January 1996 arXiv papers — page 7

Andrei Linde

Typically the moduli fields acquire mass m =C H in the early universe, which shifts the position of the minimum of their effective potential and leads to an excessively large energy density of the oscillating moduli fields at the later stages of the evolution of the universe. This constitutes the cosmological moduli problem, or Polonyi field problem. We show

E. T. Tomboulis

We show the exact equality of the path integral of the general renormalizable fourth order gravitational action to the path integral of the Einstein action coupled to a massive spin-0 field and a massive spin-2 ghost-like field with non-polynomial interactions. The metric in the Einstein version is a highly nonlinear function of the metric in the quadratic v

F. Freire, C. Wetterich

The dependence of the effective action for gauge theories on the background field obeys an exact identity. We argue that for Abelian theories the Ward identity follows from the more general background field identity. This observation is particularly relevant for the anomalous Ward identity valid for gauge theories with an effective infrared cutoff as used fo

G. Eyal, M. Moshe, S. Nishigaki, J. Zinn-Justin

The multicritical points of the $O(N)$ invariant $N$ vector model in the large $N$ limit are reexamined. Of particular interest are the subtleties involved in the stability of the phase structure at critical dimensions. In the limit $N \to \infty$ while the coupling $g \to g_c$ in a correlated manner (the double scaling limit) a massless bound state $O(N)$ s

John Ellis, Marek Karliner

The recent series of experiments on polarized lepton-nucleon scattering have provided a strange new twist in the story of the nucleon, some of whose aspects are reviewed in these lectures. In the first lecture, we review some issues arising in the analysis of the data on polarized structure functions, focusing in particular on the importance and treatment of

J. Binnewies, B. A. Kniehl, G. Kramer

We study inclusive charged-hadron production in collisions of quasireal photons at NLO in perturbative QCD, using fragmentation functions recently extracted from PEP and LEP1 data. We superimpose the direct (DD), single-resolved (DR), and double-resolved (RR) gamma-gamma channels. First, we confront existing data taken by TASSO at PETRA and by MARK II at PEP

Matteo Cacciari, Michael Krämer

We have calculated the leading color-octet contributions to the production of $J/ψ$ particles in photon-proton collisions. Using the values for the color-octet matrix elements extracted from fits to prompt $J/ψ$ data at the Tevatron, we demonstrate that distinctive color-octet signatures should be visible in $J/ψ$ photoproduction. However, these predictions

Markus Finkemeier, Erwin Mirkes

We consider the scalar form factor in $τ\to Kπν_τ$ decays. It receives contributions both from the scalar resonance $K_0^*(1430)$ and from the scalar projection of off-shell vector resonances. We construct a model for the hadronic current which includes the vector resonances $K^*(892)$ and $K^*(1410)$ and the scalar resonance $K_0^*(1430)$. The parameters of

Daniele Dominici

The sensitivity of future $e^+e^-$ colliders to the new physics deriving from a model of strong electroweak symmetry breaking is discussed. The model considered is an effective lagrangian description of Goldstone bosons and of new vector resonances degenerate in mass.

Ilya F. Ginzburg

The main source of \epe pair at $μ^+μ^-$ collider is incoherent process $μ^+μ^-\to μ^+μ^-\epe$ with cross section about 10 mb (at muon energy 2 TeV). The corresponding distributions are discussed briefly. These pairs give the dangerous background. The coherent production of \epe pairs here is negligibly small.

Ilya F. Ginzburg

I consider the process $μ^+μ^-\to e\barνW^+$ in the case when the effective mass of the $(e\barν)$ system than the muon mass. In this case the momentum transferred from the initial muon to the $e\barν$ system (the virtual neutrino momentum) can be both time--like and space--like. Since the path of integration over $k^2$ goes through a pole at $k^2=0$, it giv

M. R. Ahmady, R. R. Mendel, J. D. Talman

We extend our recent work, in which the Dirac equation with a ``(asymptotically free) Coulomb + (Lorentz scalar $γ_0σr$) linear '' potential is used to obtain the light quark wavefunction for $q\bar Q$ mesons in the limit $m_Q\to \infty$, to estimate the decay constant $f_P$ and the mixing parameter $B$ of the pseudoscalar mesons. We compare our resu

M. Caselle

We review some analytic results on the deconfinement transition in pure lattice gauge theories. In particular we discuss the relationship between the deconfinement transition in the $(d+1)$-dimensional $SU(2)$ model and the magnetization transition in the $d$-dimensional Ising model. This analysis leads to a precise estimate of the deconfinement temperature

A. T. Doyle

Measurements of diffractive phenomena observed at HERA are reviewed. A short introduction to the theoretical background is presented. The review focuses on the current experimental directions and discusses the exclusive production of vector mesons, the deep inelastic structure of diffraction and complementary information from jet structures. Emphasis is plac

David L. Finn

The negative case of the Singular Yamabe Problem concerns the existence and behavior of complete metrics with constant negative scalar curvature on the complement of a closed set in a compact Riemannian manifold which are conformally equivalent to a smooth metric on this compact manifold. When the closed set is a smooth submanifold, it is known by the result

M. W. Wu, H. L. Cui, N. J. M. Horing

In this paper we clarify the role of heat flux in the hydrodynamic balance equations, facilitating the formulation of an Onsager relation within the framework of this theory. Previously thought to be unobtainable from the present form of the theory [X.L. Lei, J. Cai, and L.M. Xie, Phys. Rev. B {\bf 38},1529 (1988)], our verification of the Onsager relation f

S. Majaniemi, T. Ala--Nissila, J. Krug

We present a comprehensive analysis of a linear growth model, which combines the characteristic features of the Edwards--Wilkinson and noisy Mullins equations. This model can be derived from microscopics and it describes the relaxation and growth of surfaces under conditions where the nonlinearities can be neglected. We calculate in detail the surface width

Rolf R. Gerhardts, Daniela Pfannkuche, Vidar Gudmundsson

We calculate the energy spectrum of an electron moving in a two-dimensional lattice which is defined by an electric potential and an applied perpendicular magnetic field modulated by a periodic surface magnetization. The spatial direction of this magnetization introduces complex phases into the Fourier coefficients of the magnetic field. We investigate the e

Boris Narozhny

We study the problem of spin diffusion in magnetic systems without long-range order. We discuss the example of the 1D spin chain. For the system described by the Heisenberg Hamiltonian we show that there are no diffusive excitations. However, the addition of an arbitrarily small dissipation term, such as the spin-phonon interaction leads to diffusive excitat

Jeppe C. Dyre, Thomas B. Schroeder

It is argued that in the limit of extreme disorder AC hopping is dominated by "percolation paths". Modelling a percolation path as a one-dimensional path with a sharp jump rate cut-off leads to an expression for the universal AC conductivity, that fits computer simulations in two and three dimensions better than the effective medium approximation.

C. H. Booth, F. Bridges, J. B. Boyce, T. Claeson

We have performed fluorescence x-ray absorption fine-structure (XAFS) measurements from 20-200 K on a 5000 Å, c-axis film of YBa_2Cu_3O_{7-δ} (YBCO) on MgO (Tc=89 K) using photons polarized perpendicular to the film. These data are compared to YBCO data from a single crystal and from a film on LaAlO_3 with the same Tc. The main difference between the single

José Maria Fullana, Maurice Rossi, Stéphane Zaleski, Patrice Le Gal

We study the flow behind an array of equally spaced parallel cylinders. A system of Stuart-Landau equations with complex parameters is used to model the oscillating wakes. Our purpose is to identify the 6 scalar parameters which most accurately reproduce the experimental data of Chauve and Le Gal [{Physica D {\bf 58}}, pp 407--413, (1992)]. To do so, we perf

Vincent R. Eke, Shaun Cole, Carlos S. Frenk

The population of rich galaxy clusters evolves much more rapidly in a universe with critical density than one with low density, thus offering the possibility of determining the cosmological density parameter, Omega_0. We quantify this evolution using the Press-Schechter formalism which we extend to flat models with a cosmological constant. Using new large N-

Li-Zhi Fang, Zheng Huang, Xian-Ping Wu

Using the Boltzmann equation with a Langevin-like term describing the stochastic force in a baryon-photon plasma, we investigate the influence of the incoherent electron-photon scattering on the subhorizon evolution of the cosmic microwave radiation. The stochastic fluctuation caused by each collision on average is found to be small. Nevertheless, it leads t

Adriano Fontana, Stefano Cristiani, Sandro D'Odorico, Emanuele Giallongo

We have obtained with the SUSI CCD camera on the ESO 3.5m NTT deep images in the BVRI bands of the field centered on the QSO BRI 1202-0725 ($z_{\it em}=4.694$). In the final combined frames the stellar images have FWHM of 1,1,0.6 and 0.65 arcsec respectively. The R and I images show clearly a galaxy $2.2''$ from the QSO, corresponding to $13h^{-1}_{5

Wesley N. Colley, J. Richard Gott, III, Changbom Park

We have measured the topology (genus) of the fluctuations in the cosmic microwave background seen in the recently completed (four-year) data set produced by the COBE satellite. We find that the genus is consistent with that expected from a random-phase Gaussian distribution, as might be produced naturally in inflationary models.

Robert Treger

We describe degenerations of projective plane curves to curves containing a fixed line $l$ as a component, and show that $H^1({\overline V}_{n,d,m}, {\Cal O} (r))=0, r \in{\Bbb Z}$, where $V_{n,d,m}\subset {\Bbb P}^N (N = n(n+3)/2)$ is the subscheme consisting of irreducible plane curves having smooth contact of order at least m with $l$ at a fixed point p o

V. B. Belyaev, A. K. Motovilov, W. Sandhas

The probability of nuclear transitions $p+p+{}^{16}{O} \, \rightarrow \, {}^{18}{Ne}\, (4.522,1^-)$ in molecular water is estimated. Due to the practically exact agreement of the energy of the $Ne$ resonance and of the $p+p+{}^{16}{O}$ threshold, the transition probability is found to be considerably enhanced. This indicates the possibility of nuclear fusion

Maxim Sokolov

The Turaev-Viro invariant is defined as a certain state sum calculated on an arbitrary simple spine of a 3-manifold. We specify each term of the sum as 0-term, 1-term or 2-term such that each sum of the terms having the same type is an invariant too. The sum of the 0-terms is equal to the square of the modulus of the so-called SO(3)-invariant. In the paper w

Jiri Hoogland, Ronald Kleiss

We show how information on the uniformity properties of a point set employed in numerical multidimensional integration can be used to improve the error estimate over the usual Monte Carlo one. We introduce a new measure of (non-)uniformity for point sets, and derive explicit expressions for the various entities that enter in such an improved error estimate.

Daniel S. Freed

A recent anomaly computation of Horava and Witten is proved and generalized in the form of two index theorems in odd dimensions. Theorem A is a fixed point formula for orientation-reversing involutions. Theorem B is an index theorem for manifolds with boundary using local boundary conditions. Both hold for families of operators.

Riccardo Argurio

We find black hole solutions to Euclidean 2+1 gravity coupled to a relativistic particle which have a dynamical conical singularity at the horizon. These solutions mimic the tree level contribution to the partition function of gravity coupled to a quantum field theory. They are found to violate the standard area law for black hole entropy, their entropy bein

Murat Gunaydin, Sergei V. Ketov

We study realizations of the exceptional non-linear (quadratically generated, or W-type) N=8 and N=7 superconformal algebras with Spin(7) and G_2 affine symmetry currents, respectively. Both the N=8 and N=7 algebras admit unitary highest-weight representations in terms of a single boson and free fermions in 8 of Spin(7) and 7 of G_2, with the central charges

Max Tegmark

The angular power spectrum C_l is extracted from the 4 year COBE DMR data with a 20 degree galactic cut, using the narrowest window functions possible. The average power in eight multipole bands is also computed, and plotted together with a compilation of power spectrum measurements from other experiments. The COBE results are found to be consistent with an

Martin Daumer, Detlef Dürr, Sheldon Goldstein, Nino Zangh\`ı

A source of much difficulty and confusion in the interpretation of quantum mechanics is a ``naive realism about operators.'' By this we refer to various ways of taking too seriously the notion of operator-as-observable, and in particular to the all too casual talk about ``measuring operators'' that occurs when the subject is quantum mechanics

B. Carazza, Diparimento di Fisica, Parma

Position holds a very special role in understanding the classical behaviour of macroscopic bodies on the basis of quantum principles. This lead us to examine the localised states of a large condensed object in the context of a realistic model. Following the argument that an isolated macroscopic body is usually described by a linear superposition of low-lying

J. Leon, J. M. Martin

The kinematic degrees of freedom of spinning particles are analyzed and an explicit construction of the phase space and the simplectic structure that accomodates them is presented. A Poincare invariant theory of classical spinning particles that generalizes the work of Proca and Barut to arbitrary spin is given using spinor variables. Second quantization is

S. O. Warnaar

We prove polynomial boson-fermion identities for the generating function of the number of partitions of $n$ of the form $n=\sum_{j=1}^{L-1} j f_j$, with $f_1\leq i-1$, $f_{L-1} \leq i'-1$ and $f_j+f_{j+1}\leq k$. The bosonic side of the identities involves $q$-deformations of the coefficients of $x^a$ in the expansion of $(1+x+\cdots+ x^k)^L$. A combinat

T. Kido, K. Yabana, Y. Suzuki

The mechanism of the Coulomb breakup reactions of the nuclei with neutron-halo structure is investigated in detail. A time-dependent Schrödinger equation for the halo neutron is numerically solved by treating the Coulomb field of a target as an external field. The momentum distribution and the post-acceleration effect of the final fragments are discussed in

J. Bennetto, David Vanderbilt

We calculate the transverse effective charges of zincblende compound semiconductors using Harrison's tight-binding model to describe the electronic structure. Our results, which are essentially exact within the model, are found to be in much better agreement with experiment than previous perturbation-theory estimates. Efforts to improve the results by us

Mirna Džamonja, Saharon Shelah

Suppose that lambda is the successor of a singular cardinal mu whose cofinality is an uncountable cardinal kappa. We give a sufficient condition that the club filter of lambda concentrating on the points of cofinality kappa is not lambda^+-saturated. The condition is phrased in terms of a notion that we call weak reflection. We discuss various properties of

Saharon Shelah

Monk asks (problems 13, 15 in his list; pi is the algebraic density):&#39;&#39;For a Boolean algebra B, aleph_0 <= theta <= pi (B), does B have a subalgebra B&#39; with pi (B&#39;)= theta ?&#39;&#39; If theta is regular the answer is easily positive, we show that in general it may be negative, but for quite many singular cardinals - it is positive; the theor

Eduardo A. Prado

In this work we will show that the Teichmüller distance for all elements of a certain class of generalized polynomial-like maps (the class of off-critically hyperbolic generalized polynomial-like maps) is actually a distance, as in the case of real polynomials with connected Julia set, as studied by Sullivan. This class contains several important classes of

Philip Boyland, Christopher Golé

This paper surveys various results concerning stability for the dynamics of Lagrangian (or Hamiltonian) systems on compact manifolds. The main, positive results state, roughly, that if the configuration manifold carries a hyperbolic metric, \ie a metric of constant negative curvature, then the dynamics of the geodesic flow persists in the Euler-Lagrange flow

Philip Boyland, Christopher Golé

This paper gives two results that show that the dynamics of a time-periodic Lagrangian system on a hyperbolic manifold are at least as complicated as the geodesic flow of a hyperbolic metric. Given a hyperbolic geodesic in the Poincaré ball, Theorem A asserts that there are minimizers of the lift of the Lagrangian system that are a bounded distance away and

John H. Schwarz

T duality expresses the equivalence of a superstring theory compactified on a manifold K to another (possibly the same) superstring theory compactified on a dual manifold K&#39;. The volumes of K and K&#39; are inversely proportional. In this talk we consider two M theory generalizations of T duality: (i) M theory compactified on a torus is equivalent to typ

J. Barcelos-Neto, S. Rabello

We consider the Salam-Weinberg theory by introducing tensor gauge fields. When these fields are coupled in a topological way with the vector ones, the resulting system constitutes an alternative mechanism of mass generation for vector fields without the presence of Higgs bosons. We show that these masses are in agreement with the ones obtained by means of th

G W Gibbons

The point of this paper is see what light new results in hyperbolic geometry may throw on gravitational entropy and whether gravitational entropy is relevant for the quantum origin of the univeres. We introduce some new gravitational instantons which mediate the birth from nothing of closed universes containing wormholes and suggest that they may contribute

S. Corley, T. Jacobson

We study the spectrum of created particles in two-dimensional black hole geometries for a linear, hermitian scalar field satisfying a Lorentz non-invariant field equation with higher spatial derivative terms that are suppressed by powers of a fundamental momentum scale $k_0$. The preferred frame is the ``free-fall frame&#34; of the black hole. This model is

M. Mekhfi

We reconsider quantum mechanical systems based on the classical action being the period of a one form over a cycle and elucidate three main points. First we show that the prepotenial V is no longer completely arbitrary but obeys a consistency integral equation. That is the one form dV defines the same period as the classical action. We then apply this to the

Oscar J. P. Eboli, F. de Campos, J. Rosiek, J. W. F. Valle

We study the potential of LEP II to unravel the existence of invisibly decaying Higgs bosons, predicted in a wide class of models. We perform a model independent analysis, focusing our attention to the final state topologies exhibiting $b \bar{b}$ or $\ell^+ \ell^-$ ($\ell=μ$ or $e$) pairs and missing energy. We carefully evaluate the signals and backgrounds

T. S. Evans, D. A. Steer

We consider Wick&#39;s Theorem for finite temperature and finite volume systems. Working at an operator level with a path ordered approach, we show that contrary to claims in the literature, expectation values of normal ordered products can be chosen to be zero and that results obtained are independent of volume. Thus the path integral and operator approache

V. Bernard, N. Kaiser, Ulf-G. Meißner

We investigate neutral pion electroproduction off protons in the framework of heavy baryon chiral perturbation theory. The chiral expansion of the S--wave multipoles $E_{0+}$ and $L_{0+}$ is carried out to three orders. There appear several undetermined low--energy constants. Three are taken from a recent study of the new TAPS threshold $π^0$ photoproduction

S. M. Bilenky

The status of the problem of neutrino masses and mixing is shortly reviewed. Different schemes of mixing of (Dirac or Majorana) massive neutrinos are considered. The theory of neutrino oscillations in vacuum and in matter is presented. Existing indications in favor of neutrino mixing are shortly discussed.

Piotr Zenczykowski

Effects of final-state interactions in nonleptonic decays of charmed mesons are studied in the framework of quark-diagram approach. For the case of u-d-s flavour symmetry we discuss how the inelastic coupled-channel rescattering effects (and, in particular, resonance formation in the final state) modify the input quark-diagram weak amplitudes. It is shown th

Andreas S. Kronfeld

Chiral fermions can (presumably) be constructed by introducing two regulators, one for the gauge fields (e.g. a lattice), and another for the fermion functional integrals in a fixed (regulated) gauge field. This talk discusses cutoff effects arising from the regulator of the fermions.

S. Aid

The cross section for the elastic photoproduction of \r0 mesons ($γp \to ρ^0 p$) has been measured with the H1 detector at HERA for two average photon-proton centre-of-mass energies of 55 and 187 GeV. TheFcenterline lower energy point was measured by observing directly the $ρ^{0}$ decay giving a cross section of $9.1\pm 0.9 (\stat)\pm 2.5 (\syst) μ$b. The lo

Alberto Saa

We perform the canonical quantization of a relativistic spinless particle moving in a curved and static spacetime. We show that the classical theory already describes at the same time both particle and antiparticle. The analyses involves time-depending constraints and we are able to construct the two-particle Hilbert space. The requirement of a static spacet

Alberto Saa

A new no-hair theorem is formulated which rules out a very large class of non-minimally coupled finite scalar dressing of an asymptotically flat, static, and spherically symmetric black-hole. The proof is very simple and based in a covariant method for generating solutions for non-minimally coupled scalar fields starting from the minimally coupled case. Such

Yong Baek Kim

Using the network model representation, it is shown that the edge states of finite-size integral quantum Hall liquid can be regarded as the edge states of an SU$(2N)$ open antiferromagnetic quantum spin chain in the $N \rightarrow 0$ limit. The structures of edge states in both cases of integer quantum Hall liquid and an SU$(2N)$ antiferromagnetic quantum sp

Erwin Frey, Uwe Claus Täuber, Terence Hwa

We investigate the noisy Burgers equation (Kardar--Parisi--Zhang equation in 1+1 dimensions) using the dynamical renormalization group (to two--loop order) and mode--coupling techniques. The roughness and dynamic exponent are fixed by Galilean invariance and a fluctuation--dissipation theorem. The fact that there are no singular two--loop contributions to th

Rajan Gupta, Pablo Tamayo

We present a status report on the ongoing analysis of the 3D Ising model with nearest-neighbor interactions using the Monte Carlo Renormalization Group (MCRG) and finite size scaling (FSS) methods on $64^3$, $128^3$, and $256^3$ simple cubic lattices. Our MCRG estimates are $K_{nn}^c=0.221655(1)(1)$ and $ν=0.625(1)$. The FSS results for $K^c$ are consistent

Gregor Tanner, Kai T. Hansen, Jorg Main

We present the first purely semiclassical calculation of the resonance spectrum in the Diamagnetic Kepler problem (DKP), a hydrogen atom in a constant magnetic field with $L_z =0$. The classical system is unbound and completely chaotic for a scaled energy $ε\sim E B^{-2/3}$ larger than a critical value $ε_c >0$. The quantum mechanical resonances can in semic

Francis Bernardeau

A lot of predictions for the statistical properties of the cosmic velocity field at large-scale have been obtained recently using perturbation theory. In this contribution I report the outcomes of a set of numerical tests that aim to check these results. Using Voronoi and Delaunay tessellations for defining the velocity field by interpolation between the par

Gian Luigi Granato, Luigi Danese, Alberto Franceschini

We investigate models for the power supply and broad-band spectral energy distribution (SED) of hyperluminous IR galaxies, recently discovered at high redshifts, in terms of the emission from an active nucleus embedded in a torus-like dusty structure. We find consistent solutions in terms of a simple torus model extended several hundreds of parsecs, with $A_

M. P. van Haarlem

We investigate the influence that projection effects have on the completeness of the the Abell cluster catalogue in the context of an $Ω_0$=1 CDM Universe. We construct a galaxy catalogue and identify clusters using an algorithm that mimics Abell&#39;s method. Over 30% of Richness Class $\geq$1 clusters have been selected despite not meeting the required int

Mordehai Milgrom

Very-low-surface-density galactic systems have very low mean accelerations. They thus provide quintessential tests of the Modified Dynamics (MOND), which predicts an increasing mass discrepancy with decreasing acceleration. We describe succinctly the results pertinent to several classes of such objects: Low-luminosity (dwarf) spirals, irregular dwarf spirals

Carolin Seitz, Peter Schneider

In a series of previous papers we have considered the reconstruction of the surface mass density of a cluster of galaxies from images of lensed faint background galaxies. We showed that the reconstructed surface mass density is not uniquely determined, but that there exists a global invariance transformation that leaves the shape of the images of the lensed

Carolin Seitz, Jean-Paul Kneib, Peter Schneider, Stella Seitz

The image distortions of high-redshift galaxies caused by gravitational light deflection of foreground clusters of galaxies can be used to reconstruct the two-dimensional surface mass density of these clusters. We apply an unbiased parameter-free reconstruction technique to the cluster CL0939+4713 (Abell 851), observed with the WFPC2 on board of the HST. We

L. P. Singh, P. K. Sahu

The effect of C-field in high density matter has been studied. We find that the negative energy and negative pressure of the C-field helps in formation of massive compact stable neutron stars of mass $\sim$ 0.5 solar mass which is in the range of 0.01 to 1.0 solar mass of recently observed dwarf stars.

Youngook Choi

In this paper, we give closed-form formulae for Severi degrees in cogenus 3 and 4 using Ran&#39;s method. These formulae coincide with those of I. Vainsencher and for cogenus 3 case, that of J. Harris and R. Pandharipande. Another result of this paper is that we calculate the degree of the polynomial $N(π,δ,d)$ in $d$, which is the degree of the locus of cur

M. J. Bergvelt, J. M. Rabin

We study the geometry and cohomology of algebraic super curves, using a new contour integral for holomorphic differentials. For a class of super curves (``generic SKP curves&#39;&#39;) we define a period matrix. We show that the odd part of the period matrix controls the cohomology of the dual curve. The Jacobian of a generic SKP curve is a smooth supermanif

K. Behrend

Gromov-Witten invariants for arbitrary projective varieties and arbitrary genus are constructed using the techniques from K. Behrend, B. Fantechi: The intrinsic normal cone.

K. Behrend, B. Fantechi

We suggest a construction of virtual fundamental classes of certain types of moduli spaces.

Alberto Saa

We examine exhaustively the behavior of avalanches in critical height sandpile models based in two- and three-dimensional lattices of various topologies. We get that for two-dimensional lattices the spatial and temporal distributions characterizing bulk avalanches do not depend on the lattice topology. For the three-dimensional case, we detect a small depend

Amr El-Zant

Much of standard galaxy dynamics rests on the implicit assumption that the corresponding N-body problem is (near) integrable. This notion although leading to great simplification is by no means a fact. It is therefore important to develop methods characterizing the stability of motion of N-body systems. A method based on the geometry of a system&#39;s phase

M. B. Halpern, N. A. Obers

The generalized Knizhnik-Zamolodchikov equations of irrational conformal field theory provide a uniform description of rational and irrational conformal field theory. Starting from the known high-level solution of these equations, we first construct the high-level conformal blocks and correlators of all the affine-Sugawara and coset constructions on simple g

V. A. Kazakov, M. Staudacher, T. Wynter

We exactly solve a special matrix model of dually weighted planar graphs describing pure two-dimensional quantum gravity with an R^2 interaction. It permits us to study the intermediate regimes between the gravitating and flat metric. Flat space is modeled by a regular square lattice, while localised curvature is introduced through lattice defects. No ``flat

Yan V. Fyodorov, H. -J. Sommers

By using the supersymmetry method we derive an explicit expression for the parametric correlation function of densities of eigenphases $θ_a$ of the S-matrix in a chaotic quantum system with broken time-reversal symmetry coupled to continua via M equivalent open channels;$\,\,a=1,..,M$ .We use it to find the distribution of derivatives of these eigenphases ov

A. A. Bolokhov, P. A. Bolokhov, T. A. Bolokhov, S. G. Sherman

We present the analysis of the phase space geometry of 2 $\rightarrow$ 3 reaction for the general case of nonzero and unequal particle masses. Its purpose is to elaborate an alternative approach to the problem of integration over phase space which does not exploit the Monte Carlo principle. The fast and effective algorithm of integration based on Gauss metho

Thomas Ackermann

A classical result in differential geometry due to Lichnerowicz [8] is concerned with the decomposition of the square of Dirac operators defined by Clifford connections on a Clifford module ${\cal E}$\ over a Riemannian manifold $M$. Recently, this formula has been generalized to arbitrary Dirac operators [2]. In this paper we prove a supersymmetric version

R. M. Noack, S. R. White, D. J. Scalapino

We present density-matrix renormalization group results for the ground state properties of two-leg Hubbard ladders. The half-filled Hubbard ladder is an insulating spin-gapped system, exhibiting a crossover from a spin-liquid to a band-insulator as a function of the interchain hopping matrix element. When the system is doped, there is a parameter range in wh

Wei Lu, Xue-Qian Li, Hai-Ming Hu

Making use of the collinear expansion technique developed by Ellis, Furmanski and Petrozio, and the special propagator concept invented by Qiu, we present a factorization approach to the photon fragmentation tensor for the inclusive Lambda hyperon production. As a result, the structure function $\tilde F$, which is related to the transverse polarization of t

Wei Lu, Jian-Jun Yang

We examined the symmetry aspect of the semi-inclusive one-pion production in the deep inelastic scattering of a lepton beam off an unpolarized nucleon target, with an emphasis on the positivity restrictions on the corresponding structure functions. In combination with the Callan-Gross-type relation between two twist-two structure functions $W_1$ and $W_2$, w

Chun-Gui Duan, Wei Lu

The positivity constraints to the structure functions for the inclusive spin-half baryon production by a time-like photon fragmentation are investigated. One conclusion is that $\hat F$, which arises from the hadronic final-state interactions, is subjected to an inequality between its absolute value and the two spin-independent structure functions. On the ba

B. E. C. Koltenbah, Robert Joynt

We present theoretical arguments and experimental support for the idea that high-Tc superconductivity can occur with s-wave, d-wave, or mixed-wave pairing in the context of a magnetic mechanism. The size and shape of the gap is different for different materials. The theoretical arguments are based on the t-J model as derived from the Hubbard model so that it

D. E. Kahana, S. H. Kahana, Y. Pang, A. J. Baltz

Deuteron coalescence, during relativistic nucleus-nucleus collisions, is carried out in a model incorporating a minimal quantal treatment of the formation of the cluster from its individual nucleons by evaluating the overlap of intial cascading nucleon wave packets with the final deuteron wave function. In one approach the nucleon and deuteron center of mass

H. Arfaei, S. Parvizi

We study the WZNW models based on nonstandard bilinear forms. We approach the problem from algebraic, perturbative and functional exact methods. It is shown that even in the case of integer $k$ we can find irrational CFT&#39;s. We prove that when the base group is noncompact with nonabelian maximal compact subgroup, the Kac-Moody representations are nonunita

Kenichi Horie

Possible geometric frameworks for a unified theory of gravity and electromagnetism are investigated: General relativity is enlarged by allowing for an arbitrary complex linear connection and by constructing an extended spinor derivative based on the complex connection. Thereby the spacetime torsion not only is coupled to the spin of fermions and causes a fou

D. M. Gitman, A. E. Gonçalves, I. V. Tyutin

A new pseudoclassical supersymmetrical model of a spinning particle in 2+1 dimensions is proposed. Different ways of its quantization are discussed. They all reproduce the minimal quantum theory of the particle.

Wolfgang Lucha, Franz F. Schöberl

The aim of these lectures is to give a self-contained introduction to nonrelativistic potential models, to their formulation as well as to their possible applications. At the price of some lack of (in a mathematical sense) rigorous derivations, we try to give a feeling and understanding for the simplest conceivable method to extract the explicit form of the

Nima Arkani-Hamed, Hsin-Chia Cheng, L. J. Hall

Supersymmetric theories involving a spontaneously broken flavor symmetry can lead to fermion masses which vanish at tree level but are generated by radiative corrections. In the context of supersymmetric theories with minimal low energy field content we discuss which fermion masses and mixings may be obtained radiatively, and find that constraints from flavo

Jian-Jun Yang, Bo-Qiang Ma, Guang-Lie Li

We investigate the non-perturbative effect in the nucleon structure function and the Gottfried sum by using a non-perturbative quark propagator with lowest dimensional condensate contributions from the QCD vacuum. It is shown that the non-perturbative effect modifies the conventional quark-parton model formula of the nucleon structure function at finite $Q^2

B. A. Muzykantskii, D. E. Khmelnitskii

We use optimal fluctuation method for a new ballistic $σ$-model to study the long time dispersion of conductance $G(t)$ of a mesoscopic sample. In the long time limit the conductance of a $d$-dimensional sample decays as $\exp (-A \ln^d t ) $. At shorter times the new results match those in our previous paper. It is found that at very long times the diffract

Hans Weber, Mats Wallin, Henrik Jeldtoft Jensen

We have studied the nonlinear current-voltage characteristic of a two dimensional lattice Coulomb gas by Monte Carlo simulation. We present three different determinations of the power-law exponent $a(T)$ of the nonlinear current-voltage characteristic, $V \sim I^{a(T)+1}$. The determinations rely on both equilibrium and non-equilibrium simulations. We find g

Ted Jacobson

The question of how to account for the outgoing black hole modes without drawing upon a transplanckian reservoir at the horizon is addressed. It is argued that the outgoing modes must arise via conversion from ingoing modes. It is further argued that the back-reaction must be included to avoid the conclusion that particle creation cannot occur in a strictly

J. Lopez, D. Nanopoulos, A. Zichichi

We re-examine the phenomenological aspects of a recently proposed string-derived SU(5)$\times$U(1) one-parameter supergravity model, and explore the sensitivity of the model predictions to variations in the strong coupling and the string unification scale. We also perform an analysis of the constraints on the parameter space of the model in light of the rece

David Persson

We calculate the effective Lagrangian for a magnetic field in spinor, scalar and vector QED. Connections are then made to $SU(N_C)$ Yang--Mills theory and QCD. The magnetization and the corresponding effective charge are obtained from the effective Lagrangian. The renormalized vacuum magnetization will depend on the renormalization scale chosen. Regardless o

W. -S. Zeng, J. Kuhl

The amplitude of displacive excitation of coherent phonons ({\it DECP}) in $YBa_2Cu_3O_7$ observed in time-resolved spectroscopy increases by a very large factor of 15 between 20 K (below $T_c$) and 100 K (above $T_c$). Microscopic modelling of phonon excitation reveals that these amplitude changes of the {\it $A_{1g}$} mode phonons are related to the existe

D. Ebert, T. Feldmann, C. Kettner, H. Reinhardt

We describe heavy baryons as bound states of a quark and a diquark. For this purpose we derive the Faddeev equation for baryons containing a single heavy quark from a Nambu-Jona-Lasinio type of model which is appropriately extended to include also heavy quarks. The latter are treated in the heavy mass limit. The heavy baryon Faddeev equation is then solved u