January 2000 arXiv papers — page 6

A. V. Tsiganov

Cubic invariants for two-dimensional degenerate Hamiltonian systems are considered by using variables of separation of the associated Stäckel problems with quadratic integrals of motion. For the superintegrable Stäckel systems the cubic invariant is shown to admit new algebro-geometric representation that is far more elementary than the all the known represe

Gregorio Falqui, Cesare Reina, Alessandro Zampa

We generalize to the supersymmetric case the representation of the KP hierarchy as a set of conservation laws for the generating series of the conserved densities. We show that the hierarchy so obtained is isomorphic to the JSKP of Mulase and Rabin. We identify its ``bosonic content'' with the so-called Darboux-KP hierarchy, which geometrically encom

Tomasz Brzezinski

A general deformation theory of algebras which factorise into two subalgebras is studied. It is shown that the classification of deformations is related to the cohomology of a certain double complex reminiscent of the Gerstenhaber-Schack complex of a bialgebra.

Daniel Ruberman

We reprove and extend a result of David Krebes (J. Knot Theory Ramif. 8 (1999), 321-352) giving an obstruction to embedding a tangle T into a link L. Closing the tangle up in the two obvious ways gives rise to two links, the numerator and denominator links n(T) and d(T). Applying a homological argument to the 2-fold branched covers of these links, we show th

Roberto Conti, Sergio Doplicher, John E. Roberts

An inclusion of observable nets satisfying duality induces an inclusion of canonical field nets. Any Bose net intermediate between the observable net and the field net and satisfying duality is the fixed-point net of the field net under a compact group. This compact group is its canonical gauge group if the occurrence of sectors with infinite statistics can

Guillermo Cortiñas

In this paper we study the fiber F of the rational Jones-Goodwillie character $$ F:=\hofiber(ch:K^\rat(A)@>>>HN^\rat(A)) $$ going from K-theory to negative cyclic homology of associative rings. We describe this fiber F in terms of sheaf cohomology. We prove that, for $n\ge 1$, there is an isomorphism: $$ π_n(F)\cong H^{-n}_{inf}(A,K^\rat) $$ between the homo

Vladimir D. Lyakhovsky

Multidimensional Heisenberg algebras, whose creation and annihilation operators are the N-dimensional vectors, can be injected into simple Lie algebras g. It is demonstrated that the spectrum of their deformations can be investigated using chains of extended Jordanian twists applied to U(g). In the case of U(sl(N)) (for N>5) the two-dimensional Heisenberg su

Alexander Reznikov

This is a paper in Analytic Topology.

Michael Eastwood, Vladimir Ezhov

We exhibit a family of homogeneous hypersurfaces in affine space, one in each dimension, generalising the Cayley surface.

A. Mironov, A. Morozov

This talk presents a list of problems related to the double-elliptic (Dell) integrable systems with elliptic dependence on both momenta and coordinates. As expected, in the framework of Seiberg-Witten theory the recently discovered explicit self-dual family of 2-particle Dell Hamiltonians provides a perturbative period matrix which is a logarithm of the rati

Donam Youm

We obtain the zero mode effective action for gravitating objects in the bulk of dilatonic domain walls. Without additional fields included in the bulk action, the zero mode effective action reproduces the action in one lower dimensions obtained through the ordinary Kaluza-Klein (KK) compactification, only when the transverse (to the domain wall) component of

Evgeny Ivanov, Galliano Valent

Starting from the most general harmonic superspace action of self-interacting Q^+ hypermultiplets in the background of N=2 conformal supergravity, we derive the general action for the bosonic sigma model with a generic 4n dimensional quaternionic-Kahler (QK) manifold as the target space. The action is determined by the analytic harmonic QK potential. We find

C. Adam, B. Muratori, C. Nash

One of the key properties of Dirac operators is the possibility of a degeneracy of zero modes. For the Abelian Dirac operator in three dimensions the construction of multiple zero modes has been sucessfully carried out only very recently. Here we generalise these results by discussing a much wider class of Dirac operators together with their zero modes. Furt

C. Adam, B. Muratori, C. Nash

We generalise recent results on Hopf instantons in a Chern--Simons and Fermion theory in a fixed background magnetic field. We find that these instanton solutions have to obey the Liouville equation in target space. As a consequence, these solutions are given by a class of Hopf maps that consist of the composition of the standard Hopf map with an arbitrary r

Verena Schoen, Michael Thies

QCD_2 with fundamental quarks on a cylinder is solved to leading order in the 1/N expansion, including the zero mode gluons. As a result of the non-perturbative dynamics of these gauge degrees of freedom, the compact space-time direction gets effectively decompactified. In a thermodynamic interpretation, this implies that there is no pressure of order N and

S. Aoyama

The reducible Kähler coset space G/S\otimesU(1)^k is discussed in a geometrical approach. We derive the formula which expresses the Riemann curvature of the reducible Kähler coset space in terms of its Killing vectors. The formula manifests the group structure of G. On the basis of this formula we establish an algebraic method to evaluate the four-fermi coup

M. Ripani, V. Mokeev, M. Anghinolfi, M. Battaglieri

The (π^{-}Δ^{++}) production on the nucleon by real and virtual photons is discussed as initial step in a simple model approach for the two pion photo- and electroproduction on the nucleon, with emphasis on nucleon resonance excitation which is of interest for new facilities like TJNAF. A calculation for (π^{-}Δ^{++}) channel in resonance excitation region i

R. A. Alanakyan

We consider bound states of fermions with an anomalous magnetic moments(neutrinos,neutrons) in radial electric and magnetic field of monopole.In case of radial magnetic field the interaction $\vecΣ\vec{H}$ violates P-parity and for this reason we must use the method of (hep-ph/9901248) where both components of spinor considererd as a linear combination of sp

Edward K. G. Sarkisyan

Various parametrizations of the multiplicity distribution are studied using the recently published large statistics OPAL results on multidimensional local fluctuations and genuine correlations in e+e- -> Z -> hadrons. The measured normalized factorial and cumulant moments are compared to the predictions of the negative binomial distribution, the modified and

S. Bondarenko, E. Gotsman, E. Levin, U. Maor

We formulate a generalization of the Glauber formalism for hadron-nucleus and nucleus-nucleus collisions based on the Pomeron approach to high energy interactions. Our treatment is based on two physical assumptions (i.e. two small parameters) : (i) that only sufficiently small distances contribute to the Pomeron structure; and (ii) the triple Pomeron vertex

Bing An Li

An effective theory of large N_{C} QCD of mesons has been used to study six K_{l4} decay modes. It has been found that the matrix elements of the axial-vector current dominate the K_{l4} decays. PCAC is satisfied. A relationship between three form factors of axial-vector current has been found. Non-zero phase shifts are originated in ρ-->ππ. The decay rates

D. I. Kazakov

An attempt is made to present modern hopes to find manifestation of supersymmetry, a new symmetry that relates bosons and fermions, in particle physics from the point of view of renormalization group flow. The Standard Model of particle interactions is briefly reviewed, the main notions of supersymmetry are introduced. In more detail the RG flow in the Minim

Gilberto Colangelo

I present a quick overview of the current status of Chiral perturbation theory in the meson sector. To illustrate the successes and some problems in the description of the phenomenology, I focus on a few selected examples that are relevant for DAFNE.

Robert Fleischer

The decays $B_d\toπ^+π^-$ and $B_s\to K^+K^-$ provide an interesting strategy to extract the CKM angle $γ$ at ``second-generation'' $B$-physics experiments of the LHC era. A variant for ``first-generation'' experiments can be obtained, if $B_s\to K^+K^-$ is replaced by $B_d\toπ^\mp K^\pm$. We show that the most recent experimental results for

N. V. Hieu, N. H. Son, N. V. Thanh, H. B. Thang

The quark-antiquark pairing due to the four-fermion direct coupling induced by the instantons in QCD is studied in the framework of the functional integral method. The integral equations for the order parameters are derived. Several classes of the solutions of these non-linear equations are considered in details. Their implications for the dynamical symmetry

M. J. Ramsey-Musolf

The study of parity-violation in semi-leptonic processes has yielded important insights into the structure of the Standard Model and the substructure of the nucleon. I discuss the future of semi-leptonic parity-violation and the role it might play in uncovering physics beyond the Standard Model.

Hooman Davoudiasl

We study the processes γ\e -> γ\e and γγ-> γγ, in the context of the proposal for Weak Scale Quantum Gravity (WSQG) with large extra dimensions. With an ultraviolet cutoff $M_S \sim 1$ TeV for the effective gravity theory, the cross sections obtained for these processes at the Next Linear Collider (NLC), with the \e γan γγoptions, deviate from the prediction

D. J. Miller, S. Moretti

The experimental reconstruction of the Higgs self-energy potential is essential to a verification of the Higgs boson's role in spontaneous electroweak symmetry breaking. The first step towards this goal, the measurement of the triple Higgs self-coupling, can possibly be accomplished at the next generation of linear colliders. Here we present a background

N. E. Ligterink, N. R. Walet, R. F. Bishop

We develop a consistent approach to Hamiltonian lattice gauge theory, using the maximal-tree gauge. The various constraints are discussed and implemented. An independent and complete set of variables for the colourless sector is determined. A general scheme to construct the eigenstates of the electric energy operator using a symbolic method is described. It

Beverly K. Berger, Vincent Moncrief

By applying a standard solution generating technique, we transform an arbitrary vacuum Mixmaster solution on $S^3 \times {\bf R}$ to a new solution which is spatially inhomogeneous. We thereby obtain a family of exact, spatially inhomogeneous, vacuum spacetimes which exhibit Belinskii, Khalatnikov, and Lifshitz (BKL) oscillatory behavior. The solutions are c

Stephane Fay

A dynamical study of the generalised scalar-tensor theory in the empty Bianchi type I model is made. We use a method from which we derive the sign of the first and second derivatives of the metric functions and examine three different theories that can all tend towards relativistic behaviours at late time. We determine conditions so that the dynamic be in ex

Vladimir S. Manko, Eckehard W. Mielke, José D. Sanabria-Gómez

A four-parameter class of exact asymptotically flat solutions of the Einstein-Maxwell equations involving only rational functions is presented. It is able to describe the exterior field of a slowly or rapidly rotating neutron star with poloidal magnetic field.

A. Tartaglia

We have developed a general geometric treatment of the GCE valid for any stationary axisymmetric metric. The method is based on the remark that the world lines of objects rotating along spacely circular trajectories are in any case, for those kind of metrics, helices drawn on the flat bidimensional surface of a cylinder. Applying the obtained formulas to the

J. P. Wilson

It is shown that the space-time with a conical singularity, which describes a thin cosmic string, is hyperbolic in the sense that a unique H^1 solution exists to the initial value problem for the wave equation with a certain class of initial data.

Guillermo Arreaga, Inyong Cho, Jemal Guven

The stability of a spherically symmetric self-gravitating magnetic monopole is examined in the thin wall approximation: modeling the interior false vacuum as a region of de Sitter space; the exterior as an asymptotically flat region of the Reissner-Nordström geometry; and the boundary separating the two as a charged domain wall. There remains only to determi

Ciprian Chelba

The paper presents a language model that develops syntactic structure and uses it to extract meaningful information from the word history, thus enabling the use of long distance dependencies. The model assigns probability to every joint sequence of words - binary-parse-structure with headword annotation. The model, its probabilistic parametrization, and a se

Ciprian Chelba, Frederick Jelinek

The paper presents a language model that develops syntactic structure and uses it to extract meaningful information from the word history, thus enabling the use of long distance dependencies. The model assigns probability to every joint sequence of words--binary-parse-structure with headword annotation and operates in a left-to-right manner --- therefore usa

B. R. Schlei, L. Prasad

We describe a simple, but efficient algorithm for the generation of dilated contours from bilevel images. The initial part of the contour extraction is explained to be a good candidate for parallel computer code generation. The remainder of the algorithm is of linear nature.

Ciprian Chelba, Frederick Jelinek

A new language model for speech recognition is presented. The model develops hidden hierarchical syntactic-like structure incrementally and uses it to extract meaningful information from the word history, thus complementing the locality of currently used trigram models. The structured language model (SLM) and its performance in a two-pass speech recognizer -

Juan J. Garcia-Ripoll, Victor M. Perez-Garcia

We study the stability and dynamics of vortices in two-species condensates as prepared in the recent JILA experiment (M. R. Andrews {\em et al.}, Phys. Rev. Lett. 83 (1999) 2498). We find that of the two available configurations, in which one specie has vorticity $m=1$ and the other one has $m=0$, only one is linearly stable, which agrees with the experiment

T. V. Shahbazyan, I. E. Perakis

The role of surface collective excitations in the electron relaxation in small metal particles is studied. It is shown that the dynamically screened electron-electron interaction in a nanoparticle contains a size-dependent correction induced by the surface. This leads to new channels of quasiparticle scattering accompanied by the emission of surface collecti

Ian Affleck, Jean-Sebastien Caux, Alexandre Zagoskin

Andreev scattering and the Josephson current through a one-dimensional interacting electron liquid sandwiched between two superconductors are re-examined. We first present some apparently new results on the non-interacting case by studying an exactly solvable tight-binding model rather than the usual continuum model. We show that perfect Andreev scattering (

Alessio Filippetti, Warren E. Pickett

The (001) surface of La_{1-x}Ca_xMnO_3 system in various magnetic orderings is studied by first principle calculations. A general occurrence is that z^2 dangling bond charge -- which is ``invisible'' in the formal valence picture -- is promoted to the bulk gap/Fermi level region. This drives a double-exchange-like process that serves to align the sur

B. I. Belevtsev, V. B. Krasovitsky, V. V. Bobkov, D. G. Naugle

The effect of crystal lattice disorder on the conductivity and colossal magnetoresistance in La_{1-x}Ca_{x}MnO_{3} (x \approx 0.33) films has been examined. The lattice defects are introduced by irradiating the film with high-energy (\simeq 6 MeV) electrons with a maximal fluence of about 2\times 10^{17} cm^{-2}. This comparatively low dose of irradiation pr

Dirk Hessinger, Martin Evers, Thomas Palberg

We report on sytematic measurements of the low frequency conductivity in aequous supensions of highly charged colloidal spheres. System preparation in a closed tubing system results in precisely controlled number densities between 1E16/m3 and 1E19/m^3 (packing fractions between 1E-7 and 1E-2) and electrolyte concentrations between 1E-7 and 1E-3 mol/l. Due to

Byron C. den Hertog, Michel J. P. Gingras

Recent experiments suggest that the Ising pyrochlore magnets ${\rm Ho_{2}Ti_{2}O_{7}}$ and ${\rm Dy_{2}Ti_{2}O_{7}}$ display qualitative properties of the spin ice model proposed by Harris {\it et al.} \prl {\bf 79}, 2554 (1997). We discuss the dipolar energy scale present in both these materials and consider how they can display spin ice behavior {\it despi

D. Taras-Semchuk, K. B. Efetov

We construct a supersymmetric field theory for the problem of a two-dimensional electron gas in a random, static magnetic field. We find a new term in the free energy, additional to those present in the conventional unitary sigma-model, whose presence relies on the long-range nature of the disorder correlations. Under a perturbative renormalization group ana

C. Groeber, R. Eder, W. Hanke

We present results of a systematic Quantum-Monte-Carlo study for the single-band Hubbard model. Thereby we evaluated single-particle spectra (PES & IPES), two-particle spectra (spin & density correlation functions), and the dynamical correlation function of suitably defined diagnostic operators, all as a function of temperature and hole doping. The results a

P. J. Thomas, J. C. Fenton, G. Yang, C. E. Gough

We describe two experimental approaches to circumvent the problem of self-heating in IV measurements on small mesa samples of 2212-BSCCO. Simultaneous dc and temperature measurements have been performed, allowing corrections for heating to be made. Short pulse measurements have also been made, where the IV characteristics and the mesa temperature can be meas

A. T. Varela, J. M. Sasaki, I. Guedes, P. T. C. Freire

X-ray scattering measurements are performed in order to verify % that the mechanism leading to the DC electric field induced $C_{2v}^{19} \to C_{2v}^{\neq 19}$ phase transition in KDP crystal at 119 K is the changing of the local sites symmetries of phosphate group from $C_2$ in the $C_{2v}^{19}$ phase to $C_s$ in the $C_{2v}^{\neq 19}$ phase. It is shown by

Antonio Coniglio, Mario Nicodemi

We briefly review the basics ideas and results of a recently proposed statistical mechanical approach to granular materials. Using lattice models from standard Statistical Mechanics and results from a mean field replica approach and Monte Carlo simulations we find a jamming transition in granular media closely related to the glass transition in super-cooled

Sadhan K. Adhikari

We present a numerical scheme for solving the time-independent nonlinear Gross-Pitaevskii equation in two dimensions describing the Bose-Einstein condensate of trapped interacting neutral atoms at zero temperature. The trap potential is taken to be of the harmonic-oscillator type and the interaction both attractive and repulsive. The Gross-Pitaevskii equatio

Th. Busch, J. R. Anglin

We use a multiple time scale boundary layer theory to derive the equation of motion for a dark (or `grey') soliton propagating through an effectively one-dimensional cloud of Bose-Einstein condensate, assuming only that the background density and velocity vary slowly on the soliton scale. We show that solitons can exhibit viscous or radiative acceleratio

A. Matulis, F. M. Peeters

The semi-classical conductance of a two-dimensional electron gas is calculated in the presence of a one-dimensional modulated magnetic field with zero average. In the limit of small magnetic field amplitudes (B) the contribution of the magnetic modulation to the magnetoresistance increases as $B^{3/2}$ in the diffusive limit, while the increase is linear in

Ali Naji, Shahin Rouhani

We investigate the non-perturbative results of multi-dimensional forced Burgers equation coupled to the continuity equation. In the inviscid limit, we derive the exact exponents of two-point density correlation functions in the universal region in arbitrary dimensions. We then find the universal generating function and the tails of the probability density fu

Th. Pruschke, R. Bulla, M. Jarrell

Wilson's Numerical Renormalization Group method is used to study the paramagnetic ground state of the periodic Anderson model within the dynamical mean-field approach. For the particle-hole symmetric model, which is a Kondo insulator, we find that the lattice Kondo scale T_0 is strongly enhanced over the impurity scale T_K; T_0/T_K ~ exp(1/3I), where I i

E. Scheer, J. C. Cuevas, A. Levy Yeyati, A. Martin-Rodero

Atomic quantum point contacts accommodate a small number of conduction channels. Their number N and transmission coefficients {T_n} can be determined by analyzing the subgap structure due to multiple Andreev reflections in the current-voltage (IV) characteristics in the superconducting state. With the help of mechanically controllable break-junctions we have

R. Mulet, H. Herrmann

We introduce two sets of continuum equations to describe granular flow on a free surface and study their properties. The equations derived from a microscopic picture that includes jumps and a mobility threshold, account for ripple and crater formation.

R. Carmi, E. Polturak, G. Koren, A. Auerbach

We report the observation of a weak spontaneous magnetic field appearing at the transition temperature of $\rm YBa_2Cu_3O_{7-δ}$ into the superconducting state. The effect is observed in 14 out of 15 epitaxial films grown on different substrates and by two distinct techniques. The average magnetic field sensed by the SQUID magnetometer is of the order of 10$

Per Bak, Kan Chen

We present a geometrical model of the distribution of luminous matter in the universe, derived from a very simple reaction-diffusion model of turbulent phenomena. The apparent dimension of luminous matter, $D(l)$, depends linearly on the logarithm of the scale $l$ under which the universe is viewed: $D(l) \sim 3\log(l/l_0)/\log(ξ/l_0)$, where $ξ$ is a correl

Kenneth M. Nollett, Scott Burles

We present a Monte Carlo method for direct incorporation of nuclear inputs in primordial nucleosynthesis calculations. This method is intended to remedy shortcomings of current error estimation, by eliminating intermediate data evaluations and working directly with experimental data, allowing error estimation based solely on published experimental uncertaint

Richard P. Nelson, John C. B. Papaloizou

We present SPH simulations of accretion discs in orbit about rotating compact objects such as black holes and neutron stars, and study the structure of warped discs produced by the Bardeen-Petterson effect. We calculate the transition radius out to which the disc specific angular momentum vector is aligned with that of the black hole. We focus on the paramet

Carl Akerlof, Richard Balsano, Scott Barthelmy, Jeff Bloch

The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure simultaneous and early afterglow optical emission from gamma-ray bursts (GRBs). A search for optical counterparts to six GRBs with localization errors of 1 square degree or better produced no detections. The earliest limiting sensitivity is m(ROTSE) > 13.1 at 10.85 seconds (5 second exp

L. Natalucci, A. Bazzano, M. Cocchi, P. Ubertini

The transient X-ray source SAX J1810.8-2609 was discovered on 1998, March 10 with the Wide Field Cameras on board the BeppoSAX satellite, while observing the Galactic Bulge in the 2-28 keV energy range. On March 11, a strong type-I X-ray burst was detected with evidence of photospheric radius expansion. A follow-up target of opportunity observation with the

Luigi Piro

The afterglow emission has become the main stream of Gamma-Ray burst research since its discovery three years ago. With the distance-scale enigma solved, the study of the late-time GRB emission is now the most promising approach to disclose the origin of these explosions and their relationship with the environment of the host galaxy in the early phase of the

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod

We present a 9 million star color-magnitude diagram (9M CMD) of the LMC bar. The 9M CMD reveals a complex superposition of different age and metallicity stellar populations, with important stellar evolutionary phases occurring over 3 orders of magnitude in number density. First, we count the non-variable supergiants, the associated Cepheids, and measure the

Leo Girardi

We briefly review the main features in the broad-band colour evolution of star clusters, over the complete age interval from 10^7 to 10^(10) yr. The emphasis is in the problem of age-dating distant young clusters (<2 Gyr) from their integrated colours. It is shown that U-B and B-V are less sensitive to metallicity than colours involving red pass-bands, like

Torsten A. Ensslin

A short review on theoretical implications of non-thermal emission (radio, extreme ultraviolet, high energy X-ray) from the intra-cluster medium is given. The origin of cluster radio halos and cluster radio relics is discussed within the framework of a network of processes producing a non-thermal electron population. Emphasis is given to the role of old, rem

David J. Haglin, Richard J. Roiger, Jon Hakkila, Geoffrey Pendleton

We describe the design of a suite of software tools to allow users to query Gamma-Ray Burst (GRB) data and perform data mining expeditions. We call this suite of tools a shed (SHell for Expeditions using Datamining). Our schedule is to have a completed prototype (funded via the NASA AISRP) by February, 2002. Meanwhile, interested users will find a partially

Coel Hellier, Jonathan Kemp, T. Naylor, Frank M. Bateson

We present the 45-yr record of EX Hya&#39;s lightcurve and discuss the characteristics of its 15 observed outbursts. We then concentrate on the 1998 outburst, reporting the first outburst X-ray observations. We discover an X-ray beat-cycle modulation, indicating that an enhanced accretion stream couples directly with the magnetosphere in outburst, confirming

R. Genzel, C. Pichon, A. Eckart, O. E. Gerhard

We report a new analysis of stellar dynamics in the Galactic centre, based on improved sky and LOS velocities for >100 stars within a few arcsec of SgrA*. Overall the motions do not deviate strongly from isotropy. For 32 stars with all 3 components determined the absolute, LOS and sky velocities agree well, as for a spherical cluster. The projected radial an

Pierre Billoir, Antoine Letessier-Selvon

In this note we argue that the galactic model chosen by E.-J. Ahn, G. Medina-Tanco, P.L. Bierman and T. Stanev in their paper discussing the origin of the highest energy cosmic rays, is alone responsible for the focussing of positive particles towards the North galactic pole. We discuss the validity of this model, in particular in terms of field reversals an

G. Israelian, R. Garcia Lopez, Rafael Rebolo

We present results on carbon, nitrogen, and oxygen abundances for a sample of unevolved metal-poor stars with metallicities in the range -0.3< [Fe/H]< -3. Oxygen abundances derived from different indicators are compared showing consistently that in the range 0.3 >[Fe/H]>-3.0, the [O/Fe] ratio increases from approximately 0 to 1. We find a good agreement betw

Remo Ruffini

Recent work on the dyadosphere of a black hole is reviewed with special emphasis on the explanation of gamma ray bursts. A change of paradigm in the observations of black holes is presented.

M. Tecza, R. Genzel, L. J. Tacconi, S. Anders

We report near-infrared integral field spectroscopy of the luminous merging galaxy NGC 6240. Stellar velocities show that the two K-band peaks separated by 1.6arcsec are the central parts of inclined, rotating disk galaxies with equal mass bulges. The dynamical masses of the nuclei are much larger than the stellar mass derived from the K-band light, implying

G. L. Israel, S. Campana, S. Covino, D. Dal Fiume

We report the results of a 1998 July BeppoSAX observation of a field in the SMC which led to the discovery of 345s pulsations in the X-ray flux of SAXJ0103.2-7209. The BeppoSAX X-ray spectrum is well fit by an absorbed power-law with photon index 1.0 plus a black body component with kT=0.1keV. The unabsorbed luminosity in the 2-10 keV energy range is 1.2x10^

Masao Mori, Andreas Burkert

Many clusters of galaxies contain an appreciable amount of hot gas, the intracluster medium. As a consequence, gas will be stripped from galaxies that move through the inter cluster medium, if the ram pressure exceeds the internal gravitational force. We study the interaction between the intracluster medium and an extended gas component of dwarf galaxies con

Andrew Gould

If the standard microlensing geometry is inverted so that the Einstein ring is projected onto the observer plane rather than the source plane, then the relations between the observables (θ_E,\tilde r_E) and the underlying physical quantities (M,π_rel) become immediately obvious. Here θ_E and \tilde r_E are the angular and projected Einstein radii, M is the m

Li-Xin Li

When magnetic field lines thread a rotating black hole&#39;s horizon and connect with remote astrophysical loads, the rotational energy of the black hole can be extracted through the Blandford-Znajek mechanism. Due to the rotation of the black hole, the magnetic field lines are twisted and toroidal components are generated. So poloidal electric currents are

P. Marronetti, M. Huq, P. Laguna, L. Lehner

We present approximate analytical solutions to the Hamiltonian and momentum constraint equations, corresponding to systems composed of two black holes with arbitrary linear and angular momentum. The analytical nature of these initial data solutions makes them easier to implement in numerical evolutions than the traditional numerical approach of solving the e

A. Coste, T. Gannon, Ph. Ruelle

In a remarkable variety of contexts appears the modular data associated to finite groups. And yet, compared to the well-understood affine algebra modular data, the general properties of this finite group modular data has been poorly explored. In this paper we undergo such a study. We identify some senses in which the finite group data is similar to, and diff

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

The Landau Zener method allows to measure very small tunnel splittings Δin molecular clusters Fe_8. The observed oscillations of Δas a function of the magnetic field applied along the hard anisotropy axis are explained in terms of topological quantum interference of two tunnel paths of opposite windings. Studies of the temperature dependence of the Landau Ze

T. Csorgo

We review particle interferometry before 2000, including: basics and formalism of quantum-statistical correlations; model-independent analysis of short-range correlations; Coulomb wave-function corrections and the core/halo picture for $n$-particle Bose-Einstein correlations; graph rules to calculate these correlations even with partial coherence in the core

W. M. Alberico, S. M. Bilenky, W. Grimus

The problem of the magnitude of the S--factor of the hep process $p + {^3\mathrm{He}} \to {^4\mathrm{He}} + e^+ + ν_e$ is one of the most important unsolved problems in nuclear astrophysics. The magnitude of $S(hep)$ has also an important impact on the interpretation of the Super-Kamiokande solar neutrino results in terms of neutrino oscillations. We point o

Michael Dine

We review some aspects of moduli in string theory. We argue that one should focus on {\it approximate moduli spaces}, and that there is evidence that such spaces exist non-perturbatively. We ask what it would mean for string theory to predict low energy supersymmetry. Aspects of two proposed mechanisms for fixing the moduli are discussed, and solutions to ce

Rudnei O. Ramos, F. A. R. Navarro

The dynamical symmetry breaking in a two-field model is studied by numerically solving the coupled effective field equations. These are dissipative equations of motion that can exhibit strong chaotic dynamics. By choosing very general model parameters leading to symmetry breaking along one of the field directions, the symmetry broken vacua make the role of t

L. Costamante, G. Ghisellini, P. Giommi, G. Tagliaferri

We report on the BeppoSAX observations of four &#34;extreme&#34; BL Lacs, selected to have high synchrotron peak frequencies. All have been detected also in the PDS band. For 1ES 0120+340, PKS 0548-322 and H 2356-309 the spectrum is well fitted by a convex broken power-law, thus locating the synchrotron peak around 1 - 4 keV. 1ES 1426+428 presents a flat ene

B. O. Kerbikov, Yu. A. Simonov

Magnetic moments of baryons composed of light and strange quarks are computed for the first time through the only parameter of the model -- string tension $σ$. Resulting theoretical values differ from the experimental ones typically by about 10%.

U. Dassanayake, S. Fraden, A. van Blaaderen

Specially synthesized silica colloidal spheres with fluorescent cores were used as model electrorheological fluids to experimentally explore structure formation and evolution under conditions of no shear. Using Confocal Scanning Laser Microscopy we measured the location of each colloid in three dimensions. We observed an equilibrium body-centered tetragonal

Christian Jaekel

Recently it has been shown that the Reeh-Schlieder property w.r.t. thermal equilibrium states is a direct consequence of locality, additivity and the relativistic KMS condition. Here we extend this result to ground states.

A. S. Wills, V. Dupuis, E. Vincent, J. Hammann

We have examined the nonconventional spin glass phase of the 2-dimensional kagome antiferromagnet (H_3 O) Fe_3 (SO_4)_2 (OH)_6 by means of ac and dc magnetic measurements. The frequency dependence of the ac susceptibility peak is characteristic of a critical slowing down at Tg ~ 18K. At fixed temperature below Tg, aging effects are found which obey the same

V. D. Gladush

The variational principle for a thin dust shell in General Relativity is constructed. The principle is compatible with the boundary-value problem of the corresponding Euler-Lagrange equations, and leads to ``natural boundary conditions&#39;&#39; on the shell. These conditions and the gravitational field equations which follow from an initial variational prin

Guillermo Cortiñas

Let $k$ be a field of characteristic zero, $\g$ a $k$-Lie algebra, $e:S\g@>>>U\g$ the symmetrization map. The PBW quantization is the one parameter family of associative products: $$ x\star_t y=\sum_{p=0}^\infty B_p(x,y)t^p\qquad (t\in k) $$ where $B_p$ is the homogeneous component of degree $-p$ of the map $B:S\g\otimes_kS\g@>>>S\g$, $B(x,y)=e^{-1}(exey)$.

Amitabha Lahiri

For the Becchi-Rouet-Stora-Tyutin (BRST) invariant extended action for any gauge theory, there exists another off-shell nilpotent symmetry. For linear gauges, it can be elevated to a symmetry of the quantum theory and used in the construction of the quantum effective action. Generalizations for nonlinear gauges and actions with higher order ghost terms are a

G. Stan, M. J. Bojan, S. Curtarolo, S. M. Gatica

Model calculations are presented which predict whether or not an arbitrary gas experiences significant absorption within carbon nanotubes and/or bundles of nanotubes. The potentials used in these calculations assume a conventional form, based on a sum of two-body interactions with individual carbon atoms; the latter employ energy and distance parameters whic

Adam D. Smith

We explore the conversion of classical secret-sharing schemes to quantum ones, and how this can be used to give efficient QSS schemes for general adversary structures. Our first result is that quantum secret-sharing is possible for any structure for which no two disjoint sets can reconstruct the secret (this was also proved, somewhat differently, by D. Gotte

Z. Haba

We consider a wave packet of a charged particle passing through a cavity filled with photons at temperature T and investigate its localization and interference properties. It is shown that the wave packet becomes localized and the interference disappears with an exponential speed after a sufficiently long path through the cavity.

Sumiyoshi Abe, A. K. Rajagopal

Based on the form invariance of the structures given by Khinchin&#39;s axiomatic foundations of information theory and the pseudoadditivity of the Tsallis entropy indexed by q, the concept of conditional entropy is generalized to the case of nonadditive (nonextensive) composite systems. The proposed nonadditive conditional entropy is classically nonnegative

Mark Zajac Gerald L. Jones, James A. Glazier

In this paper we argue that the pattern of cell movements in the morphogenetic process known as convergent extension can be understood as a energy minimization process, provided the cell-cell adhesive energy has a certain kind of anisotropy. This single simple property is sufficient cause for the type of cell elongation, alignment, and intercalation of a cel

A. K. Aringazin

In this paper, we apply Ritz variational approach to a new isochemical model of $H_2$ molecule suggested by Santilli and Shillady. We studied Gaussian, $V_g$, and exponential, $V_e$, screened Coloumb potential {\it approximations}, as well as the original Hulten potential, $V_h$, case. Both the Coloumb and exchange integrals have been calculated only for $V_