June 1999 arXiv papers — page 19

W. K. Baskerville

The finite energy vibrational normal modes of the baryon number B=7 Skyrme soliton are computed. The structure of the spectrum obtained displays considerable similarity to those previously calculated for baryon numbers 2, 3 and 4. All modes expected from an approximate correspondence between skyrmions and BPS monopoles are found to be present. However, in co

Christof Wetterich

The QCD-vacuum is characterized by the Higgs phenomenon for colored scalar fields. In this dual picture the gluons appear as the octet of vector mesons. Also quarks and baryons are identified. Gluon-meson and quark-baryon duality can account in a simple way for realistic masses of all low-mass hadrons and for their interactions.

U. Ellwanger

A field theoretic description of monopole condensation in strongly coupled gauge theories is given by actions involving antisymmetric tensors B_{μν} of rank 2. We rederive the corresponding action for 4d compact QED, summing explicitly over all possible monopole configurations. Its gauge symmetries and Ward identities are discussed. Then we consider the Wils

C. -W. H. Lee, S. G. Rajeev

This is a review article in which we will introduce, in a unifying fashion and with more intermediate steps in some difficult calculations, two infinite-dimensional Lie algebras of quantum matrix models, one for the open string sector and one for the closed string sector. Physical observables of quantum matrix models in the large-N limit can be expressed as

Brett McInnes

In discussions of the T-duality between the two heterotic string theories, the duality is actually implemented through the "common" SO(16) x SO(16) subgroup of "SO(32)" and E_8 x E_8. In fact, however, a global investigation shows that no such "common" subgroup exists. This paper is a survey of the relevant global properties of Spin(3

James N. Hormuzdiar, Stephen D. H. Hsu

We develop an algorithm which can be used to exclude the existence of classical breathers (periodic finite energy solutions) in scalar field theories, and apply it to several cases of interest. In particular, the technique is used to show that a pair of potentially periodic solutions of the 3+1 Sine-Gordon Lagrangian, found numerically in earlier work, are n

E. Katz, Y. Shadmi, Y. Shirman

The effects of heavy mass thresholds on anomaly-mediated soft supersymmetry breaking terms are discussed. While heavy thresholds completely decouple to lowest order in the supersymmetry breaking, it is argued that they do affect the breaking terms at higher orders. The relevant contributions typically occur at lower order in the loop expansion compared to pu

Fredrick I. Olness

We provide a brief overview of some current experimental and theoretical issues of heavy quark production.

B. I. Ermolaev, F. Olness, A. G. Shuvaev

We compute the deeply virtual Compton scattering (DVCS) amplitude for forward and backward scattering in the asymptotic limit. We make use of the Regge calculus to resum important logarithmic contributions that are beyond those included by the DGLAP evolution. We find a power-like behavior for the forward DVCS amplitude.

Cheuk-Yin Wong

The Color-Octet Model has been used successfully to analyze many problems in heavy quarkonium production. We examine some of the conceptual and practical problems of the soft gluon emission process in the Color-Octet Model. We use a potential model to describe the initial and final states in the soft gluon emission process, as the emission occurs at a late s

F. M. Al-Shamali, A. N. Kamal

Using NLL values for Wilson coefficients and including the contributions from the penguin diagrams, we estimate the amount of nonfactorization in two-body hadronic B decays. Also, we investigate the model dependence of the nonfactorization parameters by performing the calculation using different models for the form factors. The results support the universali

W. Vogelsang

We summarize the theory talks given in Working Group 4 `Polarized Lepton Nucleon Scattering' at the DIS 99 workshop. The significant progress made over the last year on many of the interesting topics in `spin physics' is documented.

A. N. Mitra

A qqq BSE formalism based on DBχS of an input 4-fermion Lagrangian of `current' u,d quarks interacting pairwise via gluon-exchange-propagator in its {\it non-perturbative} regime, is employed for the calculation of baryon self-energy via quark-loop integrals. To that end the baryon-qqq vertex function is derived under Covariant Instantaneity Ansatz (CIA)

F. Hautmann, Z. Kunszt, D. E. Soper

We describe diffractive deeply inelastic scattering in terms of diffractive parton distributions. We investigate these distributions in a hamiltonian formulation that emphasizes the spacetime picture of diffraction scattering. For hadronic systems with small transverse size, diffraction occurs predominantly at short distances and the diffractive parton distr

Gregory W. Carter, Dmitri Diakonov

The instanton approach to spontaneous chiral symmetry breaking is reviewed, with emphasis on the connection to chiral random matrix theory. We extend the approach to discuss the finite density, zero-temperature behaviour of quark matter. Since the instanton-induced interactions are attractive in both $\bar{q}q$ and $qq$ channels, a competition ensues between

M. -P. Lombardo

I discuss a few issues related with deconfinement at finite baryon density by considering lattice results for two colors QCD and ``toy'' studies of three colors QCD.

Hiroko Ichie, Hideo Suganuma

Based on the dual superconductor picture, we study the confinement phenomena systematically, using the lattice QCD, the monopole-current dynamics and the dual Ginzburg-Landau (DGL) theory. (1) We study the origin of abelian dominance for the confinement force in the maximally abelian (MA) gauge in terms of the gluon-field properties using the lattice QCD. In

Leonardo Fernandez-Jambrina

In this paper a theorem is derived in order to provide a wide sufficient condition for an orthogonally transitive cylindrical spacetime to be singularity-free. The applicability of the theorem is tested on examples provided by the literature that are known to have regular curvature invariants.

E. Nogueira, S. Coutinho, F. D. Nobre, E. M. F. Curado

The role of the distribution of coupling constants on the critical exponents of the short-range Ising spin-glass model is investigated via real space renormalization group. A saddle-point spin glass critical point characterized by a fixed-point distribution is found in an appropriated parameter space. The critical exponents $β$ and $ν$ are directly estimated

Guillaume Bal, Albert Fannjiang, George Papanicolaou, Leonid Ryzhik

We derive radiative transport equations for solutions of a Schrödinger equation in a periodic structure with small random inhomogeneities. We use systematically the Wigner transform and the Bloch wave expansion. The streaming part of the radiative transport equations is determined entirely by the Bloch spectrum, while the scattering part by the random fluctu

M. Peressi, M. Fornari, S. de Gironcoli, L. De Santis

We study by means of first-principles pseudopotential method the coordination defects in a-Si and a-Si:H, also in their formation and their evolution upon hydrogen interaction. An accurate analysis of the valence charge distribution and of the ``electron localization function'' (ELF) allows to resolve possible ambiguities in the bonding configuration

Vasili Perebeinos, Philip B. Allen

At 750K, LaMnO_3 has a cooperative Jahn-Teller (JT) distortion, with Mn atoms in distorted oxygen octahedra. This lifts the degeneracy of the singly-occupied $e_g$ orbitals of the Mn$^{3+}$ ions, which then become orbitally ordered. We use a minimal model to describe the ordered phase at T=0. The on-site Coulomb repulsion $U$ is set to infinity. There are tw

Dibyendu Das, Mustansir Barma

We study the effects of rapidly cooling to T = 0 a spin chain with conserved dynamics and competing interactions. Depending on the degree of competition, the system is found to get arrested in different kinds of metastable states. The most interesting of these has an inhomogeneous mixture of interspersed active and quiescent regions. In this state, the stead

Thorsten Geisinger, Marcus Mueller, Kurt Binder

We investigate the phase behavior of symmetric AB diblock copolymers confined into a thin film. The film boundaries are parallel, impenetrable and attract the A component of the diblock copolymer. Using a self-consistent field technique [M.W. Matsen, J.Chem.Phys. {\bf 106}, 7781 (1997)], we study the ordered phases as a function of incompatibility $χ$ and fi

F. D. A. Aarao Reis, S. L. A. de Queiroz, Raimundo R. dos Santos

We consider long, finite-width strips of Ising spins with randomly distributed couplings. Frustration is introduced by allowing both ferro- and antiferromagnetic interactions. Free energy and spin-spin correlation functions are calculated by transfer-matrix methods. Numerical derivatives and finite-size scaling concepts allow estimates of the usual critical

Thorsten Geisinger, Marcus Mueller, Kurt Binder

The structure of lamellar phases of symmetric $AB$ diblock copolymers in a thin film is investigated. We quantitatively compare the composition profiles and profiles of individual segments in self-consistent field calculations with Monte Carlo simulations in the bond fluctuation model for chain length N=32 and $χN=30$. Three film thicknesses are investigated

L. N. Bulaevskii, M. J. Graf, M. P. Maley

We consider the quasiparticle c-axis conductivity in highly anisotropic layered compounds in the presence of the magnetic field parallel to the layers. We show that at low temperatures the quasiparticle interlayer conductivity depends strongly on the orientation of the in-plane magnetic field if the excitation gap has nodes on the Fermi surface. Thus measure

Benjamin P. Lee, Jack F. Douglas, Sharon C. Glotzer

The influence of immobile filler particles (spheres, fibers, platelets) on polymer blend phase separation is investigated computationally using a generalization of the Cahn-Hilliard-Cook (CHC) model. Simulation shows that the selective affinity of one of the polymers for the filler surface leads to the development of concentration waves about the filler part

Ignacio Gomez, Indubala I. Satija

Within the framework of tight binding models, aperiodic systems are mapped to a renormalized lattice with a dimer defect. In models exhibiting metal-insulator transition, the dimer acts like a resonant cavity and explains the existence of the ballistic transport in the system. The localization in the model can be attributed to the vanishing of the coupling b

G. Seibold, F. Becca, F. Bucci, C. Castellani

The concept of frustrated phase separation is applied to investigate its consequences for the electronic structure of the high T_c cuprates. The resulting incommensurate charge density wave (CDW) scattering is most effective in creating local gaps in k-space when the scattering vector connects states with equal energy. Starting from an open Fermi surface we

Kazushige Machida, Tsutomu Nishira, Tetsuo Ohmi

The orbital symmetry of the superconducting order parameter in UPt_3 is identified by evaluating the directionally dependent thermalconductivity and ultrasound attenuation in the clean limit and compared with the existing data for both basal plane and the c-axis of a hexagonal crystal. The resulting two component orbital part expressed by (λ_x(k), λ_y(k)) is

Lev N. Shchur

The analysis of extensive numerical data for the percolation probabilities of incipient spanning clusters in two dimensional percolation at criticality are presented. We developed an effective code for the single-scan version of the Hoshen-Kopelman algorithm. We measured the probabilities on the square lattice forming samples of rectangular strips with width

Anders Johansen, Didier Sornette, Olivier Ledoit

We present a synthesis of all the available empirical evidence in the light of recent theoretical developments for the existence of characteristic log-periodic signatures of growing bubbles in a variety of markets including 8 unrelated crashes from 1929 to 1998 on stock markets as diverse as the US, Hong-Kong or the Russian market and on currencies. To our k

J. C. Boettger, M. D. Jones, R. C. Albers, D. J. Singh

The zero-presssure zero-temperature equilibrium volume and bulk modulus are calculated for fcc Th and Pu by two independent all-electron, full-potential, electronic-structure methods: the full-potential linear augmented-plane-wave (FLAPW) method and the linear combinations of Gaussian type orbitals-fitting function (LCGTO-FF) method. The results produced by

V. R. Manfredi, L. Salasnich

Nowadays there is no universally accepted definition of quantum chaos. In this paper we review and critically discuss different approaches to the subject, such as Quantum Chaology and the Random Matrix Theory. Then we analyze the problem of dynamical chaos and the time scales associated with chaos suppression in quantum mechanics. Summary: 1. Introduction 2.

R. Spurzem, A. Kugel

Astrophysical Challenges which demand the solution of the one million (or more) gravitating body problem are briefly discussed for the fields of cosmology, galactic nuclei and globular star clusters. Results from the classical three-body problem are to be combined with methods of statistical mechanics or thermodynamics in order to provide a reasonable model

R. Spurzem

Special high-accuracy direct force summation N-body algorithms and their relevance for the simulation of the dynamical evolution of star clusters and other gravitating N-body systems in astrophysics are presented, explained and compared with other methods. Other methods means here approximate physical models based on the Fokker-Planck equation as well as oth

T. Kuberka, A. Kugel, R. Maenner, H. Singpiel

In astrophysics numerical star cluster simulations and hydrodynamical methods like SPH require computational performance in the petaflop range. The GRAPE family of ASIC-based accelerators improves the cost-performance ratio compared to general purpose parallel computers, however with limited flexibility. The AHA-GRAPE architecture adds a reconfigurable FPGA-

E. Simonneau, F. Prada

By considering that the distribution of measured light along any galactocentric radius of an elliptical galaxy can be well represented by a R^{1/n} Sersic law, we propose in this paper a ``discrete ordenate'' method, which, for any value of n, allows an explicit expression for the luminous density, rho(r), to be found that can be numerically evaluate

Whipple Collaboration, A. C. Breslin, I. H. Bond, S. M. Bradbury

Markarian 501, a nearby (z=0.033) X-ray selected BL Lacertae object, is a well established source of Very High Energy (VHE, E>=300 GeV) gamma rays. Dramatic variability in its gamma-ray emission on time-scales from years to as short as two hours has been detected. Multiwavelength observations have also revealed evidence that the VHE gamma-ray and hard X-ray

M. Mouhcine, A. Lancon

A self-consistent spectrophotometric modelling of intermediate age post-starburst requires accurate stellar ingredients taking into account a principal feature of the stars dominating the near-IR emission during this phase: the variability of the AGB stars. A new library of stellar spectra based on averages of the empirical spectra of variable AGB stars is p

Donald M. Terndrup, Anita Krishnamurthi, Marc H. Pinsonneault, John R. Stauffer

We have photometrically monitored (Cousins Ic) eight low mass stars and brown dwarfs which are probable members of the Pleiades. We derived rotation periods for two of the stars - HHJ409 and CFHT-PL8 - to be 0.258 d and 0.401 d, respectively. The masses of these stars are near 0.4 and 0.08 Msun, respectively; the latter is the second such object near the hyd

M. Mouhcine, A. Lancon

We investigate techniques that can be used to determine ages of recently star forming regions during the phase dominated in the near-IR by the asymptotic giant branch stars (10^8-10^9 yrs). In particular, we present selected near-IR spectroscopic features that identify the contribution of O-rich and C-rich AGB variable stars to the integrated spectra of post

G. D. Banks, M. J. Disney, P. M. Knezek, H. Jerjen

We have commenced a 21-cm survey of the entire southern sky (δ< 0 degrees, -1200 km/s < v < 12700 km/s) which is &#39;&#39;blind&#39;&#39;, i.e. unbiased by previous optical information. In the present paper we report on the results of a pilot project which is based on data from this all-sky survey. The project was carried out on an area of 600 square degree

Gabriele Ghisellini, Annalisa Celotti

Quasi-thermal Comptonization is an attractive alternative to the synchrotron process to explain the spectra of GRBs, even if we maintain other important properties of the internal shock scenario, implying a compact emitting region and an equipartition magnetic field. Photon-photon absorption and electron-positron pairs can play a crucial role: this process m

Annalisa Celotti, Gabriele Ghisellini

Within the standard internal shock scenario, synchrotron emission would produce a spectrum with slope F(v) proportional to v^(-1/2), as immediate consequence of the cooling timescale being shorter than the integration time. This is in disagreement with the harder observed spectra, indicating that a different mechanism is responsible for the burst emission. F

Scott J. Kenyon, Jane X. Luu

We describe calculations of the evolution of an ensemble of small planetesimals in the outer solar system. In a solar nebula with a mass of several times the Minimum Mass Solar Nebula, objects with radii of 100-1000 km can form on timescales of 10-100 Myr. Model luminosity functions derived from these calculations agree with current observations of bodies be

A. Vazdekis, N. Arimoto

We derive new spectral H_gamma index definitions which are robust age indicators for old and relatively old stellar populations and thus have great potential for solving the age-metallicity degeneracy of galaxy spectra. To study H_gamma as a function of age, metallicity and resolution, we used a new spectral synthesis model which predicts SEDs of single-age,

P. M. Chadwick, K. Lyons, T. J. L. McComb, K. J. Orford

Atmospheric Cerenkov telescopes are used to detect electromagnetic showers from primary gamma rays of energy > 300 GeV and to discriminate these from cascades due to hadrons using the shape and orientation of the Cerenkov images. The geomagnetic field affects the development of showers and diffuses and distorts the images. When the component of the field nor

P. M. Chadwick, K. Lyons, T. J. L. McComb, K. J. Orford

A programme of detailed simulations of the response of the Durham Mark 6 atmospheric Cherenkov telescope is in progress. The effective collecting area for triggering by gamma-ray showers after application of selection criteria is derived as a function of energy. An initial result from the larger events in the 1996 and 1997 observations of the BL Lac PKS 2155

P. M. Chadwick, K. Lyons, T. J. L. McComb, K. J. Orford

Cen X-3 is a well-studied high-mass accreting X-ray binary and a variable source of high energy gamma rays from 100 MeV to 1 TeV. The object has been extensively monitored with the University of Durham Mark 6 telescope. Results of observations, including those taken in 1998 and 1999, are reported. There is no evidence for time variability in all the VHE data

P. M. Chadwick, K. Lyons, T. J. L. McComb, K. J. Orford

Observations have been made with the University of Durham Mark 6 telescope of a number of supernova remnants and young pulsars (Vela pulsar, PSR B1055-52, PSR J1105-6107, PSR J0537-6910 and PSR B0540-69). No VHE gamma ray emission, either steady or pulsed, has been detected from these objects.

Christopher L. Carilli, Karl M. Menten, Min Su Yun

We have detected redshifted CO (2-1) emission at 43 GHz and radio continuum emission at 1.47 and 4.86 GHz from the z = 4.4 QSO BRI 1335-0417 using the Very Large Array. The CO data imply optically thick emission from warm (>30 K) molecular gas with a total mass, M(H_2), of 1.5+/-0.3 x10^{11} M_solar, using the Galactic gas mass-to-CO luminosity conversion fa

P. M. Chadwick, K. Lyons, T. J. L. McComb, J. A. Murray

The University of Durham Mark 6 Telescope has been used to make observations of a number of AGNs visible from the Southern Hemisphere. Results are presented for limits to VHE gamma ray emission from 1ES 0323+022, PKS 0829+046, 1ES 1101-232, Cen A, PKS 1514-24, RXJ 10578-275 and 1ES 2316-423, both for steady emission and for outbursts on timescales of ~ 1 day

A. Mangalam, R. Nityananda, S. Sridhar

Violent relaxation during the collapse of a galaxy halo is known to be incomplete in realistic cases such as cosmological infall or mergers. We adopt a physical picture of strong but short lived interactions between potential fluctuations and particle orbits, using the broad framework outlined by Tremaine (1987) for incorporating incompleteness of the relaxa

P. M. Chadwick, K. Lyons, T. J. L. McComb, K. J. Orford

The X-ray selected BL Lac PKS 2155-304 has been observed using the University of Durham Mark 6 very high energy gamma ray telescope during 1998. We find no evidence for TeV emission during these recent observations when the X-ray flux was observed to be low. We have reconsidered our measurements made in 1997 November when PKS 2155-304 was in a bright X-ray s

K. Werner, S. Dreizler

We introduce the classical stellar atmosphere problem and describe in detail its numerical solution. The problem consists of the solution of the radiation transfer equations under the constraints of hydrostatic, radiative and statistical equilibrium (non-LTE). We outline the basic idea of the Accelerated Lambda Iteration (ALI) technique and statistical metho

J. Heidt, K. Nilsson, J. W. Fried, L. O. Takalo

We present subarcsecond resolution imaging and spectroscopy of the BL Lac object 1ES 1741+196 and neighboring galaxies. Based on 2-dimensional modelling, the host galaxy of 1ES 1741+196 is a very bright and large elliptical galaxy (M_R = -24.85, r_e = 51.2 kpc), whose overall luminosity distribution deviates significantly from a de Vaucouleurs profile. It is

N. Bhatt, N. K. Agarwal, C. K. Bhat, S. Bhattacharyya

The results of our observational campaigns on the two extragalactic sources Mkn 501 and Mkn 421, carried out with the Imaging Element of the TACTIC array, during March-May, 1998 and April-May, 1999, are presented. The results indicate that the two BL Lac objects (Mkn 501 and Mkn 421) were in a `low&#39; gamma-ray emission state during both epochs of our obse

K. Werner, B. Wolff

We performed a spectral analysis of the EUVE spectrum and ROSAT data of the unique object H1504+65, which is an extremely hot post-AGB star entering the white dwarf cooling sequence. It is the only pre-white dwarf known, whose surface is free of hydrogen and helium, hence, it represents the bare core of a former AGB star. The EUV spectrum (75--150A) is domin

E. E. Fenimore, E. Ramirez-Ruiz

We review the observational differences between gamma-ray bursts occurring on a single shell (such as in the external shock model) and multiple shells (such as in the internal shock model). We do not argue against external shocks or for internal shocks, as such, but rather against a single shell and for a central engine that is small enough to produce the ty

Y. -W. Lee, J. -H. Woo, S. Yi, J. -H. Park

The UV upturn phenomenon observed in elliptical galaxies is attractive for its potential value as an age indicator of old stellar systems. We present our most recent population models for the UV evolution of elliptical galaxies. We confirm that the dominant UV sources are either metal-poor or metal-rich hot horizontal-branch (HB) stars in local giant ellipti

W. Landsman

There is now considerable evidence that horizontal branch (HB) stars hotter than about 11,500 K experience an enormous enhancement of their photospheric iron abundance due to radiative levitation. In globular clusters, the photospheric iron abundance can reach values of [Fe/H] ~ +0.3, or up to two orders of magnitude higher than the cluster iron abundance. M

E. V. Gotthelf, G. Vasisht, T. Dotani

In previous papers, we presented the discovery of a 12-s X-ray pulsar in the supernova remnant Kes 73, providing the first direct evidence for an ultramagnetized neutron star, a magnetar, with an equivalent dipole field of nearly twenty times the quantum critical magnetic field. Our conclusions were based on two epochs of measurement of the spin, along with

Tapas K. Das

Though widely observed to be emanating out from a variety of galactic and extra-galactic sources, the underlying physical mechanism behind the formation of the cosmic jets and outflows are wrapped around by the veil of mystery till date. Neither the amount of matter contained in these jets could accurately be calculated by any definitive method. In this pape

Jeremy Michelson, Marcus Spradlin

The Kaluza-Klein spectrum of N=2, D=4 supergravity compactified on AdS_2 x S^2 is found and shown to consist of two infinite towers of SU(1,1|2) representations. In addition to `pure gauge' modes living on the boundary of AdS which are familiar from higher dimensional cases, in two dimensions there are modes (e.g. massive gravitons) which enjoy no gauge symm

Matthias W. Reinsch, James J. Morehead

Asymptotic expressions for Clebsch-Gordan coefficients are derived from an exact integral representation. Both the classically allowed and forbidden regions are analyzed. Higher-order approximations are calculated. These give, for example, six digit accuracy when the quantum numbers are in the hundreds.

O. Bergman, M. R. Gaberdiel

It is conjectured that the two closed bosonic string theories, Type 0A and Type 0B, correspond to certain supersymmetry breaking orbifold compactifications of M-theory. Various implications of this conjecture are discussed, in particular the behaviour of the tachyon at strong coupling and the existence of non-perturbative fermionic states in Type 0A. The lat

Matthias Vojta, R. E. Hetzel, R. M. Noack

We investigate the charge-order transition at zero temperature in a two-leg Hubbard ladder with additional nearest-neighbor Coulomb repulsion V using the Density Matrix Renormalization Group technique. We consider electron densities between quarter and half filling. For quarter filling and U=8t, we find evidence for a continuous phase transition between a ho

J. Xu, R. L. B. Selinger, J. V. Selinger, B. R. Ratna

Using Monte Carlo simulation methods, we explore the role of molecular shape in the phase behavior of liquid crystals and the electroclinic effect. We study a &#34;bent-rod&#34; mesogen shaped like the letter Z, composed of seven soft spheres bonded rigidly together with no intra-molecular degrees of freedom. For strongly angled molecules, we find that steri

H. Dehmelt, R. Mittleman, R. S. Van Dyck,, P. Schwinberg

In our past experiments on a single electron and positron we measured the cyclotron and spin-cyclotron difference frequencies omega_c and omega_a and the ratios a = omega_a/ omega_c at omega_c = 141 Ghz for e^- and e^+ and later, only for e^-, also at 164 Ghz. Here, we do extract from these data, as had not done before, a new and very different figure of mer

Jaume Guasch, Joan Sola

We study the FCNC top quark decays t -> c h in the framework of the MSSM, where h= h^0,H^0,A^0 is any of the supersymmetric neutral Higgs bosons. We include the leading set of SUSY-QCD and SUSY electroweak contributions. While the FCNC top quark decay into the SM Higgs boson has such a negligible rate that will not be accessible to any presently conceivable

Paul Mansfield, David Nolland

We compute the conformal anomalies of boundary CFTs for scalar and fermionic fields propagating in AdS spacetime at one-loop. The coefficients are quantized, with values related to the mass-spectra for Kaluza-Klein compactifications of Supergravity on AdS5xS5 and AdS7xS4. Our approach interprets the boundary partition function of fields propagating on AdS sp

P. Nadolsky, D. R. Stump, C. -P. Yuan

We present a formalism that improves the applicability of perturbative QCD in the current region of semi-inclusive deep inelastic scattering. The formalism is based on all-order resummation of large logarithms arising in the perturbative treatment of hadron multiplicities and energy flows in this region. It is shown that the current region of semi-inclusive

S. Anantha Ramakrishna, N. Kumar

We show that the delay time distribution for wave reflection from a one-dimensional random potential is related directly to that of the reflection coefficient, derived with an arbitrarily small but uniform imaginary part added to the random potential. Physically, the reflection coefficient, being exponential in the time dwelt in the presence of the imaginary

C. J. van der Beek, M. Konczykowski, R. J. Drost, P. H. Kes

Dynamic and thermodynamic magnetization experiments on heavy-ion irradiated single crystalline Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} are correlated in order to clarify the nature of the mixed state phase diagram. It is shown that whereas the entropy contribution to the free energy in the London regime plays a minor role in unirradiated crystals and irradiated crystals

A. N. Kvinikhidze, B. Blankleider

We show how to derive the complete set of electromagnetic corrections to the Nambu-Jona-Lasinio (NJL) model of the nucleon. Our results enable an accurate estimate of the electromagnetic contribution to the neutron-proton mass difference within this model. At the same time, our procedure demonstrates the way to calculate the complete set of meson corrections

M. Kastner, J. D. Munoz, M. Promberger

A method is presented which allows for a tremendous speed-up of computer simulations of statistical systems by orders of magnitude. This speed-up is achieved by means of a new observable, while the algorithm of the simulation remains unchanged.

Asher Peres

The measuring process is an external intervention in the dynamics of a quantum system. It involves a unitary interaction of that system with a measuring apparatus, a further interaction of both with an unknown environment causing decoherence, and then the deletion of a subsystem. This description of the measuring process is a substantial generalization of cu

B. I. Ermolaev, M. Greco, S. I. Troyan

A generalization of the leading-order DGLAP evolution at small x is performed for the non-singlet structure function by resumming the leading-order DGLAP anomalous dimension to all orders in the QCD coupling. Explicit expressions are obtained for the non-singlet structure function of the deep inelastic scattering, taking into account both the double-logarith

Lucian M. Ionescu

Ideals are used to define homological functors for additive categories. In abelian categories the ideals corresponding to the usual universal objects are principal, and the construction reduces, in a choice dependent way, to homology groups. Applications are considered: derived categories and functors.

C. Giunti

Considering the scheme with mixing of three neutrinos and a mass hierarchy that can accommodate the results of solar and atmospheric neutrino experiments, it is shown that the results of solar neutrino experiments imply a lower bound for the effective Majorana mass in neutrinoless double-beta decay, under the natural assumptions that massive neutrinos are Ma

The E877 Collaboration, J. Barrette

Inclusive double differential multiplicities of deuterons, ^3H, ^3He, and ^4He measured by E877 for 11.5 A GeV/c Au+Au collisions at the AGS are presented. Light fragments at beam-rapidity are measured for the first time at AGS energies. Beam rapidity deuteron and ^4He yields and transverse slope parameters are found to be strongly dependent on impact parame

Z. G. Dai, T. Lu

In a recent paper (Dai & Lu 1999), we have proposed a simple model in which the steepening in the light curve of the R-band afterglow of the gamma-ray burst (GRB) 990123 is caused by the adiabatic shock which has evolved from an ultrarelativistic phase to a nonrelativistic phase in a dense medium. We find that such a model is quite consistent with observatio

Robert Fleischer, Joaquim Matias

We present allowed regions in the space of observables of certain non-leptonic B-meson decays that characterize these modes within the Standard Model. A future measurement of observables lying significantly outside of these regions would indicate the presence of new physics. Making use of SU(3) arguments, we give the range for $B\toπK$ decays, and for the sy

S. -K. Yip

The internal vortex structure of a trapped spin-1 Bose-Einstein condensate is investigated. It is shown that it has a variety of configurations depending on, in particular, the ratio of the relevant scattering lengths and the total magnetization.

Parthasarathi Majumdar, Soumitra SenGupta

A manifestly gauge invariant formulation of the coupling of the Maxwell theory with an Einstein Cartan geometry is given, where the space time torsion originates from a massless Kalb-Ramond field augmented by suitable U(1) Chern Simons terms.We focus on the situation where the torsion violates parity, and relate it to earlier proposals for gravitational pari

K. G. Chetyrkin, R. Harlander, T. Seidensticker, M. Steinhauser

Corrections of $O(α_s^2)$ to the decay of the top quark into a W boson and a bottom quark are calculated. The method is based on an expansion of the top quark propagator for small external momentum, q, as compared to the top quark mass, M_t. The physical point q^2 = M_t^2 is reached through Padé approximations. The described method allows to take effects ind

A. Różańska B. Czerny

We determine simple analytical conditions for combined radiative and thermal equilibrium between the X-ray emitting plasma and cold reprocessor in active galactic nuclei (AGN) and galactic black holes (GBH). These conditions determine the pressure at the transition zone, which is not arbitrary in the static situation. The conditions for static solution are d

M. Yu. Zotov

Local solutions of the static, spherically symmetric Einstein-Yang-Mills (EYM) equations with SU(2) gauge group are studied on the basis of dynamical systems methods. This approach enables us to classify EYM solutions in the origin neighborhood, to prove the existence of solutions with the oscillating metric as well as the existence of local solutions for al

H. P. Breuer, B. Kappler, F. Petruccione

A generalization of the stochastic wave function method to quantum master equations which are not in Lindblad form is developed. The proposed stochastic unravelling is based on a description of the reduced system in a doubled Hilbert space and it is shown, that this method is capable of simulating quantum master equations with negative transition rates. Non-

T K Rai Dastidar

A non-local gauge symmetry of a complex scalar field, which can be trivially extended to spinor fields, was demonstrated in a recent paper (Mod.Phys.Lett. A13, 1265 (1998) ; hep-th/9902020). The corresponding covariant Lagrangian density yielded a new, non-local Quantum Electrodynamics. In this letter we show that as a consequence of this new QED, a blackbod

Amita Das, P. H. Diamond

The theory of mean field electrodynamics for diffusive processes in Electron Magnetohydrodynamic (EMHD) model is presented. In contrast to Magnetohydrodynamics (MHD) the evolution of magnetic field here is governed by a nonlinear equation in the magnetic field variables. A detailed description of diffusive processes in two dimensions are presented in this pa

Christopher Gordon

The problem of modeling forest tree growth curves with an artificial neural network (NN) is examined. The NN parametric form is shown to be a suitable model if each forest tree plot is assumed to consist of several differently growing sub-plots. The predictive Bayesian approach is used in estimating the NN output. Data from the correlated curve trend (CCT) e

W. Ebeling, J. Ortner

A survey on the dynamical and thermodynamical properties of plasmas with strong Coulomb interactions in the quasi-classical density-temperature region is given. First the basic theoretical concepts describing nonideality are discussed. The chemical picture is introduced. It is shown that the nonideal plasma subsystem of the free charges has a rather large qu

Blas Echebarria, Hermann Riecke

Three coupled Ginzburg-Landau equations for hexagonal patterns with broken chiral symmetry are investigated. They are relevant for the dynamics close to onset of rotating non-Boussinesq or surface-tension-driven convection. Steady and oscillatory, long- and short-wave instabilities of the hexagons are found. For the long-wave behavior coupled phase equations

A. Ramos, E. Oset

The self-energy of the K^- meson in nuclear matter is calculated in a self-consistent microscopic approach, using a \bar{K}N interaction obtained from the lowest-order meson-baryon chiral Lagrangian. The effective \bar{K}N interaction in the medium is derived by solving the coupled-channel Bethe-Salpeter equation including Pauli blocking on the nucleons, mea

V. D. Efros

The method of integral transforms is reviewed. In the framework of this method reaction observables are obtained with the bound--state calculation techniques. New developments are reported.

NA44 Collaboration, H. Boggild et al

Correlations of two protons emitted near midrapidity in p+Pb collisions at 450 GeV/c and S+Pb collisions at 200A GeV/c are presented, as measured by the NA44 Experiment. The correlation effect, which arises as a result of final state interactions and Fermi-Dirac statistics, is related to the space-time characteristics of proton emission. The measured source

M. D&#39;Agostino, F. Gulminelli, Ph. Chomaz, M. Bruno

An experimental indication of negative heat capacity in excited nuclear systems is inferred from the event by event study of energy fluctuations in $Au$ quasi-projectile sources formed in $Au+Au$ collisions at 35 A.MeV. The excited source configuration is reconstructed through a calorimetric analysis of its de-excitation products. Fragment partitions show si