June 1998 arXiv papers — page 6

Roberto Fernández, Pablo A. Ferrari, Nancy L. Garcia

We present a probabilistic approach for the study of systems with exclusions, in the regime traditionally studied via cluster-expansion methods. In this paper we focus on its application for the gases of Peierls contours found in the study of the Ising model at low temperatures, but most of the results are general. We realize the equilibrium measure as the i

Klaus Behrndt, Ilka Brunner, Ingo Gaida

We present a detailed analysis of $AdS_3$ gravity, the BTZ black hole and the associated conformal field theories (CFTs). In particular we focus on the non-extreme six-dimensional string solution with background metric $AdS_3 \times S^3$ near the horizon. In addition we introduce momentum modes along the string, corresponding to a BTZ black hole, and a Taub-

Laszlo E. Szabo

Reichenbach's Common Cause Principle claims that if there is correlation between two events and none of them is directly causally influenced by the other, then there must exist a third event that can, as a common cause, account for the correlation. The EPR-Bell paradox consists in the problem that we observe correlations between spatially separated event

F. Dahia

We give a brief discussion on the limitations involving the expression mu ={angular deficit}/(8*pi),(G=c=1), which relates the string linear energy density ''mu'' to the conical deficit angle. Then, we establish a new equation between the angular deficit and another physical attribute of the string which shows that the angular deficit is dete

G. Papadopoulos, A. Teschendorff

We find new solutions of IIA supergravity which have the interpretation of intersecting NS-5-branes at $Sp(2)$-angles on a string preserving at least 3/32 of supersymmetry. We show that the relative position of every pair of NS-5-branes involved in the superposition is determined by four angles. In addition we explore the related configurations in IIB string

Renato Ghisellini

Equilibrium pricing has been proven to underlie the rational Insured expectancy of premia additivity for composition of policies fully covering independent risks.

Guangjun Mao, P. Papazoglou, S. Hofmann, S. Schramm

A new chiral SU(3) Lagrangian is proposed to describe the properties of kaons and antikaons in the nuclear medium, the ground state of dense matter and the kaon-nuclear interactions consistently. The saturation properties of nuclear matter are reproduced as well as the results of the Dirac-Brückner theory. Our numerical results show that the kaon effective m

V. Gimenez, J. Reyes

In this work, we find the expressions of continuum HQET four-fermion operators in terms of lattice operators in perturbation theory. To do so, we calculate the one--loop continuum--lattice HQET matching for the complete basis of $ΔB=2$ and $ΔB=0$ operators (excluding penguin diagrams), extending and completing previous studies. We have also corrected some er

A. Strumia, N. Tetradis

We present a consistent picture of tunnelling in field theory. Our results apply both to high-temperature field theories in four dimensions and to zero-temperature three-dimensional ones. Our approach is based on the notion of a coarse-grained potential U_k that incorporates the effect of fluctuations with characteristic momenta above a given scale k. U_k is

Wen-ge Wang, Bambi Hu

For energy eigenfunctions of 1-dimensional tight binding model, the distribution of ratio of their nearest components, denoted by f(p), gives information for their fluctuation properties. The shape of f(p) is studied numerically for three versions of the 1D tight binding model. It is found that when perturbation is strong the shape of f(p) is usually quite c

J. A. Sellwood, S. A. Balbus

When present, extended disks of neutral hydrogen around spiral galaxies show a remarkably uniform velocity dispersion of approx 6 km/s. Since stellar winds and supernovae are largely absent in such regions, neither the magnitude nor the constancy of this number can be accounted for in the classical picture in which interstellar turbulence is driven by stella

Michio Watanabe, Youiti Ootuka, Kohei M. Itoh, Eugene E. Haller

We report the low temperature carrier transport properties of a series of nominally uncompensated neutron-transmutation doped (NTD) ^{70} Ge:Ga samples very close to the critical concentration N_c for the metal-insulator transition. The concentration of the sample closest to N_c is 1.0004N_c and it is unambiguously shown that the critical conductivity expone

N. J. Cerf, L. K. Grover, C. P. Williams

A quantum algorithm is known that solves an unstructured search problem in a number of iterations of order $\sqrt{d}$, where $d$ is the dimension of the search space, whereas any classical algorithm necessarily scales as $O(d)$. It is shown here that an improved quantum search algorithm can be devised that exploits the structure of a tree search problem by n

L. Knoell, S. Scheel, E. Schmidt, D. -G. Welsch

The recently derived input-output relations for the radiation field at a dispersive and absorbing four-port device [T. Gruner and D.-G. Welsch, Phys. Rev. A 54, 1661 (1996)] are used to derive the unitary transformation that relates the output quantum state to the input quantum state, including radiation and matter and without placing frequency restrictions.

Jie Liu, Bambi Hu, Baowen Li

The geometric phases of the cyclic states of a generalized harmonic oscillator with nonadiabatic time-periodic parameters are discussed in the framework of squeezed state. It is shown that the cyclic and quasicyclic squeezed states correspond to the periodic and quasiperiodic solutions of an effective Hamiltonian defined on an extended phase space, respectiv

Qiong-gui Lin

The Levinson theorem for nonrelativistic quantum mechanics in two spatial dimensions is generalized to Dirac particles moving in a central field. The theorem relates the total number of bound states with angular momentum $j$ ($j=\pm 1/2, \pm 3/2, ... $), $n_j$, to the phase shifts $η_j(\pm E_k)$ of scattering states at zero momentum as follows: $η_j(μ)+η_j(-

Qiong-gui Lin

A two-dimensional analogue of Levinson's theorem for nonrelativistic quantum mechanics is established, which relates the phase shift at threshold(zero momentum) for the $m$th partial wave to the total number of bound states with angular momentum $m\hbar(m=0,1,2,...)$ in an attractive central field.

S. Prvanovic, Z. Maric

The basic concepts of classical mechanics are given in the operator form. The dynamical equation for a hybrid system, consisting of quantum and classical subsystems, is introduced and analyzed in the case of an ideal nonselective measurement. The nondeterministic evolution is found to be the consequence of the superposition of two different deterministic evo

Gerhard Hummer, Niels Grønbech-Jensen, Martin Neumann

Ewald summation and physically equivalent methods such as particle-mesh Ewald, kubic-harmonic expansions, or Lekner sums are commonly used to calculate long-range electrostatic interactions in computer simulations of polar and charged substances. The calculation of pressures in such systems is investigated. We find that the virial and thermodynamic pressures

Eric Baird

Section 7 of Einstein's 1905 electrodynamics paper gives frequency-shift and aberration formulae that together describe an elongated ellipsoidal wavefront. A Lorentz contraction of this ellipsoid solves most (but not all) of the associated relativistic problems.

Chun Wa Wong

Under certain circumstances, a three-body decay width can be approximated by an integral involving a product of two off-shell two-body decay widths. This ``angle-average'' approximation is used to calculate the $πNN$ decay width of the $d^*(J^π=3^+, T=0)$ dibaryon in a simple $Δ^2$ model for the most important Feynman diagrams describing pion emissio

Silas R. Beane

I review recent progress in developing a systematic power counting scheme for scattering processes involving more than one nucleon.

P. Schuck, Z. Aouissat, F. Bonutti, G. Chanfray

The present status of the in-medium invariant $π-π$ mass distribution in the sigma-meson channel around the threshold is reviewed from the theory side and contrasted with recent experiments on $(π,2π)$ knock-out reactions. A preliminary investigation indicates that the strongly target-mass dependent invariant mass enhancement of the two pions can be explaine

Rahul Pandharipande

This article accompanies my June 1998 seminaire Bourbaki talk on Givental's work. After a quick review of descendent integrals in Gromov-Witten theory, I discuss Givental's formalism relating hypergeometric series to solutions of quantum differential equations arising from hypersurfaces in projective space. A particular case of this relationship is a

Xavier Bressaud, Roberto Fernández, Antonio Galves

We present an upper bound on the mixing rate of the equilibrium state of a dynamical systems defined by the one-sided shift and a non Hölder potential of summable variations. The bound follows from an estimation of the relaxation speed of chains with complete connections with summable decay, which is obtained via a explicit coupling between pairs of chains w

Florian Nill, Kornel Szlachanyi, Hans-Werner Wiesbrock

We apply the theory of finite dimensional weak C^*-Hopf algebras A as developed by G. Böhm, F. Nill and K. Szlachányi to study reducible inclusion triples of von-Neumann algebras N \subset M \subset (M\cros\A). Here M is an A-module algebra, N is the fixed point algebra and \M\cros\A is the crossed product extension. ``Weak'' means that the coproduct

Gabor Elek, Gabor Tardos

The existence of nonconstant harmonic Dirichlet functions on a Cayley graph of a discrete group is equivalent to the nonvanishing of the first L2-cohomology of the given group. It was first proven by Cheeger and Gromov that such functions do not exists on the Cayley-graph of an amenable group. The result was extended using Foster's averaging formula to t

Gabor Elek

The notion of topological entropy is originally defined for a single action. Later it was extended by Kieffer for arbitrary discrete amenable groups. Recently Friedland defined topological entropy for any discrete group actions amenable or not. Lind, Schmidt and Ward extended Yuzvinskii's addition formula from single action to abelian group actions. A re

Meeyoung Kim, Laurent Manivel

We study nonsingular branched coverings of a homogeneous space X. There is a vector bundle associated with such a covering which was conjectured by O. Debarre to be ample when the Picard number of X is one. We prove this conjecture, which implies Barth-Lefschetz type theorems, for lagrangian grassmannians, and for quadrics up to dimension six. We propose a c

Jordan J. Epitropov, Todor Zh. Mollov, Nako A. Nachev

For a field $K$ of the second kind with respect to 2 and of characteristic different from 2, we consider the decomposition of the binomials $x^{2^n} - a$ into a product of irreducible factors over $K$ and find the explicit form of the minimal idempotents of the twisted group algebra $K^t< g>$ of a cyclic 2-group $<g>$ over $K$.

Todor Zh. Mollov, Nako A. Nachev

For a field $K$ of characteristic different from 2, we find the explicit form of the minimal idempotents of the twisted group algebra $K_t< g>$ of a cyclic 2-group $<g>$ over $K$.

Mathijs S. Dijkhuizen, Jasper V. Stokman

The quantum complex Grassmannian U_q/K_q of rank l is the quotient of the quantum unitary group U_q=U_q(n) by the quantum subgroup K_q=U_q(n-l)xU_q(l). We show that (U_q,K_q) is a quantum Gelfand pair and we express the zonal spherical functions, i.e. K_q-biinvariant matrix coefficients of finite- dimensional irreducible representations of U_q, as multivaria

Sungbok Hong, Darryl McCullough

A limit point p of a discrete group of Mobius transformations acting on S^n is called a concentration point if for any sufficiently small connected open neighborhood U of p, the set of translates of U contains a local basis for the topology of S^n at p. For the case of Fuchsian groups (n = 1), every concentration point is a conical limit point, but even for

Neal J. Fowler, Iain Raeburn

Suppose a C*-algebra A acts by adjointable operators on a Hilbert A-module X. Pimsner constructed a C*-algebra O_X which includes, for particular choices of X, crossed products of A by Z, the Cuntz algebras O_n, and the Cuntz-Krieger algebras O_B. Here we analyse the representations of the corresponding Toeplitz algebra. One consequence is a uniqueness theor

M. E. Bowers, C. R. Hagen

The Casimir energy for a conducting spherical shell of radius $a$ is computed using a direct mode summation approach. An essential ingredient is the implementation of a recently proposed method based on Cauchy&#39;s theorem for an evaluation of the eigenfrequencies of the system. It is shown, however, that this earlier calculation uses an improper set of mod

Dieter Mayer, Alexander Ushveridze, Zbigniew Walczak

In this paper we demonstrate that there exists a close relationship between quasi-exactly solvable quantum models and two special classes of classical dynamical systems. One of these systems can be considered a natural generalization of the multi-particle Calogero-Moser model and the second one is a classical matrix model.

A. Bassetto, R. Begliuomini, G. Nardelli

A rectangular Wilson loop centered at the origin, with sides parallel to space and time directions and length $2L$ and $2T$ respectively, is perturbatively evaluated ${\cal O}(g^4)$ in Feynman gauge for Yang--Mills theory in $1+(D-1)$ dimensions. When $D>2$, there is a dependence on the dimensionless ratio $L/T$, besides the area. In the limit $T \to \infty$

Alexios P. Polychronakos

We construct generalizations of the Calogero-Sutherland-Moser system by appropriately reducing a model involving many unitary matrices. The resulting systems consist of particles on the circle with internal degrees of freedom, coupled through modifications of the inverse-square potential. The coupling involves SU(M) non-invariant (anti)ferromagnetic interact

Pedro J. Silva

We report a sign that M(atrix) theory conjecture and the Maldacena conjecture for the case of D0-branes are compatible. Furthermore Maldacena point of view implies a restriction of range of validity in the DLCQ version of M(atrix) theory. The analysis is based on the uplift of type IIA supersymetric solution in the Maldacena approach to eleven dimensions, us

S. Khlebnikov

This paper has been withdrawn by the author as the conjecture proposed in it is wrong.

Alec Matusis

We compute the vacuum one loop amplitude for two D-strings at an angle compactified on $T^2$ as a function of the transverse separation and the winding numbers. We show that in certain cases the amplitude is independent on whether the D-strings are compactified or not.

U. K. Yang, A. Bodek

We extract the ratio of the down (d) and up (u) parton distribution functions (PDF&#39;s) from the ratio of deuteron and proton structure function F_2(d)/F_2(p) measured by NMC. We use corrections for nuclear binding effects in the deuteron, which are extracted from the nuclear dependence of SLAC F_2 data. Significant corrections to the d quark distribution

M. Bertini, M. Genovese, N. N. Nikolaev, B. G. Zakharov

We present the QCD calculation of the diffractive structure function for charged current DIS. In particular we analyse the perturbatively tractable excitation of heavy quarks. We emphasize the peculiarities of the Regge factorization breaking in excitation of open charm.

Fabio Maltoni, Andrea Petrelli

We investigate the effects of colour-octet contributions to the radiative $Υ$ decay within the Bodwin, Braaten and Lepage NRQCD factorization framework. Photons coming both from the coupling to hard processes (`direct&#39;) and by collinear emission from light quarks (`fragmentation&#39;) are consistently included at next-to-leading order (NLO) in $α_s$. An

Ning Wu

In this paper, applying general gauge field theory, we will construct an electroweak model. In this new electroweak model, Higgs mechanism is not used, so no Higgs particle exists in the model. In order to keep the masses of intermediate gauge bosons non-zero, we will introduce two sets of gauge fields. We need a vacuum potential to introduce symmetry breaki

F. del Aguila, A. Culatti, R. Munoz-Tapia, M. Perez-Victoria

We describe in detail the constrained procedure of differential renormalization and develop the techniques required for one-loop calculations. As an illustration we renormalize Scalar QED and show that the two-, three- and four-point Ward identities are automatically satisfied.

F. Benatti, R. Floreanini

It has been recently proposed to study generic dynamical evolutions of the neutral kaon system that go beyond quantum mechanics. We explicitly show that, unless the condition of complete positivity is enforced, those dynamics are physically inconsistent and should be rejected.

S. P. Baranov, N. P. Zotov

In the framework of semihard QCD approach, with the emphasis on the BFKL evolution of gluon distributions, we calculate the differential cross sections of inclusive $D^{*\pm}$ mesons electroproduction at HERA and confront our results with available ZEUS experimental data.

Junegone Chay

The nonperturbative contribution, suppressed by powers of the charm quark mass m_c, in the inclusive decay B -> X_s photon is analyzed in the context of heavy quark effective field theory (HQEFT). According to previous analyses, the leading effects of O(1/m_c^2) arise from an external gluon attached to a charm quark loop and can be expressed in terms of the

C. -H. Lee, H. Yamagishi, I. Zahed

We analyze the $γγ\to ππ, KK, ηη, πη$ reactions through $\sqrt{s}=2$ GeV, using the master formula approach to QCD with three flavors. In this approach, the constraints of broken chiral symmetry, unitarity and crossing symmetry are manifest in all channels. The pertinent vacuum correlators are analyzed at tree level using straightforward resonance saturation

C. Boros

Recent measurement of the structure function $F_2^ν$ in neutrino deep inelastic scattering allows us to compare structure function measured in neutrino and charged lepton scattering for the first time with reasonable precision. The comparison between neutrino and muon structure functions made by the CCFR Collaboration indicates that there is a discrepancy be

Michael Grady

A gauge invariant procedure for extracting combined SO(3)-Z2 monopoles in positive-plaquette SU(2) lattice gauge theory is shown. When these monopoles are eliminated through a constraint, the theory deconfines for all $β$ on $12^4$ and $20^4$ lattices even in the strong coupling limit, despite a rather strong average plaquette of around 0.64. This correspond

Tommaso Dorigo

A search for Z boson decays to pairs of b-quark jets has been performed in the full dataset collected with the CDF detector at the Tevatron proton-antiproton collider. After the selection of a pure sample of bb events by means of the identification of secondary vertices from b-quark decays, we have used two kinematic variables to further discriminate the ele

Yasunori Fujii

We revisit the proposed theoretical model for a small but nonzero cosmological constant which seems supported increasingly better by recent observations. The model features two scalar fields which interact with each other through a specifically chosen nonlinear potential. We find a very sensitive dependence of the solutions of the scalar field equations on t

Edward Seidel

I review recent developments in numerical relativity, focussing on progress made in 3D black hole evolution. Progress in development of black hole initial data, apparent horizon boundary conditions, adaptive mesh refinement, and characteristic evolution is highlighted, as well as full 3D simulations of colliding and distorted black holes. For true 3D distort

Edward Seidel

I describe approaches to the study of black hole spacetimes via numerical relativity. After a brief review of the basic formalisms and techniques used in numerical black hole simulations, I discuss a series of calculations from axisymmetry to full 3D that can be seen as stepping stones to simulations of the full 3D coalescence of two black holes. In particul

Judith Mueller, Martin Grant

We propose a model based on a Ginzburg-Landau approach to study a strain relief mechanism at a free interface of a non-hydrostatically stressed solid, commonly observed in thin-film growth. The evolving instability, known as the Grinfeld instability, is studied numerically in two and three dimensions. Inherent in the description is the proper treatment of no

J. Stockburger, C. H. Mak

Dynamical localization of a tunneling system by means of an oscillating external field is examined for an arbitrary doublet of tunneling states. We show that the condition of an exact crossing of Floquet levels, required for localization in a symmetric system, can be substantially relaxed for tunneling systems with broken symmetry. This generalization equall

J. K. Freericks, V. Zlatic&#39;, Woonki Chung, Mark Jarrell

A series of weak-coupling perturbation theories which include the lowest-order vertex corrections are applied to the attractive Holstein model in infinite dimensions. The approximations are chosen to reproduce the iterated perturbation theory in the limit of half-filling and large phonon frequency (where the Holstein model maps onto the Hubbard model). Compa

R. W. Nunes, J. Bennetto, David Vanderbilt

We investigate the energetics of the single-period and double-period core reconstructions of the 90-degree partial dislocation in the homopolar semiconductors C, Si, and Ge. The double-period geometry is found to be lower in energy in all three materials, and the energy difference between the two geometries is shown to follow the same trends as the energy ga

L. Bellaiche, David Vanderbilt

We present a simple ionic model which successfully reproduces the various types of compositional long-range order observed in a large class of complex insulating perovskite alloys. The model assumes that the driving mechanism responsible for the ordering is simply the electrostatic interaction between the different ionic species. A possible new explanation f

M. Hennion, F. Moussa, G. Biotteau, J. Rodriguez-Carvajal

Elastic neutron scattering experiments performed in semi-conducting La(1-x)Ca(x)MnO3 single crystals (x=0.05, 0.08), reveal new features in the problem of electronic phase separation and metal insulator transition. Below TN, the observation of a broad magnetic modulation in the q-dependent scattering intensity, centered at nearly identical qm whatever the q

K. Park, V. Melik-Alaverdian, N. E. Bonesteel, J. K. Jain

We find that for the pure Coulomb repulsion the composite Fermi sea at $ν=1/2$ is on the verge of an instability to triplet pairing of composite fermions. It is argued that a transition into the paired state, described by a Pfaffian wave function, may be induced if the short-range part of the interaction is softened by increasing the thickness of the two-dim

J. -B. Fournier

A continuum Landau theory for the micro-elasticity of membranes is discussed, which incorporates a coupling between the bilayer thickness variation and the difference in the two monolayers&#39; tilts. This coupling stabilizes a new phase with a rippled micro-structure. Interactions among membrane inclusions combine a dilation-induced attraction and a tilt-di

J. B. Kycia, J. I. Hong, M. J. Graf, J. A. Sauls

High quality single crystals of UPt_3 have been prepared by vertical float-zone refining in ultra-high vacuum. We find that the superconducting transition temperature can be varied systematically by annealing, revealing that the transition temperature intrinsic to UPt_3 is 563 +/- 5 mK. The suppression of the superconducting transition from defects is consis

Xavier Farreres, German Rigau, Horacio Rodriguez

This paper summarises a set of methodologies and techniques for the fast construction of multilingual WordNets. The English WordNet is used in this approach as a backbone for Catalan and Spanish WordNets and as a lexical knowledge resource for several subtasks.

German Rigau, Horacio Rodriguez, Eneko Agirre

This paper presents a method that combines a set of unsupervised algorithms in order to accurately build large taxonomies from any machine-readable dictionary (MRD). Our aim is to profit from conventional MRDs, with no explicit semantic coding. We propose a system that 1) performs fully automatic exraction of taxonomic links from MRD entries and 2) ranks the

Bai-lin Hao

Symbolic dynamics is a coarse-grained description of dynamics. By taking into account the ``geometry&#39;&#39; of the dynamics, it can be cast into a powerful tool for practitioners in nonlinear science. Detailed symbolic dynamics can be developed not only for one-dimensional mappings, unimodal as well as those with multiple critical points and discontinuiti

L. Benet, C. Jung, T. Papenbrock, T. H. Seligman

After early work of Henon it has become folk knowledge that symmetric periodic orbits are of particular importance. We reinforce this belief by additional studies and we further find that invariant closed symplectic submanifolds caused by discrete symmetries prove to be an important complement to the long known role of the orbits. The latter have particular

J. Bland-Hawthorn

We discuss the sources which are likely to dominate the ionizing field throughout the Local Group. In terms of the limiting flux to produce detectable H-alpha emission (4-10 x 10**3 phot/cm**2/s), the four dominant galaxies (M31, Galaxy, M33, LMC) have spheres of influence which occupy a small fraction (<10%) of the Local Volume. There are at least two possi

M. A. Pahre, S. G. Djorgovski, R. R. de Carvalho

Near-infrared imaging data on 251 early-type galaxies in clusters and groups are used to construct the near-infrared Fundamental Plane (FP) r_eff ~ sigma_0^1.53 <Sigma_K>_eff^-0.79. The slope of the FP therefore departs from the virial expectation of r_eff ~ sigma_0^2 <Sigma>_eff^-1 at all optical and near-infrared wavelengths, which could be a result of the

Laura Silva, Gian Luigi Granato, Alessandro Bressan, Luigi Danese

We present models of photometric evolution of galaxies in which the effects of a dusty interstellar medium have been included with particular care. A chemical evolution code follows the star formation rate, the gas fraction and the metallicity, basic ingredients for the stellar population synthesis. The latter is performed with a grid of integrated spectra o

Javier Gorosabel, Alberto Castro-Tirado

We present here the results of a study carried out at the Harvard College Observatory Plate Collection. We examined 3995 plates covering the error box of the gamma-ray burst GRB 910122, over a time span of 90 yr (from 1889 to 1979). The total exposure time is ~0.55 yr. No convincing evidence of optical transient emission was found within the GRB 910122 IPN e

Amr El-Zant

The evolution of closed gravitational systems is studied by means of $N$-body simulations. This, as well as being interesting in its own right, provides insight into the dynamical and statistical mechanical properties of gravitational systems: the possibility of the existence of stable equilibrium states and the associated relaxation time would provide an id

T. Bloecker, H. Holweger, B. Freytag, F. Herwig

Based on radiation hydrodynamics modeling of stellar convection zones, a diffusion scheme has been devised describing the downward penetration of convective motions beyond the Schwarzschild boundary (overshoot) into the radiative interior. This scheme of exponential diffusive overshoot has already been successfully applied to AGB stars. Here we present an ap

Luis Masperi, Milva Orsaria

We evaluate the matter-antimatter asymmetry produced by emission of fermionic carriers from vortons which are assumed to be destabilized at the electroweak phase transition.The velocity of contraction of the vorton, calculated through the decrease of its magnetic energy, originates a chemical potential which allows a baryogenesis of the order of the observed

Sarbani Basu, H. M. Antia, S. C. Tripathy

Ring diagram analysis of solar oscillation power spectra obtained from MDI data is performed to study the velocity fields within the solar convection zone. The three dimensional power spectra are fitted to a model with a Lorentzian profile in frequency and includes the advection of the wave front by horizontal flows to obtain the two horizontal components of

Mareki Honma, Yukitoshi Kan-ya

If the Galactic rotation speed at the Solar circle is $\sim 200$ km s$^{-1}$ or smaller, which is supported by several recent studies, the rotation curve of the Galaxy could be declining in the outermost region. Motivated by this, we investigate the effect of such declining rotation curve on the estimate of the MACHO mass and the fractional contribution of t

Z. G. Dai, T. Lu

The afterglow of a gamma-ray burst (GRB) is commonly thought to be due to continuous deceleration of a relativistically expanding fireball in the surrounding medium. Assuming that the expansion of the fireball is adiabatic and that the density of the medium is a power-law function of shock radius, viz., $n_{ext}\propto R^{-k}$, we analytically study the effe

Gerhardt R. Meurer

Optical and HI imaging of gas rich dwarfs, both dwarf irregulars (dI) and blue compact dwarfs (BCD), reveals important clues on how dwarf galaxies evolve and their star formation is regulated. Both types usually show evidence for stellar and gaseous disks. However, their total mass is dominated by dark matter. Gas rich dwarfs form with a range of disk struct

Paul Hickson, E. Harvey Richardson

Images obtained by drift-scanning with a stationary telescope are affected by the declination-dependent curvature of star trails. The image displacement to curvature and drift rate variation increases with the angular field of view and can lead to significant loss of resolution with modern large-format CCD arrays. We show that these effects can be essentiall

Gerardo O. Depaola, Carlos N. Kozameh, Manuel H. Tiglio

A method to determine the polarization direction of a very high energy (50 MeV - 30 GeV), linearly polarized gamma ray is analyzed and discussed. We study the differential cross section for pair production and show that the only relevant piece of information comes from the reconstruction of the pair trajectory. In particular the polarization information is c

B. K. Jennings, S. Karataglidis, T. D. Shoppa

We investigate the energy dependence of the astrophysical $S$ factor for the reaction $^7$Be$(p,γ)^8$B, the primary source of high-energy solar neutrinos in the solar $pp$ chain. Using simple models we explore the model dependence in the extrapolation of the experimental data to the region of astrophysical interest near 20 keV. We find that below approximate

Lewis P. Fulcher

We present a comprehensive calculation of the energies, splittings and electromagnetic decay rates of the bottom charmed meson system. Our calculated result for the ground state lifetime is 0.38 \pm 0.03 ps, in good agreement with the recent CDF measurement. In order to incorporate running coupling constant effects, we choose Richardson&#39;s potential for t

G. Esirgen, H. -B. Schüttler, N. E. Bickers

The one-band extended Hubbard model in two dimensions near band-filling 1/2 is solved in the fluctuation exchange approximation, including the long-range (1/r) part of the Coulomb interaction, up to 4th neighbor distance. Our results suggest that d_(x^2 - y^2) pairing in the Hubbard model is robust against the inclusion of long-range Coulomb interactions wit

M. R. Norman, H. Ding, H. Fretwell, M. Randeria

The self-energy $Σ({\bf k},ω)$, the fundamental function which describes the effects of many-body interactions on an electron in a solid, is usually difficult to obtain directly from experimental data. In this paper, we show that by making certain reasonable assumptions, the self-energy can be directly determined from angle resolved photoemission data. We de

M. A. Gomez, L. R. Pratt

This paper investigates Monte Carlo techniques for construction of compact wavefunctions for the internal atomic motion of the D3O+ ion. The polarization force field models of Stillinger, et al and of Ojamae, et al. were used. Initial pair product wavefunctions were obtained from the asymptotic high temperature many-body density matrix after contraction to a

S. F. King

We follow a minimalistic approach to neutrino masses, by introducing a single heavy singlet $N$ into the standard model (or supersymmetric standard model) with a heavy Majorana mass $M$, which couples as a single right-handed neutrino in a Dirac fashion to leptons, and induces a single light see-saw mass $m_ν\sim 5\times 10^{-2} eV$, leaving two neutrinos ma

Alexander Vilenkin

``Constants of Nature&#39;&#39; and cosmological parameters may in fact be variables related to some slowly-varying fields. In models of eternal inflation, such fields will take different values in different parts of the universe. Here I show how one can assign probabilities to values of the ``constants&#39;&#39; measured by a typical observer. This method d

B. Ermolaev, R. Kirschner, L. Szymanowski

We study the small-$x$ behaviour of the polarized photon structure function $F_3^{\ga}$, measuring the gluon transversity distribution, in the leading logarithmic approximation of perturbative QCD. There are two contributions, both arising from two-gluon exchange. The leading contribution to small-$x$ is related to the BFKL pomeron and behaves like $x^{-1-\o

A. Marrone, A. D. Polosa, G. Scioscia, S. Stramaglia

We describe the multiresolution wavelet analysis of blood pressure waves in vasovagal syncope affected patients compared with healthy people. We argue that there exist discriminating criteria which allow us to isolate particular features, common to the syncope-affected patients sample, indicating an alternative diagnosis methodology for this syndrome. We per

G. Mussardo

The lowest representatives of the Form Factors relative to the trace operators of N=1 Super Sinh-Gordon Model are exactly calculated. The novelty of their determination consists in solving a coupled set of unitarity and crossing equations. Analytic continuations of the Form Factors as functions of the coupling constant allows the study of interesting models

Sergio Gelato, Jesper Sommer-Larsen

We investigate the claim by Burkert and Silk (1997) that the observed rotation curve of the dwarf irregular galaxy DDO154 cannot be reconciled with the universal CDM halo profile of Navarro, Frenk & White (1996,1997) even when allowance is made for the effect of violent gas outflow events on the structure of the galaxy. By means of N-body simulations we show

Niranjan Ramachandran

We introduce new motivic invariants of arbitrary varieties over a perfect field. These cohomological invariants take values in the category of one-motives (considered up to isogeny in positive characteristic). The algebraic definition of these invariants presented here proves a conjecture of Deligne. Applications include some cases of conjectures of Serre, K

I. T. Habibullin

Initial boundary value problem on a half-line for the Modified KdV equation is considered with the boundary conditions equal to zero at the origin and initial condition chosen arbitrary decreasing rapidly enough and this problem is plunged into the scheme of the inverse scattering method. Here the inverse scattering problem is reduced to the Riemann problem

C. W. J. Beenakker

We compute the statistics of thermal emission from systems in which the radiation is scattered chaotically, by relating the photocount distribution to the scattering matrix - whose statistical properties are known from random-matrix theory. We find that the super-Poissonian noise is that of a black body with a reduced number of degrees of freedom. The genera

Zhen Wang

A generalized framework is developed which uses a set description instead of wavefunction to emphasize the role of the observer. Such a framework is found to be very effective in the study of the measurement problem and time&#39;s arrow. Measurement in classical and quantum theory is given a unified treatment. With the introduction of the concept of uncertai

Paul B. Slater

We apply and extend recent results of Krattenthaler and Slater (quant-ph/9612043), who sought quantum analogs of seminal work on universal data compression of Clarke and Barron. KS obtained explicit formulas for the eigenvalues and eigenvectors of the 2^m x 2^m density matrices gotten by averaging the m-fold tensor products with themselves of the 2 x 2 densi

D. Yesilleten, T. A. Arias

The multigrid algorithm is a multilevel approach to accelerate the numerical solution of discretized differential equations in physical problems involving long-range interactions. Multiresolution analysis of wavelet theory provides an efficient representation of functions which exhibit localized bursts of short length-scale behavior. Applications such as com

W. E. Hagston, H. Ketterl

In the past many papers have appeared which simulated surface growth with different growth models. The results showed that, if models differed only slightly in their `growth&#39; rules, the resulting surfaces may belong to different universality classes, i.e. they are described by different differential equations. In the present paper we describe a mapping o