November 1999 arXiv papers — page 7

E. F. Aguilera, J. J. Kolata, F. M. Nunes, F. D. Becchetti

Reaction products from the interaction of 6He with 209Bi have been measured at energies near the Coulomb barrier. A 4He group of remarkable intensity, which dominates the total reaction cross section, has been observed. The angular distribution of the group suggests that it results primarily from a direct nuclear process. It is likely that this transfer/brea

Ivan Mukha

Nuclear decays into three-particle channels are considered in a few-body approach of hyperspherical harmonics with emphasis on simultaneous, or direct, emission of two protons. General conditions of direct decays are described and their main features, being experimentally established in decays of light nuclei, are reported. The analysis method based on an ex

A. G. Ramm

A detailed discussion of the Krein's results (applicable for solving the inverse scattering problem) is given with complete proofs.

L. Mangiarotti, G. Sardanashvily

It is emphasized that equivalent definitions of connections on modules over commutative rings are not so in noncommutative geometry.

[Pi-Gang Luan, H. C. Lee, R. B. Zhang]

We study the Hopf algebra structure and the highest weight representation of a multiparameter version of $U_{q}gl(2)$. The commutation relations as well as other Hopf algebra maps are explicitly given. We show that the multiparameter universal ${\cal R}$ matrix can be constructed directly as a quantum double intertwiner, without using Reshetikhin's trans

M. A. Aguilar, M. Socolovsky

Using fibre bundle theory we construct the universal covering group of U(n), $\tilde{U}(n)$, and show that $\tilde{U}(n)$ is isomorphic to the semidirect product $SU(n)\bigcirc {\scriptstyle s}$ R. We give a bijection between the set of projective representations of U(n) and the set of equivalence classes of certain unitary representations of $SU(n)\bigcirc

Peter R. Bending

In this paper, we give a universal family of curves of genus 2 whose jacobians have $\sqrt2$ multiplication fixed by the Rosati involution, and several results based on it, including isogenies between jacobians of curves, and jacobians of curves with quaternionic multiplication.

Daniel Ruberman

We use a 1-parameter version of gauge theory to investigate the topology of the diffeomorphism group of 4-manifolds. A polynomial invariant, analogous to the Donaldson polynomial, is defined, and is used to show that the diffeomorphism group of certain simply-connected 4-manifolds has infinitely generated π_0.

Carlos Gutierrez

For some full measure subset B of the set of iet's (i.e. interval exchange transformations) the following is satisfied: Let X be a $C^r$, $1\le r\le \infty$, vector field, with finitely many singularities, on a compact orientable surface M. Given a nontrivial recurrent point $p\in M$ of X, the holonomy map around p is semi-conjugate to an iet $E :[0,1) \

Franca Figliolini, Daniele Guido

In this note we study inclusions of second quantization algebras, namely inclusions of von Neumann algebras on the Fock space of a separable complex Hilbert space H, generated by the Weyl unitaries with test functions in closed, real linear subspaces of H. We show that the class of irreducible inclusions of standard second quantization algebras is non empty,

John Conway, Olaf Delgado Friedrichs, Daniel H. Huson, William P. Thurston

An entirely new and independent enumeration of the crystallographic space groups is given, based on obtaining the groups as fibrations over the plane crystallographic groups, when this is possible. For the 35 ``irreducible'' groups for which it is not, an independent method is used that has the advantage of elucidating their subgroup relationships. E

Pavel I. Katsylo, Giorgio Ottaviani

We prove that the moduli space of mathematical instanton bundles on ${\Bbb P}^3$ with $c_2=5$ is smooth.

Alexander Pushnitski

The new representation formula for the spectral shift function due to F.Gesztesy and K.A.Makarov is considered. This formula is extended to the case of relatively trace class perturbations.

Shrawan Kumar, Jesper Funch Thomsen

Let X be a quasiprojective smooth surface defined over an algebraically closed field of positive characteristic. We show that if X is Frobenius split then so is the Hilbert scheme Hilb^n(X) of n points in X. In particular, we get the higher cohomology vanishing for ample line bundles on Hilb^n(X) when X is projective and Frobenius split.

Xiaoping Xu

In this paper, we present a formal variational calculus of super functions in one real variable and find the conditions for a "matrix differential operator" to be a Hamiltonian superoperator. Moreover, we prove that conformal superalgebras are equivalent to certain Hamiltonian superoperators.

U. Bunke

The goal is to understand the index-theoretic aspects of the recent preprint of R. Nest and F. Radulescu, math.OA/9911042. The basic observation (due to E. Guenter/N. Higson) is that the index of the Toeplitz operator is equal to the index of an associated Callias type operator, i.e. a Dirac operator with potential, the index of which is easy to compute. We

Jean-Francois Burnol

I explain how the Lax-Phillips theory can be applied to a purely innovating time series and compute the corresponding scattering function. I then associate such a time series to an algebraic curve (of genus at least 1) over a finite field and show that the Riemann Hypothesis (proven long ago) holds if and only if the scattering is causal (this causality is n

Hubert L. Bray

We prove the Riemannian Penrose conjecture, an important case of a conjecture made by Roger Penrose in 1973, by defining a new flow of metrics. This flow of metrics stays inside the class of asymptotically flat Riemannian 3-manifolds with nonnegative scalar curvature which contain minimal spheres. In particular, if we consider a Riemannian 3-manifold as a to

F. Englert

A macroscopic universe may emerge naturally from a Planck cell fluctuation by unfolding through a stage of exponential expansion towards a homogeneous cosmological background. Such primordial inflation requires a large and presumably infinite degeneracy at the Planck scale, rooted in the unbounded negative gravitational energy stored in conformal classes. Th

S. Miyagi

We investigate Yang-Mills instantons on a 7-dimensional manifold of G_2 holonomy. By proposing a spherically symmetric ansatz for the Yang-Mills connection, we have ordinary differential equations as the reduced instanton equation, and give some explicit and numerical solutions.

Asad Naqvi

We construct propagators in Euclidean AdS(d+1) space-time for massive p-forms and massive symmetric tensors.

M. Bordag, D. V. Vassilevich

We calculate the Casimir force between two parallel plates if the boundary conditions for the photons are modified due to presence of the Chern-Simons term. We show that this effect should be measurable within the present experimental technique.

G. M. Gandenberger

Extending previous work on $a_2^{(1)}$, we present a set of reflection matrices, which are explicit solutions to the $a_n^{(1)}$ boundary Yang-Baxter equation. Unlike solutions found previously these are multiplet-changing $K$-matrices, and could therefore be used as soliton reflection matrices for affine Toda field theories on the half-line.

B. Geyer, D. M. Gitman, P. M. Lavrov

A short rewiev of covariant quantization methods based on BRST-antiBRST symmetry is given. In particular problems of correct definition of Sp(2) symmetric quantization scheme known as triplectic quantization are considered.

I. V. Kanatchikov

We show that the De Donder-Weyl (DW) covariant Hamiltonian field equations of any field can be written in Duffin-Kemmer-Petiau (DKP) matrix form. As a consequence, the (modified) DKP beta-matrices (5 X 5 in four space-time dimensions) are of universal significance for all fields admitting the DW Hamiltonian formulation, not only for a scalar field, and can b

A. H. Hoang, A. V. Manohar

We study the shift in the $Υ$ mass due to a non-zero charm quark mass. This shift affects the value of the $\bar{\rm MS}$ $b$-quark mass extracted from the $Υ$ system by about -20 MeV, due to an incomplete cancellation of terms that are non-analytic in the charm quark mass. The precise size of the shift depends on unknown higher order corrections, and might

Nikolaos Kidonakis, Vittorio Del Duca

We study the resummation of singular distributions for electroweak-boson production at large transverse momentum in hadronic collisions. We describe the factorization properties of the cross section near partonic threshold and construct the resummed cross section at next-to-leading logarithmic accuracy in moment space in terms of soft gluon anomalous dimensi

E. Torrente-Lujan

A search for inverse beta decay electron antineutrinos has been carried out using the 825 days sample of solar data obtained at SK. The absence of a significant signal, that is, contributions to the total SK background and their angular variations has set upper bounds on a) the absolute flux of solar antineutrinos originated from ${}^8 B$ neutrinos $Φ_{\barν

B. Magradze

The two-loop invariant (running) coupling of QCD is written in terms of the Lambert W function. The analyticity structure of the coupling in the complex Q^2-plane is established. The corresponding analytic coupling is reconstructed via a dispersion relation. We also consider some other approximations to the QCD beta-function, when the corresponding couplings

Andrzej Czarnecki

This talk gives an elementary introduction to the basic properties of positronium. Recent progress in theoretical studies of the hyperfine splitting and lifetime of the ground state is reviewed. Sensitivity of these precisely measured quantities to some New Physics effects is discussed.

Jaume Guasch, Wolfgang Hollik, Arnd Kraft

Charged Higgs particles are a common feature of many extensions of the Standard Model. While its existence with masses up to the TeV scale can be probed at the Tevatron Run II and LHC hadron colliders, a precise determination of its properties would have to wait for a high energy e+e- linear collider. We have computed the complete one-loop electroweak correc

Rafael Hurtado, John Morales, Carlos Quimbay

We calculate the nucleonic and pionic dispersion relations at finite temperature T and non-vanishing chemical potentials $(μ_f)$ in the context of an effective chiral theory that describes the strong and electromagnetic interactions for nucleons and pions. The dispersion relations are calculated in the broken chiral symmetry phase, where the nucleons are mas

A. N. Mitra

This is an editorial summary of the contents of a Book comprising a set of Articles by acknowledged experts dealing with the impact of Field Theory on major areas of physics (from elementary particles through condensed matter to strings), arranged subjectwise under six broad heads. The Book which emphasizes the conceptual, logical and formal aspects of the s

Barry R. Holstein

A brief introduction to the subject of chiral perturbation theory ($χ$pt) is presented, including a discussion of effective field theory and applications of $χ$pt in the arena of purely mesonic interactions as well as in the $πN$ sector.

Sanatan Digal, Rajarshi Ray, Supratim Sengupta, Ajit M. Srivastava

We describe a novel phenomenon in which vortices are produced due to resonant oscillations of a scalar field which is driven by a periodically varying temperature T, with T remaining much below the critical temperature $T_c$. Also, in a rapid heating of a localized region to a temperature {\it below} $T_c$, far separated vortex and antivortex can form. We co

Andre Sopczak

The latest preliminary results of the searches for Higgs bosons and Supersymmetric particles at LEP are reviewed. The results include the data-taking in 1999 up to center-of-mass energies of 196 GeV. The combination of the results from the four LEP experiments leads to a significant increase of the detection sensitivity. No indication of a signal has been ob

Christer Friberg

A high-energy lepton-lepton collider will give us a unique possibility to study e-gamma and gamma-gamma interactions at high energies. The high-energy photons can be generated by Compton back-scattering of laser light on the high-energy lepton beams. With slightly reduced luminosities for e-gamma and gamma-gamma collisions compared to the lepton-lepton colli

Yosef Nir

The special features of CP violation in the Standard Model are presented. The significance of measuring CP violation in B, K and D decays is explained. The predictions of the Standard Model for CP asymmetries in B decays are analyzed in detail. Then, four frameworks of new physics are reviewed: (i) Supersymmetry provides an excellent demonstration of the pow

Hirosi Ooguri

Plenary talk at the conference, LATTICE 99, held in Pisa, Itay from June 29 to July 3, 1999.

JLQCD Collaboration, S. Aoki, M. Fukugita, S. Hashimoto

We present a model-independent calculation of hadron matrix elements for all dimension-six operators associated with baryon number violating processes using lattice QCD. The calculation is performed with the Wilson quark action in the quenched approximation at $β=6/g^2=6.0$ on a $28^2\times 48\times 80$ lattice. Our results cover all the matrix elements requ

Stefano Bianco

This paper is aimed at giving a complete review of the latest (post-1998 Physics in Collision conference) experimental results on charm physics.

Y. A. Kulchitsky, M. V. Kuzmin, V. B. Vinogradov

The method of extraction of the $e/h$ ratio, the degree of non-compensation, of the electromagnetic compartment of the combined calorimeter is suggested. The $e/h$ ratio of $1.74\pm0.04$ has been determined on the basis of the 1996 combined calorimeter test beam data. This value agrees with the prediction that $e/h > 1.7$ for this electromagnetic calorimeter

Roberto Casadio

Thin shells in general relativity can be used both as models of collapsing objects and as probes in the space-time outside compact sources. Therefore they provide a useful tool for the analysis of the final fate of collapsing matter and of the effects induced in the matter by strong gravitational fields. We describe the radiating shell as a (second quantized

A. A. Louis, R. Finken, J. P. Hansen

We calculate for the first time the full phase-diagram of an asymmetric non-additive hard-sphere mixture. The non-additivity strongly affects the crystallization and the fluid-fluid phase-separation. The global topology of the phase-diagram is controlled by an effective size-ratio y_{eff}, while the fluid-solid coexistence scales with the depth of the effect

Michael C. Martin, Wayne R. McKinney

Two recently commissioned infrared beamlines on the 1.4 bending magnet port at the Advanced Light Source, LBNL, are described. Using a synchrotron as an IR source provides three primary advantages: increased brightness, very fast light pulses, and enhanced far-IR flux. The considerable brightness advantage manifests itself most beneficially when performing s

S. M. Komirenko, K. W. Kim, A. A. Demidenko, V. A. Kochelap

We analyze the Cerenkov emission of high-frequency confined acoustic phonons by drifting electrons in a quantum well. We find that the electron drift can cause strong phonon amplification (generation). A general formula for the gain coefficient, alpha, is obtained as a function of the phonon frequency and the structure parameters. The gain coefficient increa

Mark J. Bowick, David R. Nelson, Alex Travesset

We propose and analyze an effective free energy describing the physics of disclination defects in particle arrays constrained to move on an arbitrary two-dimensional surface. At finite temperature the physics of interacting disclinations is mapped to a Laplacian Sine-Gordon Hamiltonian suitable for numerical simulations. We then specialize to the case of a s

L. Craco, M. S. Laad, E. Müller-Hartmann

We investigate the effects of static, diagonal disorder in the $d=\infty$ Hubbard model by treating the dynamical effects of local Hubbard correlations and disorder on an equal footing. This is achieved by a proper combination of the iterated perturbation theory and the coherent potential approximation. Within the paramagnetic phase, we find that the renorma

S. Giorgini

We study the low-energy collective oscillations of a dilute Bose gas at finite temperature in the collisionless regime. By using a time-dependent mean-field scheme we derive for the dynamics of the condensate and noncondensate components a set of coupled equations, which we solve perturbatively to second order in the interaction coupling constant. This appro

V. I. Kozub, S. D. Baranovskii, I. Shlimak

Qualitatively new transport mechanism is suggested for hopping of carriers according to which the variable-range hopping (VRH) arises from the resonant tunneling between transport states brought into resonance by Coulomb potentials produced by surrounding sites with fluctuating occupations. A semiquantitative description of the hopping transport is given bas

G. E. Volovik

Two exotic objects are still not identified experimentally in chiral superfluids and superconductors. These are the half-quantum vortex, which plays the part of the Alice string in relativistic theories, and the hedgehog in the l-field, which is the counterpart of the Dirac magnetic monopole. These two objects of different dimensionality are topologically co

R. Haberkern, C. Roth, R. Knoefler, S. Schulze

We discuss the preparation of thin icosahedral films (Al-Cu-Fe and Al-Pd-Re) via the route of the amorphous (a-)phase which in some aspects is a precursor to the icosahedral phase. A direct transition from the a- to the i-phase occurs for Al-Cu-Fe films at 430 C on the time scale of minutes. The resulting films are of good quality as shown by diffraction and

Niels Asger Mortensen, Antti-Pekka Jauho, Karsten Flensberg

An inherent difficulty in studying mesoscopic effects in semiconductor--superconductor hybrid structures is the large Schottky barrier which often forms at the interface. A large technological effort has been invested in in improving the contact between the superconductor and the two-dimensional electron gas (2DEG) of a semiconductor heterostructure, and in

R. Haberkern, C. Roth, R. Knoefler, F. Zavaliche

Amorphous samples of Al-Cu-Fe were crystallized to the icosahedral phase under the control of electrical conductivity and thermopower at a rather small temperature of T=720 K. A comparison between different annealing states of the amorphous and the resulting quasicrystalline phase done on the same sample shows aston-ishing parallels in conductivity and large

S. P. Roshchupkin, A. I. Voroshilo

We theoretically investigate stimulated bremsstrahlung emission and absorption (SBEA) in the scattering of a relativistic electron by a nucleus in a multifrequency field of circularly polarized plane electromagnetic waves propagating in the same direction. The general relativistic expression for the SBEA probability is derived. It is demonstrated that the pr

Marcus Fleck, Andrzej M. Oles, Lars Hedin

We investigate the magnetic instabilities of the nondegenerate (s-band) and a degenerate (d-band) Hubbard model in two dimensions using many-body effects due to the particle-particle diagrams and Hund's rule local correlations. The density of states and the position of Van Hove singularity change depending on the value of next-nearest neighbor hopping t&

Yikihiro Okuno

We study the impurity effect in the time reversal symmetry (${\cal T}$) breaking superconductor based on the Bogoliubov-de Gennes (BdG) equations. In ${\cal T}$-violating superconductors, spontaneous currents are induced around the impurity. The current patterns around the impurity reflect the structures of the Cooper pairs. We investigate impurity problem n

J. Rosenfeld, N. E. Ligterink

The phase transition present in the linear-chain and square-lattice cases of the transverse Ising model is examined. The extended coupled cluster method (ECCM) can describe both sides of the phase transition with a unified approach. The correlation length and the excitation energy are determined. We demonstrate the ability of the ECCM to use both the weak- a

Atsuhiro Kitazawa, Kiyomi Okamoto

We reexamine the numerical study of the magnetized state of the S=3/2 spin chain with single ion anisotropy D(> 0) for the magnetization M=M_{S}/3, where M_{S} is the saturation magnetization. We find at this magnetization that for D<D_{c1}=0.387 the system is critical and the magnetization plateau does not appear. For D > D_{c1}, the parameter region is div

Penka I. Petkova

We study a phenomenological model for weak ferromagnetic Fermi liquids and investigate the properties of the spin waves in the model. The Landau kinetic equation is used to derive, in addition to the known Goldstone mode, a new spin-wave mode -- the first Silin-like ferromagnetic mode. We discuss the role of the interaction parameter F^a_1 on the behavior of

S. Daul

We consider a modified version of the one-dimensional Hubbard model, the t1-t2 Hubbard chain, which includes an additional next-nearest-neighbor hopping. It has been shown that at weak coupling this model has a Luttinger liquid phase or a spin liquid phase depending upon the ratio of t2 to t1. Additionally if the on-site interaction U is large enough, the gr

Dean J. Lee, Jong K. Lee

As pointed out by Linus Pauling in his classic work on the relationship between crystal packing and ionic radius ratio, a difference in atomic size can be accommodated more readily by an ordered structure than by a disordered one. Because of mathematical complexity, however, very few works have been reported for substitutional alloys. In this work, coherency

L. L. Goncalves, M. Lopez de Haro, J. Taguena-Martinez, R. B. Stinchcombe

The dynamic critical exponent and the frequency and wave-vector dependent susceptibility of the kinetic Ising model with Glauber dynamics on an alternating isotopic chain are examined. The analysis provides to our knowledge the first connection between a microscopic model and the Nagel scaling curve originally proposed to describe dielectric susceptibility m

K. Karpinska, Marta Z. Cieplak, S. Guha, A. Malinowski

Measurements of the resistivity, magnetoresistance and penetration depth were made on films of LaSrCuO with up to 12 at.% of Zn substituted for the Cu. The results show that the quadratic temperature dependence of the inverse square of the penetration depth, indicative of d-wave superconductivity, is not affected by doping. The suppression of superconductivi

Julien Kockelkoren, Mogens H. Jensen

We investigate the fixed points of a shell model for the turbulent advection of passive scalars introduced Jensen, Paladin and Vulpiani. The passive scalar field is driven by the velocity field of the popular GOY shell model. The scaling behavior of the static solutions is found to differ significantly from Obukhov-Corrsin scaling theta_n ~ k_n^(-1/3) which

Amelia C. Ramirez, Ronaldo E. de Souza, David Schade

We present an analysis of the orbital properties in 9 intermediate-redshifts cluster of the CNOC1 survey and we compare them to a control sample of 12 nearby clusters. Similar to the nearby elliptical galaxies, the bulge-dominated galaxies in clusters at redshifts ~0.1-0.4 present orbits that are more eccentric than those for disk-dominated galaxies. However

Curtis Manning, Daniel Stern, Hyron Spinrad, Andrew J. Bunker

In the course of our on-going search for serendipitous high-redshift LyA emission in deep archival Keck spectra, we discovered two LyA emission line candidates in a moderate dispersion ($λ/{Δλ} +~ 1200$) spectrogram. Both lines have high equivalent width (EW_{obs}>= 450A), low velocity dispersions ($σ_v ~ 60 km/s), and deconvolved effective radii $r_e ~ 1.0

F. Caputo, M. Marconi, I. Musella

From a theoretical study based on nonlinear, nonlocal and time-dependent convective pulsating models at varying mass and chemical composition, we present the predicted Period-Luminosity, Period-Color, Color-Color and Period-Luminosity-Color relations in the BVRIJK bands for Classical Cepheids. All the theoretical relations are, in various degrees, metallicit

John Ellis

The density budget of the Universe is reviewed, and then specific particle candidates for non-bayonic dark matter are introduced, with emphasis on the relevance of cosmic-ray physics. The sizes of the neutrino masses indicated by recent atmospheric and solar neutrino experiments may be too small to contribute much hot dark matter. My favoured candidate for t

Craig L. Sarazin

Cluster mergers drive shocks into the intracluster medium which heat and compress the thermal gas. X-ray observations of shocks can be used to determine the geometry and kinematics of the merger. Merger shocks should also accelerate relativistic particles. Electrons with gamma about 300 (E about 150 MeV) are expected to be particularly common. Relativistic p

L. Grenacher, Ph. Jetzer, D. Puy

We investigated the cooling mechanism due to H2 and HD molecules in order to determine the minimum temperature achievable by cold H2-HD clouds in cooling flow clusters.

Tomasz Bulik

The distance scale to gamma ray bursts has been a subject of scientific debate for almost thirty years. Up to the discovery of afterglows only indirect methods could be used to constrain the distance scale to this objects. I review some of these results, and show the current limits on the spatial distribution and luminosity function of GRBs. The results obta

David Charbonneau, Timothy M. Brown, David W. Latham, Michel Mayor

We report high precision, high cadence photometric measurements of the star HD 209458, which is known from radial velocity measurements to have a planetary mass companion in a close orbit. We detect two separate transit events at times that are consistent with the radial velocity measurements. In both cases, the detailed shape of the transit curve due to bot

Krzysztof Belczynski, Tomasz Bulik, Wojciech Zbijewski

Compact object mergers are one of the favorite models of GRBs. It has been noted that in opposition to the collapsars, compact object mergers do not necessarily take place in the host galaxies, and may travel outside of them. With the discovery of afterglows and identification of host galaxies one can measure the distribution of GRBs with respect to their ho

Ashish Asgekar, A. A. Deshpande

We report preliminary results of our study of linear polarization in the pulsar emission at 35 & 327 MHz. We have exploited for this purpose the spectral modulation resulting from the differential Faraday rotation across the observed band. We discuss the results on a few bright pulsars by comparing them with the existing measurements at higher radio frequenc

Tzihong Chiueh, Xiang-Ping Wu

Increasing evidences provided primarily by the cluster lensing and numerical simulations of cluster formation indicate that galaxy clusters may contain compact cores that are substantially smaller than the cores revealed by the X-ray observations of hot intracluster gas. In this paper we present a model that describes how two distinct cores can grow simultan

V. Castellani, S. Degl&#39;Innocenti, L. Girardi, M. Marconi

This paper deals with theoretical predictions for He burning models in a range of masses covering the so-called Red Giant Branch phase transition. Taking as a guideline the observational constraints given by Hipparcos parallaxes to the predicted luminosity of models originated from Red Giant progenitors with He core undergoing electron degeneracy, we compare

J. C. B. Papaloizou, J. D. Larwood

We present a new computation of the linear tidal interaction of a protoplanetary core with a thin gaseous disc in which it is fully embedded. For the first time a discussion of the orbital evolution of cores with eccentricity (e) significantly larger than the gas-disc scale height to radius ratio (H/r) is given. We find that the direction of orbital migratio

Aldo Treves, Roberto Turolla, Silvia Zane, Monica Colpi

As many as $10^9$ neutron stars populate the Galaxy, but only $\approx 10^3$ are directly observed as pulsars or as accreting sources in X-ray binaries. In principle also the accretion of the interstellar medium may make isolated neutron stars shine, and their weak luminosity could be detected in soft X-rays. Recent ROSAT observations have convincingly shown

Stefanie Komossa, Janek Meerschweinchen

We present a study of the X-ray variability properties and spectral shapes of five active galaxies all of which show extreme or enigmatic X-ray properties. We focus on QSO 0117-2837, RXJ0134.3-4258, and NGC 4051, and briefly comment on Mrk 1298 and 4C +74.26. The individual objects were originally partly selected as candidates to host warm absorbers on the b

Ashish Asgekar, A. A. Deshpande

High time-resolution observations of pulsars were carried out at 35 MHz, using the Gauribidanur Radio Telescope (India), to study the spectra of intrinsic pulse-to-pulse fluctuations. Our sample consists of a few bright pulsars, each of which was observed for $\sim$1000~seconds so as to obtain long sequences of single-pulse data. The results, in terms of flu

R. Alvarez, A. Lancon, B. Plez, P. R. Wood

Based on a new and large sample of optical and near-infrared spectra obtained at the Mount Stromlo and Siding Spring Observatories (Lancon & Wood 1998; Lancon & Wood, in preparation), spectrophotometric properties of cool oxygen- and carbon-rich Long Period Variables and supergiants are presented. Temperatures of oxygen-rich stars are assigned by comparison

Keisuke Taniguchi, Takashi Nakamura

A solution to an equilibrium of irrotational binary polytropic stars in Newtonian gravity is expanded in a power of ε=a_0/R, where R and a_0 are the separation of the binary system and the radius of each star for R=\infty. For the polytropic index n=1, the solutions are given almost analytically up to order ε^6. We have found that in general an equilibrium s

Robert Fender, David Rayner, Ray Norris, R. J. Sault

We report the discovery of circularly polarised radio emission from the radio-jet X-ray binary SS 433 with the Australia Telescope Compact Array. The flux density spectrum of the circular polarization, clearly detected at four frequencies between 1 - 9 GHz, has a spectral index of (-0.9 +/- 0.1). Multiple components in the source and a lack of very high spat

Patricia Whitelock, Michael Feast

The luminosities and periods of obscured AGB stars in the LMC are discussed using a combination of ISO and ground-based infrared photometry. The bolometric luminosities of these stars fall close to an extrapolation of the period-luminosity relation derived for oxygen-rich Mira variables, with both oxygen- and carbon-rich stars falling close to the same relat

E. Battaner, E. Florido

The large-scale structure of the Universe has been observed to be characterized by long filaments, forming polyhedra, with a remarkable 100-200 Mpc periodicity, suggesting a regular network. The introduction of magnetic fields into the physics of the evolution of structure formation provides some clues to understanding this unexpected lattice structure. A re

Hee-Won Lee, Siek Hyung

The young and compact planetary nebula IC 4997 is known to exhibit very broad wings with a width exceeding $5000 {\rm km s^{-1}}$ around H$α$. We propose that the broad wings are formed through Rayleigh-Raman scattering involving atomic hydrogen, by which Ly$β$ photons with a velocity width of a few $10^2 {\rm km s^{-1}}$ are converted to optical photons and

D. A. Demir

After promoting the phases of the soft masses to dynamical fields corresponding to Goldstone bosons of spontaneously broken global symmetries in the supersymmetry breaking sector, the next-to-minimal supersymmetric model is found to solve the $μ$ problem and the strong CP problem simultaneously with an invisible axion. The domain wall problem persists in the

Gregory P. Korchemsky, Dan Pirjol, Tung-Mow Yan

We compute the form factors parametrizing radiative leptonic decays of heavy mesons B^+\toγe^+νfor photon energies much larger than Λ_{QCD}, where perturbative QCD methods for exclusive processes can be combined with the heavy quark effective theory. The form factors can be reliably obtained in this region in an expansion in powers of Λ/E_γ. The leading term

Clifford V. Johnson, Amanda W. Peet, Joseph Polchinski

We study brane configurations that give rise to large-N gauge theories with eight supersymmetries and no hypermultiplets. These configurations include a variety of wrapped, fractional, and stretched branes or strings. The corresponding spacetime geometries which we study have a distinct kind of singularity known as a repulson. We find that this singularity i

T. Han, M. B. Magro

We consider the top-quark decay $t\to \tilde τb$ and $t\to τb \tildeχ^0_1$ via explicit R-parity violating interactions in SUSY theories. We discuss the observability of those channels at the Fermilab Tevatron collider. The existing Tevatron data indicate a 95% confidence level upper bound on the coupling to be less than 0.94(0.63) for a long-lived (short-li

Alexander Vilenkin

Eternally inflating universes can contain thermalized regions with different values of the cosmological parameters. In particular, the spectra of density fluctuations should be different, because of the different realizations of quantum fluctuations of the inflaton field. I discuss a general method for calculating probability distributions for such variable

Vassiliki Kalogera

Spin--orbit misalignment in coalescing compact binaries affects their gravitational radiation waveforms. When the misalignment angles are large (>30 degrees), the detection efficiency of the coalescence events can decrease significantly if the misalignment effects are not modeled. In this paper, we consider the formation of close compact binaries and calcula

Laurent Houart, Yolanda Lozano

We present a description of the type IIB NS-NS p-branes in terms of topological solitons in systems of spacetime-filling brane-antibrane pairs. S-duality implies that these spacetime-filling branes are NS9-branes, S-dual to the D9-branes of the type IIB theory. The possible vortex-like solutions in an NS9,anti-NS9 configuration are identified by looking at i

Boudewijn F. Roukema, Gary A. Mamon

Several observational analyses suggest that matter is spatially structured at $\approx 130h^{-1}Mpc$ at low redshifts. This peak in the power spectrum provides a standard ruler in comoving space which can be used to compare the local geometry at high and low redshifts, thereby constraining the curvature parameters. It is shown here that this power spectrum p

Ph. Ghosez, K. M. Rabe

The ground-state polarization of PbTiO3 thin films is studied using a microscopic effective Hamiltonian with parameters obtained from first-principles calculations. Under short-circuit electrical boundary conditions, (001) films with thickness as low as three unit cells are found to have a perpendicularly polarized ferroelectric ground state with significant

John Ellis

The physics and world-wide accelerator context for possible accelerator projects at CERN after the LHC are reviewed, including the expectation that an e+ e- linear collider in the TeV energy range will be built elsewhere. Emphasis is laid on the Higgs boson, supersymmetry and neutrino oscillations as benchmarks for physics after the LHC. The default option f

S. P. de Alwis, N. Irges

We analyze simple models of gauge mediated supersymmetry breaking in the context of supergravity. We distinguish two cases. One is when the messenger of the supersymmetry breaking is a non Abelian gauge force and the other is when the messenger is a pseudoanomalous U(1). We assume that these models originate from string theory and we impose the constraint of

M. Calixto

The structure constants for Moyal brackets of an infinite basis of functions on the algebraic manifolds M of pseudo-unitary groups U(N_+,N_-) are provided. They generalize the Virasoro and W_\infty algebras to higher dimensions. The connection with volume-preserving diffeomorphisms on M, higher generalized-spin and tensor operator algebras of U(N_+,N_-) is d

Eric Braaten, Bernd A. Kniehl, Jungil Lee

The polarization of prompt J/psi at the Fermilab Tevatron is calculated within the nonrelativistic QCD factorization framework. The contribution from radiative decays of P-wave charmonium states decreases, but does not eliminate, the transverse polarization at large transverse momentum. The angular distribution parameter alpha for leptonic decays of the J/ψi