June 1997 arXiv papers — page 12

Gustavo Dotti, Aneesh V. Manohar

Sufficient conditions are proven for 't Hooft's consistency conditions to hold at points in the moduli space of supersymmetric gauge theories. Known results for anomaly matching in supersymmetric QCD are rederived as a sample application of the results. The results can be used to show that the anomaly matching conditions hold for s-confining theories

Ken Kiers, Amarjit Soni

We study the q^2 dependence of the exclusive decay mode B \to D tau \bar{nu} in type II two Higgs doublet models and show that this mode may be used to put stringent bounds on tan(beta)/m_H. There are currently rather large theoretical uncertainties in the q^2 distribution, but these may be significantly reduced by future measurements of the analogous distri

Mark A Samuel, TESFAYE Abraha

In the light of recent experimental observation of the radiation amplitude zero (RAZ) in Wγproduction by CDF at Fermilab, we consider its consequences. is the RAZ unique to the standard model? Although it is not for neutrino-electron scattering, in the case of d-ubar scattering which is the case of experimental interest, observation of the RAZ implies that t

B. Holdom

It has recently been shown that strong interactions underlying electroweak symmetry breaking will induce four-fermion amplitudes proportional to m_t^2, which in turn will influence a variety of flavor changing processes. We argue that the size of these effects are likely to be far below the current experimental bounds.

Kaoru Hagiwara, Dieter Haidt, Seiji Matsumoto

We update our previous work on an analysis of the electroweak data by including new and partly preliminary data available up to the 1996 summer conferences. The new results on the Z partial decay widths into b and c hadrons now offer a consistent interpretation of all data in the minimal standard model. The value extracted for the strong interaction coupling

L. Mankiewicz, A. Saalfeld, T. Weigl

We propose a systematic approximation scheme for solving GLAP evolution equations at small Bjorken-$x$. The approximate solutions interpolate smoothly between hard (singular as $x^{-(1+λ)}$, $λ> 0$) and soft (singular at most as $x^{-1}$) initial conditions and may be applied in a wide range of $Q^2$. The small-$x$ behavior of $F_2^p(x,Q^2)$ which is extract

Alasdair James Gill

The O(4) linear sigma model of the chiral transition in QCD is similar to models of the superfluid transition in 4He and 3He. Observations of vortex formation in superfluid helium have recently improved the understanding of the dynamics of such transitions. This is exploited to estimate the baryon density in the central region of a heavy ion region and the r

Johan André

The second-order QCD matrix elements give a very good agreement with experimental data on the angular distributions of the four-jet events in e+e- collisions at the Z0 resonance energy. Unfortunately the description of the sub-jet structure is quite poor. The alternative approach, parton showers, gives a good description of the sub-jet structure but is worse

B. I. Ermolaev, S. I. Troyan

We show that for small x and in the double logarithmic approximation (DLA) g_2 can be expressed through derivative of g_1 with respect to logarithm of the QCD coupling. Therefore the small-x behavior of the both structure functions is similar. The analytical expression for flavor nonsinglet structure function g_1 is presented and its asymptotical behaviour i

Frank Würthwein

Using 3.3 Million $B\bar B$ pairs accumulated with the CLEO detector CLEO has measured ${\cal B}(B^0\to K^+π^-) = (1.5^{+ 0.5}_{-0.4}\pm 0.1\pm 0.1)\times 10^{-5}$, ${\cal B}(B^+\to K^0π^+) = (2.3^{+1.1}_{-1.0}\pm 0.2\pm 0.2)\times 10^{-5}$, and ${\cal B}(B^+\to η^{'}K^+) = (7.8^{+ 2.7}_{-2.2}\pm 1.0)\times 10^{-5}$. These constitute the first observatio

S. V. Chervon, V. M. Zhuravlev, V. K. Shchigolev

The exact solutions in the standard inflationary model based on the self-interacting scalar field minimally coupled to gravity are considered. The shape's freedom of the self-interacting potential $V(ϕ)$ is postulated to obtain a new set of the exact solutions in the framework of Friedmann-Robertson-Walker Universes. The general solution was found in the

Fabio Scardigli

The spacetime foam structure is reviewed briefly (topogical fluctuations and virtual black hole possibility; equation of state of the foam). A model of space foam at the surface of the event horizon is introduced. The model is applied to the calculus of the number of states of a black hole, of its entropy and of other thermodynamical properties. A formula fo

Peter F. Arndt, Thomas Heinzel, Vladimir Rittenberg

The steady states of the two-species (positive and negative particles) asymmetric exclusion model of Evans, Foster, Godreche and Mukamel are studied using Monte Carlo simulations. We show that mean-field theory does not give the correct phase diagram. On the first-order phase transition line which separates the CP-symmetric phase from the broken phase, the d

N. Caticha, O. Kinouchi

The ideas of optimization of learning algorithms in Artificial Neural Networks are reviewed emphasizing generic properties and the online implementations are interpreted from a biological perspective. A simple model of the relevant subsidiary variables needed to improve learning in artificial feedforward networks and the `time ordering' of the appearance

M. L. Kulic, A. I. Buzdin, L. N. Bulaevskii

The recently reported coexistence of a magnetic order, with the critical temperature T_M=35 μ*K, and superconductivity, with the critical temperature T_S=207 m*K, in AuIn_2 is studied theoretically. It is shown that superconducting (S) electrons and localized nuclear magnetic moments (LM's) interact dominantly via the contact hyperfine (EX) interaction,

S. -H. Lee, S-W. Cheong

Commensurability effects for nickelates have been studied by the first neutron experiments on La5/3Sr1/3NiO4. Upon cooling, this system undergoes three successive phase transitions associated with quasi-two-dimensional (2D) commensurate charge and spin stripe ordering in the NiO$_2$ planes. The two lower temperature phases (denoted as phase II and III) are s

A. I. M. Rae, E. M. Forgan, R. A. Doyle

In the HTC superconductor BSCCO, local measurements of magnetic field in the mixed state show sharp changes as a function of applied field or temperature, which have been interpreted as evidence for a first-order flux-lattice melting (or sublimation) transition . The entropy associated with such a transition was calculated from the magnetisation jumps using

P. Schmitteckert, T. Schulze, C. Schuster, P. Schwab

Using the density matrix renormalization group algorithm, we investigate the lattice model for spinless fermions in one dimension in the presence of a strong interaction and disorder. The phase sensitivity of the ground state energy is determined with high accuracy for systems up to a size of 60 lattice constants. This quantity is found to be log-normally di

Naoum Karchev

A long-wavelength, low-frequency effective theory is obtained from $t_1-t_2-J$ model. The action is written in terms of two-component bose spinor fields (CP^1 fields) and two spinless Fermi fields. The generalized CP^1 model is invariant under U(1) gauge transformations. The bose fields and one of the Fermi fields have charge +1 while the other Fermi field h

German Sierra, Miguel A. Martin-Delgado

We introduce a set of discrete modular transformations $T_\ell,U_\ell$ and $S_\ell$ in order to study the relationships between the different phases of the Heisenberg ladders obtained with all possible exchange coupling constants. For the 2 legged ladder we show that the $RVB$ phase is invariant under the $S_\ell$ transformation, while the Haldane phase is i

Juan M. Lopez, Miguel A. Rodriguez

We study the local scaling properties of driven interfaces in disordered media modeled by the Edwards-Wilkinson equation with quenched noise. We find that, due to the super-rough character of the interface close to the depinning transition, the local width exhibits an anomalous temporal scaling. It does not saturate at a characteristic time $t_s(l) \sim l^z$

E. Pitard, T. Garel, H. Orland

We study a homopolymer model of a protein chain, where each monomer carries a dipole moment. To mimic the geometry of the peptidic bond, these dipoles are constrained to be locally perpendicular to the chain. The tensorial character of the dipolar interaction leads naturally to a (tensorial) liquid crystal-like order parameter. For non chiral chains, a mean

D. Vollhardt

In 1996 Lee, Osheroff and Richardson received the Nobel Prize for their 1971 discovery of superfluid helium 3 -- a discovery which opened the door to the most fascinating system known in condensed matter physics. The superfluid phases of helium 3, originating from pair condensation of helium 3 atoms, turned out to be the ideal test-system for many fundamenta

Jesper Lykke Jacobsen, Hans C. Fogedby

We study the spin-spin correlation function in or near the T=0 ground state of the antiferromagnetic Ising model on a triangular lattice. At zero temperature its modulation on the sublattices gives rise to two Bragg peaks in the structure factor, and a known expression for the algebraic decay of correlations enables us to examine the form of the diffusive sc

Yupeng Wang, Jianhui Dai, Zhanning Hu, Fu-Cho Pu

We propose an integrable Kondo problem in a one-dimensional (1D) $t-J$ model. With the open boundary condition of the wave functions at the impurity sites, the model can be exactly solved via Bethe ansatz for a class of $J_{R,L}$ (Kondo coupling constants) and $V_{L,R}$ (impurity potentials) parametrized by a single parameter $c$. The integrable value of $J_

Arturo Trujillo

This paper presents a compilation procedure which determines internal and external indices for signs in a unification based grammar to be used in improving the computational efficiency of lexicalist chart generation. The procedure takes as input a grammar and a set of feature paths indicating the position of semantic indices in a sign, and calculates the fix

Adwait Ratnaparkhi

This paper presents a statistical parser for natural language that obtains a parsing accuracy---roughly 87% precision and 86% recall---which surpasses the best previously published results on the Wall St. Journal domain. The parser itself requires very little human intervention, since the information it uses to make parsing decisions is specified in a concis

J. L. Gilson, T. Dombre

Intermittency in the Gledzer-Okhitani-Yamada (GOY) model of turbulence is explained in terms of collisions of coherent soliton-like structures with a random background issuing from the desintegration of their predecessors. This two-fluid picture is substantiated by the elucidation of local dynamical mechanisms leading to anomalous growth of coherent structur

Otto Chkhetiani

The evolution of correlation characteristics in homogeneous helical turbulence is considered. Additional K'arm'an-Howarth type equations, describing the evolution of the mixed correlation tensor of the velocity and vorticity are obtained. In the helical scaling region, the solution of obtained equation gives the exact relation between antisymmetric c

Ted von Hippel, G. D. Bothun, R. A. Schommer

We discuss the luminosity function of SNe Ia under the assumption that recent evidence for dispersion in this standard candle is related to variations in the white dwarf mass function (WDMF) in the host galaxies. We develop a simple parameterization of the WDMF as a function of age of a stellar population and apply this to galaxies of different morphological

K. Krisciunas

We have produced a data base of V-band and B-band night-sky brightness measurements rather evenly spread out over the course of a whole sunspot cycle from September 1985 to August 1996. Almost all the data were obtained at the 2800-m level of Mauna Kea using the same telescope, same photomultiplier tube, filters, and diaphragm, thus minimizing various source

James B. Stevens, Pablo Reig, Malcolm J. Coe, David H. Buckely

We report optical and infrared observations of the massive X-ray binary system 4U1145-619 (V801 Cen) which show that the circumstellar disc of the Be star component is in decline. Infrared J,H,K,L magnitudes of V801Cen have been monitored from 1993 March to 1996 April. H alpha spectra have been obtained throughout the same period. We find that both the infra

F. Legrand, D. Kunth, J. M. Mas-Hesse, J. Lequeux

Long-slit observations of the blue compact galaxy Haro 2 have been performed to detect the Halpha emission originating in the partially ionized wind outflowing at 200 km/s, that had been previously detected with the Hubble Space Telescope. A shallow broadening of the Halpha line wings has been observed, consistent with the existence of an expanding shell. Th

E. F. Borra

I discuss the modalities of zenith observing with LMTs, their limitations and advantages. The main limitation comes from the relatively small regions of the sky that LMTs can access. The main advantage comes from low cost, for inexpensive large LMTs can be dedicated to very specialized goals. Large surveys, cosmological studies, variability studies are prime

G. M. Voit, M. Donahue

The close correlation between cooling flows and emission-line nebulae in clusters of galaxies has been recognized for over a decade and a half, but the physical reason for this connection remains unclear. Here we present deep optical spectra of the nebula in Abell 2597, one of the nearest strong cooling-flow clusters. These spectra reveal the density, temper

M. Montuori, F. Sylos Labini, A. Gabrielli, A. Amici

We report the correlation analysis of various redshift surveys which shows that the available data are consistent with each other and manifest fractal correlations (with dimension $D \simeq 2$) up to the present observational limits ($\approx 150 \hmp$) without any tendency towards homogenization. This result points to a new interpretation of the number coun

J. P. Beaulieu, D. D. Sasselov

We present a differential studies of 550 Cepheids observed in the LMC and the SMC by the EROS microlensing survey.

J. P. Beaulieu, M. Krockenberger, D. D. Sasselov, C. Renault

We report the discovery of eleven beat Cepheids in the Small Magellanic Cloud, using data obtained by the EROS microlensing survey. Four stars are beating in the fundamental and first overtone mode (F/1OT), seven are beating in the first and second overtone (1OT/2OT). The SMC F/1OT ratio is systematically higher than the LMC F/1OT, while the 1OT/2OT period r

Yoshiaki Taniguchi, Nobuo Arimoto, Takashi Murayama, Aaron S. Evans

We present the results of our observing program on near infrared spectroscopy of high-redshift quasars which have been undertaken both at Kitt Peak National Observatory and at Mauna Kea Observatory, University of Hawaii. These data are utilized for studying the epoch of major star formation in high-redshift quasar hosts.

S. A. Laurent-Muehleisen, R. I. Kollgaard, E. D. Feigelson

The Rosat - Green Bank BL Lac sample consists of 119 objects and smoothly bridges the gap between the previously disparate subclasses of radio- and X-ray-selected objects. Further study of this sample will provide useful constraints to the unified scheme and help determine what, if any, modifications are necessary.

John Terning

I present a set of theories which display non-trivial `t Hooft anomaly matching for QCD with $F$ flavors. The matching theories are non-Abelian gauge theories with "dual" quarks and baryons, rather than the purely confining theories of baryons that `t Hooft originally searched for. The matching gauge groups are required to have an $F\pm 6$ dimensional repres

Don N. Page

In a stationary axisymmetric spacetime, the angular velocity of a stationary observer that Fermi-Walker transports its acceleration vector is also the angular velocity that locally extremizes the magnitude of the acceleration of such an observer, and conversely if the spacetime is also symmetric under reversing both t and phi together. Thus a congruence of N

Pei-Ming Ho, Miao Li, Yong-Shi Wu

We study the off-diagonal blocks in the M(atrix) model that are supposed to correspond to open strings stretched between a Dp-brane and a Dp'-brane. It is shown that the spectrum, including the quantum numbers, of the zero modes in the off-diagonal blocks can be determined from the index theorem and unbroken supersymmetry, and indeed reproduces string th

K. Becker, M. Becker, J. Polchinski, A. Tseytlin

In matrix theory the effective action for graviton-graviton scattering is a double expansion in the relative velocity and inverse separation. We discuss the systematics of this expansion and subject matrix theory to a new test. Low energy supergravity predicts the coefficient of the $v^6/r^{14}$ term, a two-loop effect, in agreement with explicit matrix mode

Horacio E. Castillo, Claudio de C. Chamon, Eduardo Fradkin, Paul M. Goldbart

The multifractal scaling exponents are calculated for the critical wave function of a two-dimensional Dirac fermion in the presence of a random magnetic field. It is shown that the problem of calculating the multifractal spectrum maps into the thermodynamics of a static particle in a random potential. The multifractal exponents are simply given in terms of t

Mirjam Cvetic, Finn Larsen

We present the wave equation for a minimally coupled scalar field in the background of a rotating four-dimensional black hole that is parametrized by its mass, angular momentum, and four independent U(1) charges. The near horizon structure is identical to the five-dimensional case, and suggestive of an underlying description in string theory that is valid in

Randall J. Splinter, Adrian L. Melott, Sergei F. Shandarin, Yasushi Suto

We explore some of the effects that discreteness and two-body scattering may have on N-body simulations with ``realistic'' cosmological initial conditions. We use an identical subset of particles from the initial conditions for a $128^3$ Particle-Mesh (PM) calculation as the initial conditions for a variety P$^3$M and Tree code runs. We investigate the effec

Ingemar Bengtsson, Ted Jacobson

The structure of boundaries between degenerate and nondegenerate solutions of Ashtekar's canonical reformulation of Einstein's equations is studied. Several examples are given of such "phase boundaries" in which the metric is degenerate on one side of a null hypersurface and non-degenerate on the other side. These include portions of flat spa

Rui Neves

We show that the strength of the leading non-perturbative effects in non-critical string theory is of the order $e^{-O(1/{β_{st}})}$. We show how this restricts the space of consistent theories. We also identify non-critical one dimensional D-instantons as dynamical objects which exchange closed string states and calculate the order of their size.

Charles Gale

We first review the calculations of low invariant mass dilepton production in relativistic heavy ion collisions, using effective hadronic Lagrangians. We go through some of the theoretical techniques used in this kinematical region and we consider some of the appropriate experimental measurements. Moving up to the intermediate invariant mass region, we point

Richard E. Borcherds

In this paper we try to define the higher dimensional analogues of vertex algebras. In other words we define algebras which we hope have the same relation to higher dimensional quantum field theories that vertex algebras have to one dimensional quantum field theories (or to ``chiral halves'' of two dimensional quantum field theories). The main idea i

Richard M. Haas

Real scalar field models incorporating asymmetric double well potentials will decay to the state of lowest energy. While the eventual nature of the system can be discerned, the determination of the dynamics of the bubble wall provides many difficulties. In the present study we investigate numerically the evolution of spherically symmetric expanding bubbles c

A. P. Kobushkin

The differential cross section, the tensor analyzing power, $T_{20}$, and the polarization transfer, $κ_0$, in $^{12}C(d,p)$ breakup at relativistic energy are calculated within a model which incorporates multiple scattering and Pauli principle at quark level. It is shown that the rescattering and quark exchange affect drastically the polarization observable

Francois Pointet

We study the link between a compact hypersurface in $¶^{n+1}$ and the set of all its tangent planes. In this context, we identify $¶^{n+1}$ to the set of linear subspaces of codimension one by orthogonal complementarity. This gives rise to a kind of duality which has already been studied Bruce and Romerro-Fuster, and relates a hypersurface to the set of its

M. Chaichian, W. F. Chen, V. Ya. Fainberg

We make a detailed investigation on the quantum corrections to Chern-Simons spinor electrodynamics. Starting from Chern-Simons spinor quantum electrodynamics with the Maxwell term $-1/(4γ){\int}d^3x F_{μν}F^{μν}$ and by calculating the vacuum polarization tensor, electron self-energy and on-shell vertex, we explicitly show that the Ward identity is satisfied

B. Guiderdoni, F. R. Bouchet, J. L. Puget, G. Lagache

In this letter, we estimate how much starlight was absorbed by dust and released in the infrared during the formation of galaxies. New constraints are set on this so-far hidden history by the recent detection of the Cosmic Infrared Background (CIB) built up from the accumulated light of faint sources (and revisited here). By means of a semi-analytical model

Marco A. Diaz, Jorge C. Romao, Jose W. F. Valle

We show that the minimal R-parity breaking model characterized by an effective bilinear violation of R-parity in the superpotential is consistent with minimal N=1 supergravity unification with radiative breaking of the electroweak symmetry and universal scalar and gaugino masses. This one-parameter extension of the MSSM-SUGRA model provides therefore the sim

Ernest Ma, Probir Roy

If one assumes solar and LSND neutrino oscillations to explain the corresponding data, then the atmospheric neutrino deficit cannot be accommodated within the Standard Model with three light flavors, unless one ignores the data's zenith-angle dependence. We propose a novel solution to this problem by postulating large anomalous diagonal $ν_τ$-quark inter

A. Mikovic, V. Radovanovic

We calculate the complete one-loop effective action for a spherical scalar field collapse in the large radius approximation. This action gives the complete trace anomaly, which beside the matter loop contributions, receives a contribution from the graviton loops. Our result opens a possibility for a systematic study of the back-reaction effects for a real bl

I. Borukhov, D. Andelman, H. Orland

Adsorption of charged polymers (polyelectrolytes) from a semi-dilute solution to a charged surface is investigated theoretically. We obtain simple scaling laws for (i) the amount of polymer adsorbed to the surface, Gamma, and (ii) the width of the adsorbed layer D, as function of the fractional charge per monomer p and the salt concentration c_b. For strongl

Lu-Ming Duan, Guang-Can Guo

We construct generally applicable short-time perturbative expansions for some fidelities, such as the input-output fidelity, the entanglement fidelity, and the average fidelity. Successive terms of these expansions yield characteristic times for the damping of the fidelities involving successive powers of the Hamiltonian. The second-order results, which repr

C. S. Kim, Y. G. Kim, K. Y. Lee

We study the distribution function of the b-quark for inclusive semileptonic B decays in the framework of the parton model. We compare the functional behavior of the fragmentation inspired function and the Gaussian ACCMM function, and discuss their validity. Using the HQET parameters, we can critically test these models.

T. Haugset, H. Haugerud, F. Ravndal

The one-loop effective potential for non-relativistic bosons with a delta function repulsive potential is calculated for a given chemical potential using functional methods. After renormalization and at zero temperature it reproduces the standard ground state energy and pressureas function of the particle density. At finite temperatures it is found necessary

Zurab Kakushadze, Gary Shiu

In this paper we consider compactifications of type I strings on Abelian orbifolds. We discuss the tadpole cancellation conditions for the general case with D9-branes only. Such compactifications have (perturbative) heterotic duals which are also realized as orbifolds (with non-standard embedding of the gauge connection). The latter have extra twisted states

A. De Castro, A. Restuccia

A Higgs mechanism for Abelian theories over non-trivial background flat connections is proposed. It is found that the mass generated for the spin 1 excitation is the same as the one obtained from the standard Higgs mechanism over trivial backgrounds, however, the dynamical structure of the action for the Higgs scalar is completely different from the usual ap

Akihiko Tomita, Tsutomu T. Takeuchi, Tadashi Usui, Mamoru Saito

We examined the general characteristics of the Kiso Ultra-violet Excess Galaxies (KUGs). We present for the first time the quantitative expressions for the criteria of the KUGs; the boundary color separating the KUGs from the non-KUGs is (B-V)_{T} = 0.74 and the KUG degrees of UV strength are found to correlate with the mean (B-V)_{T} colors. We investigate

N. Wex

In binary radio pulsars with a main-sequence star companion, the spin-induced quadrupole moment of the companion gives rise to a precession of the binary orbit. As a first approximation one can model the secular evolution caused by this classical spin-orbit coupling by linear-in-time changes of the longitude of periastron and the projected semi-major axis of

L. Accardi, S. V. Kozyrev, I. V. Volovich

The dynamics of the spin-boson Hamiltonian is considered in the stochastic approximation. The Hamiltonian describes a two-level system coupled to an environment and is widely used in physics, chemistry and the theory of quantum measurement. We demonstrate that the method of the stochastic approximation which is a general method of consideration of dynamics o

C. Sanchez, S. A. Dassie, A. M. Baruzzi, E. P. M. Leiva

Some aspects of direct ion transfer across the water/1,2-dichloroethane are analyzed using a very simple model based on thermodynamic considerations. It was concluded that ion solvation by water molecules may occur in some particular cases in the organic phase, delivering an important contribution to the Gibbs free energy of ion transfer between the aqueous

Timothy E. Holy

Conventional statistics begins with a model, and assigns a likelihood of obtaining any particular set of data. The opposite approach, beginning with the data and assigning a likelihood to any particular model, is explored here for the case of points drawn randomly from a continuous probability distribution. A scalar field theory is used to assign a likelihoo

A. Yelkhovsky

Recent calculations of the order (Zα)^4(m/M)Ry pure recoil correction to hydrogen energy levels are critically revised. The origins of errors made in the previous works are elucidated. In the framework of a successive approach, we obtain the new result for the correction to S levels. It amounts to -16.4 kHz in the ground state and -1.9 kHz in the 2S state.

R. D. Benguria, M. C. Depassier

We consider the bifurcation problem u'' + λu = N(u) with two point boundary conditions where N(u) is a general nonlinear term which may also depend on the eigenvalue λ. A new derivation of a variational principle for the lowest eigenvalue λis given. This derivation makes use only of simple algebraic inequalities and leads directly to a more explicit

John David Crawford, Anandhan Jayaraman

The amplitude equation for an unstable electrostatic wave is analyzed using an expansion in the mode amplitude $A(t)$. In the limit of weak instability, i.e. $γ\to 0^+$ where $γ$ is the linear growth rate, the nonlinear coefficients are singular and their singularities predict the dependence of $A(t)$ on $γ$. Generically the scaling $|A(t)|=γ^{5/2}r(γt)$ as

Daniel R. Phillips, Silas R. Beane, Thomas D. Cohen

We examine several zero-range potentials in non-relativistic quantum mechanics. The study of such potentials requires regularization and renormalization. We contrast physical results obtained using dimensional regularization and cutoff schemes and show explicitly that in certain cases dimensional regularization fails to reproduce the results obtained using c

C. Quesne

The three-particle Hamiltonian obtained by replacing the two-body trigonometric potential of the Sutherland problem by a three-body one of a similar form is shown to be exactly solvable. When written in appropriate variables, its eigenfunctions can be expressed in terms of Jack symmetric polynomials. The exact solvability of the problem is explained by a hid

Guido Cognola, Paola Lecca

Using standard coordinates, the Maxwell equations in the Reissner-Nordström geometry are written in terms of a couple of scalar fields satisfying Klein-Gordon like equations. The density of states is derived in the semi-classical approximation and the first quantum corrections to the black hole entropy is computed by using the brick-wall model.

Kwanghoon Hahm, KyoungHo Han, H. J. Shin

We study the composite Skyrme model, proposed by Cheung and Gürsey, introducing vector mesons in a chiral Lagrangian. We calculate the static properties of baryons and compare with results obtained from models without vector mesons.

KyoungHo Han, H. J. Shin

Two dimensional QCD is bosonized to be an integrably deformed Wess-Zumino-Witten model under proper limit. Fermions are identified having indices of the Grassmann manifold. Conditions for integrability are analyzed and their physical meanings are discussed. We also address the nature of the exactly solvable part of the theory and find the infinitely many con

L. N. Granda, S. D. Odintsov

We study exact renormalization group (RG) in O(4) gauged supergravity using the effective average action formalism. The nonperturbative RG equations for cosmological and newtonian coupling constants are found. It is shown the existence of (nonstable) fixed point of these equations. The solution of RG equation for newtonian coupling constant is qualitatively

Takehisa Fujita, Hidenori Takahashi

We calculate for the first time the finite size corrections in the massive Thirring model. This is done by numerically solving the equations of periodic boundary conditions of the Bethe ansatz solution. It is found that the corresponding central charge extracted from the $1/L$ term is around 0.4 for the coupling constant of ${g_0}=-{π\over 4} $ and decreases

Davison E. Soper

I discuss the one jet inclusive jet cross section, d sigma /dE_T emphasizing the concept of infrared safety and the cone definition of jets. Then I estimate the size of power corrections to the jet cross section, which become important at smaller values of E_T.

J. R. Forshaw

Some selected topics in photoproduction are reviewed. In particular, the focus is on quasi-real photon-proton scattering as measured at HERA. Single & dijet rates and jet profiles are discussed, as are open charm production and inelastic charmonium production. The many intriguing theoretical issues which can be addressed through study of these processes are

A. G. Grunfeld, M. C. Rocca

A quantum relativistic model is proposed to represent the confining potential of $c \bar{c}$ and $b \bar{b}$ mesons by using the Klein Gordon oscillator. We have solved the two-body problem obtaining the eigenvalues and the corresponding mass spectra, which fit very well with experimental data. We compare the results of our model with others obtained from di

E. V. Shuryak, A. R. Zhitnitsky

Motivated by recent CLEO measurements of the B-->η' K decay, we evaluate gluon/charm content of the eta' meson using the interacting instanton liquid model of the QCD vacuum. Our result is very large due to the strong field of small-size instantons. We show that it provides quantitative explanations of the CLEO data on the B-->η' K decay rate (as

Mikhail Braun, Gian Paolo Vacca

This is a draft describing the calculation of the evolution of the gluon density in $x$ from an initial value $x=x_{0}=0.01$ to smaller values, up to $x=10^{-8}$ in the hard pomeron formalism with a running coupling introduced on the basis of the bootstrap equation. The obtained gluon density is used to calculate the singlet part of the proton structure func

S. Rai Choudhury

The Forward-backward asymmetry in the angular distribution of $e^+e^-$ is studied in the process $B\to e^+e^- and \bar{B}\to \bar{X}_d e^+e^-$ . The possibility of observing CP violation through the asymmetries in these two processes is examined.

Q. H. Zhang, W. Q. Chao, C. S. Gao

The effects of two kinds of coherent lengths, the wave packet length of the emitter and the radius of the coherent source, on pion spectrum distribution are studied. It is shown that both coherent lengths can cause abundant pions at low momentum, but the DCC size effects on pion spectrum distribution is more important. So observing abundant pions at low mome

Andrzej Czarnecki, Kirill Melnikov, Nikolai Uraltsev

We present the complete O(alpha_s^2) corrections to the Wilson coefficient of the unit operator in the zero-recoil sum rule for the B-->D* transition. We include both perturbative and power-suppressed nonperturbative effects in a manner consistent with the operator product expansion. The impact of these corrections on |V_cb| extracted from semileptonic B-->D

B. Machet

I show, in the framework of a SU(2)left x U(1) gauge theory for J=0 mesons expressed as scalar or pseudoscalar di-quark fields, that: - the existence, at the fermionic level, of a complex mixing matrix of the Kobayashi-Maskawa type is not a sufficient condition for electroweak mass eigenstates to be different from CP eigenstates; - unitarity constrains this

ZEUS Collaboration

This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- π^+) π^+ $ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with

S. V. Chervon

In this review article we consider three most important sources of the gravitational field of the Early Universe: self-interacting scalar field, chiral field and gauge field. The correspondence between all of them are pointed out. More attention is payed to nonlinear scalar field source of gravity. The progress in finding the exact solutions in inflationary

Istvan Racz, Jozsef Zsigrai

The properties of a transformation previously considered for generating new perfect-fluid solutions from known ones are further investigated. It is assumed that the four-velocity of the fluid is parallel to the stationary Killing field, and also that the norm and the twist potential of the stationary Killing field are functionally related. This case is compl

P. S. Letelier, W. M. Vieira

The occurrence of chaos for test particles moving around Schwarzschild black holes perturbed by a special class of gravitational waves is studied in the context of the Melnikov method. The explicit integration of the equations of motion for the homoclinic orbit is used to reduce the application of this method to the study of simple graphics.

David Langlois

The observed CMBR dipole is generally interpreted as a Doppler effect arising from the motion of the Earth relative to the CMBR frame. An alternative interpretation, proposed in the last years, is that the dipole results from ultra-large scale isocurvature perturbations. We examine this idea in the context of open cosmologies and show that the isocurvature i

H. Balasin, W. Israel

A general analysis of the gravitational dynamics of a medium with a continuous distribution of vorticity indicates that the answer to the question raised in the title is affirmative, contrary to a recent claim.

J. K. Lawson

This paper presents a generalization of symplectic geometry to a principal bundle over the configuration space of a classical field. This bundle, the vertically adapted linear frame bundle, is obtained by breaking the symmetry of the full linear frame bundle of the field configuration space, and it inherits a generalized symplectic structure from the full fr

T. A. Costi

We present a technique for calculating non-equilibrium Green functions for impurity systems with local interactions. We use an analogy to the calculation of response functions in the x-ray problem.The initial state and the final state problems, which correspond to the situations before and after the disturbance (an electric or magnetic field, for example) is

M. Steiner, M. Fabrizio, Alexander O. Gogolin

Quasi-one-dimensional spin-Peierls and spin-ladder systems are characterized by a gap in the spin-excitation spectrum, which can be modeled at low energies by that of Dirac fermions with a mass. In the presence of disorder these systems can still be described by a Dirac fermion model, but with a random mass. Some peculiar properties, like the Dyson singulari

Igor Zutic, Oriol T. Valls

We present a method to determine the nodal structure of the energy gap of unconventional superconductors such as high $T_c$ materials. We show how nonlinear electrodynamics phenomena in the Meissner regime, arising from the presence of lines on the Fermi surface where the superconducting energy gap is very small or zero, can be used to perform ``node spectro

Debashish Chowdhury, Kingshuk Ghosh, Arnab Majumdar, Shishir Sinha

We calculate the distribution of the distance headways (i.e., the instantaneous gap between successive vehicles) as well as the distribution of instantaneous distance between successive jams in the Nagel-Schreckenberg (NS) model of vehicular traffic. When the maximum allowed speed, $V_{max}$, of the vehicles is larger than unity, over an intermediate range o