February 2003 arXiv papers — page 12

H. J. Buttery, G. Cotter, R. W. Hunstead, E. M. Sadler

Statistical overdensities of radiosources in the Sydney University Molonglo Sky Survey (SUMSS) are used as signposts to identify high-redshift clusters of galaxies. These potential clusters have been observed at 20 and 13 cm at the Australia Telescope Compact Array (ATCA) to obtain better positional accuracy for the sources. A subsample have been imaged in V

Hiroshi Imai, Katsunori M. Shibata, Kevin B. Marvel, Philip J. Diamond

We report observations of water masers around the semiregular variable RT Virginis (RT Vir), which have been made with the Very Long Baseline Array (VLBA) of the National Radio Astronomy Observatory (NRAO) at five epochs, each separated by three weeks of time. We detected about 60 maser features at each epoch. Overall, 61 features, detected at least twice, w

P. G. Willemsen, C. A. L. Bailer-Jones, T. A. Kaempf, K. S. deBoer

We have assessed how well stellar parameters (T_eff, logg and [Fe/H]) can be retrieved from low-resolution dispersed images to be obtained by the DIVA satellite. Although DIVA is primarily an all-sky astrometric mission, it will also obtain spectrophotometric information for about 13 million stars (operational limiting magnitude V ~ 13.5 mag). Constructional

G. A. Drukier, C. D. Bailyn, W. F. Van Altena, T. M. Girard

We present proper motions derived from WFPC2 imaging for stars in the core of the peculiar globular cluster NGC 6752. The central velocity dispersion in both components of the proper motion is 12 km/s. We discuss the implications of this result as well as the intrinsic difficulties in making such measurements. We also give an alternative correction for the 3

C. Loup, N. Delmotte, D. Egret, M. -R. Cioni

We have been recently faced with the problem of cross--identifying stars recorded in historical catalogues with those extracted from recent fully digitized surveys (such as DENIS and 2MASS). Positions mentioned in the old catalogues are frequently of poor precision, but are generally accompanied by finding charts where the interesting objects are flagged. Th

Noam Soker, Laurence P. David

We examine recent developments in the cluster cooling flow scenario following recent observations by Chandra and XMM-Newton. We show that the distribution of gas emissivity verses temperature determined by XMM-Newton gratings observations demonstrates that the central gas in cooling flow clusters cannot be in simple steady-state. Combining this result with t

Andreas Rieschick, Gerhard Hensler

Here we investigate an exemplary chemodynamical evolutionary simulation of a dwarf irregular galaxy. By means of this model we demonstrate the existence of three gas mixing cycles: 1) An inner "local cycle" mixing the metals produced in stars locally, and 2) an outer "galactic cycle" on which hot gas is driven out of the galaxy by multiple su

A. Iovino, R. de Carvalho, R. Gal, S. Odewahn

We have identified eighty-four small, high density groups of galaxies out to z ~ 0.2 in a region of ~ 2000 square degrees around the north galactic pole using DPOSS (the Digitized Second Palomar Observatory Sky Survey). The groups have at least four galaxies satisfying more stringent criteria than those used by Hickson in his pioneering work in 1982: the ado

Noam Soker

I use a simple analytical model to show that simple heat conduction models cannot significantly suppress cluster cooling flows. I build a static medium where heat conduction globally balances radiative cooling, and then perturb it. I show that a perturbation extending over a large fraction of the cooling flow region will grow to the non-linear regime within

A. D. Erlykin, A. W. Wolfendale

Some six years ago, we (Erlykin and Wolfendale, 1997) proposed the `single source model' in which a local, recent supernova remnant (SNR) was responsible for the `knee' in the cosmic ray (CR) energy spectrum at ~3PeV. Stimulated by the paper by Bhadra (2002), which drew attention to a possible gamma ray signature of this local remnant, we now study t

A. Olech

The results of the CCD observations of the 2002 superoutburst of V1141 Aql are described. We have detected clear superhumps characterized by the period of 0.05930(5) days. There was another, much weaker, modulation in the light curve of V1141 Aql. Its amplitude is equal to $0.012\pm0.002$ mag and its period to 0.03923(8) days. We have also discovered quasi p

V. Suleimanov, F. Meyer, E. Meyer-Hofmeister

Detailed analysis of the lightcurve of CAL 87 clearly has shown that the high optical luminosity comes from the accretion disc rim and can only be explained by a severe thickening of the disc rim near the location where the accretion stream impinges. This area is irradiated by the X-rays where it faces the white dwarf. Only if the reprocessing rate of X-rays

Marcella Contini, Thierry Contini

We investigate the properties of dust and dust-to-gas ratios in different starburst regions of luminous infrared galaxies (LIGs). We refer to the sample of seven LIGs recently observed in the mid-infrared by Soifer et al. (2001) using the Keck telescopes with spatial resolution approaching the diffraction limit. These seven objects are among the closest LIGs

Matteo Murgia

This paper deals with the spectral ageing study of a representative sample of compact symmetric objects (CSOs) and compact steep spectrum (CSS) sources. Observations reveal a distinctive high-frequency steepening of the radio spectra of many of these sources. The existence of such a spectral feature is expected or may be naturally interpreted in terms of rad

I. Georgantopoulos, A. Georgakakis, G. C. Stewart, A. Akylas

We present XMM-Newton observations of AXJ0341.4-4453, a mildly reddened A_V<7 QSO at a redshift of z=0.672. The XMM-Newton spectrum shows a large obscuring column N_H~10^23 cm^{-2} corresponding to A_V~70, in agreement with previous results based on the lower limit of the ASCA hardness ratio. The X-ray spectrum is represented by a &#39;scattering&#39; model

H. J. de Vega, N. Sanchez

We present an overview on extreme energy cosmic rays (EECR) and the fundamental physics connected with them. The top-down and bottom-up scenarii are contrasted. We summarize the essential features underlying the top-down scenarii for EECR, namely, the lifetime and the mass {\bf imposed} to the heavy relics whatever they be: topological and non-topological so

Y. Jack Ng, W. A. Christiansen, H. van Dam

At Planck-scale, spacetime is &#34;foamy&#34; due to quantum fluctuations predicted by quantum gravity. Here we consider the possibility of using spacetime foam-induced phase incoherence of light from distant galaxies and gamma-ray bursters to probe Planck-scale physics. In particular, we examine the cumulative effects of spacetime fluctuations over a huge d

P. A. Grassi, G. Policastro, P. van Nieuwenhuizen

We give an introduction to a new approach to the covariant quantization of superstrings. After a brief review of the classical Green--Schwarz superstring and Berkovits&#39; approach to its quantization based on pure spinors, we discuss our covariant formulation without pure spinor constraints. We discuss the relation between the concept of grading, which we

Martin White

We use mock Sunyaev-Zel&#39;dovich effect (SZE) maps to investigate how well the Planck mission might find and characterize clusters of galaxies. We discuss different combinations of frequency maps and different methods for identifying cluster candidates. The resulting catalogues are not complete even for relatively high mass thresholds, but the full sky nat

D. L. Kaplan, S. R. Kulkarni, M. H. van Kerkwijk

We have detected the optical counterpart to the nearby isolated neutron star RX J1605.3+3249 using observations from the Space Telescope Imaging Spectrometer aboard the Hubble Space Telescope. The counterpart, with m_{50CCD}=26.84+/-0.07 mag and very blue colors, lies close to the ROSAT HRI error circle and within the Chandra error circle. The spectrum is co

Steven C. Pieper

I show that it does not seem possible to change modern nuclear Hamiltonians to bind a tetraneutron without destroying many other successful predictions of those Hamiltonians. This means that, should a recent experimental claim of a bound tetraneutron be confirmed, our understanding of nuclear forces will have to be significantly changed. I also point out som

M. Juvela, P. Padoan, R. Jimenez

The photoelectric heating is believed to be the main heating mechanism in cool HI clouds. The heating rate can be estimated through observations of the [CII] line emission, since this is the main coolant in regions where the photoelectric effect dominates the heating. Comparison of the [CII] emission with the far-infrared (FIR) emission allows to constrain t

Peter Arnold, Guy D. Moore, Laurence G. Yaffe

Results are presented of a full leading-order evaluation of the shear viscosity, flavor diffusion constants, and electrical conductivity in high temperature QCD and QED. The presence of Coulomb logarithms associated with gauge interactions imply that the leading-order results for transport coefficients may themselves be expanded in an infinite series in powe

V. Barger, Hye-Sung Lee, Danny Marfatia

We assay how inflationary models whose properties are dominated by the dynamics of a single scalar field are constrained by cosmic microwave background (CMB) data from the Wilkinson Microwave Anisotropy Probe (WMAP). We classify inflationary models in a plane defined by the horizon-flow parameters. Our approach differs from that of the WMAP collaboration in

L. W. Lee, A. P. Young

Results of Monte Carlo simulations of XY and Heisenberg spin glass models in three dimensions are presented. A finite size scaling analysis of the correlation length of the spins and chiralities of both models shows that there is a single, finite-temperature transition at which both spins and chiralities order.

L. Cornalba, M. S. Costa

We analyze the classical stability of string cosmologies driven by the dynamics of orientifold planes. These models are related to time-dependent orbifolds, and resolve the orbifold singularities which are otherwise problematic by introducing orientifold planes. In particular, we show that the instability discussed by Horowitz and Polchinski for pure orbifol

Yousaf Butt, Paula Benaglia, Jorge Combi, Michael Corcoran

The HEGRA Cherenkov telescope array group recently reported a steady and extended unidentified TeV gamma-ray source lying at the outskirts of Cygnus OB2. This is the most massive stellar association known in the Galaxy, estimated to contain ~2600 OB type members alone. It has been previously argued that the large scale shocks and turbulence induced by the mu

I. Horvath, S. J. Dong, T. Draper, F. X. Lee

While sign-coherent 4-dimensional structures cannot dominate topological charge fluctuations in the QCD vacuum at all scales due to reflection positivity, it is possible that enhanced coherence exists over extended space-time regions of lower dimension. Using the overlap Dirac operator to calculate topological charge density, we present evidence for such str

K. Hamaguchi, Nobuhito Maru

We discuss nonanomalous R-symmetry in the supersymmetric grand unified theories. In particular, we explore anomaly-free solutions predicting the gravitino mass in the range of $10^{-3} eV \lsim m_{3/2} \lsim 1 TeV$ when the $μ$-parameter is fixed to be $μ\simeq 1 TeV$. In the minimal SU(5) GUT, we have shown that $μ\simeq 1 TeV$ is obtained only if the gravi

M. Kachelriess, D. V. Semikoz, M. A. Tortola

Ultra-high energy cosmic ray (UHECR) protons produced by uniformly distributed astrophysical sources contradict the energy spectrum measured by both the AGASA and HiRes experiments, assuming the small scale clustering of UHECR observed by AGASA is caused by point-like sources. In that case, the small number of sources leads to a sharp exponential cutoff at t

Partha Ghose, Manoj K. Samal, Animesh Datta

We show analytically that the {\it Zitterbewegung} and Klein Paradox, such well known aspects of the Dirac Equation are not found in the case of Bosons. We use the Kemmer-Duffin-Harish Chandra formalism with $β$ matrices to arrive at our results

Suzanne M. Linder, Roland Gunesch, Jonathan I. Davies, Maarten Baes

Some Lyman continuum photons are likely to escape from most galaxies, and these can play an important role in ionizing gas around and between galaxies, including gas that gives rise to Lyman alpha absorption. Thus the gas surrounding galaxies and in the intergalactic medium will be exposed to varying amounts of ionizing radiation depending upon the distances

Jian-Jun Yang, Ivan Schmidt

There is a striking suppression of the cross section for production of octet baryons in $e^+ e ^-$ annihilation, as the mass of the produced hadron increases. We present a simple parametrization for the fragmentation functions into octet baryons guided by two input models: the SU(3) flavor symmetry part is given by a quark-diquark model, and the baryon mass

F. Rosati

The presence of a dynamical scalar field in the early universe could significantly affect the `freeze-out&#39; time of particle species. In particular, it was recently shown that an enhancement of the relic abundance of neutralinos can be produced in this way. We examine under which conditions this primordial scalar field could be identified with the Quintes

R. G. Vishwakarma

The current observations are usually explained by an accelerating expansion of the present universe. However, with the present quality of the supernovae Ia data, the allowed parameter space is wide enough to accommodate the decelerating models as well. This is shown by considering a particular example of the dark energy equation-of-state $w_ϕ\equiv p_ϕ/ρ_ϕ=-

M. -Z. Wang

We report the first observation of the charmless hyperonic B decay, B0 -> p Lambdabar pi-, using a 78 fb^-1 data sample recorded on the Upsilon(4S) resonance with the Belle detector at KEKB. The measured branching fraction is B(B0 -> p Lambdabar pi-) = (3.97 ^{+1.00}_{-0.80} +- 0.56) * 10^-6. Searches for B0 -> p Lambdabar K- and p Sigmabar0 pi- yield no sig

Ian G. Moss, Wade Naylor, Wenceslao Santiago-Germán, Misao Sasaki

We investigate some issues regarding quantum corrections for de Sitter branes in a bulk AdS(5) spacetime. The one-loop effective action for a Majorana spinor field is evaluated and compared with the scalar field result. We also evaluate the cocycle function for various boundary conditions, finding that the quantum corrections naturally induce higher order cu

A. Luukanen, K. M. Kinnunen, A. K. Nuottajärvi, H. F. C. Hoevers

In order to investigate the origin of the until now unaccounted excess noise and to minimize the uncontrollable phenomena at the transition in X-ray microcalorimeters we have developed superconducting transition-edge sensors into an edgeless geometry, the so-called Corbino disk (CorTES), with superconducting contacts in the centre and at the outer perimeter.

E. Ben-Haim, Ph. Bambade, P. Roudeau, A. Savoy-Navarro

Using recent measurements of the b-quark fragmentation distribution obtained in $e^+e^- \to b \bar{b}$ events registered at the Z pole, the non-perturbative QCD component of the distribution has been extracted independently of any hadronic physics modelling. This distribution depends only on the way the perturbative QCD component has been defined. When the p

Naohito Nakazawa

The stochastic quantization method is applied to N = 1 supersymmetric Yang-Mills theory, in particular in 4 and 10 dimensions. In the 4 dimensional case, based on Ito calculus, the Langevin equation is formulated in terms of the superfield formalism. The stochastic process manifestly preserves both the global N = 1 supersymmetry and the local gauge symmetry.

Nobuyoshi Ohta

We find a new class of time-dependent brane solutions in supergravities in arbitrary dimensions $D$. These are general intersecting light-like branes (null-branes), and their superposition and intersection rules are obtained. This is achieved by directly solving bosonic field equations for supergravity coupled to a dilaton and antisymmetric tensor fields. We

T. Rauscher, C. Froehlich, K. H. Guber

Explosive nuclear burning in astrophysical environments produces unstable nuclei which again can be targets for subsequent reactions. In addition, it involves a large number of stable nuclides which are not fully explored by experiments, yet. Thus, it is necessary to be able to predict reaction cross sections and thermonuclear rates with the aid of theoretic

N. Masetti, E. Palazzi, E. Pian, A. Simoncelli

(Abridged) We report on observations of the optical and NIR afterglow of GRB020405. Ground-based optical observations started about 1 day after the GRB and spanned a period of ~10 days; archival HST data extended the coverage up to 70 days after the GRB. We report the first detection of the afterglow in NIR bands. The detection of emission lines in the optic

H. Kepa, G. Springholz, T. M. Giebultowicz, K. I. Goldman

The magnetic properties of antiferromagnetic (AFM) EuTe epitaxial layers and short period EuTe/PbTe superlattices (SLs), grown by molecular beam epitaxy on (111) BaF$_2$ substrates, were studied by magnetization and neutron diffraction measurements. Considerable changes of the Néel temperature as a function of the EuTe layer thickness as well as of the strai

Z. J. Ajaltouni, O. Leitner, P. Perret, C. Rimbault

We present a detailed study of direct CP violation and branching ratios in the channels $B^{0,\pm} \to π^{+}π^{-} V^{0,\pm}$, where $V$ is a vector meson ($K^{* 0,\pm}$ or $ρ^{\pm}$). Emphasis is placed upon the important role played by ${ρ^{0}}-ω$ mixing effects in the estimation of the CP-violating asymmetry parameter, $a_{cp}$, associated with the differe

Shinichi Deguchi, Yousuke Kokubo

We derive an effective Abelian gauge theory (EAGT) of a modified SU(2) Yang-Mills theory. The modification is made by explicitly introducing mass terms of the off-diagonal gluon fields into pure SU(2) Yang-Mills theory, in order that Abelian dominance at a long-distance scale is realized in the modified theory. In deriving the EAGT, the off-diagonal gluon fi

Zhi-Rong Liu, Jian Wu, Wenhui Duan

Based on the conventional energy band theory, an approach is presented to describe the electronic structure of crystalline insulators in the presence of a finite homogeneous electric field. The expression of polarization is derived which extends the ``Berry-phase&#39;&#39; theory of polarization to nonzero fields. The characteristics of the solutions are stu

P. Chung, N. N. Ajitanand, J. M. Alexander, M. Anderson

The yield for the multi-strange $Ξ^{-}$ hyperon has been measured in 6 AGeV Au+Au collisions via reconstruction of its decay products $π^{-}$ and $Λ$, the latter also being reconstructed from its daughter tracks of $π^{-}$ and p. The measurement is rather close to the threshold for $Ξ^{-}$ production and therefore provides an important test of model predicti

Y. X. Yao, X. N. Ying, Y. N. Huang, Y. N. Wang

The mechanical relaxation spectra of a superconducting and a non-superconducting MgCNi3 samples were measured from liquid nitrogen temperature to room temperature at frequency of kilohertz. There are two internal friction peaks (at 300 K labeled as P1 and 125 K as P2) for the superconducting sample. For the non-superconducting one, the position of P1 shifts

D. Auto, H. Baer, C. Balazs, A. Belyaev

We present an updated assessment of the viability of t-b-tau Yukawa coupling unification in supersymmetric models. For the superpotential Higgs mass parameter mu>0, we find unification to less than 1% is possible, but only for GUT scale scalar mass parameter m_{16}~8-20 TeV, and small values of gaugino mass m_{1/2}<400 GeV. Such models require that a GUT sca

A. K. Chaudhuri

We have analysed the latest NA50 data on $J/ψ$ production in pA and AA collisions. The $J/ψ$ production is assumed to be a two step process, (i) formation of $c\bar{c}$ pairs, perturbatively calculable, and (ii) formation of $J/ψ$ from the pair, a non-perturbative process, which is conviniently parametrized. In a nuclear medium, as the $c\bar{c}$ pair passes

S. Kasuya, M. Kawasaki, Fuminobu Takahashi

We investigate whether the Affleck-Dine (AD) mechanism works when the contribution of the two-loop thermal correction to the potential is negative in the gauge-mediated supersymmetry breaking models. The AD field is trapped far away from the origin by the negative thermal correction for a long time until the temperature of the universe becomes low enough. Th

T. R. Kendall, N. Mauron, M. Azzopardi, K. Gigoyan

We report the discovery of seven hitherto unknown L-dwarfs found as a result of a spectroscopic search for distant AGB stars. Their far-red and near-infrared colours are very similar to known dwarfs of the same spectral type. One new object is among the ~30 brightest L-dwarfs, with K_s=12.12, and is nearby, ~20pc. Using low resolution spectroscopy from the D

Richard Jozsa

Pell&#39;s equation is x^2-d*y^2=1 where d is a square-free integer and we seek positive integer solutions x,y>0. Let (x&#39;,y&#39;) be the smallest solution (i.e. having smallest A=x&#39;+y&#39;sqrt(d)). Lagrange showed that every solution can easily be constructed from A so given d it suffices to compute A. It is known that A can be exponentially large in

L. A. Caron, D. Huard, H. Kröger, G. Melkonyan

We investigate chaotic behavior in a 2-D Hamiltonian system - oscillators with anharmonic coupling. We compare the classical system with quantum system. Via the quantum action, we construct Poincaré sections and compute Lyapunov exponents for the quantum system. We find that the quantum system is globally less chaotic than the classical system. We also obser

Robert Alicki

The theory of controlled quantum open systems describes quantum systems interacting with quantum environments and influenced by external forces varying according to given algorithms. It is aimed, for instance, to model quantum devices which can find applications in the future technology based on quantum information processing. One of the main problems making

Th. Elsaesser, B. Nagorny, A. Hemmerich

We propose a cavity based laser cooling and trapping scheme, providing tight confinement and cooling to very low temperatures, without degradation at high particle densities. A bidirectionally pumped ring cavity builds up a resonantly enhanced optical standing wave which acts to confine polarizable particles in deep potential wells. The particle localization

L. Chetouani, L. Guechi, T. F. Hammann

The so$(2,1)$ Lie algebra is applied to three classes of two- and three-dimensional Smorodinsky-Winternitz super-integrable potentials for which the path integral discussion has been recently presented in the literature. We have constructed the Green&#39;s functions for two important super-integrable potentials in $R^{2}.$ Among the super-integrable potentia

Jian Qi Shen, San Shui Xiao, Qiang Wu

The present letter finds the complete set of exact solutions of the time-dependent generalized Cini model by making use of the Lewis-Riesenfeld invariant theory and the invariant-related unitary transformation formulation and, based on this, the general explicit expression for the decoherence factor is therefore obtained. This study provides us with a useful

Edward R. Floyd

The trajectory representation in the high energy limit (Bohr correspondence principle) manifests a residual indeterminacy. This indeterminacy is compared to the indeterminacy found in the classical limit (Planck&#39;s constant to 0) [Int. J. Mod. Phys. A 15, 1363 (2000)] for particles in the classically allowed region, the classically forbiden region, and ne

Mario Rabinowitz

The wave-particle duality is the main point of demarcation between quantum and classical physics, and is the quintessential mystery of quantum mechanics. Young&#39;s two-slit interference experiment is the arch prototype of actual and gedanken experiments used as a testing ground of this duality. Quantum mechanics predicts that any detector capable of determ

Claus O Wilke, Richard E Lenski, Christoph Adami

Background: The rate at which fitness declines as an organism&#39;s genome accumulates random mutations is an important variable in several evolutionary theories. At an intuitive level, it might seem natural that random mutations should tend to interact synergistically, such that the rate of mean fitness decline accelerates as the number of random mutations

Robin Santra, Chris H. Greene

Alkaline-earth atoms in their lowest triplet P_2 state are exceptionally long-lived and can be trapped magnetically. The nonspherical atomic structure leads to anisotropic long-range interactions between two metastable alkaline-earth atoms. The anisotropy affects the rotational motion of the diatomic system and couples states of different rotational quantum

A. P. Saiko

The Dicke superradiance on vibronic transitions of impurity crystals is considered. It is shown that parameters of the superradiance (duration and intensity of the superradiance pulse and delay times) on each vibronic transition depend on the strength of coupling of electronic states with the intramolecular impurity vibration (responsible for the vibronic st

Antonio Alfonso-Faus

When considering possible time variations of fundamental physical constants one has to keep firm well established principles. Following this approach we keep firm the Action Principle, General Relativity (the Equivalence Principle), and Mach&#39;s Principle. Also we introduce a new principle under the name of &#34;TOTAL INTERACTION&#34; and reconsider Weinbe

S. Janssen, D. G. Ireland, J. Ryckebusch

Nucleon resonance information is often obtained from fitting hadrodynamical model calculations to data, where model parameters such as resonance coupling constants are the free parameters in the fitting procedure. For reactions with a limited data set, such as p(gamma, K+)Lambda, complications in the extraction of reliable N* information occur not only throu

D. Mocelj, T. Rauscher, G. Martinez-Pinedo, Y. Alhassid

A simple description for obtaining the parity distribution of nuclear levels in the pf + g9/2 shell as a function of excitation energy was recently derived. We implement this in a global nuclear level density model. In the framework of the statistical model, cross sections and astrophysical reaction rates are calculated in the Fe region and compared to rates

Ricardo Lopez-Ruiz, Stefano Boccaletti

The conditions for the existence of heteroclinic connections between the transverse modes of a CO2 laser whose setup has a perfect cylindrical symmetry are discussed by symmetry arguments for the cases of three, four and five interacting modes. Explicit conditions for the parameters are derived, which can guide observation of such phenomena.

M. A. Fuentes, M. N. Kuperman, V. M. Kenkre

We consider a model for population dynamics such as for the evolution of bacterial colonies which is of the Fisher type but where the competitive interaction among individuals is non-local, and show that spatial structures with interesting features emerge. These features depend on the nature of the competitive interaction as well as on its range, specificall

Victor S. L&#39;vov, Ruben Pasmanter, Anna Pomyalov, Itamar Procaccia

The weak version of universality in turbulence refers to the independence of the scaling exponents of the $n$th order strcuture functions from the statistics of the forcing. The strong version includes universality of the coefficients of the structure functions in the isotropic sector, once normalized by the mean energy flux. We demonstrate that shell models

E. I. Semenov

The invariance for the equation of fast diffusion in the 2D coordinate space has been proved, and its reduction to the 1D (with respect to the spatial variable) analog is demonstrated. On the basis of these results, new exact multi-dimensional solutions, which are dependent on arbitrary harmonic functions, are constructed. As a result, new exact solutions of

Dimitri Shlyakhtenko

We show that Ozawa&#39;s recent results on solid von Neumann algebras imply that there are free Araki-Woods factors, which fail to have free absorption. We also show that a free Araki-Woods factors $Γ(μ, n)$ associated to a measure and a multiplicity function $n$ may non-trivially depend on the multiplicity function.

Randall D. Peters

For a sample set of 1024 values, the FFT is 102.4 times faster than the discrete Fourier transform (DFT). The basis for this remarkable speed advantage is the `bit-reversal&#39; scheme of the Cooley-Tukey algorithm. Eliminating the burden of `degeneracy&#39; by this means is readily understood using vector graphics.

Wei-Ping Li, Zhenbo Qin, Weiqiang Wang

Various equivariant intersection numbers on Hilbert schemes of points on the affine plane are computed, some of which are organized into tau-functions of 2-Toda hierarchies. A correspondence between the equivariant intersection on Hilbert schemes and stationary Gromov-Witten theory is established.

Jochen Heinloth

The aim of these notes is to generalize Laumon&#39;s construction [18] of automorphic sheaves corresponding to local systems on a smooth, projective curve $C$ to the case of local systems with indecomposable unipotent ramification at a finite set of points. To this end we need an extension of the notion of parabolic structure on vector bundles to coherent sh

Francesca Gavioli

Let X be a smooth projective connected curve of genus $g \ge 2$ and let I be a finite set of points of X. Fix a parabolic structure on I for rank r vector bundles on X. Let $M^{par}$ denote the moduli space of parabolic semistable bundles and let $L^{par}$ denote the parabolic determinant bundle. In this paper we show that the n-th tensor power line bundle $

Indranil Biswas, Avijit Mukherjee

Parabolic triples of the form $(E_*,θ,σ)$ are considered, where $(E_*,θ)$ is a parabolic Higgs bundle on a given compact Riemann surface $X$ with parabolic structure on a fixed divisor $S$, and $σ$ is a nonzero section of the underlying vector bundle. Sending such a triple to the Higgs bundle $(E_*,θ)$ a map from the moduli space of stable parabolic triples

Bertrand Morel

We show that it is natural to consider the energy-momentum tensor associated with a spinor field as the second fundamental form of an isommetric immersion. In particular we give a generalization of the warped product construction over a Riemannian manifold leading to this interpretation. Special sections of the spinor bundle, generalizing the notion of Killi

Alexander Premet

We prove that the nilpotent commuting variety of a reductive Lie algebra over an algebraically closed field of good characteristic is equidimensional. In characteristic zero, this confirms a conjecture of Vladimir Baranovsky. As a by-product, we obtain tat the punctual (local) Hilbert scheme parametrising the ideals of colength $n$ in $k[[X,Y]]$ is irreducib

Vladimir Ivanov, Sergei Kerov

We prove a convolution formula for the conjugacy classes in symmetric groups conjectured by the second author. A combinatorial interpretation of coefficients is provided. As a main tool we introduce new semigroup of partial permutations. We describe its structure, representations, and characters. We also discuss filtrations on the subalgebra of invariants in

B. Shapiro, M. Shapiro, A. Vainshtein

We study the distribution of the number of permutations with a given periodic up-down sequence w.r.t. the last entry, find exponential generating functions and prove asymptotic formulas for this distribution.

George A. Willis

Let αbe an automorphism of the totally disconnected group G. The compact open subgroup, V, if G is tidy for αif [α(V&#39;) : α(V&#39;)\cap V&#39;] is minimised at V, where V&#39; ranges over all compact open subgroups of G. Identifying a subgroup tidy for αis analogous to identifying a basis which puts a linear transformation into Jordan canonical form. This

Ronaldo Garcia, Jorge Sotomayor

Consider oriented surfaces immersed in $\mathbb R^3.$ Associated to them, here are studied pairs of transversal foliations with singularities, defined on the Elliptic region, where the Gaussian curvature $\mathcal K$, given by the product of the principal curvatures $k_1, k_2$ is positive. The leaves of the foliations are the lines of harmonic mean curvature

Bertrand Morel

We generalize the spinorial characterization of isometric immersions of surfaces in R^3 given by T. Friedrich (On the spinor representation of surfaces in Euclidean 3-space, J. Geom. Phys. 28 (1998)) to surfaces in S^3 and H^3. The main argument is the interpretation of the energy-momentum tensor associated with a special spinor field as a second fundamental

Weiqiang Wang

The Jucys-Murphy elements for wreath products G_n associated to any finite group G are introduced and they play an important role in our study on the connections between class algebras of G_n for all n and vertex algebras. We construct an action of (a variant of) the W_{1+\infty} algebra acting irreducibly on the direct sum R_G of the class algebras of G_n f

D. K. Park, S. Tamaryan, H. J. W. Müller-Kirsten

The supertube and BIon spike solutions are examined in a general curved target space. The criteria for the existence of these solutions are explicitly derived. Also the equation which the general BIon solution should satisfy is derived.

Hubert Saleur, Birgit Wehefritz-Kaufmann

As a step to understand general patterns of integrability in 1+1 quantum field theories with supergroup symmetry, we study in details the case of $OSP(1/2)$. Our results include the solutions of natural generalizations of models with ordinary group symmetry: the $UOSP(1/2)_{k}$ WZW model with a current current perturbation, the $UOSP(1/2)$ principal chiral m

Stefan Leupold

The heat kernel method is extended to the case of finite temperature. Special emphasis is given to the study of gauge theories. Due to the compactness of space in the Euclidean time direction (inverse temperature) the field strength cannot completely characterize the gauge fields. This is just a manifestation of the Aharonov-Bohm effect. The field strength h

D. V. Shirkov

Integral transformations of the QCD invariant (running) coupling and of some related objects are discussed. Special attention is paid to the Fourier transformation, that is to transition from the space-time to the energy--momentum representation. The conclusion is that the condition of possibility of such a transition provides us with one more argument again

P. Mastrolia, E. Remiddi

We evaluate the on shell form factors of the electron for arbitrary momentum transfer and finite electron mass, at two loops in QED, by integrating the corresponding dispersion relations, which involve the imaginary parts known since a long time. The infrared divergences are parameterized in terms of a fictitious small photon mass. The result is expressed in

M. Fairbairn, L. Lopez-Honorez, M. H. G. Tytgat

We propose an extension to the recently proposed extranatural or gauge inflation scenario in which the radius modulus field around which the Wilson loop is wrapped assists inflation as it shrinks. We discuss how this might lead to more generic initial conditions for inflation.

John D. Barrow, Sigbjorn Hervik

We show that generic anisotropic universes arbitrarily close to the open Friedmann universe allow information processing to continue into the infinite future if there is no cosmological constant or stable gravitationally repulsive stress, and the spatial topology is non-compact. An infinite amount of information can be processed by ``civilisations&#39;&#39;

Yasushi Mino

A charge-free, point particle of infinitesimal mass orbiting a Kerr black hole is known to move along a geodesic. When the particle has a finite mass or charge, it emits radiation which carries away orbital energy and angular momentum, and the orbit deviates from a geodesic. In this paper we assume that the deviation is small and show that the half-advanced

Paulo M. Sá

We investigate three-dimensional perfect fluid stars with polytropic equation of state, matched to the exterior three-dimensional black hole geometry of Banados, Teitelboim and Zanelli. A new class of exact solutions for a generic polytropic index is found and analysed.

Kirill Krasnov

We use the analytic continuation procedure proposed in our earlier works to study the thermodynamics of black holes in 2+1 dimensions. A general black hole in 2+1 dimensions has g handles hidden behind h horizons. The result of the analytic continuation is a hyperbolic 3-manifold having the topology of a handlebody. The boundary of this handlebody is a compa

Gioel Calabrese, Luis Lehner, David Neilsen, Jorge Pullin

We use rigorous techniques from numerical analysis of hyperbolic equations in bounded domains to construct stable finite-difference schemes for Numerical Relativity, in particular for their use in black hole excision. As an application, we present 3D simulations of a scalar field propagating in a Schwarzschild black hole background.

Marek Biskup, Lincoln Chayes, Roman Kotecky

We examine some aspects of the recent results by K. Binder. The equilibrium formation/dissolution of droplets in finite systems is discussed in the context of the canonical and the grand canonical distributions.

D. R. Strachan, C. J. Lobb, R. S. Newrock

There has been ongoing debate over the critical behavior of two-dimensional superconductors; in particular for high Tc superconductors. The conventional view is that a Kosterlitz-Thouless-Berezinskii transition occurs as long as finite size effects do not obscure the transition. However, there have been recent suggestions that a different transition actually

Per Arne Rikvold, M. Kolesik

We present theoretical and dynamic Monte Carlo simulation results for the mobility and microscopic structure of 1+1-dimensional Ising interfaces moving far from equilibrium in an applied field under a single-spin-flip ``soft&#39;&#39; stochastic dynamic. The soft dynamic is characterized by the property that the effects of changes in field energy and interac

Jean-Marc Debierre, Alain Karma, Franck Celestini, Rahma Guerin

We extend the phase-field approach to model the solidification of faceted materials. Our approach consists of using an approximate gamma-plot with rounded cusps that can approach arbitrarily closely the true gamma-plot with sharp cusps that correspond to faceted orientations. The phase-field equations are solved in the thin-interface limit with local equilib