July 1997 arXiv papers — page 7

Michael A. Strauss, Jeremiah P. Ostriker, Renyue Cen

The standard method of measuring the galaxy pairwise velocity dispersion on small scales is heavily weighted by the densest regions in a way that is difficult to calibrate. We propose a new statistic which measures the small-scale velocity dispersion as an explicit function of density. Computing this statistic for a volume-limited subsample of the Optical Re

P. Frank Winkler, Knox S. Long

A point X-ray source located 9 arcmin northeast of the center of SN~1006 has been spectroscopically identified as a background QSO, with a redshift of 0.335. The object is moderately bright, with magnitude V=18.3. If its ultraviolet spectrum is typical of low-z quasars, this object will be a second (after the Schweizer-Middleditch star) source to use for abs

C. N. A. Willmer

In this work a comparison between different galaxy luminosity function estimators by means of Monte-Carlo simulations is presented. The simulations show that the C- method of Lynden-Bell (1971) and the STY method derived by Sandage, Tammann & Yahil (1979) are the best estimators to measure the shape of the luminosity function. The simulations also show that

N. V. Ardeljan, G. S. Bisnovatyi-Kogan, S. G. Moiseenko

Results of 2D numerical simulation of magnetorotational mechanism of supernova explosion are presented. It is shown that due to the differential rotation of the star toroidal component of magnetic field appears and grows with time. Angular momentum transfers outwards by the toroidal magnetic field. With the evolution of the process part of the envelope of th

Juri Poutanen, Julian H. Krolik, Felix Ryde

Using simple analytical estimates we show how the physical parameters characterizing different spectral states of the galactic black hole candidates can be determined using spectral data presently available.

V. Bistolas, Y. Hoffman

The linear algorithm of the Wiener filter and constrained realizations (CRs) of Gaussian random fields is extended here to perform non-linear CRs. The procedure consists of: (1) Using low resolution data to constrain a high resolution realization of the underlying field, as if the linear theory is valid; (2) Taking the linear CR backwards in time, by the lin

Emilios T. Harlaftis, Danny Steeghs, Keith Horne, Alexei V. Filippenko

We have reanalyzed Keck observations of Nova Oph 1977 to extend the work done by Filippenko et al. (1997), who recently determined a mass function f(M_x) = 4.86 +/- 0.13 M_o for the compact object. We constrain the rotational broadening, v sin i < 79 km/s, at the 90% confidence level, which gives a mass ratio q < 0.053. The K-type companion star of Nova Oph

A. P. Jones, A. G. G. M. Tielens, D. J. Hollenbach, C. F. McKee

In this paper we discuss the propagation of dust through the interstellar medium (ISM), and describe the destructive effects of stellar winds, jets, and supernova shock waves on interstellar dust. We review the probability that grains formed in stellar outflows or supernovae survive processing in and propagation through the ISM, and incorporate themselves re

Renyue Cen

Gaussian cosmological models, typified by the inflationary cold dark matter models, and non-Gaussian topological defect based cosmological models, such as the texture seeded model, differ in the origin of large-scale cosmic structures. In the former it is believed that peaks at appropriate scales in the initial high density field are the sites onto which mat

M. S. Brotherton, Hien D. Tran, Wil van Breugel, Arjun Dey

We present Keck spectropolarimetry of two rare low-ionization broad absorption line (BAL) QSOs, FIRST J084044.5+363328 and FIRST J155633.8+351758, that also exhibit narrow absorption lines from metastable excited levels of Fe II (``Iron Lo-BALs&#39;&#39;). These QSOs were discovered in optical follow-ups to a deep radio survey; FIRST J155633.8+351758 is radi

D. H. Zanette, A. S. Mikhailov

Large ensembles of globally coupled chaotic neural networks undergo a transition to complete synchronization for high coupling intensities. The onset of this fully coherent behavior is preceded by a regime where clusters of networks with identical activity are spontaneously formed. In these regimes of coherent collective evolution the dynamics of each neural

D. H. Zanette, A. S. Mikhailov

The condensation transition, leading to complete mutual synchronization in large populations of globally coupled chaotic Roessler oscillators, is investigated. Statistical properties of this transition and the cluster structure of partially condensed states are analyzed.

Kenneth J. Mighell

We present our analysis of Hubble Space Telescope Wide Field Planetary Camera 2 observations in F555W (~V) and F814W (~I) of the Carina dwarf spheroidal galaxy. The resulting V vs (V-I) color-magnitude diagrams reach V ~ 27.1 mag. The reddening of Carina is estimated to be E(V-I) = 0.08 +- 0.02 mag. A new estimate of the distance modulus of Carina, (m-M)_0 =

Avinash Khare, Salman Habib, Avadh Saxena

We study the classical thermodynamics of a 1+1-dimensional double-well sinh-Gordon theory. Remarkably, the Schrodinger-like equation resulting from the transfer integral method is quasi-exactly solvable at several temperatures. This allows exact calculation of the partition function and some correlation functions above and below the short-range order (``kink

H. G. Evertz

A review of the Loop Algorithm, its generalizations, and its relation to some other Monte Carlo techniques is given. The loop algorithm is a Quantum Monte Carlo procedure which employs nonlocal changes of worldline configurations, determined by local stochastic decisions. It is based on a formulation of quantum models of any dimension in an extended ensemble

D. T. Frayer, R. L. Brown

We present a general set of calculations decribing the chemical evolution of young massive galaxies and predict the evolution of the CO, O2, and dust abundances as a function of age and metallicity.

V. Barger, Kingman Cheung, K. Hagiwara, D. Zeppenfeld

We perform a global fit of data relevant to $eeqq$ contact interactions, including deep inelastic scattering at high $Q^2$ from ZEUS and H1, atomic physics parity violation in Cesium from JILA, polarized $e^-$ on nuclei scattering experiments at SLAC, Mainz and Bates, Drell-Yan production at the Tevatron, the total hadronic cross section $σ_{had}$ at LEP, an

B. -Q. Ma, S. J. Brodsky

The intrinsic quark-antiquark pairs generated by the minimal energy nonperturbative meson-baryon fluctuations in the nucleon sea provide a consistent framework for understanding a number of empirical anomalies observed in the deep inelastic quark-parton structure of nucleons: the flavor asymmetry of the nucleon sea implied by the violation of Gottfried sum r

B. K. Darian

The spatial gradient expansion of the generating functional was recently developed by Parry, Salopek, and Stewart to solve the Hamiltonian constraint in Einstein-Hamilton-Jacobi theory for gravitationally interacting dust and scalar fields. This expansion is used here to derive an order-by-order solution of the Hamiltonian constraint for gravitationally inte

B. M. Lewis

Gravitational contraction always generates a radially directed momentum flux. A particularly simple example occurs in the electron-degenerate cores of AGB stars, which contract steadily under the addition of helium ashes from shell hydrogen burning. The resulting momentum flux is quantified here. And since the cores of AGB stars lack efficient momentum cance

J. Gegenberg, G. Kunstatter

We explore the relationship between black holes in Jackiw-Teitelboim(JT) dilaton gravity and solitons in sine-Gordon field theory. Our analysis expands on the well known connection between solutions of the sine-Gordon equation and constant curvature metrics. In particular, we show that solutions to the dilaton field equations for a given metric in JT theory

Feike Hacquebord, Herman Verlinde

We study the spectrum of BPS states in N=4 supersymmetric U(N) Yang-Mills theory. This theory has been proposed to describe M-theory on T^3 in the discrete light-cone formalism. We find that the degeneracy of irreducible BPS bound states in this model exhibits a (partially hidden) SL(5,Z) duality symmetry. Besides the electro-magnetic symmetry, this duality

L. Covi, G. Mangano, A. Masiero, G. Miele

A scheme of hybrid inflation is considered in the framework of the minimal supersymmetric SU(5) model with an extra singlet. The relevant role of the cubic term in the adjoint representation in the renormalizable superpotential is pointed out in order to have a quite wide region of initial conditions compatible with inflation efficiency, monopole density and

S. De Martino, S. De Siena, F. Illuminati

The paper has been withdrawn

M. E. Ortiz, F. Vendrell

A quantum mechanical path integral derivation is given of a thermal propagator in non-static Gui spacetime. The thermal nature of the propagator is understood in terms of homotopically non-trivial paths in the configuration space appropriate to tortoise coordinates. The connection to thermal emission from collapsing black holes is discussed.

Mark Wardle

Angular momentum transport in protostellar disks can be achieved by the action of a large scale magnetic field that runs vertically through the disk. The magnetic field centrifugally drives material from the disk surfaces into a wind, initiating a bipolar outflow. One apparent difficulty for this model is that the conductivity of the disk is extremely low in

Anna Sanpera, Rolf Tarrach, Guifre Vidal

We propose an interpretation of quantum separability based on a physical principle: local time reversal. It immediately leads to a simple characterization of separable quantum states that reproduces results known to hold for binary composite systems and which thereby is complete for low dimensions. We then describe a constructive algorithm for finding the ca

J. Rasmussen

In this paper explicit decompositions are provided of the Weyl reflections in affine Lie algebras, in terms of fundamental Weyl reflections.

Oscar Arratia, Francisco J. Herranz, Mariano A. del Olmo

A nonlinear change of basis allows to show that the non-standard quantum deformation of the (3+1) Poincare algebra has a bicrossproduct structure. Quantum universal R-matrix, Pauli-Lubanski and mass operators are presented in the new basis.

M. Rehkopf, V. G. Rostiashvili, T. A. Vilgis

In this paper the Martin-Siggia-Rose formalism is used to derive a generalized Rouse equation for a test chain in a matrix which can undergo the glass transition. It is shown that the surrounding matrix renormalizes the static properties of the test chain. Furthermore the freezing of the different Rouse modes is investigated. This yields freezing temperature

Luca Salasnich

We analyze a spatially homogeneous SU(2) Yang-Mills-Higgs system both in classical and quantum mechanics. By using the Toda criterion of the Gaussian curvature we find a classical chaos-order transition as a function of the Higgs vacuum, the Yang-Mills coupling constant and the energy of the system. Then, we study the nearest-neighbour spacing distribution o

Luca Salasnich

We discuss the role of quantum chaos in atomic nuclei. After reviewing the basic assumptions of the nuclear shell model, we analyze the spectral statistics of the energy levels obtained with realistic shell-model calculations in the fp shell. In particular, for Ca isotopes we observe a transition from order to chaos by increasing the excitation energy and a

B. van de Sande, S. Dalley

We investigate consequences of the effective colour-dielectric formulation of lattice gauge theory using the light-cone Hamiltonian formalism with a transverse lattice (hep-ph/9704408). As a quantitative test of this approach, we have performed extensive analytic and numerical calculations for 2+1-dimensional pure gauge theory in the large $N$ limit. We stud

A. H. Bilge, T. Dereli, S. Kocak

We show that there are no nontrivial solutions of the Seiberg-Witten equations on R^8 with constant standard spin^c structure.

Ali H. Chamseddine, Mikhail S. Volkov

We study static, spherically symmetric, and purely magnetic solutions of SU(2) $\times$ SU(2) gauge supergravity in four dimensions. A systematic analysis of the supersymmetry conditions reveals solutions which preserve 1/8 of the supersymmetries and are characterized by a BPS-monopole-type gauge field and a globally hyperbolic, everywhere regular geometry.

Diana Vaman, Mihai Visinescu

The geodesic motion of pseudo-classical spinning particles in Euclidean Taub-NUT space is analysed. The constants of motion are expressed in terms of Killing-Yano tensors. Some previous results from the literature are corrected.

Carlos Castro

Nottale&#39;s special scale-relativity principle was proposed earlier by the author as a plausible geometrical origin to string theory and extended objects. Scale Relativity is to scales what motion Relativity is to velocities. The universal, absolute, impassible, invariant scale under dilatations in Nature is taken to be the Planck scale, which is not the s

Frank X. Lee

QCD sum rules for the magnetic moments of $Δ^{++}$ and $Ω^-$ are derived using the external field method. They are analyzed by a Monte-Carlo based procedure, using realistic estimates of the QCD input parameters. The results are consistent with the measured values, despite relatively large errors that can be attributed mostly to the poorly-known vacuum susce

Gustavo Burdman

I briefly discuss the derivation of dispersive sum rules constraining semileptonic form-factors. I outline the use of these constraints in the context of charmless semileptonic decays and suggest how, in combination with other theoretical and experimental information, they may reduce the uncertainties in the extraction of $V_{ub}$.

Tarek Ibrahim, Pran Nath

A complete one loop analysis of the chromoelectric dipole contribution to the electric dipole moment (edm) of the quarks and of the neutron in N=1 supergravity including the gluino, chargino and neutralino exchange contributions and exhibiting the dependence on the two CP violating phases allowed in the soft SUSY breaking sector of minimal supergravity model

A. Halprin, C. N. Leung

We derive the character of neutrino oscillations that results from a model of equivalence principle violation suggested recently by Damour and Polyakov as a plausible consequence of string theory. In this model neutrino oscillations will take place through interaction with a long range scalar field of gravitational origin even if the neutrinos are degenerate

A. A. Bolokhov, M. V. Polyakov, S. G. Sherman

We develop the phenomenological amplitude of the $πN \to ππN$ reaction describing the exchanges of $Δ$ and $N_{*}$ along with the OPE mechanism. The contribution of the latter contains 4 independent low energy parameters (up to $O(k^{4})$ order). The terms of the polynomial background are added to stand for far resonances and for contact terms originating fr

H. B. O&#39;Connell, K. Maltman, A. W. Thomas, A. G. Williams

We examine the isospin violation in the timelike pion form factor near threshold at next-to-leading order in the chiral expansion using the techniques of Chiral Perturbation Theory. This next-to-leading order contribution contains the first nonvanishing isospin violation. This isospin violation is found to be very small near threshold. In particular, the iso

Thomas Mehen

Order $β_0^n α_s^{n+1}$ QCD corrections to top quark decays into $W^+$ and $H^+$ bosons are computed to all orders in perturbation theory. Predictions for the radiative corrections to the top quark width are compared with the estimates from BLM scale setting procedures. The results of the summation are shown to greatly improve understanding of higher order c

D0 Collaboration, B. Abbott et al

We have searched for the pair production of first generation scalar leptoquarks in the eejj channel using the full data set (123 pb-1) collected with the D0 detector at the Fermilab Tevatron during 1992--1996. We observe no candidates with an expected background of approximately 0.4 events. Comparing the experimental 95% confidence level upper limit to theor

Steven Rosenberg

This article surveys the relations among local and nonlocal invariants in Atiyah-Singer index theory. We discuss the local invariants that arise from the heat equation approach to the index theorem for geometric operators, as well as the nonlocal invariants (the eta invariant, the determinant of the Laplacian/analytic torsion) that occur in more refined inde

Q. P. Liu, Manuel Mañas

Sequences of Levy transformations for the Darboux system of conjugates nets in multidimensions are studied. We show that after a suitable number of Levy transformations, with at least a Levy transformation in each direction, we get closed formulae in terms of multi-Wroński determinants. These formulae are for the tangent vectors, Lamè coefficients, rotation

M. I. Visscher, B. Rejaei

The effect of the collective charge density wave (CDW) motion on the Josephson current in a superconductor/charge density wave/superconductor junction is studied theoretically. By deriving the kinetic equations for the coupled superconductor-CDW system, it is shown that below the critical current the CDW does not move. Biased above this value, the Josephson

Felix von Oppen

Shot noise in the half-filled Landau level is studied within the composite-fermion picture, focusing on the diffusive regime. The composite fermions are assumed to form a Fermi liquid with nontrivial Fermi-liquid parameters. The Boltzmann-Langevin equation for this system is derived, taking proper account of fluctuations in both the Chern-Simons and the phys

Klaus Doll, Hermann Stoll

We calculate cohesive properties of LiF, NaF, KF, LiCl, NaCl, and KCl with ab-initio quantum chemical methods. The coupled-cluster approach is used to correct the Hartree-Fock crystal results for correlations and to systematically improve cohesive energies, lattice constants and bulk moduli. After inclusion of correlations, we recover 95-98 % of the total co

M. S. Tomassone, J. B. Sokoloff, A. Widon, J. Krim

We perform molecular dynamics simulations of friction for atomically thin Xe films sliding on Ag(111). We determine the inverse of the coefficient of friction (i.e. slip time) by direct calculation of the decay of the center of mass velocity after applying an external force, as well as from the velocity autocorrelation function. We find that the slip time ex

M. I. Visscher, B. Rejaei

We investigate theoretically the collective charge density wave motion through an ensemble of small disordered Aharonov-Bohm rings. It is shown that the magnetic flux modulates the threshold field and the magnetoresistance with a half flux quantum periodicity $Φ_{0}/2=h/2e$, resulting from ensemble averaging over random scattering phases of multiple rings. T

A. N. Samukhin, V. N. Prigodin, L. Jastrabik

Polymer&#39;s network is treated as an anisotropic fractal with fractional dimensionality D = 1 + εclose to one. Percolation model on such a fractal is studied. Using the real space renormalization group approach of Migdal and Kadanoff we find threshold value and all the critical exponents to be strongly nonanalytic functions of ε, e.g. the critical exponent

T. J. Hagenaars, E. H. Brandt

We study the effect of a transport current on the vortex-line lattice in isotropic type-II superconductors in the presence of strong thermal fluctuations by means of &#39;driven-diffusion&#39; Monte Carlo simulations of a discretized London theory with finite magnetic penetration depth. We calculate the current-voltage (I-V) characteristics for various tempe

Mulugeta Bekele, G. Ananthakrishna

We consider a model proposed by one of the authors for a type of plastic instability found in creep experiments which reproduces a number of experimentally observed features. The model consists of three coupled non-linear differential equations describing the evolution of three types of dislocations. The transition to the instability has been shown to be via

G. George Batrouni, Alex Hansen

We report on large scale numerical simulations of fracture surfaces using random fuse networks for two very different disorders. There are some properties and exponents that are different for the two distributions, but others, notably the roughness exponents, seem universal. For the universal roughness exponent we found a value of zeta = 0.62 +/- 0.05. In co

Martin Volk, Dirk Richarz

In this paper we describe our experiences with a tool for the development and testing of natural language grammars called GTU (German: Grammatik-Testumgebumg; grammar test environment). GTU supports four grammar formalisms under a window-oriented user interface. Additionally, it contains a set of German test sentences covering various syntactic phenomena as

R. O. Grigoriev, M. C. Cross

Symmetry properties of the evolution equation and the state to be controlled are shown to determine the basic features of the linear control of unstable orbits. In particular, the selection of control parameters and their minimal number are determined by the irreducible representations of the symmetry group of the linearization about the orbit to be controll

L. Biferale, D. Pierotti, F. Toschi

Helicity transfer in a shell model of turbulence is investigated. We show that a Reynolds-independent helicity flux is present in the model when the large scale forcing breaks inversion symmetry. The equivalent in Shell Models of the ``2/15 law&#39;&#39;, obtained from helicity conservation in Navier-Stokes eqs., is derived and tested. The odd part of helici

Valerio Faraoni

Gravitational waves act like lenses for the light propagating through them. This phenomenon is described using the vector formalism employed for ordinary gravitational lenses, which was proved to be applicable also to a non-stationary spacetime, with the appropriate modifications. In order to have multiple imaging, an approximate condition analogous to that

Z. Kollath, J. R. Buchler, J. P. Beaulieu, M. J. Goupil

The Fourier spectral analysis of this object suggests a nonlinear pulsation of period approximately 14d with a 3:2 frequency lock between two vibrational modes. We discuss an extensive search that we have performed in the L, M, Teff space for models of period 14 - 16 days that exhibit this particular resonance. We find models satisfying the resonance constra

Alan Dressler, Augustus Oemler,, Warrick J. Couch, Ian Smail

Using traditional morphological classifications of galaxies in 10 intermediate-redshift (z~0.5) clusters observed with WFPC-2 on the Hubble Space Telescope, we derive relations between morphology and local galaxy density similar to that found by Dressler for low-redshift clusters. Taken collectively, the `morphology-density&#39; relationship, M-D, for these

Ian Smail, Alastair C. Edge, Richard S. Ellis, Roger D. Blandford

We present a deep UBI CCD survey using the Palomar 5-m telescope of a sample of high X-ray luminosity, distant clusters selected from the ROSAT All-Sky Survey. The 10 clusters lie at z=0.22-0.28, an era where evolutionary effects have been reported in the properties of cluster galaxy populations. Our clusters thus provide a well-defined sample of the most ma

K. Sumiyoshi, S. Yamada, H. Suzuki, W. Hillebrandt

First results of numerical simulations are presented which compute the dynamical evolution of a neutron star with a mass slightly below the minimum stable mass by means of a new implicit (general relativistic) hydrodynamic code. We show that such a star first undergoes a phase of quasi-static expansion, caused by slow nuclear $β$-decays, lasting for about 20

M. Sekiguchi, M. Fukugita

We point out that the absolute magnitude of the Galactic Cepheids, which have been used for local calibrations for Cepheid period-luminosity relation, shows an unexpectedly large metal abundance effect. This indicates that either Cepheids period luminosity relation has a large metallicity dependence, much larger than expected in stellar pulsation models, or

D. Ghilencea, M. Lanzagorta, G. G. Ross

The unification of gauge couplings suggests that there is an underlying (supersymmetric) unification of the strong, electromagnetic and weak interactions. The prediction of the unification scale may be the first quantitative indication that this unification may extend to unification with gravity. We make a precise determination of these predictions for a cla

Witold Pokorski, Graham G. Ross

We consider the phenomenological implications of a class of compactified string theories which naturally reproduces the flavour multiplet structure of the Standard Model. The implications for gauge unification depends on which of three possibilities is realised for obtaining light Higgs multiplets. The more conventional one leads to predictions for the gauge

Victor A. Gopar, Pier A. Mello

We show that the study of the statistical properties of the scattering matrix S for quantum chaotic scattering in the presence of direct processes (charaterized by a nonzero average S matrix <S>) can be reduced to the simpler case where direct processes are absent (<S> = 0). Our result is verified with a numerical simulation of the two-energy autocorrelation

Hoi-Kwong Lo, Sandu Popescu

Suppose two distant observers Alice and Bob share a pure bipartite quantum state. By applying local operations and communicating with each other using a classical channel, Alice and Bob can manipulate it into some other states. Previous investigations of entanglement manipulations have been largely limited to a small number of strategies and their average ou

Fritz Gesztesy, Helge Holden

We derive a zero-curvature formalism for a combined sine-Gordon (sG) and modified Korteweg-de Vries (mKdV) equation which yields a local sGmKdV hierarchy. In complete analogy to other completely integrable hierarchies of soliton equations, such as the KdV, AKNS, and Toda hierarchies, the sGmKdV hierarchy is recursively constructed by means of a fundamental p

H. -P. Pavel, D. Blaschke, G. Röpke, V. N. Pervushin

We discuss how the presence of a squeezed gluon vacuum might lead to quark confinement in the framework of the global colour model of QCD. Using reduced phase space quantization of massive vector theory we construct a Lorentz invariant and colourless squeezed gluon condensate and show that it induces a permanent, nonlocal quark interaction (delta-function in

D. Han, Y. S. Kim, Marilyn E. Noz

It is noted that the Jones-matrix formalism for polarization optics is a six-parameter two-by-two representation of the Lorentz group. It is shown that the four independent Stokes parameters form a Minkowskian four-vector, just like the energy-momentum four-vector in special relativity. The optical filters are represented by four-by-four Lorentz-transformati

Hou Defu, Li Jiarong

By considering the Debye screening and damping rate of gluons, the viscosity coefficient of the quark-gluon plasma was evaluated via real-time finite temperature QCD in the relaxation time approximation at finite temperature and chemical potential . The results show that both the damping rate and the chemical potential cause considerable enhancements to the

S. Lupi, M. Capizzi, P. Calvani, B. Ruzicka

Reflectance measurements in properly selected samples of Nd$_{1.96}$Ce$_{0.04}$CuO$_{4+y}$ with different carrier concentrations provide a firm evidence of Fano antiresonances for the four transverse optical $E_u$ phonons in the $a-b$ plane. Fits performed without any previous subtraction of the electronic background, as well as the dependence on temperature

H. M. Antia

Frequency and rotational splittings of the solar f-modes are estimated from the GONG data. Contrary to earlier observations the frequencies of f-modes are found to be close to the theoretically computed values for a standard solar model. The f-mode being essentially a surface mode is a valuable diagnostic probe of the properties of the solar surface, and als

C. Alcock et al

We identify the likely optical counterpart to the LMC supersoft X-ray source RXJ0527.8-6954, and hence recover HV2554. This identification is based on an analysis of approximately 4 years of optical photometry obtained serendipitously via the MACHO project. We see a steady fading of the star of about 0.5 mag over the duration of the observations. Evidence is

Michael Isenberg, D. Q. Lamb, John C. L. Wang

We calculate the properties of gamma-ray burst spectral lines formed by resonant cyclotron scattering in a radiation-driven outflow. Most previous models of line formation in gamma-ray bursts are appropriate at the polar cap of a neutron star located no further than several hundred parsecs away. However, the BATSE brightness and sky distributions indicate th

K. Young

The 609u 3P1 -> 3P0 line of neutral atomic carbon has been detected in the protoplanetary nebulae CRL 618 and CRL 2688. CI appears to be about 7% as abundant as CO in CRL 2688, and 70% as abundant as CO in CRL 618. CI emission arises primarily from the slow component of the wind from these objects. The data presented here indicate that CI gradually becomes m

F. K. Sutaria, A. Ray

Neutrinos emitted during stellar core collapse up to their trapping phase carry information about the stage from which the Supernova explosion process initiates. The dominant $ν_e$ emission mechanism is by electron capture on free protons and f-p shell nuclei and the spectrum of these neutrinos is a function of the ambient physical conditions within the core

L. Baulieu, A. Losev, N. Nekrasov

We describe special supersymmetric gauge theories in three, five, seven and nine dimensions, whose compactification on two-, four-, six- and eight-folds produces a supersymmetric quantum mechanics on moduli spaces of holomorphic bundles and/or solutions to the analogues of instanton equations in higher dimensions. The theories may occur on the worldvolumes o

A. R. Rastegar, M. R. Rahimi Tabar, P. Hawaii

We investigate exact results of isotropic turbulence in three-dimensions when the pressure gradient is negligible. We derive exact two-point correlation functions of density in three-dimensions and show that the density-density correlator behaves as $ |{x_1 - x_2}|^{-\alpha_3}$, where $\alpha_3 = 2 + \frac{\sqrt{33}}{6}$. It is shown that, in three-dimension

Klaus M. Frahm

Using the supersymmetry technique, we analytically derive the recent result of Casati, Maspero and Shepelyansky [cond-mat/9706103] according to which the quantum dynamics of open chaotic systems follows the classical decay up to a new quantum relaxation time scale $t_q\sim\sqrt{t_c t_H}$. This scale is larger than the classical escape time $t_c$ but still mu

Sven Bergmann

We study the effects of flavor changing neutrino interactions on the resonant conversion of solar neutrinos. In particular, we describe how the regions in the $Delta m^2 - sin^2 2theta$ plane that are consistent with the four solar neutrino experiments are modified for different strengths of New Physics neutrino interactions.

Kazuo Fujikawa, Harunobu Kubo

It is shown that an extended q-deformed $su(2)$ algebra with an extra (``Schwinger &#39;&#39;) term can describe Bloch electrons in a uniform magnetic field with an additional periodic potential. This is a generalization of the analysis of Bloch electrons by Wiegmann and Zabrodin. By using a representation theory of this q-deformed algebra, we obtain functio

James V. Steele, Hidenaga Yamagishi, Ismail Zahed

We discuss an on-shell approach to pion-nucleon physics that is consistent order by order in a $1/f_π$ expansion with the chiral reduction formula, crossing, and relativistic unitarity. A number of constraints between the on-shell low-energy parameters are derived at tree level in the presence of the pion-nucleon sigma term, and found to be in fair agreement

Burkhard Kleihaus, Jutta Kunz

We discuss the static axially symmetric regular solutions, obtained recently in Einstein-Yang-Mills and Einstein-Yang-Mills-dilaton theory [1]. These asymptotically flat solutions are characterized by the winding number $n>1$ and the node number $k$ of the purely magnetic gauge field. The well-known spherically symmetric solutions have winding number $n=1$.

I-Ching Yang, Wei-Fui Lin, Rue-Ron Hsu

Using Møller&#39;s energy complex, we obtain the energy distributions of GHS solution and dyonic dilaton black hole solution in the dilaton gravity theory. It is confirmed that the Møller&#39;s energy complex is indeed a 3-scalar under purely spatial transformation in these energy distributions. Some interested properties of the energy distribution of dyonic

Maria Morandi Cecchi, Luca Salasnich

In this paper we analyze the convergence of the splitting method for shallow water equations. In particular, we give an analytical estimation of the time step which is necessary for the convergence and then we study the behaviour of the motion of the shallow water in the Venice lagoon by using the splitting method with a finite element space discretization.

Sergio Doplicher, Claudia Pinzari, Rita Zuccante

We regard a right Hilbert C*-module X over a C*-algebra A endowed with an isometric *-homomorphism ϕ: A\to L_A(X) as an object X_A of the C*-category of right Hilbert A-modules. Following a construction by the first author and Roberts, we associate to it a C*-algebra O_{X_A} containing X as a ``Hilbert A-bimodule in O_{X_A}&#39;&#39;. If X is full and finite

Ajanta Bhowal

We have studied the damage spreading (defined in the text) in the &#39;sandpile&#39; model of self organised criticality. We have studied the variations of the critical time (defined in the text) and the total no of sites damaged at critical time as a function of system size. Both shows the power law variation.

M. H. Hettler, J. Kroha, S. Hershfield

The M-channel Anderson impurity model (M=1,2) is studied in the Kondo limit with a finite voltage bias applied to the conduction electron reservoirs. Using the Non-Crossing Approximation (NCA), we calculate the local spectral functions, the differential conductance, and susceptibility at non-zero bias for symmetric as well as asymmetric coupling of the impur

J. Oswald

This is a comment on a paper published by J.E. Mueller in Phys. Rev. Lett. 72, 2616 (1994).

J. Piekarewicz, J. R. Shepard

We employ the recently proposed plaquette basis to investigate static and dynamic properties of isotropic 2-leg Heisenberg spin ladders. Simple non-interacting multi-plaquette states provide a remarkably accurate picture of the energy/site and dynamic spin response of these systems. Insights afforded by this simple picture suggest a very efficient truncation

C. S. Reynolds, M. C. Begelman

We suggest that extragalactic radio sources are intermittent on timescales of 10^4-10^5 yr. Using a simple spherical model of a cocoon/shock system, it is found that inactive sources fade rapidly in radio luminosity but the shock in the ambient medium continues to expand supersonically, thereby keeping the whole source structure intact during the inactive ph

A. Ray, F. K. Sutaria, J. Sheikh

We present the spectra of pre trapping neutrinos emitted from a core collapse supernova (having main sequence masses 15 and 25 $M_{\sun}$) within 1 kpc which can be detected by terrestrial detectors. The neutrino spectrum depends on the abundance of nuclei and free protons which undergo electron capture which in turn is determined by nuclear properties of th

E. Dagotto, G. B. Martins, J. Riera, A. L. Malvezzi

A method is proposed to improve the accuracy of approximate techniques for strongly correlated electrons that use reduced Hilbert spaces. As a first step, the method involves a change of basis that incorporates exactly part of the short distance interactions. The Hamiltonian is rewritten in new variables that better represent the physics of the problem under

A. A. Koulakov, B. I. Shklovskii

Charging of a clean two-dimensional island is studied in the regime of small concentration of electrons when they form the Wigner crystal. Two forms of electron-electron interaction potential are studied: the pure Coulomb interaction and the exponential interaction corresponding to the screening by a pair of close metallic gates. The electrons are assumed to

F. Leblond, L. Marleau

The spherically symmetric hedgehog ansatz used in the description of the skyrmion is believed to be inadequate for the rotational states such as the nucleon (I=J=1/2) and the Delta (I=J=3/2) due to centrifugal forces. We study here a simple alternative: an oblate spheroidal solution which leads to lower masses for these baryons. As one might expect, the shap

Shimon Levit, Dror Orgad

This paper is presently under revision and amendments. It will be posted soon.

Giampiero Esposito, Alexander Yu. Kamenshchik, Klaus Kirsten

The zero-point energy of a conducting spherical shell is evaluated by imposing boundary conditions on the potential, and on the ghost fields. The scheme requires that temporal and tangential components of perturbations of the potential should vanish at the boundary, jointly with the gauge-averaging functional, first chosen of the Lorenz type. Gauge invarianc