August 2000 arXiv papers — page 25

N. Mae, S. Iida

We study S-matrix correlations for random matrix ensembles with a Hamiltonian which is the sum of a given deterministic part and of a random matrix with a Gaussian probability distribution. Using Efetov's supersymmetry formalism, we show that, in the limit of infinite matrix size of the Hamiltonian, correlation functions of S-matrix elements are universa

D. R. Matravers, J. Triginer

We provide a covariant and gauge-invariant approach to the question of how a first order pressure can be incorporated self-consistently in a cosmological scenario. The approximation is relevant, in the linear regime, to weakly self-interacting or warm dark matter models. We also derive number density fluctuations in which new modes appear because the number

S. N. Molotkov, S. S. Nazin

A simple proof of the unconditional security of a relativistic quantum cryptosystem based on orthogonal states is proposed. Restrictions imposed by special relativity allow to substantially simplify the proof compared with the non-relativistic cryptosystems involving non-orthogonal states. Important for the proposed protocol is the spatio-temporal structure

Ikuo Ichinose, Keiichi Nagao

In the previous paper we developed a strong-coupling expansion for the lattice QCD with the overlap fermions and showed that Lüsher's "extended" chiral symmetry is spontaneously broken in some parameter region of the overlap fermions. In this paper, we derive a low-energy effective action of hadrons and show that there exist quasi-Nambu-Goldstone

Scott A. Hill, Gene F. Mazenko

We propose a nonlinear hydrodynamical model of granular materials. We show how this model describes the formation of a sand pile from a homogeneous distribution of material under gravity, and then discuss a simulation of a rotating sandpile which shows, in qualitative agreement with experiment, a static and dynamic angle of repose.

C. King, M. B. Ruskai

In this paper, we consider the minimal entropy of qubit states transmitted through two uses of a noisy quantum channel, which is modeled by the action of a completely positive trace-preserving (or stochastic) map. We provide strong support for the conjecture that this minimal entropy is additive, namely that the minimum entropy can be achieved when product s

Valery I. Rupasov

In the quantum process of stimulated Raman scattering (SRS), a laser photon propagating in a resonance medium undergoes multifold conversions into a Stokes photon and back. The nontrivial ``cooperative'' behavior of the Stokes component of light transmitted through the medium is proven to be completely determined by the interference of scattering amp

Lucien Hardy, David D. Song

We find the optimal universal way of manipulating a single qubit, |psi(theta,phi)>, such that (theta,phi)->(theta-k,phi-l). Such optimal transformations fall into two classes. For 0 =< k =< pi/2 the optimal map is the identity and the fidelity varies monotonically from 1 (for k=0) to 1/2 (for k=pi/2). For pi/2 =< k =< pi the optimal map is the universal-NOT

Wolf von Klitzing, Romain Long, Vladimir S. Ilchenko, Jean Hare

We have tuned the whispering gallery modes of a fused silica microresonator over nearly 1 nm at 800 nm, i.e. over 0.5 FSR or 10^6 linewidths of the resonator. This has been achieved by a new method based on the stretching of a two-stem microsphere. The devices described below will permit new Cavity-QED experiments with this high-Q optical resonator when it i

Thomas Ederth

Using a template-stripping method, macroscopic gold surfaces with root-mean-square (rms) roughness less than 0.4 nm have been prepared, making them useful for studies of surface interactions in the nanometer range. The utility of such substrates is demonstrated by measurements of the Casimir force at surface separations between 20 and 100 nm, resulting in go

L. Aphecetche, H. Delagrange, D. G. d&#39;Enterria, M. Le Guay

The design of a detector based on MICROMEGAS (MICRO MEsh GAseous Structure) technology is presented. Our detector is characterized by a large active area of 398(\times)281 mm(^{2}), a pad read-out with 20(\times)22 mm(^{2}) segmentation, and an uniform amplification gap obtained by insulating spacers (100 (μ)m high and 200 (μ)m in diameter). The performances

P. Stevenson, M. R. Strayer, J. Rikovska Stone

We present calculations of ground state properties of spherical, doubly closed-shell nuclei from $^{16}$O to $^{208}$Pb employing the techniques of many-body perturbation theory using a separable density dependent monopole interaction. The model gives results in Hartree-Fock order which are of similar quality to other effective density-dependent interactions

M. Latapy, H. D. Phan

In this paper, we study a famous discrete dynamical system, the Chip Firing Game, used as a model in physics, economics and computer science. We use order theory and show that the set of reachable states (i.e. the configuration space) of such a system started in any configuration is a lattice, which implies strong structural properties. The lattice structure

Jerzy F. Plebanski, Maciej Przanowski, Francisco J. Turrubiates

It is shown that the isomorphism between the generalized Moyal algebra and the matrix algebra follows in a natural manner from the generalized Weyl quantization rule and from the well known matrix representation of the destruction and creation operators.

N. P. Landsman

A theorem of Muhly-Renault-Williams states that if two locally compact groupoids with Haar system are Morita equivalent, then their associated convolution C*-algebras are strongly Morita equivalent. We give a new proof of this theorem for Lie groupoids. Subsequently, we prove a counterpart of this theorem in Poisson geometry: If two Morita equivalent Lie gro

Ola Bratteli, Palle E. T. Jorgensen, Ki Hang Kim, Fred Roush

The notion of isomorphism of stable AF-C*-algebras is considered in this paper in the case when the corresponding Bratteli diagram is stationary, i.e., is associated with a single square primitive nonsingular incidence matrix. C*-isomorphism induces an equivalence relation on these matrices, called C*-equivalence. We show that the associated isomorphism equi

Mukul Patel

This is a research announcement on what is best termed `nonlocal&#39; methods in mathematics. (This is not to be confused with global analysis.) The nonlocal formulation of physics in \cite{principia} points to a fresh viewpoint in mathematics: Nonlocal viewpoint. It involves analyzing objects of geometry and analysis using nonlocal methods, as opposed to th

Michael T. Lacey

The bilinear maximal operator defined below maps $L^p\times L^q$ into $L^r$ provided $1<p,q<\zI$, $1/p+1/q=1/r$ and $2/3<r\le1$. $$ Mfg(x)=\sup_{t>0}\frac1{2t}\int_{-t}^t\abs{f(x+y)g(x-y)} dy.$$ In particular $Mfg$ is integrable\thinspace if $f$ and $g$ are square integrable, answering a conjecture posed by Alberto Calderón.

Wadim Zudilin

We study the arithmetic property which allows to sharpen number-theoretic estimates. Previous results on this property are, as a rule, quantitive. The application of our general qualitive theorems to generalized hypergeometric functions extends the set of irrational numbers which are the values of these functions.

Wayne Rossman, Masaaki Umehara, Kotaro Yamada

A complete surface of constant mean curvature 1 (CMC-1) in hyperbolic 3-space with constant curvature -1 has two natural notions of &#34;total curvature&#34;-- one is the total absolute curvature which is the integral over the surface of the absolute value of the Gaussian curvature, and the other is the dual total absolute curvature which is the total absolu

Klaus Mohnke

We prove (a weak version of) Arnold&#39;s Chord Conjecture using Gromov&#39;s ``classical&#39;&#39; idea in to produce holomorphic disks with boundary on a Lagrangian submanifold.

Astrid an Huef, Dana P. Williams

We characterize the ideal of continuous-trace elements in a separable transformation-group $C^{*}$-algebra $C_0(X)\times G$. In addition, we identify the largest Fell ideal, the largest liminal ideal and the largest postliminal ideal.

Hitoshi Nishino

We present a Lorentz invariant lagrangian formulation for a supersymmetric Yang-Mills vector multiplet in eleven dimensions (11D). The Lorentz symmetry is broken at the field equation level, and therefore the breaking is spontaneous, as in other formulations of supersymmetric theories in 12D or higher dimensions. We introduce a space-like unit vector formed

Saurya Das, Robert B. Mann

We compute the conserved charges for Kerr anti-de Sitter spacetimes in various dimensions using the conformal and the counterterm prescriptions. We show that the conserved charge corresponding to the global timelike killing vector computed by the two methods differ by a constant dependent on the rotation parameter and cosmological constant in odd spacetime d

Rui Neves

The renormalization group flow in the theory space of a BRST invariant string $σ$-model is investigated. For the open bosonic string the non-perturbative off-shell effective action and its gauge symmetry properties are determined from $β$-functions defined by the local Weyl anomaly. The interactions are shown to explicitly break the free theory BRST invarian

G. Sartori, G. Valente

Invariant functions under the transformations of a compact linear group $G$ acting in $\real^n$ can be expressed in terms of functions defined in the orbit space of $G$. We develop a method to determine the isotropy classes of the orbit spaces of all the real linear groups whose integrity bases (IB) satisfy only one independent relation. The method is tested

C. Bizdadea, L. Saliu, S. O. Saliu

Chern-Simons couplings between Yang-Mills gauge fields and an abelian 2-form are derived by means of cohomological arguments.

A. M. Ignatov, V. P. Poponin

The energy-momentum conservation law is used to investigate the interaction of pulses in the framework of nonlinear electrodynamics with Lorentz-invariant constitutive relations. It is shown that for the pulses of the arbitrary shape the interaction results in phase shift only.

Hiroyuki Takata

We consider electric-magnetic duality(S-duality) in IIB matrix model with a D3-brane background. We propose the duality transformation by considering that of noncommutative Yang-Mills theory(NCYM) in four dimension. NCYM derived from the matrix model has a Yang-Mills coupling related to the noncommutativity of the spacetime. We argue that open strings bits a

Helen R. Quinn, Thomas Schietinger, Joao P. Silva, Arthur E. Snyder

We suggest a novel method to determine the sign of cos(2 beta) in the decays B --> psi K, by creating interference between KL and KS final states via ``regeneration,&#39;&#39; that is propagation through a matter target region to convert some KL to KS. The determination of this quantity resolves an ambiguity between beta and (90o - beta) that remains after t

L. Lavoura, W. Grimus

We enlarge the lepton sector of the Standard Model by adding to it two right-handed neutrino singlets, and propose a model based on the seesaw mechanism and on the lepton number $\bar L = L_e - L_μ- L_τ$. The model is innovative from the theoretical point of view in that the $\bar L$-invariant mass term of the right-handed neutrinos is associated with the la

V. Barger, B. Kayser, J. Learned, T. Weiler

In light of recent Super-Kamiokande data and global fits that seem to exclude both pure ν_μ\to ν_s oscillations of atmospheric neutrinos and pure ν_e \to ν_s oscillations of solar neutrinos (where ν_s is a sterile neutrino), we reconsider four-neutrino models to explain the LSND, atmospheric, and solar neutrino oscillation indications. We argue that the sola

K. Dick, M. Freund, P. Huber, M. Lindner

We compare the generic physics potential of various combinations of conventional Wide Band or Neutrino Factory Beams with different detectors to determine several oscillation parameters in long baseline experiments. For each combination of beam and detector we show the precision which can be obtained for the leading oscillation parameters $\dm{31}$ and $\sin

Zhang Chen

An overview of the current status of and possible future theoretical, phenomenological and experimental studies of DVCS and SPD&#39;s is presented.

M. Kuze, S. Lola, E. Perez, B. Allanach

We summarize the experimental and theoretical results presented in the &#34;Physics at the Highest Q^2 and p^2_t&#34; working group at the DIS 2000 Workshop. High Q^2 and p^2_t processes measured at current and future colliders allow to improve our knowledge of Standard Model (SM) physics, by providing precise measurements of the SM parameters and, consequen

P. Christova, M. Jack, S. Riemann, T. Riemann

The past ten years of physics with e+e- colliding experiments at LEP and SLAC have shown the success of these experiments on not only impressively proving the theoretical predictions of the Standard Model (SM), but also to help provide stringent bounds on physics beyond the SM. With this experience in mind, there appear two equally fascinating opportunities

Alec J. Schramm, Benjamin Svetitsky

We offer the Skyrme model on a lattice as an effective field theory - fully quantized - of baryon-meson interactions at temperatures below the chiral phase transition. We define a local topological density that involves the volumes of tetrahedra in the target space S^3 and we make use of Coxeter&#39;s formula for the Schlafli function to implement it. This p

Ying Chen, Bing He, He Lin, Ji-Min Wu

We calculated the SU(2) gluon propagator in Landau gauge on an anisotropic coarse lattice with the improved action. The standard and the improved scheme are used to fix the gauge in this work. Even on the coarse lattice the lattice gluon propagator can be well described by a function of the continuous momentum. The effect of the improved gauge fixing scheme

K. Eitel

The neutrino experiment KARMEN at the beam stop neutrino source ISIS investigates the oscillation channel numubar->nuebar in the appearance mode by looking for p(nuebar,e+)n reactions. An analysis of data collected from February 1997 through March 2000 with the KARMEN2 experimental setup reveals 11 candidate events in good agreement with the background expec

M. Latapy, R. Mantaci, M. Morvan, H. D. Phan

SPM (Sand Pile Model) is a simple discrete dynamical system used in physics to represent granular objects. It is deeply related to integer partitions, and many other combinatorics problems, such as tilings or rewriting systems. The evolution of the system started with n stacked grains generates a lattice, denoted by SPM(n). We study here the structure of thi

Daniel T. Simon, Michael R. Geller

We investigate the electron population dynamics in an ensemble of nearly isolated insulating nanoparticles, each nanoparticle modeled as an electronic two-level system coupled to a single vibrational mode. We find that at short times the ensemble-averaged excited-state population oscillates but has a decaying envelope. At long times, the oscillations become

C. Schonenberger, A. Bachtold

Jeong-O Lee et al. [Phy. Rev. B, 61, R16 362 (2000)] reported magnetoresistance and differential conductance measurements of multiwalled carbon nanotubes. The observed aperiodic conductance fluctuations and the negative magnetoresistance was interpreted to originate exclusively from changes in the density of states at the Fermi energy. We show that this inte

Thereza Paiva, R. T. Scalettar, Carey Huscroft, A. K. McMahan

Local moment formation driven by the on--site repulsion $U$ is one of the most fundamental features in the Hubbard model. At the simplest level, the temperature dependence of the local moment is expected to have a single structure at $T \sim U$, reflecting the suppression of the double occupancy. In this paper we show new low temperature Quantum Monte Carlo

Charles Reichhardt, Niels Gronbech-Jensen

We study vortex states and dynamics in 2D superconductors with periodic pinning at fractional sub-matching fields using numerical simulations. For square pinning arrays we show that ordered states form at 1/1, 1/2, and 1/4 filling fractions while only partially ordered states form at other filling fractions, such as 1/3 and 1/5, in agreement with recent imag

S. J. Papadakis, E. P. De Poortere, M. Shayegan

We study two dimensional hole systems confined to GaAs quantum wells grown on the (311)A surface of GaAs substrates. Such samples exhibit an in-plane mobility anisotropy. At constant 2D hole density, we vary the symmetry of the quantum well potential and measure the temperature dependence of the resistivity along two different current directions, in a regime

Onuttom Narayan

It is demonstrated that the renormalization group (RG) flows of depinning transitions do not depend on whether the driving force or the system velocity is kept constant. This allows for a comparison between RG results and corresponding self-organized critical models. However, close to the critical point, scaling functions cross over to forms that can have si

A. O. Parry, E. D. Macdonald, C. Rascon

We consider the finite-size scaling of equilibrium droplet shapes for fluid adsorption (at bulk two-phase co-existence) on heterogeneous substrates and also in wedge geometries in which only a finite domain $Λ_{A}$ of the substrate is completely wet. For three-dimensional systems with short-ranged forces we use renormalization group ideas to establish that b

Gunther Lang, Ulrich Weiss

We study nonequilibrium transport and noise in a generic dissipative tight-binding model. Within a real-time path integral approach, we derive formally exact series expressions in the number of tunneling events for the noise valid for arbitrary bias, frequency and temperature. At zero temperature, the low-frequency noise can be summed in analytic form. The r

G. Khaliullin, S. Maekawa

We present a theory of spin and orbital states in Mott insulator $LaTiO_3$. The spin-orbital superexchange interaction between $d^1(t_{2g})$ ions in cubic crystal suffers from a pathological degeneracy of orbital states at classical level. Quantum effects remove this degeneracy and result in the formation of the coherent ground state, in which the orbital mo

R. Moradian, J. F. Annett, B. L. Gyorffy, G. Litak

We have studied the effects of strong impurity scattering on disordered superconductors beyond the low impurity concentration limit. By applying the full CPA to a superconductiong A-B binary alloy, we calculated the fluctuations of the local order parameters $Δ_{A}, Δ_{B}$ and charge densities, $n_{A}, n_{B}$ for weak and strong on site disorder. We find tha

I. K. Yanson

The superconducting energy gap and quasiparticle density of states (DOS) is measured by means of Andreev-reflection spectroscopy in normal metal - superconductor point contacts. It is found that both in paramagnetic and in antiferromagnetically ordered states (Tm- and Dy-compounds) the DOS has the BCS-like form while in Er- the dip in the temperature depende

Guo-meng Zhao, D. J. Kang, W. Prellier, M. Rajeswari

Oxygen-isotope effects on the intrinsic resistivity have been studied in high-quality epitaxial thin films of La_{0.75}Ca_{0.25}MnO_{3} and Nd_{0.7}Sr_{0.3}MnO_{3}. We found that the residual resistivity ρ_{o} increases by about 15(3)% upon replacing ^{16}O by ^{18}O. This provides strong evidence for the presence of small or intermediate-size polarons in th

Gianpaolo Valente

We consider the problem of the determination of the isotropy classes of the orbit spaces of all the real linear groups, with three independent basic invariants satisfying only one independent relation. The results are obtained in the $\hat P$-matrix approach solving a universal differential equation ({\em master equation}) which involves as free parameters o

Zhi-Feng Huang, Sorin Solomon

We study by theoretical analysis and by direct numerical simulation the dynamics of a wide class of asynchronous stochastic systems composed of many autocatalytic degrees of freedom. We describe the generic emergence of truncated power laws in the size distribution of their individual elements. The exponents $α$ of these power laws are time independent and d

J. -P. Martikainen

In this paper we study the properties of Bose-Einstein condensates in shallow traps. We discuss the case of a Gaussian potential, but many of our results apply also to the traps having a small quadratic anharmonicity. We show the errors introduced when a Gaussian potential is approximated with a parabolic potential, these errors can be quite large for realis

Francesco Sciortino, Walter Kob

We show that the prediction of mode-coupling theory for a model of a network-forming strong glass-former correctly describes the wave-vector dependence of the Debye-Waller factor. To obtain a good description it is important to take into account the triplet correlation function c_3, which we evaluate from a computer simulation. Our results support the possib

N. Kumar

Quantum Zeno Effect (QZE) is the suppression of the inter-subspace transition by a relatively fast intra-subspace decoherence. Earlier, we had proposed a QZE-based mechanism for the temperature-dependent normal-state c-axis resistivity of the layered high-T$_c$ cuprate superconductors in which the single-particle inter-layer tunneling is blocked by the stron

Mauro Copelli, Katja Lindenberg

We report results on a model of two coupled oscillators that undergo periodic parametric modulations with a phase difference $θ$. Being to a large extent analytically solvable, the model reveals a rich $θ$ dependence of the regions of parametric resonance. In particular, the intuitive notion that anti-phase modulations are less prone to parametric resonance

Robert S. Maier, D. L. Stein

We treat the noise-activated escape from a one-dimensional potential well of an overdamped particle, to which a periodic force of fixed frequency is applied. We determine the boundary layer behavior, and the physically relevant length scales, near the oscillating well top. We show how stochastic behavior near the well top generalizes the behavior first deter

Alberto D. Bolatto, James M. Jackson, Kathleen E. Kraemer, Xiaolei Zhang

We report the first detection of [CI] (3P1-3P0) emission at 609 um in a region of the Small Magellanic Cloud (N27). Environments poor in heavy elements and dust such as the SMC are thought to be dominated by photodissociation regions. This is the lowest metallicity source where submillimeter neutral carbon emission has been detected. Studying the [CI]/CO int

Andrea N. Lommen, Alex Zepka, Donald C. Backer, Maura McLaughlin

We report the discovery of pulsars J0030+0451, J0711+0931, and J1313+0931 that were found in a search of 470 square degrees at 430 MHz using the 305m Arecibo telescope. The search has an estimated sensitivity for long period, low dispersion measure, low zenith angle, and high Galactic latitude pulsars of ~1 mJy, comparable to previous Arecibo searches. Spin

S. Heinz, M. A. Nowak

We present archival RXTE and simultaneous ASCA data of the eclipsing low mass X-ray binary (LMXB) X 1822-371. Our spectral analysis shows that a variety of simple models can fit the spectra relatively well. Of these models, we explore two in detail through phase resolved fits. These two models represent the case of a very optically thick and a very optically

Massimo Marengo, Ray Jayawardhana, Giovanni G. Fazio, William F. Hoffmann

Most, if not all, stars are now believed to produce energetic outflows during their formation. Yet, almost 20 years after the discovery of bipolar outflows from young stars, the origins of this violent phenomenon are not well understood. One of the difficulties of probing the outflow process, particularly in the case of massive embedded stars, is a deficit o

Sidney van den Bergh, Judith G. Cohen, David W. Hogg, Roger Blandford

Morphological classifications are reported for Hubble Space Telescope (HST) images of 241 galaxies in the Hubble Deep Field (HDF) and its Flanking Fields (FF) with measured redshifts in the interval 0.25 < z < 1.2, drawn from a magnitude-limited redshift survey to R = 24.0. The galaxies are divided into three groups with redshifts in the intervals [0.25,0.6]

R. F. Stein, Å. Nordlund

Solar p-mode oscillations are excited by the work of stochastic, non-adiabatic, pressure fluctuations on the compressive modes. We evaluate the expression for the radial mode excitation rate derived by Nordlund and Stein (Paper I) using numerical simulations of near surface solar convection. We first apply this expression to the three radial modes of the sim

Francesco Sylos Labini, Andrea Gabrielli

We present a brief introduction to the statistical properties of systems with large fluctuations. We point out that for such systems the relevant statistical quantities are scaling exponents and the nature of fluctuations is completely different from the one belonging to system with small fluctuations. We then propose two test to be performed on galaxy count

Christopher F. McKee

Polytropic models are reasonably successful in acounting for the observed features of molecular clouds. Multi-pressure polytropes include the various pressure components that are important in molecular clouds, whereas composite polytropes provide a representation for the core halo structure. Small, very dense (n~10^{11} cm^{-3}) molecular clouds have been pr

Patrick McDonald, Jordi Miralda-Escude

We use the redshift evolution of the lyman-alpha forest mean transmitted flux at z>2.5 to infer the evolution of the intensity of the ionizing background, using theoretical predictions for the density distribution of the intergalactic gas giving rise to the lyman-alpha forest. The proper background intensity declines gradually with redshift, decreasing by a

R. J. Wilman, R. M. Johnstone, C. S. Crawford

We present near-infrared spectra of seven radio-loud quasars with a median redshift of 2.1, five of which were previously known to have Ly alpha nebulae. Extended [OIII]5007 and H alpha emission are evident around six objects, at the level of a few times 1E-16 erg/cm^2/arcsec^2/s within 2 arcsec of the nucleus (16 kpc in the adopted cosmology). Nuclear [OII]

John R. dickel, Richard G. Strom, D. K. Milne

G315.4-2.3 is an extended shell supernova remnant (SNR) with some characteristics of evolutionarily young remnants and some of older ones. To further elucidate some of its characteristics, we present imaging and polarimetry of this SNR at a frequency of 1.34 GHz with a resolution of 8 arcsec made with the Australia Telescope Compact Array. The indicators of

Tsafrir S. Kolatt, Ofer Lahav

A combined sample of 79 high and low redshift supernovae Ia (SNe) is used to set constraints on the degree of anisotropy in the Universe out to $z\simeq1$. First we derive the global most probable values of matter density $Ω_M $, the cosmological constant $Ω_Λ$, and the Hubble constant $H_0$, and find them to be consistent with the published results from the

Moshe Carmeli

The early stage of the Universe is discussed and the time lengths of its first six days, as well as its age, are given. There seems to be no contradiction with the Bible&#39;s ascertain that the Universe was created in six days.

D. R. Marlow, D. Rusin, M. Norbury, N. Jackson

We present the discovery of CLASS B0739+366, a new gravitational lens system from the Cosmic Lens All-Sky Survey. Radio imaging of the source with the Very Large Array (VLA) shows two compact components separated by $0\farcs54$, with a flux density ratio of $\sim$ 6:1. High-resolution follow-up observations using the Very Long Baseline Array (VLBA) at 1.7 GH

M. Cervino, V. Luridiana, F. J. Castander

The stochastic nature of the IMF in young stellar clusters implies that clusters of the same mass and age do not present the same unique values of their observed parameters. Instead they follow a distribution. We address the study of such distributions, parameterised in terms of their confidence limits, in evolutionary synthesis models. These confidence limi

Joshua N. Winn, Jacqueline N. Hewitt, Paul L. Schechter, Alan Dressler

We report the discovery of a new double-image quasar that was found during a search for gravitational lenses in the southern sky. Radio source PMN J1838-3427 is composed of two flat-spectrum components with separation 1&#34;, flux density ratio 14:1 and matching spectral indices, in VLA and VLBA images. Ground-based BRI images show the optical counterpart (t

Akikazu Hashimoto, Shinji Hirano, N. Itzhaki

Recently it was suggested that a graviton in $AdS_5 \times S^5$ with a large momentum along the sphere can blow up into a spherical D-brane in $S^5$. In this paper we show that the same graviton can also blow up into a spherical D-brane in $AdS_5$ with exactly the same quantum numbers (angular momentum and energy). These branes are BPS, preserving 16 of the

Kristen Menou, Rosalba Perna, John Raymond

Rather than accreting via a disk, some White Dwarfs (WDs) in quiescent Dwarf Novae (DN) could accrete via an Advection-Dominated Accretion Flow (ADAF) possibly responsible for the X-ray Bremsstrahlung emission observed. Such a hot accretion flow is also expected to produce characteristic thermal line emission. Using SS Cyg as a specific example, we show that

Sultana N. Nahar, Anil K. Pradhan, Hong Lin Zhang

Photoionization and recombination cross sections and rate coefficients are calculated for Li-like Fe XXIV and He-like Fe XXV using the Breit-Pauli R-matrix (BPRM) method. A complete set of total and level-specific parameters is obtained to enable X-ray photoionization and spectral modeling. The ab initio calculations for the unified (e + ion) recombination r

J. A. Nieto, C. M. Yee

Using a special ansatz for the metric, by straightforward computation we prove that gravi-dilaton effective action in higher dimensions is reduced to the p-brane action. The dual symmetry of the generic type $%a\longleftrightarrow \frac 1a$ is an important symmetry of the reduced action.

Shung-ichi Ando, Fred Myhrer, Kuniharu Kubodera

Applying heavy-baryon chiral perturbation theory to ordinary muon capture (OMC) on a proton, we calculate the capture rate and neutron helicity asymmetry up to next-to-next-to-leading order. For the singlet hyperfine state, we obtain the capture rate Gamma_0 = 695 sec^{-1} while, for the triplet hyperfine state, we obtain the capture rate Gamma_1 = 11.9 sec^

Nathan Seiberg

Using the construction of D-branes with nonzero $B$ field in the matrix model we give a physical interpretation of the known background independence in gauge theories on a noncommutative space. The background independent variables are identified as the degrees of freedom of the underlying matrix model. This clarifies and extends some recent results about the

Mircea Mustata

We prove that if X is a locally complete intersection variety, then X has all the jet schemes irreducible if and only if X has canonical singularities. After embedding X in a smooth variety Y, we use motivic integration to express the condition that X has irreducible jet schemes in terms of data coming from an embedded resolution of X in Y. We show that this

A. Kritsuk, T. Plewa, E. Mueller

We use hydrodynamic simulations with adaptive grid refinement to study the dependence of hot gas flows in X-ray luminous giant elliptical galaxies on the efficiency of heat supply to the gas. We consider a number of potential heating mechanisms including Type Ia supernovae and sporadic nuclear activity of a central supermassive black hole. As a starting poin

Ichiro Oda

We study localization of bosonic bulk fields on a string-like defect with codimension 2 in a general space-time dimension in detail. We show that in cases of spin 0 scalar and spin 1 vector fields there are an infinite number of massless Kaluza-Klein (KK) states which are degenerate with respect to the radial quantum number, but only the massless zero mode s

Steven Manly, Eric Page

This paper describes a new class of experiments that use dispersion in optical fibers to convert the gravitational frequency shift of light into a measurable phase shift or time delay. Two conceptual models are explored. In the first model, long counter-propagating pulses are used in a vertical fiber optic Sagnac interferometer. The second model uses optical

Ron Donagi, Burt Ovrut, Tony Pantev, Dan Waldram

We describe a family of genus one fibered Calabi-Yau threefolds with fundamental group ${\mathbb Z}/2$. On each Calabi-Yau $Z$ in the family we exhibit a positive dimensional family of Mumford stable bundles whose symmetry group is the Standard Model group $SU(3)\times SU(2)\times U(1)$ and which have $c_{3} = 6$. We also show that for each bundle $V$ in our

Ron Donagi, Burt Ovrut, Tony Pantev, Dan Waldram

We give a proof of the existence of $G=SU(5)$, stable holomorphic vector bundles on elliptically fibered Calabi--Yau threefolds with fundamental group $\bbz_2$. The bundles we construct have Euler characteristic 3 and an anomaly that can be absorbed by M-theory five-branes. Such bundles provide the basis for constructing the standard model in heterotic M-the

J. I. Kim, R. B. B. Santos, P. Nussenzveig.

We show how the dynamics of collisions between cold atoms can be manipulated by a modification of spontaneous emission times. This is achieved by placing the atomic sample in a resonant optical cavity. Spontaneous emission is enhanced by a combination of multiparticle entanglement together with a higher density of modes of the modified vacuum field, in a sit

Ana Nunes, Jose P. Mimoso

In the present work we perform a phase-plane analysis of the complete dynamical system corresponding to a flat FRW cosmological models with a perfect fluid and a self-interacting scalar field and show that every positive and monotonous potential which is asymptotically exponential yields a scaling solution as a global attractor.

G. L. Fogli, E. Lisi, D. Montanino, A. Palazzo

In the context of solar neutrino oscillations among active states, we briefly discuss the current likelihood of Mikheyev-Smirnov-Wolfenstein (MSW) solutions to the solar neutrino problem, which appear to be currently favored at large mixing, where small Earth regeneration effects might still be observable in Super-Kamiokande (SK) and in the Sudbury Neutrino

E. Kh. Akhmedov, G. C. Branco, F. R. Joaquim, J. I. Silva-Marcos

In the framework of a minimal extension of the SM, where the only additional fields are three right-handed neutrinos, we suggest that the charged lepton, the Dirac neutrino and the right-handed Majorana neutrino mass matrices are all, to leading approximation, proportional to the democratic matrix. With the further assumption that the breaking of this extend

A. Piróth

The electroweak phase transition provides the most attractive framework to account for the baryon asymmetry of the universe. Comparing results of perturbative and nonperturbative studies is not straightforward, however, due to the different coupling constant definitions. The perturbative one stems from the $\bar{\mathrm{MS}}$ subtraction scheme, while the no

A. Celotti, G. Ghisellini, M. Chiaberge

X-ray emission from large scale extragalactic jets is likely to be due to inverse Compton scattering of relativistic particles off seed photons of both the cosmic microwave background field and the blazar nucleus. The first process dominates the observed high energy emission of large scale jets if the plasma is moving at highly relativistic speeds and if the

M. Kollar, D. Vollhardt

We study the Hubbard model with bond-charge interaction (`correlated hopping&#39;) in terms of the Gutzwiller wave function. We show how to express the Gutzwiller expectation value of the bond-charge interaction in terms of the correlated momentum-space occupation. This relation is valid in all spatial dimensions. We find that in infinite dimensions, where t

S. Mendoza, M. S. Longair

The model first introduced by Raga & Canto (1996) in which astrophysical jets are deflected on passing through an isothermal high density region is generalised by taking into account gravitational effects on the motion of the jet as it crosses the high density cloud. The problem is also generalised for relativistic jets in which gravitational effects induced

E. Gómez González, F. J. Plaza Martín

This paper generalizes for non-abelian theta functions a number of formulae valid for theta functions of Jacobian varieties. The addition formula, the relation with the Szego kernel and with the multicomponent KP hierarchy and the behavior under cyclic coverings are given.

A. V. Belitsky, A. Freund, D. Müller

We present a calculation of the two-loop evolution kernels of the twist-two transversally polarized quark and linearly polarized gluon skewed parton distributions in the minimal subtraction scheme and discuss a solution of the evolution equations suitable for numerical implementations.

Alejandro Cabo, Marcos Rigol

A recently proposed modified perturbative expansion for QCD incorporating gluon condensation is employed to evaluate the quark and gluon self-energy corrections in the first approximations. The results predict mass values of 1/3 of the nucleon mass for the light quarks u, d, and s and a monotonously growing variation with the current mass. The only phenomeno

Maryam Modjaz, Weidong Li, Alexei V. Filippenko, Jennifer Y. King

We present spectroscopic and extensive photometric observations of supernova (SN) 1998de in the S0 galaxy NGC 252, discovered during the course of the Lick Observatory Supernova Search. These data, which span a time period of 8 days before to 76 days after $B$-band maximum, unambigously establish SN 1998de as a peculiar and subluminous SN Ia with strong simi

Joop Schaye, Michael Rauch, Wallace L. W. Sargent, Tae-Sun Kim

The abundances of metals in the intergalactic medium (IGM) can be used to constrain the amount of star formation at high redshift and the spectral shape of the ionizing background radiation. For both purposes it is essential to measure the abundances in regions of low density, away from local sources of metals and ionizing photons. Here we report the first d