February 1998 arXiv papers — page 14

Shuichi Murakami

New integrable variant of the one-dimensional Hubbard model with variable-range correlated hopping is studied. The Hamiltonian is constructed by applying the quantum inverse scattering method on the infinite interval at zero density to the one-parameter deformation of the L-matrix of the Hubbard model. By construction, this model has Y(su(2))$\oplus$Y(su(2))

Luca Peliti, Mauro Sellitto

We consider a simple model of a structural glass, represented by a lattice gas with kinetic constraints in contact with a particle reservoir. Quench below the glass transition is represented by the jump of the chemical potential above a threshold. After a quench, the density approaches the critical density-where the diffusion coefficient of the particles van

Pierre Collet, Jean-Pierre Eckmann

We study the set of solutions of the complex Ginzburg-Landau equation in $\real^d, d<3$. We consider the global attracting set (i.e., the forward map of the set of bounded initial data), and restrict it to a cube $Q_L$ of side $L$. We cover this set by a (minimal) number $N_{Q_L}(ε)$ of balls of radius $ε$ in $\Linfty(Q_L)$. We show that the Kolmogorov $ε$-e

J. H. Krolik, G. M. Voit

Spectropolarimetry of Broad Absorption Line Quasars (BALQSO&#39;s) has demonstrated that the geometry of the absorbing material is far from spherically symmetric. Calculations of accretion disk spectra suggest that the intrinsic radiation pattern of quasars is also anisotropic. Because the quasar counts distribution is very steep, if the orientations of thes

A. Kritsuk, H. Boehringer, E. Mueller

Using numerical techniques we studied the global stability of cooling flows in giant elliptical galaxies. As an initial equilibrium state we choose the hydrostatic gas recycling model (Kritsuk 1996). Non-equilibrium radiative cooling, stellar mass loss, heating by type Ia supernovae, distributed mass deposition, and thermal conductivity are included. Althoug

Jeffrey E. McClintock

Most X-ray novae (aka soft X-ray transients) contain black hole primaries. In particular, the large mass functions measured for six X-ray novae directly clinch the argument (within general relativity) that they contain black holes. These firm dynamical results are discussed, and the urgent need to determine precise masses for black holes is stressed. The dyn

J. G. Bartlett, A. Blanchard, D. Barbosa

The recent discovery of two flux decrements in deep radio maps obtained by the VLA and the Ryle Telescope can have powerful implications for the density parameter of the Universe, $\Omo$. We outline these implications by modeling the decrements as the thermal Sunyaev-Zel&#39;dovich (SZ) effect from two clusters assuming their properties are similar to those

F. Frontera, D. Dal Fiume, G. Malaguti, L. Nicastro

We report on highlight results on celestial sources observed in the high energy band (>20 keV) with BeppoSAX. In particular we review the spectral properties of sources that belong to different classes of objects, i.e. stellar coronae (Algol), supernova remnants (Cas A), low mass X-ray binaries (Cygnus X-2 and the X-ray burster GS1826-238), black hole candid

F. -K. Thielemann, T. Rauscher, C. Freiburghaus, K. Nomoto

This review concentrates on nucleosynthesis processes in general and their applications to massive stars and supernovae. A brief initial introduction is given to the physics in astrophysical plasmas which governs composition changes. We present the basic equations for thermonuclear reaction rates and nuclear reaction networks. The required nuclear physics in

M. Breger, A. Pamyatnykh

Period changes of Delta Scuti stars have been collected or redetermined from the available observations and are compared with values computed from evolutionary models with and without convective core overshooting. For the radial pulsators of Pop. I, the observations indicate (1/P) dP/dt values around 10^-7 year^-1 with equal distribution between period incre

Maurizio Salaris, Achim Weiss

New age determinations of the galactic disk globular clusters 47 Tuc, M71 and NGC6352 have been performed with our up-to-date alpha-enhanced stellar models. We find that all three clusters are about 9.2 Gyr old and therefore coeval with the oldest disk white dwarfs. Several arguments are presented which indicate that the initial helium content of the stars p

Naoki Seto, Jun&#39;ichi Yokoyama

Since the cosmic peculiar velocity field depends on small wave-number modes strongly, we cannot probe its universal properties unless we observe a sufficiently large region. We calculate the expected deviation (sample variance) of the peculiar velocity dispersion from its universal value in the case observed volume is finite. Using linear theory we show that

O. Bergman, A. Fayyazuddin

We argue that certain BPS states in the D3-brane probe realization of N=2 SU(2) Super-Yang-Mills theory correspond to multi-pronged strings connecting the D3-brane to the background 7-branes. This provides a physical realization of the decay of these states on the curve of marginal stability, and explains their absence in the strong coupling regime.

Vipul Periwal, Oyvind Tafjord

String configurations have been identified in compactified Matrix theory at vanishing string coupling. We show how the interactions of these strings are determined by the Yang-Mills gauge field on the worldsheet. At finite string coupling, this suggests the underlying dynamics is not well-approximated as a theory of strings. This may explain why string pertu

Igor F. Lyuksyutov, Thomas Nattermann, Valery Pokrovsky

We consider three mechanisms of hysteresis phenomena in alternating magnetic field: the domain wall motion in a random medium, the nucleation and the retardation of magnetization due to slow (critical) fluctuations. We construct quantitative theory for all these processes. The hysteresis is characterized by two dynamic threshold fields, by coercive field and

Jean-Marc Drezet

Let X be a projective irreducible smooth algebraic variety. A &#34;fine moduli space&#34; of sheaves on X is a family F of coherent sheaves on X parametrized by an integral variety M such that : F is flat on M; for all distinct points x, y of M the sheaves F_x, F_y on X are not isomorphic and F is a complete deformation of F_x; F has an obvious local univers

Oliver Redner, Jon Machta, Lincoln Chayes

A two-replica graphical representation and associated cluster algorithm is described that is applicable to ferromagnetic Ising systems with arbitrary fields. Critical points are associated with the percolation threshold of the graphical representation. Results from numerical simulations of the Ising model in a staggered field are presented. The dynamic expon

V. Akulov, I. Bandos, W. Kummer, V. Zima

Superfield equations of motion for D=10 type IIB Dirichlet super-9-brane are obtained from the generalized action principle. The geometric equations containing fermionic superembedding equations and constraints on the generalized field strength of Abelian gauge field are separated from the proper dynamical equations and are found to contain these dynamical e

Ramin Golestanian, Mehran Kardar

A path integral formulation is developed for the dynamic Casimir effect. It allows us to study arbitrary deformations in space and time of the perfectly reflecting (conducting) boundaries of a cavity. The mechanical response of the intervening vacuum is calculated to linear order in the frequency-wavevector plane, using which a plethora of interesting phenom

A. J. Mountain

The Casimir operators of a Lie algebra are in one-to-one correspondence with the symmetric invariant tensors of the algebra. There is an infinite family of Casimir operators whose members are expressible in terms of a number of primitive Casimirs equal to the rank of the underlying group. A systematic derivation is presented of a complete set of identities e

R. Vilela Mendes

In dynamical systems composed of interacting parts, conditional exponents, conditional exponent entropies and cylindrical entropies are shown to be well defined ergodic invariants which characterize the dynamical selforganization and statitical independence of the constituent parts. An example of interacting Bernoulli units is used to illustrate the nature o

J. -M. Frère, D. Monderen

Motivated by a pilot experiment conducted by F.Vannucci et al. during a solar eclipse, we work out the geometry governing the radiative decays of solar neutrinos. Surprisingly, although a smaller proportion of the photons can be detected, the case of strongly non-degenerate neutrinos brings better limits in terms of the fundamental couplings. We advocate sat

J. S. Dowker

The discrepancy between the anomaly found by Bousso and Hawking (hep-th/9705236) and that of other workers is explained by the omission of a zero mode contribution to the effective action.

Mark Dickinson

The quality, depth, and multi-color nature of the Hubble Deep Field images makes them an excellent resource for studying galaxies at z > 2 using selection techniques based on the presence of the 912A Lyman break. I present a descriptive review of this method and of the properties of the objects which it identifies, and summarize spectroscopic progress on gal

T Prestidge

In a quantum theory of gravity, fluctuations about the vacuum may be considered as Planck scale virtual black holes appearing and annihilating in pairs. Incident fields scattering from such fluctuations would lose quantum coherence. In a recent paper (hep-th/9705147), Hawking and Ross obtained an estimate for the magnitude of this loss in the case of a scala

Olivier Piguet, Sylvain Wolf

The supercurrent components of the N=1, D=4 Super-Yang-Mills theory in the Wess-Zumino gauge are coupled to the components of a background supergravitation field in the ``new minimal'' representation, in order to describe the various conservation laws in a functional way through the Ward identities for the diffeomorphisms and for the local supersymmetry, Lor

S. Hyun

By following Seiberg&#39;s prescriptions on DLCQ of $M$ theory, we give the background geometries of DLCQ supergravity associated with $N$ sector of DLCQ of $M$ theory on $T^p$ with vanishingly small radii. Most of these are the product of anti-de Sitter spacetimes and spheres, which have been found as the spontaneous compactifications of eleven dimensional

Didier Sornette

Risk control and optimal diversification constitute a major focus in the finance and insurance industries as well as, more or less consciously, in our everyday life. We present a discussion of the characterization of risks and of the optimization of portfolios that starts from a simple illustrative model and ends by a general functional integral formulation.

Maxim Markevitch

The X-ray luminosity-temperature relation for nearby T=3.5-10 keV clusters is rederived using new ASCA temperatures and ROSAT luminosities. Both quantities are derived by directly excluding the cooling flow regions. This correction results in a greatly reduced scatter in the Lx-T relation; cooling flow clusters are similar to others outside the small cooling

Carlos Castro

A geometric derivation of $W_\infty$ Gravity based on Fedosov&#39;s deformation quantization of symplectic manifolds is presented. To lowest order in Planck&#39;s constant it agrees with Hull&#39;s geometric formulation of classical nonchiral $W_\infty$ Gravity. The fundamental object is a ${\cal W}$-valued connection one form belonging to the exterior algeb

Daniel J. H. Chung, Edward W. Kolb, Antonio Riotto

We show that in large-field inflationary scenarios, superheavy (many orders of magnitude larger than the weak scale) dark matter will be produced in cosmologically interesting quantities if superheavy stable particles exist in the mass spectrum. We show that these particles may be produced naturally during the transition from the inflationary phase to either

Gennady P. Berman, Gary D. Doolen, Gustavo V. Lopez, Vladimir I. Tsifrinovich

We investigate numerically a single-pulse implementation of a quantum Control-Not (CN) gate for an ensemble of Ising spin systems at room temperature. For an ensemble of four-spin ``molecules&#39;&#39; we simulate the time-evolution of the density matrix, for both digital and superpositional initial conditions. Our numerical calculations confirm the feasibil

Gennady P. Berman, Gary D. Doolen, Gustavo V. Lopez, Vladimir I. Tsifrinovich

When dealing with macroscopic objects one usually observes quasiclassical phenomena, which can be described in terms of quasiclassical (or classical) equations of motion. Recent development of the theory of quantum computation is based on implementation of the entangled states which do not have a classical analogy. Using a simple example of a paramagnetic sp

Cheuk-Yin Wong, Shui-Yin Lo

We examine the physical processes which are involved in the formation and stability of the anomalous states of water reported recently. The initial step of adding a small amount of ionic compound XY to pure water leads to the formation of water clusters (X^+)(H2O)_n and (Y^-)(H2O)_n with n>>1. The structure of the cluster around the ion depends strongly on t

A. Tavakoli, D. D. Tskhakaya

New types of symmetry for the Rayleigh equation are found. For small Atwood number, an analytic solution is obtained for a smoothly varying density profile. It is shown that a transition layer with a finite width can undergo some kind of stratification.

B. Blankleider, A. N. Kvinikhidze

We present a unified description of the relativistic piNN and gamma-piNN systems where the strong interactions are described non-perturbatively by four-dimensional integral equations. Our formulation obeys two and three-body unitarity and is strictly gauge invariant with photons coupled to all possible places in the strong interaction model. At the same time

Yasushi Nara

A parton-hadron cascade model which is the extension of hadronic cascade model incorporating hard partonic scattering based on HIJING is presented to describe the space-time evolution of parton/hadron system produced by ultra-relativistic nuclear collisions. Hadron yield, baryon stopping and transverse momentum distribution are calculated and compared with H

Denka Kutzarova

We prove that Schlumprecht space $S$ is isomorphic to $(\sum_{k=1}^\infty \oplus \ell_infty ^{n_k})_S $ for any sequence of integers $(n_k)$. We also show that every complemented subspace of $S$ which has some subsymmetric basis, is isomorphic to $S$.

Weiping Li

We develop a method of calculation for the symplectic Floer homology of composite knots. The symplectic Floer homology of knots defined in \cite{li} naturally admits an integer graded lifting, and it formulates a filtration and induced spectral sequence. Such a spectral sequence converges to the symplectic homology of knots in \cite{li}. We show that there i

John C. Baez, James Dolan

Categorification is the process of finding category-theoretic analogs of set-theoretic concepts by replacing sets with categories, functions with functors, and equations between functions by natural isomorphisms between functors, which in turn should satisfy certain equations of their own, called `coherence laws&#39;. Iterating this process requires a theory

R. A. Sharipov

For the equations of the form $y&#39;&#39;=P(x,y)+3 Q(x,y) y&#39;+3 R(x,y) {y&#39;}^2 +S(x,y) {y&#39;}^3$ the problem of equivalence in the class of point transformations is considered. Effective procedure for determining the class of point equivalence for the given equation is suggested. This procedure is based on explicit formulas for the invariants.

Hunter S. Snevily, Douglas B. West

We introduce a combinatorial enumeration problem that is solved using generalized Catalan numbers. We also study generalizations of the Cycle Lemma beyond the computation of the generalized Catalan numbers.

Le Tu Quoc Hung, Maciej M. Syslo, Margaret L. Weaver, Douglas B. West

The bandwidth of a graph G is the minimum of the maximum difference between adjacent labels when the vertices have distinct integer labels. We provide a polynomial algorithm to produce an optimal bandwidth labeling for graphs in a special class of block graphs (graphs in which every block is a clique), namely those where deleting the vertices of degree one p

Rainer H. Kaenders

For plane curve singularities we construct a mixed Hodge structure (MHS) over the integers on the fundamental group of the Milnor fiber. The concept nearby fundamental group is introduced and we develop a theory of iterated integrals along elements of this group. We give an example for which the MHS on the nearby fundamental group detects a modulus which is

C. R. Stephens, A. Weber, J. C. Lopez Vieyra, P. O. Hess

The asymptotic high momentum behaviour of quantum field theories with cubic interactions is investigated using renormalization group techniques in the asymmetric limit x << 1. Particular emphasis is paid to theories with interactions involving more than one field where it is found that a matrix renormalization is necessary. Asymptotic scaling forms, in agree

S. W. Hawking, Neil Turok

We show that within the framework of a definite proposal for the initial conditions for the universe, the Hartle-Hawking `no boundary&#39; proposal, open inflation is generic and does not require any special properties of the inflaton potential. In the simplest inflationary models, the semiclassical approximation to the Euclidean path integral and a minimal

Kazuo Fujikawa

We suggest to take the fluctuation-dissipation theorem of Callen and Welton as a basis to study quantum dissipative phenomena (such as macroscopic quantum tunneling) in a manner analogous to the Nambu-Goldstone theorem for spontaneous symmetry breakdown. It is shown that the essential physical contents of the Caldeira-Leggett model such as the suppression of

Phillial Oh

We propose an integrable extension of nonlinear sigma model on the target space of Hermitian symmetric space (HSS). Starting from a discussion of soliton solutions of O(3) model and an integrally extended version of it, we construct general theory defined on arbitrary HSS by using the coadjoint orbit method. It is based on the exploitation of a covariantized

J. F. Gunion

I discuss the exciting prospects for exploring a wide range of new physics at a low-energy muon collider.

A. Pich

Precision measurements of electroweak observables provide stringent tests of the Standard Model structure and an accurate determination of its parameters. A brief overview of the present experimental status is presented. A more extensive discussion can be found in Ref. hep-ph/9711279

James Steele, Hidenaga Yamagishi, Ismail Zahed

The electromagnetic emission rates at SPS energies satisfy spectral constraints in leading order in the pion and nucleon densities. These constraints follow from the strictures of broken chiral symmetry. We saturate these constraints using available data, leading to model independent emission rates from a hadronic gas. With a simple fire-ball scenario, only

M. C. Gonzalez-Garcia, A. Gusso, S. F. Novaes

We establish constraints on a general four-fermion contact interaction from precise measurements of electroweak parameters. We compute the one-loop contribution for the leptonic $Z$ width, anomalous magnetic, weak-magnetic, electric and weak dipole moments of leptons in order to extract bounds on the energy scale of these effective interactions.

J. D. Vergados

The modulation effect in the direct detection of supersymmetric Cold Dark Matter (CDM) particles is investigated. It is shown that, while normally the modulation effect in the total event rate is small, $\leq 5% $, in some special cases it becomes much larger. It also becomes more pronounced in the differential event rate. It may thus be exploited to discrim

J. F. Gunion, C. -H. Chen

We quantitatively explore, in the context of the D0 detector at the Tevatron, three very different techniques for observing delayed decays of the lightest neutralino of a simple gauge-mediated supersymmetry breaking (GMSB) model to photon plus gravitino. It is demonstrated that the delayed-decay signals considered can greatly increase the region of general G

S. Bar-Shalom, G. Eilam, A. Soni

We consider the sneutrino resonance reaction l^+ l^- -> sneutrino -> tau^+ tau^- in the MSSM without R-parity. We introduce new CP-violating and CP-conserving tau-spin asymmetries which are generated already at the tree-level if there is sneutrino - sneutrino-bar mixing and that are forbidden in the SM. It is remarkable that these spin asymmetries can reach

K. Martins, D. Blaschke

We investigate $J/ψ$ suppression in ultrarelativistic heavy ion collisions within a generalized GLAUBER model and compare results of a hadronic comover scenario with those of a quark plasma scenario where conditions for MOTT dissociation of charmonium are fulfilled locally at the short time scales before hadronization. We study possible consequences for the

L. Del Debbio, M. Faber, J. Greensite, S. Olejnik

We present numerical evidence that supports the theory of quark confinement based on center vortex condensation. We introduce a special gauge (&#34;maximal center gauge&#34;) and center projection, suitable for identification of center vortices. Main focus is then put on the connection of vortices in center projection to &#34;confiners&#34; in full, unprojec

Sergio Caracciolo, Fabrizio Palumbo

A quadratic action in even Grassmann variables with the quantum numbers of the pions has been studied. It includes the $σ$-field in order to be invariant under SU(2)_L times SU(2)_R transformations over the quarks. This action exhibits the Goldstone phenomenon reducing its symmetry to the O(3) isospin invariance. The model has been investigated in the Strato

The OPAL Collaboration, K. Ackerstaff et al

In e^+e^- collisions at centre-of-mass energies around 91 GeV, D^*0 mesons have been reconstructed using data collected with the OPAL detector at LEP. The hadronisation fraction has been measured to be f(c -> D^*0) = 0.218 +/- 0.054 +/- 0.045 +/- 0.007, where the errors correspond to the statistical and systematic errors specific to this analysis, and to sys

Andrei Mudrov, Konstantin Varnashev

The structure of the renormalization-group flows in a model with three quartic coupling constants is studied within the $ε$-expansion method up to three-loop order. Twofold degeneracy of the eigenvalue exponents for the three-dimensionally stable fixed point is observed and the possibility for powers in $\sqrtε$ to appear in the series is investigated. Relia

P. Butaud, R. Mélin

We analyze the violations of linear fluctuation-dissipation theorem (FDT) in the coarsening dynamics of the antiferromagnetic Ising model on percolation clusters in two dimensions. The equilibrium magnetic response is shown to be non linear for magnetic fields of the order of the inverse square root of the number of sites. Two extreme regimes can be identifi

B. I. Halperin, Ady Stern

Despite the fact that composite fermions may be regarded as electrically neutral objects at Landua-level filling factor $ν=1/2$, carrying only an electric dipole moment, we argue that the long-wavelength compressibility of the system is finite.

P. Garbaczewski, G. Kondrat

We explore a connection of the forced Burgers equation with the Schrödinger (diffusive) interpolating dynamics in the presence of deterministic external forces. This entails an exploration of the consistency conditions that allow to interpret dispersion of passive contaminants in the Burgers flow as a Markovian diffusion process. In general, the usage of a c

Scott M. Zoldi

Using the Lorenz equations, we have investigated whether unstable periodic orbits (UPOs) associated with a strange attractor may predict the occurrence of the robust sharp peaks in histograms of some experimental chaotic time series. Histograms with sharp peaks occur for the Lorenz parameter value r=60.0 but not for r=28.0, and the sharp peaks for r=60.0 do

P. W. Morris, T. Shanks

We have used archive HST WFPC2 data for three elliptical galaxies (NGC 3379 in the Leo I group, and NGC 4472 and NGC 4406 in the Virgo cluster) to determine their distances using the Surface Brightness Fluctuation (SBF) method as described by Tonry and Schneider (1988). A comparison of the HST results with the SBF distance moduli of Ciardullo et al (1993) sh

F. D&#39;Acri, S. De Grandi, S. Molendi

Ground and in flight calibrations of the MECS experiment on board Beppo-SAX have demonstrated that this is currently the best X-ray imaging experiment above 3 keV. The MECS on-axis PSF has a half power radius of about 1 arcmin. Moreover due to a fortunate combination of detector and mirror PSFs the total PSF depends only weakly on the energy. Finally the deg

S. Molendi

The high spatial resolution of the MECS experiment on board Beppo-SAX has encouraged a few scientists, including the author, to perform observations of galaxy clusters. Results from the analysis of the first few observed objects are encouraging. After having reviewed the Beppo-SAX observing program for galaxy clusters and referenced contributions to these pr

A. C. Goncalves, P. Veron, M. -P. Veron-Cetty

Ground based long slit spectroscopic observations of the nuclear region of NGC 5252, and Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) spectra of the nucleus and two bright knots located 0.36&#34; NE and 0.31&#34; SW from it, show that the nuclear region exhibits the characteristics of a Liner with exceptionally strong [OI] emission, all lines

S. Molendi, G. Matt, L. A. Antonelli, F. Fiore

The analysis of Perseus data collected with the Medium Energy Concentrator Spectrometer (MECS) on board Beppo-SAX shows that the ratio of the flux of the 8 keV line complex (dominated by Fe K$_β$ emission) over the 6.8 keV line complex (dominated by Fe K$_α$ emission) is significantly larger than predicted by standard thermal emission codes. Moreover the ana

C. L. Carilli, D. E. Harris, L. Pentericci, H. J. A. Rottgering

A third possible explanation for the X-ray emission from the z=2.156 radio galaxy 1138-262 is thermal emission from a very dense, sub-cluster `halo&#39;, perhaps associated with the (forming) cD galaxy on a scale < 100 kpc. For instance, increasing the gas density from 0.01 cm^{-3} to 0.1 cm^{-3} would decrease the required hot gas mass by the same factor, a

J. M. Kommers, D. Chakrabarty, W. H. G. Lewin

The low-mass X-ray binary pulsar 4U 1626-67 shows 0.048 Hz quasi-periodic oscillations (QPOs) and red noise variability as well as coherent pulsations at the 0.130 Hz neutron star spin frequency. Power density spectra of observations made with the Rossi X-ray Timing Explorer show significant sidebands separated from the pulsar spin frequency (and its harmoni

Y. Mellier

Gravitational lensing can be used to analyze the redshift distribution of faint galaxies. In particular the magnification bias modifies locally the galaxy number density of lensed sources observed in lensing clusters. This depletion area probes the redshift distribution of galaxies beyond B=25. In this proceeding I present this new tool to infer the redhsift

Henning Heiselberg

The kaon energy in a nuclear medium and its dependence on kaon-nucleon and nucleon-nucleon correlations is discussed. The transition from the Lenz potential at low densities to the Hartree potential at high densities can be calculated analytically by making a Wigner-Seitz cell approximation and employing a square well potential. As the Hartree potential is l

Dario Grasso

After a brief presentation of the general techniques used to determine neutrino potentials in a magnetized medium I will discuss MSW resonant oscillations of active and sterile neutrinos in such environment. Using my results I will reconsider the viability of a solution of the pulsar velocity puzzle based on such a kind of neutrino oscillations.

M. S. Brotherton, Beverley J. Wills, Arjun Dey, Wil van Breugel

We present Keck spectropolarimetry of the highly polarized radio-loud quasar 3CR 68.1 (z=1.228, V=19). The polarization increases from 5 in the red (4000 A rest-frame) to >10% in the blue (1900 A rest-frame). The broad emission lines are polarized the same as the continuum, which shows that 3CR 68.1 is not a blazar as it has sometimes been regarded in the pa

Q. Luo, R. J. Protheroe

It is shown that for moderately hot polar caps (with effective temperature of $\sim 10^6$ K), the efficiency of polar gap acceleration is lower compared to the case in which the polar caps are relatively cool and inverse Compton scattering plays no role in controlling the gap. For young pulsars with superstrong magnetic fields ($\geq10^9 T$) and hot polar ca

David A. Brown, Pawel Danielewicz

Within QED, we examine several issues related to constructing a parton-model-based QCD transport theory. We rewrite the QED analog of the parton model, the Weizsaecker-Williams Approximation, entirely in terms of phase-space quantities and we study the phase-space photon and electron densities created by a classical point charge. We find that the densities t

A. Connors, G. J. Hueter

The serendipitous observation of GRB 780506 by co-aligned gamma-ray (HEAO 1 A-4 0.02 - 6 MeV) and X-ray (HEAO 1 A-2 2-60 keV) instruments during a six hour pointing at a blank section of the sky gave us unprecedented high signal-to-noise X-ray spectra and light curves of a gamma-ray burst and its afterglow. We observed two breaks in the initial spectrum, one

Jan de Boer, M. B. Halpern

Recently, we have studied the general Virasoro construction at one loop in the background of the general non-linear sigma model. Here, we find the action formulation of these new conformal field theories when the background sigma model is itself conformal. In this case, the new conformal field theories are described by a large class of new spin-two gauged si

Doug Bullock, Charles Frohman, Joanna Kania-Bartoszynska

See q-alg/9710003 for the corrected version of this paper.

Hok-Ling Lee, John P. Carini, David V. Baxter, George Gruner

Millimeter-wave transmission measurements have been performed in amorphous niobium-silicon alloy samples where the DC conductivity follows the critical temperature dependence $σ_{dc} \propto T^{1/2}$. The real part of the conductivity is obtained at eight frequencies in the range 87--1040 GHz for temperatures 2.6 K and above. In the quantum regime ($\hbar ω>

G. Cvetic, R. Koegerler

Applicability of the previously introduced method of modified diagonal Baker-Gammel approximants is extended to truncated perturbative series (TPS) of any order in gauge theories. The approximants reproduce the TPS when expanded in power series of the gauge coupling parameter to the order of that TPS. The approximants have the favorable property of being exa

Ian Affleck

The exact amplitude for the asymptotic correlation function in the S=1/2 Heisenberg antiferromagnetic chain is determined: <S^a_0 S^b_r> goes to (-1)^r delta^{ab}(ln r)^{1/2}/[(2 pi)^{3/2}r]. The behaviour of the correlation functions for small xxz anisotropy and the form of finite-size corrections to the correlation function are also analysed.

Nathan M. Dunfield

This paper proves a theorem about Dehn surgery using a new theorem about PSL(2, C) character varieties. Confirming a conjecture of Boyer and Zhang, this paper shows that a small hyperbolic knot in a homotopy sphere having a non-trivial cyclic slope r has an incompressible surface with non-integer boundary slope strictly between r-1 and r+1. A corollary is th

Alberto Alvarez, Emilio Hernandez-Garcia, Joaquin Tintore

We study the appearance of large scale mean motion sustained by stochastic forcing on a rotating fluid (in the quasigeostrophic approximation) flowing over topography. As in other noise rectification phenomena, the effect requires nonlinearity and absence of detailed balance to occur. By application of an analytical coarse graining procedure we identify the

D. Augier, D. Poilblanc, E. Sorensen, I. Affleck

The role of dynamical magneto-elastic coupling in spin-Peierls chains is investigated by numerical and analytical techniques. We show that a Heisenberg spin chain coupled to dynamical optical phonons exhibits a transition towards a spontaneously dimerized state in a wide range of parameter space. The low energy excitations are characterized as solitons. No b

C. Gerschel, J. Hufner

Data and their interpretations are reviewed for $J/ψ$ and $ψ^{\prime}$ production in heavy ion collisions with particular emphasis on the recently reported discontinuity in $Pb$-$Pb$ reactions. The experimental set-up is described and the various results for $J/ψ$ and $ψ^{\prime}$ suppressions including their $p_T$-dependence are presented. The suppressions

Eugene V. Sukhorukov, Daniel Loss

We prove the universality of shot-noise in multiterminal diffusive conductors of arbitrary shape and dimension for purely elastic scattering as well as for hot electrons. Using a Boltzmann-Langevin approach we reduce the calculation of shot-noise correlators to the solution of a diffusion equation. We show that shot-noise in multiterminal conductors is a non

Avinash Singh

A numerical method is described for evaluating transverse spin correlations in the random phase approximation. Quantum, spin-fluctuation corrections to sublattice magnetization are evaluated for the half-filled Hubbard antiferromagnet in two and three dimensions in the whole U/t range. Extension to the case of defects in the Hubbard AF is discussed, and the

G. Lazarides, N. Tetradis

We investigate the viability of a two-stage inflationary scenario in the context of supergravity, so as to resolve the problem of initial conditions for hybrid inflation. We allow for non-renormalizable terms in the superpotential and consider the most general form of the Kahler potential and the gauge kinetic function. We construct a model with two stages o

Michal Chodorowski, Ewa Lokas, Agnieszka Pollo, Adi Nusser

Using third-order perturbation theory, we derive a relation between the mean divergence of the peculiar velocity given density and the density itself. Our calculations assume Gaussian initial conditions and are valid for Gaussian filtering of the evolved density and velocity fields. The mean velocity divergence turns out to be a third-order polynomial in the

J. H. Kühn, M. Steinhauser

An evaluation of the effective QED coupling at the scale M_Z is presented. It employs the predictions of perturbative QCD for the cross section of electron positron annihilation into hadrons up to order α_s^2, including the full quark mass dependence, and of order α_s^3 in the high energy region. This allows to predict the input for the dispersion relations

S. E. Massen, C. P. Panos

The position- and momentum-space information entropies of the electron distributions of atomic clusters are calculated using a Woods-Saxon single particle potential. The same entropies are also calculated for nuclear distributions according to the Skyrme parametrization of the nuclear mean field. It turns out that a similar functional form S=a+b ln N for the

S. Mayburov

Aharonov-Kaufherr model of quantum space-time which accounts Reference Frames (RF) quantum effects is considered in Relativistic Quantum Mechanics framework. For RF connected with some macroscopic object its free quantum motion - wave packet smearing results in additional uncertainty of test particle coordinate. Due to the same effects the use of Galilean or

J. Guerrero, V. Aldaya

A quantum realization of the Relativistic Harmonic Oscillator is realized in terms of the spatial variable $x$ and ${\d\over \d x}$ (the minimal canonical representation). The eigenstates of the Hamiltonian operator are found (at lower order) by using a perturbation expansion in the constant $c^{-1}$. Unlike the Foldy-Wouthuysen transformed version of the re

U. Elsner, V. Mehrmann, F. Milde, R. A. Roemer

We present a comparative study of the application of modern eigenvalue algorithms to an eigenvalue problem arising in quantum physics, namely, the computation of a few interior eigenvalues and their associated eigenvectors for the large, sparse, real, symmetric, and indefinite matrices of the Anderson model of localization. We compare the Lanczos algorithm i

Dongsu Bak, Sang Pyo Kim, Sung Ku Kim, Kwang-Sup Soh

We consider an optical diffraction grating in which the spatial distribution of open slits forms a fractal set. The Fraunhofer diffraction patterns through the fractal grating are obtained analytically for the simplest triad Cantor type and its generalized version. The resulting interference patterns exhibit characteristics of the original fractals and their

Yu. Arestov

RAMPEX - Russian-AMerican Polarization EXperiment - is dedicated to studies of one-spin asymmetries which have twist-3 and also twist-2 origin, in hard and semi-hard inclusive processes on the polarized propane-diol target. A special consideration has been given for the prospects of using polarized 3He target. The studies will be performed at the Serpukhov a

T. Vertse, A. T. Kruppa, R. J. Liotta, W. Nazarewicz

Shell corrections of finite, spherical, one-body potentials are analyzed using a smoothing procedure which properly accounts for the contribution from the particle continuum, i.e., unbound states. Since the plateau condition for the smoothed single-particle energy seldom holds, a new recipe is suggested for the definition of the shell correction. The general

K. Nakayama, A. Szczurek, C. Hanhart, J. Haidenbauer

The production of $ω$-mesons in proton-proton collisions for proton incident energies up to 2.2 GeV is investigated within a meson-exchange model of hadronic interactions. We find a large cancellation between the dominant $πρω$ meson-exchange current and nucleonic current contributions. A comparison with preliminary data from SATURNE calls for the inclusion