March 1996 arXiv papers — page 10

Kenneth Holmlund

We have studied the dynamics of flux-lines in an impure two-dimensional superconductor using numerical Brownian dynamics. In the dirty pinning limit and for small center-of-mass velocities the flux lines prefer traveling in narrow channels uniquely determined by the pinning configuration. At a certain critical drag force there is a dynamic transition from th

J. Dukelsky, V. A. Khodel, P. Schuck, V. R. Shaginyan

The phenomenon of the so called Fermion condensation, a phase transition analogous to Bose condensation but for Fermions, postulated in the past to occur in systems with strong momentum dependent forces, is reanalysed in a model with infinite range interactions. The strongly non Fermi Liquid behavior of this system is demonstrated analytically at $T=0$ and a

S. Grabowski, J. Schmalian, M. Langer, K. H. Bennemann

The normal and the superconducting state of two coupled CuO_2 layers in the High-T_c superconductors are investigated by using the bilayer Hubbard model, the FLEX approximation on the real frequency axis and the Eliashberg theory. We find that the planes are antiferromagnetically correlated which leads to a strongly enhanced shadow band formation. Furthermor

Burkhard Schmidt, Peter Thalmeier, Peter Fulde

An explanation is given for the observed magnetic-field dependence of the low-temperature specific heat coefficient of Yb(4)As(3). It is based on a recently developed model for that material which can explain the observed heavy-fermion behaviour. According to it the Yb(3+)-ions are positioned in a net of parallel chains with an effective spin coupling of the

James Theiler, Dean Prichard

We compare two theoretically distinct approaches to generating artificial (or ``surrogate'') data for testing hypotheses about a given data set. The first and more straightforward approach is to fit a single ``best'' model to the original data, and then to generate surrogate data sets that are ``typical realizations'' of that model. T

Fernando C. N. Pereira, Rebecca N. Wright

Phrase-structure grammars are effective models for important syntactic and semantic aspects of natural languages, but can be computationally too demanding for use as language models in real-time speech recognition. Therefore, finite-state models are used instead, even though they lack expressive power. To reconcile those two alternatives, we designed an algo

Uros Seljak, Matias Zaldarriaga

We present a new method for calculating linear cosmic microwave background (CMB) anisotropy spectra based on integration over sources along the photon past light cone. In this approach the temperature anisotropy is written as a time integral over the product of a geometrical term and a source term. The geometrical term is given by radial eigenfunctions which

B. T. Draine, Frank Bertoldi

The structure of stationary photodissociation fronts is revisited. H_2 self- shielding is discussed, including the effects of line overlap. We find that line overlap is important for N(H_2) > 10^{20} cm^{-2}. We compute multiline UV pumping models, and compare these with simple analytic approximations for the effects of self-shielding. The overall fluorescen

J. A. Peacock, S. J. Dodds

Hamilton et al. have suggested an invaluable scaling formula which describes how the power spectra of density fluctuations evolve into the nonlinear regime of hierarchical clustering. This paper presents an extension of their method to low-density universes and universes with nonzero cosmological constant. We pay particular attention to models with large neg

D. R. Phillips, S. J. Wallace

Firstly, a systematic procedure is derived for obtaining three-dimensional bound-state equations from four-dimensional ones. Unlike ``quasi-potential approaches'' this procedure does not involve the use of delta-function constraints on the relative four-momentum. In the absence of negative-energy states, the kernels of the three-dimensional equations

Scott Chapman, J. Rayford Nix

We present a realistic expanding source model with nine parameters that are necessary and sufficient to describe the main physics occuring during hydrodynamical freezeout of the excited hadronic matter produced in relativistic heavy-ion collisions. As a first test of the model, we compare it to data from central Si + Au collisions at p_lab/A = 14.6 GeV/c mea

B. Normand, T. M. Rice

The recently-discovered ``ladder'' compound LaCuO$_{2.5}$ has been found to admit hole doping without altering its structure of coupled copper oxide ladders. While susceptibility measurements on the parent compound suggest a spin gap and a spin-liquid state, NMR results indicate magnetic order at low temperatures. These seemingly contradictory result

Alexander Nazarenko, Stephan Haas, Jose Riera, Adriana Moreo

Recently proposed scenarios for the cuprates make extensive use of a ``flat'' quasiparticle (q.p.) dispersion and short-range hole-hole interactions in real-space, both caused by antiferromagnetic (AF) correlations. The density of states (DOS) at half-filling has a robust peak which boosts the superconducting critical temperature $T_c$ to large value

Ulrich Bunke, Martin Olbrich

We prove Patterson's conjecture about the singularities of the Selberg zeta function associated to a convex-cocompact, torsion free group acting on a hyperbolic space.

Alessandro Vespignani, Stefano Zapperi, Vittorio Loreto

We present a detailed discussion of a novel dynamical renormalization group scheme: the Dynamically Driven Renormalization Group (DDRG). This is a general renormalization method developed for dynamical systems with non-equilibrium critical steady-state. The method is based on a real space renormalization scheme driven by a dynamical steady-state condition wh

Dan Edidin, William Graham

In this paper we develop an equivariant intersection theory for actions of algebraic groups on algebraic schemes. The theory is based on our construction of equivariant Chow groups. They are algebraic analogues of equivariant cohomology groups which satsify the formal properties of ordinary Chow groups. In addition, they enjoy many of the properties of equiv

Rainer Kayser, Phillip Helbig, Thomas Schramm

The calculation of distances is of fundamental importance in extragalactic astronomy and cosmology. However, no practical implementation for the general case has previously been available. We derive a second-order differential equation for the angular size distance valid not only in all em homogeneous Friedmann-Lemaitre cosmological models, parametrised by $

M. J. Duff, H. Lu, C. N. Pope

Heterotic strings on $R^6 \times K3$ generically appear to undergo some interesting new phase transition at that value of the string coupling for which the one of the six-dimensional gauge field kinetic energies changes sign. An exception is the $E_8 \times E_8$ string with equal instanton numbers in the two $E_8$'s, which admits a heterotic/heterotic se

Richard Cleve, David P. DiVincenzo

An explicit algorithm for performing Schumacher's noiseless compression of quantum bits is given. This algorithm is based on a combinatorial expression for a particular bijection among binary strings. The algorithm, which adheres to the rules of reversible programming, is expressed in a high-level pseudocode language. It is implemented using $O(n^3)$ two

Max Tegmark

At first sight, an accurate description of the state of the universe appears to require a mind-bogglingly large and perhaps even infinite amount of information, even if we restrict our attention to a small subsystem such as a rabbit. In this paper, it is suggested that most of this information is merely apparent, as seen from our subjective viewpoints, and t

Marek Gaździcki, Ulrich Heinz

We argue that the recent analysis of strangeness production in nuclear collisions at 200 $A$ GeV/$c$ performed by Topor Pop {\it et al.} \cite{To:95} is flawed. The conclusions are based on an erroneous interpretation of the data and the numerical model results. The term ``strangeness enhancement" is used in a misleading way.

P. C. Argyres, M. R. Plesser, N. Seiberg

We analyze in detail the moduli space of vacua of N=2 SUSY QCD with n_c colors and n_f flavors. The Coulomb branch has submanifolds with non-Abelian gauge symmetry. The massless quarks and gluons at these vacua are smoothly connected to the underlying elementary quarks and gluons. Upon breaking N=2 by an N=1 preserving mass term for the adjoint field the the

Juan P. Garrahan, Martin Kruczenski, Daniel R. Bes

The Becchi-Rouet-Stora-Tyutin (BRST) treatment for the quantization of collective coordinates is considered in the Lagrangian formalism. The motion of a particle in a Riemannian manifold is studied in the case when the classical solutions break a non-abelian global invariance of the action. Collective coordinates are introduced, and the resulting gauge theor

Niclas Wyllard

We reconsider the, by Brink and Vasiliev, recently proposed generalized Toda field theories using the framework of WZNW$\rightarrow$Toda reduction. The reduced theory has a gauge symmetry which can be fixed in various ways. We discuss some different gauge choices. In particular we study the ${\cal W}$ algebra associated with the generalized model in some dif

V. Karimipour

We extend our previous analysis of the classical integrable models of Calogero in several respects. Firstly we provide the algebraic resaons of their quantum integrability.Secondly we show why these systems allow their initial value problem to be solved in closed form . Furthermore we show that due to their similarity with the above models the classical and

Hiroshi Shirokura

I review my new method for solving general 1-matrix models by expanding in $N^{-1}$ without taking a physical continuum limit. Using my method, each coefficient of the free energy in the genus expansion is exactly computable. One can include physical information in a function which is uniquely specified by the action of the model. My method gives completely

Hung Cheng, S. P. Li

By using the Ward-Takahashi identities in the Landau gauge, we derive exact relations between particle masses and the vacuum expectation value of the Higgs field in the Abelian gauge field theory with a Higgs meson.

I. Martin, A. Restuccia

An explicit canonical construction of monopole connections on non trivial U(1) bundles over Riemann surfaces of any genus is given. The class of monopole solutions depend on the conformal class of the given Riemann surface and a set of integer weights. The reduction of Seiberg-Witten 4-monopole equations to Riemann surfaces is performed. It is shown then tha

A. Harindranath, Wei-Min Zhang

In this paper we study the matrix element of the transverse component of the bilocal vector current in the context of deep inelastic scattering. BJL limit of high energy amplitudes together with light-front current algebra imply the same parton interpretation for its matrix element as that of the plus component. On the other hand, the transverse component de

S. Jadach, M. Melles, B. F. L. Ward, S. A. Yost

We present the exact O(alpha) correction to the process e+ e- -> e+ e- + gamma in the low angle luminosity regime at SLC/LEP energies. We give explicit formulas for the completely differential cross section. As an important application, we illustrate the size of the respective corrections of O(alpha^2) to the SLC/LEP luminosity cross section. We show explici

T. Han, K. Whisnant, B. -L. Young, X. Zhang

We determine the constraints on the anomalous top-quark coupling associated with the flavor-changing neutral current vertex $\bar t c γ$ from the limits on the $b$-quark rare decay $b\rightarrow s γ$ and non-standard top-quark decays. Based on these constraints, we discuss the experimental observability of the rare decay mode $t \rightarrow c γ$, both at the

Andrei L. Kataev, Victor T. Kim

The brief discussion of the studies of the radiative QCD corrections to the decay widths and branching ratios of the Standard Model Higgs boson with the mass 2 m_b < M_H < 2 M_W is given. The numerical results are obtained with the help of our FORTRAN code SEEHIGGS.

M. Kacir, I. Zahed

The partition function of two-dimensional solitons in a heat bath of mesons is worked out to one-loop. For temperatures large compared to the meson mass, the free energy is dominated by the meson-soliton bound states and the zero modes, a consequence of Levinson&#39;s theorem. Using the Bethe-Uhlenbeck formula we compare the soliton energy-shift to the shift

Yuval Grossman

The Standard Model predicts a large width difference in the $B_s$ system. New physics can contribute significantly to the {\it mass} difference. If this contribution is CP violating, this will always result in a reduction of the {\it width} difference. The analyses of measurements of the width difference using $B_s$ decays into CP eigenstates have to be modi

Frank Cuypers

We review the selectron production mechanisms in the linear collider modes which do not require positrons. The standard model backgrounds can be rendered harmless or even be nearly eliminated with polarized beams. We insist on the complementarity of these different experiments.

J. Belz

We have searched for a neutral $H$ dibaryon decaying via $H\toΛn$ and $H\toΣ^0 n$. Our search has yielded two candidate events from which we set an upper limit on the $H$ production cross section. Normalizing to the inclusive $Λ$ production cross section, we find $(dσ_H/dΩ) / (dσ_Λ/dΩ) < 6.3\times 10^{-6}$ at 90% C.L., for an $H$ of mass $\approx$ 2.15 GeV/$

V. D. Dzhunushaliev

The solution of the 5D Kaluza-Klein&#39;s theory is obtained. This solution is a Lorentzian wormhole between two event horizons. It is shown that this solution can sew with (4D Reissner-Nordström&#39;s solution + Maxwell&#39;s electrical field) on the event horizon. Such construction is composite wormhole connecting two asymptotically flat region. From the v

R. Pnini, B. Shapiro

We consider the intensity pattern, generated by a monochromatic source, in a disordered cavity coupled to the environment. For weak coupling, and when the source frequency is tuned to a resonance, the intensity distribution is close to Porter-Thomas distribution. When the coupling increases, gradually crosses over to the Rayleigh distribution. The joint prob

G. M. Kavoulakis, Gordon Baym

We study the non-radiative Auger decay of excitons in Cu$_2$O, in which two excitons scatter to an excited electron and hole. The exciton decay rate for the direct and the phonon-assisted processes is calculated from first principles; incorporating the band structure of the material leads to a relatively shorter lifetime of the triplet state ortho excitons.

M. J. Rozenberg, I. H. Inoue, H. Makino, F. Iga

We study the photoemission and optical conductivity response of the strongly correlated metallic system $Ca_xSr_{1-x}VO_3$. We find that the basic features of the transfer of spectral weight in photoemission experiments and the unusual lineshape of the optical response can be understood by modeling the system with a one band Hubbard model close to the Mott-H

A. J. Gill, T. W. B. Kibble

Motivated by the study of cosmological phase transitions, our understanding of the formation of topological defects during spontaneous symmetry-breaking and the associated non-equilibrium field theory has recently changed. Experiments have been performed in superfluid $^4$He to test the new ideas involved. In particular, it has been observed that a vortex de

Madan Rao, Surajit Sengupta

Martensites are metastable phases, possessing a characteristic morphology, usually formed during a fast quench accross a structural transition. We attempt to understand these morphological features using a coarsegrained free energy functional ${\cal F}[ε; Φ]$ which contains, in addition to the usual strain fields $ε_{ij}$ (the `` order parameter&#39;&#39; fo

Attila Szolnoki, Tibor Antal, Gyorgy Szabo

The homogeneous ordered state transforms into a polydomain state via a nucleation mechanism in two-dimensional lattice gas if the particle jumps are biased by an external field $E$. A simple phenomenological model is used to describe the time evolution of a circular interface separating the ordered regions. It is shown that the area of a domain increases if

Safi R. Bahcall

Apparently conflicting phase-sensitive measurements of the order parameter symmetry in the high-T$_c$ superconductors may be explained by regions near surfaces in which the order parameter symmetry is different than in the bulk. These surface states can lead to interesting and testable effects.

Fernando C. N. Pereira, Michael D. Riley

We present a general framework based on weighted finite automata and weighted finite-state transducers for describing and implementing speech recognizers. The framework allows us to represent uniformly the information sources and data structures used in recognition, including context-dependent units, pronunciation dictionaries, language models and lattices.

G. Lamer, H. Brunner, R. Staubert

We present soft X-ray spectra of 74 BL Lacertae objects observed with the PSPC detector on board of the ROSAT satellite. The sample contains all BL Lac objects detected during the pointed observation phase as a target or serendipitously. We have investigated the soft X-ray and broad band spectral properties and discuss the consequences for the X-ray emission

Marijn Franx, Pieter van Dokkum

The existence of the Fundamental Plane of early-type galaxies implies that the M/L ratios of early-types are well behaved. It provides therefore an important tool to measure the evolution of the M/L ratio with redshift. These measurements, in combination with measurements of the evolution of the luminosity function, can be used to constrain the mass evolutio

Harald Skarke

According to a recently proposed scheme for the classification of reflexive polyhedra, weight systems of a certain type play a prominent role. These weight systems are classified for the cases $n=3$ and $n=4$, corresponding to toric varieties with K3 and Calabi--Yau hypersurfaces, respectively. For $n=3$ we find the well known 95 weight systems corresponding

F. Lesage, H. Saleur, S. Skorik

We show how to compute analytically time and space dependent correlations in one dimensional quantum integrable systems with an impurity. Our approach is based on a description of these systems in terms of massless scattering of quasiparticles. Correlators follow then from matrix elements of local operators between multiparticle states, the ``massless form f

Markus A. Luty, Martin Schmaltz, John Terning

We consider supersymmetric Sp(2N) gauge theories with F matter fields in the defining representation, one matter field in the adjoint representation, and no superpotential. We construct a sequence of dual descriptions of this theory using the dualities of Seiberg combined with the ``deconfinement&#39;&#39; method introduced by Berkooz. Our duals hint at a ne

Erich Holtmann, Masahiro Kawasaki, Takeo Moroi

We discuss a new mechanism which can solve the crisis in standard big-bang nucleosynthesis. A long-lived particle $X$ ($10^4 sec \lesssim τ_X \lesssim 10^6 sec$) which decays into photon(s) will induce cascade photons, and destroy significant amounts of D and $^3$He without destroying $^4$He or too much $^7$Li. We numerically investigate this process and der

I. L. Grach, I. M. Narodetskii, S. Simula, K. A. Ter-Martirosyan

A relativistic quark model is applied to the description of semileptonic and non-leptonic charmed decays of the B-meson. The exclusive semileptonic modes B -> D l νand B -> D* l νare described through the universal Isgur-Wise form factor, which is calculated in terms of a constituent quark model wave function for the B-meson. Different approximations for the

J. Delorme, G. Chanfray, M. Ericson

We study the evolution with density of the quark condensate in the nuclear medium with interacting nucleons and including the short range correlations. We work with two chiral models, the linear sigma model and the non-linear one. For the last one we use two versions, one which does not satisfy PCAC, and another one which does. We show that the quark condens

Max Tegmark, Andy Taylor, Alan Heavens

Since cosmology is no longer "the data-starved science", the problem of how to best analyze large data sets has recently received considerable attention, and Karhunen-Loeve eigenvalue methods have been applied to both galaxy redshift surveys and Cosmic Microwave Background (CMB) maps. We present a comprehensive discussion of methods for estimating cosmologic

Hung cheng, S. P. Li

We calculate the triangular anomaly in the next order in the Abelian-Higgs theory with an appropriate number of families of chiral fermions and with Yukawa couplings. The calculation is performed with the method of subtraction aided by the Ward- Takahashi identities. This anomaly amplitude is performed without any regularization and is found to vanish.

Wesley N. Colley, James E. Rhoads, Jeremiah P. Ostriker, David N. Spergel

We compute the two-point angular correlation function and number-magnitude relation of Hubble Deep Field sources in order to assess their nature. We find that the correlation peaks between 0.25 arcsec and 0.4 arcsec with amplitude of 2 or greater, and much more for the smallest objects. This angular scale corresponds to physical scales of order 1 kpc for red

E. I. Rashba, L. E. Zhukov, A. L. Efros

We prove the existence of a set of two-scale magnetic Wannier orbitals w_{m,n}(r) on the infinite plane. The quantum numbers of these states are the positions {m,n} of their centers which form a von Neumann lattice. Function w_{00}localized at the origin has a nearly Gaussian shape of exp(-r^2/4l^2)/sqrt(2Pi) for r < sqrt(2Pi)l,where l is the magnetic length

S. A. Gurvitz

We study noninvasive measurement of stationary currents in mesoscopic systems. It is shown that the measurement process is fully described by the Schrödinger equation without any additional reduction postulate and without the introduction of an observer. Nevertheless the possibility of observing a particular state out of coherent superposition leads to colla

Markus Simonius

The reduction paradigm of quantum interferometry is reanalyzed. In contrast to widespread opinion it is shown to be amenable to straightforward mathematical treatment within ``every-users&#39;&#39; simple-minded single particle quantum mechanics (without reduction postulate or the like), exploiting only its probabilistic content.

E. Batista, J. F. Gomes, I. J. Lautenschleguer

The construction of a q-deformed N=2 superconformal algebra is proposed in terms of level 1 currents of ${\cal{U}}_{q} ({\widehat{su}}(2))$ quantum affine Lie algebra and a single real Fermi field. In particular, it suggests the expression for the q-deformed Energy-Momentum tensor in the Sugawara form. Its constituents generate two isomorphic quadratic algeb

A. Yu. Volkov

An algebraical background of the Lattice Conformal Field Theory is refined with the help of a novel $q$-exponential identity.

Razvan Gelca

The paper contains the construction of a topological quantum field theory with corners that underlies the smooth topological quantum field theory of Lickorish. Among other things, a contraction formula for diagrams is proved, the presence of the skein relation at the level of manifolds with boundary is shown and an explanation for the surgery formula for inv

C. B. Muratov, V. V. Osipov

An asymptotic method for finding instabilities of arbitrary $d$-dimensional large-amplitude patterns in a wide class of reaction-diffusion systems is presented. The complete stability analysis of 2- and 3-dimensional localized patterns is carried out. It is shown that in the considered class of systems the criteria for different types of instabilities are un

J. Cleymans, D. Elliott, H. Satz, R. L. Thews

The most abundantly produced hadron species in $Si\!-\!Au$ collisions at the BNL-AGS (nucleons, pions, kaons, antikaons and hyperons) are shown to be in accord with emission from a thermal resonance gas source of temperature $T\simeq 110$ MeV and baryochemical potential $μ_B \simeq 540$ MeV, corresponding to about 1/3 standard nuclear density. Our analysis t

T-Y Saito, I. R. Afnan

We re-examine the contribution of the $πN$ $S_{31}$ channel to the three-nucleon force for an energy dependent separable potential. Despite the lack of cancellation between the $S_{31}$ and the $P_{11}$ and $P_{33}$ channels, the total contribution of the three-nucleon force to the triton binding is still small.

B. S. Acharya

We present an ansatz which enables us to construct heterotic/M-theory dual pairs in four dimensions. It is checked that this ansatz reproduces previous results and that the massless spectra of the proposed dual pairs agree. The new dual pairs consist of M-theory compactifications on Joyce manifolds of $G_2$ holonomy and Calabi-Yau compactifications of hetero

Rashmi Ray, Joan Soto

In this article we show that if the electrons in a quantum Hall sample are subjected to a constant electric field in the plane of the material, comparable in magnitude to the background magnetic field on the system of electrons, a multiplicity of edge states localised in different regions of space is produced in the sample. The actions governing the dynamics

Fernando P. Devecchi, Marc Henneaux

The covariant path integral for chiral bosons obtained by McClain, Wu and Yu is generalized to chiral p-forms. In order to handle the reducibility of the gauge transformations associated with the chiral p-forms and with the new variables (in infinite number) that must be added to eliminate the second class constraints, the field-antifield formalism is used.

W. Siegel

Preserving the T-duality invariance of the continuum string in its random lattice regularization uniquely determines the random matrix model potential. For D=0 the duality transformation can be performed explicitly on the matrix action, and replaces color with flavor; invariance thus requires that the color and flavor groups be the same.

Adriano Di Giacomo

The dual superconductivity of QCD vacuum as a mechanism for colour confinement is reviewed. Recent evidence from lattice of monopole condensation is presented.

Changhyun Ahn, Soonkeon Nam

We study the quantum moduli space of vacua of $N=2$ supersymmetric $SU(N_c)$ gauge theories coupled to $N_f$ flavors of quarks in the fundamental representation. We identify the moduli space of the $N_c = 3$ and $N_f=2$ massless case with the full spectral curve obtained from the Lax representation of the Goryachev-Chaplygin top. For the case with {\it massi

Choonkyu Lee, Q-Han Park

We describe curved-space BPS dyon solutions, the ADM mass of which saturates the gravitational version of the Bogomol&#39;nyi bound. This generalizes self-gravitating BPS monopole solutions of Gibbons et al. when there is no dilaton.

Hung Cheng, S. P. Li

We propose using the method of subtraction to renormalize quantum gauge theories with chiral fermions and with spontaneous symmetry breaking. The Ward-Takahashi identities derived from the BRST invariance in these theories are complex and rich in content. We demonstrate how to use these identities to determine relationships among renormalization constants of

G. Domokos, S. Kovesi-Domokos

If different species of neutrinos possess transition magnetic moments, a conversion between species can occur in the Coulomb field of a nucleus. In the case of Dirac neutrinos this corresponds to an active to sterile conversion, whereas in the case of Majorana neutrinos, the conversion takes place between active species. The conversion cross sections grow wi

Axel Hoefer, L. M. Sehgal

We consider the process $e^+e^-\to N_1N_2$, where $N_1$ and $N_2$ are heavy Majorana particles, with relative $CP$ given by $η_{CP}=+1$ or $-1$, decaying subsequently via $N_1,N_2\to W^{\pm}e^{\mp}$. We derive the energy and angle correlation of the dilepton final state, both for like-sign ($e^{\mp}e^{\mp}$) and unlike-sign ($e^-e^+$) configurations. Interes

G. Dvali, G. F. Giudice, A. Pomarol

We point out that the $μ$-problem in theories in which supersymmetry breaking is communicated to the observable sector by gauge interactions is more severe than the one encountered in the conventional gravity-mediated scenarios. The difficulty is that once $μ$ is generated by a one-loop diagram, then usually $\bmu$ is also generated at the same loop order. T

F. Krüger, L. M. Sehgal

The effective Hamiltonian for the decay $b\to s l^+ l^-$ predicts a characteristic polarization for the final state lepton, which can serve as an important test of the underlying theory. The lepton polarization has, in addition to a longitudinal component $P_L$, two orthogonal components $P_T$ and $P_N$, lying in and perpendicular to the decay plane which ar

C. Boros, Liang Zuo-tang, Meng Ta-chung

It is shown that the hadronic dissociation of space-like $(Q^2>0)$ photons can be directly probed by performing measurements in the fragmentation region of transversely polarized and unpolarized proton beams at the electron-proton collider HERA. Measurements of momentum-distributions in the photon-fragmentation region in normal and in LRG (large rapidity gap

Z. Kunszt

I describe how to calculate cross sections for hard-scattering processes in high energy collisions at next to leading order in QCD. I consider infrared-safe quantities and I assume that the scattering amplitudes are known in analytic form up to next-to-leading order. The main topic is the description of the algorithm for the analytic cancellation of the soft

M. Velkovsky, E. Shuryak

In the instanton models the chiral phase transition is driven by a transition from random instanton-antiinstanton liquid and correlated instanton-antiinstanton molecules. So far this phenomenon was studied by numerical simulations, while we develop alternative semi-analytic approach. For two massless quark flavors, both instantons and ``molecules&#34; genera

Jae Sik Lee, Jae Kwan Kim

We study the effects on the Higgs boson mass from LEP precision data of the new physics explaining $R_b$-$R_c$ crisis. We implement a fit to LEP observables with the new physics. We obtain $M_H^{\rm New Physics} = 85 ^{+ 467}_{-56} ~~{\rm GeV}$. Comparing with the value of the SM fit, $M_H^{\rm SM} = 38^{+ 96}_{-21} ~~{\rm GeV}$, the errors are larger and th

J. P. Baptista, J. C. Fabris, S. V. B. Goncalves

We analyse the fate of density perturbation in the Brans-Dicke Theory, giving a general classification of the solutions of the perturbed equations when the scale factor of the background evolves as a power law. We study with details the cases of vacuum, inflation, radiation and incoherent matter. We find, for the a negative Brans-Dicke parameter, a significa

Hong-jun Xie, Takeshi Shirafuji

We introduce a generalized tetrad which plays the role of a potential for torsion and makes torsion dynamic. Starting from the Einstein-Cartan action with torsion, we get two field equations, the Einstein equation and the torsion field equation by using the metric tensor and the torsion potential as independent variables; in the former equation the torsion p

J. D. Bryngelson, D. Thirumalai

We argue that Kantor and Kardar&#39;s assertion that their simulation results contradict our criterion for the localization of a softly constrainted ideal polymer is incorrect. Our criterion is inapplicable to the model used in these simulations. We argue that our criterion for localization of as polymer with internal constraints strongly suggests that the m

H. Ding, M. R. Norman, J. C. Campuzano, M. Randeria

We report measurements of the momentum dependence of the superconducting gap in Bi_2Sr_2CaCu_2O_{8+x} (Bi2212) with angle-resolved photoemission spectroscopy using a dense sampling of the Brillouin zone in the vicinity of the Fermi surface. In the Y quadrant of the zone, where there are no complications from ghost bands caused by the superlattice, we find a

Karlo Penc, Hiroyuki Shiba, Frédéric Mila, Takuya Tsukagoshi

We propose a new mechanism which can lead to ferromagnetism in Hubbard models containing triangles with different on-site energies. It is based on an effective Hamiltonian that we derive in the strong coupling limit. Considering a one-dimensional realization of the model, we show that in the quarter-filled, insulating case the ground-state is actually ferrom

Michael Basler, Wolfram Krech, Konstantin Yu. Platov

We consider theoretically phase locking in a simple two-dimensional Josephson junction array consisting of two loops coupled via a joint line transverse to the bias current. Ring inductances are supposed to be small, and special emphasis is taken on the influence of external flux. Is is shown, that in the stable oscillation regime both cells oscillate with a

X. Leyronas, R. Combescot

We proceed to a systematic exploration of the low temperature dependence of the London penetration depth of isotropic superconductors within strong coupling theory in the clean limit. For a sizeable range of parameters, we find that strong coupling effects can reasonably simulate a power law dependence, sometimes with an excellent precision. In such cases it

T. A. Luce, W. Huebner, K. H. Bennemann

Using an electronic tight-binding theory we calculate the nonlinear magneto-optical response from an x-Cu/1Fe/Cu(001) film as a function of frequency and Cu overlayer thickness (x=3 ... 25). We find very strong spin-polarized quantum well oscillations in the nonlinear magneto-optical Kerr effect (NOLIMOKE). These are enhanced by the large density of Fe $d$ s

M. Haataja, J. A. Nieminen, T. Ala-Nissila

In this work we study the spreading dynamics of tiny liquid droplets on solid surfaces in the case where the ends of the molecules feel different interactions with respect to the surface. We consider a simple model of dimers and short chainlike molecules that cannot form chemical bonds with the surface. We use constant temperature Molecular Dynamics techniqu

E. Ben-Naim, P. L. Krapivsky

We study statistical properties of the Kolmogorov-Avrami-Johnson-Mehl nucleation-and-growth model in one dimension. We obtain exact results for the gap density as well as the island distribution. When all nucleation events occur simultaneously, the island distribution has discontinuous derivatives on the rays x_n(t)=nt, n=1,2,3... We introduce an accelerated

H. J. Mo, J. Miralda-Escude

A model of Lyman limit QSO absorption systems is investigated where they are produced in gaseous galactic halos with a two-phase structure: a hot phase at the halo virial temperature in approximate pressure equilibrium, and a cold, photoionized phase in the form of clouds confined by the pressure of the hot medium, and falling through it to the halo center.

David N. Spergel

Several lines of evidence suggest that some of the dark matter may be non-baryonic: the non-detection of various plausible baryonic candidates for dark matter inferred, e.g., from galaxy rotation curves and from cluster of galaxy velocity dispersions, the need for non-baryonic dark matter for theoretical models of galaxy formation, and the large discrepancy

M. Sean O&#39;Brien, J. Christopher Clemens, Steven D. Kawaler, Benjamin T. Dehner

We present an analysis of single-site time-series photometry of the pulsating pre-white dwarf PG 0122+200. We show the pulsations are consistent with a pattern of modes equally spaced in period; both the observed period range and spacing confirm that PG 0122 is a g-mode pulsator. PG 0122 shows a pattern similar to that seen in multi-site observations of PG 2

E. M. Puchnarewicz, K. O. Mason, E. Romero-Colmenero, F. J. Carrera

We present measurements of the optical and X-ray continua of 108 AGN (Seyfert 1s and quasars) from the Rosat International X-ray/Optical Survey (RIXOS). The sample covers a wide range in redshift (0<z<3.3), in X-ray spectral slope (-1.5 <ax<2.6) and in optical-to-X-ray ratio (0.4$<aox<1.5). A correlation is found between ax and aox; similar correlations have

S. Cassisi, M. Castellani, V. Castellani

We investigate the evolution of metal deficient stellar structures, presenting H-burning isochrones covering cluster ages from 800 Myr to 7 Gyr. Evolutionary evidences for selection effects in the metallicity distribution of very metal poor H-burning red giants are reported. The evolution of stars during central and shell He burning is further investigated,

C. Garcia-Gomez, E. Athanassoula, A. Garijo

In this paper we test the performance of explicit simulations of groups of galaxies, (i.e. simulations in which each galaxy is treated as a mass point and the physics of the interactions is modelled by specific analand the physics of the interactions is modelled by specific analytical prescriptions for merging conditions), by comparing them with fully self-c

Don N. Page

The regularized expectation value of the stress-energy tensor for a massless bosonic or fermionic field in 1+1 dimensions is calculated explicitly for the instantaneous vacuum relative to any Cauchy surface (here a spacelike curve) in terms of the length L of the curve (if closed), the local extrinsic curvature K of the curve, its derivative K&#39; with resp

France Allard, Peter H. Hauschildt, Isabelle Baraffe, Gilles Chabrier

We present preliminary non-grey model atmospheres and interiors for cool brown dwarfs. The resulting synthetic spectra are compared to available spectroscopic and photometric observations of the coolest brown dwarf yet discovered, Gl229B (Nakajima \etal, 1995). Despite recognized shortcomings of current methane opacities, we find that the model spectra provi

Yu. G. Zarhin

The aim of this paper is to propose an ``elementary&#34; approach to Coleman&#39;s theory of p-adic abelian integrals. Our main tool is a theory of commutative p-adic Lie groups (the logarithm map); we use neither dagger analysis nor Monsky-Washnitzer cohomology theory. Notice that we also treat the case of bad reduction. A preliminary version of this paper