October 1997 arXiv papers — page 11

E. Cremmer, B. Julia, H. Lu, C. N. Pope

We analyse the global (rigid) symmetries that are realised on the bosonic fields of the various supergravity actions obtained from eleven-dimensional supergravity by toroidal compactification followed by the dualisation of some subset of fields. In particular, we show how the global symmetries of the action can be affected by the choice of this subset. This

J. M. Flynn, C. T. Sachrajda

We review the application of lattice QCD to the phenomenology of b- and c-quarks. After a short discussion of the lattice techniques used to evaluate hadronic matrix elements and the corresponding systematic uncertainties, we summarise results for leptonic decay constants, B--Bbar mixing, semileptonic and rare radiative decays. A discussion of the determinat

Priyamvada Natarajan, Steinn Sigurdsson, Joseph Silk

We propose a scenario for the formation of a population of baryon-rich, dark matter-deficient dwarf galaxies at high redshift that form from the mass swept out in the Intergalactic Medium (IGM) by energetic outflows from luminous quasars. We predict the intrinsic properties of these galaxies, and examine the prospects for their observational detection in the

Y. Ashkenazy, C. Goren, L. P. Horwitz

A manifestly relativistically covariant form of the van der Pol oscillator in 1+1 dimensions is studied. We show that the driven relativistic equations, for which $x$ and $t$ are coupled, relax very quickly to a pair of identical decoupled equations, due to a rapid vanishing of the ``angular momentum'' (the boost in 1+1 dimensions). A similar effect

S. M. Alamoudi, D. Boyanovsky, F. I. Takakura

We study the non-equilibrium dynamics of domain walls in real time for $ϕ^4$ and Sine Gordon models in 1+1 dimensions in the dilute regime. The equation of motion for the collective coordinate is obtained by integrating out the meson excitations around the domain wall to one-loop order. The real-time non-equilibrium relaxation is studied analytically and num

Anthony J. Bracken, Xiang-Yu Ge, Yao-Zhong Zhang, Huan-Qiang Zhou

A general graded reflection equation algebra is proposed and the corresponding boundary quantum inverse scattering method is formulated. The formalism is applicable to all boundary lattice systems where an invertible R-matrix exists. As an application, the integrable open-boundary conditions for the $q$-deformed supersymmetric $U$ model of strongly correlate

B. T. Draine, A. Lazarian

Spinning interstellar dust grains produce detectable rotational emission in the 10-100 GHz frequency range. We calculate the emission spectrum, and show that this emission can account for the ``anomalous'' Galactic background component which correlates with 100um thermal emission from dust. Implications for cosmic background studies are discussed.

Philip Maymin

Classical programming languages cannot model essential elements of complex systems such as true random number generation. This paper develops a formal programming language called the lambda-q calculus that addresses the fundamental properties of complex systems. This formal language allows the expression of quantumized algorithms, which are extensions of ran

M. Schwamb, H. Arenhoevel, P. Wilhelm, Th. Wilbois

Photodisintegration of the deuteron above pi-threshold is studied in a coupled channel approach including N-Delta- and pi-d-channels with pion retardation in potentials and exchange currents.

H. Arenhoevel, G. Kress, R. Schmidt, P. Wilhelm

The Gerasimov-Drell-Hearn sum rule is evaluated for the deuteron by explicit integration up to 550 MeV including contributions from the photodisintegration channel and from coherent and incoherent single pion production as well. The photodisintegration channel converges fast enough in this energy range and gives a large negative contribution, essentially fro

Eduardo Bauer, Antonio M. Lallena

The role played by the effective residual interaction in the transverse nuclear response for quasi-free electron scattering is discussed. The analysis is done by comparing different calculations performed in the Random--Phase Approximation and Ring Approximation frameworks. The importance of the exchange terms in this energy region is investigated and the ch

Patrick Speissegger

Every o-minimal expansion R-tilde of the real field has an o-minimal expansion P(R-tilde) in which the solutions to Pfaffian equations with definable C^1 coefficients are definable.

Aapo Halko, Saharon Shelah

This paper answers three questions posed by the first author. In Theorem 2.6 we show that the family of strong measure zero subsets of {}^{omega_1}2 is 2^{aleph_1}-additive under GMA and CH. In Theorem 3.1 we prove that the generalized Borel conjecture is false in {}^{omega_1}2 assuming ZFC+CH. Next, in Theorem 4.2, we show that the family of subsets of {}^{

Jörg Brendle, Saharon Shelah

For a free ultrafilter U on omega we study several cardinal characteristics which describe part of the combinatorial structure of U. We provide various consistency results; e.g. we show how to force simultaneously many characters and many pi --characters. We also investigate two ideals on the Baire space omega^omega naturally related to U and calculate cardi

Saharon Shelah, Lee Stanley

We present a forcing for blowing up 2^lambda and making ``many positive polarized partition relations'' (in a sense made precise in (c) of our main theorem) hold in the interval [lambda, 2^lambda]. This generalizes results of [276], Section 1, and the forcing is a ``many cardinals'' version of the forcing there.

Mirna Džamonja, Saharon Shelah

Various versions of club are shown to be different. A question of Soukup, Fuchino and Juhasz, is it consistent to have a stick without club, is answered as a consequence. The more detailed version of the paper, which is coming up, also answers a question of Galvin.

Jan Kiwi

The aim of this work is to describe the equivalence relations in $\Q/\Z$ that arise as the rational lamination of polynomials with all cycles repelling. We also describe where in parameter space one can find a polynomial with all cycles repelling and a given rational lamination. At the same time we derive some consequences that this study has regarding the t

Marco Martens, Welington de Melo

It will be shown that the smooth conjugacy class of an $S-$unimodal map which does not have a periodic attractor neither a Cantor attractor is determined by the multipliers of the periodic orbits. This generalizes a result by M.Shub and D.Sullivan for smooth expanding maps of the circle.

Joerg Wenzel

A Banach space X is superreflexive if each Banach space Y that is finitely representable in X is reflexive. Superreflexivity is known to be equivalent to J-convexity and to the non-existence of uniformly bounded factorizations of the summation operators S_n through X. We give a quantitative formulation of this equivalence. This can in particular be used to f

Joerg Wenzel

We show that the main problem left open in Wenzel: "Real and complex operator ideals" (wenzelopidls.latex), can be solved using the Banach spaces $Z_α$ recently constructed by Kalton: "An elementary example of a Banach space not isomorphic to its complex conjugate" (kaltoncmplxbsp.tex). This gives an example of a complex operator ideal that h

Joerg Wenzel

We prove the asymptotic equivalence of three sequences of ideal norms associated with the UMD-property of Banach spaces.

John M. Cornwall

Recently several workers have attempted determinations of the so-called magnetic mass of d=3 non-Abelian gauge theories through a one-loop gap equation, using a free massive propagator as input. Self-consistency is attained only on-shell, because the usual Feynman-graph construction is gauge-dependent off-shell. We examine two previous studies of the pinch t

G. Dall'Agata, K. Lechner, M. Tonin

We show that the recently found covariant formulation for chiral $p$--forms in $2(p+1)$ dimensions with $p$ even, can be naturally extended to supersymmetric theories. We present the general method for writing covariant actions for chiral bosons and construct, in particular, in six dimensions covariant actions for one tensor supermultiplet, for pure supergra

M. Henningson

We first consider M-theory formulated on an open eleven-dimensional spin-manifold. There is then a potential anomaly under gauge transformations on the E_8 bundle that is defined over the boundary and also under diffeomorphisms of the boundary. We then consider M-theory configurations that include a five-brane. In this case, diffeomorphisms of the eleven-man

Myck Schwetz, Maxim Zabzine

We study the sypersymmetric pure Yang-Mills theory with semisimple Lie groups. We show that the general form of the gluino condensate is determined solely by the symmetries of the theory and it is in disagreement with the recently proposed existence of a conformal phase in SYM theory. We discuss the peculiarities of the Veneziano-Yankielowicz effective Lagra

A. V. Smilga, A. I. Veselov

Solving numerically the equations of motion for the effective lagrangian describing supersymmetric QCD with the SU(2) gauge group, we find a menagerie of complex domain wall solutions connecting different chirally asymmetric vacua. Some of these solutions are BPS saturated walls; they exist when the mass of the matter fields does not exceed some critical val

Emil Martinec

N=2 heterotic strings may provide a window into the physics of M-theory radically different than that found via the other supersymmetric string theories. In addition to their supersymmetric structure, these strings carry a four-dimensional self-dual structure, and appear to be completely integrable systems with a stringy density of states. These lectures giv

M. M. Sheikh-Jabbari

In this paper, we consider two D-branes rotated with respect to each other, and argue that in this way one can find brane configurations preserving ${1 \f 16}$ of SUSY. Also we classify different brane configurations preserving ${1 \f 2}$, ${1 \f 4}$, ${3 \f 16}$,${1 \f 8}$, ${1 \f 16}$ of SUSY.

L. Bonora, A. Sorin

We propose a new integrable N=2 supersymmetric Toda lattice hierarchy which may be relevant for constructing a supersymmetric one-matrix model. We define its first two Hamiltonian structures, the recursion operator and Lax--pair representation. We provide partial evidence for the existence of an infinite-dimensional N=2 superalgebra of its flows. We study it

Jani Lukkarinen

We prove that the simple condition on the potential V, \int exp(-t V) < \infty for all t>0, is sufficient for the lattice approximation of the trace Tr[A exp(-b H)] with (Re b)>0 to work for all bounded functions A and a large class of potentials. As a by-product we obtain an explicit bound for the real-temperature lattice kernels.

Robert D. Pisarski

I give a pedagogical review of the derivation for the effective lagrangian for nonabelian Debye screening, or hard thermal loops. Following Kelly, Liu, Lucchesi, and Manuel, I give the simplest derivation possible, using classical kinetic theory. The result is valid not just for a thermal, but for an arbitrary initial distributions. I use this to study the e

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

Howard Baer, James D. Wells

Determining the origin of electroweak symmetry breaking will be one of the primary functions of high energy colliders. We point out that most Higgs boson searches pursued at hadron colliders require Yukawa interactions either in the production or the decay of a Higgs boson. We propose a trilepton Higgs boson search based only upon the gauge interactions of t

A. De Roeck, R. Engel, A. Rostovtsev

In this article we discuss the possibility to measure diffraction dissociation in collisions of real and weakly virtual photons at a 500 GeV e+e- linear collider.

Stefan Groote

In this talk I consider QCD sum rules for the ground state heavy baryons to leading order in $1/m_Q$ and at next-to-leading order in $α_S$ within the context of Heavy Quark Symmetry. The analysis is done at a fixed scale $μ=1 GeV$. The evolution behaviour of the residues is determined by the two-loop anomalous dimension of the heavy baryon currents calculate

J. F. Bennett, J. A. Gracey

Using large N_f methods we compute the anomalous dimension of the predominantly gluonic flavour singlet twist-2 composite operator which arises in the operator product expansion used in deep inelastic scattering. We obtain a d-dimensional expression for it which depends on the operator moment n. Its expansion in powers of epsilon = (4-d)/2 agrees with the ex

L. Pasquali, M. H. Reno, I. Sarcevic

We present a calculation of the fluxes of muons and muon neutrinos from the decays of pions and kaons that are themselves the decay products of charmed particles produced in the atmosphere by cosmic ray-air collisions. Using the perturbative cross section for charm production, these lepton fluxes are two to three orders of magnitude smaller than the fluxes f

H. Meyer

This century has seen a dramatic increase in observational possibilities of the physics of the universe. Several of the very recent new developments with emphasis on the particle physics aspect and in particular Gamma-Gamma interactions are briefly discussed in this talk.

A. Giovannini, R. Ugoccioni

Superposition of jets of different flavors as well as superposition of jets of different topologies describe well observed structures (shoulder, H_q oscillations) in e+e- annihilation. The analysis of similar effects seen in experimental data in hadron-hadron collision is performed successfully by superimposing soft and semi-hard contributions at various ene

R. Ugoccioni, A. Giovannini

Starting from the recognized fact that oscillations of moments with rank and shoulder structure in the multiplicity distribution have the same origin in the full sample of events in e+e- annihilation, we push our investigation to the 2-jet sample level, and argue in favor of the use of the negative binomial multiplicity distribution as the building block of

S. Collins, C. T. H. Davies, G. Bali

We present results for the exotic $0^{+-}$ and $1^{-+}$ $b\bar{b}g$ hybrids at $β=6.0$. A leading order NRQCD action is used to generate the heavy quark propagators. The optimisation of operators is discussed and we compare our results to the predictions of recent potential calculations.

S. Aoki, G. Boyd, R. Burkhalter, S. Hashimoto

We present progress report of a CP-PACS calculation of quenched QCD spectrum with the Wilson quark action. Light hadron masses and meson decay constants are obtained at $β=$5.9, 6.1, and 6.25 on lattices with a physical extent of 3 fm, and for the range of quark mass corresponding to $m_π/m_ρ\approx 0.75$ $-$ 0.4. Nucleon mass at each $β$ appears to be a con

B. F. Schutz

The space-based gravitational wave detector LISA will observe in the low-frequency gravitational-wave band (0.1 mHz up to 1 Hz). LISA will search for a variety of expected signals, and when it detects a signal it will have to determine a number of parameters, such as the location of the source on the sky and the signal&#39;s polarisation. This requires patte

B. F. Schutz

Gravitational wave detectors in space, particularly the LISA project, can study a rich variety of astronomical systems whose gravitational radiation is not detectable from the ground, because it is emitted in the low-frequency gravitational wave band (0.1 mHz to 1 Hz) that is inaccessible to ground-based detectors. Sources include binary systems in our Galax

K. Nakamura, H. Ishihara

A self-gravitating cylindrical domain wall is considered as an example of non-spherical wall to clarify the interaction between a domain wall and gravitational waves. We consider the time evolution from a momentarily static initial configuration within an infinitesimal time interval using the metric junction formalism. We found that the wall with a large ini

Akihiro Ishibashi, Hideki Ishihara

The equation of motion for domain wall coupled to gravitational field is derived. The domain wall is treated as a source of gravitational field around the wall. The perturbed equation is also obtained with taking account of the gravitational back reaction on the motion of the domain wall.

A. Gopakumar, Bala R. Iyer

The post-post-Newtonian (2PN) accurate mass quadrupole moment, for compact binaries of arbitrary mass ratio, moving in general orbits is obtained by the multi-polar post Minkowskian approach of Blanchet, Damour, and Iyer (BDI). Using this, for binaries in general orbits, the 2PN contributions to the gravitational waveform, and the associated far-zone energy

Matt Visser

The energy conditions of classical Einstein gravity fail once quantum effects are introduced. These quantum violations of the energy conditions are not subtle high-energy Planck scale effects. Rather the quantum violations of the energy conditions already occur in semiclassical quantum gravity and are first-order O(\hbar) effects. Quantum violations of the e

Matt Visser

The ``reliability horizon&#39;&#39; for semi-classical quantum gravity quantifies the extent to which we should trust semi-classical quantum gravity, and gives a handle on just where the ``Planck regime&#39;&#39; resides. The key obstruction to pushing semi-classical quantum gravity into the Planck regime is often the existence of large metric fluctuations,

Garnett W. Bryant

A theory is presented to show how near-field optical microscopy can be used to probe quantum nanostructures. Calculations are done for a quantum dot. Results for different tip/dot configurations and sizes show that near-field excitation can enhance light-hole transitions, excite selection-rule breaking transitions with rates comparable to allowed transitions

J. A. Fernandez-Baca, P. Dai, H. Y. Hwang, S-W. Cheong

Elastic and inelastic neutron scattering was used to study two ferromagnetic manganites A$_{1-x}$B$_{x}$MnO$_3$ (x $\approx$ 0.3) with $T_c$=197.9 K and 300.9 K. The spin dynamical behavior of these is similar at low temperatures, but drastically different at temperatures around $T_c$. While the formation of spin clusters of size ($\sim20$ Å) dominates the s

M. Granath, H. Johannesson

We study the low-temperature thermodynamics of a spin-S magnetic impurity coupled to m degenerate bands of interacting electrons in one dimension. By exploiting boundary conformal field theory techniques, we derive exact results for the possible impurity thermal and magnetic response. The leading behavior of the impurity magnetic susceptibility is shown to b

H. Y. Hwang, P. Dai, S-W. Cheong, G. Aeppli

We have studied the spin dynamics in Pr$_{0.63}$Sr$_{0.37}$MnO$_3$ above and below the Curie temperature $T_C=301$ K. Three distinct new features have been observed: a softening of the magnon dispersion at the zone boundary for $T<T_C$, significant broadening of the zone boundary magnons as $T\to T_C$, and no evidence for residual spin-wave like excitations

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

In this paper the Martin-Siggia-Rose (MSR) functional integral representation is used for the study of the Langevin dynamics of a polymer melt in terms of collective variables: mass density and response field density. The resulting generating functional (GF) takes into account fluctuations around the random phase approximation (RPA) up to an arbitrary order.

Yoichi Ando, G. S. Boebinger, A. Passner, N. L. Wang

The normal-state Hall coefficient R_H and the in-plane resistivity ρ_{ab} are measured in La-doped Bi_{2}Sr_{2}CuO_{y} (T_c \simeq 13 K) single crystals and La_{2-x}Sr_{x}CuO_{4} thin films by suppressing superconductivity with 61-T pulsed magnetic fields. In contrast to data above T_c, the R_H below \sim 10 K shows little temperature dependence in all the s

Matteo Marsili, Paolo De Los Rios, Sergei Maslov

We study a recently proposed equation for the avalanche distribution in the Bak-Sneppen model. We demonstrate that this equation indirectly relates $τ$,the exponent for the power law distribution of avalanche sizes, to $D$, the fractal dimension of an avalanche cluster.We compute this relation numerically and approximate it analytically up to the second orde

U. Hohenester, P. Kocevar, P. L. de Andres, F. Flores

A systematic transport study of the ballistic electron emission microscopy (BEEM) of Au/Si(100) and Au/Si(111) Schottky barriers for different thicknesses of the metal layer and different temperatures is presented. It is shown that the existing experimental data are compatible with a recently predicted bandstructure-induced non-forward electron propagation t

C. Sanchez, E. P. M. Leiva

We perform high quality, first principles calculations of the properties of Pb and Tl isolated monolayers. Among these, we consider the equilibrium lattice constant, the two dimensional compressibilities and the electronic density. Comparison is made with previous results obtained using more simplified models. The present results represent an improvement con

Masashi Yamashiro, Nobukatsu Yoshida, Yukio Tanaka, Satoshi Kashiwaya

The properties of Josephson junction including a ferromagnetic insulating layer are studied theoretically. The calculated current shows the anomalous dependence on the magnitude of the exchange interaction at the interface. The Josephson junction changes from 0-junction to $π$-junction with the increase of the magnitude of the exchange interaction.

J. A. Verges

Kubo formula is used to get the d.c conductance of a statistical ensemble of two dimensional clusters of the square lattice in the presence of random magnetic fluxes. Fluxes traversing lattice plaquettes are distributed uniformly between minus one half and plus one half of the flux quantum. The localization length is obtained from the exponential decay of th

U. Hohenester, P. Kocevar, P. L. de Andres, F. Flores

We address the question of the spatial resolution of ballistic electron emission microscopy (BEEM) of Shottky barriers in Au(111)/Si(100) and Au(111)/Si(111) interfaces. A novel combination of Green-function and k-space Ensemble-Monte-Carlo techniques is used to obtain new insights into the spatial and energetic evolution of the STM-tip-induced electrons dur

T. Klotz, S. Schubert, K. H. Hoffmann

The state space of finite square and cubic Ising spin glass models is analysed in terms of the global and the local density of states. Systems with uniform and gaussian probability distribution of interactions are compared. Different measures for the local state density are presented and discussed. In particular the question whether the local density of stat

Enrico Carlon, Ferenc Igloi

We use the density matrix renormalization group (DMRG) to perform a detailed study of the critical properties of the two dimensional Q state Potts model, including the magnetization and energy-density profiles, bulk and surface critical exponents and the Casimir amplitudes. We apply symmetry breaking boundary conditions to a $L \times \infty$ strip and diago

O. Gunnarsson

We perform self-consistent Hartree calculations for a model of A_{3-x}C_{60} (A= K, Rb) to study the effects of the presence of vacancies. We find that the strong vacancy potential is very efficiently screened and that the density of states is only weakly influenced by the presence of vacancies.

Uri Alon, Martin Evans, Haye Hinrichsen, David Mukamel

A class of solid-on-solid growth models with short range interactions and sequential updates is studied. The models exhibit both smooth and rough phases in dimension d=1. Some of the features of the roughening transition which takes place in these models are related to contact processes or directed percolation type problems. The models are analyzed using a m

Mi-Ae Park, M. H. Lee, Yong-Jihn Kim

Compensation of the reduction of $T_{c}$ caused by magnetic impurities has been observed as a consequence of radiation damage. Using the recent theory by Kim and Overhauser (KO) we consider the effect of radiation damage on the $T_{c}$ of superconductors having magnetic impurities. We find a good fitting to the experimental data. It is also pointed out that

L. J. King, N. J. Jackson, R. D. Blandford, M. N. Bremer

We report the discovery, using NICMOS on the Hubble Space Telescope, of an arcsecond-diameter Einstein ring in the gravitational lens system B1938+666. The lensing galaxy is also detected, and is most likely an early-type. Modelling of the ring is presented and compared with the radio structure from MERLIN maps. We show that the Einstein ring is consistent w

Richard Watkins

We study the rms peculiar velocity of clusters as a convenient statistic to put constraints on cosmological models. This statistic is easy to compute theoretically given a model for the power spectrum; we show that with some assumptions it can be directly related to the quantity $Ω_0^{0.6}σ_8$. We develop a likelihood method for estimating the rms peculiar v

D. Vokrouhlicky, V. Karas

Long-term evolution of a stellar orbit captured by a massive galactic center via successive interactions with an accretion disc has been examined. An analytical solution describing evolution of the stellar orbital parameters during the initial stage of the capture was found. Our results are applicable to thin Keplerian discs with an arbitrary radial distribu

K. Boothby, M. Chantell, K. D. Green, D. B. Kieda

The Dual Imaging Cerenkov Experiment (DICE) was designed and operated for making elemental composition measurements of cosmic rays near the knee of the spectrum at several PeV. Here we present the first results using this experiment from the measurement of the average location of the depth of shower maximum, <X_max>, in the atmosphere as a function of partic

S. Cassisi, M. Salaris

Updated theoretical relations for the run of the bolometric and I magnitude of the Tip of the Red Giant Branch (TRGB) with respect to the metallicity are provided. An analogous relation for the V magnitude of the Zero Age Horizontal Branch at the RR Lyrae instability strip is also provided. A comparison has been performed among our ZAHB and TRGB distances, t

C. S. Kochanek, E. E. Falco, J. A. Munoz

We use simple comparisons of the optical and radio properties of the wide separation (3&#39;&#39; to 10&#39;&#39;) quasar pairs to demonstrate that they are binary quasars rather than gravitational lenses. The most likely model is that all the pairs are binary quasars, with a one-sided 2--sigma (1--sigma) upper limit of 22% (8%) on the lens fraction. Simple

Serge Winitzki, Arthur Kosowsky

A Gaussian distribution of cosmic microwave background temperature fluctuations is a generic prediction of inflation. Upcoming high-resolution maps of the microwave background will allow detailed tests of Gaussianity down to small angular scales, providing a crucial test of inflation. We propose Minkowski functionals as a calculational tool for testing Gauss

David M. Meyer, M. Jura, Jason A. Cardelli

Using the Goddard High Resolution Spectrograph (GHRS) onboard HST, we have obtained high S/N echelle observations of the weak interstellar O I 1356 A absorption toward the stars Gamma Cas, Epsilon Per, Delta Ori, Epsilon Ori, 15 Mon, Tau CMa, and Gamma Ara. In combination with previous GHRS measurements in six other sightlines (Zeta Per, Xi Per, Lambda Ori,

David M. Meyer, Jason A. Cardelli, Ulysses J. Sofia

Using the HST Goddard High Resolution Spectrograph (GHRS), we have obtained high S/N echelle observations of the weak interstellar N I 1160, 1161 A absorption doublet toward the stars Gamma Cas, Lambda Ori, Iota Ori, Kappa Ori, Delta Sco, and Kappa Sco. In combination with a previous GHRS measurement of N I toward Zeta Oph, these new observations yield a mea

Wolfgang P. Gieren, Pascal Fouque, Matias Gomez

We have used the infrared Barnes-Evans surface brightness technique to derive the radii and distances of 34 Galactic Cepheid variables. Radius and distance results obtained from both versions of the technique are in excellent agreement. The radii of 28 variables are used to determine the period-radius relation. This relation is found to have a smaller disper

A W Blain

One of the most direct routes for investigating the geometry of the Universe is provided by the numbers of strongly magnified gravitationally lensed galaxies as compared with those that are either weakly magnified or de-magnified. In the submillimetre waveband the relative abundance of strongly lensed galaxies is expected to be larger as compared with the op

H. M. Antia, S. M. Chitre

The primary inversion of the accurately measured frequencies of solar oscillations determines the mechanical properties of the Sun, i.e., the sound speed and density as a function of solar radius. In order to infer the temperature and hydrogen abundance profiles inside the Sun, it becomes necessary to use, in addition, the equations of thermal equilibrium al

Martin Asplund

Super-Eddington luminosities in hydrostatic model atmospheres manifest themselves by the presence of gas pressure inversions. Such inversions are not an artifact of the assumption of hydrostatic equilibrium but can also be present in hydrodynamical model atmospheres. Only for very large mass loss rates hardly realized in supergiants will the inversions be re

R. Alvarez, B. Plez

From near-infrared, narrow-band photometry of 256 oxygen-rich Mira variables we obtain evidence about the loops that these stars follow in colour-colour diagrams. We also find a phase lag between indices related to molecular band-strength of titanium oxide and vanadium oxide. We compute colours for normal M-giants and Miras using hydrostatic and hydrodynamic

A. Jorissen, G. R. Knapp

It is the purpose of this paper to rediscuss the circumstellar properties of S stars and to put these properties in perspective with our current understanding of the evolutionary status of S stars, in particular the intrinsic/extrinsic dichotomy. Accordingly, an extensive data set probing the circumstellar environment of S stars (IRAS flux densities, maser e

P. M. Ricker

We present numerical simulations of off-center collisions between galaxy clusters made using a new hydrodynamical code based on the piecewise-parabolic method (PPM) and an isolated multigrid Poisson solver. We have performed three gas-only high-resolution simulations of collisions between equal-mass clusters with different values of the impact parameter (0,

Masashi Chiba, Yuzuru Yoshii

The kinematics of 122 red giants and 124 RR Lyrae variables in the solar neighborhood is studied using accurate measurements of their proper motions by the Hipparcos astrometry satellite, combined with the published photometric distances, metal abundances and radial velocities. A majority of these sample stars have metal abundances with [Fe/H]<-1 and thus re

Sandra Di Rocco

In this notes we study $k$-jet ample line bundles $L$ on a non singular toric variety $X$, i.e. line bundles with global sections having arbitrarily prescribed $k$-jets at a finite number of points. We introduce the notion of an associated $k$-convex $\D$-support function, $ψ_L$, requiring that the polyhedra $P_L$ has edges of length at least $k$. This trans

Robin Hartshorne, Mireille Martin-Deschamps, Daniel Perrin

The aim of this paper is to prove a generalization of a theorem of Rao for families of space curves, which caracterizes the biliaison classes of curves. First we introduce the concept of pseudo-isomorphism of coherent sheaves, which generalizes the concept of stable isomorphism. An N-type resolution for a family of curves $C$ over the local ring $A$, defined

L. Brzezinski, B. Grzadkowski, Z. Hioki

The process of top-quark pair production followed by semileptonic decays at future high-energy e^+e^- linear colliders is investigated as a possible test of physics beyond the Standard Model. Assuming the most general non-standard forms for gamma t t-bar, Z t t-bar and Wtb couplings, the energy spectrum of the single lepton l^{+-} and the energy correlation

Eric Braaten, Yu-Qi Chen

We study the large-order asymptotic behavior of the perturbation series for short-distance coefficients in the NRQCD factorization formulas for the decays J/psi --> e^+e^- and eta_c --> gamma gamma. The short-distance coefficients of the leading matrix elements are calculated to all orders in the large-N_f limit. We find that there is a universal Borel resum

L. Frankfurt, A. Freund, M. Strikman

We demonstrate that perturbative QCD allows one to calculate the absolute cross section of diffractive exclusive production of photons at large $Q^2$ at HERA, while the aligned jet model allows one to estimate the cross section for intermediate $Q^2 \sim 2 GeV^2$. Furthermore, we find that the imaginary part of the amplitude for the production of real photon

N. G. Deshpande, B. Dutta, Sechul Oh

Motivated by the large branching ratios observed for the process $B\toη^{\prime}K$, we examine critically all the ingredients that go into estimates of B decays into two light pseudoscalars. Within factorization approximation, we examine several assumptions on the input parameters that could have a strong bearing on the predictions. Among these are (i) the Q

Ofer Aharony, Amihay Hanany, Barak Kol

We continue to study 5d N=1 supersymmetric field theories and their compactifications on a circle through brane configurations. We develop a model, which we call (p,q) Webs, which enables simple geometrical computations to reproduce the known results, and facilitates further study. The physical concepts of field theory are transparent in this picture, offeri

V. Barger, K. Cheung, D. P. Roy, D. Zeppenfeld

The weak charge $Q_W$ measured in atomic parity violation experiments can receive compensating contributions from more than one new physics source. We show explicitly that the $ΔQ_W$ contribution from the exchange of an extra Z-boson can cancel that from the $s$-channel scalar top or scalar charm exchange in R-parity violating SUSY models proposed to explain

ZEUS Collaboration

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of $x$ and $Q^2$ using the ZEUS detector. The evolution of the scaled momentum, $x_p$, with $Q^2,$ in the range 10 to 1280 $GeV^2$, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a singl

P. O. Fedichev, G. V. Shlyapnikov, J. T. M. Walraven

We present the theory of damping of low-energy excitations of a trapped Bose condensate at finite temperatures, where the damping is provided by the interaction of these excitations with the thermal excitations. We emphasize the key role of stochastization in the behavior of the thermal excitations for damping in non-spherical traps. The damping rates of the

A. Ritz

The constraints of N=2 supersymmetry, in combination with several other quite general assumptions, have recently been used to show that N=2 supersymmetric Yang-Mills theory has a low energy quantum parameter space symmetry characterised by the discrete group $\gu$. We show that if one also assumes the commutativity of renormalization group flow with the acti

David Lyth

Inflation is well known to be difficult in the context of supergravity, if the potential is dominated by the $F$ term. Non-renormalizable terms generically give $|V&#39;&#39;|\sim V/M^2$, where $V(ϕ)$ is the inflaton potential and $M$ is the scale above which the effective field theory under consideration is supposed to break down. This is equivalent to $|η|

G. M. Kavoulakis, C. J. Pethick, H. Smith

We calculate the damping of low-lying collective modes of a trapped Bose gas in the hydrodynamic regime, and show that this comes solely from the shear viscosity, since the contributions from bulk viscosity and thermal conduction vanish. The hydrodynamic expression for the damping diverges due to the failure of hydrodynamics in the outer parts of the cloud,

S. B. Goryachev

For the first time the phenomenon of cellular structure coarsening are consistently analysed from the positions of kinetic, hydrodynamic and stochastodynamic theories of nonequilibrium statistical systems. Thereby micro-, meso- and macroscopic levels of approach are distinguished. At the microscopic level the cellular structure is describe by a probability d

Taro Nakano, Junichiro Makino

We investigated the dynamical reaction of the central region of galaxies to a falling massive black hole by N-body simulations. As the initial galaxy model, we used an isothermal King model and placed a massive black hole at around the half-mass radius of the galaxy. We found that the central core of the galaxy is destroyed by the heating due to the black ho

Christian M. Dury, Gerald H. Ristow, Jamie L. Moss, Masami Nakagawa

The angle of repose for the flow of granular materials in a half-filled rotating drum is studied by means of experiments and computer simulations. Particles of different material properties are used to investigate the effects of the end caps on the angle of repose. By fitting the numerical results to an exponentially decaying function, we are able to calcula

Roberto A. Sussman

New exact solutions emerge by replacing the dust source of the Lemâitre-Tolman-Bondi metrics with a viscous fluid satisfying the monatomic gas equation of state. The solutions have a consistent thermodynamical interpretation. The most general transport equation of Extended Irreversible Thermodynamics is satisfied, with phenomenological coefficients bearing a