July 1995 arXiv papers — page 11

Hans-G. Kohrs

We investigate the effect of a direct pomeron coupling to quarks in DIS and photoproduction of jets. The direct pomeron coupling generates a point-like contribution to the diffractive part of the structure function $F_2$, which is analysed on the basis of the latest H1 data. Our model assumptions for the pomeron structure are consistent with the measured dat

Yitzhak Frishman, Amihay Hanany, Marek Karliner

We critically re-examine our earlier derivation of the effective low energy action for QCD in 4 dimensions with chiral fields transforming non-trivially under both color and flavor, using the method of anomaly integration. We find several changes with respect to our previous results, leading to much more compact expressions, and making it easier to compare w

K. Golec--Biernat, J. Kwieciński

The QCD analysis of deep inelastic diffractive scattering at HERA is performed assuming the dominance of the "soft" pomeron exchange and simple, physically motivated parametrization of parton distributions in the pomeron. Both the LO and NLO approximations are considered and the theoretical predictions concerning the quantity $R=F_L^D/F_T^D$ for diff

I. Kuss, H. Spiesberger

We derive exact expressions for luminosities of massive vector-boson pairs which can be used to describe the cross sections for processes in hadron collisions or $e^+e^-$ annihilation which proceed via two-vector-boson scattering. Our approach correctly takes into account the mutual influence of the emission of one vector boson on the emission of a second on

O. I. Piskounova

Leading charm production in reaction $π^- N \rightarrow DX$ is discussed.Three experiments at Fermilab and CERN have measured a rather large enhancement in production rate of leading $D^-$-mesons over nonleading $D^+$.A good description of these results is obtained in Quark Gluon String Model (QGSM) if the idea of 'intrinsic charm' is involved. The w

Michael C. Birse

Three commonly used types of effective theories for vector mesons are shown to correspond to different choices of interpolating field for spin-1 particles and the rules for transforming between them are described. The choice of fields that transform homogeneously under the nonlinear realisation of chiral symmetry imposes no preconceptions about the types of

Riotto Antonio

It has been recently argued that localized, unstable, but extremely long-lived configurations, called oscillons, could affect the dynamics of a first order electroweak phase transition in an appreciable way. Treating the amplitude and the size of subcritical bubbles as statistical degrees of freedom, we show that thermal fluctuations are not strong enough to

David Hochberg

We present a minisuperspace analysis of a class of Lorentzian wormholes that evolves quantum mechanically in a background Friedman Robertson Walker spacetime. The quantum mechanical wavefunction for these wormholes is obtained by solving the Wheeler-DeWitt equation for Einstein gravity on this minisuperspace. The time-dependent expectation value of the wormh

E. R. Mucciolo, B. D. Simons, A. V. Andreev, V. N. Prigodin

We examine the sensitivity of wavefunction intensities in chaotic quantum systems to small changes in an arbitrary external perturbation. A universal scaling is proposed for all three Dyson ensembles and a novel theoretical approach is used to determine exact expressions for systems which violate T-invariance. Analytical results are compared with numerical s

M. J. Rozenberg, G. Kotliar, H. Kajueter, G. A. Thomas

We study the transfer of spectral weight in the optical spectra of a strongly correlated electron system as a function of temperature and interaction strength. Within a dynamical mean field theory of the Hubbard model that becomes exact in the limit of large lattice coordination, we predict an anomalous enhancement of spectral weight as a function of tempera

Igor E. Aronov, Nikolai N. Beletskij

A new type of collective electromagnetic excitations, namely surface polaritons (SP) --- in a 2D electronic layer in a high magnetic field under Quantum Hall Effect (QHE) conditions is predicted. We have found the spectrum, damping, and polarization of the SP in a wide range of frequencies $ω$ and wavevectors $\bf k$. It is shown that near the Cyclotron Reso

P. Crehan

We prove that any spectral sequence obeying a certain growth law is the quantum spectrum of an equivalence class of classically integrable non-linear oscillators. This implies that exceptions to the Berry-Tabor rule for the distribution of quantum energy gaps of classically integrable systems, are far more numerous than previously believed. In particular we

Robert K. Schaefer, Andrew A. de Laix

We give an improved formalism for calculating the evolution of density fluctuations and temperature perturbations in flat universes. Our equations are general enough to treat the perturbations in collisionless relics like massive neutrinos. We find this formulation to be simpler to use than gauge dependent and other gauge-invariant formalisms. We show how to

Lin Wan, Ruth A. Daly

A sample of FRII radio sources in rich clusters of galaxies, both at high (z$\sim$0.5) and low (z$\sim$0) redshift, has been constructed to study the effect of environment on radio sources. Comparisons are made between the properties of FRII sources in cluster and non-cluster environments, and between X-ray clusters with and without FRII sources. The princip

A. Arriaga, V. R. Pandharipande, R. B. Wiringa

A detailed comparison of Faddeev and variational wave functions for $^3$H, calculated with realistic nuclear forces, has been made to study the form of three-body correlations in few-body nuclei. Three new three-body correlations for use in variational wave functions have been identified, which substantially reduce the difference with the Faddeev wave functi

Edward Frenkel, Andras Szenes

We consider the (A_n,A_1) Y-system arising in the Thermodynamic Bethe Ansatz. We prove the periodicity of solutions of this Y-system conjectured by Al.B. Zamolodchikov, and the dilogarithm identities conjectured by F. Gliozzi and R. Tateo.

M. A. Ivanov, T. Mizutani

A confined quark model study in a couple of chirally anomalous processes is presented in comparison with effective meson Lagrangian approaches of various kind. The processes considered are π^0 \to γγand γ\to π^+ π^- π^0 (or the equivalent πγ\to ππ) for which there is a well-known low energy theorem relating the latter amplitude with the former one by a very

Patrick Huet, Ann E. Nelson

The baryon density which may be produced during the electroweak phase transition in supersymmetric models is computed, taking into account the previously neglected effects of transport, strong and weak anomalous fermion number violation, thermal scattering, and a new method for computing \cp\ violating processes during the transition. We can account for the

R. G. Mints

We consider the flux jump instability of the Bean's critical state arising in the flux creep regime in type-II superconductors. We find the flux jump field, $B_j$, that determines the superconducting state stability criterion. We calculate the dependence of $B_j$ on the external magnetic field ramp rate, $\dot B_e$. We demonstrate that under the conditio

Doron Zeilberger

Dodgson's determinant condensation rule is shown to immediately imply the evaluation of MacMahon's determinant expression that leads to the Box Theorem.

H. J. de Vega, I. L. Egusquiza

The string equations of motion and constraints are solved near the horizon and near the singularity of a Schwarzschild black hole. In a conformal gauge such that $τ= 0$ ($τ$ = worldsheet time coordinate) corresponds to the horizon ($r=1$) or to the black hole singularity ($r=0$), the string coordinates express in power series in $τ$ near the horizon and in p

Owe Philipsen

I calculate the rate of $B+L$ violating processes in the ``symmetric" phase of the Standard Model by means of semiclassical methods, which are based on an appropriately resummed loop expansion within the dimensionally reduced theory. The rate is found to reach its asymptotic form $Γ/V=c(\a_W T)^4$ at a temperature about three times the critical temperatu

Giampiero Esposito, Gennaro Miele, Luigi Rosa

Dirac's theory of constrained Hamiltonian systems is applied to the minimal conformally invariant SU(5) grand-unified model studied at 1-loop level in a de Sitter universe. For this model, which represents a simple and interesting example of GUT theory and at the same time is a step towards theories with larger gauge group like SO(10), second-class const

Giampiero Esposito, Alexander Yu. Kamenshchik

This paper studies a new set of mixed boundary conditions in Euclidean quantum gravity. These involve, in particular, Robin boundary conditions on the perturbed 3-metric and hence lead, by gauge invariance, to Robin conditions on the whole ghost 1-form. The corresponding trace anomaly is evaluated in the case of flat Euclidean 4-space bounded by a 3-sphere.

Sumathi Rao, Diptiman Sen

We study the Heisenberg antiferromagnetic chain with both dimerization and frustration. The classical ground state has three phases: a Neel phase, a spiral phase and a colinear phase. In each phase, we discuss a non-linear sigma model field theory governing the low energy excitations. We study the theory in the spiral phase in detail using the renormalizatio

Piero Olla

The fluctuations in the particle size distribution for processes of fragmentation and aggregation are studied for stationary state regimes. The system is described in terms of a stochastic process over an adequate tree structure. The RMS fluctuations appear to scale with the square root of the mean distribution, as in the case of sums of statistically indepe

Rachel A. Pildis

The very high apparent galaxy densities in Hickson compact groups (HCGs) should produce copious amounts of galaxy-galaxy interaction, if these groups are bound dynamical units. I examine the evidence for such interactions in HCG 94, a group of seven galaxies with an envelope of diffuse optical light and an extremely high X-ray luminosity. Using $ROSAT$ HRI d

J. Maharana, H. Singh

Classical solutions for a four-dimensional Minkowskian string effective action and an Euclidean one with cosmological constant term are derived. The former corresponds to electrovac solutions whereas the later solutions are identified as gravitational instanton solutions for Fubini-Study metric. The symmetries of the effective actions are identified and new

Gaetano Fiore

We review the Euclidean Hopf algebra $U_q(e^N)$ dual of $Fun(\rn_q^N\lcross SO_{q^{-1}}(N))$ and describe its fundamental Hilbert space representations \cite{fioeu}, which turn out to be rather simple "lattice-regularized" versions of the classical ones, in the sense that the spectra of squared momentum components are discrete and the corresponding e

A. Carlini, V. P. Frolov, M. B. Mensky, I. D. Novikov

We consider the action principle to derive the classical, non-relativistic motion of a self-interacting particle in a 4-D Lorentzian spacetime containing a wormhole and which allows the existence of closed time-like curves. For the case of a `hard-sphere' self-interaction potential we show that the only possible trajectories (for a particle with fixed in

N. Christopher Phillips

Starting from Kirchberg's theorems announced in 1994, namely O_2 tensor A is isomorphic to O_2 for separable unital nuclear simple A and O_infinity tensor A is isomorphic to A if in addition A is purely infinite, we prove that KK-equivalence implies isomorphism for nonunital separable nuclear purely infinite simple C*-algebras. It follows that if A and B are

O. Heinonen, M. I. Lubin, M. D. Johnson

We develop an ensemble density functional theory for the fractional quantum Hall effect using a local density approximation. Model calculations for edge reconstructions of a spin-polarized quantum dot give results in good agreement with semiclassical and Hartree-Fock calculations, and with small system numerical diagonalizations. This establishes the usefuln

I. G. Korepanov

This paper is devoted to constructing and studying exactly solvable dynamical systems in discrete time obtained from some algebraic operations on matrices, to reductions of such systems leading to classical field theory models in 2+1-dimensional wholly discrete space-time, and to connection between those field theories and inhomogoneous models in 2-dimension

James T. Rogers

Let $f$ be a polynomial map of the Riemann sphere of degree at least two. We prove that if $f$ has a Siegel disk $G$ on which the rotation number satisfies a diophantine condition, then the boundary of $G$ contains a critical point.

Judy A. Kennedy, James A. Yorke

We describe an example of a $C^\infty$ diffeomorphism on a 7--manifold which has a compact invariant set such that uncountably many of its connected components are pseudocircles. (Any 7--manifold will suffice.) Furthermore, any diffeomorphism which is sufficiently close (in the $C^1$ metric) to the constructed map has a similar invariant set, and the dynamic

Robert M. May

This is an outline of my Gibbs Lecture to the American Mathematical Society in January 1994; it is essentially a sign-posted guide to a still-developing literature.

Claudio Coriano', Rajesh R. Parwani

We study the effect of nonzero temperature on the induced electric charge around a Dirac monopole. While at zero temperature the charge is known to be proportional to a CP violating $θ$ parameter, we find that at high temperature the charge is proportional to sin $θ$. Other features of the charge at nonzero temperature are discussed. We also compute the indu

Dae Sung Hwang, C. S. Kim, Wuk Namgung

We investigate the $B$ and $D$ mesons in the relativistic quark model by applying the variational method with the Gaussian wave function. We calculate the Fermi momentum parameter $p_{_F}$, and obtain $p_{_F} = 0.50 \sim 0.54$ GeV, which is almost independent of the input parameters, $α_s$, $m_b$, $m_c$ and $m_{sp}$. We then calculate the ratio $f_B$/$f_D$,

Franco Buccella, Giampiero Esposito, Gennaro Miele

This paper studies one-loop effective potential and spontaneous-symmetry-breaking pattern for SU(5) gauge theory in de Sitter space-time. Curvature effects modify the flat-space effective potential by means of a very complicated special function previously derived in the literature. An algebraic technique already developed by the first author to study sponta

Giampiero Esposito

This paper studies necessary conditions for the existence of alpha-surfaces in complex space-time manifolds with nonvanishing torsion. For these manifolds, Lie brackets of vector fields and spinor Ricci identities contain explicitly the effects of torsion. This leads to an integrability condition for alpha-surfaces which does not involve just the self-dual W

Giampiero Esposito

This paper compares recent approaches appearing in the literature on the singularity problem for space-times with nonvanishing torsion.

Giampiero Esposito

At first we introduce the space-time manifold and we compare some aspects of Riemannian and Lorentzian geometry such as the distance function and the relations between topology and curvature. We then define spinor structures in general relativity, and the conditions for their existence are discussed. The causality conditions are studied through an analysis o

Kip S. Thorne

This article reviews current efforts and plans for gravitational-wave detection, the gravitational-wave sources that might be detected, and the information that the detectors might extract from the observed waves. Special attention is paid to (i) the LIGO/VIRGO network of earth-based, kilometer-scale laser interferometers, which is now under construction and

R. Bergmann, W. Wilke

ion is one of the most promising approaches to improve the performance of problem solvers. In several domains abstraction by dropping sentences of a domain description -- as used in most hierarchical planners -- has proven useful. In this paper we present examples which illustrate significant drawbacks of abstraction by dropping sentences. To overcome these

Michael R. Geller

We extend a theorem of Bloch, which concerns the net orbital current carried by an interacting electron system in equilibrium, to include mesoscopic effects. We obtain a rigorous upper bound to the allowed ground-state current in a ring or disc, for an interacting electron system in the presence of static but otherwise arbitrary electric and magnetic fields.

Ling-Lie Chau, Ding-Wei Huang

We give a mean-field calculation for the odd-resonating-valence-bond ORVB pairing scheme. We obtain interesting quasi-particle excitation energy $E_{\bf k}$ as a function of momentum ${\bf k}$. It is distinctively different from those of the $d_{x^2-y^2}$-wave, the anisotropic-s-wave, and the p-wave. It is a gapless theory for superconductivity with well def

Hisatoshi Yokoyama, Masao Ogata

The one-dimensional (1D) $t$-$J$ model is investigated by using a Gutzwiller-Jastrow-type variation method and the exact diagonalization of small systems. Variational expectation values are estimated by the variational Monte Carlo method with sufficient accuracy. First, we represent the diagonalization results. Physical quantities like momentum distribution

Michael White

In this paper, I argue, contrary to the prevailing opinion in the linguistics and philosophy literature, that a sortal approach to aspectual composition can indeed be explanatory. In support of this view, I develop a synthesis of competing proposals by Hinrichs, Krifka and Jackendoff which takes Jackendoff's cross-cutting sortal distinctions as its point

D. S. Salopek

The nature of cosmic time is illuminated using Hamilton-Jacobi theory for general relativity. For problems of interest to cosmology, one may solve for the phase of the wavefunctional by using a line integral in superspace. Each contour of integration corresponds to a particular choice of time hypersurface, and each yields the same answer. In this way, one ca