April 1997 arXiv papers — page 5

Ulf-G. Meißner, G. Müller, S. Steininger

We construct the generating functional of two flavor chiral perturbation theory including the effects of virtual photons in the one loop approximation. As an application, we calculate the electromagnetic corrections to the elastic $ππ$ scattering amplitude, in particular to its S--wave threshold parameters. Numerical estimates are given for the reaction $π^0

Patrick Irwin

Some aspects of the fields of charge two SU(3) monopoles with minimal symmetry breaking are discussed. A certain class of solutions look like SU(2) monopoles embedded in SU(3) with a transition region or ``cloud'' surrounding the monopoles. For large cloud size the relative moduli space metric splits as a direct product AH\times R^4 where AH is the A

Klaus Dolag, Matthias Bartelmann

We calculate the angular cross-correlation function between background QSOs and foreground galaxies induced by the weak lensing effect of large-scale structures. Results are given for arbitrary Friedmann-Lemaitre cosmologies. The non-linear growth of density perturbations is included. Compared to the linear growth, the non-linear growth increases the correla

N. B. Kopnin, G. E. Volovik

We demonstrate that superclean d-wave superconductors display a novel type of vortex dynamics: At low temperatures, both dissipative and transverse components of the flux-flow conductivity are found to approach universal values even in the limit of infinite relaxation time. A finite dissipation in the superclean limit is explained in terms of the Landau damp

Fabian Braun, Jan von Delft, D. C. Ralph, M. Tinkham

We study the magnetic-field-induced breakdown of superconductivity in nm-scale metal grains having a mean electron level spacing $d \simeq \tildeΔ$ (bulk gap). Using a generalized variational BCS approach that yields good qualitative agreement with measured spectra, we argue that Pauli paramagnetism dominates orbital diamagnetism, as in the case of thin film

Brian K. Davis

A system containing a pre-steady state standard (non-autocatalytic) reaction, with multiple paths, evolves toward a kinetic state with the minimum attainable activation free energy. Displacement of the path frequency distribution in this transition was shown to minimise the affinity linked to this change in activation free energy. In damping this scalar forc

G. Gyuk, E. Gates

We investigate the implications of a bulk rotational component of the halo velocity distribution for MACHO mass estimates. We find that for a rotating halo to yield a MACHO mass estimate significantly below that of the standard spherical case, its microlensing must be highly concentrated close to the Sun. We examine two classes of models fitting this criteri

O. Lipan, P. B. Wiegmann, A. Zabrodin

We show that the set of transfer matrices of an arbitrary fusion type for an integrable quantum model obey these bilinear functional relations, which are identified with an integrable dynamical system on a Grassmann manifold (higher Hirota equation). The bilinear relations were previously known for a particular class of transfer matrices corresponding to rec

J. Cleymans

Strangeness plays an important role in the study of quark matter since it indicates the rate at which new particles are being produced and therefore provides information about the degree of chemical equilibration reached in heavy ion collisions. It is shown that ratios provide an excellent method for determining the temperature and the chemical potential sin

H. W. Barz, J. P. Bondorf, J. J. Gaardhøje, H. Heiselberg

The influence of the nuclear Coulomb field on transverse spectra of $π^+$ and $π^-$ measured in $Pb+Pb$ reactions at 158 A GeV has been investigated. Pion trajectories are calculated in the field of an expanding fireball. The observed enhancement of the $π^-/π^+$ ratio at small momenta depends on the temperature and transverse expansion velocity of the sourc

J. Wurzer, H. M. Hofmann

The halo nuclei $^6$He and $^8$He are described in a consistent way in a microscopic multiconfiguration model, the refined resonating group method. The ground state properties have been calculated, and momentum distributions of fragments and neutrons have been determined in a simple reaction scenario, taking into account final-state interactions. The correla

I. B. Khriplovich, R. A. Sen'kov

The correction to the hydrogen Lamb shift due to the proton electric and magnetic polarizabilities is expressed analytically through their static values, which are known from experiment. The numerical value of the correction is $ - 71 \pm 11 \pm 7$ Hz.

Vania Mascioni, Lajos Molnar

The aim of this paper is to characterize those linear maps from a von Neumann factor $\A$ into itself which preserve the extreme points of the unit ball of $\A$. For example, we show that if $\A$ is infinite, then every such linear preserver can be written as a fixed unitary operator times either a unital *-homomorphism or a unital *-antihomomorphism.

M. N. Chernodub, M. I. Polikarpov, A. I. Veselov

The general properties of the abelian projection are reviewed. We derive the explicit expression for the abelian functional integral for U(1) abelian theory which corresponds to the abelian projection of the SU(2) gluodynamics. The numerical results for the temperature dependence of the monopole condensate are presented.

Matej Pavsic

The theory of the usual, constrained p-branes is embedded into a larger theory in which there is no constraints. In the latter theory the Fock-Schwinger proper time formalism is extended from point-particles to membranes of arbitrary dimension. For this purpose the tensor calculus in the infinite dimensional membrane space M is developed and an action which

M. J. Martins, P. B. Ramos

We consider the exact solution of a model of correlated electrons based on the superalgebra $Osp(2|2)$. The corresponding Bethe ansatz equations have an interesting form. We derive an expression for the ground state energy at half filling. We also present the eigenvalue of the transfer matrix commuting with the Hamiltonian.

Stephen Godfrey

We investigate the effects of extra neutral gauge bosons on the high $Q^2$ region of the $e^+p \to e^+ X$ cross section at $\sqrt{s}=300$ GeV. We found that the only models with electroweak strength coupling, typical of extended gauge theories, that give a better fit to the H1 and ZEUS high $Q^2$ data than the standard model, are ruled out by existing data f

Jan Bolz, Peter Kroll, Gerhard A. Schuler

Exclusive processes at large momentum transfer Q factor into perturbatively calculable short-distance parts and long-distance hadronic wave functions. Usually, only contributions from the leading Fock states have to be included to leading order in 1/Q. We show that for exclusive decays of P-wave quarkonia the contribution from the next-higher Fock state |Q Q

Andrzej J. Buras, Robert Fleischer

We review the highlights of quark mixing, particle-antiparticle mixing, CP violation and rare K- and B-decays in the Standard Model. The top quark discovery, the precise measurement of its mass, the improved knowledge of the couplings $V_{cb}$ and $V_{ub}$, and the calculations of NLO short distance QCD corrections improved considerably the predictions for v

P. Colangelo, G. Corcella

We study the sensitivity of an asymmetric B-factory to indirect CPT violating effects. We find that both dilepton signals and nonleptonic asymmetries can be used to bound the space of parameters describing possible CPT violation in the mixing matrix of the neutral B system.

S. Esposito, V. Fiorentino, G. Mangano, G. Miele

The resonant transition effects MSW and NSFP for three flavour Majorana neutrinos in a supernova are considered, where the transition magnetic moments are likely to play a relevant role in neutrino physics. In this scenario, the deformed thermal neutrino distributions are obtained for different choices of the electron-tau mixing angle. Detailed predictions f

Jiri Hosek

SU(2)xU(1) electroweak gauge model without Higgs sector is extended by a new vector field C interacting with leptons and quarks of both chiralities. This interaction is treated under a dynamical assumption in a self-consistent approximation. Fermion masses are calculated in terms of new Abelian hypercharges, and the intermediate boson masses are calculated i

B. Z. Kopeliovich, B. Povh, E. Predazzi

We argue that diffractive DIS, dominated by soft interactions, is probably the unique process which allows us to observe unitarity effects in DIS. Guided by a close analogy between the diffractive dissociation of a highly virtual photon and the elastic scattering of hadrons we propose a specific procedure to analyse the data in order to detect the onset of t

Colin Morningstar, Mike Peardon

Monte Carlo results for the low-lying glueball spectrum using an improved, anisotropic action are presented. Ten simulations at lattice spacings ranging from 0.2 to 0.4 fm and two different anisotropies have been performed in order demonstrate the advantages of using coarse, anisotropic lattices to calculate glueball masses. Our determinations of the tensor

Akihiro Ishibashi, Hideki Ishihara

We study a coupled system of gravitational waves and a domain wall which is the boundary of a vacuum bubble in de Sitter spacetime. To treat the system, we use the metric junction formalism of Israel. We show that the dynamical degree of the bubble wall is lost and the bubble wall can oscillate only while the gravitational waves go across it. It means that t

Johan Kustermans

In this paper, we construct a universal C*-algebraic quantum group out of an algebraic one. We show that this universal C*-algebraic quantum group has the same rich structure as its reduced companion. This universal C*-algebraic quantum group also satifies an upcoming definition of Masuda, Nakagami & Woronowicz except for the possible non-faithfulness of the

Jim Bryan

Furuta's ``10/8-th's'' theorem gives a bound on the magnitude of the signature of a smooth spin 4-manifold in terms of the second Betti number. We show that in the presence of a Z/2^p action, his bound can be strengthened. As applications, we give new genus bounds on classes with divisibility and we give a classification of involutions on rat

J. J. Vicente Alvarez, D. Dominguez, C. A. Balseiro

We study the dynamics of vortices in d-wave superconductors using a phenomenological time-dependent Ginzburg-Landau equation with mixing of s- and d-wave components. We present numerical simulations under an external driving current $J$ oriented with an angle $ϕ$ with respect to the $b$ crystal axis, calculating the vortex motion and induced electric fields

Alexander K. Hartmann

Ground states of 3d EA Ising spin glasses are calculated for sizes up to $14^3$ using a combination of genetic algorithms and cluster-exact approximation . The distribution $P(|q|)$ of overlaps is calculated. For increasing size the width of $P(|q|)$ converges to a nonzero value, indicating that many pure ground states exist for short range Ising spin glasse

P. Wojtaszczyk, J. B. Avalos, J. M. Rubi

The kinetics of the deposition of colloidal particles onto a solid surface is analytically studied. We take into account both the diffusion of particles from the bulk as well as the geometrical aspects of the layer of adsorbed particles. We derive the first kinetic equation for the coverage of the surface (a generalized Langmuir equation) whose predictions a

George Balster Martins, Markus Laukamp, Jose Riera, Elbio Dagotto

The local enhancement of antiferromagnetic correlations near vacancies observed in a variety of spin systems is analyzed in a single framework. Variational calculations suggest that the resonating-valence-bond character of the spin correlations at short distances is responsible for the enhancement. Numerical results for uniform spin chains, with and without

K. Ziegler, G. Jug

The question of the universality of the longitudinal peak conductivity at the integer quantum Hall transition is considered. For this purpose, a system of 2D Dirac fermions with random mass characterised by variance $g$ is proposed as a model which undergoes a quantum Hall transition. Whilst for some specific models the longitudinal peak conductivity $σ_{xx}

J. -Q. Liang, H. J. W. Mueller-Kirsten, J. M. S. Rana

The level splitting formulae much discussed in the study of spin tunneling in macroscopic ferromagnetic particles and previously derived only by complicated pseudoparticle methods for the ground state, are derived from those of eigenvalues of periodic equations and extended to excited states.

N. Kumar

The anisotropy of the scattering rates, 1/$τ_{tr} \propto T$ and 1/$τ_H \propto T^2$, implied effectively by the anomalous temperature dependence of the normal-state in-plane Hall angle, $\cot θ\propto T^2$, observed in the high-T$_c$ layered cuprates is reasoned out to be a natural consequence of the semiclassical Boltzmann transport equation with crossed e

A. C. Maggs

Experiments have been performed using microscopic beads to probe the small scale mechanics of actin solutions. We show that that there are a number of regimes possible as a function of the size of the probing particle. In certain cases we argue that the quasi-static response resembles a smectic crystal rather than an isotropic solid, implying an anomalous sc

Takuya Okabe

We derive expressions required in generalizing the Gutzwiller approximation to models comprising arbitrarily degenerate localized orbitals.

Jae Dong Noh, Doochul Kim

We investigate the universal property of curvatures in surface models which display a flat phase and a rough phase whose criticality is described by the Gaussian model. Earlier we derived a relation between the Hessian of the free energy and the Gaussian coupling constant in the six-vertex model. Here we show its validity in a general setting using renormali

Beom Jun Kim, Jeenu Kim, Sung Yong Park, M. Y. Choi

We investigate quantum phase transitions in two-dimensional superconducting arrays with general capacitance matrices and discrete charge states. We use the perturbation theory together with the simulated annealing method to obtain the zero-temperature phase diagrams, which display various lobe-like structures of insulating solid phases, and examine the possi

Arjendu Pattanayak, William Schieve

We apply the approximate dynamics derived from the Gaussian time-dependent variational principle to the Hamiltonian $ \hat H= {1/2}(\hat p_x ^2+ \hat p_y ^2)+ {1/2}\hat x^2\hat y^2$, which is strongly chaotic in the classical limit. We are able to calculate, essentially analytically, low-lying eigenvalues for this system. These approximate eigenvalues agree

A. Celani, R. Prandi, G. Boffetta

The analogue of the Kolmogorov's four-fifths law is derived for two-dimensional, homogeneous, isotropic EMHD turbulence in the energy cascade inertial range. Direct numerical simulations for the freely decaying case show that this relation holds true for different values of the adimensional electron inertial length scale, $d_e$. The energy spectrum is fo

Marco Spaans, David A. Neufeld

We have constructed three-dimensional models for the equilibrium abundance of molecular hydrogen within diffuse interstellar clouds of arbitrary geometry that are illuminated by ultraviolet radiation. The position-dependent photo- dissociation rate of H$_2$ within such clouds was computed using a 26-ray approximation to model the attenuation of the incident

David A. Neufeld, James M. Stone

We have modeled the gas temperature structure in unstable C-type shocks and obtained predictions for the resultant CO and H2 rotational line emissions, using numerical simulations of the Wardle instability that were carried out by Stone (1997) and that have been described in a companion paper. We obtained results for the gas temperature distribution in -- an

S. Castro, R. M. Rich, M. Grenon, B. Barbuy

We report detailed analysis of high-resolution spectra of nine high velocity metal-rich dwarfs in the solar neighborhood. The stars are super metal-rich and 5 of them have [Fe/H]>=+0.4, making them the most metal-rich stars currently known. We find that alpha-elements decrease with increasing metallicity; s-elements are underabundant by about [s-elements/Fe]

R. J. Allen, J. H. Knapen, R. Bohlin, T. Stecher

We compare the detailed distributions of HI, H alpha, and 150 nm far-UV continuum emission in the spiral arms of M81 at a resolution of 9" (linear resolution 150 pc at 3.7 Mpc distance). The bright H alpha emission peaks are always associated with peaks in the far-UV emission. The converse is not always true; there are many regions of far-UV emission wit

S. P. Goodwin, J. Gribbin, M. A. Hendry

It has been thought for many years that the Milky Way is an overly large spiral galaxy. Using Cephied distances to 17 spiral galaxies we calculate the true linear diameters of those galaxies. These diameters are then compared to that of the Milky Way which is found to be, at most, an averagely sized spiral galaxy. When compared to galaxies of approximately t

I. Semeniuk, A. Olech, T. Kwast, M. Nalezyty

We present CCD R photometry of SW Ursae Majoris - an SUUMa type cataclysmic variable - obtained during its April 1996 superoutburst. The mean value of the superhump period derived from our observations is 0.05818(+/-2) days (83.8 min). The analysis of times of superhump maxima gives clear evidence for the increase of the superhump period with dPsh/dt=0.00008

Gordon Baym, H. Heiselberg

We calculate the electrical conductivity in the early universe at temperatures below as well as above the electroweak vacuum scale, $T_c\simeq 100$GeV. Debye and dynamical screening of electric and magnetic interactions leads to a finite conductivity, $σ_{el}\sim T/α\ln(1/α)$, at temperatures well below $T_c$. At temperatures above, $W^\pm$ charge-exchange p

Cheongho Han

The biggest uncertainty in determining microlensing parameters comes from the blending of source star images because the current experiments are being carried out toward very dense star fields: the Galactic bulge and Magellanic Clouds. The experiments try to correct the blending effects for individual events by introducing an additional lensing parameter, th

Zong-Hong Zhu, Xiang-Ping Wu

Very deep galaxy surveys have revealed a considerably large population of faint galaxies, which leads to the speculation that all distant objects are moderately magnified by the gravitational lensing effects of galaxies (Fried 1997). In this letter, we present a simple estimate of the lensing amplitudes by all galaxies up to redshift $z=2$ in terms of galaxy

Matthew G. Baring, Alice K. Harding

The splitting of photons in the presence of an intense magnetic field has recently found astrophysical applications in polar cap models of gamma-ray pulsars and in magnetar scenarios for soft gamma repeaters. Numerical computation of the polarization-dependent rates of this third order QED process for arbitrary field strengths and energies below pair creatio

D. L. Tucker, G. Hasinger, H. Lin

The Las Campanas Redshift Survey, an optically selected survey which contains 26,418 galaxy redshifts, has been correlated with ``The First ROSAT Source Catalogue of Pointed Observations with the PSPC,'' which contains 50,408 sources from 2876 ROSAT pointed observations. Ten matches were found. The optical spectra of most of the ten matches show weak

Stephen D. H. Hsu

We resolve an ambiguity in the sign of the gaugino determinant in supersymmetric models. The result, that the gaugino determinant can be taken positive for all background gauge configurations, is necessary for application of QCD inequalities and lattice Monte Carlo methods to supersymmetric Yang-Mills models.

G. S. Bisnovatyi-Kogan, R. V. E. Lovelace

Advection-dominated, high-temperature, quasi-spherical accretion flow onto a compact object, recently considered by a number of authors, assume that the dissipation of turbulent energy of the flow heats the ions and that the dissipated energy is advected inward. It is suggested that the efficiency of conversion of accretion energy to radiation can be very mu

Louis Crane

We propose a model for the quantum theory of gravity. the model has diffeomorphism invariance, a natural length scale, and (plausibly) propagating modes. in the new addendum, we alter the model in a way which makes the propagating modes much easier to approach.

Alexander L. Fetter, David L. Feder

Corrections to the zero-temperature Thomas-Fermi description of a dilute interacting condensed Bose-Einstein gas confined in an isotropic harmonic trap arise due to the presence of a boundary layer near the condensate surface. Within the Bogoliubov approximation, the various contributions to the ground-state condensate energy all have terms of order R^{-4}ln

ZEUS Collaboration

Inclusive photoproduction of D*+- in ep collisions at HERA has been measured with the ZEUS detector for photon-proton centre of mass energies in the range 115 < W < 280 GeV and photon virtuality Q**2 < 4 GeV**2. The cross section sigma(ep --> D*X) integrated over the kinematic region pt(D*) > 3 GeV and -1.5 < eta(D*) < 1.0 is (10.6+-1.7(stat.)+1.6(syst.)-1.3

Michael Lashkevich

The scaling limit of the spectrum, $S$ matrix, and of the form factors of the polarization operator in the six vertex model has been found. The result for the form factors is consistent with the form factors of the sine-Gordon model found recently by Lukyanov. We discuss the origin of the structure of the free field representation for the sine-Gordon model a

W. A. Sabra

We present dyonic BPS static black hole solutions for general d=4, N=2 supergravity theories coupled to vector and hypermultiplets. These solutions are generalisations of the spherically symmetric Majumdar-Papapetrou black hole solutions of Einstein-Maxwell gravity and are completely characterised by a set of constrained harmonic functions. In terms of the u

D. Poilblanc, S. Yunoki, S. Maekawa, E. Dagotto

The effects of a long range electronic potential on a one dimensional commensurate Charge Density Wave (CDW) state are investigated. Using numerical techniques it is shown that a transition to a metallic ground state is reached as the range of the electron-electron repulsion increases. In this metallic state, the optical conductivity exhibits a large Drude w

Frank Morawietz, Tom Cornell

In this paper we describe an approach to constraint-based syntactic theories in terms of finite tree automata. The solutions to constraints expressed in weak monadic second order (MSO) logic are represented by tree automata recognizing the assignments which make the formulas true. We show that this allows an efficient representation of knowledge about the co

Takeshi Chiba, Naoshi Sugiyama, Takashi Nakamura

Motivated by the possibility of $H_0t_0 > 1$ where $H_0$ and $t_0$ are the Hubble parameter and the age of the universe, respectively, we investigate the cosmology including x-matter. x-matter is expressed by the equation of state $p_x=w_0ρ_{x0} + c_s^2(ρ_x-ρ_{x0})$, where $p_x$, $ρ_x$ and $ρ_{x0}$ are the pressure, the density of x-matter and the density at

Michael B. Green, Pierre Vanhove

The R^4 terms in the effective action for M-theory compactified on a two-torus are motivated by combining one-loop results in type II superstring theories with the Sl(2,Z) duality symmetry. The conjectured expression reproduces precisely the tree-level and one-loop R^4 terms in the effective action of the type II string theories compactified on a circle, tog

Carsten Wengel, A. Peter Young

We present a Monte Carlo study of the d=3 gauge glass and the XY--spin glass models in the vortex representation. We investigate the critical behavior of these models by a scaling analysis of the linear resistivity and current-- voltage characteristics, both in the limits of zero and strong screening of the vortex-interactions. Without screening, both models

Chao-Hsi Chang, Cong-Feng Qiao, Jian-Xiong Wang

J/\psi production associated with a hard photon in e^+e^- annihilation, being of QED nature, is invastigated thoroughly in the paper. To show its influence on the observation of the color-octet singnature in the e^+e^- annihilation via J/\psi inclusive production, the cross sections of the J/\psi productions through different mechanisms at various energies a

John K. Elwood, Alon E. Faraggi

The H1 and ZEUS collaborations have recently reported a significant excess of events at high $Q^2$ in positron-proton collisions. While there exists insufficient data to conclusively determine the origin of this excess, one possibility is that it is due to a new leptoquark at mass scale around 200 GeV. We examine the type of leptoquark states that exist in s

O. V. Kaptsov, Yu. V. Shan&#39;ko

In the paper we present a trilinear form and a Darboux-type transformation to an equation considered by Tzitzeica in 1910. This equation equivalent to the Bullough-Dodd-Jiber-Shabat equation. Soliton solutions are constructed by dressing the trivial solution.

Lev S. Tsimring

Mean flow effects are discussed for two different pattern-forming systems: Rayleigh-Benard convection and Faraday instability in viscous fluid. In both systems spirals are observed in certain parameter regions. In the Rayleigh-Benard convection, the spiral core instability and subsequent generation of up- and downflow hexagons are shown to occur due to the m

Francois Drolet, Jorge Vinals

We study the effect of external stochastic modulation on a system with O(2) symmetry that exhibits a Hopf or oscillatory instability in the absence of modulation. The study includes a random component in both the control parameter of the bifurcation and in the modulation amplitude. Stability boundaries are computed by either solving the stationary Fokker-Pla

A. B. Kaidalov, A. P. Krutenkova

The inclusive pion double charge exchange process on nuclei is considered in the framework of the Gribov-Glauber approach. It is shown that inelastic rescatterings related to production of two (and more) pions in the intermediate state give an important contribution to the process of double charge exchange at kinetic energies above ~ 0.5 GeV. This mechanism

Q. H. Zhang, U. A. Wiedemann, C. Slotta, U. Heinz

A simple new algorithm for the calculation of two-particle Bose-Einstein correlations from classical event generators is derived and discussed.

Andrzej Z. Gorski, S. Drozdz

Multifractal scaling analysis of nuclear giant resonance transition probability distributions is performed within the approximation which takes into account the one-particle-one-hole (1p-1h) and 2p-2h states. A new measure to determine the fractal dimensions of the spectra is introduced. It is found that chaotic dynamics governing the decay leads to non-triv

Spiros A. Argyros, Irene Deliyanni, Denka Kutzarova, A. Manoussakis

We study the modified and boundedly modified mixed Tsirelson spaces $T_M[({\cal F}_{k_n},θ_n)_{n=1}^{\infty }]$ and $T_{M(s)}[({\cal F}_{k_n},θ_n)_{n=1}^{\infty }]$ respectively, defined by a subsequence $({\cal F}_{k_n})$ of the sequence of Schreier families $({\cal F}_n)$. These are reflexive asymptotic $\ell_1$ spaces with an unconditio- nal basis $(e_i)_

Ivan G. Avramidi

The heat kernel associated with an elliptic second-order partial differential operator of Laplace type acting on smooth sections of a vector bundle over a Riemannian manifold, is studied. A general manifestly covariant method for computation of the coefficients of the heat kernel asymptotic expansion is developed. The technique enables one to compute explici

Michael R. Douglas, Brian R. Greene, David R. Morrison

We study topological properties of the D-brane resolution of three-dimensional orbifold singularities, C^3/Gamma, for finite abelian groups Gamma. The D-brane vacuum moduli space is shown to fill out the background spacetime with Fayet--Iliopoulos parameters controlling the size of the blow-ups. This D-brane vacuum moduli space can be classically described b

David H. Adams

A new discretisation of a doubled, i.e. BF, version of the pure abelian Chern-Simons theory is presented. It reproduces the continuum expressions for the topological quantities of interest in the theory, namely the partition function and correlation function of Wilson loops. Similarities with free spinor field theory are discussed which are of interest in co

Leopoldo A. Pando Zayas

We show how different modifications of Kantowski-Sachs cosmologies emerge in four dimensions as dimensional reduction of the gauged Wess-Zumino-Witten model based on $SO(2,2)/SO(2)$.

S. Esposito

We construct an explicit covariant Majorana formulation of Maxwell electromagnetism which does not make use of vector 4-potential. This allows to write a ``Dirac&#39;&#39; equation for the photon containing all the known properties of it. In particular, the spin and (intrinsic) boost matrices are derived and the helicity properties of the photon are studied.

Antonio Riotto, Ola Tornkvist

We study non-topological and CP-violating static wall solutions in the framework of the Minimal Supersymmetric Standard Model. We show that such membranes, characterized by a non-trivial winding of the relative $U(1)$ phase of the two Higgs fields in the direction orthogonal to the wall, exist for small values of the mass of the CP-odd Higgs boson when loop

Zoltan Ligeti

Uncertainties in the theoretical prediction for the inclusive $\bar B\to X_sγ$ decay rate are examined. Certain nonperturbative effects involving a virtual $c\bar c$ loop, which are calculable using the operator product expansion, are discussed.

Yuri V. Kovchegov, A. H. Mueller, Samuel Wallon

Unitarity corrections to the BFKL description of high energy hard scattering are viewed in large $N_c$ QCD in light-cone quantization. In a center of mass frame unitarity corrections to high energy hard scattering are manifestly perturbatively calculable and unrelated to questions of parton saturation. In a frame where one of the hadrons is initially at rest

Stefan Dittmaier

The radiative corrections to Compton scattering vanish in the low-energy limit in all orders of perturbation theory. This theorem, which is well-known for Abelian gauge theories, is proved in the electroweak Standard Model. Moreover, analogous theorems are derived for photon scattering off other charged particles, in particular W bosons. Since the theorems f

Andreas Blumhofer, Johannes Manus

We present a new method solving Schwinger-Dyson equations in gauge theories via imaginary part analysis. The self-consistency equation for the fermion self-energy can be reduced from a numerical unstable eigenvalue problem to a finite dimensional integral which can be solved easily. We can therefore derive relations between the dynamically generated fermion

Laura Covi, Nuria Rius, Esteban Roulet, Francesco Vissani

We compute the CP violating decay asymmetries relevant for baryogenesis scenarios involving the out of equilibrium decays of heavy particles, including the finite temperature effects arising from the background of light thermal particles which are present during the decay epoch. Thermal effects can modify the size of CP violation by a sizeable fraction in th

R. Horvat

Finite-temperature and -density radiative corrections to the neutrino effective potential in the otherwise CP-symmetric early Universe are considered in the real-time approach of Thermal Field Theory. A consistent perturbation theory endowed with the hard thermal loop resummation techniques developed by Braaten and Pisarski is applied. Special attention is f

Michael Chavel

A mean field analysis of finite density QCD is presented including the effects of additional chiral invariant four-fermion interactions. A lattice regularization is used with N_f=4 flavors of staggered fermions. The use of the four-fermion coupling as an improved extrapolation parameter over the bare quark mass in Monte Carlo simulations is discussed. Partic

Ferenc Niedermayer

Cluster algorithms for classical and quantum spin systems are discussed. In particular, the cluster algorithm is applied to classical O(N) lattice actions containing interactions of more than two spins. The performance of the multi-cluster and single--cluster methods, and of the standard and improved estimators are compared. (Lecture given at the summer scho

Jose-Luis Rosales, Jose-Luis Sanchez-Gomez

We argue that, in order to obtain decoherence of spacetime, we should consider quantum conformal metric fluctuations of spacetime. This could be the required environment in the problem of selfmeasurement of spacetime in quantum gravity.

S. Antoci, L. Mihich

Given the present status of the problem of the electromagnetic energy tensor in matter, there is perhaps use in recalling a forgotten argument given in 1923 by W. Gordon. Let us consider a material medium which is homogeneous and isotropic when viewed in its rest frame. For such a medium, Gordon&#39;s argument allows to reduce the above mentioned problem to

Johan Kustermans

In this paper, we describe a natural method to extend left invariant weights on C*-algebraic quantum groups. This method is then used to improve the left invariance property of a left invariant weight. We also prove some kind of uniqueness result for left Haar weights on C*-algebraic quantum groups arising from algebraic ones.

Johan Kustermans

In the first part of this paper, we implement the multiplier algebra of the dual of an algebraic quantum group (A,Delta) as a space of linear functionals on A. In the second part, we construct the universal corepresentation of (A,Delta) and use it to prove a bijective correspondence between corepresentations of (A,Delta) and homomorphisms on the dual.

Robert E. Rudd, Warren E. Pickett

We describe a novel superconducting phase that arises due to a pairing instability of the half-metallic antiferromagnetic (HM AFM) normal state. This single spin superconducting (SSS) phase contains broken time reversal symmetry in addition to broken gauge symmetry, the former due to the underlying magnetic order in the normal state. A classification of norm

Mehran Kardar

The lectures examine several problems related to non-equilibrium fluctuations of interfaces and flux lines. The first two introduce the phenomenology of depinning, with particular emphasis on interfaces and contact lines. The role of the anisotropy of the medium in producing different universality classes is elucidated. The last two lectures focus on the dyn

P. B. Sunil Kumar, Madan Rao

We study the shape dynamics of a two-component fluid membrane, using a dynamical triangulation monte carlo simulation and a Langevin description. Phase separation induces morphology changes depending on the lateral mobility of the lipids. When the mobility is large, the familiar labyrinthine spinodal pattern is linearly unstable to undulation fluctuations an

German Rigau, Jordi Atserias, Eneko Agirre

This paper presents a method to combine a set of unsupervised algorithms that can accurately disambiguate word senses in a large, completely untagged corpus. Although most of the techniques for word sense resolution have been presented as stand-alone, it is our belief that full-fledged lexical ambiguity resolution should combine several information sources a

Glen D. Granzow, Hermann Riecke

Defect-chaos is studied numerically in coupled Ginzburg-Landau equations for parametrically driven waves. The motion of the defects is traced in detail yielding their life-times, annihilation partners, and distances traveled. In a regime in which in the one-dimensional case the chaotic dynamics is due to double phase slips, the two-dimensional system exhibit

J. G. Skibo, W. N. Johnson, J. D. Kurfess, R. L. Kinzer

We present the results of OSSE observations of the soft gamma ray continuum emission from the Galactic plane at longitude 95 degrees. Emission is detected between 50 and 600 keV where the spectrum is fit well by a power law with photon index -2.6+-0.3 and flux (4.0+-0.5) 10^{-2} photons/s/cm^2/rad/MeV at 100 keV. This spectral shape in this range is similar

David L. Band

Gamma-ray burst spectra usually show hard-to-soft evolution within intensity spikes and from spike to spike. The techniques used to study spectral evolution often lack sufficient temporal resolution to determine the nature of this evolution. By comparing the auto- and crosscorrelations between the time histories of the BATSE Large Area Detector discriminator

D. Fargion

We show that the expected $ ν_τ $ signals, by their secondary tau tracks, in Km^3 detectors at highest cosmic ray energy window $ 1.7\cdot 10^{21} eV \gt E_τ \gt 1.6 x 10^{17} eV$, must overcome the corresponding $ ν_μ $ (or muonic) ones. Indeed, the Lorentz-boosted tau range length grows (linearly) above muon range, for $ E_τ \RAISE 1.6 x 10^8 GeV$ and reac

Guenter Sigl, Martin Lemoine, Angela V. Olinto

We present a numerical code designed to conduct a likelihood analysis for clusters of nucleons above 10**19 eV originating from discrete astrophysical sources such as powerful radio galaxies, gamma-ray bursts or topological defects. The code simulates the propagation of nucleons in a large-scale magnetic field and constructs the likelihood of a given observe

Martin Lemoine, Guenter Sigl, Angela V. Olinto, David N. Schramm

Protons of energies up to 10**20 eV can be subject to significant deflection and energy dependent time delay in lage scale extragalactic or halo magnetic fields of strengths comparable to current upper limits. By performing 3-dimensional Monte Carlo simulations of nucleon propagation, we show how observations of arrival direction and time distributions can b