August 2001 arXiv papers — page 5

Joachim Krug

The coarsening of an array of vortex ripples prepared in an unstable state is discussed within the framework of a simple mass transfer model first introduced by K.H. Andersen et al. [Phys. Rev. E 63, 066308 (2001)]. Two scenarios for the selection of the final pattern are identified. When the initial state is homogeneous with uniform random perturbations, a

Daw-Wei Wang, S. Das Sarma

We develop a generic theory for the resonant inelastic light (Raman) scattering by a conduction band quantum plasma taking into account the presence of the filled valence band in doped semiconductor nanostructures within a generalized resonant random phase approximation (RPA). Our generalized RPA theory explicitly incorporates the two-step resonance process

Dietrich Stauffer, Jan P. Radomski

A simple evolutionary model for biological ageing is modified such that it requires a minimum population for survival, like in human society. This social effect leads to a transition between extinction and survival of the species.

Markus Aichhorn, Peter Horsch, Wolfgang von der Linden, Mario Cuoco

The temperature dependence of the integrated optical conductivity I(T) reflects the changes of the kinetic energy as spin and charge correlations develop. It provides a unique way to explore experimentally the kinetic properties of strongly correlated systems. We calculated I(T) in the frame of a t-J-V model at quarter-filling for ladder systems, like NaV_2O

Lorenz Bartosch, Peter Kopietz

We consider the effect of Coulomb interactions on the average density of states (DOS) of disordered low-dimensional metals for temperatures T and frequencies omega smaller than the inverse elastic life-time. Using the fact that long-range Coulomb interactions in two dimensions (2d) generate ln^2-singularities in the DOS nu (omega) but only ln-singularities i

S. M. M. Virtanen, T. P. Simula, M. M. Salomaa

We compute structures of vortex configurations in a harmonically trapped Bose-Einstein condensed atom gas within three different gapless self-consistent mean-field theories. Outside the vortex core region, the density profiles for the condensate and the thermal gas are found to differ only by a few percent between the Hartree-Fock-Bogoliubov-Popov theory and

Sune Jespersen, Hans C. Fogedby

We study the motion of a massive particle in a quenched random environment at zero temperature. The distribution of particle positions is investigated numerically and special focus is placed on the mean stopping distance and its fluctuations. We apply a scaling analysis in order to obtain analytical information about the distribution function. The model serv

Lidunka Vocadlo, Dario Alfe`

The melting curve of aluminium has been determined from 0 to ~150 GPa using first principles calculations of the free energies of both the solid and liquid. The calculations are based on density functional theory within the generalised gradient approximation using ultrasoft Vanderbilt pseudopotentials. The free energy of the harmonic solid has been calculate

Ram C. Singh, Jokhan Ram, Yashwant Singh

We have calculated the pair correlation functions of a fluid interacting via the Gay-Berne(n-6) pair potentials using the \PY integral equation theory and have shown how these correlations depend on the value of n which measures the sharpness of the repulsive core of the pair potential. These results have been used in the density-functional theory to locate

R. Nast, S. I. Schlachter, S. Zimmer, H. Reiner

Monofilamentary MgB2-wires with a 2- or 3-component sheath containing mechanical reinforcing stainless steel (SS) were prepared and characterized. In direct contact to the superconductor Nb, Ta or Fe was used. For a selection of samples with a Fe and Fe/SS sheath, we investigated the transport critical current behaviour in magnetic fields changing systematic

O. Morsch, J. H. Müller, M. Cristiani, D. Ciampini

We have loaded Bose-Einstein condensates into one-dimensional, off-resonant optical lattices and accelerated them by chirping the frequency difference between the two lattice beams. For small values of the lattice well-depth, Bloch oscillations were observed. Reducing the potential depth further, Landau-Zener tunneling out of the lowest lattice band, leading

A. V. Kornilov, V. M. Pudalov, Y. Kitaoka, K. Ishida

We report unexpected features of the transport in the dielectric spin density wave (SDW) phase of the quasi one-dimensional compound (TMTSF)_2PF_6: the resistance exhibits a maximum and a subsequent strong drop as temperature decreases below approximately 2K. The maximum in R(T) is not caused by depinning or Joule heating of the SDW. The characteristic tempe

Yashwant Singh, Jokhan Ram

Using the density functional formalism we derive expression for the distortion free energy for systems with continuous broken symmetry and use it to derive expression for the elastic constants of smectic phases in which director is tilted with respect to the smectic layer normal. As in the previous papers of the series (Phys. Rev. A {\bf 45}, 974 (1992), E {

Ashok Razdan

In this paper we study BSE Index financial time series for fractal and multifractal behaviour. We show that Bombay stock Exchange (BSE)Index time series is mono-fractal and can be represented by a fractional Brownian motion.

C. W. Gardiner, A. S. Bradley

We show that a correct formulation of the cold collision frequency shift for two photon spectroscopy of Bose-condensed and cold non-Bose-condensed hydrogen is consistent with experimental data. Our treatment includes transport and inhomogeneity into the theory of a non-condensed gas, which causes substantial changes in the cold collision frequency shift for

A. Kiraz, S. Falth, C. Becher, B. Gayral

We report photon correlation measurements that allow us to observe unique signatures of biexcitons in a single self-assembled InAs quantum dot. Photon correlation measurements of biexciton emission exhibit both bunching and antibunching under continuous-wave excitation while only antibunching is observed under pulsed excitation. Cross-correlation between bie

Mogens H. Jensen, Anders Levermann, Joachim Mathiesen, Benny Davidovitch

We study the nature of the phase transition in the multifractal formalism of the harmonic measure of Diffusion Limited Aggregates (DLA). Contrary to previous work that relied on random walk simulations or ad-hoc models to estimate the low probability events of deep fjord penetration, we employ the method of iterated conformal maps to obtain an accurate compu

M. J. Barber, J. W. Clark, C. H. Anderson

We continue to explore the hypothesis that neuronal populations represent and process analog variables in terms of probability density functions (PDFs). A neural assembly encoding the joint probability density over relevant analog variables can in principle answer any meaningful question about these variables by implementing the Bayesian rules of inference.

L. G. Titarchuk, C. F. Bradshaw, K. S. Wood

We present a method for determining the B-field around neutron stars based on observed kHz and viscous QPO frequencies used in combination with the best-fit optical depth and temperature of a Comptonization model. In the framework of the transition layer QPO model, we analyze magnetoacoustic wave formation in the layer between a neutron star surface and the

V. R. Chitnis, B. S. Acharya, P. N. Bhat, K. S. Gothe

Pachmarhi Array of Čerenkov Telescopes (PACT) has been designed to search for celestial TeV $γ-$rays using the wavefront sampling technique. PACT, located at Pachmarhi, (latitude 22$^\circ$ 28$^\prime$ N, longitude 76$^\circ$ 26$^\prime$ E, altitude 1075 m) consists of 25 telescopes deployed over an area of 80 m $\times$ 100m. Each telescopes consists of 7 p

Mahmoud Aburihan, Jason D. Fiege, Richard N. Henriksen, Thibaut Lery

The formation and collapse of a protostar involves the simultaneous infall and outflow of material in the presence of magnetic fields, self-gravity, and rotation. We use self-similar techniques to self-consistently model the anisotropic collapse and outflow by a set of angle-separated self-similar equations. The outflow is quite strong in our model, with the

Paul B. Eskridge, Andrea E. Schweitzer

We have studied the stellar population and internal structure of the core of the Ursa Minor dwarf spheroidal galaxy, using a sample of stars selected to be members based on their proper motions. In agreement with previous studies, we find Ursa Minor to be dominated by an old, metal-poor stellar population. A small number of stars with high membership probabi

Adam J. Burgasser, J. Davy Kirkpatrick, Michael E. Brown, I. Neill Reid

We present near-infrared spectra for a sample of T dwarfs, including eleven new discoveries made using the Two Micron All Sky Survey. These objects are distinguished from warmer (L-type) brown dwarfs by the presence of methane absorption bands in the 1--2.5 $\micron$ spectral region. A first attempt at a near-infrared classification scheme for T dwarfs is ma

Omer Blaes, Ivan Hubeny, Eric Agol, Julian H. Krolik

We fit general relativistic, geometrically thin accretion disk models with non-LTE atmospheres to near simultaneous multiwavelength data of 3C~273, extending from the optical to the far ultraviolet. Our model fits show no flux discontinuity associated with a hydrogen Lyman edge, but they do exhibit a spectral break which qualitatively resembles that seen in

Sabrina De Grandi, Silvano Molendi

We review observations on the chemical enrichment of the intracluster medium (ICM) performed using BeppoSAX MECS data. The picture emerging is that non-cooling flow clusters have flat metallicity profiles, whereas a strong enhancement in the abundance is found in the central regions of the cooling flow clusters. All the non-cooling flow clusters present evid

M. Boettcher, R. Schlickeiser, A. Marra

It is generally accepted that gamma-ray bursts (GRBs) are initiated by a relativistic pair fireball, converting its internal energy into kinetic energy of a relativistically moving plasmoid and subsequently into radiation. Here, we investigate the early stages of this evolution, after the pair fireball has become optically thin to gamma-gamma pair production

S. Campana, A. Moretti, D. Lazzati, G. Tagliaferri

The origin of the X-ray background, in particular at hard (2-10 keV) energies, has been a debated issue for more than 30 years. The Chandra deep fields provide the deepest look at the X-ray sky and are the best dataset to study the X-ray background. We searched the Chandra Deep Field South for X-ray sources with the aid of a dedicated wavelet-based algorithm

R. A. Allsman, T. S. Axelrod

The MACHO Project generated two-color photometric lightcurves for 73 million stars in the LMC, SMC, and the galactic bulge during its 8 years of observing. This photometry, along with all images and a catalog of LMC variable stars, is now available for viewing or download from the MACHO Project websites, http://wwwmacho.anu.edu.au/ or http://wwwmacho.mcmaste

Stephane Paulin-Henriksson

We report the discovery of a short-duration microlensing candidate in the Northern field of the POINT-AGAPE pixel lensing survey towards M31. The full-width at half-maximum timescale is very short (tfwhm = 1.8 days) and the source star has almost certainly been identified on HST images, allowing to infer an Einstein crossing time : te=10.4 days and a magnifi

Ignas Snellen, Philip Best

Deep and high resolution radio observations of the Hubble Deep Field and flanking fields have shown the presence of two distant edge-darkened FR I radio galaxies, allowing for the first time an estimate of their high redshift space density. If it is assumed that the space density of FR I radio galaxies at z>1 is similar to that found in the local universe, t

Peter Boschan

We measured the two dimensional galaxy--galaxy correlation function from the Muenster Red Sky Survey (Ungruhe 1999). This survey has a slightly larger surface as the APM survey and complete up to r_F<18.3 mag (z_{med} \sim 0.14). The large dynamical range of the survey made it possible to examine sub-catalogues with different limiting magnitudes. The positiv

B. Deufel, C. P. Dullemond, H. C. Spruit

We consider the interaction of a slowly rotating unmagnetized neutron star with a hot (ion supported, ADAF) accretion flow. The virialized protons of the ADAF penetrate into the neutron star atmosphere, heating a surface layer. Detailed calculations are presented of the equilibrium between heating by the protons, electron thermal conduction, bremsstrahlung a

G. Parmentier, G. Gilmore

We discuss the existence of a mass-metallicity relation among galactic halo globular clusters. The lack of any luminosity-metallicity correlation in globular cluster systems has been used as an argument against self-enrichment models of cluster formation. We show that such a relation is statistically present among the galactic Old Halo globulars. This observ

D. A. Frail, F. Bertoldi, G. H. Moriarty-Schieven, E. Berger

We present millimeter and submillimeter wavelength observations and near-infrared K-band imaging toward the bright gamma-ray burst GRB 010222. Over seven epochs the flux density of the source was constant with an average flux density 3.74+/-0.53 mJy at 350 GHz and 1.05+/-0.22 mJy at 250 GHz, giving a spectral index alpha=3.78+/-0.25. We rule out the possibil

S. K. Leggett, D. A. Golimowski, X. Fan, T. R. Geballe

We present ZJHKL&#39;M&#39; photometry of a sample of 58 late-M, L, and T dwarfs, most of which are identified from the Sloan Digital Sky Survey and the Two Micron All-Sky Survey. Near-infrared spectra and spectral classifications for most of this sample are presented in a companion paper by Geballe et al. We derive the luminosities of 18 dwarfs in the sampl

M. Nagashima, T. Totani, N. Gouda, Y. Yoshii

Number counts of galaxies are re-analyzed using a semi-analytic model (SAM) of galaxy formation based on the hierarchical clustering scenario. We have determined the astrophysical parameters in the SAM that reproduce observations of nearby galaxies, and used them to predict the number counts and redshifts of faint galaxies for three cosmological models for (

Abraham Loeb

I consider novel ways by which Gamma-Ray Bursts (GRBs) and quasars can be used to probe the universe. Clues about how and when was the intergalactic medium ionized can be read off the UV emission spectrum of GRB explosions from the first generation of stars. The existence of intergalactic and galactic stars can be inferred from their gravitational microlensi

Carl H. Gibson

Chaotic, eddy-like motions dominated by inertial-vortex forces begin immediately at Planck scales in a hot big-bang cosmological model. This quantum-gravitational-dynamics epoch produced not only the first space-time-energy of the universe but the first large Reynolds number turbulence and turbulent mixing with Kolmogorov and Batchelor-Obukhov-Corrsin veloci

Rennan Barkana

In light of recent observations of spectra of the quasars SDSS 1030+0524 (Becker et al. 2001) and SDSS 1044-0125 (Djorgovski et al. 2001), we study the observational signatures of different stages of the reionization epoch. During the initial, pre-overlap stage, the hydrogen throughout the universe is neutral except for isolated HII bubbles due to individual

Z. Toroczkai

The Horton-Strahler (HS) index $r=\max{(i,j)}+δ_{i,j}$ has been shown to be relevant to a number of physical (such at diffusion limited aggregation) geological (river networks), biological (pulmonary arteries, blood vessels, various species of trees) and computational (use of registers) applications. Here we revisit the enumeration problem of the HS index on

Eran A. Mukamel, Eugene I. Shakhnovich

We present a critique and extension of the mean-field approach to the mechanical pulling transition in bound polymer systems. Our model is motivated by the theoretically and experimentally important examples of adsorbed polymers and double-stranded DNA, and we focus on the case in which quenched disorder in the sequence of monomers is unimportant for the sta

Yu. V. Shtanov

We construct solutions in purely gravitational bulk with flat vacuum branes without fine tuning the constants of the theory. Our solutions incorporate one or two branes and have topology S^1 x R^4 without Z_2 symmetry. They are not invariant under the four-dimensional Lorentz group effectively acting on the brane, but the significance of this fact will becom

Steven S. Gubser, Arkady A. Tseytlin, Mikhail S. Volkov

We study extremal and non-extremal generalizations of the regular non-abelian monopole solution of hep-th/9707176, interpreted in hep-th/0007018 as 5-branes wrapped on a shrinking S^2. Naively, the low energy dynamics is pure N=1 supersymmetric Yang-Mills. However, our results suggest that the scale of confinement and chiral symmetry breaking in the Yang-Mil

Masaki Oshikawa, Ian Affleck

A systematic field-theory approach to Electron Spin Resonance (ESR) in the $S=1/2$ quantum antiferromagnetic chain at low temperature $T$ (compared to the exchange coupling $J$) is developed. In particular, effects of a transverse staggered field $h$ and an exchange anisotropy (including a dipolar interaction) $δ$ on the ESR lineshape are discussed. In the l

M. Bertola, B. Eynard, J. Harnad

The statistical distribution of eigenvalues of pairs of coupled random matrices can be expressed in terms of integral kernels having a generalized Christoffel--Darboux form constructed from sequences of biorthogonal polynomials. For measures involving exponentials of a pair of polynomials V_1, V_2 in two different variables, these kernels may be expressed in

Jose A. Riera

We study a two-dimensional t-J model close to the Ising limit in which charge inhomogeneity is stabilized by an on-site potential e_s, by using diagonalization in a restricted Hilbert space and finite temperature Quantum Monte Carlo. Both site and bond centered stripes are considered and their similitudes and differences are analyzed. The amplitude of charge

Kari Enqvist, Hannu Kurki-Suonio, Jussi Valiviita

We consider pure isocurvature cold dark matter models in the case of open and closed universe. We allow for a large spectral tilt and scan the 6-dimensional parameter space for the best fit to the COBE, Boomerang, and Maxima-1 data. Taking into account constraints from large-scale structure and big bang nucleosynthesis, we find a best fit with $χ^2 = 121$, w

Bert Schroer

The limitations of the approach based on using fields restricted to the lightfront (Lightfront Quantization or p$\to \infty $ Frame Approach) which drive quantum fields towards canonical and ultimately free fields are well known. Here we propose a new concept which does not suffer from this limitation. It is based on a procedure which cannot be directly form

Marshall Bern, David Eppstein, Jeff Erickson

We define and examine flip operations for quadrilateral and hexahedral meshes, similar to the flipping transformations previously used in triangular and tetrahedral mesh generation.

C. L. Kane, Ranjan Mukhopadhyay, T. C. Lubensky

We demonstrate the emergence of the quantum Hall (QH) hierarchy in a 2D model of coupled quantum wires in a perpendicular magnetic field. At commensurate values of the magnetic field, the system can develop instabilities to appropriate inter-wire electron hopping processes that drive the system into a variety of QH states. Some of the QH states are not inclu

Matthias R. Gaberdiel, Sakura Schafer-Nameki

A dual pair of supersymmetric string theories that involves an asymmetric orbifold and an orientifold of Type II is considered. The D-branes of the orbifold theory (that were recently determined by Gutperle) are all non-BPS and do not carry any conserved gauge charges. It is shown that they carry non-trivial K-theory charges, and that they can be understood

Pedro Bordalo, Sylvain Ribault, Christoph Schweigert

We consider the Born-Infeld action for symmetry-preserving, orientable D-branes in compact group manifolds. We find classical solutions that obey the flux quantization condition. They correspond to conformally invariant boundary conditions on the world sheet. We compute the spectrum of quadratic fluctuations and find agreement with the predictions of conform

Tod E. Strohmayer, Edward F. Brown

We present a detailed observational and theoretical study of a ~3 hr long X-ray burst (the ``super burst&#39;&#39;) observed by the Rossi X-ray Timing Explorer (RXTE) from the low mass X-ray binary (LMXB) 4U 1820-30. This is the longest X-ray burst ever observed from this source, and perhaps one of the longest ever observed in great detail from any source. W

Jitse Niesen

The Alekseev-Gr{ö}bner lemma is combined with the theory of modified equations to obtain an \emph{a priori} estimate for the global error of numerical integrators. This estimate is correct up to a remainder term of order $h^{2p}$, where $h$ denotes the step size and $p$ the order of the method. It is applied to a class of nonautonomous linear oscillatory equ

F. A. Aharonian, A. N. Timokhin, A. V. Plyasheshnikov

The spectra of very high energy gamma-radiation from distant extragalactic objects suffer significant deformations during the passage of primary gamma-rays through the intergalactic medium. The recently reported fluxes of diffuse infrared background radiation indicate that we detect, most probably, heavily absorbed TeV radiation from Mkn 421 and Mkn 501. Thi

G. Clementini, L. Federici, C. E. Corsi, C. Cacciari

The purpose of this paper is to show that RR Lyrae variables exist and can be detected in M31 globular clusters. We report on the first tentative identification of RR Lyrae candidates in four globular clusters of the Andromeda galaxy, i.e. G11, G33, G64 and G322. Based on HST-WFPC2 archive observations in the F555W and F814W filters spanning a total interval

R. J. McLure, J. S. Dunlop

New black-hole mass estimates are presented for a sample of 72 AGN covering three decades in optical luminosity. Using a sub-sample of Seyfert galaxies, which have black-hole mass estimates from both reverberation mapping and stellar velocity dispersions, we investigate the geometry of the AGN broad-line region (BLR). It is demonstrated that a model in which

Amir H. Fatollahi

We consider the problem of the interaction between D0-brane bound state and 1-form RR photons by the world-line theory. Based on the fact that in the world-line theory the RR gauge fields depend on the matrix coordinates of D0-branes, the gauge fields also appear as matrices in the formulation. At the classical level, we derive the Lorentz-like equations of

M. E. Bracco, M. Chiapparini, A. Lozea, F. S. Navarra

The DDrho form factor is evaluated in a QCD sum rule calculation for both D and rho off-shell mesons. We study the double Borel sum rule for the three point function of two pseudoscalar and one vector meson currents. We find that the momentum dependence of the form factors is very different if the D or the rho meson is off-shell, but they lead to the same co

A. Crisanti, L. Leuzzi, G. Parisi

In this paper we analyze the structure of the UNSAT-phase of the overconstrained 3-SAT model by studying the low temperature phase of the associated disordered spin model. We derive the $\infty$ Replica Symmetry Broken equations for a general class of disordered spin models which includes the Sherrington - Kirkpatrick model, the Ising $p$-spin model as well

Ishwaree P. Neupane

We argue that the van Dam-Veltman-Zakharov discontinuity arising in the $M^2 \to 0$ limit of the massive graviton through an explicit Pauli-Fierz mass term could be absent in anti de Sitter space. This is possible if the graviton can acquire mass spontaneously from the higher curvature terms or/and the massless limit $M^2\to 0$ is attained faster than the co

X. X. Chen, G. Tian

In our previous paper math.DG/0010008, we develop some new techniques in attacking the convergence problems for the Kähler Ricci flow. The one of main ideas is to find a set of new functionals on curvature tensors such that the Ricci flow is the gradient like flow of these functionals. We successfully find such functionals in case of Kaehler manifolds. On Kä

C. Wetterich

The scalar ``cosmon&#39;&#39; field mediating quintessence influences the dynamics of extended objects in the universe. We discuss cosmon lumps -- spherically symmetric solutions for the scalar field coupled to gravity. The two integration constants can be associated to the mass and the rotational velocity in a halo-like region with constant rotation curve.

Takashi Shirahata, Tota Nakamura

An axial next-nearest-neighbor Ising (ANNNI) model is studied by using the non-equilibrium relaxation method. We find that the incommensurate stripe phase between the ordered phase and the paramagnetic phase is negligibly narrow or may vanish in the thermodynamic limit. The phase transition is the second-order transition if approached from the ordered phase,

XuBo Zou, K. Pahlke, W. Mathis

We present a scheme to generate an arbitrary two-dimensional quantum state of motion of a trapped ion. This proposal is based on a sequence of laser pulses, which are tuned appropriately to control transitions on the sidebands of two modes of vibration. Not more than $(M+1)(N+1)$ laser pulses are needed to generate a pure state with upper phonon number $M$ a

Radim Filip

A generic model of measurement device which is able to directly measure commonly used quantum-state characteristics such as fidelity, overlap, purity and Hilbert-Schmidt distance for two general uncorrelated mixed states is proposed. In addition, for two correlated mixed states, the measurement realizes an entanglement witness for Werner&#39;s separability c

Robert Raussendorf, Daniel E. Browne, Hans J. Briegel

A one-way quantum computer works by only performing a sequence of one-qubit measurements on a particular entangled multi-qubit state, the cluster state. No non-local operations are required in the process of computation. Any quantum logic network can be simulated on the one-way quantum computer. On the other hand, the network model of quantum computation can

Radim Filip

New feasible cavity QED experiment is proposed to analyse reversible quantum decoherence in consequence of quantum complementarity and entanglement. Utilizing the phase selective manipulations with enviroment, it is demonstrated how the complementarity particularly induces a preservation of visibility, whereas quantum decoherence is more progressive due to p

M. O. Oktel, L. S. Levitov

Theory for the Rabi and internal Josephson effects in an interacting Bose gas in the cold collision regime is presented. By using microscopic transport equation for the density matrix the problem is mapped onto a problem of precession of two coupled classical spins. In the absence of an external excitation field our results agree with the theory for the dens

Nigel Baker, Peter Brooks, Richard McClatchey, Zsolt Kovacs

Optimising use of the Web (WWW) for LHC data analysis is a complex problem and illustrates the challenges arising from the integration of and computation across massive amounts of information distributed worldwide. Finding the right piece of information can, at times, be extremely time-consuming, if not impossible. So-called Grids have been proposed to facil

Harald W. Griesshammer

Progress in the Effective Field Theory of two and three nucleon systems is sketched, concentrating mainly on the low energy version in which pions are integrated out as explicit degrees of freedom. Examples given are: the extraction of nucleon polarisabilities from deuteron Compton scattering at very low energies; the energy dependence of the nucleon polaris

Renat Kh. Gainutdinov, Aigul A. Mutygullina

We discuss the problem of renormalization of dynamical equations which arises in an effective field theory description of nuclear forces. By using a toy model of the separable NN potential leading to logarithmic singularities in the Born series, we show that renormalization gives rise to nucleon dynamics which is governed by a generalized dynamical equation

S. Karataglidis, D. G. Madland

Detailed comparisons are made between results of calculations for intermediate energy nucleon--208Pb scattering using optical potentials obtained from Dirac phenomenology and a microscopic Schrodinger model. The two approaches yield quite similar results for all of the observables with each projectile, including spin observables, suggesting the two models ar

F. Plenge, P. Rodin, E. Schöll, K. Krischer

Spatio-temporal bifurcations and complex dynamics in globally coupled intrinsically bistable electrochemical systems with an S-shaped current-voltage characteristic under galvanostatic control are studied theoretically on a one-dimensional domain. The results are compared with the dynamics and the bifurcation scenarios occurring in a closely related model wh

Ph. Jacquod, P. G. Silvestrov, C. W. J. Beenakker

The overlap of two wave functions evolving in time with slightly different Hamiltonians decays exponentially, for perturbation strengths greater than the level spacing. We present numerical evidence for a dynamical system that the decay rate is given by the smallest of the Lyapunov exponent of the classical chaotic dynamics and the level broadening that foll

Andrei Caldararu

In general, if M is a moduli space of stable sheaves on X, there is a unique alpha in the Brauer group of M such that a pi_M^* alpha^{-1}-twisted universal sheaf exists on X times M. In this paper we study the situation when X and M are K3 surfaces, and we identify alpha in terms of Mukai&#39;s map between the cohomology of X and of M (defined by means of a

Lei Yang

We give the trace formulas of weight $k$ for cocompact, torsion-free discrete subgroups of $SU(2, 1)$ and prove the analogue of the Riemann hypothesis on compact complex surfaces $M$ with $c_1^2(M)=3 c_2(M)$, where $c_i(M)$ is the $i$-th Chern class of $M$, $c_2(M)$ is a multiple of three and $c_2(M)>0$.

Oleg Pikhurko

We investigate size Ramsey numbers involving bipartite graphs. It is proved that, if each forbidden graph is fixed or grows with n (in a certain uniform manner), then the extremal function has a linear asymptotics. The corresponding slope can be obtained as the minimum of a certain mixed integer program. Applying the Farkas Lemma, we solve the MIP for comple

Eyal Markman, Eugene Z. Xia

For a compact Riemann surface $X$ of genus $g > 1$, $\Hom(π_1(X), PU(p,q))/PU(p,q)$ is the moduli space of flat $PU(p,q)$-connections on $X$. There are two invariants, the Chern class $c$ and the Toledo invariant $τ$ associated with each element in the moduli. The Toledo invariant is bounded in the range $-2min(p,q)(g-1) \le τ\le 2min(p,q)(g-1)$. This paper

Greg Kuperberg

In a previous article [math.CO/9712207], we derived the alternating-sign matrix (ASM) theorem from the Izergin-Korepin determinant for a partition function for square ice with domain wall boundary. Here we show that the same argument enumerates three other symmetry classes of alternating-sign matrices: VSASMs (vertically symmetric ASMs), even HTSASMs (half-t

Fernando Falceto, Krzysztof Gawedzki

We study a boundary version of the gauged WZW model with a Poisson-Lie group G as the target. The Poisson-Lie structure of G is used to define the Wess-Zumino term of the action on surfaces with boundary. We clarify the relation of the model to the topological Poisson sigma model with the dual Poisson-Lie group G^* as the target and show that the phase space

Ulrich Theis, Peter van Nieuwenhuizen

We construct and check by explicit Feynman diagram calculations the BRST Ward identities for N=2 rigid super Yang-Mills theory and N=2 extended supergravity in four-dimensional Euclidean space without auxiliary fields. We use the Batalin-Vilkovisky formalism. In the supergravity case we need one new contractible pair of complex spinor fields to obtain the us

S. J. Gates, M. T. Grisaru, M. Rocek, W. Siegel

The 1983 book, free at last, with corrections and bookmarks. From the original troff, but now with CM (TeX) fonts.

A. A. Bytsenko, M. C. Falleiros, A. E. Goncalves, Z. G. Kuznetsova

We give some remarks on twisted determinant line bundles and Chern-Simons topological invariants associated with real hyperbolic manifolds. Index of a twisted Dirac operator is derived. We discuss briefly application of obtained results in topological quantum field theory.

M. A. De Andrade, M. A. Santos, I. V. Vancea

The basic arguments underlying the symplectic projector method are presented. By this method, local free coordinates on the constrait surface can be obtained for a broader class of constrained systems. Some interesting examples are analyzed.

Roberto Casalbuoni

We describe low energy physics in the CFL and LOFF phases by means of effective lagrangians. In the CFL case we present also how to derive expressions for the parameters appearing in the lagrangian via weak coupling calculations taking advantage of the dimensional reduction of fermion physics around the Fermi surface. The Goldstone boson of the LOFF phase tu

Shoko Hayakawa, Takayuki Hirayama, Ryuichiro Kitano

We present a simple brane-world model in five dimensions. In this model we do not need any fine-tuning between the five dimensional cosmological constant and the brane tension to obtain four dimensional flat Minkowski space. The space-time of our solution has no naked singularities. Further the compactification scale of the fifth direction is automatically d

Bert Schroer

Recent developments in local quantum physics have led to revolutionary conceptual changes in the thinking about a more intrinsic formulation and in particular about unexpected aspects of localized degrees of freedom. This paradigmatic change is most spectacular in a new rigorous form of ``holography&#39;&#39; and ``transplantation&#39;&#39; as generic proper

Minoru Hirayama, Jun Yamshita

This paper has been withdrawn by the authors.

Janusz Rosiek

We discuss corrections to $ΔM_{B_d}$, $ΔM_{B_s}$ and to the CP violation parameter $ε$ in two examples of (generalized) minimal flavour violation models: 2HDM and MSSM in the large $\tanβ$ limit. We show that for $H^+$ not too heavy, $ΔM_{B_s}$ in the MSSM with heavy sparticles can be substantially smaller than in the SM due the charged Higgs box contributio

Rouzbeh Allahverdi, Kari Enqvist, Anupam Mazumdar, Abdel Pérez-Lorenzana

We describe a simple and predictive scenario for baryogenesis in theories with large extra dimensions which resembles Affleck-Dine baryogenesis. The Affleck-Dine field is a complex scalar field carrying a $U(1)_χ$ charge which is dynamically broken after the end of inflation. This generates an excess of $χ$ over $\bar χ$, which then decays into Standard Mode

V. G. Krivokhijine, A. V. Kotikov

We reanalyze deep inelastic scattering data of BCDMS Collaboration by including proper cuts of ranges with large systematic errors. We perform also the fits of high statistic deep inelastic scattering data of BCDMS, SLAC, NM and BFP Collaborations taking the data separately and in combined way and find good agreement between these analyses. We extract the va

Einan Gardi

Perturbative and non-perturbative aspects of differential cross-sections close to a kinematic threshold are studied applying ``dressed gluon exponentiation&#39;&#39; (DGE). The factorization property of soft and collinear gluon radiation is demonstrated using the light-cone axial gauge: it is shown that the singular part of the squared matrix element for the

Michael Melles

Recent investigations of electroweak radiative corrections have revealed the importance of higher order contributions in high energy processes, where the size of typical corrections can exceed those associated with QCD considerably. Beyond one loop, only universal (angular independent) corrections are known to all orders except for massless $e^+ e^- \longrig

M. Diehl, P. Kroll, C. Vogt

We investigate the possibility to constrain the pion distribution amplitude from the gamma* gamma* -> pi transition. For a surprisingly large range in the two photon virtualities we find that the transition form factor is essentially independent of the distribution amplitude. This in turn entails a parameter-free prediction of QCD. The gamma* gamma* -> eta,

Kazuyuki Fujii

First we make a brief review of coherent states and prove that the resolution of unity can be obtained by the 1-st Chern character of some bundle. Next we define a Grassmann manifold for a set of coherent states and construct the pull-back bundle making use of a projector from the parameter space to this Grassmann manifold. We study some geometric properties

M. Kirchbach, M. Moshinsky, Yu. F. Smirnov

The structure of the reported excitation spectra of the light unflavored baryons is described in terms of multi-spin valued Lorentz group representations of the so called Rarita-Schwinger (RS) type (K/2, K/2)* [(1/ 2,0)+ (0,1/2)] with K=1,3, and 5. We first motivate legitimacy of such pattern as fundamental fields as they emerge in the decomposition of tripl

A. Anastassov

We present the first measurement of the D*+ width using 9/fb of e+ e- data collected near the Upsilon(4S) resonance by the CLEO II.V detector. Our method uses advanced tracking techniques and a reconstruction method that takes advantage of the small vertical size of the CESR beam spot to measure the energy release distribution from the D*+ -> D0 pi+ decay. W

L. Baldini, L. Brocco, D. Casadei, G. Castellini

The Time of Flight (TOF) system of the AMS experiment provides the fast trigger to the detector and measures the crossing particle direction, velocity and charge. AMS was operated aboard of the shuttle Discovery on June 1998 (NASA STS-91 mission) and will be upgraded and installed on the International Space Station at the end of 2003, for 3 years of data tak

B. T. Fleming, J. Krane, G. P. Zeller, F. Canelli

The Young Physicists Panel (YPP) summarizes results from their Survey on the Future of High Energy Physics, which was conducted from July 2 to July 15, 2001. Over 1500 physicists from around the world, both young and tenured, responded to the survey. We first describe the origin, design, and advertisement of the survey, and then present the demographics of t