January 2000 arXiv papers — page 13

T. A. Trainor

Event-by-event analysis of heavy-ion collision events is an important tool for the study of the QCD phase boundary and formation of a quark-gluon plasma. A universal feature of phase boundaries is the appearance of increased fluctuations of conserved measures as manifested by excess measure variance compared to a reference. In this paper I consider a particu

Ayse Kizilersu, Tom Sizer, Anthony G. Williams

We consider procedures through which an ultraviolet cut-off regularization scheme can be modified to reproduce the same results for nonperturbative renormalized Green's functions as obtained from a dimensional regularization scheme. These issues are considered within the Dyson-Schwinger equation framework, where ultraviolet cut-off regularization can lea

Wojciech Krolikowski

A four-neutrino effective texture is described, where a sterile neutrino mixes nearly maximally with the electron neutrino and so, is responsible for the deficit of solar $ν_e $'s (according to the large-angle MSW solution or vacuum solution, of which the former is selected a posteriori). But, while maximal mixing of muon neutrino with tauon neutrino cau

Ivan Horvath

Several issues related to the question "How simple can Ginsparg-Wilson fermionic actions be?" are discussed, and it is suggested that simplicity in the eigenspace should be looked for.

Artan Borici

I describe a Lanczos method to compute the Neuberger Operator and a multigrid algorithm for its inversion.

OLYA, MD-1 Collaborations, :, A. S. Artamonov

High precision mass measurements in $Ψ$ and $Υ$ families performed in 1980-1984 at the VEPP-4 collider with OLYA and MD-1 detectors are revisited. The corrections for the new value of the electron mass are presented. The effect of the updated radiative corrections has been calculated for the $J/Ψ(1S)$ and $Ψ(2S)$ mass measurements.

J. Podolsky, J. B. Griffiths

The Penrose method for constructing spherical impulsive gravitational waves is investigated in detail, including alternative spatial sections and an arbitrary cosmological constant. The resulting waves include those that are generated by a snapping cosmic string. The method is used to construct an explicit exact solution of Einstein's equations describin

Lars Andersson, Alan D. Rendall

The most detailed existing proposal for the structure of spacetime singularities originates in the work of Belinskii, Khalatnikov and Lifshitz. We show rigorously the correctness of this proposal in the case of analytic solutions of the Einstein equations coupled to a scalar field or stiff fluid. More specifically, we prove the existence of a family of space

C. Gundlach

As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term ``critical phenomena''. They are explained by the existence of exact solutions wh

Warren G. Anderson, Patrick R. Brady, Jolien D. E. Creighton, Eanna E. Flanagan

We present a filter for detecting gravitational wave signals from burst sources. This filter requires only minimal advance knowledge of the expected signal: i.e. the signal's frequency band and time duration. It consists of a threshold on the total power in the data stream in the specified signal band during the specified time. This filter is optimal (in

Mona Berciu, Sajeev John

We investigate a microscopic model for strongly correlated electrons with both on-site and nearest neighbor Coulomb repulsion on a 2D square lattice. This exhibits a state in which electrons undergo a ``somersault'' in their internal spin-space (spin-flux) as they traverse a closed loop in external coordinate space. When this spin-1/2 antiferromagnet

W. Wernsdorfer, A. Caneschi, R. Sessoli, D. Gatteschi

The strong influence of nuclear spins on resonant quantum tunneling in the molecular cluster Fe_8 is demonstrated for the first time by comparing the relaxation rate of the standard Fe_8 sample with two isotopic modified samples: (i) 56_Fe is replaced by 57_Fe, and (ii) a fraction of 1_H is replaced by 2_H. By using a recently developed "hole digging&#34

A. Kudrolli, J. Henry

The velocity distribution of spheres rolling on a slightly tilted rectangular two dimensional surface is obtained by high speed imaging. The particles are excited by periodic forcing of one of the side walls. Our data suggests that strongly non-Gaussian velocity distributions can occur in dilute granular materials even in the absence of significant density c

C. Castellani, C. Di Castro, M. Grilli, A. Perali

The evidence of edge-gaps around the M-points in the metallic state of underdoped cuprates has triggered a very active debate on their origin. We first consider the possibility that this spectroscopic feature results from a quasi-static charge ordering taking place in the underdoped regime. It comes out that to explain the coexistence of gaps and arcs on the

C. Di Castro, L. Benfatto, S. Caprara, C. Castellani

We elaborate on several observable consequences of the Quantum-Critical-Point scenario. In particular we show that the strong k-dependent scattering of the quasiparticles with the quasi-critical charge and spin fluctuations reproduces the main features of the low-energy spectral weights and of the observed Fermi surfaces. In the underdoped cuprates the attra

Yves-Patrick Pellegrini

An effective-medium theory is proposed for random weakly nonlinear dielectric media. It is based on a new gaussian approximation for the probability distributions of the electric field in each component of a multi-phase composite. These distributions are computed to linear order from a Bruggeman-like self-consistent formula. The resulting effective-medium fo

M. Fabrizio, A. O. Gogolin, A. A. Nersesyan

We study the properties of the double-frequency sine--Gordon model in the vicinity of the Ising quantum phase transition displayed by this model. Using a mapping onto a generalised lattice quantum Ashkin-Teller model, we obtain critical and nearly-off-critical correlation functions of various operators. We discuss applications of the double-sine-Gordon model

Angel Rubio, S. Peter Apell, Liesbeth C. Venema, Cees Dekker

We discuss the local cutting of single-walled carbon nanotubes by a voltage pulse to the tip of a scanning tunneling microscope. The tip voltage ($\mid V \mid \ge $~3.8 eV) is the key physical quantity in the cutting process. After reviewing several possible physical mechanisms we conclude that the cutting process relies on the weakening of the carbon-carbon

Elad Tomer, Leonid Safonov, Shlomo Havlin

A new single lane car following model of traffic flow is presented. The model is inertial and free of collisions. It demonstrates experimentally observed features of traffic flow such as the existence of three regimes: free, fluctuative (synchronized) and congested (jammed) flow; bistability of free and fluctuative states in a certain range of densities, whi

Yves-Patrick Pellegrini, Marc Barthelemy

We study effective-medium approximations for linear composite media by means of a path integral formalism with replicas. We show how to recover the Bruggeman and Hori-Yonezawa effective-medium formulas. Using a replica-coupling ansatz, these formulas are extended into new ones which have the same percolation thresholds as that of the Bethe lattice and Potts

O. Hilt, H. B. Brom, M. Ahlskog

We measured the complex dielectric constant in mats of single-wall carbon-nanotubes between 2.7 K and 300 K up to 0.5 THz. The data are well understood in a Drude approach with a negligible temperature dependence of the plasma frequency (omega_p) and scattering time (tau) with an additional contribution of localized charges. The dielectric properties resembl

S. Okamoto, S. Ishihara, S. Maekawa

Correlation between orbital structure and magnetic ordering in bilayered manganites is examined. A level separation between the $3d_{3z^2-r^2}$ and $3d_{x^2-y^2}$ orbitals in a Mn ion is calculated in the ionic model for a large number of the compounds. It is found that the relative stability of the orbitals dominates the magnetic transition temperatures as

Masao Iwamatsu, Yutaka Okabe

A new Monte Carlo scheme based on the system of Tsallis's generalized statistical mechanics is applied to a simple double well potential to calculate the canonical thermal average of potential energy. Although we observed serious quasi-ergodicity when using the standard Metropolis Monte Carlo algorithm, this problem is largely reduced by the use of the n

F. Legrand, D. Kunth, J. -R. Roy, J. M. Mas-Hesse

Deep long-slit spectroscopic observations of the blue compact galaxy IZw 18 obtained with the CFH 3.6 m Telescope are presented. The very low value of oxygen abundance previously reported is confirmed and a very homogeneous abundance distribution is found (no variation larger than 0.05 dex) over the whole ionized region. We concur with Tenorio-Tagle (1996) a

Heinz Voelk

In this talk I will first give a summary of the observations of expected Galactic TeV gamma-ray sources with the HEGRA CT-Sytem since the Kruger Park Workshop in 1997. Then I will go into some detail regarding the observations of Supernova Remnants (SNRs), especially those of Tycho's SNR and of Cas A. The emphasis will not be on all aspects of these publ

T. J. Galama, A. G. De Bruyn

Radio observations with the Square Kilometer Array (SKA) provide the agility, sensitivity, and spectral coverage to trace the evolution of the size, shape and spectra of gamma-ray burst (GRB) remnants from the earliest moments on. In the first hours to days after the burst a major, and unique tool, will be provided through the study of dynamically evolving r

Shai Kaspi, W. N. Brandt, Donald P. Schneider

We report on a search for X-ray emission from quasars with redshifts greater than four using the ROSAT public database. Our search has doubled the number of z>4 quasars detected in X-rays from 6 to 12. Most of those known prior to this work were radio-loud and X-ray selected sources; our study increases the number of X-ray detected, optically selected z>4 qu

D. C. Homan, J. F. C. Wardle

We present a new technique for directly measuring the distances to superluminal radio sources. By comparing the observed proper motions of components in a parsec scale radio jet to their measured Doppler factors, we can deduce the distance to the radio source independent of the standard rungs in the cosmological distance ladder. This technique requires that

Miguel A. de Avillez

Three-dimensional simulations of the disk-halo interaction show the formation of a thick HI and HII gas disk with different scale heights. The thick HI disk prevents the disk gas from expanding freely upwards, unless some highly energetic event such as chimneys occurs, whereas the thick HII disk acts as a disk-halo interaction region from where the hot ioniz

Paul P. van der Werf

Observations and interpretation of extragalactic rotational and rovibrational H2 emission are reviewed. Direct observations of H2 lines do not trace bulk H2 mass, but excitation rate. As such, the H2 lines are unique diagnostics, if the excitation mechanism can be determined, which generally requires high-quality spectroscopy and suitable additional data. Th

J. R. Hurley, O. R. Pols, C. A. Tout

We present analytic formulae that approximate the evolution of stars for a wide range of mass and metallicity. Stellar luminosity, radius and core mass are given as a function of age, M and Z, for all phases from the zero-age main-sequence up to, and including, the remnant stages. For the most part we find continuous formulae accurate to within 5% of detaile

Sarbani Basu, H. M. Antia

Using data from the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory (SOHO), we study the large-scale velocity fields in the outer part of the solar convection zone using the ring diagram technique. We use observations from four different times to study possible temporal variations in flow velocity. We find definite c

H. M. Antia, Sarbani Basu, J. Pintar, B. Pohl

Using data from the Global Oscillation Network Group (GONG) covering the period from 1995 to 1998, we study the change with solar activity in solar f-mode frequencies. The results are compared with similar changes detected from the Michelson Doppler Imager (MDI) data. We find variations in f-mode frequencies which are correlated with solar activity indices.

S. Phleps, K. Meisenheimer, B. Fuchs, C. Wolf

In this paper we present the first results of deep star counts carried out within the Calar Alto Deep Imaging Survey, CADIS (Meisenheimer 1998). Although CADIS was designed as an extragalactic survey, it also attempts to identify the stars in the fields in order to avoid confusion with quasars and compact galaxies. We have identified a sample of about 300 fa

D. Bizyaev, A. Zasov, S. Kajsin

We present the results of BVRI photometry of two galaxies with active star formation: NGC 834 and NGC 1134. Combined color index Q_{BVI} was used to investigate the photometrical structure of the galaxies. Index Q_{BVI} is not affected by internal extinction and is sensitive to the presence of blue stars. Ring-like region with active star formation at 15" fr

M. Akiyama, K. Ohta, T. Yamada, N. Kashikawa

We present results of optical identification of the X-ray sources detected in the ASCA Large Sky Survey. Optical spectroscopic observations were done for 34 X-ray sources which were detected with the SIS in the 2-7 keV band above 3.5 sigma. The sources are identified with 30 AGNs, 2 clusters of galaxies, and 1 galactic star. Only 1 source is still unidentifi

Y. P. Jing, Yasushi Suto

We report a series of high-resolution N-body simulations designed to examine the internal physical properties of dark matter halos. A total of fifteen halos, each represented by $\sim 1$ million particles within the virial radius, have been simulated covering the mass range of $2\times10^{12}\sim 5\times10^{14} h^{-1}{\rm M_\odot}$. As the first application

Chao Yuan Yang

Pioneer-10 unexpected anomalous deceleration hurtling through the solar system might have revealed a secret of nature that gravitational information propagating at very high but finite speed rushing to gravitational horizon opens a window to Universe neighborhood. Dark energy may be owing to interactive gravitational horizons of cousin universes. The necessa

Chris Quigg

I quickly review the successes of quantum chromodynamics. Then I assess the current state of the electroweak theory, making brief comments about the search for the Higgs boson and some of the open issues for the theory. I sketch the problems of mass and mass scales, and point to a speculative link between the question of identity and large extra dimensions.

X. M. Liu, M. Hug, G. J. Milburn

We consider continuous observation of the nonlinear dynamics of single atom trapped in an optical cavity by a standing wave with intensity modulation. The motion of the atom changes the phase of the field which is then monitored by homodyne detection of the output field. We show that the conditional Hilbert space dynamics of this system, subject to measureme

Yong-Wan Kim, Young-Jai Park, Kwang-Sup Soh

We obtain a (5+2)-dimensional global flat embedding of the (3+1)-dimensional curved RN-AdS space. Our results include the various limiting cases of global embedding Minkowski space (GEMS) geometries of the RN, Schwarzschild-AdS in (5+2)-dimensions, Schwarzschild in (5+1)-dimensions, purely charged space, and universal covering space of AdS in (4+1)-dimension

L. Vaidman

Byrne and Hall (1999) criticized the argument of Chalmers (1996) in favor of the Everett-style interpretation. They claimed to show ``the deep and underappreciated flaw in ANY Everett-style interpretation''. I will argue that it is possible to interpret Chalmers's writing in such a way that most of the criticism by Byrne and Hall does not apply.

Alejandro Rivero

We recall the origins of differential calculus from a modern perspective. This lecture should be a victory song, but the pain makes it to sound more as an oath for vendetta, coming from Syracuse two milenia before.

Igor Pavlichenkov

The quasiclassically exact solution for the second inertial parameter $\cal B$ is found in self-consistent way. It is shown that superdeformation and nonuniform pairing arising from the rotation induced pair density significantly reduce this inertial parameter. The different limiting cases for $\cal B$, which allow to study an interplay between rapid rotatio

Mahendra Jani, Robert G. Rieper

We find a generating function expressed as a continued fraction that enumerates ordered trees by the number of vertices at different levels. Several Catalan problems are mapped to an ordered-tree problem and their generating functions also expressed as a continued fraction. Among these problems is the enumeration of (132)-pattern avoiding permutations that h

Mikhail S. Plyushchay

We review the construction of minimally bosonized supersymmetric quantum mechanics and its relation to hidden supersymmetries in pure parabosonic (parafermionic) systems.

C. Bachas

I review the arguments in favor of/against the traditional hypothesis that the Planck, string and compactification scales are all within a couple of orders of magnitude from each other. I explain how the extreme brane-world scenario, with TeV type I scale and two large (near millimetric) transverse dimensions, creates conditions analogous to those of the ene

Takahiro Tanaka, Xavier Montes

We present a complete scheme to discuss linear perturbations in the two-branes model of the Randall and Sundrum scenario with the stabilization mechanism proposed by Goldberger and Wise. We confirm that under the approximation of zero mode truncation the induced metric on the branes reproduces that of the usual 4-dimensional Einstein gravity. We also present

P. Baseilhac, D. Reynaud

The dual relationship between two n-1 parameter families of quantum field theories based on extended complex numbers is investigated in two dimensions. The non-local conserved charges approach is used. The lowest rank affine Toda field theories are generated and identified as integrability submanifolds in parameter space. A truncation of the model leads to a

Fu-Guang Cao, A. I. Signal

We point out that charge symmetry violation in both the valence and sea quark distributions of the nucleon has a non-perturbative source. We calculate this non-perturbative charge symmetry violation using the meson cloud model, which has earlier been successfully applied to both the study of SU(2) flavour asymmetry in the nucleon sea and quark-antiquark asym

Mitsuru Ooho, Kiyoshi Shiraishi

We find an exact solution for multi-black strings in the brane world with warped compactification.

H. C. Rosu

The main theme of this survey is the equivalence statements for quantum scalar field vacuum states that have been recognized over the last couple of decades as a powerful line of reasoning when discussing the highly academic thermal-like Hawking effect and Unruh effect. An important ingredient in this framework is the concept of vacuum field noise spectrum b

Sung-Sik Lee, Sung-Ho Suck Salk

Using the t-J Hamiltonian of U(1) slave-boson symmetry, bose condensation is discussed by showing the occurrence of symmetry breaking in the hole doped high $T_c$ cuprates. The symmetry breaking is shown to take place with the d-wave hole pairing, but not with the s-wave hole pairing. Based on a derived supersymmetry Hamiltonian we find that there exists a p

E. Akkermans, K. Mallick

We study the Ginzburg-Landau equations in order to describe a two-dimensional superconductor in a bounded domain. Using the properties of a particular integrability point ($κ= 1/ \sqrt2$) of these nonlinear equations which allows vortex solutions, we obtain a closed expression for the energy of the superconductor. The presence of the boundary provides a sele

Sung-Sik Lee, Sung-Ho Suck Salk

We investigate a possibility of holon pairing for bose condensation based on the Bethe-Salpeter equation obtained from the use of the t-J Hamiltonians of both t he U(1) and SU(2) slave-boson symmetries. It is shown that the vertex function contributed from ladder diagram series involving holon-holon scattering channel in the Bethe-Salpeter equation leads to

Oron Zachar

For stripes of hole rich lines in doped antiferromagnets, we investigate the competition between anti-phase and in-phase domain wall ground state configurations. We argue that a phase transition must occure as a function of the electron/hole filling fraction of the domain wall. Due to {\em transverse} kinetic hole fluctuations, empty domain walls are always

R. Coziol, S. Considere, E. Davoust, T. Contini

We have proposed in a companion paper (Considere et al. 2000) that bars appeared recently in massive starburst nucleus galaxies. We now test this hypothesis on an extended sample of barred and unbarred Markarian starburst galaxies, using several samples of normal galaxies as control samples. In support of this hypothesis, we show that the proportion of barre

S. Considere, R. Coziol, T. Contini, E. Davoust

The oxygen (O/H) and N/O abundance ratios along the bar of 16 barred spiral starburst galaxies are determined using long-slit spectroscopy. The abundance gradients and the spatial distribution of the ionized gas along the bar are used to understand the role of bars in starburst galaxies. The oxygen abundance gradients are steeper than in normal barred galaxi

Richard G. McMahon, N. A. Walton, M. J. Irwin, J. R. Lewis

The 2.5m Isaac Newton Telescope(INT) is currently being used to carry out a major multi-colour, multi-epoch, CCD based wide field survey over an area of 100 square degrees. The survey parameters have been chosen to maximise scientific return over a wide range of scientific areas and to complement other surveys being carried out elsewhere. Unique aspects of t

T. Mazeh, D. Naef, G. Torres, D. W. Latham

We report a spectroscopic orbit with period P = 3.52433 +/- 0.00027 days for the planetary companion that transits the solar-type star HD209458. For the metallicity, mass, and radius of the star we derive [Fe/H] = 0.00 +/- 0.02, M = 1.1 +/- 0.1 solar masses, and R = 1.3 +/- 0.1 solar radii. This is based on a new analysis of the iron lines in our HIRES templ

Mordehai Milgrom, Vladimir V. Usov

We propose that a gamma-ray burst in one member of a binary may induce a supernova-like explosion of a close, white-dwarf companion. Such an explosion might be brought about in rather light companions, which cannot undergo the standard accretion-induced explosion. This would give some GRB-associated supernova an appearance rather unlike that of the typical T

Shay Zucker, Tsevi Mazeh

HD10697 is a nearby main-sequence star around which a planet candidate has recently been discovered by means of radial-velocity measurements (Vogt et al. 1999, submitted to ApJ). The stellar orbit has a period of about three years, the secondary minimum mass is 6.35 Jupiter masses and the minimum semi-major axis is 0.36 milli-arc-sec (mas). Using the Hipparc

Noam Soker

I propose that the mechanism behind the formation of concentric semi-periodic shells found in several planetary nebulae (PNs) and proto-PNs, and around one asymptotic giant branch (AGB) star, is a solar-like magnetic activity cycle in the progenitor AGB stars. The time intervals between consecutive ejection events is about 200-1,000 years, which is assumed t

M. A. Chaudhry, H. J. Haubold, A. M. Mathai

An analytic study of the reaction probability integrals corresponding to the various forms of the slowly varying cross-section factor $S(E)$ is attempted. Exact expressions for reaction probability integrals are expressed in terms of the extended gamma functions.

H. J. Haubold, A. M. Mathai

The paper discusses the solution of a simple kinetic equation of the type used for the computation of the change of the chemical composition in stars like the Sun. Starting from the standard form of the kinetic equation it is generalized to a fractional kinetic equation and its solutions in terms of H-functions are obtained. The role of thermonuclear functio

M. Contini, S. M. Viegas

This paper aims to understand the continuum of Seyfert 2 galaxies. By fitting the single galaxies in the sample of Heckman et al. (1995) with composite models (shock+ photoionization from the active center), we show that five main components characterize the SED of the continuum. Shocks play an important role since they produce a high temperature zone where

R. A. Swaters, B. F. Madore, M. Trewhella

High resolution Halpha rotation curves are presented for five low surface brightness galaxies. These Halpha rotation curves have shapes different from those previously derived from HI observations, probably because of the higher spatial resolution of the Halpha observations. The Halpha rotation curves rise more steeply in the inner parts than the HI rotation

Dumitru Ghilencea, Graham Ross

We discuss whether the (MSSM) unification of gauge couplings can be accommodated in string theories with a low (TeV) string scale. This requires either power law running of the couplings or logarithmic running extremely far above the string scale. In both cases it is difficult to arrange for the multiplet structure to give the MSSM result. For the case of po

M. Ciafaloni, P. Ciafaloni, D. Comelli

We point out that, since the colliders initial states (e+ e-,p p, p pbar, ... ) carry a definite nonabelian flavor, electroweak radiative corrections to inclusive hard cross sections at the TeV scale are affected by peculiar Bloch-Nordsieck violating double logs. We recall the setup of soft cancellation theorems, and we analyze the magnitude of the noncancel

Gentaro Watanabe, Kei Iida, Katsuhiko Sato

Equilibrium phase diagrams for neutron star matter at subnuclear densities are obtained at zero temperature. Spherical, rod-like and slab-like nuclei as well as spherical and rod-like nuclear bubbles are taken into account by using a compressible liquid-drop model. This model is designed to incorporate uncertainties in the nuclear surface tension and in the

M. M. Sheikh-Jabbari

In this paper we consider D=4 NCSYM theories with 8 supercharges. We study these theories through a proper type IIA (and M-theory) brane configuration. We find the one loop beta function of these theories and show that there is an elliptic curve describing the moduli space of the theory, which is in principle the same as the curve for the commutative counter

Arsen Khvedelidze, George Lavrelashvili, Takahiro Tanaka

The unconstrained reduced action corresponding to the dynamics of scalar fluctuations about the Friedmann-Robertson-Walker (FRW) background is derived using Dirac's method of description of singular Lagrangian systems. The results are applied to so-called negative mode problem in description of tunneling transitions with gravity. With our special choice

Zoltan Haiman

Empirical studies of the first generation of stars and quasars will likely become feasible within the next decade in several different wavelength bands. Microwave anisotropy experiments, such as MAP or Planck, will set constraints on the ionization history of the intergalactic medium due to these sources. In the infrared, the Next Generation Space Telescope

K. Shiokawa

Mesoscopic effects associated with wave propagation in spacetime with metric stochasticity are studied. We show that the scalar and spinor waves in a stochastic spacetime behave similarly to the electrons in a disordered system. Viewing this as the quantum transport problem, mesoscopic fluctuations in such a spacetime are discussed. The conductance and its f

J. Felber, R. Gaehler, R. Golub

Rauch et al (PRL 83, 4955, 1999) have compared their measurements of the Gd cross section for Ultra-cold neutrons with an exptrapolation of the cross section for thermal neutrons and interpreted the discrepancy in terms of coherence properties of the neutron. We show the extrapolation used is based on a misunderstanding and that coherence properties play no

Constantine Yannouleas, Uzi Landman

Second electron affinities of Au_N and Ag_N clusters and the dissociation energies for fission of the Au_N^{2-} and Ag_N^{2-} dianions are calculated using the finite-temperature shell-correction method and allowing for triaxial deformations. Dianionic clusters with N > 2 are found to be energetically stable against fission, leaving electron autodetachment a

Robert D. Cousins

Roe and Woodroofe (RW) have suggested that certain conditional probabilities be incorporated into the ``unified approach'' for constructing confidence intervals, previously described by Feldman and Cousins (FC). RW illustrated this conditioning technique using one of the two prototype problems in the FC paper, that of Poisson processes with backgroun

Giorgio Ottaviani, Raffaella Paoletti

We prove that the Veronese embedding of P^n of degree d with n\ge 2, d\ge 3 does not satisfy property N_p (according to Green and Lazarsfeld) if p\ge 3d-2. We conjecture that the converse holds. This is true for n=2 and for n=d=3.

O. B. Zaslavskii

It is argued that in certain 2d dilaton gravity theories there exist self-consistent solutions of field equations with quantum terms which describe extreme black holes at nonzero temperature. The curvature remains finite on the horizon due to cancelation of thermal divergencies in the stress-energy tensor against divergencies in the classical part of field e

Gene Cooperman, Luis Anchordoqui, Victor Grinberg, Thomas McCauley

We describe a scalable parallelization of Geant4 using commodity hardware in a collaborative effort between the College of Computer Science and the Department of Physics at Northeastern University. The system consists of a Beowulf cluster of 32 Pentium II processors with 128 MBytes of memory each, connected via ATM and fast Ethernet. The bulk of the parallel

Sergey Troshin, Nikolai Tyurin

We consider geometrical properties of the polarized and unpolarized structure functions and provide definition for the $b$--dependent structure functions. It is shown that unitarity does not allow factorized form of the structure functions over the $x$ and $b$ variables. We conclude that the spin of constituent quark has a significant orbital angular momentu

John Womersley

I briefly summarize the prospects for extending our understanding of physics beyond the standard model within the next five years.

Leonid Ya. Kobelev

Physical phenomena caused by particle's moving faster than light in a space with multifractal time with dimension close to integer ($d_{t}=1+ε(r(t),t), |ε| \ll 1$ - time is almost homogeneous and almost isotropic) are considered. The presence of gravitational field is taken into account. According to the results of the developed by the author theory, a p

L. Ya. Kobelev

Relative motion in space with multifractal time (fractional dimension of time close to integer $d_{t}=1+ε(r,t), ε\ll 1$) for "almost" inertial frames of reference (time is almost homogeneous and almost isotropic) is considered. Presence in such space of absolute frames of reference and violation of conservation laws (though, small because of the smal

J. E. Gubernatis, M. Guerrero

We give a brief discussion of the recently developed Constrained-Path Monte Carlo Method. This method is a quantum Monte Carlo technique that eliminates the fermion sign problem plaguing simulations of systems of interacting electrons. The elimination is accomplished by trading an exact procedure for an approximate one that has been demonstrated to give very

D. Pal, D. Dasgupta, B. K. Sarma, S. Bhattacharya

The peak effect (PE) has been observed in a twinned crystal of YBa$_2$Cu$_3$O$_{7-δ}$ for H$\parallel$c in the low field range, close to the zero field superconducting transition temperature (T$_c$(0)) . A sharp depinning transition succeeds the peak temperature T$_p$ of the PE. The PE phenomenon broadens and its internal structure smoothens out as the field

Y. N. Skryabin, A. V. Chukin, A. V. Shchanov

The effects of rare regions on the critical properties of quantum antiferromagnets with hidden degrees of freedom within the renormalization group is discussed. It is shown that for ``constrained'' systems the stability range on the phase diagram remains the same as in the mean-field theory while for ``unconstrained'' systems the stability ra

R. J. Thacker, H. M. P. Couchman

We present a detailed investigation of different approaches to modeling feedback in simulations of galaxy formation. Gas-dynamic forces are evaluated using Smoothed Particle Hydrodynamics (SPH) while star formation and supernova feedback are included using a three parameter model which determines the star formation rate normalization, feedback energy and lif

Ray Jayawardhana, Wayne S. Holland, Jane S. Greaves, William R. F. Dent

The presence of debris disks around $\sim$ 1-Gyr-old main sequence stars suggests that an appreciable amount of dust may persist even in mature planetary systems. Here we report the detection of dust emission from 55 Cancri, a star with one, or possibly two, planetary companions detected through radial velocity measurements. Our observations at 850$μ$m and 4

Nestor Sanchez, Neyda Anez

We calculate the thermochemical equilibrium of the diffuse interstellar medium, including ionization by a photon flux F_{nu} from neutrino decay. The main heating mechanism considered is photoelectrons from grains and PAHs. For the studied range of F_{nu} values, there always exists two regions of stability (a warm and a cold phase) that can coexist in equil

The MACHO collaboration, C. Alcock, R. A. Allsman, D. R. Alves

We report on our search for microlensing towards the Large Magellanic Cloud (LMC). Analysis of 5.7 years of photometry on 11.9 million stars in the LMC reveals 13 - 17 microlensing events. This is significantly more than the $\sim$ 2 to 4 events expected from lensing by known stellar populations. The timescales ($\that$) of the events range from 34 to 230 da

Thomas Matheson, Alexei V. Filippenko, Ryan Chornock, Douglas C. Leonard

We present the first unambiguous detection of helium emission lines in spectra of Type Ic supernovae (SNe Ic). The presence of He I lines, with full width at half maximum ~ 2000 km/s, and the distinct absence of any other intermediate-width emission (e.g., Halpha), implies that the ejecta of SN Ic 1999cq are interacting with dense circumstellar material comp

S. Cheluvaraja, N. D. Hari Dass

The axial anomaly equation in 1+1 dimensional QED is obtained on the lattice for fermions obeying the Ginsparg-Wilson relation. We make use of the properties of the Lattice Dirac sea to investigate the connection between the anomaly and the Ginsparg-Wilson operator in the Hamiltonian picture. The correct anomaly is reproduced for gauge fields whose character

Barry Brent

We give upper bounds on the size of the gap between a non-zero constant term and the next non-zero Fourier coefficient of an entire level two modular form. We give upper bounds for the minimum positive integer represented by a level two even positive-definite quadratic form. These bounds extend partial results in part I.

Madhavan Varadarajan, José A. Zapata

We analyze the classical limit of kinematic loop quantum gravity in which the diffeomorphism and hamiltonian constraints are ignored. We show that there are no quantum states in which the primary variables of the loop approach, namely the SU(2) holonomies along {\em all} possible loops, approximate their classical counterparts. At most a countable number of

Eric Chopin

This paper exposes a reformulation of some gauge theories in terms of explicitly gauge-invariant variables. We show in the case of Scalar QED that the classical theory can be reformulated locally with some gauge invariant variables. We discuss the form of some realistic asymptotic solutions to these equations. The equations of motion are then also reformulat

U. D. Jentschura

A method for the resummation of nonalternating divergent perturbation series is described. The procedure constitutes a generalization of the Borel-Padé method. Of crucial importance is a special integration contour in the complex plane. Nonperturbative imaginary contributions can be inferred from the purely real perturbative coefficients. A connection is dra

R. Arvieu, P. Rozmej, M. Turek

The motion of circular WP for one electron in central Coulomb field with high Z is calculated. The WP is defined in terms of solutions of the Dirac equation in order to take into account all possible relevant effects in particular the spin-orbit potential. A time scale is defined within which spin dynamics must be taken into account mainly in the atoms with

R. Aloisio, P. Blasi, P. L. Ghia, A. F. Grillo

The study of the interactions of Cosmic Rays (CR's) with universal diffuse background radiation can provide very stringent tests of the validity of Special Relativity. The interactions we consider are the ones characterized by well defined energy thresholds whose energy position can be predicted on the basis of Special Relativity. We argue that the exper

Ph. Brune, A. P. Kampf

We apply a diagrammatic expansion method around the atomic limit (U >> t) for the U-t-t' Hubbard model at half filling and finite temperature by means of a continued fraction representation of the one-particle Green's function. From the analysis of the spectral function A(\vec{k},ω) we find an energy dispersion relation with a (cos k_x-cos k_y)^2 mod