December 2002 arXiv papers — page 8

W. Bietenholz, F. Hofheinz, J. Nishimura

We investigate two models in non-commutative (NC) field theory by means of Monte Carlo simulations. Even if we start from the Euclidean lattice formulation, such simulations are only feasible after mapping the systems onto dimensionally reduced matrix models. Using this technique, we measure Wilson loops in 2d NC gauge theory of rank 1. It turns out that the

Bert Janssen, Yolanda Lozano

We argue that the giant graviton configurations known from the literature have a complementary, microscopical description in terms of multiple gravitational waves undergoing a dielectric (or magnetic moment) effect. We present a non-Abelian effective action for these gravitational waves with dielectric couplings and show that stable dielectric solutions exis

T. Damour, M. Henneaux, H. Nicolai

It is shown in detail that the dynamics of the Einstein-dilaton-p-form system in the vicinity of a spacelike singularity can be asymptotically described, at a generic spatial point, as a billiard motion in a region of Lobachevskii space (realized as an hyperboloid in the space of logarithmic scale factors). This is done within the Hamiltonian formalism, and

A. S. Goldhaber, A. Rebhan, P. van Nieuwenhuizen, R. Wimmer

We first discuss how the longstanding confusion in the literature concerning one-loop quantum corrections to 1+1 dimensional solitons has finally been resolved. Then we use 't Hooft and Veltman's dimensional regularization to compute the kink mass, and find that chiral domain wall fermions, induced by fermionic zero modes, lead to spontaneous parity

H. Leutwyler

The lectures review some of the basic concepts relevant for an understanding of the low energy properties of the strong interactions: chiral symmetry, spontaneous symmetry breakdown, Goldstone bosons, quark condensate. The effective field theory used to analyze the low energy structure is briefly sketched. As an illustration, I discuss the implications of th

H. Leutwyler

I draw attention to a recent breakthrough in the field of low energy pion physics: the consequences of the hidden symmetry of the QCD Hamiltonian have successfully been incorporated in the general dispersive framework for the pi-pi scattering amplitude, which is due to Roy. The meagre experimental information about the imaginary parts at and above 0.8 GeV su

Yu. P. Ivanov, J. Huefner, B. Z. Kopeliovich, A. V. Tarasov

Elastic virtual photoproduction of charmonia on nucleons is calculated in a parameter free way with the light-cone dipole formalism and the same input: factorization in impact parameters, light-cone wave functions for the photons and the charmonia, and the universal phenomenological dipole cross section which is fitted to other data. The charmonium wave func

Alejandro Ayala

We study the behavior of the pion dispersion relation in a pion medium at finite density and temperature, introducing a chemical potential to describe the finite pion number density. Such description is particularly important during the hadronic phase of a relativistic heavy-ion collision, between chemical and thermal freeze-out, where the pion number changi

Maria Elena Tejeda-Yeomans

A summary is presented of the most recent matrix elements for massless 2 to 2 scattering processes calculated at two loops in QCD perturbation theory together with a brief review on the calculational methods and techniques used.

D. Bartz, Fl. Stancu

We study the short-range nucleon-nucleon interaction in a nonrelativistic chiral constituent quark model by diagonalizing a Hamiltonian containing a linear confinement and a Goldstone boson exchange interaction between quarks. A finite six-quark basis obtained from single particle cluster model states was previously used. Here we show that the configurations

O. V. Selyugin, M. Lokajíček, V. Kundrát

A behavior of imaginary and real parts of the high-energy elastic hadron scattering amplitude is examined in the diffraction region. It is shown that the interference between Coulomb and hadronic scattering at small momentum transfers and especially in the region of diffractive minimum can bring some information about the structure of the hadron spin-non-fli

A. Patkos, Zs. Szep, P. Szepfalusy

The enhancement of the scalar-isoscalar spectral function near the two-pion threshold is studied in the framework of an effective linear $σ$ model, using a large N approximation in the number of the Goldstone bosons. The effect is rather insensitive to the detailed T=0 characteristics of the $σ$ pole, it is accounted by a pole moving with increasing $T$ alon

O. V. Selyugin

The high energy elastic nucleon cross section is treated from the viewpoint of the basic principles of local field theory. The connection between the energy dependence of $σ_{tot}$ and the $ρ$ - ratio of the real to imaginary parts of the forward elastic scattering amplitude is examined in the framework of dispersion relations, derivative dispersion relation

Bing He, Hu Li, C. M. Shakin, Qing Sun

Recently there has been a great deal of interest in studying the properties of dense quark matter, with particular reference to diquark condensates and color superconductivity. In the present work we report calculations made for the excitations of quark matter for relatively low densities of the deconfined phase and in the absence of meson or diquark condens

A. A. Arkhipov

The importance of cosmic-ray experimental measurements of proton-proton total cross sections to understand the underlying fundamental dynamics is discussed. It is shown that early discovered global structure of proton-proton total cross section [5,17] is completely compatible with the values obtained from cosmic-ray experiments.

H. Ichie, V. Bornyakov, T. Streuer, G. Schierholz

We study the abelian color flux of two- and three-quark systems in the maximally abelian gauge in lattice QCD with dynamical fermions. We find that the abelian flux tube formed between quark and antiquark is very much the same as in quenched QCD up to quark separations of $R$$\sim$ 2fm. The profile of the color electric field in three-quark system suggests $

K. Filimonov

High pT hadrons produced in ultra-relativistic heavy-ion collisions at RHIC probe nuclear matter at extreme conditions of high energy density. Experimental measurements in Au+Au collisions at \sqrtsNN=130, 200 GeV establish the existence of strong medium effects on hadron production well into the perturbative regime.

Ivan De Mitri

The results of dark matter searches with the MACRO experiment are reported. In particular indirect searches for WIMP's and direct searches for supermassive GUT magnetic monopoles are reported together with massive neutrino studies through the measurement of the oscillation induced anomalies in the atmospheric neutrino flux.

A. Lai

A search for the decay $K_S\toπ^0γγ$ has been made using the NA48 detector at the CERN SPS. Using data collected in 1999 during a 40-hour run with a high-intensity $K_S$ beam, an upper limit for the branching ratio $BR(K_S\toπ^0γγ, z\ge 0.2)<3.3\times\nolinebreak 10^{-7}$ has been obtained at 90% confidence level, where $z=m_{γγ}^2/m_{K_0}^2$.

C. Arnaboldi, F. T. Avignone, J. Beeman, M. Barucci

CUORE is a proposed tightly packed array of 1000 TeO2 bolometers, each being a cube 5 cm on a side with a mass of 760 g. The array consists of 25 vertical towers, arranged in a square of 5 towers by 5 towers, each containing 10 layers of 4 crystals. The design of the detector is optimized for ultralow-background searches: for neutrinoless double beta decay o

J. J. Ferrando, J. A. Sáez

We give a classification of the type D spacetimes based on the invariant differential properties of the Weyl principal structure. Our classification is established using tensorial invariants of the Weyl tensor and, consequently, besides its intrinsic nature, it is valid for the whole set of the type D metrics and it applies on both, vacuum and non-vacuum sol

L. Sriramkumar

We consider the response of a uniformly accelerated monopole detector that is coupled to a superposition of an odd and an even power of a quantized, massless scalar field in flat spacetime in arbitrary dimensions. We show that, when the field is assumed to be in the Minkowski vacuum, the response of the detector is characterized by a Bose-Einstein factor in

Chiang-Mei Chen, James M. Nester, Roh-Suan Tung

We first describe a class of spinor-curvature identities (SCI) which have gravitational applications. Then we sketch the topic of gravitational energy-momentum, its connection with Hamiltonian boundary terms and the issues of positivity and (quasi)localization. Using certain SCIs several spinor expressions for the Hamiltonian have been constructed. One SCI l

Nicole Schweikardt

We present a new Ehrenfeucht-Fraisse game approach to collapse results in database theory and we show that, in principle, this approach suffices to prove every natural generic collapse result. Following this approach we can deal with certain infinite databases where previous, highly involved methods fail. We prove the natural generic collapse for Z-embeddabl

Jörg Rothe

In this tutorial, selected topics of cryptology and of computational complexity theory are presented. We give a brief overview of the history and the foundations of classical cryptography, and then move on to modern public-key cryptography. Particular attention is paid to cryptographic protocols and the problem of constructing the key components of such prot

Stefan Ratschan

Exactly solving first-order constraints (i.e., first-order formulas over a certain predefined structure) can be a very hard, or even undecidable problem. In continuous structures like the real numbers it is promising to compute approximate solutions instead of exact ones. However, the quantifiers of the first-order predicate language are an obstacle to allow

B. V. Kryzhanovsky, L. B. Litinskii, A. L. Mikaelyan

The storage capacity of the Hopfield model is about 15% of the network size. It can be increased significantly in the Potts-glass model of the associative memory only. In this model neurons can be in more than two different states. We show that even greater storage capacity can be achieved in the parametrical neural network (PNN) that is based on the paramet

A. J. Wagner, L. M. Wilson, M. E. Cates

We investigate by Lattice Boltzmann methods the effect of inertia on the deformation and break-up of a two-dimensional fluid droplet surrounded by fluid of equal viscosity (in a confined geometry) whose shear rate is increased very slowly. We give evidence that in two dimensions inertia is {\em necessary} for break-up, so that at zero Reynolds number the dro

A. E. Leanhardt, Y. Shin, D. Kielpinski, D. E. Pritchard

Coreless vortices were phase-imprinted in a spinor Bose-Einstein condensate. The three-component order parameter of F=1 sodium condensates held in a Ioffe-Pritchard magnetic trap was manipulated by adiabatically reducing the magnetic bias field along the trap axis to zero. This distributed the condensate population across its three spin states and created a

V. I. Kozub, A. V. Lopatin, V. M. Vinokur

We investigate the Josephson transport through a thin semiconductor barrier containing impurity centers with the on-site Hubbard interaction $u$ of an arbitrary sign and strength. We find that in the case of the repulsive interaction the Josephson current changes sign with the temperature increase if the energy of the impurity level $ε$ (measured from the Fe

M. B. Walker, C. Detlefs

This article describes a model in which ferromagnetism necessarily accompanies a spin-density-wave lockin transition in the borocarbide structure provided the commensurate phase wave vector satisfies Q = (m/n)a* with m even and n odd. The results account for the magnetic properties of TbNi2B2C, and are also possibly relevant also for those of ErNi2B2C.

Ko Okumura

We present an intuitive physical picture for fractures in nacre-type stratified materials via scaling arguments: strain distributions around a fracture are rather different depending on directions and size of fractures. We thus observe that viscoelastic effects are important for parallel fractures. These effect are taken into account via the simplest viscoel

T. Brandes, J. Robinson

We discuss electron scattering in a one-dimensional delta barrier potential with either time-dependent coupling constant (classical model) or a coupling constant that is linear in a boson coordinate (quantum model). We find an exact continued fraction solution and Fano like resonances in the transmission coefficient. In the quantum model, energies for perfec

Dennis P. Clougherty

A theoretical analysis of the ground state of long-chain (K@C$_{60}$)$_n$ is presented. Within mean field theory, a ferroelectric ground state is found to be stable because of the pseudo-Jahn-Teller mixing of the b$_{1u}$ and the b$_{2g}$ band with a zone-center optical phonon involving the displacement of the endohedral K^+ ions. A phase diagram for this mo

Mario Castro

We consider the problem of heterogeneous nucleation and growth. The system is described by a phase field model in which the temperature is included through thermal noise. We show that this phase field approach is suitable to describe homogeneous as well as heterogeneous nucleation starting from several general hypotheses. Thus we can investigate the influenc

N. Karchev

The magnon exchange mechanism of ferromagnetic superconductivity (FM-superconductivity) was developed to explain in a natural way the fact that the superconductivity in $UGe_2$, $ZrZn_2$ and $URhGe$ is confined to the ferromagnetic phase.The order parameter is a spin anti-parallel component of a spin-1 triplet with zero spin projection. The transverse spin f

J. P. Huang, K. W. Yu, G. Q. Gu, Mikko Karttunen

Biological cells can be treated as composites of graded material inclusions. In addition to biomaterials, graded composites are important in more traditional materials science. In this article, we investigate the electrorotation (ER) spectrum of a graded colloidal suspension in an attempt to discuss its dielectric properties. For that, we use the recently ob

Tribikram Gupta, D. M. Gaitonde

We calculate the low temperature longitudinal ultrasonic attenuation rate $α_S$ in clean d-wave superconductors. We consider the contribution of previously ignored processes involving the excitation of a pair of quasi-holes or quasi-particles. These processes, which are forbidden by energy conservation in conventional s-wave superconductors, have a finite ph

J. H. G. Owen, K. Miki, D. R. Bowler

Heteroepitaxial strain can be a controlling factor in the lateral dimensions of 1-D nanostructures. Bi nanolines on Si(001) have an atomic structure which involves a large sub-surface reconstruction, resulting in a strong elastic coupling to the surrounding silicon. We present variable-bias STM and first principles electronic structure calculations of the Bi

Frank O. Pfeiffer, Heiko Rieger

We study loop percolation models in two and in three space dimensions, in which configurations of occupied bonds are forced to form closed loop. We show that the uncorrelated occupation of elementary plaquettes of the square and the simple cubic lattice by elementary loops leads to a percolation transition that is in the same universality class as the conven

G. E. Astrakharchik, S. Giorgini

The ground-state correlation properties of a one-dimensional Bose system described by the Lieb-Liniger Hamiltonian are investigated by using exact quantum Monte Carlo techniques. The pair distribution function, static structure factor, one-body density matrix and momentum distribution of a homogeneous system are calculated for different values of the gas par

B. Placais, N. Lutke-Entrup, J. Bellessa, P. Mathieu

The peak effect has been investigated in clean Nb crystals with artificially corrugated surfaces by measuring the linear surface impedance in the 1kHz-1MHz frequency range. From a two-mode analysis of the complex spectra, we establish that vortex dynamics is governed by surface pinning and deduce the associated vortex slippage length. We demonstrate experime

E. Pazy

Pure dephasing of an exciton in a small quantum dot by optical and acoustic phonons is calculated using the ``independent boson model&#39;&#39;. Considering the case of zero temperature the dephasing is shown to be only partial which manifests itself in the polarization decaying to a finite value. Typical dephasing times can be assigned even though the spect

W. Götze, Th. Voigtmann

Within the mode-coupling theory for idealized glass transitions, we study the evolution of structural relaxation in binary mixtures of hard spheres with size ratios $δ$ of the two components varying between 0.5 and 1.0. We find two scenarios for the glassy dynamics. For small size disparity, the mixing yields a slight extension of the glass regime. For large

Sergei Sergeenkov

Within a 2D model of Josephson junction arrays (created by 2D network of twin boundary dislocations with strain fields acting as insulating barrier between hole-rich domains in underdoped crystals), a few novel effects expected to occur in intrinsically granular material are predicted including: (i) Josephson chemomagnetism (chemically induced magnetic momen

Joseph Snider, Clare C. Yu

We show that anomalous diffusion can result when the steps of a random walk are not statistically independent. We present an algorithm that counts all the possible paths of particles diffusing on random graphs with arbitrary degree distribution. Using this to calculate the mean square displacement, we show that in sharp contrast to continua, random walks on

T. Maehira, T. Hotta, K. Ueda, A. Hasegawa

In order to investigate electronic properties of recently discovered heavy fermion superconductors CeTIn$_5$ (T=Ir and Co), we employ the relativistic linear augmented-plane-wave (RLAPW) method to clarify the energy band structures and Fermi surfaces of those materials. The obtained energy bands mainly due to the large hybridization between Ce $4f$ and In 5$

Mikko Mottonen, Naoki Matsumoto, Mikio Nakahara, Tetsuo Ohmi

It is shown that a vortex can be continuously created in a Bose-Einstein condensate with hyperfine spin F=2 in a Ioffe-Pritchard trap by reversing the axial magnetic field adiabatically. It may be speculated that the condensate cannot be confined in the trap since the weak-field seeking state makes transitions to the neutral and the strong-field seeking stat

J. S. Alcaniz, J. M. F. Maia

We investigate observational constraints from present and future supernova data on a large class of decaying vacuum cosmologies. In such scenarios the present value of the vacuum energy density is quantified by a positive $β$ parameter smaller than unity. By assuming a Gaussian prior on the matter density parameter ($Ω_{\rm{m}} = 0.35 \pm 0.07$) we find $Ω_{

Dan Hooper, Brenda Dingus

Using the EGRET data and an improved point source analysis, including an energy dependent point spread function and an unbinned maximum likelihood technique, we have been able to place considerably lower limits on the gamma ray flux from the galactic center region. We also test this method on known sources, the Crab and Vela pulsars. In both cases, we find t

J. B. Hutchings

2 micron broad- and narrow-band imaging with the Gemini-N telescope of five z~4.7 QSOs, has resolved both the host galaxies and [O II] emission-line gas. The resolved fluxes of the host galaxies fall within the extrapolated spread of the K-z relationship for radio galaxies at lower redshifts, and their resolved morphology is irregular. The [O II] images indi

Tania Regimbau, Jose Antonio de Freitas Pacheco

We use recent population synthesis results to investigate the distribution of pulsars in the frequency space, having a gravitational strain high enough to be detected by the future generations of laser beam interferometers. We find that until detectors become able to recover the entire population, the frequency distribution of the &#39;detectable&#39; popula

A. Goldwurm

In the last decade our knowledge on galactic black hole systems and in particular on their high energy behavior has considerably improved. I will briefly review here the main results obtained by the high-energy missions SIGMA/GRANAT, Compton-GRO, Beppo-SAX and Rossi-XTE, on these objects and, in particular, I will discuss the spectral shapes observed at ener

E. N. Alexeyev, L. N. Alexeyeva

The results of twenty-year-long Galactic observations in neutrino radiation are summarized. Except for the recording of a neutrino signal from the supernova SN 1987A, no Galactic bursts of collapse neutrinos have been detected. An upper bound on the mean frequency of gravitational collapses in our Galaxy was obtained, $f_{collapse} (90% {confidence}) < 0.13

W. Pietsch

First results of X-ray source population studies in nearby galaxies show the potential of XMM-Newton observations. I will report on first XMM-Newton M31 results and on three of our XMM-Newton projects, an X-ray source population study in the Magellanic Clouds (MCs), a deep raster survey of M33, and an investigation of the hot interstellar medium (ISM) in the

E. G. Jilinski, V. N. Frolov, J. K. Ananjevskaja, J. Straume

The results of astrometric and photometric investigations of the open cluster NGC 7243 are presented. Proper motions of 2165 stars with root-mean-square error of 1.1 mas/yr were obtained by means of PDS scanning of astrometric plates covering the time interval of 97 years. A total of 211 cluster members down to V=15.5 mag have been identified. V and B magnit

U. Heber, P. F. L. Maxted, T. R. Marsh, C. Knigge

Subdwarf B (sdB) stars form the blue end of the horizonal branch. Their peculiar atmospheric abundance patterns are due to diffusion processes. However, diffusion models fail to explain these anomalies quantitatively. From a NLTE model atmosphere analysis of 40 sdB stars, we found that the more luminous (i.e. more evolved) stars have anomalous H alpha and He

Philippe Andre, Jeroen Bouwman, Arnaud Belloche, Patrick Hennebelle

Improving our understanding of the initial conditions and earliest stages of protostellar collapse is crucial to gain insight into the origin of stellar masses, multiple systems, and protoplanetary disks. Observationally, there are two complementary approaches to this problem: (1) studying the structure and kinematics of prestellar cores observed prior to pr

E. Simon, L. Berge, A. Broniatowski, R. Bouvier

SICANE is a neutron scattering multidetector facility for the determination of the quenching factor (ratio of the response to nuclear recoils and to electrons) of cryogenic detectors used in direct WIMP searches. Well collimated monoenergetic neutron beams are obtained with inverse (p,n) reactions. The facility is described, and results obtained for the quen

H. Schulz, C. Henkel

Optical emission-line profiles were evaluated in order to explore the structure of galactic nuclei containing H2O megamaser sources. Galactic rotation and outflow of narrow-line gas are common features of this sample of water megamaser galaxies. All decomposed line-systems exhibit AGN typical line ratios. Recent detections of H2O megamasers in starburst gala

S. Falter, U. Heber, S. Dreizler, S. L. Schuh

The recently discovered new class of sdB pulsators (sdBV) offers a powerful possibility for the investigation of their interior and thus their evolutionary history. The first step towards applying asteroseismologic tools is the identification of pulsation modes. We reoport on simultaneous spectroscopic and multi-band photometric time series observations of P

U. Heber, P. F. L. Maxted, T. R. Marsh, C. Knigge

Subdwarf B (sdB) stars form the blue end of the horizonal branch (EHB). Their peculiar atmospheric abundance patterns are due to diffusion processes. However, diffusion models fail to explain these anomalies quantitatively. Weak mass loss has been invoked to solve these discrepancies, but up to now has not been observed. We report first observational evidenc

R. -D. Scholz, M. J. McCaughrean, N. Lodieu, B. Kuhlbrodt

We have identified a new early T dwarf only 3.6pc from the Sun, as a common proper motion companion (separation 1459AU) to the K5V star Epsilon Indi (HD209100). As such, Epsilon Indi B is one of the highest proper motion sources outside the solar system (~4.7 arcsec/yr), part of one of the twenty nearest stellar systems, and the nearest brown dwarf to the Su

R. A. Laing, J. R. Canvin, A. H. Bridle

We model jets in low-luminosity (FR I) radio galaxies as intrinsically symmetrical, axisymmetric, decelerating relativistic flows with transverse velocity gradients. This allows us to derive velocity fields and the three-dimensional distributions of magnetic-field ordering and rest-frame emissivity. A conservation-law analysis, combining the kinematic model

B. Fuchs

I discuss anew how arguments about the internal dynamics of galactic disks set constraints on the otherwise ambiguous decomposition of the rotation curves of spiral galaxies into the contributions by the various constituents of the galaxies. Analyzing the two sample galaxies NGC 3198 and NGC 2985 I conclude from the multiplicities of the spiral arms and the

Marcelo Borges Fernandes, H. J. G. L. M. Lamers, Michaela Kraus

The spectra of stars with the B[e] phenomenon are dominated by features that are related to physical conditions of circumstellar material around these objects and are not intrinsic to the stars. Previous studies have shown that emission lines present in the optical spectra of these objects are formed in an equatorial rotating disk. The analysis of high and l

I. Bednarek, A. Brzezina, R. Manka, M. Zastawny-Kubica

In this paper a theoretical model of a magnetic white dwarf is studied. All numerical calculations are performed under the assumption of a spherically symmetric star. The obtained equation of state is stiffer for the increasing value of magnetic field B. The numerical values of the maximum mass and radius are presented. Sensibility of the results to the choi

David Peat, Raymond Butler

Stromgren indices v and b are combined with broad-band index I, and a new index p, the short wavelength half of the v band, to estimate CN 4215A molecular absorption in a sample of stars in M22. The results have been used to estimate carbon and nitrogen abundances and suggest groups of stars within this cluster, each with a characteristic nitrogen abundance,

A. Haungs

Primary cosmic ray particles above energies of about 100 TeV are investigated by large-area ground based detector installations, observing various components of the development of extensive air-showers (EAS). By such an indirect access to the primary cosmic ray spectrum a steepening of the power-law falls off at around 3-5 PeV, known as the {\em knee} has be

U. Heber

Subluminous B (sdB) stars can result from stable Roche lobe overflow or common envelope ejection in close binary systems. The companions are either low mass main sequence stars or white dwarfs. We discuss mass determinations for sdB stars from such systems and report the discovery of the bright nearby sdB star, HD 188112, to be a close binary system of unusu

Marcelo Borges Fernandes, Francisco X. de Araújo, H. J. G. L. M. Lamers

The spectra of stars with the B[e] phenomenon are dominated by features that are related to physical conditions of circumstellar material around these objects and are not intrinsic to the stars. Because of this, they form a very heterogeneous group. This group contains objects with different evolutionary stages. Lamers et al. (1998) have suggested a new desi

Seathrun O&#39;Tuairisg, Raymond Butler, Andy Shearer, Michael Redfern

A two-week campaign of high-resolution imaging of the centre of M15 using the tip/tilt correcting TRIFFID-2 camera, followed by analysis with ISIS (image matching & subtraction software), has produced the most sensitive survey to date of variable stars in the central ~1x1 arcmin^2 - a total of 48 were detected -, and constrains the size of the dwarf nova pop

F. K. Liu, Y. H. Zhang

A catalogue of extra-galactic jets is very useful both in observational and theoretical studies of active galaxies. With the use of new powerful radio instruments, the detailed structures of very compact or weak radio sources are investigated observationally and many new radio jets are detected. In this paper, we give a list of 661 radio sources with detecte

I. M. Brancus, H. Rebel, A. F. Badea, A. Haungs

In view of the current efforts to extend the KASCADE experiment (KASCADE-Grande) for observations of Extensive Air Showers (EAS) of primary energies up to 1 EeV, the features of muon arrival time distributions and their correlations with other observable EAS quantities have been scrutinised on basis of high-energy EAS, simulated with the Monte Carlo code COR

F. K. Liu, Xue-Bing Wu

Recent intensive observations of the BL Lac object OJ 287 raise a lot of questions on the models of binary black holes, processing jets, rotating helical jets and thermal instability of slim accretion disks. After carefully analyzing their radio flux and polarization data, Valtaoja et al. (\cite{valtaoja00}) propose a new binary model. Based on the black hol

F. Vagnetti, D. Trevese

Optical spectral variability of quasars and BL Lac Objects is compared by means of the spectral variability parameter beta (Trevese & Vagnetti 2002). Both kinds of objects change their spectral slopes alpha, becoming bluer when brighter, but BL Lac Objects have smaller beta values and are clearly separated from quasars in the alpha-beta plane. Models account

Otmar Stahl, Thomas Gaeng, Chris Sterken, Andreas Kaufer

We have spectroscopically monitored the galactic Luminous Blue Variable HD 160529 and obtained an extensive high-resolution data set that covers the years 1991 to 2002. During this period, the star evolved from an extended photometric minimum phase towards a new visual maximum. In several observing seasons, we covered up to four months with almost daily spec

W. R. F. Dent, R. S. Furuya, C. J. Davis

We present results from a study of molecular gas and dust in the vicinity of the Herbig Haro object HH2. Emission from the sub-mm continuum, 12CO and HCO+ was mapped with angular resolutions ranging from 14 arcsec to 5 arcsec (or 0.01pc at the distance of HH2). The continuum shows an extended dust clump of mass 3.8Msun and temperature 22K, located downstream

R. Aurich, F. Steiner

Quintessence models leading to a constant equation of state are studied in hyperbolic universes. General properties of the quintessence potentials V(phi) are discussed, and for some special cases also the exact analytic expressions for these potentials are derived. It is shown that the observed angular power spectrum of the cosmic microwave background (CMB)

T. Venturi, D. Dallacasa

We will present a multiepoch study of the three blazars 0954+658 (BL--Lac), PKS1510--089 (HPQ) and 1749+096 (BL--Lac). The first two sources are known to be $γ$--ray loud. Our study is based on milliarcsecond resolution polarimetric observations carried out with the VLBA at 8.4 GHz. The observations took place between January 1999 and May 2001. Superluminal

A. Heger, C. L. Fryer, S. E. Woosley, N. Langer

How massive stars die -- what sort of explosion and remnant each produces -- depends chiefly on the masses of their helium cores and hydrogen envelopes at death. For single stars, stellar winds are the only means of mass loss, and these are chiefly a function of the metallicity of the star. We discuss how metallicity, and a simplified prescription for its ef

Christopher J. Conselice

A major goal of contemporary astrophysics is understanding the origin of the most massive galaxies in the universe, particularly nearby ellipticals and spirals. Theoretical models of galaxy formation have existed for many decades, although low and high redshift observations are only beginning to put constraints on different ideas. We briefly describe these o

R. Quadri, O. Moeller, P. Natarajan

We study the observational signatures of the lensing signal produced by dark matter halos with embedded misaligned disks. This issue is of particular interest at the present time since most of the observed multiple lens systems have magnification ratios and image geometries that are not well-fit by standard mass models. The presence of substructure exterior

J. C. Lopez Vieyra, A. V. Turbiner

A detailed quantitative analysis of the system $(ppe)$ placed in magnetic field ranging from $0 - 4.414 \times 10^{13} G$ is presented. The present study is focused on the question of the existence of the molecular ion $H_2^{+}$ in a magnetic field. As a tool, a variational method with an optimization of the form of the vector potential (optimal gauge fixing

C. M. Cantalupo, A. K. Romer, J. B. Peterson, P. Gomez

We present a 40GHz (7.5 mm) raster scan image of a 3.6x2 degree region centered on the low redshift (z=0.055) cluster of galaxies Abell 3667. The cluster was observed during the Antarctic winter of 1999 using the Corona instrument (15.7&#39; FWHM beam) on the Viper Telescope at the South Pole. The Corona image of A3667 is one of the first direct (i.e. rather

Marco Frasca

It is shown that a macroscopic superposition state of radiation, strongly interacting with an ensemble of two-level atoms, is removed generating a coherent state describing a classical radiation field, when the thermodynamic limit is taken on the unitary evolution obtained by the Schroedinger equation. Decoherence appears as a dynamical effect in agreement w

L. Tewordt, D. Fay

The specific heat coefficient gamma_s(H) and the electronic thermal conductivity kappa_{es}(H) are calculated for Abrikosov&#39;s vortex lattice by taking into account the effects of supercurrent flow and Andreev scattering. First we solve the gap equation for the entire range of magnetic fields. We take into account vertex corrections due to impurity scatte

Johnpierre Paglione, M. A. Tanatar, D. G. Hawthorn, Etienne Boaknin

The resistivity of the heavy-fermion superconductor CeCoIn5 was measured as a function of temperature, down to 25 mK and in magnetic fields of up to 16 T applied perpendicular to the basal plane. With increasing field, we observe a suppression of the non-Fermi liquid behavior, rho ~ T, and the development of a Fermi liquid state, with its characteristic rho

Alice M. Crawford, Nicolas Mordant, Andy M. Reynolds, Eberhard Bodenschatz

In a recent letter, Christian Beck described a theoretical link between a family of stochastic differential equations and the probability density functions (PDF) derived from the formalism of nonextensive statistical mechanics. He applied the theory to explain experimentally measured PDFs from fully developed fluid turbulence. Here we present new experimenta

Makoto Katori, Naoaki Komatsuda

A system of Brownian motions in one-dimension all started from the origin and conditioned never to collide with each other in a given finite time-interval $(0, T]$ is studied. The spatial distribution of such vicious walkers can be described by using the repulsive eigenvalue-statistics of random Hermitian matrices and it was shown that the present vicious wa

Rennan Barkana

Motivated by the recent direct detection of cosmological gas infall, we develop an analytical model for calculating the mean density profile around an initial overdensity that later forms a dark matter halo. We account for the problem of peaks within peaks; when considering a halo of a given mass we ensure that this halo is not a part of a larger virialized

Marco Matone

We show that a suitable rescaling of the matrix model coupling constant makes manifest the duality group of the N=2 SYM theory with gauge group SU(2). This is done by first identifying the possible modifications of the SYM moduli preserving the monodromy group. Then we show that in matrix models there is a simple rescaling of the pair $(S_D,S)$ which makes t

Iosif Bena, Calin Ciocarlie

We construct several classes of exact supersymmetric supergravity solutions describing D4 branes polarized into NS5 branes and F-strings polarized into D2 branes. These setups belong to the same universality class as the perturbative solutions used by Polchinski and Strassler to describe the string dual of N=1* theories. The D4-NS5 setup can be interpreted a

Christopher W. O&#39;Dell, Brian G. Keating, Angelica de Oliveira-Costa, Max Tegmark

The coming flood of CMB polarization experiments, spurred by the recent detection of CMB polarization by DASI and WMAP, will be confronted by many new analysis tasks specific to polarization. For the analysis of CMB polarization data sets, the devil is truly in the details. With this in mind, we present the details of the data analysis for the POLAR experime

G. J. Galloway, S. Surya, E. Woolgar

Assuming certain asymptotic conditions, we prove a general theorem on the non-existence of static regular (i.e., nondegenerate) black holes in spacetimes with a negative cosmological constant, given that the fundamental group of space is infinite. We use this to rule out the existence of regular negative mass AdS black holes with Ricci flat scri. For any mas

Tobias Hurth

We give a status report on inclusive rare B decays, highlighting recent developments and open problems. We focus on the decay modes $B \to X_{s,d} γ$, $ B \to X_s \ell^+\ell^-$ and $B \to X_s ν\bar ν$ and on their role in the search for new physics. Most of the inclusive rare B decays are important modes of flavour physics due to the small hadronic uncertain

A. Vezzani

We give a rigorous proof of the existence of spontaneous magnetization at finite temperature for the Ising spin model defined on the Sierpinski carpet fractal. The theorem is inspired by the classical Peierls argument for the two dimensional lattice. Therefore, this exact result proves the existence of spontaneous magnetization for the Ising model in low dim

Victor Ginzburg, Dmitry Kaledin

We establish a connection between smooth symplectic resolutions and symplectic deformations of a (possibly singular) affine Poisson variety. In particular, let V be a finite-dimensional complex symplectic vector space and G\subset Sp(V) a finite subgroup. Our main result says that the so-called Calogero-Moser deformation of the orbifold V/G is, in an appropr

Angelica de Oliveira-Costa, Max Tegmark, Chris O&#39;Dell, Brian Keating

The DASI discovery of CMB polarization has opened a new chapter in cosmology. Most of the useful information about inflationary gravitational waves and reionization is on large angular scales where Galactic foreground contamination is the worst, so a key challenge is to model, quantify and remove polarized foregrounds. We use the POLAR experiment, COBE/DMR a

H. Davoudiasl, J. L. Hewett, T. G. Rizzo

We examine the effects of boundary kinetic terms in the Randall-Sundrum model with gauge fields in the bulk. We derive the resulting gauge Kaluza-Klein (KK) state wavefunctions and their corresponding masses, as well as the KK gauge field couplings to boundary fermions, and find that they are modified in the presence of the boundary terms. In particular, for