July 1997 arXiv papers — page 2

Jean Schneider

The Semiotic Interpretation (SI) of QM pushes further the Von Neumann point of view that `experience only makes statements of this type: an observer has made a certain observation; and never any like this: a physical quantity has a certain value.' The supposition that the observables of a system `possess' objective values is purely idealistic. Accord

W. Luecke, P. Nattermann

It is shown that, in order to avoid unacceptable nonlocal effects, the free parameters of the general Doebner-Goldin equation have to be chosen such that this nonlinear Schrödinger equation becomes Galilean covariant.

N. V. Vitanov, K. -A. Suominen

With radiofrequency fields one can control ultracold atoms in magnetic traps. These fields couple the atomic spin states, and are used in evaporative cooling which can lead to Bose-Einstein condensation in the atom cloud. Also, they can be used in controlled release of the condensate from the trap, thus providing output couplers for atom lasers. In this pape

S. L. Yakovlev, I. N. Filikhin

Scattering lengths for d-d, n-$^3$He and p-$^3$H systems are computed via Cluster Reduction Method for Yakubovsky equations in configuration space taking into account Coulomb interaction between protons. MT I-III potential model was used to describe the nucleon-nucleon interaction. Results of calculations are in a good agreement with existing experimental da

Charles W. Johnson, George Fai

An infinite system of nonlocal, individually confining solitons is considered as a model of high-density nuclear matter. The soliton-lattice problem is discussed in the Wigner-Seitz approximation. The cell size is varied to study the density dependence of physical quantities of interest. A transition to a system where quarks can migrate between solitons is f

P. Crochet, F. Rami, A. Gobbi, R. Dona

Using the FOPI detector at GSI Darmstadt, excitation functions of collective flow components were measured for the Au+Au system, in the reaction plane and out of this plane, at seven incident energies ranging from 100AMeV to 800AMeV. The threshold energies, corresponding to the onset of sideward-flow (balance energy) and squeeze-out effect (transition energy

Walter D. Neumann, Gadde A. Swarup

We describe a new approach to the canonical decompositions of 3-manifolds along tori and annuli due to Jaco-Shalen and Johannson (with ideas from Waldhausen) - the so-called JSJ-decomposition theorem. This approach gives an accessible proof of the decomposition theorem; in particular it does not use the annulus-torus theorems, and the theory of Seifert fibra

Franz-Viktor Kuhlmann

We give a criterion for a group homomorphism on a valued abelian group to be surjective and to preserve spherical completeness. We apply this to give a criterion for the existence of integration on a valued differential field. Further, we give a criterion for a sum of spherically complete subgroups of a valued abelian group to be spherically complete. This i

Robert M. Solovay

We show that the consistency strength of the system NFUB, a variant of Quine's "New Foundations" recently introduced by Randall Holmes, is precisely that of [ZFC - Power Set] + "There is a weakly compact cardinal''. This is a preliminary draft of the paper. Nevertheless, it contains a complete proof.

Andrei Losev, Gregory Moore, Samson L. Shatashvili

We consider M theory 5-branes with compact transverse dimensions. In certain limits the theory on the 5-brane decouples and defines ``little string theories'' in 5+1 dimensions. We show that the familiar structure of IIA/IIB,M,F- theory in 10,11,12 dimensions respectively has a perfect parallel in a theory of strings and membranes in 6,7,8 dimensions

Zurab Kakushadze

We briefly discuss the status of three-family grand unified string models.

M. Ishi-i, T. Kashiwa, N. Tanimura

Critical dynamics of the Nambu-Jona-Lasinio model, coupled to a constant electromagnetic field in D=2, 3, and 4, is reconsidered from a viewpoint of infrared behavior and vacuum instability. The latter is associated with constant electric fields and cannot be avoidable in the nonperturbative framework obtained through the proper time method. As for magnetic

Ph. Brax, J. Mourad

We consider open supermembranes in eleven dimensions in the presence of closed M-Theory five-branes. It has been shown that, in a flat space-time, the world-volume action is kappa invariant and preserves a fraction of the eleven dimensional supersymmetries if the boundaries of the membranes lie on the five-branes. We calculate the reparametrisation anomalies

Amihay Hanany, Matthew J. Strassler, Alberto Zaffaroni

We study aspects of confinement in the M theory fivebrane version of QCD (MQCD). We show heavy quarks are confined in hadrons (which take the form of membrane-fivebrane bound states) for N=1 and softly broken N=2 SU(Nc) MQCD. We explore and clarify the transition from the exotic physics of the latter to the standard physics of the former. In particular, the

S. Kumano

Flavor asymmetry in light antiquark distributions is discussed. In particular, recent progress on the u-bar/d-bar asymmetry is explained. Then, we discuss possible future experimental studies. 1. Introduction 2. Present situation 3. Future u-bar/d-bar asymmetry studies 3.1 Drell-Yan process 3.2 Charged-hadron production 3.3 W charge asymmetry 3.4 Deuteron ac

L. Lellouch, E. de Rafael, J. Taron

We derive lower bounds for the combination of light quark masses m_s +m_u and m_d +m_u. The derivation is based on first principles: the analyticity properties of two-point functions of local current operators and the positivity of the corresponding hadronic spectral functions. The bounds follow from the restriction of the sum over all possible hadronic stat

R. Akhoury, Paresh Malde, Robin G. Stuart

We provide a compendium of techniques that can be used to compute $O(N_fα^2)$ corrections to low-energy electroweak processes. Specifically, these are the 2-loop electroweak corrections containing a light fermion loop. It is shown that the vast majority of such corrections can be reduced to expressions involving a universal master integral for which an exact

J. R. Morris

An example of a supersymmetric model involving two interacting chiral superfields is presented here which allows for solutions describing string-like ``domain ribbon'' defects embedded within a domain wall. It is energetically favorable for the fermions within the wall to populate the domain ribbons, and an explicit solution is found for the fermion

R. N. Mohapatra

The supersymmetric left-right (SUSYLR) models solve several of the unnaturalness problems of the MSSM such as the R-parity and SUSY CP problems. If further the $W_R$ mass is in the TeV range, then it also provides a solution to the strong CP problem without the need for an axion. A crucial prediction of this model is the electric dipole moment of the neutron

Zoltan Gagyi-Palffy, Apostolos Pilaftsis, Karl Schilcher

The lepton-flavour-violating decay K_L --> e μis studied in detail within the context of SU(2)_R x SU(2)_L x U(1)_(B-L) models, which include heavy Majorana neutrinos. Particular attention is paid to the gauge independence of this decay process to one loop. In analogy with earlier studies on the K^0\bar{K}^0 mixing, it is explicitly shown how restoration of

J. Balla, M. V. Polyakov, C. Weiss

We compute the nucleon matrix elements of QCD operators of twist 3 and 4 in the instanton vacuum. We consider the operators determining 1/Q^2-power corrections to the Bjorken, Ellis-Jaffe and Gross-Llewellyn-Smith sum rules. The nucleon is described as a soliton of the effective chiral theory derived from instantons in the 1/N_c-expansion. QCD operators invo

D. V. Shirkov, A. V. Sidorov, S. V. Mikhailov

We consider the issue of an accurate description of the evolution of the non-singlet structure function moments $M_n(Q)$ near heavy quark threshold. To this aim we propose a simple modification of the standard massless \MSbar scheme approach to the next-to-leading QCD analysis of DIS data. We apply it to the processing of the modern CCFR'97 data for $xF_

Atsushi Yamada

Weak coupling expansion of a chiral gauge theory on a lattice is discussed in the overlap formulation. We analyze the fermion propagator and the fermion-fermion-gauge boson vertex in the one loop level. The chiral properties of the propagator and vertex are correctly preserved without tuning the parameters involved even after the one-loop renormalization, an

L. H. Ford

These lectures deal with selected aspects of quantum field theory in curved spacetime including the following topics: (1) Quantization of fields on a curved background, particle creation by gravitational fields, particle creation in an expanding universe; moving mirror radiation. (2) The Hawking effect - particle creation by black holes. (3) Ultraviolet and

Gerd Rudolph, Torsten Tok, Igor P. Volobuev

We present exact solutions in Einstein-Yang-Mills-Dirac theories with gauge groups SU(2) and SU(4) in Robertson-Walker space-time $R \times S^3 $, which are symmetric under the action of the group SO(4) of spatial rotations. Our approach is based on the dimensional reduction method for gauge and gravitational fields and relates symmetric solutions in EYMD th

E. Coccia, V. Fafone, G. Frossati, J. A. Lobo

The most important features of the proposed spherical gravitational wave detectors are closely linked with their symmetry. Hollow spheres share this property with solid ones, considered in the literature so far, and constitute an interesting alternative for the realization of an omnidirectional gravitational wave detector. In this paper we address the proble

Karl-Peter Marzlin, J"urgen Audretsch

We give a general treatment of the spontaneous excitation rates and the non-relativistic Lamb shift of constantly accelerated multi-level atoms as a model for multi-level detectors. Using a covariant formulation of the dipole coupling between the atom and the electromagnetic field we show that new Raman-like transitions can be induced by the acceleration. Un

Eckhard Meinrenken, Reyer Sjamaar

Consider a compact prequantizable symplectic manifold M on which a compact Lie group G acts in a Hamiltonian fashion. The ``quantization commutes with reduction'' theorem asserts that the G-invariant part of the equivariant index of M is equal to the Riemann-Roch number of the symplectic quotient of M, provided the quotient is nonsingular. We extend

Matthias Lesch, Jürgen Tolksdorf

We discuss the $ζ-$regularized determinant of elliptic boundary value problems on a line segment. Our framework is applicable for separated and non-separated boundary conditions.

Walter Kohn, Yigal Meir, Dmitrii E. Makarov

In principle, density functional theory yields the correct ground-state densities and energies of electronic systems under the action of a static external potential. However, traditional approximations fail to include Van der Waals energies between separated systems. This paper proposes a practical procedure for remedying this difficulty. Our method allows s

S. A. Kivelson, E. Fradkin, V. J. Emery

The character of the ground state of an antiferromagnetic insulator is fundamentally altered upon addition of even a small amount of charge. The added charges agglomerate along domain walls at which the spin correlations, which may or may not remain long-ranged, suffer a $π$ phase shift. In two dimensions, these domain walls are ``stripes'' which are

C. L. Henley

Jeong and Steinhardt (JS) implement local rules by selecting the sub-ensemble of tilings which have the maximum occurrences of a chosen pattern (``cluster'') C It is unknown how to prove that a given C implies a given sub-ensemble; counterexamples given here demonstrate this problem is nonlocal, and show the JS results depend on periodic boundary con

C. Jarzynski

It has recently been shown that the Helmholtz free energy difference between two equilibrium configurations of a system may be obtained from an ensemble of finite-time (nonequilibrium) measurements of the work performed in switching an external parameter of the system. Here this result is established, as an identity, within the master equation formalism. Exa

R. J. Radtke, S. Das Sarma, A. H. MacDonald

We examine the robustness of a recently predicted exchange-induced zero-field magnetic phase in semiconductor double quantum wells in which each well is spin-polarized and the polarization vectors are antiparallel. Magnetic instabilities are a general feature of Coulombic double quantum well systems at low densities. We argue that this antiferromagnetic phas

E. Timmermans, R. Cote

The dynamical structure of an atomic Bose-Einstein condensate limits the efficiency of the condensate in cooling slow impurity atoms. To illustrate the point, we show that an impurity atom moving in a homogeneous zero-temperature condensate is not scattered incoherently if its velocity is lower than the condensate sound velocity $c$, limiting cooling to velo

Eddy Timmermans, Paolo Tommasini

The essence of the Thomas-Fermi model is the assumption that the local behavior of a many-body system can be approximated by that of a homogeneous system. In this paper, we present the natural extension of the static Thomas-Fermi treatment of dilute Bose condensates, by describing the dynamical behavior of the condensate in the same quasi-homogeneous approxi

Eddy Timmermans, Paolo Tommasini

We present a single-scattering formalism for incoherent resonant light scattering by dilute quantum gas systems such as the atomic-trap Bose-Einstein condensates. We show that resonant scattering gives access to more information than the dynamical structure factor, familiar from non-resonant scattering. In particular, we show that the detuning dependence of

Ben Yu-Kuang Hu

The role of optical-phonons in frictional drag between two adjacent but electrically isolated two-dimensional electron gases is investigated. Since the optical-phonons in III-V materials have a considerably larger coupling to electrons than acoustic phonons (which are the dominant drag mechanism at low T and large separations) it might be expected that the o

Arthur K. Kerman, Paolo Tommasini

We investigate the Dirac time-dependent variational method using a Gaussian trial functional for an infinite one dimensional system of Bosons interacting through a repulsive contact interaction. The method produces a set of non-linear time dependent equations for the variational parameters. By solving the static equations we have calculated the ground state

Ronald Fisch

Monte Carlo simulations have been used to study a discretized Heisenberg ferromagnet (FM) in a random field on simple cubic lattices. The spin variable on each site is chosen from the twelve [110] directions. The random field has infinite strength and a random direction on a fraction x of the sites of the lattice, and is zero on the remaining sites. For x =

Anirvan M. Sengupta

I consider models with an impurity spin coupled to a fluctuating gaussian field with or without additional Kondo coupling of the conventional sort. In the case of isotropic fluctuations, the renormalisation group flows for these models have controlled fixed points when the autocorrelation of the gaussian field $h(t)$, $<T h(t) h(0)> \sim {1\over t^{2-ε}}$ wi

Arthur K. Kerman, Paolo Tommasini

We investigate the Dirac time-dependent variational method for a system of non-ideal Bosons interacting through an arbitrary two body potential. The method produces a set of non-linear time dependent equations for the variational parameters. In particular we have considered small oscillations about equilibrium. We obtain generalized RPA equations that can be

Sergei Nechaev

We consider the phase transition in the system of n simultaneously developing random walks on the halfline x>=0. All walks are independent on each others in all points except the origin x=0, where the point well is located. The well depth depends on the number of particles simultaneously staying at x=0. We consider the limit n>>1 and show that if the depth g

G. T. Barkema, U. Bastolla, P. Grassberger

Two closely related models of oriented self-avoiding walks (OSAWs) on a square lattice are studied. We use the pruned-enriched Rosenbluth method to determine numerically the phase diagram. Both models have three phases: a tight-spiral phase in which the binding of parallel steps dominates, a collapsed phase when the binding of anti-parallel steps dominates,

D. Goldhaber-Gordon, Hadas Shtrikman, D. Mahalu, David Abusch-Magder

The question of how localized electrons interact with delocalized electrons is central to many problems at the forefront of solid state physics. The simplest example is the Kondo phenomenon, which occurs when an impurity atom with an unpaired electron is placed in a metal, and the energy of the unpaired electron is far below the Fermi energy. At low temperat

T. H. Stoof, Yu. V. Nazarov

We have investigated the transport characteristics of an electron pump consisting of an asymmetric double quantum dot at zero bias voltage which is subject to electromagnetic radiation. Depending on the energies of the intermediate states in the pumping cycle, electrons can be transferred through the dots incoherently via sequential tunneling or coherently v

D. Errandonea, E. Moya

The effect of pressure on the low-frequency dielectric constant, $ε_0$, of single crystals of KNbO_3 is investigated by means of capacitance measurements. The dielectric constant increases with pressure up to 22.5 kbar, where it exhibits a large value ($ε_0$ = 5000), and then decreases. This change in its behaviour is related to a phase transition induced by

S. Mangioni, R. Deza, H. S. Wio, R. Toral

The model introduced by Van den Broeck, Parrondo and Toral [Phys. Rev. Lett.73, 3395 (1994)] -- leading to a second-order-like noise-induced nonequilibrium phase transition which shows reentrance as a function of the (multiplicative) noise intensity $σ$-- is investigated beyond the white-noise assumption. Through a Markovian approximation and within a mean-f

Hana Skoumalova

In this paper, a treatment of Czech phonological rules in two-level morphology approach is described. First the possible phonological alternations in Czech are listed and then their treatment in a practical application of a Czech morphological lexicon.

Stephen E. Zepf, Reinaldo R. de Carvalho, Andre L. B. Ribeiro

We study the luminosity function of galaxies in Hickson groups using our recent redshift survey of galaxies in and around 17 of these groups. We find that the galaxies in these regions have a luminosity function with M* = -19.5 + 5 log h, and alpha = -1.0, where M* and alpha are the usual parameters in the standard Schechter form of the luminosity function,

Mike. L. Balogh, Simon L. Morris, H. K. C. Yee, R. G. Carlberg

The rest frame equivalent width of the [OII]3727 emission line, W(OII), has been measured for cluster and field galaxies in the CNOC redshift survey of rich clusters at 0.2<z<0.55. Emission lines of any strength in cluster galaxies at all distances from the cluster centre, out to 2R_{200}, are less common than in field galaxies. The mean W(OII) in cluster ga

Ronald A. Remillard, Alan M. Levine

The RXTE All Sky Monitor provides a public database that includes more than one year of X-ray monitoring observations (2-12 keV) of X-ray binaries and a few active galactic nuclei. The instrument operates with a 40% duty cycle, and the exposures yield roughly 5 celestial scans per day. There have been 109 source detections, including 16 X-ray transients, the

P. N. Best, M. S. Longair, H. J. A. R&#34;ottgering

Hubble Space Telescope images are presented of a sample of 28 3CR radio galaxies with redshifts in the range 0.6 < z < 1.8, together with maps at comparable angular resolution of their radio structure, taken using the Very Large Array. Infrared images of the fields, taken with the United Kingdom InfraRed Telescope, are also presented. The optical images disp

Katherine M. Blundell, Steve Rawlings, Stephen A. Eales, Gregory B. Taylor

We describe the selection of a sample of 34 radio sources from the 6C survey (Hales, Baldwin & Warner 1993) from a region of sky covering 0.133 sr. The selection criteria for this sample, hereafter called 6C*, were chosen to optimise the chances of finding radio galaxies at redshift z > 4. Optical follow-up observations have already led to the discovery of t

J. Knoedlseder, K. Bennett, H. Bloemen, R. Diehl

We estimate the 1.8 MeV luminosity of the Sco-Cen association due to radioactive decay of 26Al to (4-15) 10e-5 ph cm**-2 s**-1. We propose a low surface brightness, limb brightened bubble for the 1.8 MeV intensity distribution. The detectibility of this distribution with existing gamma-ray telescopes is discussed.

R. Rutledge

Simulations of large-scale structure formation predict the formation of sheet- and filamentary structures, which are often invoked as the origin of the Lyman-alpha forest. In their simplest description, these sheets and filaments require a differential distribution of observed line-of-sight velocity widths ($b$) which will decrease as power-laws at velocitie

K. Glazebrook

Deep near-infrared (NIR) surveys are critical to our current, and even more to our future, understanding of galaxy evolution in the early universe. In this review I will be discussing the relevance of deep NIR surveys and looking at the information provided by different types of survey: broad-band imaging, spectroscopic observations and narrow-band imaging.

R. H. M. Schoenmakers, M. Franx, P. T. de Zeeuw

We present a method for measuring small deviations from axisymmetry of the potential of a filled gas disk. The method is based on a higher order harmonic expansion of the full velocity field of the disk. This expansion is made by first fitting a tilted-ring model to the velocity field of the gas disk and subsequently expanding the velocity field along each r

T. Shahbaz, J. Casares, P. A. Charles

We have obtained medium resolution spectra of the neutron star X-ray transient Aql X-1 during quiescence. We determine the spectral type of the companion star to be K1 and also estimate its rotation speed to be 62(+30 -20) kms-1. By measuring the width of the Halpha emission line profile of the accretion disc, we estimate the binary inclination to about 50 d

Wolfgang P. Gieren, Pascal Fouque, Matias Gomez

We have obtained the radii and distances of 16 galactic Cepheids supposed to be members in open clusters or associations using the new optical and near-infrared calibrations of the surface brightness (Barnes-Evans) method given by Fouque & Gieren (1997). We discuss in detail possible systematic errors in our infrared solutions and conclude that the typical t

Percy L. Gomez, Michael J. Ledlow, Jack O. Burns, Jason Pinkney

We present the results of our multiwavelength study of two nearby Abell clusters that contain extended tailed radio sources. From our analysis of PSPC X-ray, VLA radio, and optical data, we find strong evidence that these clusters are not relaxed. Significant X-ray substructure is revealed by examining their X-ray surface brightness maps. We report 130 new r

Sergei Skorik

We study the partition functions of quantum impurity problems in the domain of complex applied bias for its relation to the non-equilibrium current suggested by Fendley, Lesage and Saleur (cond-mat/9510055). The problem is reformulated as a certain generalization of the linear response theory that accomodates an additional complex variable. It is shown that

E. Keith, Ernest Ma, D. P. Roy

In the Higgs sector of the Minimal Supersymmetric Standard Model, the mass of the pseudoscalar $A$ is an independent parameter together with $\tan \beta \equiv v_2/v_1$. If $m_A$ is small, then the process $e^+ e^- \to h + A$ is kinematically allowed and is suppressed only if $\tan \beta$ is small. On the other hand, the mass of the charged Higgs boson is no

John P. Ralston, Pankaj Jain, Borge Nodland

We discuss a new mechanism which could cause a rotation of polarization of electromagnetic waves due to magnetic fields on cosmological scales. The effect is due to the geometrical phase of Pancharatnam and Berry, and causes a corkscrew twisting of the plane of polarization. The new effect represents an additional tool that allows possible intergalactic and

F. de Campos, M. C. Gonzalez-Garcia, S. F. Novaes

We estimate the attainable limits on the coefficients of dimension--6 operators from the analysis of Higgs boson phenomenology, in the framework of a $SU_L(2) \times U_Y(1)$ gauge-invariant effective Lagrangian. Our results, based on the data sample already collected by the collaborations at Fermilab Tevatron, show that the coefficients of Higgs-vector boson

D. Kilin, M. Schreiber

The linear and quadratic interactions of an impurity vibrational mode coupled with a heat bath are investigated with a non-Markovian equation of motion for the reduced density matrix valid for the initial, intermediate and kinetic stages of relaxation. The evolution of the superpositional states is considered for all cases.

S. Bauberger, G. Weiglein

The Higgs-mass dependence of the Standard Model contributions to the correlation between the gauge-boson masses is studied at the two-loop level. Exact results are given for the Higgs-dependent two-loop corrections associated with the fermions, i.e. no expansion in the top-quark and the Higgs-boson mass is made. The results for the top quark are compared wit

James B. Dove, Jorn Wilms, Michael A. Nowak, Brian A. Vaughan

We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200 keV, using data from a 10 ksec observation by the Rossi X-ray Timing Explorer. The spectrum can be well described phenomenologically by an exponentially cut-off power law with a photon index Gamma = 1.45 +/- 0.02 (a value considerably harder than typically found),

J. G. Russo

A natural SL(2,Z) invariant generalization of the Veneziano amplitude in type IIB superstring theory is investigated. It includes certain perturbative and non-perturbative (D-instanton) contributions, and it reduces to the correct expressions in different limits. The singularities are poles in the $s$-$t$-$u$ channels, corresponding to the exchange of partic

S. N. Zhang, I. F. Mirabel, B. A. Harmon, R. A. Kroeger

We review the recent multifrequency studies of galactic black hole binaries, aiming at revealing the underlying emission processes and physical properties in these systems. The optical and infrared observations are important for determining their system parameters, such as the companion star type, orbital period and separation, inclination angle and the blac

S. Bellucci, V. Gribanov, E. Ivanov, S. Krivonos

We propose a simple method for constructing representations of (super)conformal and nonlinear W-type algebras in terms of their subalgebras and corresponding Nambu-Goldstone fields. We apply it to N=2 and N=1 superconformal algebras and describe in this way various embeddings of strings and superstrings for which these algebras and their subalgebras define w

M. Benayoun, S. Eidelman, K. Maltman, H. B. O&#39;Connell

We compare the predictions of a range of existing models based on the Vector Meson Dominance hypothesis with data on e^+ e^- -> pi^+ pi^$ and e^+ e^- -> mu^+ mu^- cross-sections and the phase and near-threshold behavior of the timelike pion form factor, with the aim of determining which (if any) of these models is capable of providing an accurate representat

Djamel Dou, Roberto Percacci

We compute the running of the cosmological constant and Newton&#39;s constant taking into account the effect of quantum fields with any spin between 0 and 2. We find that Newton&#39;s constant does not vary appreciably but the cosmological constant can change by many orders of magnitude when one goes from cosmological scales to typical elementary particle sc

George Chiladze, Adam F. Falk

The CLEO Collaboration recently has announced the discovery of an excited charmed and strange baryon. We estimate the expected width of this new member of the Xi_c family. We discuss the phenomenology of the excited csq and css states, and consider what additional charmed baryons might be observable in the future. We point out that the final state Xi_c + K c

J. Avan, L. Frappat, M. Rossi, P. Sorba

It is shown that the elliptic algebra ${\cal A}_{q,p}(\hat{sl}(2)_c)$ at the critical level c=-2 has a multidimensional center containing some trace-like operators t(z). A family of Poisson structures indexed by a non-negative integer and containing the q-deformed Virasoro algebra is constructed on this center. We show also that t(z) close an exchange algebr

Hong-An Peng, Jia-Sheng Xu

Motivated by the recent experimental data about candidates for glueball from different processes, we discuss in this paper the production of 0^{++} glueball from double diffractive scattering at momentum transfer |t|< 1GeV^2 in high energy p+p(\bar p) collision. We apply the phenomenology of Pomeron (IP) of Donnachie-Landshoff, the field theory model of IP o

J. Guerrero, M. Calixto, V. Aldaya

The implementation of modular invariance on the torus as a phase space at the quantum level is discussed in a group-theoretical framework. Unlike the classical case, at the quantum level some restrictions on the parameters of the theory should be imposed to ensure modular invariance. Two cases must be considered, depending on the cohomology class of the symp

Karl-Peter Marzlin, Weiping Zhang

In this letter, atom optic techniques are proposed to control the excitation of a Bose-Einstein condensate in an atomic trap. We show that by employing the dipole potential induced by four highly detuned travelling-wave laser beams with appropriate phases and frequencies, one can coherently excite a trapped Bose-Einstein condensate composed of ultracold alka

Jae Hyung Yee

The functional Schrodinger picture formulation of quantum field theory and the variational Gaussian approximation method based on the formulation are briefly reviewed. After presenting recent attempts to improve the variational approximation, we introduce a new systematic method based on the background field method, which enables one to compute the order-by-

Masahide Yamaguchi, Jun&#39;ichi Yokoyama

We investigate whether the universe was homogeneously in the false vacuum state at the critical temperature of a weakly first-order phase transition such as the electroweak phase transition in terms of a series of numerical simulations of a phenomenological Langevin equation, whose noise term is derived from the effective action but the dissipative term is s

Masashi Wakamatsu, Takanori Kubota

The isospin asymmetry of the sea quark distribution as well as the unexpectedly small quark spin fraction of the nucleon are two outstanding discoveries recently made in the physics of deep-inelastic structure functions. We evaluate here the corresponding quark distribution functions within the framework of the chiral quark soliton model, which is an effecti

Paolo Casati, Gregorio Falqui, Franco Magri, Marco Pedroni

We discuss the geometry of the Marsden-Ratiu reduction theorem for a bihamiltonian manifold. We consider the case of the manifolds associated with the Gel&#39;fand-Dickey theory, i.e., loop algebras over sl(n+1). We provide an explicit identification, tailored on the MR reduction, of the Adler-Gel&#39;fand-Dickey brackets with the Poisson brackets on the MR-

A. S. Cârstea, D. Grecu, A. Visinescu

One dimensional nonlinear lattices with harmonic long range interaction potentials (LRIP) having an inverse power kernel type, are studied. For the nearest neighbour nonlinear interaction we consider the anharmonic potential of the Fermi-Pasta-Ulam problem and the ϕ^3+ϕ^4 potential as well. The continuum limit is obtained following the method used by Ishimor

Jim McElwaine

This dissertation investigates questions arising in the consistent histories formulation of the quantum mechanics of closed systems. Various criteria for approximate consistency are analysed. The connection between the Dowker-Halliwell criterion and sphere packing problems is shown and used to prove several new bounds on the violation of probability sum rule

G. Berginc, C. Bourrely, C. Ordenovic, B. Torresani

We study the electromagnetic scattering by multilayered biperiodic aggregates of dielectric layers and gratings of conducting plates. We show that the characteristic lengths of such structures provide a good control of absorption bands. The influence of the physical parameters of the problem (sizes, impedances) is discussed.

Aric Hagberg, Ehud Meron

Kinematic equations for the motion of slowly propagating, weakly curved fronts in bistable media are derived. The equations generalize earlier derivations where algebraic relations between the normal front velocity and its curvature are assumed. Such relations do not capture the dynamics near nonequilibrium Ising-Bloch (NIB) bifurcations, where transitions b

St. Hollinger, M. Luecke

Spatially extended stationary and traveling states in the strongly nonlinear regime of convection in layers of binary fluid mixtures heated from below are described by a few-mode-model. It is derived from the proper hydrodynamic balance equations including experimentally relevant boundary conditions with a non-standard Galerkin approximation that uses numeri

K. Langanke, P. Vogel, Dao-Chen Zheng

We perform Shell Model Monte Carlo calculations of selected N=Z pf-shell nuclei with a schematic hamiltonian containing isovector pairing and quadrupole-quadrupole interactions. Compared to realistic interactions, this hamiltonian does not give rise to the SMMC ``sign problem&#39;&#39;, while at the same time resembles essential features of the realistic int

P. B. Radha, D. J. Dean, S. E. Koonin, K. Langanke

We use the shell model Monte Carlo method to calculate complete 0f1p-shell response functions for Gamow-Teller (GT) operators and obtain the corresponding strength distributions using a Maximum Entropy technique. The approach is validated against direct diagonalization for 48Ti. Calculated GT strength distributions agree well with data from (n,p) and (p,n) r

G. W. Carter, P. J. Ellis

We study the finite temperature properties of an effective chiral Lagrangian which describes nuclear matter. Thermal fluctuations in both the nucleon and the meson fields are considered. The logarithmic and square root terms in the effective potential are evaluated by expansion and resummation with the result written in terms of the exponential integral and

R. Beck, H. P. Krahn

We reply to the Comment of A.M. Sandorfi et al. [nucl-th/9707028] on the E2/M1 ratio from the Mainz photoproduction data, nucl-th/9707028 v2. We support our published result for the E2/M1 ratio of REM = -(2.5 +- 0.2 +- 0.2)%.

Bing Han

This is essentially the author&#39;s thesis submited to The University of Chicago (May 1997). I prove the validity of Tamagawa number conjecture of Bloch-Kato for certain Hecke characters. I study the exponential map and local Tamagawa number for all odd primes (both ordinary and supersingular), using Kato&#39;s explicit reciprocity law for one dimensional L

Christine Bessenrodt, Jørn B. Olsson

Jantzen-Seitz partitions are those $p$-regular partitions of~$n$ which label $p$-modular irreducible representations of the symmetric group $S_n$ which remain irreducible when restricted to $S_{n-1}$; they have recently also been found to be important for certain exactly solvable models in statistical mechanics. In this article we study their combinatorial p

B. Andreas

We study a class of four dimensional, anisotropic string backgrounds and analyse their expansion and singularity structure. In particular we will see how O(3,3) duality acts on this class.

Nathan Berkovits

In these proceedings for the First School on Field Theory and Gravitation (Vitória, Brasil), a brief introduction is given to superstring theory and its duality symmetries. This introduction is intended for beginning graduate students with no prior knowledge of string theory.

N. Dragon, H. Guenther, U. Theis

We show that there is no off-shell Palatini formulation of minimal supergravity. Nonetheless, we have been able to generalize the multiplet and Lagrangians of this theory to the case of vanishing determinant of the vierbein. Unfortunately, the requirement of regularity does not single out a unique action.

Gianguido Dall&#39;Agata, Kurt Lechner

In this paper we present a superspace formulation of $N = 1, D = 6$ supergravity with one tensor-multiplet and an arbitrary number of vector- and hypermultiplets, in which the bosonic abelian superforms of the theory, the dilaton, the abelian gauge fields and the two-form are replaced by their S-duals i.e. four, three and two-superforms respectively, in comp

E Corrigan

The sinh-Gordon model with integrable boundary conditions is considered in low order perturbation theory. It is pointed out that results obtained by Ghoshal for the sine-Gordon breather reflection factors suggest an interesting dual relationship between models with different boundary conditions. Ghoshal&#39;s formula for the lightest breather is checked pert

Chris Quigg

I survey the characteristics of hadron colliders as tools to investigate top-quark physics and to explore the 1-TeV scale of electroweak symmetry breaking.

Yoshio Koide

Neutrino masses and mixings are investigated on the basis of a universal seesaw mass matrix model, in which quark (except for top) and charged lepton mass matrices M_f and neutrino mass matrix M_νare given by M_f \simeq m_L M_F^{-1} m_R and M_ν\simeq m_L M_F^{-1} m_L^T (F=N), respectively. For a simple model which can successfully describe quark masses and m