December 1999 arXiv papers — page 12

Jen-Chieh Peng

Various QCD tests using recent results from fixed-target dimuon production experiments at Fermilab are discussed. We emphasize that clear evidence for scaling-violation in the Drell-Yan process remains to be established. Further experimental and theoretical work are needed to understand the polarization of the Drell-Yan pairs. The nuclear medium effects for

M. N. Chernodub, F. V. Gubarev, M. I. Polikarpov, V. I. Zakharov

Within the (dual) Abelian Higgs model, confining strings do not disappear at small distances but rather become short strings. In compact 3D electrodynamics, as we argue here, the confining strings are also manifested at small distances in unusual power corrections, disobeying the standard rules of the Operator Product expansion. In the most interesting case

Yigal Shamir

We discuss two modifications of domain-wall fermions, aimed to reduce the chiral-symmetry violations presently encountered in numerical simulations.

H. Neuberger

Within the overlap framework, I derive the main formulae one finds today in papers touting a ``new approach'' to the regularization of chiral gauge theories. My main objective is to clear up an unhealthy confusion about how many successful approaches to regulate chiral fermions on the lattice there really are: At the moment, there is only one, the ov

J. Engelfried

In this course we will give examples for experimental techniques used in particle physics experiments. After a short introduction, we will discuss applications in silicon microstrip detectors, wire chambers, and single photon detection in Ring Imaging Cherenkov (RICH) counters. A short discussion of the relevant physics processes, mainly different forms of e

L. Chkhaidze, T. Djobava, L. Kharkhelauri

The transverse momentum technique is used to analyse charged-particle exclusive data in the central C-Ne and C-Cu interactions at energy of 3.7 Gev per nucleon. The clear evidence of in-plane and out-of-plane (squeeze-out) flow effects for protons and $π^{-}$ mesons have been obtained. In C-Ne interactions the $π^{-}$ mesons in-plane flow is in the same dire

T. R. Mongan

An N + 1 dimensional quantum mechanical model for the origin of the universe results in a 58 e-fold inflation and a cosmological constant/vacuum energy density of the same order of magnitude as the critical density.

L. C. Garcia de Andrade

Fluctuations on de Sitter solution of Einstein-Cartan field equations are obtained in terms of the matter density primordial density fluctuations and spin-torsion density and matter density fluctuations obtained from COBE data. Einstein-de Sitter solution is shown to be unstable even in the absence of torsion.The spin-torsion density fluctuation to generate

S. O. Alexeyev, A. V. Toporensky, V. O. Ustiansky

We investigate FRW cosmological solutions in the theory of modulus field coupled to gravity through a Gauss-Bonnet term. The explicit analytical forms of nonsingular asymptotics are presented for power-law and exponentially steep modulus coupling functions. We study the influence of modulus field potential on these asymptotical regimes and find some forms of

Moncy V. John, K. Babu Joseph

Recent measurements require modifications in conventional cosmology by way of introducing components other than ordinary matter into the total energy density in the universe. On the basis of some dimensional considerations in line with quantum cosmology, Chen and Wu [W. Chen and Y. Wu, Phys. Rev. D 41, 695 (1990)] have argued that an additional component, wh

Michael Bachmann, Hans-Jurgen Schmidt

We solve the Wheeler-DeWitt equation for the minisuperspace of a cosmological model of Bianchi type I with a minimally coupled massive scalar field $ϕ$ as source by generalizing the calculation of Lukash and Schmidt [1]. Contrarily to other approaches we allow strong anisotropy. Combining analytical and numerical methods, we apply an adiabatic approximation

E. K. Lenzi, L. C. Malacarne, R. S. Mendes

Feynman's path integral is herein generalized to the nonextensive canonical density matrix based on Tsallis entropy. This generalization is done in two ways by using unnormalized and normalized constraints. Firstly, we consider the path integral formulation with unnormalized constraints, and this generalization is worked out through two different ways, w

R. Folch, J. Casademunt, A. Hernandez-Machado

We show that a minimal model for viscous fingering with a nematic liquid crystal in which anisotropy is considered to enter through two different viscosities in two perpendicular directions can be mapped to a two-fold anisotropy in the surface tension. We numerically integrate the dynamics of the resulting problem with the phase-field approach to find and ch

O. E. Raichev, P. Vasilopoulos

The Coulomb drag between parallel, {\it ballistic} quantum wires is studied theoretically in the presence of a perpendicular magnetic field B. The transresistance R_D shows peaks as a function of the Fermi level and splitting energy between the 1D subbands of the wires. The sharpest peaks appear when the Fermi level crosses the subband extrema so that the Fe

D. J. Dean, M. R. Strayer, J. C. Wells

We describe computational methods for the theoretical study of explicit correlations beyond the mean field in excitons confined in semiconductor quantum dots in terms of the Auxiliary-Field Monte Carlo (AFMC) method. Using AFMC, the many-body problem is formulated as a Feynman path integral at finite temperatures and evaluated to numerical precision. This ap

C. Furtlehner

We consider an electron coupled to a random magnetic field with local correlations and eventually non-zero average value. Starting from the source-term formalism of Levine, Libby and Pruisken, we define a generating function for static transport coefficients. We use a non-hermitian representation of the Hamiltonian, and a functionnal representation of the ge

Victor M. Perez-Garcia, Juan J. Garcia-Ripoll

We study the stability and dynamics of vortices in two-species condensates using a two mode model. The recent experimental results obtained at JILA (M. R. Matthews, {\em et al.}, Phys. Rev. Lett. 83 (1999) 2498) and theoretical predictions based on the Gross-Pitaevskii equations are verified. We also make an exhaustive analysis of the stability properties of

I. M. Suslov

The density of states for the Schroedinger equation with a Gaussian random potential is determined by the functional integral corresponding to the phi^4 theory with a `wrong' sign of the interaction constant. The special role of the dimension d=4 for such a problem can be seen from different viewpoints but is fundamentally determined by the renormalizabi

A. M. Tsvelik, C. I. Ventura, .

We have studied the energy spectrum of a one-dimensional Kondo lattice, where the localized magnetic moments have SU(N) symmetry and two channels of conduction electrons are present. At half filling, the system is shown to exist in two phases: one dominated by RKKY-exchange interaction effects, and the other by Kondo screening. A quantum phase transition poi

C. I. Ventura, R. A. Barrio, .

The coherent potential approximation, CPA, is a useful tool to treat systems with disorder. Cluster theories have been proposed to go beyond the translation invariant single-site CPA approximation and include some short range correlations. In this framework one can also treat simultaneously diagonal disorder (in the site-diagonal elements of the Hamiltonian)

Jesper Lykke Jacobsen

We numerically calculate the exponent for the disorder averaged and fixed-sample decay of the energy-energy correlator in the q-state random-bond Potts model. Our results are in good agreement with a two-loop expansion (cond-mat/9910181) around q=2 recently found from perturbative renormalisation group techniques, fulfill the correlation length bound ν>= 2/d

Andreas Franz, Andreas Wallraff, Alexey V. Ustinov

We report systematic measurements of the critical current versus magnetic field patterns of annular Josephson junctions in a wide magnetic field range. A modulation of the envelope of the pattern, which depends on the junction width, is observed. The data are compared with theory and good agreement is found.

Victor M. Perez-Garcia, V. V. Konotop, Juan J. Garcia-Ripoll

We study the effect of nonlocality on the collapse properties of a self-focusing Nonlinear Schrödinger system related to Bose-Einstein condensation problems. Using a combination of moment techniques, time dependent variational methods and numerical simulations we present evidences in support of the hypothesis that nonlocal attractively interacting condensate

K. Noergaard, M. R. Eskildsen, N. H. Andersen, J. Jensen

We have discovered a new antiferromagnetic phase in TmNi2B2C by neutron diffraction. The ordering vector is Q_A = (0.48,0,0) and the phase appears above a critical in-plane magnetic field of 0.9 T. The field was applied in order to test the assumption that the zero-field magnetic structure at Q_F = (0.094,0.094,0) would change into a c-axis ferromagnet if su

Shiro Kawabata

Since the discovery of the Berry phase, there has been much interest in the study of topological effects in the fields of quantum mechanics and condensed matter physics. In this paper we investigate the persistent charge current in mesoscopic disorderd rings and compute the disorder averaged persistent current using the diagrammatic method. We find that with

Somendra M. Bhattacharjee

The opening of the Y-fork - the first step of DNA replication - is shown to be a critical phenomenon under an external force at one of its ends. From the results of an equivalent delocalization in a non-hermitian quantum-mechanics problem we show the different scaling behavior of unzipping and melting. The resultant long-range critical features within the un

Wataru Izumida, Osamu Sakai

Tunneling conductance through two quantum dots, which are connected in series to left and right leads, is calculated by using the numerical renormalization group method. As the hopping between the dots increases from very small value, the following states continuously appear; (i) Kondo singlet state of each dot with its adjacent-site lead, (ii) singlet state

T. Munehisa, Y. Munehisa

We report an attempt to calculate energy eigenvalues of large quantum systems by the diagonalization of an effectively truncated Hamiltonian matrix. For this purpose we employ a specific way to systematically make a set of orthogonal states from a trial wavefunction and the Hamiltonian. In comparison with the Lanczos method, which is quite powerful if the si

W. O. Putikka, M. U. Luchini

From calculations of the high temperature series for the free energy of the two-dimensional t-J model we construct series for ratios of the free energy per hole. The ratios can be extrapolated very accurately to low temperatures and used to investigate phase separation. Our results confirm that phase separation occurs only for J/t greater than 1.2. Also, the

I. Ispolatov, P. L. Krapivsky

We study a system of particles moving on a line in the same direction. Passing is allowed and when a fast particle overtakes a slow particle, it acquires a new velocity drawn from a distribution P_0(v), while the slow particle remains unaffected. We show that the system reaches a steady state if P_0(v) vanishes at its lower cutoff; otherwise, the system evol

K. Morita, K. Miyake

It is investigated, on the basis of the fluctuation exchange approximation, how the shape of the Fermi surface is modified in two-dimensional $t-t'-U$ Hubbard model at half filling as strength of the onsite Coulomb interaction $U$ is increased. The antiferromagnetic (AF) correlation length is shown to be enhanced as the Coulomb interaction get closer to

V. Karimipour

We will prove certain general relations in Matrix Product Ansatz for one dimensional stochastic systems, which are true in both random and sequential updates. We will derive general MPA expressions for the currents and current correlators and find the conditions in the MPA formalism, under which the correlators are site-independent or completely vanishing.

Nevin Weinberg, M. Coleman Miller, Donald Q. Lamb

Many thermonuclear X-ray bursts exhibit brightness oscillations. The brightness oscillations are thought to be due to the combined effects of non-uniform nuclear burning and rotation of the neutron star. The waveforms of the oscillations contain information about the size and number of burning regions. They also contain substantial information about the mass

J. Christopher Howk, Joseph Cassinelli, Jon Bjorkman, Henny Lamers

Observations of the B0.2V star tau Scorpii have revealed unusual stellar wind characteristics: red-shifted absorption in the far-ultraviolet O VI resonance doublet up to +250 km/s, and extremely hard X-ray emission implying gas at temperatures in excess of 10^7 K. We describe a phenomenological model to explain these properties. We assume the wind of tau Sco

O. V. Verkhodanov, A. I. Kopylov, O. P. Zhelenkova, N. V. Verkhodanova

The project of the informational system creation on the problem of evolution of radio galaxies is described. This system, being developed at present, will allow a user to operate with simulated curves of spectral energy distributions (SED) and to estimate ages and redshifts by photometrical data. Authors use SEDs of several models (GISSEL'96 (Bruzual, Ch

In-Saeng Suh, G. J. Mathews

Recently, neutron stars with very strong surface magnetic fields have been suggested as the site for the origin of observed soft gamma repeaters (SGRs). We investigate the influence of a strong magnetic field on the properties and internal structure of such strongly magnetized neutron stars (magnetars). The presence of a sufficiently strong magnetic field ch

Detlef Schoenberner, Matthias Steffen

We discuss the basic physical model and the relevant processes responsible for creating and shaping planetary nebulae out of a cool AGB wind envelope. We show that a hydrodynamical treatment along the upper AGB leads quite naturally to more realistic starting configurations for planetaries with density slopes steeper than r^{-2}. Taking into account photoion

Cristiano Palomba

We derive new upper limits on the ellipticity of pulsars whose braking index has been measured, more tightening than those usually given, assuming that both a gravitational torque and an electromagnetic one act on them. We show that the measured braking indexes of pulsars are recovered in this model. We consider the electromagnetic torque both constant and v

A. Golden, A. Shearer, G. M. Beskin

Based on observations of the Crab pulsar using the TRIFFID high speed imaging photometer in the UBV bands using the Special Astrophysical Observatory's 6m telescope in the Russian Caucasus, we report the detection of pronounced emission during the so-called `off' phase of emission. Following de-extinction, this unpulsed component of emission is shown

P. N. Best, H. J. A. R"ottgering, M. D. Lehnert

A new sample of very powerful radio sources, defined from the Molonglo Reference Catalogue, was recently compiled by Best, Rottgering and Lehnert (1999). These authors provided redshifts for 174 of the 178 objects in the sample, making the sample 98% spectroscopically complete. Here, redshifts for three of the remaining galaxies are presented, confirming the

Falk Herwig

Recent advances in constructing stellar evolution models of hydrogen-deficient post-asymptotic giant branch (AGB) stars are presented. Hydrogen-deficiency can originate from mixing and subsequent convective burning of protons in the deeper layers during a thermal pulse on the post-AGB (VLTP). Dredge-up alone may also be responsible for hydrogen-deficiency of

A. C. Baker, G. P. Mathlin, D. K. Churches, M. G. Edmunds

We are encouraged by the improving abundance measurements for quasar damped absorption line systems to start a new study of galaxy chemical evolution from high to low redshifts. Our goal is a simple, robust model based on a synthesis of our best understanding of the relevant physics, such as cosmology, large-scale structure formation, galaxy collapse, star f

Felix Ryde, Roland Svensson

For the first time, the consequences of combining two well-established empirical relations, describing different aspects of the spectral evolution of observed gamma-ray burst (GRB) pulses, are explored. These empirical relations are: i) the hardness-intensity correlation, and ii) the hardness-photon fluence correlation. From these we find a self-consistent,

Falk Herwig, Thomas Bloecker, Thomas Driebe

We give a brief review on the properties of asymptotic giant branch models with overshoot. Then we describe new model calculations with overshoot. Initial masses are ranging from 1 to 3Msun and metallicities are Z=0.02, 0.01 and 0.001. Third dredge-up occurs efficiently for low masses and carbon stars are formed, with some at core masses as low as 0.58Msun.

Andrew R Liddle, Anupam Mazumdar

We make a detailed calculation of the amplitude of isocurvature perturbations arising from inflationary models in which the cold dark matter is represented by a scalar field which acquires perturbations during inflation. We use this to compute the normalization to large-angle microwave background anisotropies. Unlike the case of adiabatic perturbations, the

A. Pappa, I. Georgantopoulos, G. C. Stewart

We present ROSAT HRI and ASCA observations of the well known ULIRG IRAS19254-7245 (the Superantennae). The object is not detected by ROSAT yielding a 3σupper limit of L_x ~8x10^{41} erg/s in the 0.1-2 keV band. However, we obtain a clear detection by ASCA yielding a luminosity in the 2-10 keV band of 2 \times 10^{42}erg/s. Its X-ray spectrum is very hard, eq

Martin J. Rees

The existence of supermassive collapsed objects in the cores of most galaxies poses still-unanswered questions. First, how did they form, and how does their mass depend on the properties of the host galaxy? Second, can observations probe the metric in the strong-field domain, testing whether it indeed agrees with the Kerr geometry predicted by general relati

Martin J. Rees

The universe would have been completely dark between the epoch of recombination and the development of the first non-linear structure. But at redshifts beyond 5 -- perhaps even beyond 20 -- stars formed within `subgalaxies' and created the first heavy elements; these same systems (together perhaps with `miniquasars') generated the UV radiation that i

Giorgio Matt, Fulvio Pompilio, Fabio La Franca

A synthesis model for the cosmic X-ray Background (XRB) is presented, which includes a proper treatment of Compton scattering in the absorbing matter for type 2 AGN. Evidence for a decrease of the relative importance of type 2 AGN at high redshift is found, which may be due either to a decrease of the relative number of obscured sources, or (more plausibly)

Dominik J. Schwarz, Stefan Hofmann

We investigate the clumping of cold dark matter (CDM) at small scales. If the CDM particle is the neutralino, we find that collisional damping during its kinetic decoupling from the radiation fluid and free streaming introduce a small-scale cut-off in the primordial power spectrum of CDM. This cut-off sets the scale for the very first CDM objects in the Univ

Y. Q. Chen, P. E. Nissen, G. Zhao, H. W. Zhang

High resolution, high S/N spectra have been obtained for a sample of 90 F and G main-sequence disk stars covering the metallicity range -1.0 < [Fe/H] < +0.1, and have been analysed in a parallel way to the work of Edvardsson et al. (1993). Effective temperatures are based on the Alonso et al. (1996) calibration of color indices and surface gravities are calc

Paola Marigo

We present new sets of chemical yields from low- and intermediate-mass stars with 0.8 Msun <= M <= Mup ~ 5 Msun, and three choices of the metallicity, Z=0.02, Z=0.008, and Z=0.004 (Marigo 2000, in preparation). These are then compared with the yields calculated by other authors on the basis of different model prescriptions, and basic observational constraint

Heino Falcke, Andrew S. Wilson, Christian Henkel, Andreas Brunthaler

We present HST/WFPC2 images in Halpha+[NII]6548,6583 lines and continuum radiation and a VLA map at 8 GHz of the H2O gigamaser galaxy TXS2226-184. This galaxy has the most luminous H2O maser emission known to date. Our red continuum images reveal a highly elongated galaxy with a dust lane crossing the nucleus. The surface brightness profile is best fitted by

P. M. Ricker, S. Dodelson, D. Q. Lamb

We describe a new hybrid N-body/hydrodynamical code based on the particle-mesh (PM) method and the piecewise-parabolic method (PPM) for use in solving problems related to the evolution of large-scale structure, galaxy clusters, and individual galaxies. The code, named COSMOS, possesses several new features which distinguish it from other PM-PPM codes. In par

W. D. Li, A. V. Filippenko, A. G. Riess, J. Y. Hu

We have compiled a sample of 90 SNe Ia from 1997 to 1999 (up to SN 1999da) and studied the peculiarity rate of SN 1991T, SN 1991bg and SN 1986G-like objects. A Monte Carlo code is written to study the observational biases involved in the evaluation of the intrinsic peculiarity rate of SNe Ia. We found that the peculiarity rate of SNe Ia is higher than 30% an

Douglas C. Leonard, Alexei V. Filippenko, Thomas Matheson

We present results from a spectropolarimetric survey of young supernovae completed at the Keck Observatory, including at least one example from each of the major supernova types: Ia (1997dt), Ib (1998T, 1997dq), Ib/c-pec (1997ef), IIn (1997eg), and II-P (1997ds). All objects show evidence for intrinsic polarization, suggesting that asphericity may be a commo

W. D. Li, A. V. Filippenko, R. R. Treffers, A. Friedman

We report here the current status of the Lick Observatory Supernova Search (LOSS) with the Katman Automatic Imaging Telescope (KAIT). The progress on both the hardware and the software of the system is described, and we present a list of recent discoveries. LOSS is the world&#39; most successful search engine for nearby supernovae.

Marek Sikora, Greg Madejski

X-ray observations of blazars associated with the OVV (Optically Violently Variable) quasars put strong constraints on the electron - positron pair content of radio-loud quasar jets. From those observations, we infer that jets in quasars contain many more electron - positron pairs than protons, but dynamically are still dominated by protons. In particular, w

Dimitar D. Sasselov

The two nearby galaxies, M31 and M33, are stepping stones for most of our current efforts to understand the evolving universe at large scales. We are undertaking a long term project, called DIRECT, to improve the direct distance estimate to M31 and M33. The massive photometry we have obtained as part of our project over the past 3 years provides us with very

Brad K. Gibson, Philip R. Maloney, Shoko Sakai

We examine the suggestion that half of the HST Key Project- and Sandage/Saha-observed galaxies have had their distances systematically underestimated, by 0.1-0.3 mag in the distance modulus, due to the underappreciated influence of stellar profile blending on the WFC chips. The signature of such an effect would be a systematic trend in (i) the Type Ia supern

Griet C. Van de Steene, Peter R. Wood, Peter A. M. van Hoof

We present H alpha emission line spectra of 7 post-AGB stars. Typically, they have a P-Cygni type profile with a very strong emission component and a relatively narrow absorption component. These lines are formed in the fast post-AGB wind which in most cases has a velocity of around 100 km/s. Hence the emission originates close to the central star and the ab

Tyler Bourke, A. R. Hyland, Garry Robinson, Kevin Luhman

We present new observational data for IRAS 09371+1212, the Frosty Leo Nebula, in the form of infrared spectra from 2.2-2.5 microns which reveal photopheric bands of CO. The ^12CO/^13CO band ratio determined is similar to those exhibited by evolved K giant stars, and supports the proposal that the object is highly evolved. The equivalent width of the CO bands

P. A. M. van Hoof

When measuring diameters of partially resolved sources like planetary nebulae, H II regions or galaxies, often a technique called gaussian deconvolution is used. This technique yields a gaussian diameter which subsequently has to be multiplied with a conversion factor to obtain the true angular diameter of the source. This conversion factor is a function of

W. Hwang, P. L. Krapivsky, S. Redner

We examine the dynamics of an age-structured population model in which the life expectancy of an offspring may be mutated with respect to that of the parent. While the total population of the system always reaches a steady state, the fitness and age characteristics exhibit counter-intuitive behavior as a function of the mutational bias. By analytical and num

T. K. Kuo, Guo-Hong Wu, Sadek W. Mansour

We give a general analysis of neutrino mixing in the seesaw mechanism with three flavors. Assuming that the Dirac and u-quark mass matrices are similar, we establish simple relations between the neutrino parameters and individual Majorana masses. They are shown to depend rather strongly on the physical neutrino mixing angles. We calculate explicitly the impl

C. J. Horowitz, S. J. Pollock, P. A. Souder, R. Michaels

Parity violating electron nucleus scattering is a clean and powerful tool for measuring the spatial distributions of neutrons in nuclei with unprecedented accuracy. Parity violation arises from the interference of electromagnetic and weak neutral amplitudes, and the $Z^0$ of the Standard Model couples primarily to neutrons at low $Q^2$. The data can be inter

J. Lesgourgues, S. Pastor, S. Prunet

We show that even the smallest neutrino mass consistent with the Super--Kamiokande data is relevant for cosmological models of structure formation and cosmic microwave background (CMB) anisotropies, provided that a relic neutrino asymmetry exists. We calculate the precision with which a 0.07 eV neutrino mass could be extracted from CMB anisotropy and large-s

Olaf Lechtenfeld, Alexander Sorin

Three nonequivalent real forms of the complex twisted N=2 supersymmetric Toda chain hierarchy (solv-int/9907021) in real N=1 superspace are presented. It is demonstrated that they possess a global twisted N=2 supersymmetry. We discuss a new superfield basis in which the supersymmetry transformations are local. Furthermore, a representation of this hierarchy

S. J. Gates,, O. Lebedev

We discuss the possibility of the existence of a long-lived top squark ($\tau\ll 10^{10} years$) and its motivation. If the stop is indeed metastable, it forms hadrons. We study properties of the low-energy stop-containing hadrons and their signatures in collider experiments.

Tzuu-Kang Chyi, Chien-Wen Hwang, W. F. Kao, Guey-Lin Lin

The weak-field expansion of the charged fermion propagator under a uniform magnetic field is studied. Starting from Schwinger&#39;s proper-time representation, we express the charged fermion propagator as an infinite series corresponding to different Landau levels. This infinite series is then reorganized according to the powers of the external field strengt

Xiaofeng Guo, Jianwei Qiu, Xiaofei Zhang

Define the nuclear dependence coefficient $α(A,q_T)$ in terms of ratio of transverse momentum spectrum in hadron-nucleus and in hadron-nucleon collisions: $\frac{dσ^{hA}}{dq_T^2}/ \frac{dσ^{hN}}{dq_T^2}\equiv A^{α(A,q_T)}$. We argue that in small $q_T$ region, the $α(A,q_T)$ for the Drell-Yan and J/$ψ$ production is given by a universal function:\ $a+b q_T^2

I. P. Ennes, C. Lozano, S. G. Naculich, H. J. Schnitzer

We give a unified analysis of four-dimensional elliptic models with N=2 supersymmetry and a simple gauge group, and their relation to M-theory. Explicit calculations of the Seiberg-Witten curves and the resulting one-instanton prepotential are presented. The remarkable regularities that emerge are emphasized. In addition, we calculate the prepotential in the

I. Bakas, A. Brandhuber, K. Sfetsos

We provide an algebraic classification of all supersymmetric domain wall solutions of maximal gauged supergravity in four and seven dimensions, in the presence of non-trivial scalar fields in the coset SL(8,R)/SO(8) and SL(5,R)/SO(5) respectively. These solutions satisfy first-order equations, which can be obtained using the method of Bogomol&#39;nyi. From a

S. von Rotz, M. P. Locher, V. E. Markushin

We evaluate three meson doorway mechanisms for nucleon-antinucleon annihilation at rest for the first time. Detailed results are presented for the final state phi pi0 originating from the 3S1 initial state and for the phi rho channel originating from 1S0. The results presented also include the improved contributions from two meson doorway states and from the

Peter Suranyi

A new class of vortex solutions is found in SU(2) gauge theories with two adjoint representation Higgs bosons. Implications of these new solutions and their possible connection with Center Gauge fixed pure gauge theories are discussed.

Harald Fritzsch, Zhi-zhong Xing

We give an overview of recent progress in the study of fermion mass and flavor mixing phenomena. The hints exhibited by the quark and lepton mass spectra towards possible underlying flavor symmetries, from which realistic models of mass generation could be built, are emphasized. A variety of schemes of quark mass matrices at low and superhigh energy scales a

Sergei Y. Sazonov, Rashid A. Sunyaev

The angular distribution of low-frequency radiation after single scattering by an isotropic distribution of relativistic electrons considerably differs from the Rayleigh angular function. In particular, the scattering by an ensemble of ultra-relativistic electrons obeys the law p=1-cos(alpha), where alpha is the scattering angle; hence photons are preferenti

C. J. van der Beek, S. Colson, M. Konczykowski, M. V. Indenbom

Magnetic relaxation in the Bragg-glass phase of overdoped Bi_2Sr_2CaCu_2O_8 crystals was investigated using time-resolved magneto-optical visualisation of the flux distribution. This has permitted us to extract the current-voltage characteristic, which can be well described by a power-law, although fits to a stretched exponential E \sim \exp(- j_{c} / j)^μ w

Kirill A. Kazakov, Petr I. Pronin

The problem of gauge independent definition of effective gravitational field is considered from the point of view of the process of measurement. Under assumption that dynamics of the measuring apparatus can be described by the ordinary classical action, effective Slavnov identities for the generating functionals of Green functions corresponding to a system o

Achim Weiss, Helmut Schlattl

We present a grid of evolutionary calculations for metal-poor low-mass stars for a variety of initial helium and metal abundances. The intention is mainly to provide a database for deriving directly stellar ages of halo and globular cluster stars for which basic stellar parameters are known, but the tracks can also be used for isochrone or luminosity functio

Stephen C. Davis, Warren B. Perkins, Anne-Christine Davis

The stability of fermionic charge carriers on cosmic strings is considered. We show that neutral fermion currents in cosmic strings are always chiral or time-like, in contrast to the case of bosonic currents. The spectrum of bound states on an abelian SO(10) string is determined both before and after the electroweak phase transition. We determine the mass ac

M. B. Barbaro, A. Molinari, F. Palumbo, M. R. Quaglia

The pairing interaction among identical nucleons in a single-particle level is treated in the hamiltonian formalism using even Grassmann variables. A minimal (irreducible) basis having a remarkable symmetry property is set up using composite, commuting variables with a finite index of nilpotency. Eigenvalues and eigenfunctions of given energy, seniority and

R. Kaminski, L. Lesniak, K. Rybicki

We continue the analysis of S-wave production amplitudes for the reaction pi- p -> pi+ pi- n involving the data obtained by the CERN--Cracow-Munich collaboration on a transversely polarized target at 17.2 GeV/c pi- momentum. This study deals with the region below the K - Kbar threshold. In particular, we study the &#34;up-steep&#34; solution containing a nar

S. Chanillo, D. Grieser, M. Imai, K. Kurata

We consider the following eigenvalue optimization problem: Given a bounded domain $Ω\subset\R^n$ and numbers $α\geq 0$, $A\in [0,|Ω|]$, find a subset $D\subsetΩ$ of area $A$ for which the first Dirichlet eigenvalue of the operator $-Δ+ αχ_D$ is as small as possible. We prove existence of solutions and investigate their qualitative properties. For example, we

V. Bernard, H. Krebs, Ulf-G. Meißner

Threshold neutral pion electroproduction on the deuteron is studied in the framework of baryon chiral perturbation theory at next-to-leading order in the chiral expansion. To this order in small momenta, the amplitude is finite and a sum of two- and three-body interactions with no undetermined parameters. We calculate the S-wave multipoles for threshold prod

Juan J. Garcia-Ripoll, Victor M. Perez-Garcia, Elena A. Ostrovskaya, Yuri S. Kivshar

We find a new type of optical vector soliton that originates from trapping of a dipole mode by a soliton-induced waveguide. These solitons, which appear as a consequence of the vector nature of the two component system, are more stable than the previously found optical vortex-mode solitons and represent a new type of extremely robust nonlinear vector structu

Nicola Grillo

Quantum gravity coupled to scalar massive matter fields is investigated within the framework of causal perturbation theory. One-loop calculations include matter loop graviton self-energy and matter self-energy and yield ultraviolet finite and cutoff-free expressions. Perturbative gauge invariance to second order implies the usual Slavnov-Ward identities for

Eric Laenen

I review some topics in the production and decays of heavy flavours that are relevant for collider physics. In particular, I discuss the present status and some recent progress related to masses, parton densities and fragmentation functions of heavy quarks, as well as threshold resummation, polarized onium production at high transverse momentum, and a factor

Nemanja Kaloper

We derive crystal braneworld solutions, comprising of intersecting families of parallel $n+2$-branes in a $4+n$-dimensional $AdS$ space. Each family consists of alternating positive and negative tension branes. In the simplest case of exactly orthogonal families, there arise different crystals with unbroken 4D Poincare invariance on the intersections, where

Elliot Leader, Dimiter B. Stamenov

We draw attention to some problems in the combined use of high-Q^2 deep inelastic scattering (DIS) data and low-Q^2 hyperon β-decay data in the determination of the polarized parton densities. We explain why factorization schemes like the JET or AB schemes are the simplest in which to study the implications of the DIS parton densities for the physics of the

Lars Bildsten, Robert E. Rutledge

Observations of soft X-ray transients (SXTs) in quiescence have found that the binaries harboring black holes are fainter than those that contain a neutron star. Narayan and collaborators postulated that the faint X-ray emission from black hole binaries was powered by an advection dominated accretion flow (ADAF). We explore an alternative explanation for the

G. Mao, S. Chiba, W. Greiner, K. Oyamatsu

We propose that spontaneous particle--anti-particle pair creations from the discharged vacuum caused by the strong interactions in dense matter are major sources of $γ$-ray bursts. Two neutron star collisions or black hole-neutron star mergers at cosmological distance could produce a compact object with its density exceeding the critical density for pair cre

Rita S. J. Kim, Michael A. Strauss, Neta A. Bahcall, James E. Gunn

The Sloan Digital Sky Survey has obtained 450 square degrees of photometric scan data, in five bands (u',g',r',i',z'), which we use to identify clusters of galaxies. We illustrate how we do star-galaxy separation, and present a simple and elegant method of detecting overdensities in the galaxy distribution, using the Voronoi Tessellation.

In-Saeng Suh, G. J. Mathews

Neutron stars with very strong surface magnetic fields have been suggested as the site for the origin of observed soft gamma repeaters (SGRs). In this paper we investigate the influence of such strong magnetic fields on the properties and internal structure of these magnetized neutron stars (magnetars). We study properties of a degenerate equilibrium ideal n

Yuri G. Prokhorov

The aim of these notes is to explain main ideas of the theory of complements. Basically we will follow Shokurov&#39;s work alg-geom/9711024.

Holger F. Hofmann, Takayoshi Kobayashi, Akira Furusawa

It is shown that the quantum jumps in the photon number n from zero to one or more photons induced by backaction evasion quantum nondemolition measurements of a quadrature component x of the vacuum light field state are strongly correlated with the quadrature component measurement results. This correlation corresponds to the operator expectation value <xnx>

Doug Singleton

The spin of a glueball is usually taken as coming from the spin (and possibly the orbital angular momentum) of its constituent gluons. In light of the difficulties in accounting for the spin of the proton from its constituent quarks, the spin of glueballs is reexamined. The starting point is the fundamental QCD field angular momentum operator written in term

Nuno Costa Dias

A general dynamical system composed by two coupled sectors is considered. The initial time configuration of one of these sectors is described by a set of classical data while the other is described by standard quantum data. These dynamical systems will be named half quantum. The aim of this paper is to derive the dynamical evolution of a general half quantum

Wynn C. G. Ho, Dong Lai

Recent work has shown that a young, rapidly rotating neutron star loses angular momentum to gravitational waves generated by unstable r-mode oscillations. We study the spin evolution of a young, magnetic neutron star including both the effects of gravitational radiation and magnetic braking (modeled as magnetic dipole radiation). Our phenomenological descrip

Andri M. Gretarsson, Sheila Rowan, Geppo Cagnoli, Gregory M. Harry

The use of fused-silica ribbons as suspensions in gravitational wave interferometers can result in significant improvements in pendulum mode thermal noise. Surface loss sets a lower bound to the level of noise achievable, at what level depends on the dissipation depth and other physical parameters. For LIGO II, the high breaking strength of pristine fused si