July 1996 arXiv papers — page 2

T. K. Ng, C. M. Varma

It is argued that a spontaneous vortex phase may exist in the recently discovered compound $ErNi_2B_2C$ at temperature below 2.3K. The consequences of this proposal are discussed. In particular the magnetic response of the system are studied both above and below 2.3K and further experiments proposed.

Tai-Kai Ng

In this paper we study in a large-S expansion effects of substituting spins by non-magnetic impurities in two- and three- dimensional Heisenberg antiferromagnets in a weak magnetic field. In particular, we demonstrate a novel mechanism where magnetic moments are induced around non-magnetic impurities when magnetic field is present. As a result, Curie-type be

G. E. Volovik

Many direct parallels connect superfluid 3He with the field theories describing the physical vacuum, gauge fields and elementary fermions. Superfluid $^3$He exhibits a variety of topological defects which can be detected with single-defect sensitivity. Modern scenarios of defect-mediated baryogenesis can be simulated by the interaction of the 3He vortices an

Stéphane Ferrari

In this paper, we propose a textual clue approach to help metaphor detection, in order to improve the semantic processing of this figure. The previous works in the domain studied the semantic regularities only, overlooking an obvious set of regularities. A corpus-based analysis shows the existence of surface regularities related to metaphors. These clues can

Yoshiki Mori

In the German government (BMBF) funded project Verbmobil, a semantic formalism Language for Underspecified Discourse Representation Structures (LUD) is used which describes several DRSs and allows for underspecification. Dealing with Japanese poses challenging problems. In this paper, a treatment of multiple discourse relation constructions on the sentential

Johannes Heinecke, Karsten L. Worm

This paper describes the development and use of a lexical semantic database for the Verbmobil speech-to-speech machine translation system. The motivation is to provide a common information source for the distributed development of the semantics, transfer and semantic evaluation modules and to store lexical semantic information application-independently. The

Johan Bos, Björn Gambäck, Christian Lieske, Yoshiki Mori

The paper discusses how compositional semantics is implemented in the Verbmobil speech-to-speech translation system using LUD, a description language for underspecified discourse representation structures. The description language and its formal interpretation in DRT are described as well as its implementation together with the architecture of the system&#39

Gokhan Tur

This thesis presents a constraint-based morphological disambiguation approach that is applicable to languages with complex morphology--specifically agglutinative languages with productive inflectional and derivational morphological phenomena. For morphologically complex languages like Turkish, automatic morphological disambiguation involves selecting for eac

Dilek Zeynep Hakkani

This thesis describes a tactical generator for Turkish, a free constituent order language, in which the order of the constituents may change according to the information structure of the sentences to be generated. In the absence of any information regarding the information structure of a sentence (i.e., topic, focus, background, etc.), the constituents of th

V. A. Lipovetsky, F. Chaffee, C. Foltz, Yu. I. Izotov

We present Multiple Mirror Telescope (MMT) spectrophotometry and 3.5m Calar Alto telescope R, I photometry of the western component of the extremely low-metallicity blue compact galaxy SBS 0335-052. We argue that both components, separated by 24 kpc, are members of an unique, physically connected system. It is shown that SBS 0335-052W has the same redshift a

E. E. Fenimore, Claudine Madras, Sergei Nayakshin

Many models of cosmological gamma-ray bursts involve the sudden release of $\sim 10^{51}$ erg which produce shells which expand at relativistic speeds (Lorentz $Γ$ factors of $10^{2-3}$). We investigate the kinematic limits on the source size due to the observed time structure in three types of bursts: short spikes, FREDs (Fast Rise, Exponentail decay), and

Richard Pogge

Representative results of a search for structures suggestive of shocked gas in the circumnuclear regions of Seyfert galaxies are presented. At issue is whether we can identify regions that appear to be shocked by outflows from the active nucleus. Such regions will be good targets for future spectrophotometric studies to determine what role shocks play in the

Gerald H. Moriarty-Schieven, Harold M. Butner

We have monitored the millimeter and submillimeter emission from the young stellar object GG Tau, a T Tauri binary system surrounded by a massive circumbinary disk. We find that between 1992 and 1994, the flux has increased significantly at 800, 1100, and 1300 microns, resulting in a steepening of the observed spectral energy distribution at those wavelength

B. Kuhlman, A. L. Melott, S. F. Shandarin

We present results of tests of the evolution of small ``fluid elements'' in cosmological N--body simulations, to examine the validity of their treatment as particles. We find that even very small elements typically collapse along one axis while expanding along another, often to twice or more their initial comoving diameter. This represents a possible

G. F. Marani, R. J. Nemiroff, J. P. Norris, J. T. Bonnell

Recent claims of angular correlations between gamma-ray bursts (GRBs) and clusters of galaxies are evaluated in light of existing but previously uncorrelated GRB positional data. Additional GRB data sets we use include sub-samples of soft BATSE 3B bursts, bursts located by the Interplanetary Network (IPN), and GRBs localized by COMPTEL. We confirm a previous

Attilio Cucchieri, Daniel Zwanziger

The static color-Coulomb interaction potential is calculated as the solution of a non-linear integral equation which arises in the Hamiltonian Coulomb gauge when the restriction to the interior of the Gribov horizon is implemented. The potential obtained is in qualitative agreement with expectations, being Coulombic with logarithmic corrections at short rang

Sergio Gelato, David F. Chernoff, Ira Wasserman

This article describes a new, fully adaptive Particle-Multiple-Mesh numerical simulation code developed primarily for simulations of small regions (such as a group of galaxies) in a cosmological context. It integrates the equations of motion of a set of particles subject to their mutual gravitational interaction and to an arbitrary external field. The intera

Richard S. Ellis, Ian Smail, Alan Dressler, Warrick J. Couch

The small scatter observed for the U-V colors of spheroidal galaxies in nearby clusters of galaxies provides a powerful constraint on the history of star formation in dense environments. However, with local data alone, it is not possible to separate models where galaxies assembled synchronously over redshifts 0<z<1 from ones where galaxies formed stochastica

A. M. Tsvelik

We consider conditions for existence of fermionic quasiparticles in a strongly anisotropic quasi-one-dimensional metal. The adopted model is a model of chains of spin-1/2 Luttinger liquid coupled by small interchain hopping. It is shown that the Luttinger liquid becomes more stable with decrease of the lattice coordination number. It is also shown that with

Paul J. Francis

Quasi-simultaneous optical/near-IR photometry is presented for a sample of 37 luminous optically selected QSOs drawn from the Large Bright QSO Survey. Most of the QSOs have decreased in brightness since discovery; this is expected in flux-limited samples. The continuum shape of most of the QSOs can be represented by a power-law of the form F(nu) = nu**-0.3,

I. L. Buchbinder, A. Yu. Petrov

A general structure of effective action in new chiral superfield model associated with $N=1$, $D=4$ supergravity is investigated. This model corresponds to finite quantum field theory and does not demand the regularization and renormalization at effective action calculation. It is shown that in local approximation the effective action is defined by two objec

Daya M. Rawson, Jeremy Bailey, Paul J. Francis

The use of Artificial Neural Networks (ANNs) as a classifier of digital spectra is investigated. Using both simulated and real data, it is shown that neural networks can be trained to discriminate between the spectra of different classes of active galactic nucleus (AGN) with realistic sample sizes and signal-to-noise ratios. By working in the Fourier domain,

Lov K. Grover

Consider the problem of estimating the median of N items to a precision epsilon, i.e., the estimate should be such that, with a high probability, the number of items, with values both smaller than and larger than this estimate, is less than N*(1+epsilon)/2. Any classical algorithm to do this will need at least O(1/epsilon^2) samples. Quantum mechanical syste

Tchavdar D. Palev

A description of the orthosymplectic Lie superalgebra $osp(2n+1/2m)$ and also of its $q-$deformed analogue $U_q[osp(2n+1/2m)]$ in terms of a new set of generators, called Green generators, is given. These generators are very different form the well known Chevalley generators. Mathematically the Green generators are the root vectors, corresponding to the posi

S. Zakrzewski

Natural conditions on a Poisson/quantum group G to implement Poisson/quantum gauge transformations on the lattice are investigated. In addition to our previous result that transformations on one lattice link require G to be coboundary, it is shown that for a sequence of links one needs a quasitriangular G.

Alain Karma, Wouter-Jan Rappel

Dendritic crystal growth in a pure undercooled melt is simulated quantitatively in three dimensions using a phase-field approach. The full non-axisymmetric morphology of the steady-state dendrite tip and $σ^*$ are determined as a function of anisotropy for a crystal with a cubic symmetry. Results are compared to experiment and used to critically test solvabi

W. E. Ormand, P. F. Bortignon, R. A. Broglia, A. Bracco

The properties of the giant-dipole resonance (GDR) are calculated as a function of excitation energy, angular momentum, and the compound nucleus particle decay width in the nuclei $^{120}$Sn and $^{208}$Pb, and are compared with recent experimental data. Differences observed in the behavior of the full-width-at-half-maximum of the GDR for $^{120}$Sn and $^{2

Joe Kamimoto

The CR manifold M_m = { Im z_2= Re z_1^{2m} } (m=2,3,...) is the counterexample, which has been given by M. Christ and D. Geller, to analytic hypoellipticity of d-bar-b and real analyticity of the Szego kernel. In order to give a direct interpretation for the breakdown of real analyticity of the Szego kernel, we give a Borel summation type representation of

Soonkeon Nam

There is a close relation between duality in $N=2$ SUSY gauge theories and integrable models. In particular, the quantum moduli space of vacua of $N=2$ SUSY $SU(3)$ gauge theories coupled to two flavors of massless quarks in the fundamental representation can be related to the spectral curve of the Goryachev-Chaplygin top. Generalizing this to the cases with

Tchavdar D. Palev

The known Holstein-Primakoff and Dyson realizations for the Lie algebras $gl(n+1),\;n=1,2,\ldots$ in terms of Bose operators are generalized to the class of the Lie superalgebras $gl(m/n+1)$ for any $n$ and $m$. Formally the expressions are the same as for $gl(m+n+1)$, however both Bose and Fermi operators are involved.

Tchavdar D. Palev

An analogue of the Holstein-Primakoff and of the Dyson realization for the Lie superalgebra $sl(1/n)$ is written down. The expressions are formally the same as for the Lie algebra $sl(n+1)$, however in the latter the Bose operators have to be replaced with Fermi operators.

R. S. Dunne, A. J. Macfarlane, J. A. de Azcárraga, J. C. Pérez Bueno

We show that one-dimensional superspace is isomorphic to a non-trivial but consistent limit as $q\to-1$ of the braided line. Supersymmetry is identified as translational invariance along this line. The supertranslation generator and covariant derivative are obtained in the limit in question as the left and right derivatives of the calculus on the braided lin

Robert Carroll

Some formulas and speculations are presented relative to integrable systems and quantum mechanics.

Ingo Gaida

Global N=2 supersymmetry in four dimensions with a Fayet-Sohnius hypermultiplet and a complex central charge is studied in N = 2 superspace. It is shown how to construct the complete expansion of the hypermultiplet with respect to the central charge. In addition the low-energy effective action is discussed and it is shown that the `kernel&#39; of the Lagrang

Jordi París, Walter Troost

An algebraic program of computation and characterization of higher loop BRST anomalies is presented. We propose a procedure for disentangling a genuine{\it local} higher loop anomaly from the quantum dressings of lower loop anomalies. For such higher loop anomalies we derive a local consistency condition, which is the generalisation of the Wess-Zumino condit

Giovanni Salesi, Erasmo Recami

Starting from the formal expressions of the hydrodynamical (or ``local&#39;&#39;) quantities employed in the applications of Clifford Algebras to quantum mechanics, we introduce --in terms of the ordinary tensorial framework-- a new definition for the field of a generic quantity. By translating from Clifford into tensor algebra, we also propose a new (non-re

Giovanni Salesi, Erasmo Recami

Inserting the correct Lorentz factor into the definition of the 4-velocity v^mu for spinning particles entails new kinematical properties for v^2. The well-known constraint (identically true for scalar particles, but entering also the Dirac theory, and assumed a priori in all spinning particle models) p_mu v^mu = m is here derived in a self-consistent way.

Giovanni Salesi, Erasmo Recami

One of the most satisfactory pictures for spinning particles is the Barut-Zanghi (BZ) classical theory for the relativistic extended-like electron, that relates spin to zitterbewegung (zbw). The BZ motion equations constituted the starting point for recent works about spin and electron structure, co-authored by us, which adopted the Clifford algebra language

Giovanni Salesi, Erasmo Recami

We present here a field theory of the spinning electron, by writing down a new equation for the 4-velocity field v^mu (different from that of Dirac theory), which allows a classically intelligible description of the electron. Moreover, we make explicit the noticeable kinematical properties of such velocity field (which also result different from the ordinary

Csaba Csaki, Witold Skiba, Martin Schmaltz

We study supersymmetric Sp(2N) gauge theories with matter in the antisymmetric tensor representation and F fundamentals. For F=6 we solve the theory exactly in terms of confined degrees of freedom and a superpotential. By adding mass terms we obtain the theories with F<6 which we find to exhibit a host of interesting non-perturbative phenomena: quantum defor

Howard Baer, Michal Brhlik, Diego Castano

We evaluate regions of parameter space in the minimal supergravity model where ``unbounded from below&#39;&#39; (UFB) or charge or color breaking minima (CCB) occur. Our analysis includes the most important terms from the 1-loop effective potential. We note a peculiar discontinuity of results depending on how renormalization group improvement is performed: O

Junegone Chay, Stephen D. Ellis

The structure of hadronic jets depends not only on the dynamics of QCD but also on the details of the jet finding algorithm and the physical process in which the jet is produced. To study these effects in more detail we calculate the jet cross section and the internal jet structure in e+e- annihilations and compare them to the results found in hadronic colli

Nima Arkani-Hamed, Hsin-Chia Cheng, Takeo Moroi

The gaugino mass relations $m_3/{g_3^2} = m_2/{g_2^2} = m_1/{g_1^2}$ are considered to be robust signals for supersymmetric grand unification. In this letter, we point out that these relations may be significantly modified in an interesting class of models which solve the doublet-triplet splitting problem using a missing partner mechanism together with a str

J. Bijnens, P. Gosdzinsky

We use the 1/N_c method to estimate electromagnetic contributions to vector meson masses and mixings. We identify several new sources of rho-omega mixing coming from short-distance effects. We comment on the extraction of quark masses from the vector meson masses. We also present a simple group theoretical discussion of the electromagnetic mass differences.

K. Harayama, N. Okamura, A. I. Sanda, Z. Z. Xing

We present a class of Ansatze for the up and down quark mass matrices which leads approximately to: |V_{us}| \sim \sqrt{m_d / m_s}, |V_{cb}| \sim m_s / m_b, and |V_{ub} / V_{cb}| \sim \sqrt{m_u / m_c}. Sizes of the Kobayashi-Maskawa matrix elements are controlled solely by quark mass ratios. In particular, we introduce no other small parameter and our result

Ll. Ametller, Ll. Garrido, P. Talavera

We consider the possibility of using neural networks in experimental data analysis in Daphne. We analyze the process $γγ\to π^+ π^- π^0$ and its backgrounds using neural networks and we compare their performances with traditional methods of applying cuts on several kinematical variables. We find that the neural networks are more efficient and can be of great

N. Kaiser, T. Waas, W. Weise

We identify the leading s-wave amplitudes of the SU(3) chiral meson-baryon Lagrangian with an effective coupled-channel potential which is iterated in a Lippmann-Schwinger equation. The strangeness $S=-1$ resonance $Λ(1405)$ and the $S_{11}(1535)$ nucleon resonance emerge as quasi-bound states of anti-kaon/nucleon and kaon/$Σ$-hyperon. Our approach to meson

Richard Dawid, Serguei Reznov

The possibilities for an underlying theory behind an effective supersymmetric Nambu--Jona-Lasinio like model of electroweak symmetry breaking with propagating Higgs boundstates (e.g. supersymmetric topcondensation) are investigated. The concept of a renormalizable underlying theory turns out not to be appropriate. We argue that the new theory should come fro

A. Barducci, R. Casalbuoni, R. Gatto, M. Modugno

We perform a 1/N-expansion of the partition function of the massive Gross-Neveu model in 1+1 dimensions. The procedure allows for the inclusion of the contribution of scalar and pseudoscalar composites (of order 1/N) to the equation of state. The naive expectation that the bosonic fluctuations correct significantly the mean field approximation at low tempera

Y. B. He, W. Q. Chao, C. S. Gao, X. Q. Li

We have studied the phase diagram and evolution of a strangelet in equilibrium with a finite hadronic gas. Significant finite size modifications of the phase diagram are found and their parameter dependences are studied. With the inclusion of finite size effects we have also been able to obtain the detailed properties of the cold strangelet emerging in the f

K. Bernstein, G. Di Cecio, R. W. Haymaker

We study dual Abrikosov vortices in Abelian projected SU(2) gauge theory in the Polyakov gauge. We show that vortices are present in this gauge but they are suppressed with respect to the maximal Abelian gauge. We interpret this difference in terms of the shielding of the electric charge by the charged coset fields.

Ray L. Renken

A block spin renormalization group approach is proposed for the dynamical triangulation formulation of quantum gravity in arbitrary dimensions. Renormalization group flow diagrams are presented for the three-dimensional and four-dimensional theories near their respective transitions.

Pietro Menotti, Pier Paolo Peirano

We adopt the standard definition of diffeomorphism for Regge gravity in D=2 and give an exact expression of the Liouville action in the discretized case. We also give the exact form of the integration measure for the conformal factor. In D>2 we extend the approach to any family of geometries described by a finite number of parameters. The ensuing measure is

Nicoletta Stella

We present the preliminary results of the first Lattice study of the baryonic Isgur and Wise function obtained from the matrix element of the weak current between $Λ$-baryon external states. Its dependence on the heavy and light quark masses is studied. Some result on the semi-leptonic decay $Λ_b\toΛ_c +lν$ are given.

Vicente Azcoiti

We show how the prescription of taking the absolute value of the fermion determinant in the integration measure of QCD at finite density, forgetting its phase, reproduces the correct thermodynamical limit. This prescription, which applies also to other gauge theories with non-positive-definite integration measure, also has the advantage of killing finite siz

Vicente Azcoiti

A short review of some of the most relevant contributions to non-perturbative QED is done. Since a Gaussian behaviour of QED à la $λϕ^4$ has been ruled out by the numerical data, I analyse the other two most reliable scenarios, i.e. triviality à la Nambu-Jona Lasinio and non-Gaussian critical behaviour. I give a suggestive theoretical argument against a Gaus

John D. Barrow, Paul Parsons

We provide a detailed analysis of Friedmann-Robertson-Walker universes in a wide range of scalar-tensor theories of gravity. We apply solution-generating methods to three parametrised classes of scalar-tensor theory which lead naturally to general relativity in the weak-field limit. We restrict the parameters which specify these theories by the requirements

B. L. Hu

In the spirit of Sakharov&#39;s `metric elasticity&#39; proposal, we draw a loose analogy between general relativity and the hydrodynamic state of a quantum gas. In the `top-down&#39; approach, we examine the various conditions which underlie the transition from some candidate theory of quantum gravity to general relativity. Our emphasis here is more on the

Ola Bratteli, Akitaka Kishimoto, Derek W. Robinson

We show that invariant states of C*-dynamical systems can be approximated in the weak*-topology by invariant pure states, or almost invariant pure states, under various circumstances.

Yigal Meir, Boris L. Altshuler

It is shown that in the presence of strong magnetic fields, spin-orbit scattering causes a sharp increase in the effective density of states in the variable-range hopping regime when temperature decreases. This effect leads to an exponential enhancement of the conductance above its value without spin-orbit scattering. Thus an experimental study of the hoppin

S. A. Cannas, F. A. Tamarit

The Ising model with ferromagnetic interactions that decay as $1/r^α$ is analyzed in the non-extensive regime $0\leqα\leq d$, where the thermodynamic limit is not defined. In order to study the asymptotic properties of the model in the $N\rightarrow\infty$ limit ($N$ being the number of spins) we propose a generalization of the Curie-Weiss model, for which t

Aris L. Moustakas, Daniel S. Fisher

Tunnelling impurities in metals have been known for some time to have the potential for exhibiting Kondo-like physics. However previous models based on an impurity hopping between two equivalent positions have run into trouble due to the existence of relevant operators that drive the system away from the non-Fermi-liquid Kondo fixed point. In the case of an

Lei Zhou, Ruibao Tao

In this paper, the conventional Holstein-Primakoff method is generalized with the help of the characteristic angle transformation [Lei Zhou and Ruibao Tao, J. Phys. A {\bf 27} 5599 (1994)] for the spin-one magnetic systems with single-ion anisotropies. We find that the weakness of the conventional method for such systems can be overcome by the new approach.

J. Boronat, J. Casulleras

Diffusion Monte Carlo results for the phonon-roton excitation branch in bulk liquid $^4$He at zero temperature are presented. The sign problem associated to the excited wave function has been dealt both with the fixed-node approximation and the released-node technique. The upper bounds provided by the fixed-node approximation are shown to become exact when u

Ben Yu-Kuang Hu

We study the transresistivity $\tensorρ_{21}$ (or equivalently, the drag rate) of two Coulomb-coupled quantum wells in the presence of a perpendicular magnetic field, using semi-classical transport theory. Elementary arguments seem to preclude any possibility of observation of ``Hall drag&#39;&#39; (i.e., a non-zero off-diagonal component in $\tensorρ_{21}$)

Min-Fong Yang

Within the intermediate-coupling theory, the quasiparticle weight $Z$ of one hole injected in the undoped antiferromagnetic ground state is studied. We find that, for the hole located at the quasiparticle band minimun with momentum ${\bf k}_0 = (\pm \fracπ{2}, \pm \fracπ{2})$, $Z$ is finite. By comparing the results obtained by the self-consistent Born appro

C. Dasgupta, J. M. Kim, M. Dutta, S. Das Sarma

We show by numerical simulations that discretized versions of commonly studied continuum nonlinear growth equations (such as the Kardar-Parisi-Zhang equation and the Lai-Das Sarma equation) and related atomistic models of epitaxial growth have a generic instability in which isolated pillars (or grooves) on an otherwise flat interface grow in time when their

L. Longa, E. M. F. Curado, F. A. Oliveira

Numerical experiments recently discussed in the literature show that identical nonlinear chaotic systems linked by a common noise term (or signal) may synchronize after a finite time. We study the process of synchronization as function of precision of calculations. Two generic behaviors of the average coalescence time are identified: exponential or linear. I

J. Duan, J. Nee

In this letter, a coupled system of viscous Burgers&#39; equations with zero Dirichlet boundary conditions and appropriate initial data is considered. For the well-known single viscous Burgers&#39; equation with zero Dirichlet boundary conditions, the zero equilibrium is the unique global exponential point attractor. A similar property is shown for the coupl

D. Yu. Wolchenkov

A method of construction of decomposition of correlation functions of developed turbulence in a compressible fluid on Mach number {\em Ma} is generalized now for a model of stochastic magnetic hydrodynamics. With the help of the field theory renormalization group method the composite operators of transversal fields are studied. It is shown, that in the case

Norbert Schartel, Paul J. Green, Scott F. Anderson, Paul C. Hewett

We develop and apply a novel method of analysis to study the X-ray spectral properties of 908 QSOs in the Large Bright Quasar Survey (LBQS) that were observed during the soft X-ray ROSAT All-Sky Survey (RASS). Due to the relatively short (<600sec) RASS exposure times, only 10% of the QSOs are detected in X-rays, so X-ray spectral model fits for individual QS

G. Kriss, J. Krolik, J. Grimes, Z. Tsvetanov

We observed a total of 13 low-redshift AGN with the Hopkins Ultraviolet Telescope (HUT) during the course of the Astro-1 and Astro-2 missions. Of these, 4 show intrinsic Lyman limit absorption---NGC 1068, NGC 4151, NGC 3516 and NGC 3227. All galaxies with optically thick Lyman limits have extended narrow-line regions with bi-polar morphologies. All AGN with

Patrick Palmer, W. Miller Goss

Since its identification as the Galactic Center, the radio source Sagittarius A has been a target of intense research. Due to the high density of sources in the Galactic Center and differing observing techniques, the nomenclature of sources in this region has changed over the years, with sources having several names, as well as the same names being used for

Sabine Moehler, Uli Heber, Gero Rupprecht

We present spectroscopic analyses of 17 faint blue stars in the globular cluster NGC 6752. Effective temperatures, surface gravities, and helium abundances are determined and compared to theoretical predictions. All stars are helium deficient by factors of 3 to more than 100, indicative of gravitational settling of helium. Stars with Teff > 20000 K (sdBs) fi

J. I. Collar

It is shown that under realistic background considerations, an improvement in Cold Dark Matter sensitivity of several orders of magnitude is expected from a detector based on superheated liquid droplets. Such devices are totally insensitive to minimum ionizing radiation while responsive to nuclear recoils of energies ~ few keV. They operate on the same princ

A. Lavagno, G. Kaniadakis, M. Rego-Monteiro, P. Quarati

We show that the observational data recently provided by Giovanelli et al. (1996 a, b) and discussed by Bahcall and Oh (1996) concerning the velocity distribution of clusters of galaxies can be naturally fitted by a statistical distribution which generalizes the Maxwell-Boltzmann one (herein recovered for the entropic index $q=1$). Indeed a recent generaliza

J. Ge, B. Jacobsen, J. R. P. Angel, N. Woolf

A prototype ultrahigh resolution spectrograph has been built with an adaptive optics telescope. It provides $250,000$ resolving power, 300 Å wavelength coverage and 0.8\% efficiency.

K. N. Ilinski, A. S. Stepanenko

In the paper we consider a hydrodynamical description of a nonideal Bose gas in one-loop approximation. We calculate an effective action which consists of mean field contributions and first quantum correction. This provides the equations of motion for the density and velocity of the gas where both mean field contributions and fluctuations are presented. To f

Randall J. Splinter, Adrian L. Melott, Angela Linn, Charles Buck

In this study we use simulations of 128$^3$ particles to study the ellipticity and orientation of clusters of galaxies in N-body simulations of differing power-law initial spectra (P(k) \propto k^n ,n = +1, 0, -1, -2$), and density parameters ($Ω_0 = 0.2$ to 1.0). Furthermore, unlike most theoretical studies we mimic most observers by removing all particles

Adrian Ghinculov

The selfcoupling of the Higgs field grows with the mass of the Higgs particle and induces potentially large radiative corrections in the electroweak model. The technical aspects of performing multiloop calculations in the massive case are discussed briefly. I review the status of two-loop calculations of radiative corrections of enhanced electroweak strength

H. J. Mo, Y. P. Jing, G. Börner

We show that in a hierarchical clustering model the low-order statistics of the density and the peculiar velocity fields can all be modelled semianalytically for a given cosmology and an initial density perturbation power spectrum $P(k)$. We present such models for the two-point correlation function $ξ(r)$, the amplitude $Q$ of the three-point correlation fu

Maxim Braverman

Let $M$ be a complete Riemannian manifold and let $Ω^*(M)$ denote the space of differential forms on $M$. Let $d:Ω^*(M) \to Ω^{*+1}(M)$ be the exterior differential operator and let $\Del=dd^*+d^*d$ be the Laplacian. We establish a sufficient condition for the Schroedinger operator $H=\Del+V(x)$ (where the potential $V(x):Ω^*(M)\to Ω^*(M)$ is a zero order di

M. Chaichian, W. F. Chen

We perform two-loop calculation of Chern-Simons in background field method using the hybrid regularization of higher-covariant derivative and dimensional regularization. It is explicitly shown that Chern-Simons field theory is finite at the two-loop level. This finiteness plays an important role in the relation of Chern-Simons theory with two-dimensional con

N. V. Borisov, Kirill Ilinski, Gleb Kalinin

Laplace operators perturbed by meromorphic potential on the Riemann and separated type Klein surfaces are constructed and their indices are calculated by two different ways. The topological expressions for the indices are obtained from the study of spectral properties of the operators. Analytical expressions are provided by the Heat Kernel approach in terms

K. Intriligator, N. Seiberg

We discuss non-trivial fixed points of the renormalization group with dual descriptions in $N=4$ gauge theories in three dimensions. This new duality acts as mirror symmetry, exchanging the Higgs and Coulomb branches of the theories. Quantum effects on the Coulomb branch arise classically on the Higgs branch of the dual theory. We present examples of dual th

Thorsten Ohl

I describe parameterizations of realistic $e^\pm$- and $γ$-beam spectra at future linear $e^+e^-$-colliders. Emphasis is put on simplicity and reproducibility of the parameterizations, supporting reproducible physics simulations. The parameterizations are implemented in a library of distribution functions and event generators.

Jonathan L. Feng

If sleptons are produced at LEP II or the Next Linear Collider, lepton flavor violation can be probed at a level significantly below the current bounds from rare processes, such as $μ\to eγ$. Polarizable $e^-$ beams and the $e^-e^-$ mode at the NLC are found to be powerful options.

Hilmar Forkel

We analyze the nucleon matrix element of the strange quark vector current in a nucleon--model independent dispersive approach with input from the current world data set for the isoscalar electromagnetic form factors. The update of Jaffe&#39;s minimal 3-pole ansatz for the spectral functions yields a 40% larger (Sachs) strangeness radius, $(r_s^2)_{Sachs} = 0

V. K. Mitrjushkin

The solutions of the classical equations of motion on a periodic lattice are found which correspond to abelian single and double Dirac sheets. These solutions exist also in non--abelian theories. Possible applications of these solutions to the calculation of gauge dependent and gauge invariant observables are discussed.

R. B. Mann

The pair creation of black holes with event horizons of non-trivial topology is described. The spacetimes are all limiting cases of the cosmological $C$ metric. They are generalizations of the $(2+1)$ dimensional black hole and have asymptotically anti de Sitter behaviour. Domain walls instantons can mediate their pair creation for a wide range of mass and c

C. J. Isham

A major problem in the consistent-histories approach to quantum theory is contending with the potentially large number of consistent sets of history propositions. One possibility is to find a scheme in which a unique set is selected in some way. However, in this paper we consider the alternative approach in which all consistent sets are kept, leading to a ty

Giancarlo Jug, Boris N. Shalaev

The critical behavior of two-dimensional (2D) anisotropic systems with weak quenched disorder described by the so-called generalized Ashkin-Teller model (GATM) is studied. In the critical region this model is shown to be described by a multifermion field theory similar to the Gross-Neveu model with a few independent quartic coupling constants. Renormalizatio

C. H. Booth, F. Bridges, G. J. Snyder, T. Geballe

X-ray-absorption fine-structure measurements at the Mn $K$-edge as a function of temperature were performed on samples of La$_{1-x}$Ca$_x$MnO$_3$ and La$_{0.67}$Pb$_{0.33}$MnO$_3$. All samples have a metal-insulator (MI) transition near the ferromagnetic transition, except the Ca$_{0.5}$ sample, which does not have a MI transition. Near $T_c$ for the MI samp

Jian Ge, Jill Bechtold, John H. Black

We present detections of absorption from the ground state and excited states of C I in the z = 1.9731 damped Ly\al\ system of the QSO 0013$-$004. The excitation temperature between the J = 0 and J = 1 fine-structure levels of C I is 11.6 $\pm$ 1.0 K. We estimate other contributions to the excitation of the C I fine-structure levels, and use the population ra

Moshe Carmeli

We describe the motion of a particle in a central field in an expanding universe. Use is made of a double expansion in 1/c and 1/T, where c and T are the speed of light and the Hubble time. In the lowest approximation the fourth power of the rotational velocity is shown to be proportional to (2/3)GMcHo, where G is Newton&#39;s gravitational constant, M is th

Russell M. Kulsrud, Renyue Cen, Jeremiah P. Ostriker, Dongsu Ryu

It is demonstrated that strong magnetic fields are produced from a zero initial magnetic field during the pregalactic era, when galaxies are first forming. Their development proceeds in three phases. In the first phase, weak magnetic fields are created by the Biermann battery mechanism, acting in shocked parts of the intergalactic medium where caustics form

Gary C. Hill

New information on the structure of the nucleon from the HERA ep collider leads to higher neutrino cross sections for the processes nu_mu + N --> mu + X needed to calculate the expected rates of astrophysical neutrino induced muons in large detectors either under construction, or in the design stage. These higher cross sections lead to higher muon rates for

Apostolos Pilaftsis

It is shown that Cornwall&#39;s pinch technique can be extended in a consistent diagrammatic way, so as to describe general background field gauges in Yang-Mills theories. The resulting one-loop Green&#39;s functions are found to obey Ward identities identical to those derived from the classical action at the tree level. This generalization of the pinch tech

Tony Gherghetta

If the gravitino is sufficiently light and stable it will behave as an effective massless neutrino species at the time of nucleosynthesis. Depending on the temperature at which it decouples from the thermal bath in the early universe, the gravitino mass will be bounded by the primordial $^4$He abundance. Assuming a conservative estimate that the number of ne

T. Dudok de Wit, V. V. Krasnosel'skikh

Magnetic field fluctuations in the vicinity of the Earth's bow shock have been investigated with the aim to characterize the intermittent behaviour of strong plasma turbulence. The observed small-scale intermittency may be the signature of a multifractal process but a deeper inspection reveals caveats in such an interpretation. Several effects, including the