsten Gundlach

Choptuik has demonstrated that naked singularities can arise in gravitational collapse from smooth, asymptotically flat initial data, and that such data have codimension one in spherical symmetry. Here we show, for perfect fluid matter with equation of state $p=\rho/3$, by perturbing around spherical symmetry, that such data have in fact codimension one in t

Hugo Martel, Paul R. Shapiro

We present a set of cosmological variables, called "supercomoving variables," which are particularly useful for describing the gas dynamics of cosmic structure formation. For ideal gas with gamma=5/3, the supercomoving position, velocity, density, temperature, and pressure are constant in time in a uniform, isotropic, adiabatically expanding universe

I. H. Dwivedi

General relativistic spherically symmetric matter field with a vanishing stress energy scalar is analyzed. Procedure for generating exact solutions of the field equations for such matter distributions is given. It is further pointed out that all such type I spherically symmetric fields with distinct eignvalues in the radial two space can be treated as a mixt

G. Bonsignori, D. Vretenar, S. Cacciamani, L. Corradini

The Interacting Boson plus broken-pairs Model has been used to describe high-spin bands in spherical and transitional nuclei. In the spherical nucleus $^{104}$Cd the model reproduces the structure of high-spin bands built on a vibrational structure. Model calculations performed with a single set of parameters reproduce ten bands in $^{136}$Nd, including the

O. K. Kalashnikov

The one-loop dispersion equation which defines the collective excitations of the massive Dirac particles in hot and dense quark-gluon medium is obtained in the high temperature limit for the case $m<<T$ and solved explicitly for all $|\q|$ when $μ=0$. Four well-separated spectrum branches (quasi-particle and quasi-hole excitations) are found and their behavi

JLQCD Collaboration, S. Aoki, M. Fukugita, S. Hashimoto

We report on a study of two-flavor finite-temperature chiral phase transition employing the Kogut-Susskind quark action and the plaquette gluon action in lattice QCD for a lattice with $N_t=4$ temporal size. Hybrid R simulations of $10^4$ trajectories are made at quark masses of $m_q=0.075, 0.0375, 0.02, 0.01$ in lattice units for the spatial sizes $8^3, 12^

A. Hoferichter, V. K. Mitrjushkin, M. Müller-Preussker, H. Stüben

By comparison of the quenched and full formulations of compact QED with Wilson fermions we single out the effects of dynamical fermions on the `chiral transition line&#39; within the confinement phase. It is shown that this line cannot correspond to the chiral limit of the theory for all values of the gauge coupling. This seems to imply the existence of tri-

A. Hoferichter, E. Laermann, V. K. Mitrjushkin, M. Müller-Preussker

In quenched lattice QCD with standard Wilson fermions the quark propagator is computed very close to the chiral limit in the zero-temperature case. Starting from our experience with lattice QED we employ a modified statistical method in order to estimate reliably hadron masses.

JLQCD Collaboration, S. Aoki, M. Fukugita, S. Hashimoto

A summary is presented of a scaling study of the finite-temperature chiral phase transition of two-flavor QCD with the Kogut-Susskind quark action based on simulations on $L^3\times4$ ($L$=8, 12 and 16) lattices at the quark mass of $m_q=0.075, 0.0375, 0.02$ and 0.01. We find a phase transition to be absent for $m_q\geq 0.02$, and also quite likely at $m_q=0

Paul M. N. Feehan, Thomas G. Leness

This research announcement gives a brief report of the main results in our paper &#34;PU(2) monopoles, I: Regularity, Uhlenbeck compactness, and transversality&#34; (Journal of Differential Geometry, to appear). We describe the existence of perturbations for the PU(2) monopole equations, yielding both useful transversality properties and an Uhlenbeck compact

Jiri Malek, Konstantin Kladko, Sergej Flach

The ground state energies of infinite half-filled Hubbard-Peierls chains are investigated combining incremental expansion with exact diagonalization of finite chain segments. The ground state energy of equidistant infinite Hubbard (Heisenberg) chains is calculated with a relative error of less than $3 \cdot 10^{-3}$ for all values of $U$ using diagonalizatio

M. Y. Simmons, A. R. Hamilton, T. G. Griffiths, A. K. Savchenko

We have observed a metal-insulator transition in an ultra-low density two dimensional hole gas formed in a high quality GaAs-AlGaAs heterostructure at B=0. At the highest carrier density studied ($p_{s}=2.2x10^{10} cm^{-2}, r_{s}=16$) the hole gas is strongly metallic, with an exceptional mobility of $425,000 cm^{2}V^{-1}s^{-1}$. The low disorder and strengt

David H. Cobden, Marc Bockrath, Nasreen Chopra, Alex Zettl

We have performed transport spectroscopy on individual ropes of single-walled carbon nanotubes. We find that the levels are Zeeman split in a magnetic field, with a g-factor of 2.04 +- 0.05. The observed pattern of peak splittings indicates the parity of the number of electrons on the dot. In one device there are also signs of the presence of a second dot. W

R. J. Protheroe, C. L. Bhat, P. Fleury, E. Lorenz

During remarkable flaring activity in 1997 Markarian 501 was the brightest source in the sky at TeV energies, outshining the Crab Nebula by a factor of up to 10. Periods of flaring activity each lasting a few days were observed simultaneously by several gamma ray telescopes. Contemporaneous multiwavelength observations in April 1997 show that a substantial f

Zvezdelina E. Stankova-Frenkel

We study the moduli of trigonal curves. We establish the exact upper bound of ${36(g+1)}/(5g+1)$ for the slope of trigonal fibrations. Here, the slope of any fibration $X\to B$ of stable curves with smooth general member is the ratio $δ_B/λ_B$ of the restrictions of the boundary class $δ$ and the Hodge class $λ$ on the moduli space $\bar{\mathfrak{M}}_g$ to

Franz-Josef Elmer

The train model which is a variant of the Burridge-Knopoff earthquake model is investigated for a velocity-strengthening friction law. It shows self-organized criticality with complex scaling exponents. That is, the probability density function of the avalanche strength is a power law times a log-periodic function. Exact results (scaling exponent: $3/2+2πi/\

Matthew C. Strain, Henry S. Greenside

The spatiotemporal dynamics of an excitable medium with multiple spiral defects is shown to vary smoothly with system size from short-lived transients for small systems to extensive chaos for large systems. A comparison of the Lyapunov dimension density with the average spiral defect density suggests an average dimension per spiral defect varying between thr

Sangmin Lee, Amanda Peet, Larus Thorlacius

Recently, solutions of the Born-Infeld theory representing strings emanating from a Dirichlet p-brane have been constructed. We discuss the embedding of these Born-Infeld solutions into the non-abelian theory appropriate to multiple overlapping p-branes. We also prove supersymmetry of the solutions explicitly in the full nonlinear theory. We then study trans

Wade Smith, Kevin L. Haglin

Phi meson-baryon cross sections, estimated within a one-boson-exchange model, serve as input for a calculation of the collision rates in hot hadronic matter. We find that the width of the ϕmeson is modified through collisions with baryons by 1-10 MeV at 160 MeV temperature depending on the baryon fugacity. Thermalization of the ϕin high energy heavy ion coll

A. V. Afanasjev, G. A. Lalazissis, P. Ring

The cranked relativistic mean field theory is applied for a detailed investigation of eight superdeformed rotational bands observed in $^{151}$Tb. It is shown that this theory is able to reproduce reasonably well not only the dynamic moments of inertia $J^{(2)}$ of the observed bands but also the alignment properties of the single-particle orbitals.

A. V. Afanasjev, I. Ragnarsson

The relative properties of smooth terminating bands observed in the A~110 mass region are studied within the effective alignment approach. Theoretical values of $i_{eff}$ are calculated using the configuration-dependent shell-correction model with the cranked Nilsson potential. Reasonable agreement with experiment shows that previous interpretations of these

A. V. Afanasjev, I. Ragnarsson

The properties of rotational bands at the limit of angular momentum are discussed on the example of smooth terminating bands observed in the A~110 mass region. The effective alignment approach is used for the study of their relative properties which provides additional insight into the properties of such bands.

Teiji Kunihiro

On the basis of the NJL model as an effective theory of QCD and analogies with condensed matter physics, we extract simple physical pictures of the chiral phase transition at finite temperature $T$ and/or chemical potential $μ$ and predict interesting phenomena associated with the phase transition which may be seen in relativistic heavy-ion collisions to be

J. I. Skullerud

We present results for the QCD running coupling obtained from measuring the quark-gluon vertex in Landau gauge with suitable renormalisation conditions. The issue of discretisation errors arising from the fermion action is discussed.

The OPAL Collaboration, K. Ackerstaff et al

Events containing a pair of charged leptons and significant missing transverse momentum are selected from a data sample corresponding to a total integrated luminosity of 20.6 pb^-1 at centre-of-mass energies of 161 GeV and 172 GeV. The observed number of events, four at 161 GeV and nine at 172 GeV, is consistent with the number expected from Standard Model p

Santiago E. Perez Bergliaffa, Gustavo E. Romero, Hector Vucetich

We present a deductive theory of space-time which is realistic, objective, and relational. It is realistic because it assumes the existence of physical things endowed with concrete properties. It is objective because it can be formulated without any reference to cognoscent subjects or sensorial fields. Finally, it is relational because it assumes that space-

László Á. Gergely, Zoltán I. Perjés, Mátyás Vasúth

The gravitational radiation backreaction effects are considered in the Lense-Thirring approximation. New methods for parameterizing the orbit and for averaging the instantaneous radiative losses are developed. To first order in the spin S of the black hole, both in the absence and in the presence of gravitational radiation, a complete description of the test

R. R. P. Singh, O. A. Starykh, P. J. Freitas

Motivated by the geometry of the materials Na_2 Ti_2 As_2 O and Na_2 Ti_2 Sb_2 O, we study a square-lattice Heisenberg antiferromagnet with spins located at the bond-centers. The largest exchange constant J couples neighboring spins in a given row or column. This leads to a mesh of isolated spin-chains running along the X and Y axes. A weaker exchange consta

D. N. Sheng, Z. Y. Weng

A new universality of metal-insulator transition in integer quantum Hall effect (IQHE) system is studied based on a lattice model, where the IQHE states only exist within a finite range of Fermi energy in the presence of disorders. A two-parameter scaling law is found at the high-energy boundary where direct transitions from high IQHE states to insulator occ

Takeshi Nakanishi, Tomi Ohtsuki

Diffusion of electrons in a two-dimensional system with time-dependent random potentials is investigated numerically. In the absence of spin-orbit scattering, the conductivity shows universal weak localization correction. In the presence of it, however, the correction to the conductivity weakly depends on the strength of disorder, and becomes vanishingly sma

Hiroshi Tsukahara, Takeo Inami

We investigate the analyticity property of the partially resummed series expansion(PRSE) of the partition function for the eight-vertex model. Developing a graphical technique, we have obtained a first few terms of the PRSE and found that these terms have a pole only at one point in the complex plane of the coupling constant. This result supports the conject

S. Frankel, W. Frati

All measured Feynman x_f distributions of the ratio, R, of j_psi production in nuclei relative to production on protons fall off with x_f. They show [2] that absorption of charmonium cannot be the only source of j_psi suppression and that energy loss of the constituents of the incident proton prior to the j_psi production, because of the exponential sqrt(s)

M. Abou Zeid, C. M. Hull

A system of gravity coupled to a 2-form gauge field, a dilaton and Yang-Mills fields in $2n$ dimensions arises from the (2,1) sigma model or string. The field equations imply that the curvature with torsion and Yang-Mills field strength are self-dual in four dimensions, or satisfy generalised self-duality equations in $2n$ dimensions. The Born-Infeld-type ac

I. L. Drichko, A. M. Diakonov, I. Yu. Smirnov, A. V. Suslov

High-frequency (HF) conductivity ($σ_{hf}$) measured by an acoustical method has been studied in GaAs/AlGaAs heterostructures in a linear and nonlinear regime on acoustic power. It has been shown that in the quantum Hall regime at magnetic fields corresponding to the middle of the Hall plateaus the HF conductivity is determined by the sum of the conductivity

A. Dobado, M. J. Herrero, S. Peñaranda

The possibility of a heavy supersymmetric spectrum at the Minimal Supersymmetric Standard Model is considered and the decoupling from the low energy electroweak scale is analyzed in detail. The formal proof of decoupling of supersymmetric particles from low energy physics is stated in terms of the effective action for the particles of the Standard Model that

Hou Defu, U. Heinz

We derive the spectral representations of QED 3-point functions and then explicitly calculate the 3-point spectral densities in hard thermal loop approximation within the real time formalism. The Ward identities obeyed by the retarded and advanced 2- and 3-point functions are discussed. We compare our results with those for hot QCD .

P. Ciafaloni, A. Romanino, A. Strumia

The charged-Higgs-mediated contribution to the Wilson coefficient of the $b\to sγ$ magnetic penguin is expected to be one of the more promising candidates for a supersymmetric effect in B physics, probably the only one in gauge-mediated models. We compute the two-loop QCD correction to it. With naive dimensional regularization and MSbar subtraction, for reas

Teiji Kunihiro

The renormalization group method is applied for obtaining the asymptotic form of the wave function of the quantum anharmonic oscillator by resumming the perturbation series. It is shown that the resumed series is the cumulant of the naive perturbation series. Working out up to the sixth order and performing a further resummation proposed by Bender and Betten

Mehmet Dilaver, Paolo Rossi, Yigit Gunduc

Within the 1/N expansion of O(N) nonlinear $σ$ models for $d \leq 4$ it is possible to separate consistently the spin-wave and the massive-mode contributions to the scaling part of the free energy near criticality, and to evaluate them to $O(1/N)$. For critical dimensions $d = 2+2/n$ the Abe-Hikami anomaly is recovered, while for $d=2$ the removal of the spi

John W. Barrett, Martin Rocek, Ruth M. Williams

We consider the possibility of setting up a new version of Regge calculus in four dimensions with areas of triangles as the basic variables rather than the edge-lengths. The difficulties and restrictions of this approach are discussed.

Anton Andreev, Alex Kamenev

We address the problem of infrared singularities in the perturbation theory for disordered interacting systems in $d\leq 2$. We show that a typical, sufficiently large interacting system exhibits a linear instability in the spin triplet channel. In a density-density channel, although stability is preserved, a large number of soft modes is accumulated. These

Harold Steinacker

It is shown that for suitable roots of unity, there exist finite--dimensional unitary representations of $U_q(so(2,3))$ corresponding to all classical one-particle representations with (half)integer spin, with the correct low-energy limit. In the massless case for spin $\geq 1$, a subspace of &#34;pure gauges&#39;&#39; appears which must be factored out, as

A. Frank, R. Lemus, R. Bijker, F. Perez-Bernal

An algebraic method especially suited to describe strongly anharmonic vibrational spectra in molecules may be an appropriate framework to study vibrational spectra of Na$^+_n$ clusters, where nearly flat potential energy surfaces and the appearance of close lying isomers have been reported. As an illustration we describe the model and apply it to the Be$_4$,

Urban Weber, Judith A. McGovern

We propose a self-consistant approach to the treatment of nuclear matter as a crystal of solitons in the Wigner-Seitz approximation. Specifically, we use a Bloch-like boundary condition on the quarks at the edge of a spherical cell which allows the dispersion relation for a given radius to be calculated self-consistently along with the meson fields; in previ

Olivier Piguet

In these lectures I present a basic introduction to supersymmetry, especially to N=1 supersymmetric gauge theories and their renormalization, in the Wess-Zumino gauge. I also discuss the various ways supersymmetry may be broken in order to account for the lack of exact supersymmetry in the actual world of elementary particles.

Detlev Buchholz

Within the framework of algebraic quantum field theory a general method is presented which allows one to compute and classify the short distance (scaling) limit of any algebra of local observables. The results can be used to determine the particle and symmetry content of a theory at very small scales and thereby give an intrinsic meaning to notions such as `

Andreas Aste, Michael D&#34;utsch, G&#34;unter Scharf

The gauge dependence of the time-ordered products for Yang-Mills theories is analysed in perturbation theory by means of the causal method of Epstein and Glaser together with perturbative gauge invariance. This approach allows a simple inductive proof of the gauge independence of the physical S-matrix.

Antonio Liguori, Mihail Mintchev

We develop a bosonization procedure on the half line. Different boundary conditions, formulated in terms of the vector and axial fermion currents, are implemented by using in general the mixed boundary condition on the bosonic field. The interplay between symmetries and boundary conditions is investigated in this context, with a particular emphasis on dualit

C. D. Fosco, C. Núñez, F. A. Schaposnik

We study the functional integrals that appear in a path integral bosonization procedure for more than two spacetime dimensions. Since they are not in general exactly solvable, their evaluation by a suitable loop expansion would be a natural procedure, even if the exact fermionic determinant were known. The outcome of our study is that we can consistently ign

G. T. Ter-Kazarian

The question that guides our discussion is how did the geometry and particles come into being. The present theory reveals primordial deeper structures underlying fundamental concepts of contemporary physics. We begin with a drastic revision of a role of local internal symmetries in physical concept of curved geometry. A standard gauge principle of local inte

Jim McCarthy, Andy Wilkins

We examine the claim that the effective action of four-dimensional SU(2)_L gauge theory at high and low temperature contains a three-dimensional Chern-Simons term with coefficient being the chemical potential for baryon number. We perform calculations in a two-dimensional toy model and find that the existence of the term is rather subtle.

Sergei V. Ketov

The effective field equations of motion for a mixed theory of open and closed (2,2) world-sheet supersymmetric critical strings are shown to be integrable in the case of an abelian gauge group. The Born-Infeld-type effective action in 2+2 dimensions is intrinsically non-covariant, and it can be interpreted as (a part of) the F-brane world-volume action. The

I. Akushevich, A. Nagaitsev

The sources of the systematical uncertainties due to radiative correction procedure in measurements of the structure function $g_1^n$ with $^3$He target are considered. Their numerical estimations are presented. The relative systematical uncertainty does not exceed 5%.

Mark Trodden

I review recent work concerning the microphysics of cosmic string solutions of N=1 supersymmetric gauge field theories.

M. D. Scadron

We show that the non-strange scalar $σ$ meson, as now reported in the 1996 PDG tables, is a natural consequence of crossing symmetry as well as chiral dynamics for both strong interaction low energy $ππ$ scattering and also $K \to 2π$ weak decays.

Kimball A. Milton, Olga P. Solovtsova

The renormalization group applied to perturbation theory is ordinarily used to define the running coupling constant in the spacelike region. However, to describe processes with timelike momenta transfers, it is important to have a self-consistent determination of the running coupling constant in the timelike region. The technique called analytic perturbation

A. Halprin

I will discuss three related unconventional ways to generate neutrino oscillations (1)Equivalence principle violation by the string dilaton field (i2)Violation of Lorentz Invariance and (3) Equivalence principle violation through a non-universal tensor neutrino-gravity coupling. These unorthodox neutrino oscillation mechanisms are shown to be viable at the l

G. Dvali, G. Lazarides, Q. Shafi

We present a solution of the mu problem within a supersymmetric model based on the SU(2)_L x SU(2)_R x U(1)_{B-L} gauge group. We show that this solution implies a built-in hybrid inflationary scenario, which may result in a successful baryogenesis via leptogenesis. Baryon number is essentially conserved as a result of an R-symmetry. Neutrinos with mass in t

J. Rafelski, J. Letessier, A. Tounsi

Using renormalization group methods we evaluate the thermal strangeness and charm chemical equilibrium relaxation times in the deconfined quark-gluon plasma. We present a reaction model and evaluate the total production rate of strangeness in fixed target Pb-Pb collisions at 10--300 A GeV. We discuss the relevance of our results to the diagnosis and understa

Jean Letessier, Johann Rafelski, Ahmed Tounsi

We study relative strange particle abundances measured in Pb-Pb 158 A GeV interactions. The thermal and chemical source parameters of these particles are determined under reaction scenario hypothesis invoking confined and deconfined hadronic matter.

P. Q. Hung

The issue of gauge unification in the (non-supersymmetric) Standard Model is reinvestigated. It is found that with just an additional fourth generation of quarks and leptons, $SU(3) \otimes SU(2) \otimes U(1)$ gauge couplings converge to a common point $\sim 2.65 \times 10^{15}$ GeV ($τ_p \sim 10^{34 \pm 1}$ years) provided the Higgs boson has a mass of at l

Achim Bode

The two loop coefficient of the expansion of the Schroedinger functional coupling in terms of the lattice coupling is calculated for the SU(3) Yang-Mills theory. This coefficient is required to relate lattice data to the MS-bar-coupling. As a byproduct of the calculation, the Schroedinger functional is improved to two loop order and the three loop coefficien

M. Baig, J. Clua

We have studied the monopole-percolation phenomenon in the four dimensional Abelian theory that contains compact U(1) gauge fields coupled to unitary norm Higgs fields. We have determined the location of the percolation transition line in the plane $(β_g, β_H)$. This line overlaps the confined-Coulomb and the confined-Higgs phase transition lines, originated

Attilio Cucchieri, Tereza Mendes

We study the influence of Gribov copies on gluon and ghost propagators in lattice Landau gauge. For the gluon propagator, Gribov noise seems to be of the order of magnitude of the numerical accuracy. On the contrary, for the ghost propagator, Gribov noise is clearly observable, at least in the strong- coupling regime. We also observe, in the limit of large l

ALEPH Collaboration

Searches for supersymmetric particles in channels with one or more photons and missing energy have been performed with data collected by the ALEPH detector at LEP. The data consist of 11.1 pb-1 at $\sqrt{s} = 161 GeV$, 1.1 pb-1 at 170 GeV and 9.5 pb-1 at 172 GeV. The e+e- -> nunu+photon cross section is measured. The data are in good agreement with predictio

F. Abe

We present a measurement of the t-tbar cross section in p-pbar collisions at sqrt(s)=1.8 TeV using an integrated luminosity of 109 pb-1 collected with the Collider Detector at Fermilab. The measurement uses t-tbar decays into final states which contain one or two high transverse momentum leptons and multiple jets, and final states which contain only jets. Us

Reinoud J. Slagter

It is claimed that it will be exceedingly unlikely to obtain CTC&#39;s in the spacetime of a spinning EYMH-string. It is conjectured that the pathological problems concerning the induced angular momentum and helical structure of time that afflict the U(1)-gauge string, will be solved in the non-abelian YM string model. In the pure YM case we find regular sol

J. Hwang

We present a general and unified formulation which can handle the classical evolution and quantum generation processes of the cosmological gravitational wave in a broad class of generalized gravity theories. Applications are made in several inflation models based on the scalar-tensor theory, the induced gravity, and the low energy effective action of string