May 1997 arXiv papers — page 3

Sergei Alexandrov, Ignati Grigentch, Dmitri Vassilevich

We consider a space-time with spatial sections isomorphic to the group manifold of SU(2). Triad and connection fluctuations are assumed to be SU(2)-invariant. Thus, they form a finite dimensional phase space. We perform non-perturbative path integral quantization of the model. Contarary to previous claims the path integral measure appeared to be non-singular

Robert Bartnik

The residual gauge freedom within the null quasi-spherical coordinate condition is studied, for spacetimes admitting an expanding, shear-free null foliation. The freedom consists of a boost and rotation at each coordinate sphere, corresponding to a specification of inertial frame at each sphere. Explicit formulae involving arbitrary functions of two variable

Valter Moretti, Devis Iellici

A method to regularize and renormalize the fluctuations of a quantum field in a curved background in the $ζ$-function approach is presented. The method produces finite quantities directly and finite scale-parametrized counterterms at most. These finite couterterms are related to the presence of a particular pole of the effective-action $ζ$ function as well a

M. J. Cassidy

The 1--loop effective Lagrangian for a massive scalar field on an arbitrary causality violating spacetime is calculated using the methods of Euclidean quantum field theory in curved spacetime. Fields of spin 1/2, spin 1 and twisted field configurations are also considered. In general, we find that the Lagrangian diverges to minus infinity at each of the nth

Michael Murat, Gary S. Grest, Kurt Kremer

Diffusion of symmetric diblock copolymer chains in macroscopically oriented lamellar block copolymers are studied in a molecular dynamics simulation. Results for diffusion constant both parallel $D_\parallel$ and perpendicular $D_\perp$ to the lamellar planes are compared to results in the disordered one phase region. For diblocks of length N=40 (1.1 N_e) an

P. Simon

We discuss the critical behaviour of 2D Ising and q-states Potts models coupled by their energy density. We found new tricritical points. The procedure employed is the renormalisation approach of the perturbations series around conformal field theories representing pure models as already used for disordered spins models. This analysis could be useful to unde

Michael R. Swift, Alan J. Bray, Amos Maritan, Marek Cieplak

The exact determination of ground states of small systems is used in a scaling study of the random-field Ising model. While three variants of the model are found to be in the same universality class in 3 dimensions, the Gaussian and bimodal models behave distinctly in 4 dimensions with the latter apparently having a discontinuous jump in the magnetization. A

T. Mertelj, J. Demsar, B. Podobnik, I. Poberaj

The temperature dependence of the energy relaxation of photoexcited (PE) carriers is used as a probe of the electronic structure of YBa_2Cu_3O_(7-d) in the insulating d~0.8 and metallic d~0.1 phases. The energy relaxation rate to phonons is obtained by measuring the non-equilibrium phonon occupation number, n_neq, with pulsed Raman Stokes/anti-Stokes spectro

N. Hayashi, M. Ichioka, K. Machida

An isolated single vortex is considered within the framework of the quasiclassical theory. The local density of states around a vortex is calculated in a clean type II superconductor with an anisotropy. The anisotropy of a superconducting energy gap is crucial for bound states around a vortex. A characteristic structure of the local density of states, observ

O. Gunnarsson

The photoemission spectrum and the specific heat are studied in the Hubbard model of small clusters including orbital degeneracy. We focus on the degeneracy and valence dependence in the limit of a large Coulomb interaction. For integer valence, it is found that the degeneracy increases the width of the photoemission spectrum and it reduces the contribution

K. A. Kouznetsov, A. G. Sun, B. Chen, A. S. Katz

We report a new class of $c$-axis Josephson tunneling experiments in which a conventional superconductor (Pb) is deposited across a single twin boundary of a YBa_2Cu_3O_{7-δ} crystal. We measure the critical current as a function of magnitude and angle of magnetic field applied in the plane of the junction. In all samples, we observe a clear experimental sig

Martin Greiter

In a comment on my recent manuscript on the pi-particle [cond-mat/9705049], Demler et al. [cond-mat/9705191] argued that there is a correction to the chemical potential which enters the expression for the energy of the pi-particle given in [Demler and Zhang, Phys. Rev. Lett. 77, 4126 (1995)]. This is shown to be incorrect. I further offer an interpretation f

Nikolai F. Rulkov, Lev S. Tsimring

Methods of communications using chaotic signals use an ability of a chaos generator (encoder) and matched response system (decoder) to behave identically despite the instability of chaotic oscillations. Chaotic oscillations cover a wide spectral domain and can efficiently mask an information signal scrambled by the chaotic encoder. At the same time the wide

S. C. Beck, D. M. Kelly, J. H. Lacy

We have obtained near-infrared images and mid-infrared spectra of the starburst core of the dwarf Wolf-Rayet galaxy He 2-10. We find that the infrared continuum and emission lines are concentrated in a flattened ellipse 3-4'' or 150 pc across which may show where a recent accretion event has triggered intense star formation. The ionizing radiation fr

Eve C. Ostriker

We construct a two-parameter family of models for self-collimated, radially self-similar magnetized outflows from accretion disks. A flow at zero initial poloidal speed leaves the surface of a rotating disk and is accelerated and redirected toward the pole by helical magnetic fields threading the disk. At large distances from the disk, the flow streamlines a

Wenbin Li, Neal J. Evans, Elizabeth A. Lada

We have carried out a simultaneous, multi-band (J, H, K) survey over an area of 1320 arcmin^2 in the L1630 region, concentrating on the region away from the dense molecular cores and with modest visual extinctions (\leq 10 mag). Previous studies found that star formation in L1630 occurs mainly in four localized clusters, which in turn are associated with the

Marc Davis, Amber Miller, Simon D. M. White

The relative pair dispersion of galaxies has for the past decade been the standard measure of the thermal energy of fluctuations in the observed galaxy distribution. This statistic is known to be unstable, since it is a pair-weighted measure that is very sensitive to rare, rich clusters of galaxies. As a more stable alternative, we here present a single-part

Andrew A. de Laix

We consider the gravitational lensing produced by long cosmic strings formed in a GUT scale phase transition. We derive a formula for the deflection of photons which pass near the strings that reduces to an integral over the light cone projection of the string configuration plus constant terms which are not important for lensing. Our strings are produced by

Max Pettini, David V. Bowen

We have determined the metallicity of the $z_{abs} = 1.0093$ damped Lyman alpha system in the bright QSO EX 0302-223; this is only the third such measurement at redshifts $z \simlt 1$. Unlike the previous two cases, we find that the abundance of Zn is only a factor of $\sim 2$ lower than in the Galactic interstellar medium today and is entirely compatible wi

D. Huybrechts

The paper generalizes some of the well-known results for K3 surfaces to higher-dimensional irreducible symplectic (or, equivalently, compact irreducible hyperkaehler) manifolds. In particular, we discuss the projectivity of such manifolds and their ample resp. Kaehler cones. It is proved that the period map surjects any non-empty connected component of the m

Aaron Bertram, Ionut Ciocan-Fontanine, William Fulton

We give formulas for the products of classes of Schubert varieties in the quantum cohomology rings of Grassmannians, in terms of the combinatorics of partitions and tableaux.

David A. Buote

(Abridged) We examine the theoretical relationship between Omega_0 and substructure in galaxy clusters which are formed by the collapse of high density peaks in a gaussian random field. The radial mass distributions of the clusters are computed from the spherical accretion model using the adiabatic approximation following Ryden & Gunn. For a cluster of mass,

Marc Kamionkowski, Arthur Kosowsky

Inflation predicts specific relations between the amplitudes and spectral indices of the primordial spectrum of density (scalar metric) perturbations and gravitational waves (tensor metric perturbations). Detection of a stochastic gravitational-wave background is essential for identifying this unmistakable signature. Polarization of the cosmic microwave back

James C. Lombardi, Frederic A. Rasio, Stuart L. Shapiro

Using an energy variational method, we calculate quasi-equilibrium configurations of binary neutron stars modeled as compressible triaxial ellipsoids obeying a polytropic equation of state. Our energy functional includes terms both for the internal hydrodynamics of the stars and for the external orbital motion. We add the leading post-Newtonian (PN) correcti

Diptiman Sen, R. K. Bhaduri

For a one-dimensional model in which the two-body interactions are long-range and strong, the system almost crystallizes. The harmonic modes of such a lattice can be used to compute the ground state wave function and the dynamical density-density correlations. We use this method to calculate the density corrrelations in the Calogero-Sutherland model. We show

Christian von Ferber, Yurij Holovatch

We explore and calculate the rich scaling behavior of copolymer networks in solution by renormalization group methods. We establish a field theoretic description in terms of composite operators. Our 3rd order resummation of the spectrum of scaling dimensions brings about remarkable features: The special convexity properties of the spectra allow for a multifr

E. Sharpe

In this paper we study extremal transitions between heterotic string compactifications, i.e., transitions between pairs (M,V) where M is a Calabi-Yau manifold and V a gauge bundle. Bundle transitions are described using language recently espoused by Friedman, Morgan, Witten. In addition, partly as a check on our methods, we also study how small instantons ar

Yuji Satoh

We investigate quantum aspects of the three dimensional (BTZ) black holes. The discussions are devoted to two subjects: the thermodynamics of quantum scalar fields and the string theory in the three dimensional black hole backgrounds. We take two approaches to the thermodynamics. In one approach we use mode expansion, and in the other we use Hartle-Hawking G

Yuji Satoh

Spectra of a string in $ SL(2,R) $ and three dimensional (BTZ) black hole geometry are discussed. We consider a free field realization of ^sl (2,R) different from the standard ones in treatment of zero-modes. Applying this to the string model in SL(2,R), we show that the spectrum is ghost-free. The essence of the argument is the same as Bars' resolution

Naomichi Hatano, David R. Nelson

A delocalization phenomenon is studied in a class of non-Hermitian random quantum-mechanical problems. Delocalization arises in response to a sufficiently large constant imaginary vector potential. The transition is related to depinning of flux lines from extended defects in type-II superconductors subject to a tilted external magnetic field. The physical me

Itzhak Bars, Costas Kounnas

An action for a string and a particle with two timelike dimensions is proposed and analyzed. Due to new gauge symmetries and associated constraints, the motion of each system in the background of the other is equivalent to effective motion with a single timelike dimension. The quantum constraints are consistent only in critical dimensions. For the bosonic sy

Ludwik Dabrowski, Fabrizio Nesti, Pasquale Siniscalco

The 27-dimensional Hopf algebra A(F), defined by the exact sequence of quantum groups A(SL(2,C))->A(SL_q(2))->A(F), q^3=1, is studied as a finite quantum group symmetry of the matrix algebra M(3,C), describing the color sector of Alain Connes' formulation of the Standard Model. The duality with the Hopf algebra H,investigated in a recent work by Robert C

A. Deandrea

Recent high-precision measurements of atomic parity-nonconserving transitions between the 6S and 7S states of cesium allow for a determination of the weak nuclear charge with a precision of 1.3%, providing an improved test of the standard model at low energy. Implications for new physics are examined in terms of low energy effects on the weak charge, in part

L. Frappat, V. Hussin, G. Rideau

We present a classification of the possible quantum deformations of the supergroup $GL(1|1)$ and its Lie superalgebra $gl(1|1)$. In each case, the (super)commutation relations and the Hopf structures are explicitly computed. For each $R$ matrix, one finds two inequivalent coproducts whether one chooses an unbraided or a braided framework while the correspond

T. A. Larsson

We describe a class of non-central extensions of the diffeomorphism algebra in N-dimensional spacetime, and construct lowest-energy modules thereof, thus generalizing work of Eswara-Rao and Moody. There is one representation for each representation of $Vir\ltimes_{k_0}\km{gl(N)}$ (an extension of the semi-direct product). Similar modules are constructed for

R. Brout, R. Parentani

The notion of time in cosmology is revealed through an examination of transition matrix elements of radiative processes occurring in the cosmos. To begin with, the very concept of time is delineated in classical physics in terms of correlations between the succession of configurations which describe a process and a standard trajectory called the clock. The t

Antonio Dobado, Antonio L. Maroto

In the presence of a curved space-time with torsion, the divergence of the leptonic current gets new contributions from the curvature and the torsion in addition to those coming from the electroweak fields. However it is possible to define a new lepton current which is gauge and local Lorentz invariant whose divergence gets no contribution from the torsion.

Shaojin Qin, Michele Fabrizio, Lu Yu, Masaki Oshikawa

Conformal field theory gives quite detailed predictions for the low energy spectrum and scaling exponents of a massless Luttinger liquid at generic filling in the presence of an impurity. While these predictions were verified for half-filled systems, there was till now no analysis away from this particular filling. Here, we fill in this gap by numerically in

N. Gisin, S. Massar

We present Quantum Cloning Machines (QCM) that transform N identical qubits into $M>N$ identical copies and we prove that the fidelity (quality) of these copies is optimal. The connection between cloning and measurement is discussed in detail. When the number of clones M tends towards infinity, the fidelity of each clone tends towards the optimal fidelity th

W. X. Ma, R. K. Bullough, P. J. Caudrey

By starting from known graded Lie algebras, including Virasoro algebras, new kinds of time-dependent evolution equations are found possessing graded symmetry algebras. The modified KP equations are taken as an illustrative example: new modified KP equations with $m$ arbitrary time-dependent coefficients are obtained possessing symmetries involving $m$ arbitr

W. X. Ma, R. K. Bullough, P. J. Caudrey, W. I. Fushchych

Polynomial-in-time dependent symmetries are analysed for polynomial-in-time dependent evolution equations. Graded Lie algebras, especially Virasoro algebras, are used to construct nonlinear variable-coefficient evolution equations, both in 1+1 dimensions and in 2+1 dimensions, which possess higher-degree polynomial-in-time dependent symmetries. The theory al

Y. Orlov

It is shown that quantum-type coherence, leading to indeterminism and interference of probabilities, may in principle exist in the absence of the Planck constant and a Hamiltonian. Such coherence is a combined effect of a symmetry (not necessary physical) and semantics. The crucial condition is that symmetries should apply to logical statements about observa

Y. Orlov

It is proved in the frame of standard quantum mechanics that selection of different ensembles emerging from measurements of an observable leads to identification of corresponding reductions of the initial, premeasured state. This solves the problem of ``nonlocality`` observed in EPR-Bohm-type experiments.

Yu Shi

Study on pre- and postselected quantum system indicates that ``product rule'' and ``sum rule'' for elements of reality should be abandoned. We show that this so-called non-partial realism can refute arguments against hidden variables in a unified way, and might save local realism.

Paolo Aschieri, Leonardo Castellani

We review the construction of the multiparametric quantum group $ISO_{q,r}(N)$ as a projection from $SO_{q,r}(N+2) $ and show that it is a bicovariant bimodule over $SO_{q,r}(N)$. The universal enveloping algebra $U_{q,r}(iso(N))$, characterized as the Hopf algebra of regular functionals on $ISO_{q,r}(N)$, is found as a Hopf subalgebra of $U_{q,r}(so(N+2))$

C. Quesne

Some new algebraic structures related to the coloured Yang-Baxter equation, and termed coloured Hopf algebras, are reviewed. Coloured quantum universal enveloping algebras of Lie algebras are defined in this context. An extension to the coloured graded Yang-Baxter equation and coloured Hopf superalgebras is also presented. The coloured two-parameter quantum

R. M. Kashaev

The Teichmüller space of punctured surfaces with the Weil-Petersson symplectic structure and the action of the mapping class group is realized as the Hamiltonian reduction of a finite dimensional symplectic space where the mapping class group acts by symplectic rational transformations. Upon quantization the corresponding (projective) representation of the m

A. L. Carey, A. Paolucci, R. B. Zhang

The Cuntz algebra carries in a natural way the structure of a module algebra over the quantized universal enveloping algebra $U_q(g)$, and the structure of a co-module algebra over the quantum group $G_q$ associated with $U_q(g)$. These two algebraic structures are dual to each other via the duality between $G_q$ and $U_q(g)$.

C. Quesne

Quite recently, a ``coloured'' extension of the Yang-Baxter equation has appeared in the literature and various solutions of it have been proposed. In the present contribution, we introduce a generalization of Hopf algebras, to be referred to as coloured Hopf algebras, wherein the comultiplication, counit, and antipode maps are labelled by some colou

Mikhail Kozlov

We calculate an effective electric field on the unpaired electron in the YbF molecule. This field determines sensitivity of the molecular experiment to the electric dipole moment of the electron. We use experimental value of the spin-doubling constant to estimate the admixture of the configuration with the hole in the 4f-shell of Ytterbium to the ground stat

V. P. Frolov, D. V. Fursaev

We demonstrate how Sakharov's idea of induced gravity allows one to explain the statistical-mechanical origin of the entropy of a black hole. According to this idea, gravity becomes dynamical as the result of quantum effects in the system of heavy constituents of the underlying theory. The black hole entropy is related to the properties of the vacuum in

Ricardo Amorim, Ronaldo Thibes

The procedure for Abelian conversion of second class constraints due to Batalin, Fradkin, Fradkina and Tyutin is considered at quantum level, by using the field-antifield formalism. It is argued that quantum effects can obstruct the process. In this case, Wess-Zumino fields may be introduced in order to restore the lost symmetries.

J. Ambjorn, C. Kristjansen, Y. Watabiki

We construct a reparametrization invariant two-point function for c=-2 conformal matter coupled to two-dimensional quantum gravity. From the two-point function we extract the critical indices νand η. The results support the quantum gravity version of Fisher's scaling relation. Our approach is based on the transfer matrix formalism and exploits the formul

Ulf Lindstrom, Maxim Zabzine

We discuss the topological properties of the manifold of coupling constants for multi-coupling deformations of conformal field theories. We calculate the Euler and Betti numbers and briefly discuss physical applications of these results.

I. N. McArthur, T. D. Gargett

For nonsupersymmetric theories, the one-loop effective action can be computed via zeta function regularization in terms of the functional trace of the heat kernel associated with the operator which appears in the quadratic part of the action. A method is developed for computing this functional trace by exploiting its similarity to a Gaussian integral. The pr

John Ellis, Toby Falk, Keith A. Olive, Michael Schmitt

A significant lower limit on the mass of the lightest neutralino χcan be obtained by combining the results from sparticle searches at LEP at centre-of-mass energies up to 172 GeV with cosmological considerations, if it is assumed that the χis stable. Exclusion domains from slepton searches close m_χ\sim 0 loopholes that were left open by previous lower-energ

S. J. Pollock

We examine the $Q^2$ evolution of gluon polarization in polarized nucleons. As is well known, the evolution of $α_s ΔG(Q^2)$ is negligible for typical momentum transfer variations found in experimental deep inelastic scattering. As $α_s$ increases, however, the leading nonzero term in the evolution equation for the singlet first moment reduces the magnitude

S. Mrenna

We calculate the event rates for the Standard Model production of two photons plus missing mass through the process electron positron to gamma gamma nu nubar, where nu is any of the three neutrino flavors, at LEP energies. This process can be a background to new physics signatures, such as that expected from supersymmetry with a higgsino or gravitino LSP. Th

Michael Gronau

CP violation in K and B decays is reviewed in the Standard Model (SM) and beyond the SM. In K decays, one is seeking first evidence for CP violation in direct $K\to ππ$ decays. This would not give a precise quantitative test for the present explanation of CP violation in terms of a phase in the Cabibbo-Kobayashi-Maskawa (CKM) matrix. Such tests are provided

A. F. Martini, M. J. Menon

We analyse pp elastic scattering data at the highest accelerator energy region (between 10 and 63 GeV) through a multiple diffraction approach. The use of Martin's formula in a model developed earlier is substituted by the introduction of a complex elementary (parton-parton) amplitude. With this the total cross section and the real part of the hadronic a

V. Bernard, A. H. Blin, B. Hiller, Yu. P. Ivanov

The problem of the $ρ$ meson resonance solution in the extended NJL model is studied. It has been shown previously that the solution for the $ρ$ meson changes smoothly from a bound state to a "virtual state" when the vector channel attraction becomes too weak to support bound state solutions. We have found that together with these solutions a separat

Shin Ishida, Muneyuki Ishida, Taku Ishida, Kunio Takamatsu

Recently we have shown an evidence for existence of σ-particle in the previous works; where the ππS-wave phase shift is reanalyzed, by introducing a repulsive background suggested by the chiral symmetry, and by applying a new method of Interfering Breit-Wigner Amplitudes. In this work we also show, reanalyzing the KπS-wave phase shift from a similar standpoi

S. M. Bilenky, C. Giunti, W. Grimus

What information about the neutrino mass spectrum and mixing matrix can be inferred from the existing neutrino oscillation data? We discuss here the answer to this question in the case of mixing of three and four neutrinos. We present the constraints on the effective Majorana mass <m> that can be obtained from the results of reactor neutrino oscillation expe

L. Herrera, N. O. Santos

The geodesic equations are integrated for the Lewis metric and the effects of the different parameters appearing in the Weyl class on the motion of test particles are brought out. Particular attention deserves the appearance of a force parallel to the axial axis and without Newtonian analogue.

Yasushi Mino, Misao Sasaki, Takahiro Tanaka

We discuss the leading order correction to the equation of motion of a particle with spin on an arbitrary spacetime. A particle traveling in a curved spacetime is known to trace a geodesic of the background spacetime if the mass of the particle is negligibly small. For a spinning particle, it is known that there appears a term due to the coupling of the spin

Carlos O. Lousto, Richard H. Price

Numerical relativity, applied to collisions of black holes, starts with initial data for black holes already in each other&#39;s strong field. The initial hypersurface data typically used for computation is based on mathematical simplifying prescriptions, such as conformal flatness of the 3-geometry and longitudinality of the extrinsic curvature. In the case

T. A. Vilgis, M. Otto

In this note we present a scaling theory for the elasticity of olympic gels, i.e., gels where the elasticity is a consequence of topology only. It is shown that two deformation regimes exist. The first is the non affine deformation regime where the free energy scales linear with the deformation. In the large (affine) deformation regime the free energy is sho

W. D. Heiss, R. G. Nazmitdinov

It is argued that various kind of shell structure which occurs at specific values of the magnetic field should be observable in small quantum dots in the addition energies and the magnetic susceptibility.

C. Pich, F. Schwabl

We study planar ferromagnetic spin-chain systems with weak antiferromagnetic inter-chain interaction and dipole-dipole interaction. The ground state depends sensitively on the relative strengths of antiferromagnetic exchange and dipole energies kappa=J&#39;a^2c/(g_Lμ_B)^2. For increasing values of κ, the ground state changes from a ferromagnetic via a collin

David Tsiklauri

Based on the experimental data from Weninger, Putterman & Barber, Phys. Rev. (E), 54, R2205 (1996), we offer an alternative interpretation of their experimetal results. A model of sonoluminescing bubble which proposes that the electromagnetic radiation originates from two sources: the isotropic black body or bramsstrahlung emitting core and dipole radiation-

Stephane Cueille, Clement Sire

We introduce an extended Smoluchowski equation describing coagulation processes for which clusters of mass s grow between collisions with $ds/dt=As^β$. A physical example, dropwise condensation is provided, and its collision kernel K is derived. In the general case, the gelation criterion is determined. Exact solutions are found and scaling solutions are inv

Christian von Ferber, Yurij Holovatch

We study scaling properties of self avoiding polymer stars and networks of arbitrary given but fixed topology. We use massive field theoretical renormalization group framework to calculate critical exponents governing their universal properties (star exponents). Calculations are performed directly in three dimensions, renormalization group functions are obta

Christian von Ferber, Yurij Holovatch

While multifractal spectra are convex, general field theoretic arguments show that power of field operators $ϕ^f$ yield a concave spectrum of exponents as function of $f$. This is resolved by appropriate choice of operators to describe multifractal moments. In a Lagrangian field theory of two mutually interacting species of fields $ϕ,ψ$, operators $O_{f&#39;

Christian von Ferber, Yurij Holovatch

We explore the rich scaling behavior of copolymer networks in solution. We establish a field theoretic description in terms of composite operators. Our 3rd order resummation of the spectrum of scaling dimensions brings about remarkable features: Convexity of the spectra allows for a multifractal interpretation. This has not been conceived for power of field

Joel Feldman, Manfred Salmhofer, Eugene Trubowitz

Regularity of the deformation of the Fermi surface under short-range interactions is established to all orders in perturbation theory. The proofs are based on a new classification of all graphs that are not doubly overlapping. They turn out to be generalized RPA graphs. This provides a simple extension to all orders of the regularity theorem of the Fermi sur

N. K. Wilkin, Henrik Jeldtoft Jensen

We investigate the effects of disorder on a layered superconductor. The clean system is known to have a first order phase transition which is clearly identified by a sharp peak in the specific heat. The peak is lost abruptly as the strength of the disorder is increased. Hence, for strong disorder there is no phase transition as a function of temperature but

Heinz Horner, Reimer Kuehn

We review the theory of neural networks, as it has emerged in the last ten years or so within the physics community, emphasizing questions of biological relevance over those of importance in mathematical statistics and machine learning theory.

Hirokazu Tsunetsugu, Masatoshi Imada

Conductivity and Hall coefficient for various types of t-J ladders are calculated as a function of temperature and frequency by numerical diagonalization. A crossover from an incoherent to a coherent charge dynamics is found at a temperature T_{coh}. There exists another crossover at T_{PG} below which a pseudogap opens in the optical spectra, induced by the

Max Chaves

Recent high resolution experiments show a strong peak at Q = 1.9 Ang^{-1} in liquid helium&#39;s dynamic structure factor that exhibits a singular dependence on temperature. The theoretical situation is briefly reviewed, and the comment is made that the simplest possible explanation is that at the lambda point a macroscopic number of molecules actually begin

Subir Sachdev

The physics of non-zero temperature dynamics and transport near quantum-critical points is discussed by a detailed study of the O(N)-symmetric, relativistic, quantum field theory of a N-component scalar field in $d$ spatial dimensions. A great deal of insight is gained from a simple, exact solution of the long-time dynamics for the N=1 d=1 case: this model d

David Carter, Ralph Becket, Manny Rayner, ; Robert Eklund

In this paper we describe how the translation methodology adopted for the Spoken Language Translator (SLT) addresses the characteristics of the speech translation task in a context where it is essential to achieve easy customization to new languages and new domains. We then discuss the issues that arise in any attempt to evaluate a speech translator, and pre

David S. Davis, William C. Keel, John S. Mulchaey, Patricia A. Henning

We report the results of the spatial analysis of deep ROSAT HRI observations, optical imaging and spectroscopy, and high-resolution VLA H I and continuum imaging of NGC 1961 and NGC 2276. These spirals were selected as showing some previous evidence for interaction with a surrounding (hot) diffuse medium. Our results favor most aspects of these galaxies as b

Kristian Pedersen, Yuzuru Yoshii, Jesper Sommer-Larsen

New X-ray observations of the sparse NGC 3258 group of galaxies made by the ASCA satellite with good spectral and spatial resolution has revealed that this group has a gravitational potential deep enough to prohibit significant mass removal from the system. The baryonic fraction within 240 kpc is found to be 0.065 +0.051/-0.020 for h_{50}=1, where h_{50}=H_0

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

We present N-body simulations of groups of galaxies with a number of very different initial conditions. These include spherical isotropic, nonspherical anisotropic collapses and virialised spherical systems. In all cases but one the merging instability leads to the formation of a giant central galaxy in the center of the group. The initial conditions of the

A. F. Heavens, A. N. Taylor

In this paper we consider methods of analysis and optimal design of redshift surveys. In the first part, we develop a formalism for analysing galaxy redshift surveys which are essentially two-dimensional, such as thin declination slices. The formalism is a power spectrum method, using spherical coordinates, allowing the distorting effects of galaxy peculiar

Yogesh Wadadekar, Braxton Robbason, Ajit Kembhavi

We propose a two dimensional galaxy fitting algorithm to extract parameters of the bulge, disk, and a central point source from broad band images of galaxies. We use a set of realistic galaxy parameters to construct a large number of model galaxy images which we then use as input to our galaxy fitting program to test it. We find that our approach recovers al

Eliani Ardi, Shogo Inagaki

We have studied the distribution of forces in gravitational systems through numerical experiments. Data were taken from an N-body simulation in an expanding universe. Before clustering, the distribution of random forces was represented as a Holtsmark distribution; the nearest-neighbor distribution is also shown as a comparison. The analytical and simulation

Leslie W. Looney, Lee G. Mundy, W. J. Welch

We present sub-arcsecond resolution imaging of the $λ$ = 2.7 mm continuum emission from the young, embedded system L1551 IRS5 using the nine-element, high-resolution configuration of the BIMA array. The observed emission arises from two compact sources separated by $0\farcs$35, coinciding with the two sources seen at $λ$ = 2 cm and $λ$ = 1.3 cm. When the hig

Kei Iida, Katsuhiko Sato

Rates for nucleation of two-flavor quark matter in a neutron star core, originally composed of nuclear matter in $β$ equilibrium, are calculated at zero temperature by a quantum tunneling analysis incorporating the electrostatic energy. We find that a nucleated droplet would develop into bulk matter due to electron screening effects.

O. Bienaymé, C. Pichon

In a recent Letter, Cowsik, Ratnam and Bhattacharjee (1996a) have built a dynamically self-consistent spatial distribution of particles of galactic dark matter. They have come up with the rather unorthodox conclusion that the mean velocity dispersion of dark matter particles ``should be $600 kms$ or larger&#39;&#39;. Their letter triggered immediate comments

Karl Landsteiner, Esperanza Lopez, David A. Lowe

Starting with configurations of fourbranes, fivebranes, sixbranes and orientifolds in Type IIA string theory we derive via M-theory the curves solving N=2 supersymmetric gauge theories with gauge groups SO(N) and Sp(2N). We also obtain new curves describing theories with product gauge groups. A crucial role in the discussion is played by the interaction of t

T. Csorgo

A generalization of the core/halo model to the Bose-Einstein correlation function of any number of particles is presented. In particular, a simple prediction is obtained for the intercept parameter of the n-particle inclusive Bose-Einstein correlation functions for arbitrary large values of n.

T. Csorgo, J. Zimanyi

Brooding over bosons, wave packets and Bose - Einstein correlations, we find that a generalization of the pion-laser model for the case of overlapping wave-packets is analytically solvable with complete n-particle symmetrization. The effective radius parameter of the two-particle correlation function is reduced for low values and enlargened for high values o

J. Zimanyi, T. Csorgo

Brooding over bosons, wave packets and Bose - Einstein correlations, we present a generic quantum mechanical system that contains arbitrary number of bosons characterized by wave-packets and that can undergo a Bose-Einstein condensation either by cooling, or increasing the number density of bosons, or by increasing the overlap of the multi-boson wave-packet

Mirjam Cvetic, Finn Larsen

We derive the wave equation for a minimally coupled scalar field in the background of a general rotating five-dimensional black hole. It is written in a form that involves two types of thermodynamic variables, defined at the inner and outer event horizon, respectively. We model the microscopic structure as an effective string theory, with the thermodynamic p

L. V. E. Koopmans

Temporary withdrawn.

S. Jadach, W. Placzek, B. F. L. Ward

We present the theoretical basis and sample Monte Carlo data for the YFS exponentiated calculation of $e^+e^- \to Z Z \to f_1\bar f_1 + \bar f_2 f_2$ at and beyond LEP2 energies, where the left-handed part of $f_i$ is a component of an $SU_{2L}$ doublet, $i=1,2$. The calculation is performed for both SM couplings and for anomalous $ZZV$ triple gauge boson co

H. C. Rosu

I present the factorization(s) of the Wheeler-DeWitt equation for vacuum FRW minisuperspace universes of arbitrary Hartle-Hawking factor ordering, including the so-called strictly isospectral supersymmetric method. By the latter means, one can introduce an infinite class of singular FRW minisuperspace wavefunctions characterized by a Darboux parameter that m

S. Jadach, W. Placzek, M. Skrzypek, B. F. L. Ward

We realize, by Monte Carlo event generator methods, the exact O}(α)$ YFS exponentiated calculation of $e^+e^- \to W^+ W^- (\to f_1\bar f&#39;_1 + \bar f_2 f&#39;_2)$ at and beyond LEP2 energies, where the left-handed parts of $f_i$ and $f&#39;_i$ are the respective upper and lower components of an $SU_{2L}$ doublet, $i=1,2$. Our calculation is gauge invarian

G. Curio

We compare the spectrum of chiral multiplets in the N=1 vacua of the heterotic string on a Calabi-Yau together with an $E_8\times E_8$ vector bundle and F-theory on a smooth Calabi-Yau fourfold. Under suitable restrictions we show agreement using an index-computation.