February 1997 arXiv papers — page 12

J. C. Anjos, G. Herrera, J. Magnin, F. R. A. Simao

We propose a two-component model involving the parton fusion mechanism and recombination of a $ud$ valence diquark with a sea $c$-quark of the incident proton to describe $Λ_c^+$ inclusive production in $pp$ collisions. We also study the polarization of the produced $Λ_c^+$ in the framework of the Thomas Precession Model for polarization. We show that a meas

Arttu Rajantie

A three-dimensional effective theory of the finite-temperature SU(5)+adjoint Higgs model is constructed using the method of dimensional reduction. The resulting theory can be used for computer simulations of the GUT phase transition of the early universe. In this paper the transition is analyzed at two-loop level in perturbation theory. The structure of the

Jan von Delft, A. W. W. Ludwig, Vinay Ambegaokar

Recent experiments by Ralph and Buhrman on zero-bias anomalies in quenched Cu nanoconstrictions (reviewed in the preceding paper, I), are in accord with the assumption that the interaction between electrons and nearly degenerate two-level systems in the constriction can be described, for sufficiently small voltages and temperatures ($V,T < \Tk$), by the 2-ch

Jan von Delft, D. C. Ralph, R. A. Buhrman, S. K. Upadhyay

Certain zero-bias anomalies (ZBAs) in the voltage, temperature and magnetic field dependence of the conductance $G(V,T,H)$ of quenched Cu point contacts have previously been interpreted to be due to non-magnetic 2-channel Kondo (2CK) scattering from near-degenerate atomic two-level tunneling systems (Ralph and Buhrman, 1992; Ralph et al. 1994), and hence to

J. Ranninger, J. M. Robin

The question of whether the pseudogap in high $T_c$ cuprates is related to super conducting precursor effects or to the existence of extrinsic bosonic massive excitations is investigated on the basis of the Boson-Fermion model. The characteristic three peak structure of the electronic spectral function and the temperature dependent Fermi vector derived here

S. Alam, C. Bentley

The m-photon Jaynes-Cummings Hamiltonian is a natural generalization of the much studied Jaynes-Cummings Hamiltonian. In this short note we give the relevant operators for the time-dependent generalized m-photon Jaynes-Cummings Hamiltonian. The dynamical equations for these operators are also given. These operators are needed and indeed are the basic buildin

Ami Glasner, Eli Livne, Baruch Meerson

We show that any generic non-adiabatic slow flow of ideal compressible fluid develops a significant vorticity. As an example, an initially irrotational conductive cooling flow is considered. A perturbation theory for the vorticity generation is developed that employs, as a zero order solution, a novel two-dimensional similarity solution. Full gasdynamic simu

K. Kar, S. Sarkar, J. M. G. Gomez, V. R. Manfredi

The structure of nuclei in the lower half of fp shell is investigated by the spectral distribution method using the modified Kuo-Brown interaction. This interaction recently showed success in reproducing observed properties through detailed shell model studies. Spectral distribution studies avoid explicit diagonalization and hold promise for applications to

David G. Wagner

We consider a specialization $Y_M(q,t)$ of the Tutte polynomial of a matroid $M$ which is inspired by analogy with the Potts model from statistical mechanics. The only information lost in this specialization is the number of loops of $M$. We show that the coefficients of $Y_M(1-p,t)$ are very simply related to the ranks of the Whitney homology groups of the

Joram Lindenstrauss

This is a survey of the area mentioned in the title.

S. W. Hawking, M. M. Taylor-Robinson

Near extreme black holes can lose their charge and decay by the emission of massive BPS charged particles. We calculate the greybody factors for low energy charged and neutral scalar emission from four and five dimensional near extremal Reissner-Nordstrom black holes. We use the corresponding emission rates to obtain ratios of the rates of loss of excess ene

Bjørn Jensen, Parviz H. Mani

The question of the stability of the four dimensional Gross-Perry-Sorkin Kaluza-Klein magnetic monopole solution is investigated within the framework of a N=2, D=5 supergravity theory. We show that this solution does not support a spin structure of the Killing type and is therefore, contrary to previous expectations, not necessarily stable.

Ram Brustein, Richard Madden

String cosmology solutions are examined in a generalized phase-space including sources representing arbitrary corrections to lowest order string-dilaton-gravity effective action. We find a set of necessary conditions for a graceful exit transition from a dilaton-driven inflationary phase to a radiation dominated era. We show that sources allowing such a tran

Marc Henneaux, Bernard Knaepen, Christiane Schomblond

We completely compute the local BRST cohomology $H(s|d)$ of the combined Yang-Mills-2-form system coupled through the Yang-Mills Chern-Simons term (&#34;Chapline-Manton model&#34;). We consider the case of a simple gauge group and explicitely include in the analysis the sources for the BRST variations of the fields (&#34;antifields&#34;). We show that there

Indranil Dasgupta

We consider vacuum tunneling of a new kind where the false vacua are not translationally invariant, but have topological defects that break some of their translational symmetries. In the particular case where the topological defects are cosmic strings, we show the existence of an O(2) \times O(2) symmetric bounce configuration that allows a semi-classical es

Charles Gale, David Seibert, Joseph Kapusta

We compute the mass shifts and mixing of the Omega and Phi mesons at finite temperature due to scattering from thermal pions. The Rho and b_1 mesons are important intermediate states. Up to a temperature of 140 MeV the Omega mass increases by 12 MeV and the Phi mass decreases by 0.6 MeV. The change in mixing angles is negligible.

Silas R. Beane

Phenomenologically motivated Lie-algebraic sum rules determine the representations of unbroken SU(2)_L X SU(2)_R filled out by mesons containing a single heavy quark, in the limit that the heavy quark mass goes to infinity. This representation content determines the strong single-pion transition amplitudes of all heavy meson states in the chiral limit. Predi

Sarira Sahu

The active-sterile neutrino conversion probability is calculated for neutrino propagating in a medium in the presence of random magnetic field fluctuations. Necessary condition for the probability to be positive definite is obtained. Using this necessary condition we put constraint on the neutrino magnetic moment from active-sterile electron neutrino convers

Boris Kayser

Although CP violation was discovered more than thirty years ago, its origin is still unknown. In these lectures, we describe the CP-violating effects which have been seen in K decays, and explain how CP violation can be caused by the Standard Model weak interaction. The hypothesis that this interaction is indeed the origin of CP violation will be incisively

T. Gehrmann

In this paper we calculate the O($α_s$) corrections to the $x_F$- and $y$-distributions of lepton pairs produced in collisions of longitudinally polarized hadrons. The numerical importance of these corrections is studied and consequences for the extraction of the polarized sea quark distributions from a measurement of the longitudinally polarized Drell-Yan c

E. H. Simmons

We review the connection between m_t and the $Zb\bar b$ vertex in ETC models and discuss how data on R_b constrains ETC models. Theories in which the ETC and weak gauge groups do not commute are consistent with electroweak data and predict effects on single top production that will be visible at Fermilab.

Wei-Shu Hou, Guey-Lin Lin, Chien-Yi Ma, C. -P. Yuan

Uniquely heavy with mass at the weak scale, the top quark may have large flavor changing couplings to Higgs bosons that are as yet unexplored. We show that such couplings can be directly probed at the LHC through the parton subprocess $c(\bar c)g \to t (\bar t)A^0$, where the pseudoscalar $A^0$ subsequently decays into $t \bar c$ or ${\bar t} c$, giving rise

C. Tix

A lower bound for the ground state energy of a one particle relativistic Hamiltonian - sometimes called no-pair operator - is provided.

G. Herrera, J. Magnin, Luis M. Montaño, F. R. A. Simão

We use the recombination and the Thomas Precession Model to obtain a prediction for the $Λ_0$ polarization in the $p+p \to Λ_0+X$ reaction. We study the effect of the recombination function on the $Λ_0$ polarization.

J. dos Anjos, G. Herrera, J. Magnin, F. R. A. Simão

We propose a two component model for charmed baryon production in $pp$ collisions consisting of the conventional parton fusion mechanism and fragmentation plus quarks recombination in which a $ud$ valence diquark from the proton recombines with a $c$-sea quark to produce a $Λ_c^+$. Our two-component model is compared with the intrinsic charm two-component mo

J. Rodríguez-Quintero, O. Pène, M. Lozano

We study the high energy behaviour of fermions hitting a general wall caused by a first-order phase transition. The wall profile is introduced through general analytic and non-analytic functions. The reflection coefficient is computed in the high energy limit and its connection with the analytic properties of the wall profile function is shown. The high ener

Simon Hands

I review three different non-perturbative approaches to the three dimensional Thirring model: the 1/N_f expansion, Schwinger-Dyson equations, and Monte Carlo simulation. Simulation results are presented to support the existence of a non-perturbative fixed point at a chiral symmetry breaking phase transition for N_f=2 and 4, but not for N_f=6. Spectrum calcul

Jennie Traschen, K. Z. Win

We present analytical perturbative, and numerical solutions of the Einstein equation which describe a black hole with a nontrivial dilaton field and a purely topological gauge potential. The gauge potential has zero field strength and hence no stress-energy, but it does couple to virtual string worldsheets which wrap around the Euclidean horizon two-sphere,

Yuri N. Obukhov, Eckehard W. Mielke, Jan Budczies, Friedrich W. Hehl

The translational Chern-Simons type three-form coframe torsion on a Riemann-Cartan spacetime is related (by differentiation) to the Nieh-Yan four-form. Following Chandia and Zanelli, two spaces with non-trivial translational Chern-Simons forms are discussed. We then demonstrate, firstly within the classical Einstein-Cartan-Dirac theory and secondly in the qu

Jorge Pullin

Contents: News: April 1997 Joint APS/AAPT Meeting, by Beverly Berger TGG News, by Jim Isenberg Report from NSF, by David Berley We hear that..., by Jorge Pullin Research briefs: GR in GPS, by Neil Ashby What happens near the innermost stable circular orbit? by Doug Eardley Conference reports: Journees Relativistes 96, by D. Brill, M. Heusler, G. Lavrelashvil

Carlos O. Lousto

I present here the results of the study of the gravitational radiation generated by the infall (from rest at radius $r_0$) of a point particle of mass $m_0$ into a Schwarzschild black hole of mass $M$. We use Laplace&#39;s transform methods and find that the spectra of radiation for $\sim5M<r_0<\infty$ presents a series of evenly spaced bumps. The total radi

Maurice H. P. M. van Putten

The Riemann-Lebesque Theorem is commonly proved in a few strokes using the theory of Lebesque integration. Here, the upper bound $2π|c_k(f)|\le S_k(f)-s_k(f)$ for the Fourier coefficients $c_k$ is proved in terms of majoring and minoring Riemann sums $S_k(f)$ and $s_f(k)$, respectively, for Riemann integrable functions $f(x)$. This proof has been used in a c

Oron Zachar, S. A. Kivelson, V. J. Emery

We consider a Landau theory of coupled charge and spin-density wave order parameters as a simple model for the ordering that has been observed experimentally in the La_2NiO_4 and La_2CuO_4 families of doped antiferromagnets. The period of the charge-density wave is generically half that of the spin-density wave, or equivalently the charges form antiphase dom

Joachim Stelzer, Henryk Arodz

Analytical calculations of the dynamics of a curved domain wall in a nematic liquid crystal are performed. The core of the wall is assumed to form a cylinder, whose axis coincides with the direction of an external magnetic field. The equation of motion for the nematic director field is solved in a comoving coordinate frame by applying a polynomial expansion

L. Wendler, T. Kraft, M. Hartung, A. Berger

Grating-coupler-induced collective intersubband transitions in a quasi-two-dimensional electron system are investigated both experimentally and theoretically. Far-infrared transmission experiments are performed on samples containing a quasi-two-dimensional electron gas quantum-confined in a parabolic quantum well. For rectangular shaped grating couplers of d

J. Loos, H. Fehske

Inspired by recent experiments on the Sr-doped nickelates, $La_{2-x}Sr_xNiO_4$, we propose a minimal microscopic model capable to describe the variety of the observed quasi-static charge/lattice modulations and the resulting magnetic and electronic-transport anomalies. Analyzing the motion of low-spin (s=1/2) holes in a high-spin (S=1) background as well as

C. Ratsch, P. Ruggerone, M. Scheffler

This paper gives a summary of basic concepts of density-functional theory (DFT) and its use in state-of-the-art computations of complex processes in condensed matter physics and materials science. In particular we discuss how microscopic growth parameters can be determined by DFT and how on this basis macroscopic phenomena can be described. To reach the time

Ya. M. Blanter, M. Buttiker

We investigate the correlations in the current fluctuations at different terminals of metallic diffusive conductors. We start from scattering matrix expressions for the shot noise and use the Fisher-Lee relation in combination with diagram technique to evaluate the noise correlations. Of particular interest are exchange (interference) effects analogous to th

Nobuo Suzuki, Fumitaka Matsubara

We study the S=1/2 quantum antiferromagnetic XY model on finite triangular lattices with N sites in both longitudinal and transverse magnetic fields. We calculate physical quantities in the ground state using a diagonalization for spins $N \leq 27$, and those at finite temperatures using a quantum transfer Monte Carlo method for $N \leq 24$. In the longitudi

P. Schwab, U. Eckern

We calculate the average persistent current in a normal conducting, mesoscopic ring in the diffusive regime. In the presence of magnetic impurities, a contribution to the persistent current is identified, which is related to fluctuations in the electron spin density. Assuming a spin-flip scattering rate which is comparable to the Thouless energy E_c and low

M. V. Ganduglia-Pirovano, J. Kudrnovsky, M. Scheffler

We calculate the difference of the ionization energies of a core-electron of a surface alloy, i.e., a B-atom in a A_(1-x) B_x overlayer on a fcc-B(001)-substrate, and a core-electron of the clean fcc-B(001) surface using density-functional-theory. We analyze the initial-state contributions and the screening effects induced by the core hole, and study the inf

Jun-Hyung Cho, Matthias Scheffler

The significant discrepancy between first-principles calculations and experimental analyses for the relaxation of the (001) surface of rhodium has been a puzzle for some years. In this paper we present density functional theory calculations using the local-density approximation and the generalized gradient approximation of the exchange-correlation functional

Marco Picco, Felix Ritort

We study the four dimensional (4D) $\pm J$ Ising spin glass in a magnetic field by using the simulated tempering method recently introduced by Marinari and Parisi. We compute numerically the first four moments of the order parameter probability distribution $P(q)$. We find a finite cusp in the spin-glass susceptibility and strong tendency to paramagnetic ord

K. -t. Leung, R. K. P. Zia

A system consisting of two conservative, oppositely driven species of particles with excluded volume interaction alone is studied on a torus. The system undergoes a phase transition between a homogeneous and an inhomogeneous phase, as the particle densities are varied. Focusing on the inhomogeneous phase with generally unequal numbers of the two species, the

Peter Ingels

This thesis addresses automatic lexical error recovery and tokenization of corrupt text input. We propose a technique that can automatically correct misspellings, segmentation errors and real-word errors in a unified framework that uses both a model of language production and a model of the typing behavior, and which makes tokenization part of the recovery p

Jens Bolte

A detailed discussion of semiclassical trace formulae is presented and it is demonstrated how a regularized trace formula can be derived while dealing only with finite and convergent expressions. Furthermore, several applications of trace formula techniques to quantum chaos are reviewed. Then local spectral statistics, measuring correlations among finitely m

Dongsu Ryu, Hyesung Kang

In the standard theory of the large scale structure formation, matter accretes onto high density perturbations via gravitational instability. Collisionless dark matter forms caustics around such structures, while collisional baryonic matter forms accretion shocks which then halt and heat the infalling gas. Here, we discuss the characteristics, roles, and obs

Dongsu Ryu, Sandip K. Chakrabarti

We present time-dependent solutions of thin, supersonic accretion flows near a black hole and compare them with analytical solutions. Such flows of inviscid, adiabatic gas are characterized by the specific angular momentum and the specific energy. We confirm that for a wide range of above parameters a stable standing shock wave with a vortex inside it forms

M. Tavani, R. Mukherjee, J. R. Mattox, J. Halpern

We report the discovery of a remarkable gamma-ray transient source near the Galactic plane, GRO J1838-04. This source was serendipitously discovered by EGRET in June 1995 with a peak intensity of 4 E(-6) ph/cm/cm/s (for photon energies larger than 100 MeV) and a 5.9 sigma significance. At that time, GRO J1838-04 was the second brightest gamma-ray source in t

L. Bergstrom

An overview is given of high-energy gamma-ray and neutrino astronomy, emphasizing the links between the two fields. With several new large detectors just becoming operational, the TeV gamma-ray and neutrino sky will soon be surveyed with unprecedented sensitivity.

Stephen Serjeant, Steve Rawlings, Mark Lacy

We present preliminary results from HST imaging of radio-loud quasar hosts, covering a ~x100 range in radio luminosity but in a narrow redshift range (0.5 to 0.65). The sample was selected from our new, spectroscopically complete 7C survey and the 3CRR catalogue. Despite the very large radio luminosity range, the host luminosities are only weakly correlated

R. Sadat

The determination of galaxy cluster mass is of great importance since it is directly linked to the well- known problem of dark matter in the Universe and to the cluster baryon content. X-ray observations from satellites have enabled a better understanding of the physics occuring inside clusters, their matter content as well as a detailed description of their

Masashi Chiba, Biman B. Nath

We investigate the hypothesis that $\lyal$ absorption lines arise in two populations of halos --- minihalos of small circular velocity ($V_c \la 55$ km s$^{-1}$) in which star formation and metal production are inhibited by photoionization of the UV background radiation, and large galactic halos ($55 \la V_c \la 250$ km s$^{-1}$) which possess stars and meta

T. Belloni, M. Mendez, A. R. King, M. van der Klis

We have analyzed the X-ray spectra of the microquasar GRS 1915+105, as observed with the PCA on the Rossi XTE, during periods of stable weak emission, outbursts and rapid flaring. We find that the complicated X-ray intensity curve of this source can be described by the rapid removal and replenishment of matter forming the inner part of an optically thick acc

Motokazu Takizawa, Shin Mineshige

Evolutions of X-ray clusters of galaxies are studied by N-body (shell model) + mesh code (TVD) simulations on the assumption of spherical symmetry. We consider a density perturbation of $10^{15} M_{\odot}$ composed of dark matter and gas in cold dark matter dominated universe with the cosmological density parameter, $Ω_0 = 1$ or $0.2$. A shock front appears

Jorg P. Rachen

In a gravitationally unstable universe, the structure of dark matter and galaxies, intergalactic gas and magnetic field can have severe impact on the propagation of ultra high energy cosmic rays (UHECR) (Ryu & Kang, this proceedings). The possible effects include spatial confinement and directional focusing along the supergalactic matter sheets, as well as u

Sanghyeon Chang, Claudio Coriano, R. D. Field

We present parton-level analytical results for the next-to-leading order non-singlet virtual and real corrections to the Drell-Yan differential cross-section. The dependence of the differential cross section on the helicity of the initial state partons is shown explicitly (the spins of the final state partons are summed). The calculation is implemented in di

Cetin Savkli, Frank Tabakin

Pion and kaon observables are calculated using a Dyson-Schwinger Bethe-Salpeter formalism. It is shown that an infrared finite gluon propagator can lead to quark confinement via generation of complex mass poles in quark propagators. Observables, including electromagnetic form factors, are calculated entirely in Euclidean metric for spacelike values of bound

Craig J. Hogan

Spectra of quasars at high redshift with high resolution and high signal-to-noise allow in favorable circumstances detection of absorption by deuterium and ultimately measurement of its primordial abundance. Ultraviolet spectra of high redshift quasars allow measurement of absorption by the most abundant cosmic absorber, singly ionized helium, thereby mappin

Kazusumi Ino

Vacua of two dimensional incompressible system, such as Fractional Quantum Hall system, are characterized by rational conformal field theory. We develop a method to express the wavefunctions of those systems in terms of chiral vertices. We formulate quantum mechanics on those expressions, which reveals the underlying simple structure of the conformal field t

Marcos Alvarez

The Faddeev-Jackiw Hamiltonian Reduction approach to constrained dynamics is applied to the collective coordinates analysis of non-linear waves, and compared with the alternative procedure known as symplectic formalism.

Kenneth Intriligator

We discuss a set of generalized, necessary conditions for non-trivial, interacting fixed points in six dimensional supersymmetric field theories. We use string theory to argue for the existence of infinite families of interacting RG fixed point theories. The theories are based on certain gauge groups and matter content, which we identify, along with addition

M. Dominik

The influence of rotating binary systems on the light curves of galactic microlensing events is studied. Three different rotating binary systems are discussed: a rotating binary lens, a rotating binary source, and the motion of the earth around the sun (parallax effect). The most dramatic effects arise from the motion of a binary lens because of the changes

Markus Peter

A full analytic calculation of the two-loop diagrams contributing to the static potential in QCD is presented in detail. Using a renormalization group improvement, the ``three-loop&#39;&#39; potential in momentum space is thus derived and the third coefficient of the $β$-function for the V-scheme is given. The Fourier transformation to position space is then

Saulo Carneiro

In this letter we quantize a previously proposed non-local lagrangean for the classical dual electrodynamics (Phys.Lett.B 384(1996)197), showing how it can be used to construct probability amplitudes. Our results are shown to agree with those obtained in the context of Schwinger and Zwanzinger formulations, but without necessity of introducing strings.

David I. Kaiser

Analytic results are presented for preheating in both flat and open models of chaotic inflation, for the case of massless inflaton decay into further inflaton quanta. It is demonstrated that preheating in both these cases closely resembles that in Minkowski spacetime. Furthermore, quantitative differences between preheating in spatially-flat and open models

L. Bergstrom, J. Edsjo, M. Kamionkowski

We investigate the improvement in sensitivity to astrophysical point sources of energetic ($\gtrsim1$ GeV) neutrinos which can be achieved with angular and/or energy resolution of the neutrino-induced muon. As a specific example we consider WIMP annihilation in the Sun and in the Earth as a neutrino source. The sensitivity is improved by using the angular an

Jeeva Anandan, Joy Christian, Kazimir Wanelik

This Resource Letter provides a guide to the literature on the geometric angles and phases in classical and quantum physics. Journal articles and books are cited for the following topics: anticipations of the geometric phase, foundational derivations and formulations, books and review articles on the subject, and theoretical and experimental elaborations and

A. N. Sissakian, O. Yu. Shevchenko, S. B. Solganik

We discuss the comment by V.Zeitlin on our recent papers concerning Chern-Simons term generation at finite density.

Hideo Hasegawa

The antiferromagnetic ground state of the half-filled Hubbard model with the doubly degenerate orbital has been studied by using the slave-boson mean-field theory which was previously proposed by the present author. Numerical calculations for the simple cubic model have shown that the metal-insulator transition does not take place except at the vanishing int

H. Kröger

We make a proposal for a Gedanken experiment, based on the Aharonov-Bohm effect, how to measure in principle the zig-zagness of the trajectory of propagation (abberation from its classical trajectory) of a massive particle in quantum mechanics. Experiment I is conceived to show that contributions from quantum paths abberating from the classical trajectory ar

Joy Christian

This is a short metaphysical fable accentuating the conceptual difficulties involved, and succinctly criticizing the approaches pursued since the inception of quantum theory, in dealing with what is known collectively as `the measurement problem.&#39; It includes some landmark references, and has appeared in the special issue of Metaphysical Review dedicated

D. V. Ahluwalia

Book Review of Quantum Field Theory by Lewis H. Ryder. An observation on Ryder&#39;s derivation of Dirac equation is made. The review ends as, &#34;A rare combination of a thorough understanding and appreciation of the essential logical structure of quantum field theory and deep pedagogic skills have intermingled to create a masterpiece on the elementary int

Claudio Ciofi degli Atti, Geoffrey B. West

Some systematic general features of y-scaling structure functions, which are essentially independent of detailed dynamics, are pointed out. Their physical interpretation in terms of general characteristics, such as a mean field description and nucleon-nucleon correlations, is given and their relationship to the momentum distributions illustrated. A new scali

A. Mishra, P. K. Panda, S. Schramm, J. Reinhardt

We compute the vacuum polarisation correction to the binding energy of nuclear matter in the Walecka model using a nonperturbative approach. We first study such a contribution as arising from a ground state structure with baryon-antibaryon condensates. This yields the same results as obtained through the relativistic Hartree approximation of summing tadpole

Stephen C. Locke, Dave Witte Morris

We construct infinitely many connected, circulant digraphs of outdegree three that have no hamiltonian circuit. All of our examples have an even number of vertices, and our examples are of two types: either every vertex in the digraph is adjacent to two diametrically opposite vertices, or every vertex is adjacent to the vertex diametrically opposite to itsel

Edward Dobson, Heather Gavlas, Joy Morris, Dave Witte

It has been shown that there is a Hamilton cycle in every connected Cayley graph on each group G whose commutator subgroup is cyclic of prime-power order. This paper considers connected, vertex-transitive graphs X of order at least 3 where the automorphism group of X contains a transitive subgroup G whose commutator subgroup is cyclic of prime-power order. W

Akihiko Yukie

Let H_1=SL(5), H_2=SL(3), H=H_1 \times H_2. It is known that (G,V) is a prehomogeneous vector space (see [22], [26], [25], for the definition of prehomogeneous vector spaces). A non-constant polynomial δ(x) on V is called a relative invariant polynomial if there exists a character χsuch that δ(gx)=χ(g)δ(x). Such δ(x) exists for our case and is essentially un

M. Frau, I. Pesando, S. Sciuto, A. Lerda

We develop an operator formalism to compute scattering amplitudes of arbitrary bosonic string states in the background of many D-branes. Specifically, we construct a suitable boundary state which we use to saturate the multi-Reggeon vertex in order to obtain the generator of multi-membrane scattering amplitudes. We explicitly show that the amplitudes with $h

Maurizio Martellini, Mauro Zeni

Yang-Mills theory in the first order formalism appears as the deformation of a topological field theory, the pure BF theory. We discuss this formulation at the quantum level, giving the Feynman rules of the BF-YM theory, the structure of the renormalization and checking its uv-behaviour in the computation of the beta-function which agrees with the expected r

P. M. Saffin, E. J. Copeland

We extend work done previously concerning the formation of vortices in a U(1)->1 gauge theory at a first order phase transition to the symmetry breaking SU(2)xU(1)->U(1). It is shown that the collision of bubbles, appearing at the phase transition, allow the possibility for forming non-topological strings associated with the gauge group. The method used also

V. G. Kiselev, Ya. M. Shnir

The interaction of a nontrivial topological field configuration with the external fields is considered. The approach is based on the calculation of the zero modes excitation probability. We consider the interaction of the t&#39;Hooft-Polyakov monopole with an external weak uniform magnetic field and the field of another monopole.

Ti-Ming Chiang, Jacques Distler, Brian R. Greene

We discuss some aspects of perturbative $(0,2)$ Calabi-Yau moduli space. In particular, we show how models with different $(0,2)$ data can meet along various sub-loci in their moduli space. In the simplest examples, the models differ by the choice of desingularization of a holomorphic V-bundle over the same resolved Calabi-Yau base while in more complicated

Seungjoon Hyun, Junsoo Shin, Jae Hyung Yee, Hyuk-jae Lee

We find the static vortex solutions of the model of Maxwell-Chern-Simons gauge field coupled to a (2+1)-dimensional four-fermion theory. Especially, we introduce two matter currents coupled to the gauge field minimally: the electromagnetic current and a topological current associated with the electromagnetic current. Unlike other Chern-Simons solitons the N-

A. Abada, A. H. Bougourzi, B. Si-Lakhal

In this paper we derive the exact expression of the four-spinon contribution to the dynamical correlation function of the spin S= 1/2 anisotropic (XXZ) Heisenberg model in the antiferromagnetic regime. We extensively study its isotropic (XXX) limit and derive perturbatively the Ising one. Our method relies on the quantum affine symmetry of the model, which a

Steven Weinberg

This is a talk presented at the conference ``Historical and Philosophical Reflections on the Foundations of Quantum Field Theory,&#39;&#39; at Boston University, March 1996. It will be published in the proceedings of this conference.

T. Fukuyama, H. Nishiura

We present a massive Majorana neutrino model and see how it is constrained from the solar and atmospheric neutrino deficit experiments. This model incorporates the seesaw mechanism and Peccei-Quinn symmetry. Its consequence to the neutrinoless double beta decay is also discussed.

B. Holdom

We emphasize the role that anomalous power-law scaling of 4-fermion operators, occurring in the presence of new strong interactions, could have in the generation of quark and lepton masses.

T. Ishikawa, Y. Kurihara, M. Skrzypek, Z. Was

We discuss theoretical predictions for W-pair production and decay at LEP2 and higher energies in a form suitable for comparison with raw data. We present a practical framework for calculating uncertainties of predictions given by the KORALW and grc4f Monte Carlo programs. As an example we use observables in the $s\bar s c\bar c$ decay channel: the total fou

R. M. Davidson, M. Burkardt

We estimate the magnitude of charge symmetry breaking effects in deep inelastic scattering from nuclei. The resulting contribution to systematic uncertainties in hadronic determinations of $sin^2θ_W$ are found to be less than the current experimental accuracy, but may be important in the analyses of more precise future experiments. We expect the largest nucl

S. Davidson, J. Ellis

We construct lepton flavour-dependent and basis-independent measures of R-parity violation in the minimal supersymmetric extension of the Standard Model (MSSM). We work in the context of exact supersymmetry, neglecting the effects of Higgs vacuum expectation values and soft supersymmetry-breaking terms. We devote particular attention to appropriate choices o

Zhonghan Feng, Denes Molnar, Laszlo Pal Csernai

Possibility to detect DCC fluctuations is discussed. It is shown that interactions with quark background and dissipative effects due to interactions in the chiral field may result in damping of fluctuations. Since the magnitude of fluctuations depends strongly on the initial state and speed of chiral phase transition accurate evaluation of all modifying proc

P. F. Harrison, D. H. Perkins, W. G. Scott

The phenomenological case for threefold maximal lepton mixing is strengthened by more detailed comparison with existing data. The atmospheric neutrino data are self-consistent and in good agreement with the threefold maximal mixing prediction R = 2/3 (chi-squared/dof = 4.3/5, CL = 51%). Including partially con- tained event data, the zenith angle dependence

M. Buza, W. L. van Neerven

The most important part of the order $α_s^2$ corrections to the charm component of the charged-current structure functions $F_2(x,Q^2)$ and $F_3(x,Q^2)$ have been calculated. This calculation is based on the asymptotic form of the heavy-quark coefficient functions corresponding to the higher order corrections to the W-boson-gluon fusion process. These coeffi

A. Capella, A. Kaidalov, C. Merino, D. Pertermann

Gribov theory is applied to investigate the shadowing effects in the structure functions of nuclei. In this approach these effects are related to the process of diffractive dissociation of a virtual photon. A model for this diffractive process, which describes well the HERA data, is used to calculate the shadowing in nuclear structure functions. A reasonable

F. Klingl, W. Weise

Based on an effective Lagrangian which combines chiral SU(3) dynamics with vector meson dominance, we have developed a model for the s-wave vector meson-nucleon scattering amplitudes. We use this as an input for the low energy part of the current-current correlation function in nuclear matter. Its spectrum enters directly in the ``left hand side&#39;&#39; of

V. Barone, T. Calarco, A. Drago

We calculate the double-spin transverse asymmetries for the Drell-Yan lepton pair production in p-p and p-anti p collisions. We assume the transverse and the longitudinal polarization densities to be equal at a very small scale, as it is suggested by confinement model results. Using a global fit for the longitudinal distributions, we find transverse asymmetr

G. Lopez Castro, J. H. Munoz

Two-body non-leptonic decays of B mesons into PT and VT modes are calculated using the non-relativistic quark model of Isgur et al.. The predictions obtained for $B \to πD^*_2, ρD_2^*$ are a factor of $3\sim 5$ below present experimental upper limits. Interesting patterns are obtained for ratios of B decays involving mesons with different spin excitations an

T. D. Bakeyev, M. I. Polikarpov, A. A. Slavnov, A. I. Veselov

Different aspects of bozonization algorithm proposed by Slavnov are tested by numerical simulations of a one dimensional toy model.

C. Adloff

A study is presented of the process gamma p -->XY, where there is a large rapidity gap between the systems X and Y. Measurements are made of the differential cross section as a function of the invariant mass mx of the system produced at the photon vertex. Results are presented at centre of mass energies of W_gp = 187 GeV and W_gp = 231 GeV, both where the pr