April 1996 arXiv papers — page 5

John Lott

This is an expository article on the question of whether zero lies in the spectrum of the Laplace-Beltrami operator acting on differential forms on a manifold.

N. V. Brilliantov, Yu. A. Andrienko, P. L. Krapivsky, J. Kurths

We reveal the fractal nature of patterns arising in random sequential adsorption of particles with continuum power-law size distribution, $P(R)\sim R^{α-1}$, $R \le R_{\rm max}$. We find that the patterns become more and more ordered as $α$ increases, and that the Apollonian packing is obtained at $α\to \infty $ limit. We introduce the entropy production rat

Enrique Macia, Francisco Dominguez-Adame

We numerically investigate the effects of inhomogeneities in the energy spectrum of aperiodic semiconductor superlattices, focusing our attention on Thue-Morse and Fibonacci sequences. In the absence of disorder, the corresponding electronic spectra are self-similar. The presence of certain degree of randomness, due to imperfections occurring during the grow

E. E. Narimanov, A. D. Stone

An analytic theory is developed for the density of states oscillations in quantum wells in a magnetic field which is tilted with respect to the barrier planes. The main oscillations are found to come from the simplest one or two-bounce periodic orbits. We calculate their period and stability analytically and find an infinite sequence of destabilizations foll

S. Brehmer, H. -J. Mikeska, U. Neugebauer

We investigate the phase diagram of antiferromagnetic spin ladders with additional exchange interactions on diagonal bonds by variational and numerical methods. These generalized spin ladders interpolate smoothly between the $S=1/2$ chain with competing nn and nnn interactions, the $S=1/2$ chain with alternating exchange and the antiferromagnetic $S=1$ chain

Stefano Galluccio, Yi-Cheng Zhang

Using a generalized transfer matrix method we exactly solve the Schrödinger equation in a time periodic potential, with discretized Euclidean space-time. The ground state wave function propagates in space and time with an oscillating soliton-like wave packet and the wave front is wedge shaped. In a statistical mechanics framework our solution represents the

Kikuo Harigaya

Charge-transfer (CT) exciton effects are investigated for the optical absorption spectra of crosslinked C60 systems by using the intermediate exciton theory. We consider the C60-dimers, and the two (and three) molecule systems of the C60-polymers. We use a tight-binding model with long-range Coulomb interactions among electrons, and the model is treated by t

Joshua Goodman

Excellent results have been reported for Data-Oriented Parsing (DOP) of natural language texts (Bod, 1993). Unfortunately, existing algorithms are both computationally intensive and difficult to implement. Previous algorithms are expensive due to two factors: the exponential number of rules that must be generated and the use of a Monte Carlo parsing algorith

A. J. Roberts

I describe a method, particularly suitable to implementation by computer algebra, for the derivation of low-dimensional models of dynamical systems. The method is systematic and is based upon centre manifold theory. Computer code for the algorithm is relatively simple, robust and flexible. The method is applied to two examples: one a straightforward pitchfor

Wei Cui, Wilton T. Sanders, Dan McCammon, Steven L. Snowden

We observed several nearby face-on spiral galaxies with the ROSAT PSPC. The apparent deficiency in soft X-ray surface brightness observed at the outer portion of their disks is consistent with the absorption of the extragalactic soft X-ray background by material associated with these galaxies, and allows us to place a lower limit on the intensity of this cos

Wei Cui, Wilton T. Sanders, Dan McCammon, Steven L. Snowden

We observed several nearby face-on spiral galaxies with the ROSAT PSPC to study their 0.1-2.0 keV diffuse emission. After the exclusion of resolved discrete sources, there is unresolved X-ray emission in all the galaxies observed. Since this emission is a combination of diffuse emission and a contribution from unresolved point sources, it represents an upper

Christopher W. Churchill

HIRES/Keck spectra of Mg II (2796) absorption arising in the &#34;halos&#34; of 15 identified 0.4 < z < 0.9 galaxies are presented. Comparison of the galaxy and absorbing gas properties reveal that the spatial distribution of galactic/halo gas does not follow a smooth galactocentric dependence. The kinematics of absorbing gas in z < 1 galaxies are not sugges

William H. Press

To understand their data better, astronomers need to use statistical tools that are more advanced than traditional ``freshman lab&#39;&#39; statistics. As an illustration, the problem of combining apparently incompatible measurements of a quantity is presented from both the traditional, and a more sophisticated Bayesian, perspective. Explicit formulas are gi

Ralf Bender, Bodo Ziegler, Gustavo Bruzual

Velocity dispersions $σ$ and Mg absorption line-strengths Mg$_b$ have been measured for a sample of 16 ellipticals in 3 clusters at a redshift of 0.37. Like local cluster ellipticals, these objects show a correlation between Mg$_b$ and $σ$. However, at any given $σ$, the mean Mg$_b$ of the ellipticals at $z=0.37$ is weaker than the mean Mg$_b$ of their local

V. Burdyuzha, Yu. Ponomarev, O. Lalaculich, G. Vereshkov

We propose that the Universe was created from &#34;Nothing&#34; with a relatively small particles number and it very quick relaxed to quasiequilibrium state at the Planck parameters. The classic cosmological solution for this Universe, with the calculation of its ability to be undergo to the second order relativistic phase transition (RPT), has two branches

M. C. Ashworth

Coherent states possess a regularized path integral and gives a natural relation between classical variables and quantum operators. Recent work by Klauder and Whiting has included extended variables, that can be thought of as gauge fields, into this formalism. In this paper, I consider the next step, and look at the roll of first class constraints.

H. Lu, S. Mukherji, C. N. Pope amd J. Rahmfeld

It has recently been shown that for certain classical non-dilatonic $p$-branes, the entropy and temperature satisfy the ideal-gas relation $S\sim T^{p}$ in the near-extremal regime. We extend these results to cases where the dilaton is non-vanishing, but nevertheless remains finite on the horizon in the extremal limit, showing that the ideal-gas relation is

Victor Chernyak

The values of two important parameters of the heavy quark effective theory,\, $\bar Λ$ and $μ_π^2$ (the mean value of the heavy quark three momentum squared),\, have been determined recently in \cite {GKLW} from the precise CLEO data on the shape of the electron spectrum in semileptonic B meson decays. The values obtained in \cite{GKLW}: $\bar Λ=(0.55\pm 0.0

Heath B. O&#39;Connell

The topic of rho-omega mixing has received renewed interest in recent years and has been studied using a variety of modern techniques. A brief history of the subject is presented before summarising recent developments in the field. The present status of our understanding is discussed.

Olga Man&#39;ko

The marginal distribution of squeezed and rotated quadrature for two types of nonclassical states of trapped ion -- for squeezed and correlated states and for squeezed even and odd coherent states (squeezed Schrödinger cat states) is studied. The obtained marginal distribution for the two types of states is shown to satisfy classical dynamical equation equiv

Theodora Ioannidou

The behaviour of solitons in integrable theories is strongly constrained by the integrability of the theory; i.e. by the existence of an infinite number of conserved quantities which these theories are known to possess. One usually expects the scattering of solitons in such theories to be rather simple, i.e. trivial. By contrast, in this paper we generate ne

S. A. Gurvitz, A. Mair, M. Traini

Bjorken scaling is violetd. At large $x$-values ($0.7 \lesssim x \leq 1$) the violation is mainly attributed to $\propto 1/Q^2$ (higher-twist) corrections. We discuss how to incorporate such corrections by using a new scaling variable $\bar x(x,Q^2)$ which accounts for the non-perturbative effects due to the confining parton interaction in the final state. T

Richard Berkovits, Yshai Avishai

The statistical properties of spectra of a three-dimensional quantum bond percolation system is studied in the vicinity of the metal insulator transition. In order to avoid the influence of small clusters, only regions of the spectra in which the density of states is rather smooth are analyzed. Using finite size scaling hypothesis, the critical quantum proba

L. P. Horwitz, J. Levitan, Y. Ashkenazy

It is demonstrated in the context of the simple one-dimensional example of a barrier in an infinite well, that highly complex behavior of the time evolution of a wave function is associated with the almost degeneracy of levels in the process of tunneling. Degenerate conditions are obtained by shifting the position of the barrier. The complexity strength depe

J A Sellwood

Self-gravitating stellar disks with random motion support both exponentially growing and, in some cases, purely oscillatory axisymmetric bending modes, unlike their cold disk counterparts. A razor-thin disk with even a very small degree of random motion in the plane is both unstable and possesses a discrete spectrum of neutral modes, irrespective of the shar

Junichiro Kishine

We propose a possible mechanism of pseudo spin gap anomaly(PSGA) in magnetically coupled bi-layer cuprates without any fermion pairing instability. In our proposal PSGA does not necessarily require the spin-charge separation or the breakdown of the Fermi liquid description of a normal state of the cuprate superconductor.The low energy magnetic excitations ar

C. Brif, A. Mann, A. Vourdas

A parity-dependent squeezing operator is introduced which imposes different SU(1,1) rotations on the even and odd subspaces of the harmonic oscillator Hilbert space. This operator is used to define parity-dependent squeezed states which exhibit highly nonclassical properties such as strong antibunching, quadrature squeezing, strong oscillations in the photon

C. Brif, Y. Ben-Aryeh

We consider an SU(1,1) interferometer employing four-wave mixers that is fed with two-mode states which are both coherent and intelligent states of the SU(1,1) Lie group. It is shown that the phase sensitivity of the interferometer can be essentially improved by using input states with a large photon-number difference between the modes.

Doug Bullock

Let $M$ be a compact orientable 3-manifold. The set of characters of $SL_2({\mathbb C})$ representations of the fundamental group of $M$ forms a closed affine algebraic set. We show that its coordinate ring is isomorphic to a specialization of the Kauffman bracket skein module modulo its nilradical. This is accomplished by making the module into a combinator

Doug Bullock, Charles Frohman, Joanna Kania-Bartoszynska

The Kauffman bracket skein module $K(M)$ of a 3-manifold $M$ is defined over formal power series in the variable $h$ by letting $A=e^{h/4}$. For a compact oriented surface $F$, it is shown that $K(F \times I)$ is a quantization of the $\g$-characters of the fundamental group of $F$, corresponding to a geometrically defined Poisson bracket. Finite type invari

Takao Akahori

The purpose of this work is to propose a mixed Hodge structure over a CR manifold. As you know, for a CR manifold, Kohn-Rossi cohomology is naturally introduced. However, the relation between Kohn-Rossi cohomology and De Rham cohomology is not so well understood, even in Tanaka&#39;s work. We discuss this point.

Csaba Schneider

A nilpotent quotient algorithm for finitely presented Lie rings over Z (LieNQ) is described. The paper studies graded and non-graded cases separately. The algorithm computes the so-called nilpotent presentation for a finitely presented, nilpotent Lie ring. The nilpotent presentation consists of generators for the abelian group and the products---expressed as

M. Reuter

The conditions leading to a nontrivial renormalization of the topological charge in four--dimensional Yang--Mills theory are discussed. It is shown that if the topological term is regarded as the limit of a certain nontopological interaction, quantum effects due to the gauge bosons lead to a finite multiplicative renormalization of the theta--parameter while

P. Lipa, H. C. Eggers, B. Buschbeck

We review the basic notion of correlations in point processes, adapted to the language of high energy physicists. The measurement of accessible information on correlations by means of correlation integrals is summarized. Applications to the measurement of Bose-Einstein interferometry as well as some pitfalls are discussed.

P. Lipa, H. C. Eggers, B. Buschbeck

Factorial moments and cumulants are usually defined with respect to the unconditioned Poisson process. Conditioning a sample by selecting events of a given overall multiplicity $N$ necessarily introduces correlations. By means of Edgeworth expansions, we derive generalized cumulants which define correlations with respect to an arbitrary process rather than j

H. C. Eggers, C. Gale, R. Tabti, K. Haglin

The traditional calculation of dilepton yields from bremsstrahlung relies on the assumption that electromagnetic and strong processes factorize. We argue that this assumption, embodied by the soft photon approximation, cannot hold true for invariant mass spectra on very general grounds. Deriving a formula for the dilepton cross section for pion-pion scatteri

Bindu A. Bambah

Using the `quantum optical approach&#39; we propose a model of multiplicity distributions in high energy collisions based on squeezed coherent states. We show that the k-mode squeezed coherent state is the most general one in describing hadronic mulitiplicity distributions in particle collision processes, describing not only $p \bar p$ collisions but $e^{+}e

Alexei Yu. Smirnov, Morimitsu Tanimoto

Zee model leads naturally to two heavy, strongly degenerate and almost maximally mixed neutrinos and to one light neutrino with small mixing. This pattern coincides with the one needed for a solution of the atmospheric neutrino problem by $\n_\m\A \n_τ$ oscillations and for existence of the two component hot dark matter in the Universe. Furthermore, the osci

S. M. Bilenky, C. Giunti, C. W. Kim, S. T. Petcov

We have considered short-baseline neutrino oscillations, tritium beta-decay and neutrinoless double-beta decay in two schemes with an inverted mass spectrum and mixing of three and four massive neutrino fields. We have analyzed the results of the latest experiments on the search for oscillations of terrestrial neutrinos and we have discussed the compatibilit

A. Pajitnov

In this paper we continue the study of generic properties of the Novikov complex, began in the work &#34;The incidence coefficients in the Novikov complex are generically rational functions&#34; ( dg-ga/9603006). For a Morse map $f:M\to S^1$ there is a refined version of Novikov complex, defined over the Novikov completion of the fundamental group ring. We p

Steven R. White

I report results of a density matrix renormalization group (DMRG) study of a model for the two dimensional spin-gapped system CaV$_4$O$_9$. This study represents the first time that DMRG has been used to study a two dimensional system on large lattices, in this case as large as $24\times 11$, allowing extrapolation to the thermodynamic limit. I present a sub

Brian Chaboyer, Pierre Demarque, Peter Kernan, Lawrence M. Krauss

Globular cluster age estimates based on the absolute magnitude of the main sequence turn-off (\mvto) are generally considered to be the most reliable from a theoretical viewpoint. However, the difficulty in determining \mvto\ in observed colour-magnitude diagrams leads to a large error in the derived age. In this paper, we advocate the use of the absolute ma

Nathan Berkovits

This is a review of the new manifestly spacetime-supersymmetric description of the superstring. The new description contains N=2 worldsheet supersymmetry, and is related by a field redefinition to the standard RNS description. It is especially convenient for four-dimensional compactifications since SO(3,1) super-Poincaré invariance can be made manifest. Part

Seth Lloyd

An upper limit is given to the amount of quantum information that can be transmitted reliably down a noisy, decoherent quantum channel. A class of quantum error-correcting codes is presented that allow the information transmitted to attain this limit. The result is the quantum analog of Shannon&#39;s bound and code for the noisy classical channel.

Jun Hu, E. Dagotto, A. H. MacDonald

We study the ground state and the collective excitations of parabolically-confined double-layer quantum dot systems in a strong magnetic field. We identify parameter regimes where electrons form maximum density droplet states, quantum-dot analogs of the incompressible states of the bulk integer quantum Hall effect. In these regimes the Hartree-Fock approxima

Michael B. Green, Christopher M. Hull, Paul K. Townsend

A geometrical formulation of the T-duality rules for type II superstring Ramond--Ramond fields is presented. This is used to derive the Wess-Zumino terms in superstring D-brane actions, including terms proportional to the mass parameter of the IIA theory, thereby completing partial results in the literature. For non-abelian world-volume gauge groups the mass

B. Mobasher, M. Rowan-Robinson, A. Georgakakis, N. Eaton

We present a study of the galaxies found in the Hubble Deep Field. A high proportion of HDF galaxies are undergoing a strong episode of star formation, as evidenced by their very blue colours. A wide range of morphological types is found, with a high proportion of peculiar and merger morphologies. Fitting the multiband spectra with redshifted SEDs of galaxy

A. V. Smilga

In this lecture, we give a brief review of what theorists now know, understand, or guess about static and kinetic properties of quark--gluon plasma. A particular attention is payed to the problem of physical observability, i.e. the physical meaningfulness of various characteristics of $QGP$ discussed in the literature.

D. V. Shirkov, I. L. Solovtsov

As is known from QED, a possible solution to the ghost-pole trouble can be obtained by imposing the $Q^2$-analyticity imperative. Here, the pole is compensated by the $α$ non-analytic contribution that results in finite coupling renormalization. We apply this idea to QCD and arrive at the $Q^2$ analytic $\barα_s(Q)$. This solution corresponds to perturbation

Naoyuki Haba

We show a new and simple model which induces large Majorana masses of right-handed neutrinos. It is based on U(1)_X anomalous gauge symmetry, which is cancelled by the Green-Schwarz mechanism. These Majorana masses can solve the solar neutrino problem by the vacuum oscillation mechanism. The superpotential of this model is scale invariant. The field contents

Igor Pris, Thomas Schucker

A natural extension of the standard model within non-commutative geometry is presented. The geometry determines its Higgs sector. This determination is fuzzy, but precise enough to be incompatible with experiment.

Kazuo Fujikawa

Physical implications of a vector-like extension of the standard model for heavier quarks and leptons with $SU(2)\times U(1)$ gauge symmetry and only one Higgs doublet are discussed. This scheme incorporates infinitely many fermions, and the chiral structure is realized by a non-vanishing analytic index of mass matrices. The model is perturbatively well cont

Keith R. Dienes, John March-Russell

We consider the methods by which higher-level and non-simply laced gauge symmetries can be realized in free-field heterotic string theory. We show that all such realizations have a common underlying feature, namely a dimensional truncation of the charge lattice, and we identify such dimensional truncations with certain irregular embeddings of higher-level an

T. Goldman

A description of neutrino oscillation phenomena is presented which is based on relativistic quantum mechanics and includes both entangled state and source dependent aspects, unlike both of the conventional approaches which use either equal energies or equal momenta for the different neutrino mass eigenstates. To second order in the neutrino masses, the stand

Indranil Dasgupta

We explore the viability of baryogenesis from light scalar decays after the electroweak phase transition. A minimal model of this kind is constructed with new CP violating interactions involving a heavy fourth family. The departure from thermal equilbrium must come from topological defects like cosmic strings, and we show that almost any mechanism for produc

D. Gordon, C. M. Savage

Diffraction of multi-level atoms by an evanescent wave reflective diffraction grating is modeled by numerically solving the time-dependent Schrödinger equation. We are able to explain the diffraction observed in experiments with metastable Neon. This is not possible using a two-level atom model. The multi-level model predicts sensitive dependence of diffract

Takashi Takebe

A higher spin generalization of the XYZ spin chain defined by the fusion procedure is considered. Energy and momentum of the ground state and low-lying excited states of the model are computed by means of an isomorphism between a space of theta functions on which the Sklyanin algebra acts and a space obtained by the fusion procedure.

W. M. Kloet, F. Myhrer

A simple partial wave amplitude analysis of $\overline{p}p \rightarrow K^-K^+$ has been performed for data in the range $p_{\rm lab}$ = 360 -- 1000 MeV/$c$. In this low momentum interval only partial wave amplitudes with $J$ equal to 0, 1 and 2 are needed to obtain a good fit to the experimental data. This maximal $J$ = 2 value is smaller than what is requir

Alastair M. Rucklidge

Convection in an infinite fluid layer is often modelled by considering a finite box with periodic boundary conditions in the two horizontal directions. The translational invariance of the problem implies that any solution can be translated horizontally by an arbitrary amount. Some solutions travel, but those solutions that are invariant under reflections in

James D. Meiss

For a volume preserving map, the exit time, averaged over the incoming set of a region, is given by the ratio of the measure of the accessible subset of the region to that of the incoming set. This result is primarily of interest to show two things: first it gives a simple bound on the algebraic decay exponent of the survival probability. Second, it gives a

George Androulakis, Edward Odell

Any regular mixed Tsirelson space $T(θ_n,S_n)_{\N}$ for which $\frac{θ_n}{θ^n} \to 0$, where $θ=\lim_n θ_n^{1/n}$, is shown to be arbitrarily distortable. Certain asymptotic $\ell_1$ constants for those and other mixed Tsirelson spaces are calculated. Also a combinatorial result on the Schreier families $(S_α)_{α< ω_1}$ is proved and an application is given

B. Dey, Avinash Khare C. Nagaraja Kumar

Exact stationary soliton solutions of the fifth order KdV type equation $$ u_t +αu^p u_x +βu_{3x}+γu_{5x} = 0$$ are obtained for any p ($>0$) in case $αβ>0$, $Dβ>0$, $βγ<0$ (where D is the soliton velocity), and it is shown that these solutions are unstable with respect to small perturbations in case $p\geq 5$. Various properties of these solutions are discu

Nathan Berkovits

We point out that off-shell four-dimensional supersymmetry implies strange hermiticity properties for the N=1 RNS superstring. However, these hermiticity properties become natural when the N=1 superstring is embedded into an N=2 superstring.

Nathan Berkovits

The new spacetime-supersymmetric description of the superstring is used to compute tree-level scattering amplitudes for an arbitrary number of massless four-dimensional states. The resulting Koba-Nielsen formula is manifestly SO(3,1) super-Poincare invariant and is easily generalized to scattering in the presence of a D-brane.

D. V. Boulatov

A quantum deformation of 3-dimensional lattice gauge theory is defined by applying the Reshetikhin-Turaev functor to a Heegaard diagram associated to a given cell complex. In the root-of-unity case, the construction is carried out with a modular Hopf algebra. In the topological (weak-coupling) limit, the gauge theory partition function gives a 3-fold invaria

Geoffrey Dixon

The automorphism group $G_{2}$ of the octonions changes when octonion X,Y-product variants are used. I present here a general solution for how to go from $G_{2}$ to its X,Y-product variant.

M. Bonini, G. Marchesini, M. Simionato

We discuss the relation between the Gell-Mann-Low beta function and the ``flowing couplings&#39;&#39; of the Wilsonian action $S_Ł[ϕ]$ of the exact renormalization group (RG) at the scale $Ł$. This relation involves the ultraviolet region of $Ł$ so that the condition of renormalizability is equivalent to the Callan-Symanzik equation. As an illustration, by u

P. M. Lavrov, P. Yu. Moshin

The structure of state vector space for a general (non-anomalous) gauge theory is studied within the Lagrangian version of the $Sp(2)$-symmetric quantization method. The physical {\it S}-matrix unitarity conditions are formulated. The general results are illustrated on the basis of simple gauge theory models.

N. Gurappa, C. Nagaraja Kumar, Prasanta. K. Panigrahi

We study a class of Calogero-Sutherland type one dimensional N-body quantum mechanical systems, with potentials given by $$ V( x_1, x_2, \cdots x_N) = \sum_{i <j} {g \over {(x_i - x_j)^2}} - \frac{g^{\prime}}{\sum_{i<j}(x_i - x_j)^2} + U(\sqrt{\sum_{i<j}(x_i - x_j)^2}),$$ where $U(\sqrt{\sum_{i<j}(x_i - x_j)^2})$&#39;s are of specific form. It is shown that,

S. Gavin, P. L. McGaughey, P. V. Ruuskanen, R. Vogt

Measurements of dilepton production from charm decay and Drell-Yan processes respectively probe the gluon and sea quark distributions in hadronic collisions. In nucleus-nucleus collisions, these hard scattering processes constitute a `background&#39; to thermal contributions from the hot matter produced by the collision. To determine the magnitude and behavi

Alan Chodos

The phenomenon of sonoluminescence (SL), originally observed some sixty years ago, has recently become the focus of renewed interest, particularly with the discovery that one can trap a single bubble and induce it to exhibit SL stably over a large number of acoustical cycles. In this work we shall adopt a version of the provocative suggestion put forward by

A. Bialas, B. Ziaja

The possibility to study intermittency in a single event of high multiplicity is investigated in the framework of the $α-$model. It is found that, for cascade long enough, the dispersion of intermittency exponents obtained from individual events is fairly small. This fact opens the possibility to study the distribution of the intermittency parameters charact

Uma Mahanta

In this article we show that the $\rb -\als $ crisis of the SM can be resolved in a commuting TC scenario with sideways gauge bosons only if the ETC representation contains mirror technifermions. For a toy ETC model we estimate the value of $ξ^2_t={\gel/ \guer}$ that is needed to produce the observed LEP excess in $\rb$. It is also shown that the same value

Andrea Romanino

Intrinsic EDMs in microscopic systems at a level of sensitivity achievable in experiments under way or foreseen are predicted in supersymmetric unified theories. I describe this and other sources of measurable EDMs and I show how these sources can be distinguished through experiments in different systems.

J. Ellis, G. Ross

We discuss whether the diffractive structure functions defined by current experiments at HERA are indeed probing the partonic structure function of the pomeron. We observe that the {\it pseudorapidity} cuts commonly employed require that the struck parton in the pomeron be far off mass shell in sizeable regions of parameter space. As a result an interpretati

S. V. Goloskokov

We study the contribution of diffractive $Q \bar Q$ production to the $F_2^D$ proton structure function and the longitudinal double-spin asymmetry in polarized deep--inelastic $lp$ scattering. We show the strong dependence of the $F_2^D$ structure function and the $A_{ll}$ asymmetry on the quark--pomeron coupling structure.

H. Kawai, N. Tsuda, T. Yukawa

Complex structures are determined for surfaces with $S^2$ and $T^2$ topologies generated by the dynamical triangulation method. For a surface with $S^2$ topology the spacial distribution of the conformal mode is obtained, while for the case of $T^2$ topology the distribution of the moduli parameter is calculated. It is also shown that the network of Feynman

V. A. Rubakov, O. Yu. Shvedov

Wormholes -- solutions to the euclidean Einstein equations with non-trivial topology -- are usually assumed to make real contributions to amplitudes in quantum gravity. However, we find a negative mode among fluctuations about the Giddings-Strominger wormhole solution. Hence, the wormhole contribution to the euclidean functional integral is argued to be pure

C. L. Emmott, A. J. Bray

We study the one-dimensional Cahn-Hilliard equation with an additional driving term representing, say, the effect of gravity. We find that the driving field $E$ has an asymmetric effect on the solution for a single stationary domain wall (or `kink&#39;), the direction of the field determining whether the analytic solutions found by Leung [J.Stat.Phys.{\bf 61

S. Y. Savrasov

A detailed description of a method for calculating static linear-response functions in the problem of lattice dynamics is presented. The method is based on density functional theory and it uses linear muffin-tin orbitals as a basis for representing first-order corrections to the one-electron wave functions. As an application we calculate phonon dispersions i

S. Y. Savrasov, D. Y. Savrasov

Spectral distribution functions of electron-phonon interaction $α^2F(ω)$ obtained by ab initio linear--response calculations are used to describe various superconducting and transport properties in a number of elemental metals such as Al,Cu,Mo,Nb,Pb,Pd,Ta, and V. Their lattice dynamics and self-consistently screened electron-phonon coupling are evaluated wit

Daniel A. Hamburger, Ofer Biham, David Avnir

The fractal properties of models of randomly placed $n$-dimensional spheres ($n$=1,2,3) are studied using standard techniques for calculating fractal dimensions in empirical data (the box counting and Minkowski-sausage techniques). Using analytical and numerical calculations it is shown that in the regime of low volume fraction occupied by the spheres, appar

Robert John Freeman

A perspective of statistical language models which emphasizes their collocational aspect is advocated. It is suggested that strings be generalized in terms of classes of relationships instead of classes of objects. The single most important characteristic of such a model is a mechanism for comparing patterns. When patterns are fully generalized a natural def

D. A. Frail, E. B. Giacani, W. M. Goss, G. Dubner

We present radio observations of a region in the vicinity of the young pulsar PSR B1853+01 in the supernova remnant W44. The pulsar is located at the apex of an extended feature with cometary morphology. We argue on the basis of its morphology and its spectral index and polarization properties that this is a synchrotron nebula produced by the spin down energ

Ilana M. Harrus, John P. Hughes, David J. Helfand

We report the detection using ASCA data of a hard X-ray source in the vicinity of the radio pulsar PSR B1853+01 which is located within the supernova remnant (SNR) W44. PSR B1853+01, a 267ms pulsar, has to date only been detected in the radio band. Previous observations at soft X-ray energies (e.g., with ROSAT HRI) have failed to detect any significant X-ray

Lori M. Lubin

We present a color analysis of the galaxy populations of candidate clusters of galaxies from the Palomar Distant Cluster Survey (Postman et al.\ 1996). The survey was conducted in two broad band filters that closely match $V$ and $I$ and contains a total of 79 candidate clusters of galaxies, covering an estimated redshift range $0.2 \simless z \simless 1.2$.

D. G. Yakovlev, A. D. Kaminker

Neutrino-pair bremsstrahlung radiation is considered due to electron--phonon scattering of degenerate, relativistic electrons in a lattice of spherical atomic nuclei in a neutron star crust. The neutrino energy generation rate is calculated taking into account exact spectrum of phonons, the Debye--Waller factor, and the nuclear form--factor in the density ra

Marina Gibilisco

The quantum evaporation of primordial black holes may have a relevant effect on the reionization of the Universe at small redshifts ($z \leq 60$): in this paper, I studied the possibility of a reionization induced by the photons emitted during the last stages of the black holes life. I also took into account the quark and gluons jets production, that sensibl

Yu. A. Shibanov, D. G. Yakovlev

Cooling of neutron stars with dipole magnetic fields is simulated using a realistic model of the anisotropic surface temperature distribution produced by magnetic fields. Suppression of the electron thermal conductivity of outer stellar layers across the field increases thermal isolation of these layers near the magnetic equator. Enhancement of the radiative

Nicole P. Vogt, Terry Herter, Martha P. Haynes, Stephane Courteau

We have undertaken a pilot project to measure the rotation velocities of spiral galaxies in the redshift range 0.18 < z < 0.4 using high dispersion long slit spectroscopy obtained with the Palomar 5m telescope. One field galaxy and three cluster objects known to have strong emission lines were observed over wavelength ranges covering the redshifted lines of

David C. Koo, Nicole P. Vogt, Andrew C. Phillips, Rafael Guzman

We report results based on 35 new spectroscopic redshifts obtained with the Keck Telescope for field galaxies that also have photometry and morphology from survey images taken by the refurbished HST. A sample of 24 redshifts for galaxies fainter than I = 22 has a median redshift of z ~ 0.81. This result is inconsistent with the lower median redshift of z ~ 0

Hiromichi Takagi

We classify extremal divisorial contraction which contracts a divisor to a curve from a smooth fourfold. We prove the exceptional divisor is $\Bbb P^2$bundle or quadric bundle over a smooth curve and the contraction is the blowing up along the curve.

N. Lauritzen, A. P. Rao

We give elementary counterexamples to Kodaira vanishing in prime characteristic constructed as the projectivization of Frobenius pull-backs of natural bundles on the incidence variety of points and planes in projective n-space (n>2).

Vitaly Tarasov, Alexander Varchenko

The rational quantized Knizhnik-Zamolodchikov equation (qKZ equation) associated with the Lie algebra $sl_2$ is a system of linear difference equations with values in a tensor product of $sl_2$ Verma modules. We solve the equation in terms of multidimensional $q$-hypergeometric functions and define a natural isomorphism between the space of solutions and the

David W. Hogg, Roger Blandford, Tomislav Kundić, C. D. Fassnacht

The discovery of HDF~J123652+621227, a candidate gravitational lens in the HDF, is reported. This lens may be multiply imaging several optical sources at different redshifts. If follow-up spectroscopy of the lens and the brightest image confirms this hypothesis, observations of this system alone can be used to obtain an estimate of the redshift distribution

Robert B. Mann, Sergey N. Solodukhin

We apply the method of conical singularities to calculate the tree-level entropy and its one-loop quantum corrections for a charged Kerr black hole. The Euclidean geometry for the Kerr-Newman metric is considered. We show that for an arbitrary periodization in Euclidean space there exists a conical singularity at the horizon. Its $δ$-function like curvatures

S. Dawson, H. Haber

In order to extend the Standard Model to TeV scale energies one must address two basic questions: (1) What is the complete description of the effective theory of fundamental particles at and below the electroweak scale? and (2) What is the dynamics responsible for electroweak symmetry breaking? The answers to these questions are crucial for addressing the th

A M Semikhatov

Any non-critical N=2 string is shown to have an affine sl(2|1) worldsheet symmetry in the conformal gauge.

B. A. Bassett

We provide analytical functions approximating $\int e^{-x^2} dx$, the basis of which is the kink soliton and which are both accurate (error $< 0.2 %$) and simple. We demonstrate our results with some applications, particularly to the generation of Gaussian random fields.

Alexei L. Gorodentsev, Maxim I. Leyenson

We explain how to calculate the correlation function for SYM N=2 SO(3)-gauge QFT with 4 flavors in terms of top Chern classes of the universal bundles over the moduli spaces of rank 2 stable torsion free coherent sheaves with det=-1 on the complex projective plane. We give a direct geometrical description of these moduli spaces, study a 2-dimensional torus a