April 2004 arXiv papers — page 6

Takeshi Katsura

We investigate C^*-algebras generated by scaling elements. We generalize the Wold decomposition and Coburn's theorem on isometries to scaling elements. We also completely determine when the C^*-algebra generated by a scaling element contains an infinite projection.

Hiroshi Sato

In this paper, we give explicit combinatorial descriptions for toric extremal contractions under the relative setting, where varieties do not need to be complete. Fujino's completion theorem is the key to the main result. As applications, we can generalize some of Mustata's results related to Fujita's conjecture on toric varieties for the relativ

Quan Zheng, Xiaohua Yao, Da Fan

This paper is concerned with Schrödinger equations whose principal operators are homogeneous elliptic. When the corresponding level hypersurface is convex, we show the $L^p$-$L^q$ estimate of solution operator in free case. This estimate, combining with the results of fractionally integrated groups, allows us to further obtain the $L^p$ estimate of solutions

Wim Couwenberg, Gert Heckman, Eduard Looijenga

Consider a complex projective space with its Fubini-Study metric. We study certain one parameter deformations of this metric on the complement of an arrangement (=a finite union of hyperplanes) whose Levi-Civita connection is of Dunkl type--interesting examples are obtained from the arrangements defined by finite complex reflection groups. We determine a par

Timothy Prescott, Francis Edward Su

Our paper gives bounds for the rate of convergence for a class of random walks on the d-dimensional torus generated by a set of n vectors in R^d/Z^d. We give bounds on the discrepancy distance from Haar measure; our lower bound holds for all such walks, and if the generators arise from the rows of a "badly approximable" matrix, then there is a corres

Norman Cruz, Samuel Lepe

We investigate the limitations on the thermal description of three dimensional BTZ black holes. We derive on physical grounds three basic mass scales that are relevant to characterize these limitations. The Planck mass in 2+1 dimensions indicate the limits where the black hole can emit Hawking's radiation. We show that the back reaction is meaningless fo

Metin Aktas, Ramazan Sever

Supersymmetric solution of PT-/non-PT-symmetric and non-Hermitian Morse potential is studied to get real and complex-valued energy eigenvalues and corresponding wave functions. Hamiltonian Hierarchy method is used in the calculations

Jose Gaite

The exact or Wilson renormalization group equations can be formulated as a functional Fokker-Planck equation in the infinite-dimensional configuration space of a field theory, suggesting a stochastic process in the space of couplings. Indeed, the ordinary renormalization group differential equations can be supplemented with noise, making them into stochastic

Amir H. Fatollahi, Hossein Mohammadzadeh

One approach for formulating the classical dynamics of charged particles in non-Abelian gauge theories is due to Wong. Following Wong's approach, we derive the classical equations of motion of a charged particle in U(1) gauge theory on noncommutative space, the so-called noncommutative QED. In the present use of the procedure, it is observed that the def

J. Kluson

In this paper we propose the toy model of the closed string tachyon effective action that has marginal tachyon profile as its exact solution in case of constant or linear dilaton background. Then we will apply this model for description of two dimensional bosonic string theory. We will find that the background configuration with the spatial dependent linear

Yuuichirou Shibusa

We propose a physical interpretation of our novel fermionic solution for the IKKT matrix model which obtained in our previous paper hep-th/0307236. We extend the configuration space of bosonic field to supernumbers space and obtain the noncommutative parameter which is not bi-grassmann but an ordinary number. This establishes the connection between Seiberg&#

B. Sathiapalan

The prescription of Kawai, Lewellen and Tye for writing the closed string tree amplitudes as sums of products of open string tree amplitudes, is applied to the world sheet renormalization group equation. The main point is that regularization of the Minkowski (rather than Euclidean) world sheet theory allows factorization into left-moving and right-moving sec

Takao Koikawa

We study the quantization of compact space on the basis of the Moyal quantization. We first construct the $su(2)$ algebra that are the functions of canonical coordinates $a$ and $a^*$. We make use of them to define the adjoint operators, which is used to define the fuzzy sphere and constitute the algebra. We show that the vacuum is constructed as the powers

Maciej Slusarczyk

We present a determination of a new class of Feynman diagrams relevant for second-order QCD corrections to the top quark decay t -> b W. Modern computing techniques allow us to perform a reduction of the original loop integrals to master integrals. We obtain the analytical value of the top decay rate as an expansion around the limit of massless b and W.

Bing An Li

The form factor π^0γ^*γ^* is obtained to the next leading order of derivative expansion of the chiral anomaly and the VMD. As a test the form factor has been used to calculate the cross section of ee^+-->π^0γ. Theory agrees with data.

S. Hamieh, A. Tawfik

The entanglement at finite temperatures are analyzed by using thermal models for colored quarks making up the hadron physical states. We have found that these quantum correlations entirely vanish at $T_c\geq m_q/\ln(1.5)$. For temperatures larger than $T_c$ the correlations are classical. Also we worked out the entanglement for the transverse Ising spin chai

F. Cornet, P. Jankowski, M. Krawczyk

Radiatively generated, LO quark (u,d,s,c,b) and gluon densities in the real, unpolarized photon, improved in respect to our previous paper, are presented. We perform three global fits to the F_2^gamma data, using the LO DGLAP evolution equation. We improve the treatment of the strong coupling running and used lower values of Lambda_QCD, as we have found that

P. Bartalini, L. Dudko, A. Kryukov, I. Seluzhenkov

We present the Monte-Carlo events Data Base (MCDB) project and its development plans. MCDB facilitates communication between authors of Monte-Carlo generators and experimental users. It also provides a convenient book-keeping and an easy access to generator level samples. The first release of MCDB is now operational for the CMS collaboration. In this paper w

Stefano Catani, Daniel de Florian, German Rodrigo, Werner Vogelsang

We point out that perturbative evolution in QCD at three loops generates a strange-antistrange asymmetry s(x)-sbar(x) in the nucleon's sea just from the fact that the nucleon has non-vanishing up and down quark valence densities. The recently computed three-loop splitting functions allow for an estimate of this effect. We find that a fairly sizable asymm

Steen Hannestad

The current status of neutrino cosmology is reviewed, from the question of neutrino decoupling and the presence of sterile neutrinos to the effects of neutrinos on the cosmic microwave background and large scale structure. Particular emphasis is put on cosmological neutrino mass measurements.

Otto C. W. Kong

We discuss extensions of the Standard Model through extending the electroweak gauge symmetry. An extended electroweak symmetry requires a list of extra fermionic and scalar states. The former is necessary to maintain cancellation of gauge anomalies, and largely fixed by the symmetry embedding itself. The latter is usually considered quite arbitrary, so long

S. A. Abel, J. Santiago

String and field theory ideas have greatly influenced each other since the so called second string revolution. We review this interrelation paying particular attention to its phenomenological implications. Our guiding principle is the radical shift in the way that we think about the fundamental scale, in particular the way in which string models have been ab

E. Accomando, A. Ballestrero, E. Maina

PHASE is a Monte Carlo event generator, under construction, for all Standard Model processes with six fermions in the final state at the LHC. It employs the full set of tree level Feynman diagrams, taking into account fermion masses for b quarks. The program can generate unweighted events for any subset of all six fermion final states in a single run, by mak

V. Cirigliano, A. Kurylov, M. J. Ramsey-Musolf, P. Vogel

We study the lepton flavor violating (LFV) processes mu -> e gamma, mu -> 3e, and mu -> e conversion in nuclei in the left-right symmetric model without supersymmetry and perform the first complete computation of the LFV branching ratios B(mu -> f) to leading non-trivial order in the ratio of left- and right-handed symmetry breaking scales. To this order, B(

Adam Bzdak

Using the Landshoff-Nachtmann two-gluon exchange model of the pomeron, the double pomeron exchange contribution to production of gluon pairs in the central region of rapidity is calculated. The results are compared with those for production of quark-antiquark pairs.

Jorge Paramos

In this work we address the impact of a cubic term addition to the Ginzburg-Landau mean-field potential, and study the consequences on the description of first order phase transitions in superconductors. Constraints are obtained from experiment and used to assess consequences on topological defect creation. No fundamental changes in either the Kibble-Zurek o

Ulrich D. Jentschura

The subjects which are discussed in this Thesis include: the self energy of a bound electron and the spin-dependence of QED corrections in bound systems, convergence acceleration techniques, and resummation methods for divergent series with an emphasis on physical applications.

Romulus Godang, Donald Summers

Based on a data sample of 81.7 fb^-1 collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC, we present the current status of the measurement of the branching fraction of Upsilon(4S) to B0bar B^0. Our study of the decay was performed through the exclusive decays B0bar to D^{*+} \ell^{-} barν_{\ell} us

Kamiokande Collaboration, Y. Ashie

Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu_mu <-> nu_tau neutrino oscillation parameters; 1.9x10

Mariam Bouhmadi-Lopez, Paulo Vargas Moniz

Cosmologies with a Chaplygin gas have recently been explored with the objective of explaining the transition from a dust dominated epoch towards an accelerating expansion stage. We consider the hypothesis that the transition to the accelerated period involves a quantum mechanical process. Three physically admissible cases are possible. In particular, we iden

Hirotaka Yoshino, Yasusada Nambu

It is known that the formation of apparent horizons with non-spherical topology is possible in higher-dimensional spacetimes. One of these is the black ring horizon with $S^1\times S^{D-3}$ topology where $D$ is the spacetime dimension number. In this paper, we investigate the black ring horizon formation in systems with $n$-particles. We analyze two kinds o

Iver Brevik

The holographic principle in a radiation dominated universe, as discussed first by Verlinde (2000), is extended so as to incorporate the case of a bulk-viscous cosmic fluid. This corresponds to a non-conformally invariant theory. Generalization of the Cardy-Verlinde entropy formula to the viscous case appears to be formally possible, although on physical gro

James M. Nester, Feng-Feng Meng, Chiang-Mei Chen

Gravitating systems have no well-defined local energy-momentum density. Various quasilocal proposals have been made, however the center-of-mass moment (COM) has generally been overlooked. Asymptotically flat graviating systems have 10 total conserved quantities associated with the Poincar{é} symmetry at infinity. In addition to energy-momentum and angular mo

Roberto Bagnara, Roberta Gori, Patricia M. Hill, Enea Zaffanella

Logic languages based on the theory of rational, possibly infinite, trees have much appeal in that rational trees allow for faster unification (due to the safe omission of the occurs-check) and increased expressivity (cyclic terms can provide very efficient representations of grammars and other useful objects). Unfortunately, the use of infinite rational tre

Manfred Sigrist, Matthias Troyer

The alloy Ca$_{2-x}$Sr$_x$RuO$_4$ exhibits a complex phase diagram with peculiar magnetic metallic phases. In this paper some aspects of this alloy are discussed based on a mean field theory for an effective Kugel-Khomskii model of localized orbital and spin degrees of freedom. This model results from an orbital selective Mott transition which in the three-b

K. Ramesha, Ram Seshadri, Claude Ederer, Tao He

Bulk samples of the pyrite chalcogenide solid solutions Co$_{1-x}$Fe$_x$S$_2$ 0 <= x <= 0.5, have been prepared and their crystal structures and magnetic properties studied by X-ray diffraction and SQUID magnetization measurements. Across the solution series, the distance between sulfur atoms in the persulfide (S$_2^{2-}$) unit remains nearly constant. First

B. Wemmenhove, N. S. Skantzos

We present an analytically solvable random graph model in which the connections between the nodes can evolve in time, adiabatically slowly compared to the dynamics of the nodes. We apply the formalism to finite connectivity attractor neural network (Hopfield) models and we show that due to the minimisation of the frustration effects the retrieval region of t

Hai Qian, Gene F. Mazenko

We study the motion of vortices in the conserved and non-conserved phase-ordering models. We give an analytical method for computing the speed and position distribution functions for pairs of annihilating point vortices based on heuristic scaling arguments. In the non-conserved case this method produces a speed distribution function consistent with previous

H. Touchette, R. S. Ellis, B. Turkington

This short paper presents a nontechnical introduction to the problem of nonequivalent microcanonical and canonical ensembles. Both the thermodynamic and the macrostate levels of definition of nonequivalent ensembles are introduced. The many relationships that exist between these two levels are also explained in simple physical terms.

Marco Pretti

In this article we investigate on the convergence of the natural iteration method, a numerical procedure widely employed in the statistical mechanics of lattice systems to minimize Kikuchi&#39;s cluster variational free energies. We discuss a sufficient condition for the convergence, based on the coefficients of the cluster entropy expansion, depending on th

A. V. Avdeenkov, J. L. Bohn

Recent experiments have observed condensation behavior in a strongly interacting system of fermionic atoms. We interpret these observations in terms of a mean-field version of resonance superfluidity theory. We find that the objects condensed are not bosonic molecules composed of bound fermion pairs, but are rather spatially correlated Cooper pairs whose coh

Girish Nathan, Gemunu Gunaratne

We introduce a set of statistical measures that can be used to quantify non-equilibrium surface growth. They are used to deduce new information about spatiotemporal dynamics of model systems for spinodal decomposition and surface deposition. Patterns growth in the Cahn-Hilliard Equation (used to model spinodal decomposition) are shown to exhibit three distin

Neill E. Bowler, Robin C. Ball

Using off-lattice noise reduction it is possible to estimate the asymptotic properties of diffusion-limited aggregation clusters grown in three dimensions with greater accuracy than would otherwise be possible. The fractal dimension of these aggregates is found to be 2.50 +/- 0.01, in agreement with earlier studies, and the asymptotic value of the relative p

Napoleon Anento, Luis E. Gonzalez, David J. Gonzalez, Yaroslav Chushak

This paper presents the viscoelastic model for the Ashcroft-Langreth dynamic structure factors of liquid binary mixtures. We also provide expressions for the Bhatia-Thornton dynamic structure factors and, within these expressions, show how the model reproduces both the dynamic and the self-dynamic structure factors corresponding to a one-component system in

P. Caputo, J. Oppenlaender, Ch. Haeussler, J. Tomes

We have developed an absolute magnetic field sensor using Superconducting Quantum Interference Filter (SQIF) made of high-T_c grain boundary Josephson junctions. The device shows the typical magnetic field dependent voltage response V(B), which is sharp delta-like dip in the vicinity of zero magnetic field. When the SQIF is cooled with magnetic shield, and t

Y. Oshima, E. Jobiliong, T. Tokumoto, J. S. Brooks

Submillimeter and millimeter wave electron spin resonance (ESR) measurements of the pi-d correlated organic conductor lambda-(BETS)2Fe0.6Ga0.4Cl4 have been performed. Antiferromagnetic resonance (AFMR) has been observed in the insulating antiferromagnetic phase, and its frequency-field dependence can be reproduced by the biaxial anisotropic AFMR theory. We f

G. Gomez-Santos, S. Fratini, F. Guinea

Transport properties of itinerant electrons interacting with local spins are analyzed as function of the bandwidth, $W$, the exchange interaction, $J$, and the band filling, $n$, near the band edge. Numerical results have been obtained within the dynamical mean-field approximation and interpreted with the help of analytical treatments. If spatial correlation

M. E. Cates, K. Stratford, R. Adhikari, P. Stansell

We present a progress report on our work on lattice Boltzmann methods for colloidal suspensions. We focus on the treatment of colloidal particles in binary solvents and on the inclusion of thermal noise. For a benchmark problem of colloids sedimenting and becoming trapped by capillary forces at a horizontal interface between two fluids, we discuss the criter

P. Jain, C. W. Gardiner

We present a phase-space method for the Bose-Hubbard model based on the Q-function representation. In particular, we consider two model Hamiltonians in the mean-field approximation; the first is the standard &#34;one site&#34; model where quantum tunneling is approximated entirely using mean-field terms; the second &#34;two site&#34; model explicitly include

J. Schriefl, M. Clusel, D. Carpentier, P. Degiovanni

Motivated by recent experiments with Josephson qubits we propose a new phenomenological model for 1/f noise due to collective excitations of interacting defects in the qubit&#39;s environment. At very low temperatures the effective dynamics of these collective modes are very slow leading to pronounced non-Gaussian features and nonstationarity of the noise. W

Subhasis Banerjee, Shrestha Basu Mallik, Indrani Bose

We study the discrete Gierer-Meinhardt model of reaction-diffusion on three different types of networks: regular, random and scale-free. The model dynamics lead to the formation of stationary Turing patterns in the steady state in certain parameter regions. Some general features of the patterns are studied through numerical simulation. The results for the ra

S. V. Demishev, A. V. Semeno, N. E. Sluchanko, N. A. Samarin

Resonant magnetoabsorption spectra for CuGeO3 single crystals containing 2% of Co impurity are studied in the frequency range 60-360 GHz in magnetic field up to 16 T at temperatures 2-60 K. It is found that together with the resonance on Cu2+ chains a new absorption line related with Co2+ ions appears in EPR spectrum. The full set of spectroscopic data (g-fa

J. G. Rodrigo, S. Vieira

We present a method to produce superconducting tips to be used in Scanning Tunneling Microscopy/Spectroscopy experiments. We use these tips to investigate the evolution of the electronic density of states of NbSe2 from 0.3K up to its critical temperature (7.2K). The use of a superconducting tip (Pb) as ounterelectrode provides an enhancement of the different

Ludger Wirtz, Angel Rubio

We review calculations and measurements of the phonon-dispersion relation of graphite. First-principles calculations using density-functional theory are generally in good agreement with the experimental data since the long-range character of the dynamical matrix is properly taken into account. Calculations with a plane-wave basis demonstrate that for the in-

Y. H. Matsuda, G. A. Khodaparas, M. A. Zudov, J. Kono

We have carried out an ultrahigh-field cyclotron resonance study of p-type In1-xMnxAs films, with Mn composition x ranging from 0% to 2.5%, grown on GaAs by low-temperature molecular-beam epitaxy. Pulsed magnetic fields up to 500 T were used to make cyclotron resonance observable in these low-mobility samples. The clear observation of hole cyclotron resonanc

Y. Jiang, S. Abe, T. Ochiai, T. Nozaki

Recently it has been predicted that a spin-polarized electrical current perpendicular-to-plane (CPP) directly flowing through a magnetic element can induce magnetization switching through spin-momentum transfer. In this letter, the first observation of current-induced magnetization switching (CIMS) in exchange-biased spin-valves (ESPVs) at room temperature i

M. A. Skvortsov, D. M. Basko, V. E. Kravtsov

We consider energy absorption in an externally driven complex system of noninteracting fermions with the chaotic underlying dynamics described by the unitary random matrices. In the absence of quantum interference the energy absorption rate W(t) can be calculated with the help of the linear-response Kubo formula. We calculate the leading two-loop interferenc

G. Li, P. Zheng, N. L. Wang, Y. Z. Long

Localization driven by disorder has a strong influence on the conducting property of conducting polymer. A class of authors hold the opinion that disorder in the material is homogeneous and conducting polymer is disordered metal close to Anderson-Mott Metal-Insulator transition, while others treat the disorder as inhomogeneous and have the conclusion that co

Masao Arai, Takafumi Kita

We report on quantitative calculations of the upper critical field $H_{c2}$ for clean type-II superconductors Nb, NbSe$_{2}$, and MgB$_{2}$ using Fermi surfaces from {\em ab initio} electronic structure calculations. The results for Nb and NbSe$_2$ excellently reproduce both temperature and directional dependences of measured $H_{c2}$ curves without any adju

Károly Németh, Matt Challacombe

This article presents a new and efficient alternative to well established algorithms for molecular geometry optimization. The new approach exploits the approximate decoupling of molecular energetics in a curvilinear internal coordinate system, allowing separation of the 3N-dimensional optimization problem into an O(N) set of quasi-independent one-dimensional

Daniel Huertas-Hernando, Y. Alhassid

We derive a closed expression for the finite-temperature conductance of a Coulomb-blockade quantum dot in the presence of an exchange interaction and a parallel magnetic field. Parallel-field dependence of Coulomb-blockade peak position has been used to determine experimentally the ground-state spin of quantum dots. We find that for a realistic value of the

R. Vilela Mendes

Networks have been studied mainly using statistical methods. Here I collect some dynamical systems tools which are useful to study both the dynamics on networks and their evolution. They include decomposition of differential dynamics, ergodic invariants and estimates of invariant measures by small random perturbations. A few network examples are discussed as

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

A strong effect of sample size on magnetic Jc(H) was observed for bulk MgB2 when Jc is obtained directly from the critical state model. Thus obtained zero-field Jc (Jc0) decreases strongly with the sample size, attaining a constant value for the samples larger than a few millimetres. On the other hand, the irreversibility field (Hirr) defined at Jc = 100 A/c

Alan H. Guth

The basic workings of inflationary models are summarized, along with the arguments that strongly suggest that our universe is the product of inflation. I describe the quantum origin of density perturbations, giving a heuristic derivation of the scale invariance of the spectrum and the leading corrections to scale invariance. The mechanisms that lead to etern

C. Law, F. Yusef-Zadeh

We report the first detection of X-ray emission from the Quintuplet star cluster and compare its X-ray emission to that of the Arches star cluster. Four point sources are significantly detected near the core of the Quintuplet cluster with a total, absorption-corrected luminosity of ~1\times10^{33} ergs s^{-1}. Diffuse, thermal emission is also detected near

L. C. Bassett, W. N. Brandt, D. P. Schneider, C. Vignali

We present the results of Chandra observations of six radio-loud quasars (RLQs) and one optically bright radio-quiet quasar (RQQ) at z = 4.1-4.4. These observations cover a representative sample of RLQs with moderate radio-loudness (R ~ 40-400), filling the X-ray observational gap between optically selected RQQs and the five known blazars at z > 4 (R ~ 800-2

Tod E. Strohmayer

We report on X-ray spectroscopic observations with XMM/Newton of the ultracompact, double white dwarf binary, GP Com. With the Reflection Grating Spectrometers (RGS) we detect the Lyman alpha and beta lines of hydrogen-like nitrogen (N VII) and neon (Ne X), as well as the helium-like triplets (N VI and Ne IX) of these same elements. All the emission lines ar

Maciej Konacki, Guillermo Torres, Dimitar D. Sasselov, Grzegorz Pietrzynski

We report the independent discovery of a new extrasolar transiting planet around OGLE-TR-113, a candidate star from the Optical Gravitational Lensing Experiment. Small radial-velocity variations have been detected based on observations conducted with the MIKE spectrograph on the Magellan I (Baade) telescope at the Las Campanas Observatory (Chile) during 2003

Mariam Bouhmadi-Lopez, Jose A. Jimenez Madrid

We discuss dark energy models which might describe effectively the actual acceleration of the universe. More precisely, for a 4-dimensional Friedmann-Lema\^ıtre-Robertson-Walker (FLRW) universe we consider two situations: First of them, we model dark energy by phantom energy described by a perfect fluid satisfying the equation of state $P=(β-1)ρ$ (with $β<0$

Bradley M. Peterson

We have reanalyzed in a consistent way existing reverberation data for 35 AGNs for the purpose of refining the black hole masses derived from these data. We find that the precision (or random component of the error) of reverberation-based black hole mass measurements is typically around 30%, comparable to the precision attained in measurement of black hole m

Steinn Sigurdsson, Stephen E. Thorsett

The combination of ever more precise radio timing data and serendipitous {\it HST} data has confirmed that the outer companion to PSR B1620$-$26 is a planet. Here we summarize the observational situation, including preliminary new timing solutions and the implications of the measured system parameters. We detail the proposed formation scenarios, discussing t

Ofer Lahav

The 2dF Galaxy Redshift Survey (2dFGRS) of 230,000 redshifts of nearby (z~0.1) galaxies is now complete. It has allowed the 2dFGRS team and others to estimate fundamental cosmological parameters and to study galaxy intrinsic properties. Here we highlight three recent key results from the survey: (i) an upper limit of about 2eV on the total mass of the three

Todor Stanev

We discuss the contribution of proton photoproduction interactions on the isotropic infrared/optical background to the cosmic neutrino fluxes. This contribution has a strong dependence on the proton injection energy spectrum, and is essential at high redshifts. It is thus closely correlated with the cosmological evolution of the ultra high energy proton sour

W. Bednarek, G. F. Burgio, T. Montaruli

We review recently developed models of galactic discrete sources of high energy neutrinos. Some of them are based on a simple rescaling of the TeV $γ$-ray fluxes from recently detected galactic sources, such as, shell-type supernova remnants or pulsar wind nebulae. Others present detailed and originally performed modeling of processes occurring close to comp

M. Pozzo, W. P. S. Meikle, A. Fassia, T. Geballe

We present late-time near-infrared (NIR) and optical observations of the type IIn SN 1998S. The NIR photometry spans 333-1242 days after explosion, while the NIR and optical spectra cover 333-1191 days and 305-1093 days respectively. The NIR photometry extends to the M&#39;-band (4.7 mu), making SN 1998S only the second ever supernova for which such a long I

Gilles Chabrier

We determine the expected surface brightness and photometric signature of a white dwarf remnant population, issued from primordial low-mass stars formed at high redshifts, in today galactic halos. We examine the radial dependence of such a contribution as well as its redshift dependence. Such a halo diffuse radiation is below the detection limit of present l

E. Verner, B. A. Peterson

Interpretation of the \ion{Fe}{2}(UV)/\ion{Mg}{2} emission ratios from quasars has a major cosmological motivation. Both Fe and Mg are produced by short-lived massive stars. In addition, Fe is produced by accreting white dwarf supernovae somewhat after star formation begins. Therefore, we expect that the Fe/Mg ratio will gradually decrease with redshift. We

A. D. Erlykin, A. W. Wolfendale

Recent findings indicate that the Monogem Ring supernova remnant (SNR) and the associated pulsar B0656+14 may be the &#39;Single Source&#39; responsible for the knee in the cosmic ray (CR) energy spectrum at ~3 PeV. We estimate the contribution of this pulsar to CR in the PeV region. We conclude that although the pulsar can contribute to the formation of the

Diego Casadei

The Alpha Magnetic Spectrometer (AMS) is a cosmic ray (CR) experiment that will operate on the International Space Station for three years, measuring the particle spectra in the rigidity range from 0.2 GV to 2 TV. The AMS-02 detector will provide measurements with unprecedented statistics of the hadronic and leptonic cosmic rays, allowing for a better study

O. Kochukhov, T. Ryabchikova, J. D. Landstreet, W. W. Weiss

We describe an analysis of the time-resolved measurements of the surface magnetic field in the roAp star gamma Equ. We have obtained a high-resolution and high S/N spectroscopic time-series, and the magnetic field was determined using Zeeman resolved profiles of the Fe II 6149.25 A and Fe I 6173.34 A lines. Contrary to recent reports we do not find any evide

V. Bozza, L. Mancini

Light rays passing very close to a black hole may experience very strong deviations. Two geometries were separately considered in the recent literature: a source behind the black hole (standard gravitational lensing); a source in front of the black hole (retro-lensing). In this paper we start from the Strong Field Limit approach to recover both situations un

L. Wyrzykowski, A. Udalski, M. Kubiak, M. K. Szymanski

We present new version of the OGLE-II catalog of eclipsing binary stars detected in the Small Magellanic Cloud, based on Difference Image Analysis catalog of variable stars in the Magellanic Clouds containing data collected from 1997 to 2000. We found 1351 eclipsing binary stars in the central 2.4 square degree area of the SMC. 455 stars are newly discovered

T. A. Oosterloo, R. Morganti, B. H. C. Emonts, C. N. Tadhunter

AGN activity is known to drive fast outflows of gas. We report the discovery of fast outflows of neutral gas with velocities over 1000 km/s in a number of radio galaxies. In the best studied object, 3C~293, the kinematical properties of the neutral and ionised outflows are similar, indicating a common origin. Moreover, the outflow appears to be located near

Raffaella Morganti

Radio-loud AGNs can inhabit regions with a very rich ISM. The presence of this rich medium is likely related to the origin and evolution of the host galaxy and of the active nucleus. Recent observations show that a large fraction of radio galaxies contains a significant young stellar population. This supports the idea that mergers are responsible for both th

Soma Manda, Somenath Chakrabarty

The transport properties of dense stellar electron-proton plasma is studied following an exact relativistic formalism in presence of strong quantizing magnetic field. The variation of transport coefficients with magnetic field are found to be insensitive for the field strengths $\leq 10^{17}$G, beyond which all of them abruptly go to zero. As a consequence,

Shiro Hirai

The effect of pre-inflation physics on the power spectrum of scalar perturbations is estimated and there is a possibility that the pre-inflation physics explains the Wilkinson Microwave Anisotropy Probe data if the length of inflation is near 60 e-folds. Considering various pre-inflation models with radiation-dominated or matter-dominated periods before infl

Andrew Cumming

I describe work on two aspects of magnetic field evolution relevant for the &#34;recycling&#34; scenario for making millisecond radio pulsars. First, many of the theoretical ideas for bringing about accretion-induced field decay rely on dissipation of currents in the neutron star crust. I discuss field evolution in the crust due to the Hall effect, and outli

Chang Won Lee, Philip C. Myers, Rene Plume

We present CS(3-2) and DCO+(2-1) observations of 94 starless cores and compare the results with previous CS(2-1) and N2H+(1-0) observations to study inward motions in starless cores. The velocity shifts of the CS(3-2) and (2-1) lines with respect to N2H+ correlate well with each other and have similar distributions. This implies that, in many cores, systemat

S. J. Curran, M. T. Murphy, Y. M. Pihlstroem, J. K. Webb

We have used the Green Bank Telescope (GBT) and Berkeley-Illinois-Maryland Association (BIMA) array to search for redshifted millimetre absorption in a sample of damped Lyman-alpha absorption systems (DLAs). This brings the number of published systems searched from 18 to 30. In 17 cases we reach $3σ$ limits of $τ\leq0.1$, which is a significant improvement o

R. Foot, Z. K. Silagadze

There are three astroparticle physics puzzles which fire the imagination: the origin of the ``Great Positron Producer&#39;&#39; in the galactic bulge, the nature of the gamma-ray bursts central engine and the mechanism of supernova explosions. We show that the mirror matter model has the potential to solve all three of these puzzles in one beautifully simple

Alexey Muranov

The existence of an infinite simple boundedly generated 2-generated group and the existence of a boundedly simple 2-generated group containing a free non-cyclic subgroup are proved.

Daniel Huertas-Hernando, Yu. V. Nazarov

We study the proximity effect in hybrid structures consisting of superconductor and ferromagnetic insulator separated by a normal diffusive metal (S/N/FI structures). These stuctures were proposed to realize the absolute spin-valve effect. We pay special attention to the gaps in the density of states of the normal part. We show that the effect of the ferroma

E. Elizalde, E. J. Ferrer, V. de la Incera

We derive general expressions at the one-loop level for the coefficients of the covariant structure of the neutrino self-energy in the presence of a constant magnetic field. The neutrino energy spectrum and index of refraction are obtained for neutral and charged media in the strong-field limit ($M_{W}\gg \sqrt{B}\gg m_{e},T,μ,| \mathbf{p}| $) using the lowe

M. Loewe, C. Villavicencio

Density and thermal corrections to the mass of the pions are studied in the framework of the SU(2) low energy effective chiral lagrangian, in terms of the isospin chemical potential $μ_\tin{I}$. We concentrate the discussion in the region where the isospin chemical potential (absolute value) becomes bigger than the pion mass at zero temperature and density,

Harald W. Griesshammer

Neutron-deuteron scattering in the context of ``pion-less&#39;&#39; Effective Field Theory at very low energies is investigated to next-to-next-to-leading order. Convergence is improved by fitting the two-nucleon contact interactions to the tail of the deuteron wave-function, a procedure known as Z-parameterisation and extended here to the three-nucleon syst

K. N. Zyablyuk

The difference of vector and axial-vector charged current correlators is analyzed by means of QCD sum rules. The contribution of 10-dimensional 4-quark condensates is calculated and its value is estimated within the framework of factorization hypothesis. It is compared to the result, obtained from operator fit of Borel sum rules in the complex q^2-plane, cal

Kentaro Hori, Johannes Walcher

We study marginal deformations of B-type D-branes in Landau-Ginzburg orbifolds. The general setup of matrix factorizations allows for exact computations of F-term equations in the low-energy effective theory which are much simpler than in a corresponding geometric description. We present a number of obstructed and unobstructed examples in detail, including o

T. Fennell, O. A. Petrenko, B. Fak, S. T. Bramwell

Dy2Ti2O7 has been advanced as an ideal spin ice. We present a neutron scattering investigation of a sample of 162Dy2Ti2O7. The scattering intensity has been mapped in zero applied field in the hhl and hk0 planes at temperatures between 0.05 K and 20 K. The measured diffuse scattering (in the static approximation) has been compared to that predicted by the di

Esteban Moro

We present new numerical schemes to integrate stochastic partial differential equations which describe the spatio-temporal dynamics of reaction-diffusion (RD) problems under the effect of internal fluctuations. The schemes conserve the nonnegativity of the solutions and incorporate the Poissonian nature of internal fluctuations at small densities, their perf

Xiao-Gang He, G. Valencia

Motivated by the E787 and E949 result for K+ -> pi+ nu nu(bar) we examine the effects of a new non-universal right-handed Z&#39; boson on flavor changing processes. We place bounds on the tree-level FCNC from K-K(bar) and B-B(bar) mixing as well as from the observed CP violation in kaon decay. We discuss the implications for K -> pi nu nu(bar), B -> X nu nu(