January 2004 arXiv papers — page 21

B. Yerozolimsky

A new method of measurements of angular correlations in neutron decay is proposed. It excludes the need of precise spectroscopy of decay products and thus promises to make the systematic uncertainties of the results much lower than in experiments carried out up to day.

B. Jurado, C. Schmitt, K. -H. Schmidt, J. Benlliure

A new experimental approach is introduced to investigate the relaxation of the nuclear deformation degrees of freedom. Highly excited fissioning systems with compact shapes and low angular momenta are produced in peripheral relativistic heavy-ion collisions. Both fission fragments are identified in atomic number. Fission cross sections and fission-fragment e

Rodica Borcia, Domnic Merkt, Michael Bestehorn

In this paper we report on 2D numerical simulations concerning linear and nonlinear evolution of surface-tension-driven instability in two-fluid systems heated from below using classical and phase-field models. In the phase-field formalism, one introduces an order parameter called phase-field function to characterize thermodynamically the phases. All the sys

Karmadeva Maharana

Using the method of $su(1,1)$ spectrum generating algebra, we analyze one dimensional Schroedinger equation with potential in the form ${C\over{x^2} + {D\over{x}}$ to obtain a class of potentials giving similar eigenvalues. By a group analysis of the differential equation it is found that the symmetry gets enhanced for particular values of $C$ and $D$. The g

Giuseppe Gaeta

Symmetry methods are by now recognized as one of the main tools to attack deterministic differential equations (both ODEs and PDEs); the situation is quite different for what concerns stochastic differential equations: here, symmetry considerations are of course quite widely used by theoretical physicists, but a rigorous and general theory comparable to the

Ilijas Farah, Jindrich Zapletal

If I is a suitably definable sigma-ideal on the real line and the factor algebra of Borel sets modulo I is weakly distributive then the algebra carries a Maharam submeasure.

Daniel C. Isaksen

By now it is well known that there are two useful (objectwise or local) families of model structures on presheaves: the injective and projective. In fact, there is at least one more: the flasque. For some purposes, both the projective and the injective structure run into technical and annoying (but surmountable) difficulties for different reasons. The flasqu

Amparo Gil, Javier Segura, Nico M. Temme

Integral representations are derived for the parabolic cylinder functions $U(a,x)$, $V(a,x)$ and $W(a,x)$ and their derivatives. The new integrals will be used in numerical algorithms based on quadrature. They follow from contour integrals in the complex plane, by using methods from asymptotic analysis (saddle point and steepest descent methods), and are sta

Jouko Mickelsson

An invariant for twisted K theory classes on a 3-manifold is introduced. The invariant is then applied to the twisted equivariant classes arising from the supersymmetric Wess-Zumino-Witten model based on the group SU(2). It is shown that the classes defined by different highest weight representations of the loop group LSU(2) are inequivalent. The results are

Valeria Banica

In this paper we concentrate on the analysis of the critical mass blowing-up solutions for the cubic focusing Schrödinger equation with Dirichlet boundary conditions, posed on a plane domain. We bound the blow-up rate from below, for bounded and unbounded domains. If the blow-up occurs on the boundary, the blow-up rate is proved to grow faster than $(T-t)^{-

Amparo Gil, Javier Segura, Nico M. Temme

We describe a variety of methods to compute the functions $K_{ia}(x)$, $L_{ia}(x)$ and their derivatives for real $a$ and positive $x$. These functions are numerically satisfactory independent solutions of the differential equation $x^2 w'' +x w' +(a^2 -x^2)w=0$. In an accompanying paper (Algorithm xxx: Modified Bessel functions of imaginary orde

E. Ournycheva, B. Rubin

The well known formula of B. Fuglede expresses the mean value of the Radon k-plane transform on $R^n$ as a Riesz potential. We extend this formula to the space of $n \times m$ real matrices and show that the corresponding matrix k-plane transform $f \to \hat f$ is injective if and only if $n-k \ge m$. Different inversion formulas for this transform are obtai

S. M. Gonek

These expository lectures focus on the distribution of zeros of the Riemann zeta function. The topics include the prime number theorem, the Riemann hypothesis, mean value theorems, and random matrix models.

Valery Alexeev, Ludmil Katzarkov

G. Tian and S.K. Donaldson formulated a conjecture relating GIT stability of a polarized algebraic variety to the existence of a Kahler metric of constant scalar curvature. In [Don02] Donaldson partially confirmed it in the case of projective toric varieties. In this paper we extend Donaldson's results and computations to a new case, that of reductive va

James Allen Fill, Nevin Kapur

We derive asymptotics of moments and identify limiting distributions, under the random permutation model on m-ary search trees, for functionals that satisfy recurrence relations of a simple additive form. Many important functionals including the space requirement, internal path length, and the so-called shape functional fall under this framework. The approac

Michael Levin

We prove that for every compactum X and every integer $n \geq 2$ there are a compactum Z of $\dim \leq n$ and a surjective $UV^{n-1}$-map $r: Z \lo X$ having the property that: for every finitely generated abelian group G and every integer $k \geq 2$ such that $\dim_G X \leq k \leq n$ we have $\dim_G Z \leq k$ and r is G-acyclic, or equivalently: for every s

Michael Levin

We prove that for every abelian group G and every compactum X with $\dim_G X \leq n \geq 2$ there is a G-acyclic resolution $r: Z \lo X$ from a compactum Z with $\dim_G Z \leq n$ and $\dim Z \leq n+1$ onto X.

Peter G. O. Freund

Our understanding of the four basic concepts of Physics -- space, time, matter and force -- has undergone radical change in the course of work on unification, starting with Maxwell's unification of electricity with magnetism, all the way to present day string theory. What started as four independent concepts, with space and time postulated and the possib

Kimball A. Milton

The Casimir energies and pressures for a massless scalar field associated with $δ$-function potentials in 1+1 and 3+1 dimensions are calculated. For parallel plane surfaces, the results are finite, coincide with the pressures associated with Dirichlet planes in the limit of strong coupling, and for weak coupling do not possess a power-series expansion in 1+1

L. Chekhov

We calculate genus one corrections to Hermitian one-matrix model solution with arbitrary number of cuts directly from the loop equation confirming the answer previously obtained from algebro-geometrical considerations and generalizing it to the case of arbitrary potentials.

Masato Arai, Muneto Nitta, Norisuke Sakai

We discuss hypermultiplets admitting degenerate discrete vacua and BPS domain walls interpolating them. This talk is based on the original papers, hep-th/0307274, hep-th/0211103 and hep-th/0302028.

E. I. Guendelman, A. Kaganovich, E. Nissimov, S. Pacheva

First we briefly outline the general construction of Dp-brane models with dynamical tensions. We then proceed to a more detailed discussion of a modified string model where the string tension is related to the potential of (an external) world-sheet electric current. We show that cancellation of the pertinent conformal anomaly on the quantum level requires th

Pedro F. Gonzalez-Diaz

The existence of phantom energy in a universe which evolves to eventually show a big rip doomsday is a possibility which is not excluded by present observational constraints. In this letter it is argued that the field theory associated with a simple quintessence model is compatible with a field definition which is interpretable in terms of a rank-three axion

A. Yarom, R. Brustein

We show that fluctuations of bulk operators that are restricted to some region of space scale as the surface area of the region, independently of its geometry. Specifically, we consider two point functions of operators that are integrals over local operator densities whose two point functions falls off rapidly at large distances, and does not diverge too str

G. Sardanashvily, G. Giachetta

In this scientific preface to the first issue of International Journal of Geometric Methods in Modern Physics, we briefly survey some peculiarities of geometric techniques in quantum models.

Takao Suyama, Piljin Yi

We investigate a deformed matrix model proposed by Kazakov et.al. in relation to Witten's two-dimensional black hole. The existing conjectures assert the equivalence of the two by mapping each to a deformed c=1 theory called the sine-Liouville theory. We point out that the matrix theory in question may be naturally interpreted as a gauged quantum mechanics d

Evgeny Ivanov, Luca Mezincescu, Paul K. Townsend

The `Chern-Simons Quantum Mechanics' of a particle on CP(n|m) is shown to yield the fuzzy descriptions of these superspaces, for which we construct the non-(anti)commuting position operators. For a particle on the supersphere CP(1|1) = SU(2|1)/U(1|1), the particle's wave-function at fuzziness level 2s is shown to be a degenerate irrep of SU(2|1) desc

Sang Pyo Kim

We review the current issues of nonequilibrium phase transitions, in particular, in the early universe. Phase transitions cannot maintain thermal equilibrium and become nonequilibrium when the thermal relaxation time scale is greater than the dynamical time scale. Nonequilibrium phase transitions would have happened in certain evolution stages of the early u

E. Maina, S. Moretti, M. R. Nolten, D. A. Ross

We illustrate the impact of full one-loop weak corrections onto b-jet-, prompt-photon- and Z-production at Tevatron and Large Hadron Collider (LHC)

Michal Malinsky

The possibility of having relatively large non-decoupling effects of the heavy Higgs particles within the two-Higgs doublet extension of the electroweak standard model is briefly discussed and demonstrated on an example of the one-loop amplitude of the process e^+e^- -> W^+W^-

K. Cranmer, B. Mellado, W. Quayle, Sau Lan Wu

The sensitivity of the ATLAS experiment to low mass SM Higgs produced via Vector Boson Fusion mechanism with $H\to γγ$ is invest igated. A cut based event selection has been chosen to optimize the expected signal significance with this decay mode. A signal significance of 2. 2$ σ$ may be achieved for $M_H=130 \gev$ with 30 fb$^{-1}$ of accumulated luminosity

M. -P. Lombardo

QCD at finite density presents specific challenges to lattice gauge theory. Nonetheless, a region of the QCD phase diagram up to moderately large baryon chemical potentials has been successfully explored on the lattice and new results and idea are continuously emerging. I will outline the lattice formulation of QCD, introduce the calculational schemes curren

M. Lorente, P. Kramer

We propose the fundamental and two dimensional representation of the Lorentz groups on a (3+1)-dimensional hypercubic lattice, from which representations of higher dimensions can be constructed. For the unitary representation of the discrete translation group we use the kernel of the Fourier transform. From the Dirac representation of the Lorentz group (incl

Yannis K. Semertzidis

Electric dipole moment (EDM) experiments are at the fore-front of search for physics beyond the standard model. The next generation searches promise to improve by several orders of magnitude the current EDM sensitivity levels.

J. Manuel Garcia-Islas

This paper is twofold. First of all a complete unified picture of $n$-dimensional quantum gravity is proposed in the following sense: In spin foam models of quantum gravity the evaluation of spin networks play a very important role. These evaluations correspond to amplitudes which contribute in a state sum model of quantum gravity. In \cite{fk}, the evaluati

Sang Pyo Kim, Don N. Page

We introduce a canonical method for pair production by electromagnetic fields. The canonical method in the space-dependent gauge provides pair-production rate even for inhomogeneous fields. Further, the instanton action including all corrections leads to an accurate formula for the pair-production rate. We discuss various aspects of the canonical method and

A. E. Shalyt-Margolin

This work is an extension of the study into statistical mechanics of the early Universe that has been the subject in prior works of the author, the principal approach being the density matrix deformation. In the work it is demonstrated that the previously derived exponential ansatz may be successfully applied to the derivation of the free and average energy

Giovanni Imponente, Giovanni Montani

We present a detailed discussion of the inflationary scenario in the context of inhomogeneous cosmologies. After a review of the fundamental features characterizing the inflationary model, as referred to a homogeneous and isotropic Universe, we develop a generalization in view of including small inhomogeneous corrections in the theory. A second step in our d

G. Aprea, G. Montani, R. Ruffini

Working in the lagrangian framework, we develop a geometric theory in vacuum with propagating torsion; the antisymmetric and trace parts of the torsion tensor, considered as derived from local potential fields, are taken and, using the minimal action principle, their field equations are calculated. Actually these will show themselves to be just equations for

V. M. Khatsymovsky

Regge calculus configuration superspace can be embedded into a more general superspace where the length of any edge is defined ambiguously depending on the 4-tetrahedron containing the edge. Moreover, the latter superspace can be extended further so that even edge lengths in each the 4-tetrahedron are not defined, only area tensors of the 2-faces in it are.

Emanuele Berti, Vitor Cardoso, Shijun Yoshida

We compute for the first time very highly damped quasinormal modes of the (rotating) Kerr black hole. Our numerical technique is based on a decoupling of the radial and angular equations, performed using a large-frequency expansion for the angular separation constant_{s}A_{l m}. This allows us to go much further in overtone number than ever before. We find t

A. Kuiroukidis, D. B. Papadopoulos

We consider a massless scalar field, conformally coupled to the Ricci scalar curvature, in the pre-inflation era of a closed FLRW Universe. The scalar field potential can be of the form of the Coleman-Weinberg one-loop potential, which is flat at the origin and drives the inflationary evolution. For positive values of the conformal parameter ξ, less than the

M. R. Setare, Khaled Saaidi

In this letter we have considered the eigenvalues and eigenfunctions of relativistic massless scalar particle which conformally coupled to the background of Einstein universe. We found the eigenvalues and eigenfunctions exactly.

T. Harko, M. K. Mak

We consider some classes of solutions of the static, spherically symmetric gravitational field equations in the vacuum in the brane world scenario, in which our Universe is a three-brane embedded in a higher dimensional space-time. The vacuum field equations on the brane are reduced to a system of two ordinary differential equations, which describe all the g

Pankaj S. Joshi, Rituparno Goswami, Naresh Dadhich

We investigate here how the shearing effects present within a collapsing matter cloud influence the outcome of gravitational collapse in terms of formation of either a black hole or a naked singularity as the final end state. For collapse of practically all physically reasonable matter fields, we prove that it would always end up in a black hole if it is eit

J Gerard Wolff

This book develops the conjecture that all kinds of information processing in computers and in brains may usefully be understood as "information compression by multiple alignment, unification and search". This "SP theory", which has been under development since 1987, provides a unified view of such things as the workings of a universal Turing

Amparo Gil, Javier Segura, Nico M. Temme

Fortran 77 programs for the computation of modified Bessel functions of purely imaginary order are presented. The codes compute the functions $K_{ia}(x)$, $L_{ia}(x)$ and their derivatives for real $a$ and positive $x$; these functions are independent solutions of the differential equation $x^2 w'' +x w' +(a^2 -x^2)w=0$. The code also computes ex

Dana Mihai, George Sparling, Philip Tillman

It is proposed that Maxwell theory, with a topological term, in four non-commutative dimensions, where the co-ordinates obey the Heisenberg algebra, is an umbrella theory for the description of the two-dimensional Quantum Hall Effect (following the fluidic approach of Susskind and Polychronakos), the twistor analyses of self-dual gravity, solitons and instan

Akihisa Koga, Norio Kawakami, T. M. Rice, Manfred Sigrist

We investigate the Mott transitions in two-band Hubbard models with different bandwidths. Applying dynamical mean field theory, we discuss the stability of itinerant quasi-particle states in each band. We demonstrate that separate Mott transitions occur at different Coulomb interaction strengths in general, which merge to a single transition only under speci

I. N. Volovichev, G. N. Logvinov, O. Yu. Titov, Yu. G. Gurevich

In this Communication, it is shown that models used for describing generation and recombination of electrons and holes lead to disagreements with Maxwell's electrodynamics. Self-consistent expressions, more adequately depicting the actual physical processes of electron-hole recombination in semiconductors are obtained. It is shown that the electron and h

G. A. Rizzi, A. Cossaro, M. Petukhov, F. Sedona

We have measured the transformation of pseudomorphic Ni films on Pd(100) into their bulk fcc phase as a function of the film thickness. We made use of x-ray diffraction and x-ray induced photoemission to study the evolution of the Ni film and its interface with the substrate. The growth of a pseudomorphic film with tetragonally strained face centered symmetr

A. A. Shanenko

A dilute homogeneous 3D Fermi gas in the ground state is considered for the case of a repulsive pairwise interaction. The low-density (dilution) expansions for the kinetic and interaction energies of the system in question are calculated up to the third order in the dilution parameter. Similar to the recent results for a Bose gas, the calculated quantities t

J. Kallunki, J. Krug

Two mechanisms for the breakdown of step flow growth, in the sense of the appearance of steps of opposite sign to the original vicinality, are studied by kinetic Monte Carlo simulations and scaling arguments. The first mechanism is the nucleation of islands on the terraces, which leads to mound formation if interlayer transport is sufficiently inhibited. The

A. Alvermann, F. X. Bronold, H. Fehske

Based on a selfconsistent theory of localization we study the electron transport properties of a disordered system in the framework of the Anderson model on a Bethe lattice. In the calculation of the dc conductivity we separately discuss the two contributions to the current-current correlation function dominating its behaviour for small and large disorder. T

P. F. Gora

We show analytically that a linear transmitter with correlated Gaussian white noises displays a stochastic resonance. We discuss the relation of this problem to a generalized noisy logistic equation.

K. L. Henderson, C. F. Barenghi

In a recent experiment Finne et al. discovered an intrinsic condition for the onset of quantum turbulence in $^3$He-B, that q=alpha/(1-alpha&#39;)<1, where alpha and alpha&#39; are mutual friction parameters. The authors argued that this condition corresponds to Kelvin waves which are marginally damped, so for q>1 Kelvin waves cannot grow in amplitude and tr

Anders Johansen

This paper presents an exclusive classification of the largest crashes in Dow Jones Industrial Average (DJIA), SP500 and NASDAQ in the past century. Crashes are objectively defined as the top-rank filtered drawdowns (loss from the last local maximum to the next local minimum disregarding noise fluctuations), where the size of the filter is determined by the

Jean-Michel Caillol

We consider random walks on the surface of the sphere $S_{n-1}$ ($n \geq 2$) of the $n$-dimensional Euclidean space $E_n$, in short a hypersphere. By solving the diffusion equation in $S_{n-1}$ we show that the usual law $<r^2 > \varpropto t $ valid in $E_{n-1}$ should be replaced in $S_{n-1}$ by the generic law $<\cos θ> \varpropto \exp(-t/τ)$, where $θ$ de

G Gregoire, H Chate

We study the onset of collective motion, with and without cohesion, of groups of noisy self-propelled particles interacting locally. We find that this phase transition, in two space dimensions, is always discontinuous, including for the minimal model of Vicsek et al. [Phys. Rev. Lett. {\bf 75},1226 (1995)] for which a non-trivial critical point was previousl

B. Partoens, P. Singha Deo

We present a numerical study of the effect of the repulsive logarithmic inter-particle interaction on the ground state configuration and the frequency spectrum of a confined classical two-dimensional cluster containing a finite number of particles. In the case of a hard wall confinement all particles form one ring situated at the boundary of the potential. F

Masafumi Udagawa, Youichi Yanase, Masao Ogata

We study the vortex state of a layered superconductor with vertical line nodes on its Fermi surface when a magnetic field is applied in the ab-plane direction. We rotate the magnetic field within the plane, and analyze the change of low-energy excitation spectrum. Our analysis is based on the microscopic Bogoliubov-de Gennes equation and a convenient approxi

Parthapratim Biswas, Raymond Atta-Fynn, D. A. Drabold

An implementation of the Reverse Monte Carlo algorithm is presented for the study of amorphous tetrahedral semiconductors. By taking into account a number of constraints that describe the tetrahedral bonding geometry along with the radial distribution function, we construct a model of amorphous silicon using the reverse monte carlo technique. Starting from a

Ali Javey, Qian Wang, Woong Kim, Hongjie Dai

High performance p- and n-type single-walled carbon nanotube (SWNT) field-effect transistors (FETs) are obtained by using high and low work function metals, Pd and Al as source/drain (S/D) electrodes respectively. Ohmic contacts made to chemically intrinsic SWNTs, with no or small Schottky barriers (SB), afford high ON-state currents up to 20 uA per tube. Th

C. Capan, A. Bianchi, R. Movshovich, A. D. Christianson

We have measured the thermal conductivity of the heavy-fermion superconductor CeCoIn_5 in the vicinity of the upper critical field, with the magnetic field perpendicular to the c axis. Thermal conductivity displays a discontinuous jump at the superconducting phase boundary below critical temperature T_0 ~ 1 K, indicating a change from a second to first order

P. Buonsante, R. Franzosi, V. Penna

The Bose-Hubbard Hamiltonian capturing the essential physics of the arrays of interacting Bose-Einstein condensates is addressed, focusing on arrays consisting of two (dimer) and three (trimer) sites. In the former case, some results concerning the persistence of mean-field features in the energy spectrum of the symmetric dimer are extended to the asymmetric

Roberto Luzzi, Áurea R. Vasconcellos, J. Galvão Ramos

Some general considerations on the notion of entropy in physics are presented. An attempt is made to clarify the question of the differentiation between physical entropy (the Clausius-Boltzmann one) and quantities called entropies associated to Information Theory, which are in fact generating functionals for the derivation of probability distributions and no

J. Horvat, X. L. Wang, S. Soltanian, S. X. Dou

This paper was withdrawn because subsequent measurements produced results not always consistent with the ones presented in the paper.

J. Dyks, A. K. Harding, B. Rudak

We present the influence of the special relativistic effects of aberration and light travel time delay on pulsar high-energy lightcurves and polarization characteristics predicted by three models: the two-pole caustic model, the outer gap model, and the polar cap model. Position angle curves and degree of polarization are calculated for the models and compar

J. C. Martin, M. D. Koppelman, the HST Eta Carinae Treasury Project Team

We have measured the brightness variations in Eta Carinae for the past six years using the Hubble Space Telescope Space Telescope Imaging Spectrograph and Advanced Camera for Surveys. Unlike ground-based data, observations by the HST allow direct measurement of the brightness of the central star by resolving it from the surrounding bright ejecta. We find int

Rosalba Perna, Bryan M. Gaensler

Traditional searches for radio pulsars have targeted individual small regions such as supernova remnants or globular clusters, or have covered large contiguous regions of the sky. None of these searches has been specifically directed towards giant supershells, some of which are likely to have been produced by multiple supernova (SN) explosions from an OB ass

B. E. Robertson, N. Yoshida, V. Springel, L. Hernquist

We describe hydrodynamical simulations of galaxy formation in a Lambda cold dark matter (CDM) cosmology performed using a subresolution model for star formation and feedback in a multiphase interstellar medium (ISM). In particular, we demonstrate the formation of a well-resolved disk galaxy. The surface brightness profile of the galaxy is exponential, with a

Takahiko Matsubara, Alexander S. Szalay, Adrian C. Pope

Eigenmode analysis is one of the most promising methods of analyzing large data sets in ongoing and near-future galaxy surveys. In such analyses, a fast evaluation of the correlation matrix in arbitrary cosmological models is crucial. The observational effects, including peculiar velocity distortions in redshift space, light-cone effects, selection effects,

S. T. Strasser, A. R. Taylor

We present a 21-cm emission-absorption study towards extragalactic sources in the Canadian Galactic Plane Survey (CGPS). We have analyzed HI spectra towards 437 sources with S > 150 mJy, giving us a source density of 0.6 sources per square degree at arcminute resolution. We present the results of a first analysis of the HI temperatures, densities, and featur

J. B. Bell, M. S. Day, C. A. Rendleman, S. E. Woosley

A Type Ia supernova explosion likely begins as a nuclear runaway near the center of a carbon-oxygen white dwarf. The outward propagating flame is unstable to the Landau-Darrieus, Rayleigh-Taylor, and Kelvin-Helmholtz instabilities, which serve to accelerate it to a large fraction of the speed of sound. We investigate the Rayleigh-Taylor unstable flame at the

Francois Hammer, Hector Flores, YanChun Liang, XianZhong Zheng

Determination of the star formation rate can be done using mid-IR photometry or Balmer line luminosity after a proper correction for extinction effects. Both methods show convergent results while those based on UV or on [OII]3727 luminosities underestimate the SFR by factors ranging from 5 to 40 for starbursts and for luminous IR galaxies, respectively. Most

Sachiko Tsuruta

With the successful launch of Chandra and XMM/Newton X-ray space missions combined with the lower-energy band observations, time has arrived when careful comparison of thermal evolution theories of isolated neutron stars with observations will offer a better hope for distinguishing among various competing neutron star cooling theories. For instance, the late

T. Di Girolamo, M. Vietri, G. Di Sciascio

In light of the recent finding of the narrow clustering of the geometrically-corrected gamma-ray energies emitted by Gamma Ray Bursts (GRBs), we investigate the possibility to use these sources as standard candles to probe cosmological parameters such as the matter density Omega_m and the cosmological constant energy density Omega_Lambda. By simulating diffe

C. Watson, E. G. Zweibel, F. Heitsch, E. Churchwell

Ambient interstellar material may become entrained in outflows from massive stars as a result of shear flow instabilities. We study the linear theory of the Kelvin - Helmholtz instability, the simplest example of shear flow instability, in a partially ionized medium. We model the interaction as a two fluid system (charged and neutral) in a planar geometry. O

Bryan Gaensler

In the last 5-10 years, wide-field imaging capabilities and effective mosaicing algorithms have made possible a variety of ambitious interferometric surveys of the Galaxy, resulting in images of unprecedented sensitivity and resolution. Here I discuss some of the highlights from these new surveys. Amongst the new results are the identification of many new su

G. Fabbiano, A. Baldi, A. R. King, T. J. Ponman

We present the integrated 411 ks {\it Chandra} ACIS-S exposure of the Antennae galaxies (NGC 4038/39). Besides a rich population of point-like sources, this spectacular image reveals a spatially and spectrally complex hot diffuse gaseous component. For the first time we detect intense line emission from Fe, Ne, Mg and Si in The Antennae, and obtain a detaile

G. Chartas, M. Eracleous, E. Agol, S. C. Gallagher

We present new results uncovered by a re-analysis of a Chandra observation of the gravitationally lensed, low-ionization broad absorption line (LoBAL) quasar H 1413+117. Previous analyses of the same Chandra observation led to the detection of a strong, redshifted Fe Kalpha line from the combined spectrum of all images. We show that the redshifted Fe Kalpha

J. R. Rigby, G. H. Rieke

Determining the properties of starbursts requires spectral diagnostics of their ultraviolet radiation fields, to test whether very massive stars are present. We test several such diagnostics, using new models of line ratio behavior combining Cloudy, Starburst99 and up-to-date spectral atlases. For six galaxies we obtain new measurements of HeI 1.7 um / Brack

Thierry Baertschiger, Francesco Sylos Labini

In the gravitational evolution of a cold infinite particle distribution, two-body interactions can be predominant at early times: we show that, by treating the simple case of a Poisson particle distribution in a static universe as an ensemble of isolated two-body systems, one may capture the origin of the first non-linear correlated structures. The developed

Jesper Storm

Single epoch K-band photometry of 32 RR Lyrae stars in the young galactic globular cluster IC4499 is presented. The mean magnitudes have been estimated using the K-band template light-curves of Jones, Carney and Fulbright (1996). We derive an independent estimate of the distance and reddening for the cluster based on the new <Mk>-logP-[Fe/H] relation from Bo

C. Matt Bradford, Jonas Zmuidzinas

Although far-IR -- mm-wave astronomy has now been developing for several decades, access to this portion of the spectrum remains difficult and limited. Relative to their optical-wavelength counterparts, the submillimeter observatories are both small in units of wavelength and hot in units of photon energy, which imposes limits on their angular resolution and

S. J. Smartt, J. R. Maund, M. A. Hendry, C. A. Tout

We present the discovery of a red supergiant star that exploded as supernova 2003gd in the nearby spiral galaxy M74. The Hubble Space Telescope (HST) and the Gemini Telescope imaged this galaxy 6 to 9 months before the supernova explosion and subsequent HST images confirm the positional coincidence of the supernova with a single,resolved star which is an 8 +

T. V. Mishenina, C. Soubiran, V. V. Kovtyukh, S. A. Korotin

We have performed the detailed analysis of 174 high-resolution spectra of FGK dwarfs obtained with the ELODIE echelle spectrograph at the Observatoire de Haute-Provence. Abundances of Fe, Si and Ni have been determined from equivalent widths under LTE approximation, whereas abundances of Mg have been determined under NLTE approximation using equivalent width

U. Lisenfeld, T. Wilding, G. G. Pooley, P. Alexander

We present high-sensitivity radio continuum observations with the VLA and Ryle Telescope at 1.5, 4.9, 8.4 and 15.4 GHz of the dwarf irregular galaxy NGC 1569. The radio data show an extended, irregularly-shaped halo with filamentary structure around the galaxy. The spectral index maps reveal an unusually patchy distribution with regions of flat spectral inde

Daisuke Kawata, Brad K. Gibson

We study the chemodynamical evolution of elliptical galaxies and their X-ray and optical properties using high-resolution cosmological simulations. Our Tree N-body/SPH code includes a self-consistent treatment of radiative cooling, star formation, supernovae feedback, and chemical enrichment. We present a series of LCDM cosmological simulations which trace t

Eduardo Bravo, Domingo Garcia-Senz

We have explored in three dimensions the fate of a massive white dwarf as a function of different initial locations of carbon ignition, with the aid of a SPH code. The calculated models cover a variety of possibilities ranging from the simultaneous ignition of the central volume of the star to the off-center ignition in multiple scattered spots. In the forme

Kenji Bekki, Masashi Chiba

We first demonstrate that globular cluster G1 could have been formed by tidal interaction between M31 and a nucleated dwarf galaxy (dE,N). Our fully self-consistent numerical simulations show that during tidal interaction between M31 and G1&#39;s progenitor dE,N with $M_{\rm B}$ $\sim$ -15 mag and its nucleus mass of $\sim$ $10^7$ $M_{\odot}$, the dark matte

S. Trudolyubov, O. Kotov, W. Priedhorsky, F. Cordova

We present the results of XMM-Newton survey of the northern part of the disk of M31. The results of a spectral and timing analysis of the thirty seven brightest sources are presented. Combining the results of X-ray analysis with available data at other wavelengths, we were able to classify ~50%, or 19 out of 37 sources. Two sources in our sample were previou

Michael Politano

The present-day formation of cataclysmic variables (CVs) with brown dwarf (BD) secondaries (0.013 M_sun < M_sec < 0.075 M_sun) is investigated using a population synthesis technique. Results from the latest, detailed models for BDs have been incorporated into the population synthesis code. For our models, we find that ZACVs with BD secondaries have orbital p

Gulab C. Dewangan, Takamitsu. Miyaji, Richard E. Griffiths, Ingo Lehmann

We present three XMM-Newton observations of the ultra-luminous compact X-ray source Holmberg II X-1 in its historical brightest and faintest states. The source was in its brightest state in April 2002 with an isotropic X-ray luminosity of 2e40 erg/s but changed to a peculiar low/soft state in September 2002 in which the X-ray flux dropped by a factor of four

Narutaka Ozawa

We prove a Kurosh type theorem for free-product type II_1 factors. In particular, if M = LF_2 \otimes R, then the free-product type II_1 factors M*...*M are all prime and pairwise non-isomorphic. This paper is a continuation of [N. Ozawa, Solid von Neumann algebras] and [N. Ozawa and S. Popa, Some prime factorization results for type II_1 factors].

Milos Milosavljevic, Abraham Loeb

The discovery of hundreds of young, bright stars within a parsec from the massive black hole at the center of the Galaxy presents a challenge to star formation theories. The requisite Roche densities for the gravitational collapse of gas clouds are most naturally achieved in accretion disks. The water maser sources in Keplerian rotation in the nuclei of NGC4

G. Bakos, R. W. Noyes, G. Kovacs, K. Z. Stanek

We discuss the system requirements for obtaining millimagnitude photometric precision over a wide field using small aperture short focal length telescope systems, such as are being developed by a number of research groups to search for transiting extra-solar planets. We describe the Hungarian-made Automated Telescope (HAT) system which attempts to meet these

A. Belyaev, M-H. Genest, C. Leroy, R. Mehdiyev

We evaluate the potential of the CERN LHC collider to observe rare decays of the top quark in channels involving R-parity violating (RPV) interactions. We stress the importance of calculating top quark production and decay simultaneously as a true 2->4 process. The process of tt-bar pair production followed by RPV decay of one of the top quarks is analyzed w

S. Pozzorini

We consider virtual electroweak corrections to the form factors for massless chiral fermions coupling to an SU(2)xU(1) singlet gauge boson in the asymptotic region $s\gg M_W^2$, where the invariant mass $s$ of the external gauge boson is much higher than the weak-boson mass scale. Using the sector-decomposition method we compute mass singularities, which ari

Vasilis Niarchos

In a previous paper (hep-th/0304045) it has been argued that tachyonic Dirac-Born-Infeld (DBI) actions can be obtained from open string theory in a limit, which generalizes the usual massless DBI limit. In the present note we review this construction focusing on a key property of the proposed tachyon effective actions: how they reproduce appropriate Venezian