April 1997 arXiv papers — page 12

Feng Pan, J. P. Draayer

A general procedure for the derivation of SU(3)\supset U(2) reduced Wigner coefficients for the coupling (λ_{1}μ_{1})\times (λ_{2}μ_{2})\downarrow (λμ)^η, where ηis the outer multiplicity label needed in the decomposition, is proposed based on a recoupling approach according to the complementary group technique given in (I). It is proved that the non-multipl

Feng Pan, J. P. Draayer

A complementary group to SU(n) is found that realizes all features of the Littlewood rule for Kronecker products of SU(n) representations. This is accomplished by considering a state of SU(n) to be a special Gel'fand state of the complementary group {\cal U}(2n-2). The labels of {\cal U}(2n-2) can be used as the outer multiplicity labels needed to distin

Joseph Bernstein, Tanya Khovanova

We consider a special category of Hopf algebras, depending on parameters $Σ$ which possess properties similar to the category of representations of simple Lie group with highest weight $λ$. We connect quantum groups to minimal objects in this categories---they correspond to irreducible representations in the category of representations with highest weight $λ

M. I. Molina

The thermodynamics of an ideal gas enclosed in a box of volume a1 x a2 x a3 at temperature T is considered. The canonical partition function of the system is expressed in terms of complete elliptic integrals of the first kind, whose argument obeys a transcendental equation. For high and low temperatures we derive explicitly the main finite-volume corrections

W. D. Deering, M. I. Molina

We report on a theoretical and numerical investigation of the switching of power in new hybrid models of nonlinear coherent couplers consisting of optical slab waveguides with various orders of nonlinearity. The first model consists of two guides with second-order instead of the usual third-order susceptibilities as typified by the Jensen coupler. This secon

Herbert H. H. Homeier

Estimators $Πn$ for the correlation energy can be computed as roots of effective characteristic polynomials of degree $n$. The coefficients of these polynomials are derived from the terms of the perturbation series of the energy. From a fourth-order Møller-Plesset (MP4) calculation one can calculate with negligible effort a size-extensive estimator $Π2$ that

K. Amir-Azimi-Nili, J. M. Udias, H. Müther, L. D. Skouras

The reduced cross section for exclusive ($e,e'p$) reactions has been studied in DWIA for the example of the nucleus $^{16}$O using a spectral function containing effects of correlations. The spectral function is evaluated directly for the finite nucleus starting from a realistic nucleon-nucleon interaction within the framework of the Green's function

Paul H. Edelman, Jörg Rambau, Victor Reiner

There are two related poset structures, the higher Stasheff-Tamari orders, on the set of all triangulations of the cyclic $d$ polytope with $n$ vertices. In this paper it is shown that both of them have the homotopy type of a sphere of dimension $n-d-3$. Moreover, we resolve positively a new special case of the \emph{Generalized Baues Problem}: The Baues pos

I. P. Ennes, A. V. Ramallo

The fusion of Verma modules of the osp(1|2) current algebra is studied. In the framework of an isotopic formalism, the singular vector decoupling conditions are analyzed. The fusion rules corresponding to the admissible representations of the osp(1|2) algebra are determined. A relation between the characters of these last representations and those correspond

C. Adam

In this article we give a detailed discussion of the mass perturbation theory of the massive Schwinger model. After discussing some general features and briefly reviewing the exact solution of the massless case, we compute the vacuum energy density of the massive model and some related quantities. We derive the Feynman rules of mass perturbation theory and d

Changhyun Ahn, Kyungho Oh

We consider N=1 dualities in four dimensional supersymmetric gauge theories as a geometrical realization of wrapping D 6-branes around 3-cycles of Calabi-Yau threefolds in type IIA string theory. By extending the recent work of Ooguri and Vafa to the case of $SU, SO and Sp$ gauge groups with additional fields together with defining fields, we give simple geo

Atsushi Matsuo, Kiyokazu Nagatomo

We classify all the Heisenberg and conformal vectors and determine the full automorphism group of the free bosonic vertex algebra without gradation. To describe it we introduce a notion of inner automorphisms of a vertex algebra.

Igor Halperin

A complete set of asymptotic three particle light cone distribution amplitudes of twist 3 and 4 for a transversely polarized massive vector meson built out of massless current quarks is constructed. The method used is based on a modified conformal projectors technique which allows to handle kinematical corrections due to a finite hadron mass. Consequences of

Alan Kostelecky

This talk provides a short overview of recent results on possible CPT violation and some associated experimental signatures.

Z. Kunszt

I discuss recent developments in the theoretical study of Higgs search at LHC.

R. Baier, M. Dirks, K. Redlich, D. Schiff

In the framework of closed time path thermal field theory we investigate the production rate of hard thermal photons from a QCD plasma away from equilibrium. Dynamical screening provides a finite rate for chemically non-equilibrated distributions of quarks and gluons just as it does in the equilibrium situation. Pinch singularities are shown to be absent in

N. Fabiano

The possibility of formation for a bound state of a $t$ quark and a lighter one is investigated using potential model predictions and heavy quark effective theory approach. Resulting estimates for the 1S--2S splitting of the energy levels are compared to the total top decay width $Γ_t$ . As for the case of toponium, our conclusions show that the probability

E. Boos, A. Pukhov, M. Sachwitz, H. J. Schreiber

Results of complete tree level calculations of the single top production reaction $γe \to ν\bar{t} b$ at the Next Linear Collider, including the contribution of anomalous operators to the Wtb coupling are presented. The sensitivity for probing the structure of the Wtb coupling in a model independent way is analyzed and found to be significantly higher than f

C. Balazs, C. -P. Yuan

With a large integrated luminosity expected at the Tevatron, a next-to-leading order (NLO) calculation is no longer sufficient to describe the data which yield the precision measurement of $M_W$, etc. Thus, we extend the Collins-Soper-Sterman resummation formalism, for on-shell vector boson production, to correctly include the effects of the polarization and

D0 Collaboration

The gauge boson pair production processes Wg, WW, WZ, and Zg were studied using pbarp collisions corresponding to an integrated luminosity of ~14 pb-1 at a center-of-mass energy of sqrt(s) = 1.8 TeV. Analysis of Wg prod with subsequent W boson decay to lv (l=e,mu) is reported, including a fit to the pT spectrum of the photons which leads to limits on anomalo

M. Novello, V. A. De Lorenci

General relativity can be formulated either as in its original geometrical version (Einstein, 1915) or as a field theory (Feynman, 1962). In the Feynman presentation of Einstein theory an hypothesis concerning the interaction of gravity to gravity, which was hidden in the original version, becomes explicit. This is nothing but the assumed extension of the va

T. W. Baumgarte, G. B. Cook, M. A. Scheel, S. L. Shapiro

We perform fully relativistic calculations of binary neutron stars in quasi-equilibrium circular orbits. We integrate Einstein's equations together with the relativistic equation of hydrostatic equilibrium to solve the initial value problem for equal-mass binaries of arbitrary separation. We construct sequences of constant rest mass and identify the inne

Gabrielle Allen, Nils Andersson, Kostas D. Kokkotas, Bernard F. Schutz

We consider the perturbations of a relativistic star as an initial-value problem. Having discussed the formulation of the problem (the perturbation equations and the appropriate boundary conditions at the centre and the surface of the star) in detail we evolve the equations numerically from several different sets of initial data. In all the considered cases

L. Herrera, A. Di Prisco, J. L. Hernandez-Pastora, J. Martin

We analyse the effects of thermal conduction in a relativistic fluid, just after its departure from hydrostatic equilibrium, on a time scale of the order of thermal relaxation time. It is obtained that the resulting evolution will critically depend on a parameter defined in terms of thermodynamic variables, which is constrained by causality requirements.

Ichiro Oda

We study cosmic censorship in the Reissner-Nordstrom charged black hole by means of quantum gravity holding near the apparent horizons. We consider a gedanken experiment whether or not a black hole with the electric charge $Q$ less than the mass $M$ ($Q < M$) could increase its charge to go beyond the extremal limit $Q = M$ by absorbing the external charged

Patrick R. Brady, Scott A. Hughes

Recent numerical work by Wilson, Mathews, and Marronetti [J. R. Wilson, G. J. Mathews and P. Marronetti, Phys. Rev. D 54, 1317 (1996)] on the coalescence of massive binary neutron stars shows a striking instability as the stars come close together: Each star&#39;s central density increases by an amount proportional to 1/(orbital radius). This overwhelms any

Alan G. Wiseman

Recent numerical simulations of coalescing binary neutron stars conducted by Wilson, Mathews and Marronetti (WMM) show a rising central energy density of the stars as the orbital separation shrinks, i.e. the stars are individually crushed as they near coalescence. They claim this ``star-crushing&#39;&#39; effect is partially due to a non-linear, first post-N

D. Simonian, S. V. Kravchenko, M. P. Sarachik

The anomalous conducting phase that has been shown to exist in zero field in dilute two-dimensional electron systems in silicon MOSFETs is driven into a strongly insulating state by a magnetic field of about 20 kOe applied parallel to the plane. The data suggest that in the limit of T -> 0 the conducting phase is suppressed by an arbitrarily weak magnetic fi

E. Wasserman, J. R. Rustad, A. R. Felmy, B. P. Hay

We present a clear and rigorous derivation of the Ewald-like method for calculation of the electrostatic energy of the systems infinitely periodic in two-dimensions and of finite size in the third dimension (slabs) which is significantly faster than existing methods. Molecular dynamics simulations using the transferable/polarizable model by Rustad et al. wer

M. I. Molina, J. A Roessler, G. P. Tsironis

We perform a fully quantum mechanical numerical calculation for the problem of a single electron (or excitation) propagating in a N-site one-dimensional chain in the presence of a single Holstein impurity. We compute the long-time averaged probability for finding the electron on the impurity site as a function of the nonlinearity parameter, defined in terms

Frank Epperlein, Michael Schreiber, Thomas Vojta

We study the influence of electron-electron interactions on the electronic properties of disordered materials. In particular, we consider the insulating side of a metal-insulator transition where screening breaks down and the electron-electron interaction remains long-ranged. The investigations are based on the quantum Coulomb glass, a generalization of the

P. Sitko, K. -S. Yi, J. J. Quinn

A composite Fermion hierarchy theory is constructed in a way related to the original Haldane picture by applying the composite Fermion (CF) transformation to quasiparticles of Jain states. It is shown that the Jain theory coincides with the Haldane hierarchy theory for principal CF fillings. Within the Fermi liquid approach for few electron systems on the sp

Michel Pleimling, Walter Selke

Motivated by recent experiments on the metamagnet FeBr2, anomalies of the magnetization and the specific heat in the antiferromagnetic phase of related spin models are studied systematically using Monte Carlo simulations. In particular, the dependence of the anomalous behavior on competing intralayer interactions, the spin value and the Ising-like anisotropy

E. Orignac, T. Giamarchi

We study the effects of disorder on a system of two coupled chain of strongly correlated fermions (ladder system), using renormalization group. The stability of the phases of the pure system is investigated as a function of interactions both for fermions with spin and spinless fermions. For spinless fermions the repulsive side is strongly localized whereas t

S. R. Aladim, M. J. Martins

We construct a mixed spin 1/2 and $S$ integrable model and investigate its finite size properties. For a certain conformal invariant mixed spin system the central charge can be decomposed in terms of the conformal anomaly of two single integrable models of spin 1/2 and spin $(S-1/2)$. We also compute the ground state energy and the sound velocity in the ther

F. Rossi, G. Goldoni, E. Molinari

The scaling of exciton binding energy in semiconductor quantum wires is investigated theoretically through a non-variational, fully three-dimensional approach for a wide set of realistic state-of-the-art structures. We find that in the strong confinement limit the same potential-to-kinetic energy ratio holds for quite different wire cross-sections and compos

J. Theurer, P. Ulmschneider, W. Kalkofen

We study the evolution of spectra of acoustic waves that are generated in the convection zone and propagate upward into the photosphere, where we compare the simulated acoustic spectra with the spectrum observed in an Fe I line. Although there is no pronounced 3 min component in the spectra generated in the convection zone, there are dominant 3 min features

Francisco J. Jablonski, Marildo G. Pereira, Joao Braga, Clemens D. Gneiding

We report the detection of pulsations with $\sim 124$ s period in V2116 Oph, the optical counterpart of the low-mass X-ray binary GX 1+4. The pulsations are sinusoidal with modulation amplitude of up to 4% in blue light and were observed in ten different observing sessions during 1996 April-August using a CCD photometer at the 1.6-m and 0.6-m telescopes of L

L. Lemonon, M. Pierre, R. Hunstead, A. Reid

We present ROSAT PSPC and HRI observations of the distant cluster A1300 (z = 0.3071) in conjunction with optical data, to investigate the physics of the intra-cluster medium and the dynamical state of the cluster. By means of a multi-resolution wavelet analysis, we find evidence for structures in the X-ray emission of this very luminous (L_{X} ~ 1.7 10^{45}

P. A. Knight, T. J. Ponman

We report the results of 1-D hydrodynamical modelling of the evolution of gas in galaxy clusters. We have incorporated many of the effects missing from earlier 1-D treatments: improved modelling of the dark matter and galaxy distributions, cosmologically realistic evolution of the cluster potential, and the effects of a multiphase cooling flow. The model uti

Yi Hu, Wei-Ping Li

We give a method to construct stable vector bundles whose rank divides the degree over curves of genus bigger than one. The method complements the one given by Newstead. Finally, we make some systematic remarks and observations in connection with rationality of moduli spaces of stable vector bundles.

Henryk Fuks, Nino Boccara

We propose a probabilistic cellular automata model for the spread of innovations, rumors, news, etc. in a social system. The local rule used in the model is outertotalistic, and the range of interaction can vary. When the range R of the rule increases, the takeover time for innovation increases and converges toward its mean-field value, which is almost inver

N. Boccara, H. Fuks, Q. Zeng

Within the framework of a simple model of car traffic on a one-lane highway, we study the probability for car accidents to occur when drivers do not respect the safety distance between cars, and, as a result of the blockage during the time $T$ necessary to clear the road, we determine the number of stopped cars as a function of car density. We give a simple

A. Datta, Jin Min Yang, Bing-Lin Young, X. Zhang

We discuss single top quark production via u^i+\bar d^j \to t+\bar b at the Fermilab Tevatron in the minimal supersymmetric model with R-parity violation. We find that within the allowed range of coupling constants, the lepton-number violating couplings can give rise to observable effects when the slepton mass lies in a specific narrow range. For the baryon-

Raman Sundrum

Heavy Quark Effective Theory splits a heavy quark momentum into a large fixed momentum and a variable residual momentum, p = m_Q v + k. It thereby suffers a redundancy of description corresponding to small changes in the choice of the fixed velocity, v. The fact that full QCD is manifestly v-independent should lead to a non-trivial constraint on the form of

Marcelo Gleiser, Hans-Reinhard Müller

We investigate the matching between (1+1)-dimensional nonlinear field theories coupled to an external stochastic environment and their lattice simulations. In particular, we focus on how to obtain numerical results which are lattice-spacing independent, and on how to extract the correct effective potential which emerges from the simulations. As an applicatio

Don N. Page

At the minisuperspace level of homogeneous models, the bare probability for a classical universe has a huge peak at small universes for the Hartle-Hawking `no-boundary&#39; wavefunction, in contrast to the suppression at small universes for the `tunneling&#39; wavefunction. If the probability distribution is cut off at the Planck density (say), this suggests

L. Zielinski, K. Chaltikian, K. Birnbaum, C. M. Marcus

We investigate theoretically and experimentally classical advective transport in a 2D electron gas in a random magnetic field. For uniform external perpendicular magnetic fields large compared to the random field we observe a strong enhancement of conductance compared to the ordinary Drude value. This can be understood as resulting from advection of cyclotro

Lov K. Grover

Quantum mechanics permits certain kinds of non-local effects. This paper demonstrates how these can be used for distributed computation with minimal communication between various processors. The problem considered is that of estimating the mean of N items to a certain precision. First a serial quantum mechanical algorithm for this is presented that is faster

D. V. Ahluwalia

Review of the two volume set &#34;The Quantum Theory of Fields&#34; by S. Weinberg is presented.

R. G. Carlberg, H. K. C. Yee, H. Lin, C. W. Shepherd

Rich galaxy clusters are powerful probes of both cosmological and galaxy evolution parameters. The CNOC cluster survey was primarily designed to distinguish between Omega=1 and Omega~0.2 cosmologies. Projected foreground and background galaxies provide a field sample of comparable size. The results strongly support a low-density universe. The luminous cluste

Kyungsik Kang, Sin Kyu Kang

We discuss a new general class of mass matrix ansatz that respects the fermion mass hierarchy and calculability of the flavor mixing matrix. This is a generalization and justification of the various specific forms of the mass matrix by successive breaking of the maximal permutation symmetry. By confronting the experimental data, a large class of the mass mat

P. Magain, F. Courbin, S. Sohy

A new method for improving the resolution of astronomical images is presented. It is based on the principle that sampled data cannot be fully deconvolved without violating the sampling theorem. Thus, the sampled image should not be deconvolved by the total Point Spread Function, but by a narrower function chosen so that the resolution of the deconvolved imag

K. Kajantie, M. Karjalainen, M. Laine, J. Peisa

We study numerically the phase structure of the Ginzburg-Landau model, with particular emphasis on mass measurements. There is no local gauge invariant order parameter, but we find that there is a phase transition characterized by a vanishing photon mass. For type I superconductors the transition is of 1st order. For type II 1st order is excluded by suscepti

Bozhidar Z. Iliev

The general problem for consistency between arbitrary transports along paths in fibre bundles and bundle morphisms between them is formulated and investigated. The special case of one fibre bundle, its morphism and transport along paths acting in it is considered. The consistency between linear transports along paths in a vector bundle and a Hermitian struct

Bani Mitra Sodermark

The BRST structure of a current satisfying a non abelian affine algebra in two dimensions was studied by Isidro and Ramallo and an N=2 Superconformal Algebra was obtained. In this paper, we study the total BRST and anti BRST structure of the topological algebra. We end up with an N=4 Superconformal algebra in which the central charge drops out of most of the

S. M. Esakia, V. R. Garsevanishvili, T. R. Jalagania, G. O. Kuratashvili

Multiplicities of charged secondary hadrons in the relativistic nucleus-nucleus collisions in a wide energy range are analysed on the basis of partial stimul- ting emission and cluster cascading models. The experimental data are obtained by means of the two metre propane bubble chamber of JINR (Dubna). The results are compared with the correponding data for

G. V. Lipunova, V. M. Lipunov

The stages that follow the merging of two neutron stars are discussed. It is shown that if a rapidly rotating gravitationally bound object is formed after the merging (a spinar or a massive neutron star), then the characteristic time of its evolution is determined by a fundamental value t_{spin} = 3 k (m_p e^2 \hbar^{1/2}) / (m_e^3 c^{5/2} G^{1/2}) \approx 7

Tetsufumi Hirano, Shin Muroya, Mikio Namiki

We calculate the thermal photon distribution from the hot QCD matter produced by high energy nuclear collisions based on a hydrodynamical model, and compare it with the recent experimental data obtained by CERN WA80. Through the asymptotic value of the slope parameter of the transverse momentum distribution, we investigate the characteristic temperature of t

Akira Oguri

We study the relation between the dc conductance and the transmission through an interacting region based on the Kubo formalism using the perturbation analysis in the Coulomb interaction developed by Yamada-Yosida and Shiba. We find that the contributions of the vertex correction to the dc conductance disappear at T=0 if the currents are measured in the noni

Masakazu Murakami, Hidetoshi Fukuyama

The effects of Umklapp scattering on electronic states are studied in one spatial dimension at absolute zero. The model is basically the Hubbard model, where parameters characterizing the normal ($U$) and Umklapp ($V$) scattering are treated independently. The density of states is calculated in the t-matrix approximation by taking only the forward and Umklap

Seth Lloyd

This paper shows how the Greenberger-Horne-Zeilinger experiment, which demonstrates the nonlocal nature of quantum mechanics, can be performed using nuclear magnetic resonance on spins in molecules at finite temperature. The use of nuclear magnetic resonance techniques allows the experiment to uncover the nonlocality not just of special GHZ states, but of ar

Kazuyuki Fujii, Kunio Funahasi

We extend the Barut-Girardello coherent state for the representation of $SU(1,1)$ to the coherent state for a representation of $U(N,1)$ and construct the measure. We also construct a path integral formula for some Hamiltonian.

Francisco J. Herranz

A full (triangular) quantum deformation of so(3,2) is presented by considering this algebra as the conformal algebra of the 2+1 dimensional Minkowskian spacetime. Non-relativistic contractions are analysed and used to obtain quantum Hopf structures for the conformal algebras of the 2+1 Galilean and Carroll spacetimes. Relations between the latter and the nul

D. V. Ahluwalia

A consistent phenomenology of the interaction of particles of arbitrary spin requires covariant spinors, field operators, propagators and model interactions. Guided by an approach originally proposed by Weinberg, we construct from group theoretical arguments the (j,0)+(0,j) covariant spinors and the field operators for a massive particles. Specific examples

FOPI Collaboration

Semi-inclusive triple differential multiplicity distributions of positively charged kaons have been measured over a wide range in rapidity and transverse mass for central collisions of $^{58}$Ni with $^{58}$Ni nuclei. The transverse mass ($m_t$) spectra have been studied as a function of rapidity at a beam energy 1.93 AGeV. The $m_t$ distributions of K^+ mes

J. P. Wessels

In this talk some of the latest data on directed sideward, elliptic, radial, and longitudinal flow at AGS energies will be reviewed. A method to identify the reaction plane event by event and the measurement of its resolution will be discussed. The distributions of global observables (transverse energy E_T and charged particle multiplicity N_c), as well as t

Evgueni M. Semenov, Stephen J. Montgomery-Smith

Consider an n by n matrix x_ij, and consider the quantity || x_{i,pi(i)} ||_X where X is a symmetric sequence space as a random variable where the permutation pi is chosen randomly. This was considered by Kwapien and Schutt, and we extend their results to rearrangement invariant spaces. We also consider the property of D and D^* convexity for rearrangement i

Stephen J. Montgomery-Smith

Let $u(x,t)$ be the solution of the Schrödinger or wave equation with $L_2$ initial data. We provide counterexamples to plausible conjectures involving the decay in $t$ of the $\BMO$ norm of $u(t,\cdot)$. The proofs make use of random methods, in particular, Brownian motion. (Since this paper was written, the unsolved problem remaining in this paper has been

L. Grafakos, Stephen J. Montgomery-Smith, O. Motrunich

The best constant in the usual Lp norm inequality for the centered Hardy-Littlewood maximal function on R1 is obtained for the class of all ``peak-shaped&#39;&#39; functions. A positive function on the line is called ``peak-shaped&#39;&#39; if it is positive and convex except at one point. The techniques we use include convexity and an adaptation of the stan

Gary T. Horowitz, Simon F. Ross

It is shown that there are large static black holes for which all curvature invariants are small near the event horizon, yet any object which falls in experiences enormous tidal forces outside the horizon. These black holes are charged and near extremality, and exist in a wide class of theories including string theory. The implications for cosmic censorship

A. D. Jackson, M. K. Sener, J. J. M. Verbaarschot

We demonstrate the universality of the spectral correlation functions of a QCD inspired random matrix model that consists of a random part having the chiral structure of the QCD Dirac operator and a deterministic part which describes a schematic temperature dependence. We calculate the correlation functions analytically using the technique of Itzykson-Zuber

Thomas Guhr, Tilo Wettig

Using the graded eigenvalue method and a recently computed extension of the Itzykson-Zuber integral to complex matrices, we compute the $k$-point spectral correlation functions of the Dirac operator in a chiral random matrix model with a deterministic diagonal matrix added. We obtain results both on the scale of the mean level spacing and on the microscopic

Itzhak Bars

Extended superalgebras of types A,B,C, heterotic and type-I are all derived as solutions to a BPS equation in 14 dimensions with signature ( 11,3). The BPS equation as well as the solutions are covariant under SO( 11,3). This shows how supersymmetries with N<=8 in four dimensions have their origin in the same superalgebra in 14D. The solutions provide differ

H. Casini, R. Montemayor

Neutron stars are supposed to be mainly formed by a neutron superfluid. The angular momentum is given by the vortex array within the fluid, and a good account of the observable effects is determined by its coupling with the crust. In this article we show that the gravitational field introduces important modifications in the vortex distribution and shape. The

J. L. Petersen, J. Rasmussen, M. Yu

In this paper we consider Wakimoto free field realizations of simple affine Lie algebras, a subject already much studied. We present three new sets of results. (i) Based on quantizing differential operator realizations of the corresponding Lie algebras we provide general universal very simple expressions for all currents, more compact than has been establish

Ulf Lindström, Rikard von Unge

We use a phase space description to (re)derive a first order form of the Born-Infeld action for D-branes. This derivation also makes it possible to consider the limit where the tension of the D-brane goes to zero. We find that in this limit, which can be considered to be the strong coupling limit of the fundamental string theory, the world-volume of the D-br

Khaled Abdel-Khalek

We give a one dimensional octonionic representation of the different Clifford algebra Cliff(5,5)\sim Cliff(9,1), Cliff(6,6)\sim Cliff(10,2) and lastly Cliff(7,6)\sim Cliff(10,3) which can be given by (8x8) real matrices taking into account some suitable manipulation rules.

H. Jallouli, H. Sazdjian

The behavior of the two-particle Green&#39;s function in QED is analyzed in the limit when one of the particles becomes infinitely massive. It is found that the dependences of the Green&#39;s function on the relative times of the ingoing and outgoing particles factorize and that the bound state spectrum is the same as that of the Dirac equation with the stat

S. Kalyana Rama

We show that the evolution of the universe is singularity free in a class of graviton-dilaton models.

Friedemann Brandt

Using deformation theory based on BRST cohomology, a supergravity model is constructed which interpolates through a continuous deformation parameter between new minimal supergravity with an extra U(1) gauge multiplet and standard supergravity with local R-symmetry in a formulation with a nonstandard set of auxiliary fields. The deformation implements an elec

Burt A. Ovrut, Daniel Waldram

We discuss membranes in four-dimensional N=1 superspace. The kappa-invariance of the Green-Schwarz action implies that there is a dual version of N=1 supergravity with a three-form potential. We formulate this new supergravity in terms of a three-form superfield in curved superspace, giving the relevant constraints on the field strength. We find the correspo

B. G. Zakharov

The induced gluon radiation of a high energy quark in a finite-size QCD medium is studied. For a sufficiently energetic quark produced inside a medium we find the radiative energy loss $ΔE_{q}\propto L^{2}$, where L is the distance passed by quark in the medium. It has a weak dependence on the initial quark energy $E_{q}$. The $L^{2}$ dependence turns to $L^

D. Palle

We argue that the inclusion of the flavour-changing charged currents in the analysis of the Charm II data on neutrino- electron scattering could substantially change a fit of the effective couplings and makes impossible to draw any final conclusion on the Dirac or Majorana nature of neutrinos.

R. G. Badalian, S. Heppelmann

An analysis procedure is proposed to measure the antiquark distributions in the proton over the region 0.01 < x < 0.1. The procedure involves the measurement of high p_t asymmetric direct photon and jet final states in pp interactions. This measurement can be made at the RHIC collider running in pp mode at an energy of sqrt(s)=500 GeV/c. This analysis identi

Tamas S. Biro, Carsten Greiner

Utilizing the Langevin scenario for the linear sigma model we investigate the effect of friction and white noise on the evolution and stability of collective pionic fields in heavy ion collisions. We find that the smaller the volume the more stable pionic fluctuations become (the avergae mass increases). On the other hand the variance of the mass square incr

P. Colangelo, F. De Fazio, G. Nardulli, N. Paver

In the QCD Sum Rule determination of $m_s$ using the two-point correlator of divergences of $ΔS=1$ vector currents, the final uncertainty on $m_s$ is mainly due to the hadronic spectral function. Using a specific parameterization which fully takes into account the available experimental data on the $K π$ ($I=1/2, J^P=0^+)$ system, characterized by the presen

Alan R. White

When the Higgs sector of the standard model is replaced by a flavor doublet of color sextet quarks, dynamical electroweak symmetry breaking occurs, with the electroweak scale identified as the sextet chiral scale. Above the electroweak scale QCD is almost scale-invariant, leading to the high-momentum enhancement of both the sextet chiral condensate and insta

A. M. Badalian

The conventional parametrizations of lattice static interquark force are shown to produce a mismatch of coupling constant near the matching point R_m \approx 0.2 fm. The running coupling constant of the background perturbation theory yields instead a selfconsistent description of lattice data over all interval of distances, 0.05 fm \la R \la 1.1.fm, and is a

Victor Revoltovich Krym

Linear topological spaces with partial ordering (linear kinematics) are studied. They are defined by a set of 8 axioms implying that topology, linear structure and ordering are compatible with each other. Most of the results are valid for both the finite-dimensional and infinite-dimensional case. In applications to physics, partial ordering is interpreted as

Christos G. Tsagas, John D. Barrow

We provide a fully general-relativistic treatment of cosmological perturbations in a universe permeated by a large-scale primordial magnetic field, using the Ellis-Bruni gauge-invariant formalism. The exact non-linear equations for general relativistic magnetohydrodynamic evolution are derived. A number of applications are made: the behaviour of small pertur

Hing Tong Cho

We investigate the phenomenon of &#34;faster than light&#34; photons in a family of dilaton black hole spacetimes. For radially directed photons, we find that their light-cone condition is modified even though the spacetimes are spherically symmetric. They also satisfy the &#34;horizon theorem&#34; and the &#34;polarization sum rule&#34; of Shore. For orbita

N. I. Nessonov

This paper contains a complete description of classes of the unitary equivalence of the admissible representations of infinite-dimensional classic matrix groups paper.

James P. Sethna, Olga Perkovic, Karin A. Dahmen

Hysteresis, the lag between the force and the response, is often associated with noisy, jerky motion which have recently been called ``avalanches&#39;&#39;. The interesting question is why the avalanches come in such a variety of sizes: naively one would expect either all small events or one large one. Power-law distributions are often seen near transitions,

Swapan K. Pati, S. Ramasesha, Diptiman Sen

We use the density matrix renormalization group (DMRG) method to study the ground and low-lying excited states of three kinds of uniform and dimerized alternating spin chains. The DMRG procedure is also employed to obtain low-temperature thermodynamic properties of these systems. We consider a 2N site system with spins $s_1$ and $s_2$ alternating from site t

Ana Lopez, Eduardo Fradkin

We review the fermionic Chern-Simons field theory for the Fractional Quantum Hall Effect (FQHE). We show that in this field theoretic approach to the problem of interacting electrons moving in a plane in the presence of an external magnetic field, the FQHE states appear naturally as the semiclassical states of the theory. In this framework, the FQHE states a

A. C. Maggs

Actin is a filamentary protein which has many remarkable properties making it an ideal system for the study of the dynamics and mechanics of semi-flexible polymer solutions and gels; actin has a persistence length of over 10 microns and can polymerize to lengths of several tens of microns, this permits the use of video microscopy and other optical methods in

Angelo Cacciuto

We report a very detailed relation about the study, by a constrained Monte Carlo dynamic, of a 4D EA spin glass model (J=+/- 1). In particular we concentrate our attention on the behaviour of the system under different bounds imposed in order to optimize the dynamic and try to understand the low energy states structure. We find that in the thermodynamic limi

J. D. Lee, B. I. Min

Based on the Hamiltonian of small polarons with the strong nearest neighbor repulsion, we have investigated the charge ordering phenomena observed in half-doped manganites R_{1/2}A_{1/2}MnO_3. We have explored possible consequences of the charge ordering phase in the half-doped manganites. First, we have studied the renormalization of the sound velocity arou

J. D. Lee, B. I. Min

Based on the model combining the spin double exchange and the lattice polaron, we have studied the colossal magnetoresistance phenomena observed in perovskite manganites R_{1-x}A_xMnO_3. First, effects of both the double exchange and the electron-phonon interaction on the transport property are investigated. We have evaluated the temperature dependent resist