September 2002 arXiv papers — page 8

C. B. Muratov

We introduce an approximation scheme for the Hodgkin-Huxley model of nerve conductance which allows to calculate both the speed of the traveling pulses and their shape in quantitative agreement with the solutions of the model. We demonstrate that the reduced problem for the front of the traveling pulse admits a unique solution. We obtain an explicit analytic

Adrian Ankiewicz, Ken-ichi Maruno, Nail Akhmediev

Using a direct ansatz approach, we have found a number of zero-velocity analytic solutons of the complex quintic Swift-Hohenberg equation. These find application in assorted optical problems.

Francisco Guil, Manuel Manas, Luis Martinez Alonso

A general scheme for analyzing reductions of Whitham hierarchies is presented. It is based on a method for determining the $S$-function by means of a system of first order partial differential equations. Compatibility systems of differential equations characterizing both reductions and hodograph solutions of Whitham hierarchies are obtained. The method is il

Manuel Manas, Luis Martinez Alonso

A hodograph transformation for a wide family of multidimensional nonlinear partial differential equations is presented. It is used to derive solutions of the heavenly equation (dispersionless Toda equation) as well as a family of explicit ultra-hyperbolic selfdual vacuum spaces admiting only one Killing vector which is not selfdual, we also give the correspo

Dan Haran, Moshe Jarden, Florian Pop

Field Arithmetic studies the interplay between arithmetical properties of fields and their absolute Galois groups. Here we studies fields satisfying local global principles for rational points of varieties and profinite groups satisfying local global principles for solvability of embedding problems.

Timur Oikhberg, Vladimir G. Troitsky

M. Krein proved in 1948 that if T is a continuous operator on a normed space leaving invariant an open cone, then its adjoint T* has an eigenvector. We present generalizations of this result as well as some applications to C*-algebras, operators on l_1, operators with invariant sets, contractions on Banach lattices, the Invariant Subspace Problem, and von Ne

Rafe Mazzeo

The theory of complete surfaces of (nonzero) constant mean curvature in $\RR^3$ has progressed markedly in the last decade. This paper surveys a number of these developments in the setting of Alexandrov embedded surfaces; the focus is on gluing constructions and moduli space theory, and the analytic techniques on which these results depend. The last section

Sergey A. Denisov, Barry Simon

Let $p_n(x)$ be orthogonal polynomials associated to a measure $dμ$ of compact support in $R$. If $E\not\in supp(dμ)$, we show there is a $δ>0$ so that for all $n$, either $p_n$ or $p_{n+1}$ has no zeros in $(E-δ, E+δ)$. If $E$ is an isolated point of $supp(dμ)$, we show there is a $δ$ so that for all $n$, either $p_n$ or $p_{n+1}$ has at most one zero in $(

R. E. Borcherds

A content-free expository article about the monster simple group.

Manfred Schocker

A coplactic class in the symmetric group S_n consists of all permutations in S_n with a given Schensted Q-symbol, and may be described in terms of local relations introduced by Knuth. Any Lie element in the group algebra of S_n which is constant on coplactic classes is already constant on descent classes. As a consequence, the intersection of the Lie convolu

Kazuo Habiro

The main object of study in this paper is the completion Z[q]^N=\varprojlim_n Z[q]/((1-q)(1-q^2)...(1-q^n)) of the polynomial ring Z[q], which arises from the study of a new invariant of integral homology 3-spheres with values in Z[q]^N announced by the author, which unifies all the sl_2 Witten-Reshetikhin-Turaev invariants at various roots of unity. We show

Xinyu He

A sufficient condition is derived for a finite-time $L_2$ singularity of the 3d incompressible Euler equations, making appropriate assumptions on eigenvalues of the Hessian of pressure. Under this condition $\lim_{t \to T_*} \sup | \frac{D ø} {Dt} |_{L_2(\vO)} = \infty$, where $~ \vO \subset \R3$ moves with the fluid. In particular, $|ø|$, $|§_{ij}| , and $|

Miran Cerne

Let S be a bordered Riemann surface with genus g and m boundary components. For a smooth family of smooth Jordan curves in the complex plane parametrized by the boundary of S and such that all curves contain 0 in their interior we show that there exists a holomorphic solution of the corresponding Riemann-Hilbert problem with at most 2g+m-1 zeros on S.

Leila Khatami, Siamak Yassemi

Let $(R,\fm)$ be a commutative Noetherian local ring. Suppose that $M$ and $N$ are finitely generated modules over $R$ such that $M$ has finite projective dimension and such that $\Tor^R_i(M,N)=0$ for all $i>0$. The main result of this note gives a condition on $M$ which is necessary and sufficient for the tensor product of $M$ and $N$ to be a Cohen--Macaula

C. S. Rajan

We generalize a beautiful method of Blasius and Ramakrishnan, that in order to exhibit particular instances of the Langlands functorial correspondence, it is enough to show that the correspondence holds in the semistable case, provided the arithmetic data we are considering is closed with respect to cyclic base change and descent.

David Kazhdan, Alexander Polishchuk

In the first part of this paper we study minimal representations of simply connected simple split groups of type $D_k$ or $E_k$ over local non-archimedian fields. Our main result is an explicit formula for the spherical vectors in these representations. In the case of real and complex groups such a formula was obtained recently in hep-th/0107222. We also use

Gavril Farkas, Mihnea Popa

We prove two statements on the slopes of effective divisors on the moduli space of stable curves of genus g: first that the Harris-Morrison Slope Conjecture fails for g=10 and second, that in order to compute the slope of the moduli space of curves for g\leq 23, one only has to consider the coefficients of the Hodge class and that of the boundary divisor δ_0

Pablo Braz e Silva

We present results concerning resolvent estimates for the linear operator associated with the system of differential equations governing perturbations of the Couette flow. We prove estimates on the L_2 norm of the resolvent of this operator showing this norm to be proportional to the Reynolds number R for a region of the unstable half plane. For the remainin

Eugene Tokarev

To describe a set of functions, which forms a reflexive subspace B of the classical Banach space L a special function that characterizes their average integral growth is introduced. It is shown that this function essentially depends on the geometry of B. By the way, one question of la Vallee Poussin is answered. Also a short proof of the known result about t

Jared Wunsch

Let $X$ be a compact Riemannian manifold with conic singularities, i.e. a Riemannian manifold whose metric has a conic degeneracy at the boundary. Let $Δ$ be the Friedrichs extension of the Laplace-Beltrami operator on $X.$ There are two natural ways to define geodesics passing through the boundary: as ``diffractive'' geodesics which may emanate from

Alessia Cattabriga, Michele Mulazzani

We study the connections among the mapping class group of the twice punctured torus, the cyclic branched coverings of (1,1)-knots and the cyclic presentations of groups. We give the necessary and sufficient conditions for the existence and uniqueness of the n-fold strongly-cyclic branched coverings of (1,1)-knots, through the elements of the mapping class gr

Winfried Bruns, Joseph Gubeladze

Using elementary graded automorphisms of polytopal algebras (essentially the coordinate rings of projective toric varieties) polyhedral versions of the group of elementary matrices and the Steinberg and Milnor groups are defined. They coincide with the usual K-theoretic groups in the special case when the polytope is a unit simplex and can be thought of as c

Louis Funar, Rosa Gini

The cobordism group $N(M^n)$ of codimension-one immersions in the $n$-manifold $M^n$ has a natural filtration induced by any cellular decomposition. The problem addressed in this paper is the explicit computation of the graded group $gr^*N(M^n)$. We introduce some new invariants for immersions enlightening the Atiyah-Hirzebruch spectral sequence associated t

Theodore J. Allen, Costas J. Efthimiou, Donald Spector

We analyze a potential that produces background charges which are automatically quantized. This introduces a new mechanism for charge quantization, although so far it has only been implemented for background charges. We show that this same mechanism can also lead to an alternative means of hiding extra dimensions that is analogous to the Kaluza-Klein approac

Z. F. Ezawa, G. Tsitsishvili, K. Hasebe

Noncommutative geometry governs the physics of quantum Hall (QH) effects. We introduce the Weyl ordering of the second quantized density operator to explore the dynamics of electrons in the lowest Landau level. We analyze QH systems made of $N$-component electrons at the integer filling factor $ν=k\leq N$. The basic algebra is the SU(N)-extended W$_{\infty}$

M. Cvetic, H. Lu, C. N. Pope, K. S. Stelle

We study the linearly-realised worldsheet supersymmetries in the ``massive'' type II light-cone actions for pp-wave backgrounds. The pp-waves have have 16+N_sup Killing spinors, comprising 16 ``standard'' Killing spinors that occur in any wave background, plus N_sup ``supernumerary'' Killing spinors (0\le N_sup \le 16) that occur only

David Nolland

We show how VEV's and condensates can be read off from the Schrödinger wave-functional without further calculation. This allows us to study non-perturbative physics by solving the Schrödinger equation. To illustrate the method we calculate fermion condensates from the exact solution of the Schwinger model, and other (1+1) dimensional models. The chiral c

M. Buchler

We propose a new method to obtain the K -> pi pi amplitude from K -> pi which allows one to fully account for the effects of final state interactions. The method is based on a set of dispersion relations for the K -> pi pi amplitude in which the weak Hamiltonian carries momentum. The soft pion theorem, which relates this amplitude to the K -> pi amplitude, c

Mark G. Alford

I give a survey of recent progress in our understanding of QCD at high density and temperature. I pay particular attention to color superconductivity, applications of lattice gauge theory at nonzero density as well as high temperature, perturbative results at high temperature, and non-equilibrium calculations.

Wojciech Broniowski, Anna Baran, Wojciech Florkowski

Applications of a simple thermal model to ultra-relativistic heavy-ion collisions are presented. We compute abundances of various hadrons, including particles with strange quarks, the pT-spectra, and the HBT radii for the pion. Surprising agreement is found, showing that the thermal approach can be used successfully to understand and describe the RHIC data.

Ja. V. Burdanov, G. V. Efimov

Using a simple relativistic QFT model of scalar fields we demonstrate that the analytic confinement (propagator is an entire function in the complex $p^2$--plane) and the weak coupling constant lead to the Regge behaviour of the two-particle bound states. In QCD we assume that the gluon vacuum is realized by the self-dual homogeneous classical field which is

A. Tounsi, A. Mischke, Krzysztof Redlich

Strangeness enhancement (SE) in heavy ion collisions can be understood in the statistical model on the basis of canonical suppression. In this formulation,SE is a consequence of the transition from canonical to the asymptotic grand canonical limit and is predicted to be a decreasing function of collision energy. This model predictions are consistent with the

Nicola Fabiano

We discuss the theoretical predictions for the two photon decay width of the pseudoscalar etab meson. Predictions from potential models are examined. It is found that various models are in good agreement with each other. Results for etab are also compared with those from Upsilon data through the NRQCD procedure.

J. R. Cudell, E. Martynov, G. Soyez

We show that t-channel unitarity constraints make it possible to obtain the photon-photon cross sections from the photon-proton and proton-proton cross sections, for Q2<150 GeV2. In order to do so, one must postulate the existence of double-pole or triple-pole singularities in the complex j plane.

Ambar Ghosal, Debasish Majumdar

In view of recent neutrino experimental results such as SNO, Super-Kamiokande (SK), CHOOZ and neutrinoless double beta decay $(ββ_{0ν})$, we consider a texture of neutrino mass matrix which contains three parameters in order to explain those neutrino experimental results. We have first fitted parameters in a model independent way with solar and atmospheric n

Debasish Majumdar

We have considered neutralino to be the lightest supersymmetric particle (LSP) in the framework of minimal Anomaly Mediated Supersymmetric (mAMSB) model. We have studied variation of neutralino mass with the supersymmetric parameters. Considering these neutralinos to be the candidates for weakly interacting massive particle (WIMP) or cold dark matter (CDM),

Debasish Majumdar

We consider the lightest Kaluza-Klein particle at N=1 mode (LKP) of universal extra dimension to be the candidate for Dark Matter and predict the detection rates for such particles for Germenium and NaI detectors. We have also calculated the nature of annual modulation for the signals in these two types of detectors for LKP Dark Matter. The rates with differ

Yu. A. Simonov

Basic developments in the analytic study of the QCD vacuum structure and of the QCD spectrum, including glueballs and hybrids are reviewed.

Cheng-Wei Chiang, Zumin Luo, Jonathan L. Rosner

Singly-Cabibbo-suppressed decays of charmed particles governed by the quark subprocesses $c \to s u \bar s$ and $c \to d u \bar d$ are analyzed using a flavor-topology approach, based on a previous analysis of the Cabibbo-favored decays governed by $c \to s u \bar d$. Decays to $PP$ and $PV$, where $P$ is a pseudoscalar meson and $V$ is a vector meson, are c

Quentin Mason, Peter Lepage, Paul Mackenzie, Howard Trottier

We present results from a systematic perturbative investigation of taste-changing in improved staggered quarks. We show one-loop taste-changing interactions can be removed perturbatively by an effective four-quark term and calculate the necessary coefficients.

M. Goeckeler, R. Horsley, D. Pleiter, P. E. L. Rakow

We compute hadron masses and the lowest moments of unpolarized and polarized nucleon structure functions down to pion masses of 300 MeV, in an effort to make unambiguous predictions at the physical light quark mass.

G. Unal

The direct CP violation parameter Re($ε&#39;ε$) has been measured from the decay rates of neutral kaons into two pions using the NA48 detector at the CERN SPS. The 2001 running period was devoted to collecting additional data under varied conditions compared to earlier years (1997-99). The 2001 data yield the result: Re($εε&#39;$)=$(13.7\pm3.1)\times10^{-4}$

C. S. Unnikrishnan, G. T. Gillies

We present constraints from various experimental data that limit any spatial anisotropy of the Gravitational constant to less than a part per billion or even smaller. This rules out with a wide margin the recently reported claim of a spatial anisotropy of G with a diurnal temporal signature.

David Delphenich

The mathematical notion of foliated cobordism is presented, and its relationship to both the motion of extended particles and wave motion is detailed. The fact that wave motion, when represented in such a manner on a four-dimensional spacetime, leads to a reduction of the bundle of linear frames to an SO(2)-principle bundle is demonstrated. Invariants of fol

Sugumi Kanno, Jiro Soda

The low energy effective theory for the Randall-Sundrum two-brane system is investigated with an emphasis on the role of the non-linear radion in the brane world. It is shown that the gravity on the brane world is described by a quasi-scalar-tensor theory with a specific coupling function.

Jiro Soda, Sugumi Kanno

The cosmological perturbation theory is revisited from the holographic point of view. In the case of the single brane model, it turns out that the AdS/CFT correspondence plays an important role. In the case of the two-brane model, it is shown that the effective equations of motion becomes the quasi-scalar-tensor gravity. It is also demonstrated that the radi

Jorge Pullin

Contents: * Community news: Einstein prize update, by Clifford Will World year of physics, by Richard H. Price We hear that... by Jorge Pullin * Research briefs: R-mode epitaph? by John Friedman and Nils Andersson Gravitational waves from bumpy neutron stars, by Ben Owen LIGO science operations begin!, by Gary Sanders * Conference reports: Fourth internation

C. B. Muratov

We develop a theory of the domain patterns in systems with competing short-range attractive interactions and long range repulsive Coulomb interactions. We take an energetic approach, in which patterns are considered as critical points of a mean-field free energy functional. Close to the microphase separation transition, this functional takes on a universal f

Sanjib Sabhapandit

In this thesis, we discuss nonequilibrium ferromagnetic random field Ising model (RFIM) with zero temperature Glauber single spin flip dynamics. We briefly review the hysteresis in ferromagnets and Barkhausen effect. We discuss some earlier results on the zero temperature RFIM. We also discuss some of the equilibrium properties of RFIM. We setup the generati

Henrique J. P. Freire, J. Carlos Egues

Digital Magnetic Heterostructures (DMH) are semiconductor structures with magnetic monolayers. Here we study electronic and magneto-transport properties of shallow modulation-doped (ZnSe/ZnCdSe) DMHs with spin-5/2 Mn impurities. We compare the &#34;reservoir&#34; model, possibly relevant to shallow geometries, to the usual &#34;constant-density&#34; model. O

P. S. Cornaglia, M. F. Laguna

We model a tridimensional vortex system in a sample with square superficial pinning in the top surface and obtain the ground state structures as a function of the sample thickness. Using a simple Frenkel-Kontorova like model and no adjustable parameters, we reproduce the experimental vortex configurations seen in the bottom surface and their range of stabili

E. Artacho, M. Machado, D. Sanchez-Portal, P. Ordejon

The electronic structure of an infinite poly-guanine - poly-cytosine DNA molecule in its dry A-helix structure is studied by means of density-functional calculations. An extensive study of 30 nucleic base pairs is performed to validate the method. The electronic energy bands of DNA close to the Fermi level are then analyzed in order to clarify the electron t

F. Pierre, Norman O. Birge

We have probed the magnetic field dependence of the electron phase coherence time $τ_ϕ$ by measuring the Aharonov-Bohm conductance oscillations of mesoscopic Cu rings. Whereas $τ_ϕ$ determined from the low-field magnetoresistance saturates below 1 K, the amplitude of Aharonov-Bohm $h/e$ oscillations increases strongly on a magnetic field scale proportional t

A. M. Glukhov, A. G. Sivakov, A. V. Ustinov

Measurements of the electrical response of granular Sn-Ge thin films below the superconducting transition temperature are reported. The addition of an external noise to the magnetic field applied to the sample is found to increase the sample voltage response to a small externally applied ac signal. The gain coefficient for this signal and the signal-to-noise

Jan Martinek, Józef Barnas, Gerd Schön, Saburo Takahashi

We show that nonequilibrium spin fluctuations significantly influence the electronic transport in a single-electron transistor, when the spin relaxation on the island is slow compared to other relaxation processes, and when size effects play a role. To describe spin fluctuations we generalize the `orthodox&#39; tunneling theory to take into account the elect

J. -Ch. Anglès d&#39;Auriac, J. -M. Maillard, C. M. Viallet

We classify four-state spin models with interactions along the edges according to their behavior under a specific group of symmetry transformations. This analysis uses the measure of complexity of the action of the symmetries, in the spirit of the study of discrete dynamical systems on the space of parameters of the models, and aims at uncovering solvable on

A. A. Izmalkov, L. A. Openov

Results of tight-binding calculations on metastable spin-polarized carbon clusters C_8 (prismanes) are presented. It is shown that those clusters can form ensembles due to intercluster bonding. The binding energy of a given metastable configuration decreases monotonously with the total spin S, while the activation energy for the decay of a metastable state h

D. I. Tsomokos, C. C. Chong, A. Vourdas

Interfering electrons in a mesoscopic ring are irradiated with both classical and nonclassical microwaves. The average intensity of the charges is calculated as a function of time and it is found that it depends on the nature of the irradiating electromagnetic field. For various quantum states of the microwaves, the electron autocorrelation function is calcu

K. W. Edmonds, K. Y. Wang, R. P. Campion, A. C. Neumann

We show that by annealing Ga1-xMnxAs thin films at temperatures significantly lower than in previous studies, and monitoring the resistivity during growth, an unprecedented high Curie temperature Tc and conductivity can be obtained. Tc is unambiguously determined to be 118 K for Mn concentration x=0.05, 140 K for x=0.06, and 120 K for x=0.08. We also identif

K. Izawa, Y. Nakajima, J. Goryo, Y. Matsuda

The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear ind

Rafael A. Molina, Dietmar Weinmann, Rodolfo A. Jalabert, Gert-Ludwig Ingold

Based on a recent proposal [O.P. Sushkov, Phys. Rev. B 64, 155319 (2001)], we relate the quantum conductance through a sample in which electrons are strongly correlated to the persistent current of a large ring, composed of the sample and a non-interacting lead. A scaling law in the lead length allows to extrapolate to a well-defined value of the conductance

A. L. Chudnovskiy

The current voltage (IV) characteristics for perpendicular transport through two sequentially coupled wires of finite length is calculated analytically. The transport within a Coulomb blockade step is assisted by plasmon resonances that appear as steps in the IV characteristics with positions and heights depending on inter- and intrawire interactions. In par

Rafael A. Molina, Dietmar Weinmann, Rodolfo A. Jalabert

We study the Landau damping of the surface plasmon resonance of metallic nanoparticles embedded in different environments of experimental relevance. Important oscillations of the plasmon linewidth as a function of the radius of the nanoparticles are obtained from numerical calculations based on the time dependent local density approximation. These size-oscil

I. Vilfan, M. Henzler, O. Pfennigstorf, H. Pfnuer

The magnetoconductive properties of ultrathin Pb films deposited on Si(111) are measured and compared with density-functional electronic band-structure calculations on two-dimensional, free-standing, 1 to 8 monolayers thick Pb(111) slabs. A description with free-standing slabs is possible because it turned out that the Hall coefficient is independent of the

V. V. Khovailo, T. Takagi, A. N. Vasil&#39;ev, H. Miki

Order-disorder phase transition in Ni$_{2+x}Mn_{1-x}$Ga Heusler alloys has been studied. It was found that the $L2_1 \to B2^{\prime}$ phase transition in Ni2+xMn1-xGa (x = 0.16 - 0.20) Heusler alloys is of second order and the temperature of this transition decreases with Ni excess.

Anika Kumar, Nilotpal Ghosh, Janhavi P. Joshi, H. L. Bhat

Single crystals of Nd_{1-x}Pb_{x}MnO_{3} with x=0.2 are grown by high temperature solution growth technique using PbO-PbF_{2} flux. Magnetization studies on the samples show a transition to a ferromagnetic state below T_c ~ 125 K and the resistivity measurements show it to be an insulator throughout the temperature range 50 - 300 K. Electron Paramagnetic Res

A. N. Vasil&#39;ev, E. I. Estrin, V. V. Khovailo, A. D. Bozhko

A study of polycrystalline and single crystalline Ni$_{2+x}$Mn$_{1-x}$Ga alloys by means of dilatometric and strain gage techniques shows that large strain can be induced in the temperature range of the martensitic transformation by application of an external magnetic field. The biggest strain induced by magnetic field was observed in the samples of chemical

Boris Kastening

A recent simplified transfer matrix solution of the two-dimensional Ising model on a square lattice with periodic boundary conditions is generalized to periodic-antiperiodic, antiperiodic-periodic and antiperiodic-antiperiodic boundary conditions. It is suggested to employ linear combinations of the resulting partition functions to investigate finite-size sc

Yusuke Wakabayashi, Youichi Murakami, Ichiro Koyama, Tsuyoshi Kimura

Charge and orbital ordering behaviors in the half doped bi-layered compound LaSr2Mn2O7 have been studied by resonant and non-resonant X-ray scattering. Three different order parameters, which correspond to the A-type antiferromagnetic, a charge and an orbital ordered states, were observed by measuring the magnetostriction and the superlattice peaks character

M. B. Hastings, C. J. Olson Reichhardt, C. Reichhardt

We force a single particle through a two-dimensional simulated glass. We find that the particle velocity obeys a robust power law that persists to drives well above threshold. As the single driven particle moves, it induces cooperative distortions in the surrounding medium. We show theoretically that a fracture model for these distortions produces power law

D. J. Priour, H. A. Fertig

Using Ginzburg-Landau theory, we have performed detailed studies of vortices in the presence of artificial defect arrays, for a thin film geometry. We show that when a vortex approaches the vicinity of a defect, an abrupt transition occurs in which the vortex core develops a ``string&#39;&#39; extending to the defect boundary, while simultaneously the superc

Zaher Salman

We calculate the molecular-spin ($S$), temperature ($T$), and field ($H$) dependence of $1/T_1$ for a local magnetic probe coupled to an isotropic high spin molecule, based on spin-phonon interaction. We compare the calculation to recent NMR and $μ$SR experiments in CrCu$_6$ ($S = 9/2$), CrNi$_6$ ($S = 15/2$) and CrMn$_6$ ($S = 27/2$). Although we can accoun

R. Roussev, A. J. Millis

A realistic theory of the quantum paraelectric - ferroelectric transition is presented, involving parameters determined from band calculations and a renormalization group treatment of critical fluctuations. The effects of reduced dimensionality and deviations from cubic symmetry are determined. Expressions for the pressure dependence of the critical temperat

David Charbonneau

The rich wealth of observational data, and matching theoretical investigations, of the transiting planet of HD209458 stands in sharp contrast to systems for which only the radial velocity orbit is known. In this paper, I summarize the current status of these observations, and motivate a variety of projects that should be accessible with existing instruments.

N. Mirabal, F. Paerels, J. P. Halpern

We present high-resolution X-ray spectroscopy of GRB 020405 obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory starting 1.68 days after the burst. The spectrum appears featureless, with no evidence for emission lines, absorption edges, or narrow radiative recombination continua. The continuum can be

J. Craig Wheeler

This Resource Letter provides a guide to the literature on the observations of supernovae and the theory of their explosion mechanisms. Journal articles and books are cited for the following topics: observations of the spectra, spectropolarimetry, and light curves of supernovae of various types, theory of thermonuclear explosions, core collapse, and radioact

M. Geha, C. Alcock, R. A. Allsman, D. R. Alves

We present 47 spectroscopically-confirmed quasars discovered behind the Magellanic Clouds identified via photometric variability in the MACHO database. Thirty-eight quasars lie behind the Large Magellanic Cloud and nine behind the Small Magellanic Cloud, more than tripling the number of quasars previously known in this region. The quasars cover the redshift

Dimitri A. Gadotti, Ronaldo E. de Souza

To further enhance our understanding on the formation and evolution of bars in lenticular (S0) galaxies, we are undertaking a detailed photometric and spectroscopic study on a sample of 22 objects. Here we report the results of a 2D structural analysis on two barred face-on S0&#39;s, which indicate that presently these galaxies do not possess disks. We discu

Robert Stein, Aake Nordlund

We simulate convection near the solar surface, where the continuum optical depth is of order unity. Hence, to determine the radiative heating and cooling in the energy conservation equation, we must solve the radiative transfer equation (instead of using the diffusion or optically thin cooling approximations). A method efficient enough to calculate the radia

Chyng-Lan Liang, John A. Rice, Imke de Pater, Charles Alcock

The Taiwanese-American Occultation Survey (TAOS) will detect objects in the Kuiper Belt, by measuring the rate of occultations of stars by these objects, using an array of three to four 50cm wide-field robotic telescopes. Thousands of stars will be monitored, resulting in hundreds of millions of photometric measurements per night. To optimize the success of

S. B. Pandey, G. C. Anupama, R. Sagar, D. Bhattacharya

We present the $UBVR_cI_c$ broad band optical photometry of the Type Ic supernova SN 2002ap obtained during 2002 February 06 -- March 23 in the early decline phases and also later on 2002 15 August. Combining these data with the published ones, the general light curve development is studied. The time and luminosity of the peak brightness and the peak width a

A. D. Erlykin, A. A. Lagutin, A. W. Wolfendale

The problem of the origin of cosmic rays in the shocks produced by supernova explosions at energies below the so called &#39;knee&#39; (at ~3*10$^6$ GeV) in the energy spectrum is addressed, with special attention to the propagation of the particles through the inhomogenious interstellar medium and the need to explain recent anisotropy results, [1]. It is sh

L. P. L. Colombo, S. A. Bonometto

Anisotropy data analysis leaves a significant degeneracy between primeval spectral index (n_s) and cosmic opacity to CMB photons (τ). Low--l polarization measures, in principle, can remove it. We perform a likelihood analysis to see how cosmic variance possibly affects such a problem. We find that, for a sufficiently low noise level (σ_{pix}) and if τis not

Ruth A. Daly, E. J. Guerra

Fanaroff-Riley type IIb (FR IIb) radio galaxies provide a modified standard yardstick that allows constraints to be placed on global cosmological parameters. A sample of 20 FR IIb radio galaxies with redshifts between 0 and 2 are compared with the parent population of 70 radio galaxies to determine the coordinate distance to each source. The coordinate-dista

D. Mesa, C. Baccigalupi, G. De Zotti, L. Gregorini

We investigate the statistical properties of the polarized emission of extragalactic radio sources and estimate their contribution to the power spectrum of polarization fluctuations in the microwave region. The basic ingredients of our analysis are the NVSS polarization data, the multifrequency study of polarization properties of the B3-VLA sample (Mack et a

V. Bozza, L. Mancini

Many binary systems are in a state of strong interaction, where mass exchanges, accretion disks, common envelopes provide circumstellar matter which can have significant effects in microlensing light curves of background sources. Such chromatic absorption effects provide very interesting information on the nature of this diffuse matter and the physics of the

L. Foschini, L. C. Ho, N. Masetti, M. Cappi

We report the identification of the optical and radio counterparts of the ultraluminous X-ray (ULX) source XMMU J124825.9+083020 (NGC4698-ULX1). The optical spectrum taken with the VLT yields a redshift of z=0.43, which implies that the ULX is not associated with the nearby galaxy NGC4698. The spectral energy distribution calculated from the available data i

L. A. Popa, C. Burigana, N. Mandolesi

We consider the effect of the violation of the equivalence principle (VEP) by the massive neutrino component on the Cosmic Microwave Background angular power specrum. We show that in the presence of adiabatic and isocurvature primordial density perturbations the Planck surveyor can place limits on the maximal VEP by the massive neutrino component at the leve

Takashi Tsuji

We detected the H2O 6.3 micron bands in more than 30 normal red giants stars from K5III to M8III as well as in some early M supergiants on the SWS spectra retrieved from the ISO Data Archive. This result, however, shows serious inconsistency with the present model photospheres which predict H2O only in the latest M (super)giant stars. Also H2O was once disco

P. R. Young, G. Del Zanna, E. Landi, K. P. Dere

The CHIANTI atomic database contains atomic energy levels, wavelengths, radiative transition probabilities and electron excitation data for a large number of ions of astrophysical interest. Version 4 has been released, and proton excitation data is now included, principally for ground configuration levels that are close in energy. The fitting procedure for e

S. Van Eck, A. Jorissen

The properties of the few symbiotic stars detected among the 66 binary S stars from the Henize sample are discussed. Two stars (Hen 18 and Hen 121) exhibit both a strong blue-violet continuum and strong H_alpha emission (FWHM of 70 km/s), whereas Hen 134 and 137 exhibit weak H_alpha emission. The H_alpha profiles are typical of non-dusty symbiotic stars belo

Y. Sato, L. L. Cowie, K. Kawara, Y. Taniguchi

Faint submillimeter sources detected with the Submillimeter Common-User Bolometer Array on the James Clerk Maxwell Telescope have faced an identification problem due to the telescope&#39;s broad beam profile. Here we propose a new method to identify such submillimeter sources with a mid-infrared image having a finer point spread function. The Infrared Space

Christopher M. Hirata, Uros Seljak

Future experiments will produce high-resolution temperature maps of the cosmic microwave background (CMB) and are expected to reveal the signature of gravitational lensing by intervening large-scale structures. We construct all-sky maximum-likelihood estimators that use the lensing effect to estimate the projected density (convergence) of these structures, i

M. T. Murphy, J. K. Webb, V. V. Flambaum, S. J. Curran

We present a short review of the current quasar (QSO) absorption line constraints on possible variation of the fine structure constant, alpha = e^2/(hbar*c). Particular attention is paid to recent optical Keck/HIRES spectra of 49 absorption systems which indicate a smaller alpha in the past (Murphy et al. 2001, Webb et al. 2001). Here we present new prelimin

K. Okumura, A. Asahara, G. V. Bicknell, P. G. Edwards

We have observed Markarian 421 in January and March 2001 with the CANGAROO-II imaging Cherenkov telescope during an extraordinarily high state at TeV energies. From 14 hours observations at very large zenith angles, $\sim70^\circ$, a signal of 298 $\pm$ 52 gamma-ray--like events (5.7 $σ$) was detected at $E>10$ TeV, where a higher sensitivity is achieved tha

Martin Makler, Sergio Quinet de Oliveira, Ioav Waga

We explore the implications of type Ia supernovae (SNIa) observations on flat cosmological models whose matter content is an exotic fluid with equation of state, p=-M^(4(a+1))/rho^a. In this scenario, a single fluid component may drive the Universe from a nonrelativistic matter dominated phase to an accelerated expansion phase behaving, first, like dark matt

Soma Mandal, Somenath Chakrabarty

Following the recent ideas of Dryzek, Kato, Muñoz and Singleton \cite{R1} (henceforth we call this paper as R1), that the composite system consisting of an electron along with its screened electric field and within the sphere of influence, the trapped magnetic field of white dwarf can behave like a boson, we have argued that such an exotic transition (bosoni

Vladimir Ya. Kravchenko, Emmanuel I. Rashba

A theory of spin injection across a ballistic ferromagnet-semiconductor-ferromagnet junction is developed for the Boltzmann regime. Spin injection coefficient $γ$ is suppressed by the Sharvin resistance of the semiconductor $r_N^*=(h/e^2)(π^2/S_N)$, where $S_N$ is the Fermi-surface cross-section. It competes with the diffusion resistances of the ferromagnets

Antonio S. de Castro

The problem of confinement of fermions in 1+1 dimensions is approached with a linear potential in the Dirac equation by considering a mixing of Lorentz vector and scalar couplings. Analytical bound-states solutions are obtained when the scalar coupling is of sufficient intensity compared to the vector coupling.

Yuji Satoh, Jan Troost

We study aspects of the propagation of strings on BTZ black holes. After performing a careful analysis of the global spacetime structure of generic BTZ black holes, and its relation to the geometry of the SL(2,R) group manifold, we focus on the simplest case of the massless BTZ black hole. We study the SL(2,R) Wess-Zumino-Witten model in the worldsheet minis