August 1995 arXiv papers

Omos Ori, Eanna Flanagan

The spacetime singularities inside realistic black holes are sometimes thought to be spacelike and strong, since there is a generic class of solutions (BKL) to Einsteins equations with these properties. We show that null, weak singularities are also generic, in the following sense: there is a class of vacuum solutions containing null, weak singularities, dep

Tiehui, Liu

The search for $D^0\bar{D}^0$ mixing may carry a large discovery potential for new physics. This paper discusses the techniques, current experimental status, and future prospects for the mixing search. Some new ideas, applicable to future mixing searches, are introduced. In this paper, the importance of separately measuring the decay rate difference and the

Lee Smolin

An approach to quantum gravity and cosmology is proposed based on a synthesis of four elements: 1) the Bekenstein bound and the related holographic hypothesis of 't Hooft and Susskind, 2) topological quantum field theory, 3) a new approach to the interpretational issues of quantum cosmology and 4) the loop representation formulation of non-perturbative q

David M. Pierce

Threshold corrections to the running of gauge couplings are calculated for superstring models with free complex world sheet fermions. For two N=1 $SU(2)\times U(1)^5$ models, the threshold corrections lead to a small increase in the unification scale. Examples are given to illustrate how a given particle spectrum can be described by models with different bou

Joseph K. Daugherty, Alice K. Harding

We have used a Monte Carlo simulation of a Polar Cap (PC) model of gamma-ray pulsars to estimate light curves and phase-resolved spectra for sources whose rotational and magnetic axes are oriented so that only one of the magnetic poles produces emission directed at the Earth. In this Single Polar Cap (SPC) scenario, even sources whose light curves have two d

M. van der Burgt, V. C. Karavolas, F. M. Peeters, J. Singleton

Magnetotransport properties of a pseudomorphic GaAs/Ga0.8In0.2As/Ga0.75Al0.25As heterostructure are investigated in pulsed magnetic fields up to 50 T and at temperatures of T=1.4 K and 4.2 K. The structure studied consists of a Si delta-layer parallel to a Ga0.8In0.2As quantum well (QW). The dark electron density of the structure is n_e=1.67x 10^16 m^-2. By

J. Schmalzing, M. Kerscher, T. Buchert

Minkowski functionals provide a novel tool to characterize the large-scale galaxy distribution in the Universe. Here we give a brief tutorial on the basic features of these morphological measures and indicate their practical application for simulation data and galaxy redshift catalogues as examples.

A. C. Irving, R. Kenna

We use finite--size scaling of Lee--Yang partition function zeroes to study the critical behaviour of the two dimensional step or sgn $O(2)$ model. We present evidence that, like the closely related $XY$--model, this has a phase transition from a disordered high temperature phase to a low temperature massless phase where the model remains critical. The criti

J. M. Izquierdo, N. D. Lambert, G. Papadopoulos, P. K. Townsend

We present dyonic multi-membrane solutions of the N=2 D=8 supergravity theory that serves as the effective field theory of the $T^2$-compactified type II superstring theory. The `electric' charge is fractional for generic asymptotic values of an axion field, as for D=4 dyons. These membrane solutions are supersymmetric, saturate a Bogomolnyi bound, fill

Eugene Levin

Soft photon and gluon radiation off a fast quark propagating through nuclear matter is discussed. The close anology between the Landau - Pomeranchuk - Migdal (LPM) effect in QED and the emission of soft gluons, suggested in ref. \cite{BDPS} for ``hot" plasma, is confirmed and the relation between Mueller's approach and traditional calculations is est

Georg Junker, Harald Karl, Hajo Leschke

The classical and quantum dynamics for an n-dimensional generalization of the kicked planar (n=1) rotator in an additional effective centrifugal potential. Therefore, typical phenomena like the diffusion in classical phase space are similar to that of the one-dimensional model. For the quantum dynamics such a result is not expected as in this case the evolut

A. C. Irving, J. C. Sexton

We study the quenched and unquenched lattice Schwinger model with Wilson fermions. The lowest non-trivial order of the systematic expansion recently proposed by Sexton and Weingarten is shown to allow good estimates of long distance physics from quenched configurations. Results for the static potential and the lowest bound state mass are presented.

J. Rolf, C. Wieczerkowski

We compute the hierarchical $ϕ^4$-trajectory in terms of perturbation theory in a running coupling. In the three dimensional case we resolve a singularity due to resonance of power counting factors in terms of logarithms of the running coupling. Numerical data is presented and the limits of validity explored. We also compute moving eigenvalues and eigenvecto

I. T. Habibullin

The problem of construction of the boundary conditions for nonlinear equations is considered compatible with their higher symmetries. Boundary conditions for the sine-Gordon, Jiber-Shabat and KdV equations are discussed. New examples are found for the Jiber-Shabat equation.

M. Jetter

The decay $η\to π^0 γγ$ is discussed in the framework of SU(3) chiral perturbation theory. The process is dominated by the ${\cal{O}}(p^6)$ in the momentum expansion where tree-level amplitudes from the effective Lagrangian ${\cal{L}}^6$ enter together with one--loop contributions from ${ \cal{L}}^4$ and two--loop contributions from ${\cal{L}}^2$. We estimat

S. Pepin, Fl. Stancu, W. Koepf, L. Wilets

The present work is an extension of a previous study of the nucleon-nucleon interaction based on the chromo-dielectric soliton model. The former approach was static, leading to an adiabatic potential. Here we perform a dynamical study in the framework of the Generator Coordinate Method. In practice, we derive an approximate Hill-Wheeler differential equation

Massimiliano Ciuchini, J. A. Gracey

We use the large $N$ self consistency method to compute the critical exponents of the fields and coupling of the supersymmetric CP(N) sigma model at leading order in $1/N$ in various dimensions. We verify that the correction to the critical beta-function slope vanishes at O(1/N) which is consistent with supersymmetry. The three dimensional model is investiga

G. Papadopoulos

We present new supersymmetric extensions of Conformal Toda and $A^{(1)}_N$ Affine Toda field theories. These new theories are constructed using methods similar to those that have been developed to find supersymmetric extensions of two-dimensional bosonic sigma models with a scalar potential. In particular, we show that the Conformal Toda field theory admits

O. M. Khudaverdian

It is a review of some results in Odd symplectic geometry related to the Batalin-Vilkovisky Formalism

A. Niemeyer, H. P. Nilles

The mechanism of gaugino condensation has emerged as a prime candidate for supersymmetry breakdown in low energy effective supergravity (string) models. One of the open questions in this approach concerns the size of the gauge coupling constant which is dynamically fixed through the vev of the dilaton. We argue that a nontrivial gauge kinetic function $f(S)$

Kazuto Oshima

We examine supersymmetric quantum mechanics on $SO(4)$ to realize Witten's idea. We find instanton solutions connecting approximate vacuums. We calculate Hessian matrices for these solutions to determine true vacuums. Our result is in agreement with de Rham cohomology of $SO(4)$. We also give a criterion for cancellation of instanton effects for a pair o

Keith A. Olive

The effect of CP violating phases in the MSSM on the relic density of the lightest supersymmetric particle (LSP) is considered. In particular, the upper limits on the LSP mass are relaxed when phases in the MSSM are allowed to take non-zero values and when the LSP is predominantly a gaugino (bino). Previous limits of $\mb \la 250$ GeV for $Ωh^2 < 0.25$ can b

Chi-Keung Chow, Dan Pirjol

This is the continuation of a previous article, in which the Bjorken and Voloshin sum rules were interpreted as statements of conservation of probability and energy. Here the formalism is extended to higher moments of the Hamiltonian operator. From the conservation of the second moment of the Hamiltonian operator one can derive a sum rule which, in the small

Xiao-Gang He, G. Valencia

The $\cp$ violating asymmetry $A(Λ^0_-)$ has been estimated to occur at the level of a few times $10^{-5}$ within the minimal standard model. The experiment E871 expects to reach a sensitivity of $10^{-4}$ to the asymmetry $A(Λ^0_-)+A(Ξ^-_-)$. In this paper we study some of the implications of such a measurement for $\cp$ violation beyond the minimal standar

G. Piller, A. W. Thomas

We investigate the sensitivity of $J/Ψ$ production in proton-neutron and proton-deuteron collisions to charge symmetry violations in the parton distributions as well as to nuclear corrections. It is found that the effects of charge symmetry violations in the quark distributions are confined to large $x_F$ and difficult to measure in experiments currently bei

Michael Krämer

We present a complete calculation of the higher-order perturbative QCD corrections to inelastic photoproduction of $J/ψ$ particles. A comprehensive analysis of total cross sections and differential distributions for the energy range of the fixed-target experiments and for inelastic $J/ψ$ photoproduction at HERA is performed. The cross section and the $J/ψ$ e

I. I. Bigi

Over the last few years a theoretical treatment for the weak decays of heavy-flavour hadrons has been developed that is genuinely based on QCD. Its methodology is described as it applies to total lifetimes, and the underlying theoretical issues are discussed. Theoretical expectations are compared with present data. One discrepancy emerges: the beauty baryon

C. Chicone, B. Mashhoon, D. Retzloff

The long term perturbation of a Newtonian binary system by an incident gravitational wave is discussed in connection with the issue of gravitational ionization. The periodic orbits of the planar tidal equation are investigated and the conditions for their existence are presented. The possibility of ionization of a Keplerian orbit via gravitational radiation

G. Michaud, R. C. Myers

The two-dimensional CGHS model provides an interesting toy-model for the study of black hole evaporation. For this model, a quantum effective action, which incorporates Hawking radiation and backreaction, can be explicitly constructed. In this paper, we study a generalization of this effective action. In our extended model, it is possible to remove certain c

Z. Li, L. Schülke, B. Zheng

We simulate the critical relaxation process of the two-dimensional Ising model with the initial state both completely disordered or completely ordered. Results of a new method to measure both the dynamic and static critical exponents are reported, based on the finite size scaling for the dynamics at the early time. From the time-dependent Binder cumulant, th

Markus Böhm, Kurt Broderix, Hajo Leschke

For an electron in the plane subjected to a perpendicular constant magnetic field and a homogeneous Gaussian random potential with a Gau{ss}ian covariance function we approximate the averaged density of states restricted to the lowest Landau level. To this end, we extrapolate the first 9 coefficients of the underlying continued fraction consistently with the

Shu Zhang, Gerhard Müller

The $T=0$ dynamics of the two-dimensional $s=1/2$ Heisenberg model with competing nearest-neighbor $(J_1)$ and next-nearest-neighbor $(J_2)$ interactions is explored via the recursion method, specifically the frequency-dependent fluctuations of the order parameters associated with some of the known or suspected ordering tendencies in this system, i.e. Néel,

Yoshihiko Nonomura, Yukiyasu Ozeki

Ground-state properties of the two-dimensional $S=1/2$ random Heisenberg models are investigated by the exact-diagonalization method. The phase diagram of the bond-random model (the $\pm J$ model) is the same as that of the corresponding Ising spin glass model, in spite of quantum fluctuation. In the site-random model, the spin glass phase exists at least in

Yukiyasu Ozeki, Yoshihiko Nonomura

The site-random Ising spin glass model is investigated. We find a rigorous symmetry for the SG correlation and the free energy, which provides some restrictions in the phase diagram. Using the defect energies calculated by the numerical transfer matrix method, we obtain evidence for the existence of the SG phase in the two-dimensional Ising system. We sugges

M. Kiometzis, H. Kleinert, A. M. J. Schakel

The dual approach to the Ginzburg-Landau theory of a Bardeen-Cooper-Schrieffer superconductor is reviewed. The dual theory describes a grand canonical ensemble of fluctuating closed magnetic vortices, of arbitrary length and shape, which interact with a massive vector field representing the local magnetic induction. When the critical temperature is approache

Mercè Ollé, Daniel Pfenniger

The properties of motion close to the transition of a stable family of periodic orbits to complex instability is investigated with two symplectic 4D mappings, natural extensions of the standard mapping. As for the other types of instabilities new families of periodic orbits may bifurcate at the transition; but, more generally, families of {\sl isolated invar

Martin White, Douglas Scott

We consider structure formation and CMB anisotropies in a closed universe, both with and without a cosmological constant. The CMB angular power spectrum and the matter transfer function are presented, along with a discussion of their relative normalization. This represents the first full numerical evolution of density perturbations and anisotropies in a sphe

Arif Babul, Henry C. Ferguson

Both theoretical and observational lines of reasoning suggest that the very faint (B > 24) galaxies seen in deep images of the sky are small low-mass galaxies that experienced starburst at 0.5<z<1 and have since faded into low luminosity, low surface brightness objects. We scrutinize this hypothesis in order to determine whether such a model can account for

F. Durret, A. Biviano, D. Gerbal, O. Le Fevre

Recent observations of the Coma cluster of galaxies in its central region have provided approximately 250 new redshifts - allowing a good membership criterion to be established for brighter galaxies - and magnitudes for 8000 objects in the same region derived from photometric data complete up to V$_{26.5}$=22.5. A thorough structural study of the galaxy dist

Fabio Governato, Paolo Tozzi, Alfonso Cavaliere

We study the formation and the evolution of galaxy groups in a critical universe, showing the importance of secondary infall for their dynamical evolution. Merging is only slightly accelerated if galaxies have massive halos, because the mass initially associated to the individual galaxies is soon tidally stripped. Stripping is particularly effective for infa

C. H. Heller, I. Shlosman

We investigate the dynamical response of stellar orbits in a rotating barred galaxy potential to the perturbation by a nuclear gaseous ring. The change in 3D periodic orbit families is examined as the gas accumulates near the inner Lindblad resonance. It is found that the x2/x3 loop extends to higher Jacobi energy and a vertical instability strip forms in ea

Armando Pisani

A general method is described for detecting and analysing galaxy systems. The multivariate geometrical structure of the sample is studied by using an extension of the method which we introduced in a previous paper. The method is based on an estimate of the probability density underlying a data sample. The density is estimated by using an iterative and adapti

A. Biviano, P. Katgert, A. Mazure, M. Moles

By using the ENACS data, we have studied the properties of emission-line galaxies (ELG) in clusters. The fraction of ELG in clusters is 16~%; this fraction is slightly dependent on the cluster velocity dispersion, being larger for ``colder&#39;&#39; systems. ELG tend to occur more frequently than other cluster galaxies in substructures. However, only a minor

Scott Burles, David Tytler

We have conducted the first survey for Oxygen VI $λλ1032,1038$ absorption lines in QSO spectra. We used medium resolution ($R \approx 1300$) high signal-to-noise ($\approx 20$) Faint Object Spectrograph spectra of 11 QSOs ($0.53\leq$\zem$\leq2.08$) from the Hubble Space Telescope Archive. We use simulated spectra to determine the significance of the line ide

G. Parzen

This paper defines the beta function and other linear orbit parameters using the exact equations of motion. The orbit functions are redefined using the exact equations. Expressions are found for the transfer matrix and the emittances. Differential equations are found for the beta function and the eta function. New relationships between the linear orbit param

Moshe Elitzur, V. Bujarrabal

We present the analytical solution of a maser shaped like a spherical shell. We determine the general condition on the size of the central cavity at which a sphere becomes a shell maser, and derive the intensity, beaming angle and observed size of both unsaturated and saturated shells.

Guy D. Moore

We investigate analytically the fermionic fluctuation determinant at finite temperatures in the minimal standard model, including all operators up to dimension 6 and all contributions to the effective potential to all orders in the high $T$ expansion, to 1 loop. We apply the results to find corrections to the Sphaleron erasure rate in the broken phase. We co

B. W. Harris, J. Smith, R. Vogt

A calculation of the next-to-leading order exclusive extrinsic charm quark differential distributions in deeply inelastic electroproduction has recently been completed. Using these results we compare the NLO extrinsic contributions to the charm structure function $F_2(x,Q^2,m_c^2)$ with the corresponding NLO intrinsic contributions. The results of this analy

Jacek Dziarmaga

We present a new derivation of the Berry phase picked up during exchange of parallel vortices. This derivation is based on the Bogolubov - de Gennes formalism. The origin of the Magnus force is also critically reanalised. The Magnus force can be interpreted as interaction with effective magnetic field. The efective magnetic field may be even of the order $10

Frank Cuypers

We perform a model independent analysis of the production of scalar and vector leptoquarks in the $e^-γ$ mode of a linear collider of the next generation. Since these leptoquarks are produced singly, higher masses can be probed than in other collider modes, like $e^+e^-$ scattering. We discuss the discovery potential and show how polarization and angular dis

Peter W. Shor

A digital computer is generally believed to be an efficient universal computing device; that is, it is believed able to simulate any physical computing device with an increase in computation time of at most a polynomial factor. This may not be true when quantum mechanics is taken into consideration. This paper considers factoring integers and finding discret

Erasmo Recami, Giovanni Salesi

In previous papers, we have investigated the classical theory of Barut and Zanghi (BZ) for the electron spin [which interpreted the Zitterbewegung (zbw) motion as an internal motion along helical paths], and its &#34;quantum&#34; version, by using the language of Clifford algebras. And, in so doing, we ended with a new non-linear Dirac-like equation (NDE). W

S. Groote, J. G. Körner

We present the results of an O(alpha_s) calculation of the transverse polarization of top quarks produced in e+e- annihilation. In a first step we determine the transverse polarization of the top with regard to the hadron plane spanned by the (q,bar q,g) system. We then rotate the transverse components of the polarization to the lepton plane spanned by the (

Shijong Ryang

We construct the Picard-Fuchs equations of the $N=2$ supersymmetric $SU(2)$ gauge theories with $N_f=0,1,3$ matter multiplets. For the $N_f=0$ theory from the solutions of the Picard-Fuchs equation the monodromy matrices on the quantum moduli space are determined. We analyze the Seiberg-Witten solutions to compute monodromies exactly and present the instanto

Seungjoon Hyun, Jaemo Park, Jae-Suk Park

We study the path integral of a twisted $N=2$ supersymmetric Yang-Mills theory coupled with hypermultiplet having the bare mass. We explicitly compute the topological correlation functions for the $SU(2)$ theory on a compact oriented simply connected simple type Riemann manifold with $b_2^+ \geq 3$. As the corollaries, we determine the topological correlatio

Tetsu Yajima, Katsuhiro Nishinari

The Davey-Stewartson (DS) equations with a perturbation term are presented by taking a fluid system as an example on an uneven bottom. Stability of dromions, solutions of the DS equations with localized structures, against the perturbation is investigated numerically. Dromions decay exponentially under an effect of the perturbation, while they travel stably

C. R. Hofmann, G. Soff, J. Reinhardt, W. Greiner

We calculate the spatial correlation of electrons and positrons emitted by internal pair conversion of Coulomb excited nuclei in heavy ion collisions. The alignment or polarization of the nucleus results in an anisotropic emission of the electron-positron pairs which is closely related to the anisotropic emission of $γ$-rays. However, the angular correlation

Mannque Rho

The changes of hadron properties in dense and/or hot matter are discussed in terms of effective chiral Lagrangians with the parameters of the theory scaled in a simple way. The phenomenologically successful Walecka model is identified as a mean field chiral Lagrangian with the scaled parameters. Kaon condensation and chiral restoration transitions can be des

Zhe Chang

This is a self-contained review on the theory of quantum group and its applications to modern physics. A brief introduction is given to the Yang-Baxter equation in integrable quantum field theory and lattice statistical physics. The quantum group is primarily introduced as a systematic method for solving the Yang-Baxter equation. Quantum group theory is pres

E. I. Guendelman, A. V. Leonidov, V. A. Nechitailo, D. A. Owen

We report the calculation of the fourth coefficient in an expansion of the heat kernel of a non-minimal, non-abelian kinetic operator in an arbitrary background gauge in arbitrary space-time dimension. The fourth coefficient is shown to bring a nontrivial gauge dependence due to the contribution of the lowest order off-shell gauge invariant structure.

E. Elizalde

We bring together two apparently disconnected lines of research (of mathematical and of physical nature, respectively) which aim at the definition, through the corresponding zeta function, of the determinant of a differential operator possessing, in general, a complex spectrum. It is shown explicitly how the two lines have in fact converged to a meeting poin

Ron Folman, Erasmo Recami

We present a brief overview of the different kinds of electromagnetic radiations expected to come from (or to be induced by) space-like sources (tachyons). New domains of radiation are here considered; and the possibility of experimental observation of tachyons via electromagnetic radiation is discussed.

Shogo Tanimura, Izumi Tsutsui

The path integral on a homogeneous space $ G/H $ is constructed, based on the guiding principle `first lift to $ G $ and then project to $ G/H $&#39;. It is then shown that this principle admits inequivalent quantizations inducing a gauge field (the canonical connection) on the homogeneous space, and thereby reproduces the result obtained earlier by algebrai

Erasmo Recami

Some recent experiments led to the claim that something can travel faster than light in vacuum. However, such results do not seem to place relativistic causality in jeopardy. Actually, it is possible to solve also the known causal paradoxes, devised for "faster than $c$" motion: even if this is not widely recognized. Here we want to show, in detail and rigor

J. L. Boldo, B. M. Pimentel, J. L. Tomazelli

The operator ${\bf S}$ in Fock space which describes the scattering and particle production processes in an external time-dependent electromagnetic potential $A$ can be constructed from the one-particle S-matrix up to a physical phase $λ[A]$. In this work we determine this phase for $QED$ in (2+1) dimensions, by means of causality, and show that no ultraviol

Eric Braaten, Agustin Nieto

The free energy for QCD at high temperature $T$ is calculated to order $g^5$ using effective-field-theory methods to separate the contributions from the momentum scales $T$ and $gT$. The effects of the scale $T$ enter through the coefficients in the effective lagrangian for the 3-dimensional effective theory obtained by dimensional reduction. The perturbatio

J. M. Moreno, D. H. Oaknin, M. Quirós

We consider the top-bottom doublet in the background of the sphaleron for the realistic case of large non-degeneracy of fermion masses, in particular $m_b=5$ GeV and $m_t=175$ GeV. We propose an axially symmetric $(r,θ)$-dependent ansatz for fermion fields and investigate the effects of the non-degeneracy on them. The exact solution is described, with an err

K. C. Chou, Y. L. Wu

Fermion masses and mixing angles including that of neutrinos are studied in a model with symmetry group SUSY $SO(10)\times Δ(48) \times U(1)$. Universality of Yukawa coupling of superfields is assumed. The resulting texture of mass matrices in the low energy region depends only on a single coupling constant and VEVs caused by necessary symmetry breaking. 13

D. Graudenz, G. Veneziano

Using a recently proposed factorization hypothesis for semi-inclusive hard processes in QCD, one can study, in principle, the diffractive production of the Standard Model Higgs boson at LHC using only, as input, $ep$ diffractive hard-processes data of the type recently collected and analyzed by the H1 and ZEUS collaborations at HERA. While waiting for a more

A. Dobrovolskaya, V. Novikov

We consider the factorization method in the spontaneously broken gauge theories such as the electroweak theory. Using the of\/f-shell $W$-boson density matrix formalism we demonstrate that the factorization conditions are completely under control. The main point of this paper is the presence of the &#34;interference&#34; or &#34;crossed&#34; terms in $WW$--s

F. M. Steffens, H. Holtmann, A. W. Thomas

We compute the full x - dependence of the proton and neutron spin structure functions in the MIT bag model, including the effect of gluon exchange and the meson cloud. Impressive agreement is found for x larger than 0.1, where polarised gluons are not expected to play a significant role.

F. Abe

We report on measurements of differential $μ- {\bar b}$ cross sections, where the muon is from a semi-leptonic $b$ decay and the ${\bar b}$ is identified using precision track reconstruction in jets. The semi-differential correlated cross sections, d$σ$/d$\Et^{\bar b}$, d$σ$/d$\pt^{\bar b}$, and d$σ$/d$δϕ(μ- {\bar b})$ for $\pt^μ>$~9 GeV/c, $|η^μ|<$~0.6, $\E

Martin Utley

Preliminary results are presented from a study of dijet photoproduction in ep collisions with both virtual and quasi-real photons at the ZEUS detector. Samples of events with photons of virtuality $P^2$ in the ranges $0.1 < P^2 < 0.55$ GeV$^2$ and $P^2 < 0.02$ GeV$^2$ having two jets of $E_T^{jet} > 4$ GeV in the final state have been obtained. For both quas

Marco Cavaglia`, Vittorio de Alfaro, Alexandre T. Filippov

We quantize by the Dirac - Wheeler-DeWitt method the canonical formulation of the Schwarzschild black hole developed in a previous paper. We investigate the properties of the operators that generate rigid symmetries of the Hamiltonian, establish the form of the invariant measure under the rigid transformations, and determine the gauge fixed Hilbert space of

Giampiero Esposito, Cosimo Stornaiolo

Recent work in the literature has shown that general relativity can be formulated in terms of a jet bundle which, in local coordinates, has five entries: local coordinates on Lorentzian space-time, tetrads, connection one-forms, multivelocities corresponding to the tetrads and multivelocities corresponding to the connection one-forms. The derivatives of the

Quo-Shin Chi, Sergey A. Merkulov, Lorenz J. Schwachhöfer

In 1955, Berger \cite{Ber} gave a list of irreducible reductive representations which can occur as the holonomy of a torsion-free affine connection. This list was stated to be complete up to possibly a finite number of missing entries. In this paper, we show that there is, in fact, an infinite family of representations which are missing from this list, there

J. Schmalian, W. Hübner

The nonlinear magneto-optical response of $s$- and $d$-wave superconductors is discussed. We carry out the symmetry analysis of the nonlinear magneto-optical susceptibility in the superconducting state. Due to the surface sensitivity of the nonlinear optical response for systems with bulk inversion symmetry, we perform a group theoretical classification of t

M. S. Rzchowski

We investigate the nature of the phase transition in Josephson junctions arranged on a Kagome lattice. We find that an applied magnetic field corresponding to 1/2 flux quanta per elementary triangle results in a pi phase shift in the current phase relation for all bonds, resulting in an XY antiferromagnet. This corresponds to the order-from-disorder selected

Hideo Hasegawa

The temperature dependence of the giant magnetoresistance (GMR) for currents parallel and perpendicular to the multilayer plane, is discussed by taking account of the random exchange potentials, phonon scatterings and spin fluctuations. The effect of spin fluctuations, which plays an important role at finite temperatures, is included by means of the static f

N. S. Ananikian, S. K. Dallakian, N. Sh. Izmailian, K. A. Oganessyan

For the first time we present the consideration of the antiferromagnetic Ising model in case of fully developed chaos and obtain the exact connection between this model and chaotic repellers. We describe the chaotic properties of this statistical mechanical system via the invariants characterizing a fractal set and show that in chaotic region it displays pha

A. S. Mel&#39;nikov

The dynamics of 2D pancake vortices in Josephson-coupled superconducting/normal - metal multilayers is considered within the time-dependent Ginzburg-Landau theory. For temperatures close to $T_{c}$ a viscous drag force acting on a moving 2D vortex is shown to depend strongly on the conductivity of normal metal layers. For a tilted vortex line consisting of 2

Eric Sven Ristad

Consider the problem of multinomial estimation. You are given an alphabet of k distinct symbols and are told that the i-th symbol occurred exactly n_i times in the past. On the basis of this information alone, you must now estimate the conditional probability that the next symbol will be i. In this report, we present a new solution to this fundamental proble

HongSheng Zhao

A self-consistent stellar dynamical model for the Galactic bar is constructed from about 500 numerically computed orbits with an extension of the Schwarzschild technique. The model fits the {\sl COBE} found asymmetric boxy light distribution and the observed stellar kinematics of the bulge. The model potential is also consistent with the non-circular motions

T. Kundic, W. N. Colley, J. R. Gott, III

CCD photometry of the gravitational lens system 0957+561A,B in the g and r bands was obtained on alternate nights, weather permitting, from December 1994 through May 1995 using the Double Imaging Spectrograph (DIS) on the Apache Point Observatory (APO) 3.5-meter telescope. The remote observing and fast instrument change capabilities of this facility allowed

Glenn P. Tiede, Jay A. Frogel, D. M. Terndrup

We present deep near-IR photometry for Galactic bulge stars in Baade&#39;s Window, $(l,b) = (1.0°, -3.9°),$ and another minor axis field at $(l,b) = (0^\circ,-6^\circ)$. We combine our data with previously published photometry and construct a luminosity function over the range $5.5 \leq K_0 \leq 16.5$, deeper than any previously published. The slope of this

R. Fabbri, S. Torres

We perform the stastistics of temperature maxima and minima in COBE-DMR 2-year maps. For power-law spectra the surface distribution of peaks implies an amplitude consistent with more conventional analyses of COBE data (for instance, we get $Q_{\rm rms-PS}=17\pm 3\ μ$K for a spectral index $% n=1),$ but not with the measured quadrupole $Q_{\rm rms}=6\pm 3\ μ$

J. D&#39;Anna, A. Zee

We derive the connected correlation functions for eigenvalues of large Hermitian random matrices with independently distributed elements using both a diagrammatic and a renormalization group (RG) inspired approach. With the diagrammatic method we obtain a general form for the one, two and three-point connected Green function for this class of ensembles when

Remo Garattini

We calculate, in a class of Gauge invariant functionals, by variational methods, the difference of vacuum energy between two different backgrounds: Schwarzschild and Flat Space. We perform this evaluation in an Hamiltonian formulation of Quantum Gravity by standard &#39;&#39;$3+1$&#39;&#39; decomposition. After the decomposition the scalar curvature is expan

A. K. Ewing

We present results of a lattice analysis of the $B$ parameter, $B_B$, the decay constant $f_B$, and several mass splittings using the static approximation. Results were obtained for 60 quenched gauge configurations computed at $\beta=6.2$ on a lattice size of $24^3\times48$. Light quark propagators were calculated using the $O(a)$-improved Sheikholeslami-Woh

A. Hagberg, E. Meron, I. Rubinstein, B. Zaltzman

A high degree of control over the structure and dynamics of domain patterns in nonequilibrium systems can be achieved by applying nonuniform external fields near parity breaking front bifurcations. An external field with a linear spatial profile stabilizes a propagating front at a fixed position or induces oscillations with frequency that scales like the squ

Robert Baur, Res Urech

The electromagnetic corrections to the masses of the pseudoscalar mesons $\pi$ and $K$ are considered. We calculate in chiral perturbation theory the contributions which arise from resonances within a photon loop at order $O(e^2 m_q)$. Within this approach we find rather moderate deviations to Dashen's theorem.

K. Chamcham, M. A. Hendry

In this paper we analyse different chronometers based on the models of chemical evolution developed in Chamcham, Pitts \& Tayler (1993; hereafter CPT) and Chamcham \& Tayler (1994; hereafter CT). In those papers we discussed the ability of our models to reproduce the observed G-dwarf distribution in the solar neighbourhood, age-metallicity relation and radia

D. Pfenniger

Recent observational constraints restrict the strict applicability of stellar dynamics in spirals to a few rotation periods. However, stellar dynamics concepts such as periodic orbits are invaluable for understanding the various dynamical processes occurring during much more periods. A distinction of two instability types in stellar systems is pointed out, t

A. G. Bytsko, L. D. Faddeev

We study relations between the deformed cotangent bundle (T*B)_q for the Borel subgroup B of a given simple Lie group G, the quantum Lie algebra J_q associated with the corresponding quantum group G_q and the matrices generating Clebsch-Gordan coefficients (CGC) for J_q. We reveal the connection of these objects to quantum analogue of the model space M and q

Z. Kozioł, R. A. Dunlap

In many cases, the critical-state theory can be treated as a suffi ciently accurate approximation for the modelling of the magnetic properties of superconductors. In the present work, the magnetostrictive hysteresis is computed for a quite general case of the modified Kim-Anderson model. The results obtained reproduce many features of the giant magnetostrict

Z. Kozioł, R. A. Dunlap

The ac response of a slab of material with electrodynamic characteristics $E\sim j^{κ+1}$, $κ\geq0$, is studied numerically. From the solutions of the nonlinear diffusion equation, the fundamental and higher-order components of the harmonic susceptibility are obtained. A large portion of the data for every $κ$ can be scaled by a single parameter, $ξ$ =$t^{1/

Robert Bluhm, Alan Kostelecky

The revival structure and evolution of Rydberg wave packets are studied on a time scale much greater than the revival time $t_{\rm rev}$. We find a new level of revival structure and periodic motion different from that of the known fractional revivals. The new sequence of revivals culminates with the formation of a wave packet that more closely resembles the

Robert Bluhm, Alan Kostelecky

After a Rydberg wave packet forms, it is known to undergo a series of collapses and revivals within a time period called the revival time $t_{\rm rev}$, at the end of which it resembles its original shape. We study the behavior of Rydberg wave packets on time scales much greater than $t_{\rm rev}$. We find that after a few revival cycles the wave packet ceas

H. Kleinert, S. Thoms

For the anisotropic $[u (\sum_{i=1^N ϕ_i^2)^2+v \sum_{i=1^N ϕ_i^4]$-theory with {$N=2,3$} we calculate the imaginary parts of the renormalization-group functions in the form of a series expansion in $v$, i.e., around the isotropic case. Dimensional regularization is used to evaluate the fluctuation determinants for the isotropic instanton near the space dime

P. Maraner

The adiabatic motion of a charged, spinning, quantum particle in a two - dimensional magnetic field is studied. A suitable set of operators generalizing the cinematical momenta and the guiding center operators of a particle moving in a homogeneous magnetic field is constructed. This allows us to separate the two degrees of freedom of the system into a {\sl f