March 1994 arXiv papers — page 3

Lajos Diosi

The evolution of the reduced density operator $ρ$ of Brownian particle is discussed in single collision approach valid typically in low density gas environments. This is the first succesful derivation of quantum friction caused by {\it local} environmental interactions. We derive a Lindblad master equation for $ρ$, whose generators are calculated from differ

N. Kawashima, J. E. Gubernatis, H. G. Evertz

Two cluster algorithms, based on constructing and flipping loops, are presented for worldline quantum Monte Carlo simulations of fermions and are tested on the one-dimensional repulsive Hubbard model. We call these algorithms the loop-flip and loop-exchange algorithms. For these two algorithms and the standard worldline algorithm, we calculated the autocorre

Peter Kostaedt, Mario Liu

The measured rate of the 3^He A-B transition depends on the diameter of the experimental cell. Theoretically, this can only be explained by a direct drag on the interface exerted by the lateral walls, leading to a pressure discontinuity across the interface. This has not been considered before, either here or in similar circumstances. The general hydrodynami

G. Gyuk, M. S. Turner

In the standard picture of big-bang nucleosynthesis the yields of D, $^3$He, $^4$He, and $^7$Li only agree with their inferred primordial abundances if the fraction of critical density contributed by baryons is between $0.01h^{-2}$ and $0.02h^{-2}$ ($h$ is the present value of the Hubble constant in units of $100\kms\Mpc^{-1}$). This is the basis of the very

D. S. Salopek, J. M. Stewart, K. M. Croudace

Beginning with a relativistic action principle for the irrotational flow of collisionless matter, we compute higher order corrections to the Zel'dovich approximation by deriving a nonlinear Hamilton-Jacobi equation for the velocity potential. It is shown that the velocity of the field may always be derived from a potential which however may be a multi-va

Ramesh Narayan, Insu Yi

We consider viscous rotating accretion flows in which most of the viscously dissipated energy is stored as entropy rather than being radiated. Such advection-dominated flows may occur when the optical depth is either very small or very large. We obtain a family of self-similar solutions where the temperature of the accreting gas is nearly virial and the flow

A. G. A. Brown, E. J. de Geus, P. T. de Zeeuw

Walraven photometry of established and probable members of the Orion OB1 association is presented. Effective temperature, surface gravity, luminosity and mass are derived for all stars, using atmosphere models by Kurucz (1979). Absolute magnitudes are calculated using the Straizys and Kuriliene (1981) tables. Distance moduli and visual extinctions are determ

K. -J. Schramm. U. Borgeest, D. Kühl, J. von Linde, M. D. Linnert

HQM is an optical broad-band photometric monitoring program carried out since September 1988. We use a CCD camera at the MPIA 1.2$\,$m telescope. Fully automatic photometric reduction relative to stars in the frames is done within a few minutes after each exposure, thus interesting brightness changes can be followed in detail. The typical photometric error i

K. -J. Schramm, U. Borgeest, D. Kühl, J. v. Linde

HQM is an optical broad-band photometric monitoring program carried out since Sept.~1988. We use a CCD camera equipped to the MPIA 1.2$\,$m telescope. Fully automatic photometric reduction relative to stars in the frames is done within a few minutes after each exposure, thus interesting brightness changes can be followed in detail. The typical photometric er

Rosemary A. Mardling

Globular clusters cores harbour many low-mass X-ray binaries, cataclysmic variables, and millisecond pulsar binaries which are likely to have been formed via the process of tidal capture. Tidal capture binaries were originally thought to be responsible for halting core collapse and for subsequent re-expansion via the process of ``binary heating''. Th

Biswajoy Brahmachari, Probir Roy

The 1-loop evolution of couplings in the minimal supersymmetric standard model, extended to include baryon nonconserving $(B\!\!\!/)$ operators through explicit $R$-parity violation, is considered keeping only $B\!\!\!/$ superpotential terms involving the maximum possible number of third generation superfields. If all retained Yukawa couplings $Y_i$ are requ

J. Ellis, N. E. Mavromatos, D. V. Nanopoulos

We review our approach to time and quantum dynamics based on non-critical string theory, developing its relationship to previous work on non-equilibrium quantum statistical mechanics and the microscopic arrow of time. We exhibit specific non-factorizing contributions to the ${\nd S}$ matrix associated with topological defects on the world sheet, explaining t

Tim R. Morris

The functional flow equations for the Legendre effective action, with respect to changes in a smooth cutoff, are approximated by a derivative expansion; no other approximation is made. This results in a set of coupled non-linear differential equations. The corresponding differential equations for a fixed point action have at most a countable number of soluti

Chang-Hwan Lee, G. E. Brown, Mannque Rho

The critical density for kaon condensation in ``nuclear star" matter is computed up to two-loop order {\it in medium} (corresponding to next-to-next-to-leading order in chiral perturbation theory in free space) with a heavy-baryon effective chiral Lagrangian whose parameters are determined from $KN$ scattering and kaonic atom data. To the order considere

Karl-Peter Marzlin

A Reference is corrected. (We derive the Fermi coordinate system of an observer in arbitrary motion in an arbitrary weak gravitational field valid to all orders in the geodesic distance from the worldline of the observer. In flat space-time this leads to a generalization of Rindler space for arbitrary acceleration and rotation. The general approach is applie

Jacek Dziarmaga

We apply the adiabatic approximation to investigate the low energy dynamics of vortices in the parity invariant double self-dual Higgs model with only mutual Chern-Simons interaction. When distances between solitons are large they are particles subject to the mutual interaction. The dual formulation of the model is derived to explain the sign of the statisti

Zoltan Fodor, Karl Jansen

In this letter we extent the overrelaxation algorithm, known to be very efficient in gauge theories, to coupled gauge-Higgs systems with a particular emphasis on the update of the radial mode of the Higgs field. Our numerical tests of the algorithm show that the autocorrelation times can be reduced substantially.

Abhay Ashtekar, Donald Marolf, Jose Mourao

A summary of the known results on integration theory on the space of connections modulo gauge transformations is presented and its significance to quantum theories of gauge fields and gravity is discussed. The emphasis is on the underlying ideas rather than the technical subtleties.

Christopher J. Bishop, Peter Jones

Let G be a non-elementary, finitely generated Kleinian group, Lambda(G) its limit set and Omega(G) = S \ Lambda(G) (S = the sphere) its set of discontinuity. Let delta(G) be the critical exponent for the Poincaré series and let Lambda_c be the conical limit set of G. Suppose Omega_0 is a simply connected component of Omega(G). We prove that (1) delta(G) = di

Thomas M. Fiola, John Preskill, Andrew Strominger, Sandip P. Trivedi

Black hole evaporation is investigated in a (1+1)-dimensional model of quantum gravity. Quantum corrections to the black hole entropy are computed, and the fine-grained entropy of the Hawking radiation is studied. A generalized second law of thermodynamics is formulated, and shown to be valid under suitable conditions. It is also shown that, in this model, a

Ivan Cherednik

The elliptic-matrix quantum Olshanetsky-Perelomov problem is introduced for arbitrary root systems by means of an elliptic generalization of the Dunkl operators. Its equivalence with the double affine generalization of the Knizhnik-Zamolodchikov equation (in the induced representations) is established.

Pavel Etingof, Kostantin Styrkas

In this paper we study integrability and algebraic integrability properties of certain matrix Schrödinger operators. More specifically, we associate such an operator (with rational, trigonometric, or elliptic coefficients) to every simple Lie algebra g and every representation U of this algebra with a nonzero but finite dimensional zero weight subspace. The

D. B. Fairlie, A. N. Leznov

It is shown that the general solution of a homogeneous Monge-Ampère equation in $n$-dimensional space is closely connected with the exactly (but only implicitly) integrable system \frac {\partial ξ_{j}}{\partial x_0}+\sum_{k=1}^{n-1} ξ_{k} \frac {\partial ξ_{j}}{\partial x_{k}}=0 \label{1} Using the explicit form of solution of this system it is possible to

E. Elizalde, S. D. Odintsov

The renormalization-group improved effective potential ---to leading-log and in the linear curvature approximation--- is constructed for ``finite'' theories in curved spacetime. It is not trivial and displays a quite interesting, exponential-like structure ---in contrast with the case of flat spacetime where it coincides with the classical potential.

D. Kapetanakis, G. Koutsoumbas, A. Lukas, P. Mayr

We examine an extension of the ideas of quantum cosmology and, in particular, the proposal of Hartle and Hawking for the boundary conditions of the Universe, to models which incorporate Yang-Mills fields. Inhomogeneous perturbations about a homogeneous, isotropic minisuperspace background model are considered, by expanding the Yang-Mills fields in harmonics

C. Viallet

We resolve the `baxterization' problem with the help of the automorphism group of the Yang-Baxter (resp. star-triangle, tetrahedron, \dots) equations. This infinite group of symmetries is realized as a non-linear (birational) Coxeter group acting on matrices, and exists as such, {\em beyond the narrow context of strict integrability}. It yields among oth

Melanie Becker

The coupling of $N=1$ SCFT of type $(4m,2)$ to two-dimensional supergravity can be formulated non-perturbatively in terms of a discrete super-eigenvalue model proposed by Alvarez-Gaumé, et al. We derive the superloop equations that describe, in the double scaling limit, the non-perturbative solution of this model. These equations are equivalent to the double

G. Bimonte, G. Lozano

We derive gauge covariant self-dual equations for the $SU(2) \times U(1)_Y$ theory of electro-weak interactions and show that they admit solutions describing a periodic lattice of Z-strings.} \newpage

Johannes Blümlein

The QED radiative corrections are calculated in the leading log approximation up to ${\cal O}(α^2)$ for different definitions of the kinematical variables using jet measurement, the 'mixed' variables, the double angle method, and a measurement based on $θ_e$ and $y_{JB}$. Higher order contributions due to exponentiation of soft radiation are included

R. Aleksan, B. Kayser, D. London

If the Standard Model explanation of CP violation is correct, then measurements of CP-violating asymmetries in $B$ meson decays can in principle determine the entire quark mixing matrix.

Luis E. Ibanez, G. G. Ross

The structure of the quark and lepton masses and mixing angles provides one of the few windows we have on the underlying physics generating the \sm. In an attempt to identify the underlying symmetry group we look for the simplest gauge extension of the SUSY standard model capable of generating the observed structure. We show that the texture structure and hi

Wolfgang Lucha, Franz F. SCHÖberl

By explicit solution of the one-loop finiteness conditions for gauge and quartic scalar-boson self-interaction coupling constants, a particular class of grand unified theories with vanishing Yukawa couplings as well as vanishing one-loop renormalization-group beta functions is constructed.

R. Baier, R. Kobes

The self-consistent determination of the damping rate of a fast moving fermion in a hot QED plasma is reexamined. We argue how a detailed investigation of the analytic properties of the retarded fermion Green's function motivated by the cutting rules at finite temperature may resolve ambiguities related to the proper definition of the mass-shell conditio

T. Morii, S. Tanaka, T. Yamanishi

Two-spin asymmetries $A_{LL}^{π^0}$ are calculated for various types of spin-dependent gluon distributions. It is concluded that the E581/704 data on $A_{LL}^{π^0}$ do not necessarily rule out the large gluon polarization but restrict severely the $x$ dependence of its distribution. Moreover, $A_{LL}^{J/ψ}$ are calculated for the forthcoming test of spin-dep

T. Morii, S. Tanaka, T. Yamanishi

Effects of the spin-dependent gluon distributions on J/$ψ$ productions in polarized ep and pp collisions are investigated. These productions serve as a very clean probe of the spin-dependent gluon distributions in a proton.

A. Yu. Ignatiev, G. C. Joshi

We have considered the effect of the reduction of the solar neutrino flux on earth due to the deflection of the charged neutrino by the magnetic field of the solar convective zone. The antisymmetry of this magnetic field about the plane of the solar equator induces the anisotropy of the solar neutrino flux thus creating the deficit of the neutrino flux on th

J. Ohnemus

The processes $p p \rightarrow V_1 V_2 + X \rightarrow \ell_1 \bar \ell_1 \ell_2 \bar \ell_2 + X$, where $V_i = W^{\pm}$ or $Z$ and $\ell_i$ denotes a lepton, are calculated to ${\cal O}(α_s)$. Total and differential cross sections, with acceptance cuts imposed on the final state leptons, are given for the Tevatron and LHC center of mass energies. Inclusive

T. Kobayashi, D. Suematsu, Y. Yamagishi

Gauge coupling unification is studied in the MSSM with non-universal soft supersymmetry breaking terms. If gaugino masses are sufficiently smaller than scalar soft masses and the scalar soft masses have also certain types of non-universality, gauge coupling unification scale can be larger than $3\times 10^{16}$~GeV even within the MSSM contents. String unifi

The CLEO Collaboration

Branching ratios for the dominant Cabibbo-suppressed decays of the $τ$ lepton have been measured by CLEO~II in $e^+ e^-$ annihilation at CESR ($\sqrt{s} \sim 10.6$~GeV) using kaons with momenta below $0.7\ \rm GeV/c$. The inclusive branching ratio into one charged kaon is $(1.60 \pm 0.12 \pm 0.19)\%$. For the exclusive decays, $B(τ\to K^-) = (0.66 \pm 0.07 \

The CLEO Collaboration

Using the CLEO~II detector at CESR, we have measured the ratio of branching fractions ${\cal B}(D_s^+ \to ϕe^+ ν)/{\cal B}(D_s^+ \to ϕπ^+) = 0.54\pm 0.05\pm 0.04$. We use this measurement to obtain a model dependent estimate of ${\cal B}(D_s^+ \to ϕπ^+)$.

The CLEO Collaboration

We have measured the vector-pseudoscalar mass splitting $M(D_s^{*+})-M(D_s^+) = 144.22\pm 0.47\pm 0.37 MeV$, significantly more precise than the previous world average. We minimize the systematic errors by also measuring the vector-pseudoscalar mass difference $M(D^{*0})-M(D^0)$ using the radiative decay $D^{*0}\rightarrow D^0γ$, obtaining $[M(D_s^{*+})-M(D_

The CLEO Collaboration

Using the CLEO II detector at CESR, we observe 500 $Λl^+$ pairs consistent with the semileptonic decay $Λ_c \to Λl^+ ν_{l}$. We measure $σ(e^+ e^- \to Λ_c X) \dot {cal B}(Λ_c^+ \to Λl ν_{l}) =4.77 \pm 0.25 \pm 0.66 $pb. Combining with the charm semileptonic width and the lifetime of the $Λ_c$, we also obtain ${\cal B}(Λ_c \to p K^- π^+)$. We find no evidence

The CLEO Collaboration

Using the CLEO-II detector, we have obtained evidence for a new meson decaying to $D^0 K^+$. Its mass is $2573.2^{+1.7}_{-1.6}\pm 0.8\pm 0.5$ {}~MeV/$c^2$ and its width is $16^{+5}_{-4}\pm 3$~MeV/$c^2$. Although we do not establish its spin and parity, the new meson is consistent with predictions for an $L=1$, $S=1$, $J_P=2^+$ charmed strange state.

Mark Alford

We argue that the sharp-cutoff Wilson renormalization group provides a powerful tool for the analysis of second-order and weakly first-order phase transitions. In particular, in a computation no harder than the calculation of the 1-loop effective potential, we show that the Wilson RG yields the fixed point couplings and critical exponents of 3-dimensional $O

G. Wanders

We investigate massless fermion production by a two-dimensional dilatonic black hole. Our analysis is based on the Bogoliubov transformation relating the outgoing fermion field observed outside the black hole horizon to the incoming field present before the black hole creation. It takes full account of the fact that the transformation is neither invertible n

E. Ben-Naim, P. L. Krapivsky

The one-dimensional contact process is analyzed by a cluster approximation. In this approach, the hierarchy of rate equations for the densities of finite length empty intervals are truncated under the assumption that adjacent intervals are not correlated. This assumption yields a first order phase transition from an active state to the adsorbing state. Despi

V. N. Muthukumar, G. Baskaran

We extend the correlated electron model of Baskaran [Mod. Phys. Lett. {\bf B5}, 643(1991)] to the case of coupled layers. We show that the nature of the non-Fermi liquid ground state leads to the absence of electron-like quasiparticles at the Fermi surface, thereby suppressing coherent transport of electrons between the coupled layers (``confinement'&#39

Marco Picco, Felix Ritort

We study the order parameter distribution P(q) in the 4d Ising spin glass with $\pm J$ couplings in a magnetic field. We also compare these results with simulations for the infinite ranged model (i.e. SK model.) Then we analyse our numerical results in the framework of the droplet picture as well as in the mean field approach.

Y. Ohta, T. Shimozato, R. Eder, S. Maekawa

Using a proposed numerical technique for calculating anomalous Green's functions characteristic of superconductivity, we show that the low-lying excitations in a wide parameter and doping region of the two-dimensional $t$$-$$J$ model are well described by the picture of dressed Bogoliubov quasiparticles in the BCS pairing theory. The pairing occurs predo

Wentian Li, Thomas G. Marr, Kunihiko Kaneko

In this paper, we review the literature on statistical long-range correlation in DNA sequences. We examine the current evidence for these correlations, and conclude that a mixture of many length scales (including some relatively long ones) in DNA sequences is responsible for the observed 1/f-like spectral component. We note the complexity of the correlation

Yong -Cheol Kim, Peter A. Fox, Sabatino Sofia, Pierre Demarque

In an attempt to understand the properties of convective energy transport in the solar convection zone, a numerical model has been constructed for turbulent flows in a compressible, radiation-coupled, non-magnetic, gravitationally stratified medium using a realistic equation of state and realistic opacities. The time-dependent, three-dimensional hydrodynamic

R. J. Nemiroff, W. A. D. T. Wickramasinghe, J. P. Norris, C. Kouveliotou

We have searched for gravitational-lens induced echoes between gamma-ray bursts (GRBs) in NASA's orbiting {\it Compton} Gamma Ray Observatory's Burst and Transient Source Experiment (BATSE) data. The search was conducted in two phases. In the first phase we compared all GRBs in a brightness complete sample of the first 260 GRBs with recorded angular

Be-lok Hu, Andrew Matacz

Using the influence functional formalism we show how to derive a generalized Einstein equation in the form of a Langevin equation for the description of the backreaction of quantum fields and their fluctuations on the dynamics of curved spacetimes. We show how a functional expansion on the influence functional gives the cumulants of the stochastic source, an

Matthias Doerrzapf

We derive a set of recursion formulae to construct singular vectors for the $N=2$ (untwisted) algebra, by using the approach of Bauer, di Francesco, Itzykson and Zuber. Applying these formulae, we obtain explicit expressions for the charged singular vectors and for a class of uncharged singular vectors.

P. Aspinwall

In this paper the relationship between the classical description of the resolution of quotient singularities and the string picture is reviewed in the context of N=(2,2) superconformal field theories. A method for the analysis of quotients locally of the form C^d/G where G is abelian is presented. Methods derived from mirror symmetry are used to study the mo

M. Barriola

We propose a new mechanism to generate baryons. Electroweak strings produced at the electroweak phase transition will introduce anomalous currents through interactions of the strings with the background electromagnetic field and through changes in the helicity of the string network. These anomalous currents will produce fluctuations in the baryon and lepton

Jacek Dziarmaga

We investigate zero modes of a multivortex background which are due to the energetic degeneracy of the planar static n-vortex solution in Bogomol'nyi limit of the Abelian Higgs model parametrised by a set of 2n real parameters. The zero modes take the form of waves travelling with a speed of light independently along each of the vortices irrespectively t

Michael M. Tung

The massive one-loop {\it QCD} corrections to the production cross sections of We present the massive one-loop {\it QCD} corrections to the production cross sections of polarized quarks in the annihilation process $e^+e^-\to q\bar{q}(g)$ for bottom, top, and charm quarks. From the full analytical expressions for the production cross sections, Schwinger-type

J. Bolz, P. Kroll, J. G. Koerner

A method is proposed to extend the hard scattering picture of Brodsky and Lepage to transitions between hadrons with orbital angular momentum l=0 and l=1. The use of covariant spin wave functions turns out to be very helpful in formulating that method. As a first application we construct a light-cone wave function of the nucleon resonance $N^*(1535)$ in the

R. D. Benguria, M. C. Depassier

We consider travelling wave solutions of the reaction diffusion equation with quintic nonlinearities $u_t = u_{xx} + μu (1 -u ) ( 1 +αu + βu^2 +γu^3)$. If the parameters $α, β$ and $γ$ obey a special relation, then the criterion for the existence of a strong heteroclinic connection can be expressed in terms of two of these parameters. If an additional restri

Tom H. Koornwinder

A tutorial introduction is given to q-special functions and to q-analogues of the classical orthogonal polynomials, up to the level of Askey-Wilson polynomials.

Antti J. Niemi, O. Tirkkonen

The structure of equivariant cohomology in non-abelian localization formulas and topological field theories is discussed. Equivariance is formulated in terms of a nilpotent BRST symmetry, and another nilpotent operator which restricts the BRST cohomology onto the equivariant, or basic sector. A superfield formulation is presented and connections to reducible

Ali Yegulalp

We study a class of models in which $N$ flavors of massless fermions on the half line are coupled by an arbitrary orthogonal matrix to $N$ rotors living on the boundary. Integrating out the rotors, we find the exact partition function and Green's functions. We demonstrate that the coupling matrix must satisfy a certain rationality constraint, so there is

Michio Kaku

In this review article, we review the recent developments in constructing string field theories that have been proposed, all of which correctly reproduce the correlation functions of two-dimensional string theory. These include: (a) free fermion field theory (b) collective string field theory (c) temporal gauge string field theory (d) non-polynomial string f

T. Strobl

In two dimensions a large class of gravitational systems including, e.g., $R^2$-gravity can be quantized exactly also when coupled dynamically to a Yang-Mills theory. Some previous considerations on the quantization of pure gravity theories are improved and generalized.

Michael R. Douglas

We reinterpret U(N) Chern-Simons-Witten theory quantized on a torus as a free fermion system. Its Hilbert space and some observables are simply related to those of group quantum mechanics, even at finite N and k. Its large N limit can be described using techniques developed for matrix quantum mechanics and two-dimensional Yang-Mills theory. We discuss the bo

A. N. Leznov

A general method for the construction of solutions of the d'Alambertian and double d'Alambertian (harmonic and bi-harmonic) equations with local dependence of arbitrary functions upon two independent arguments is proposed. The connection between solutions of this kind and self-dual configurations of gauge fields having no singularities is established

Dmitri Kharzeev, Andrei Leonidov

We propose to study the space-time picture of hadronization by looking at the angular distribution of photons emitted in the process e^+ e^- \rightarrow K^0 {\bar{K}}^0 γat DAΦNE energies. it is shown that the angular distributions are quite sensitive to the hadronization length.

P. Aurenche, T. Becherrawy, E. Petitgirard

We apply the retarded/advanced formalism of real time field theory to the QED or QED like case. We obtain a general expression for the imaginary part of the two-point correlation function in terms of discontinuities. The hard loop expansion is derived. The formalism is used to extract the divergent part of the soft fermion loop contribution to the real soft

Nick Evans

LEP precision measurements of the $Zb\bar{b}$ vertex coupling are sufficiently accurate to see the non-oblique corrections from the heavy gauge boson responsible for the large top mass in standard extended tecnicolour models. If the ETC couplings are strong the techni-fermion condensate may be enhanced by several orders of magnitude allowing a top mass of or

Jorma Louko, Donald Marolf

We investigate the space ${\cal M}$ of classical solutions to Witten's formulation of 2+1 gravity on the manifold ${\bf R} \times T^2$. ${\cal M}$ is connected, but neither Hausdorff nor a manifold. However, removing from ${\cal M}$ a set of measure zero yields a connected manifold which is naturally viewed as the cotangent bundle over a non-Hausdorff ba

F. Arias de Saavedra, J. Boronat, A. Polls, A. Fabrocini

A microscopic calculation of the effective mass of one $^4$He impurity in homogeneous liquid $^3$He at zero temperature is performed for an extended Jastrow--Slater wave function, including two-- and three--body dynamical correlations and also backflow correlations between the $^4$He atom and the particles in the medium. The effective mass at saturation dens

Dingping Li, Stéphane Ouvry

The new definition of fractional statistics given by Haldane can be understood in some special cases in terms of the Riemann-Roch theorem.

R. A. Jalabert, J. -L. Pichard, C. W. J. Beenakker

The conductance of a ballistic quantum dot (having chaotic classical dynamics and being coupled by ballistic point contacts to two electron reservoirs) is computed on the single assumption that its scattering matrix is a member of Dyson's circular ensemble. General formulas are obtained for the mean and variance of transport properties in the orthogonal

Varun Sahni, B. S. Sathyaprakash, Sergei F. Shandarin

We apply the adhesion approximation to study the formation and evolution of voids in the Universe. Our simulations -- carried out using 128$^3$ particles in a cubical box with side 128 Mpc -- indicate that the void spectrum evolves with time and that the mean void size in the standard COBE-normalised Cold Dark Matter (hereafter CDM) model with $h_{50} = 1,$

Brian Chaboyer, P. Demarque

A large number of stellar evolution models with [Fe/H] = -2.3 and -3.3 have been calculated in order to determine the primordial $^7$Li abundance and to test current stellar evolution models by a comparison to the extensive database of Li abundances in extremely metal poor halo stars observed by Thorburn (1994). Standard models do a good job of fitting the o

Ben Moore, Carlos Frenk, George Efstathiou, Will Saunders

We investigate the clustering of galaxies in the QDOT redshift survey of IRAS galaxies. We find that the redshift space two-point correlation function is well approximated by a power-law of slope -1.11+\-0.09, with clustering length 3.87+\-0.32 Mpc/h out to pair separations of 25 Mpc\h. On scales larger than 40 Mpc/h, the correlation function is consistent w

A. Kusenko, R. Shrock

We discuss complex rephasing invariants of charged lepton and neutrino mass matrices and associated theorems which determine in general (i) the number of physically meaningful phases in these matrices and (ii) which elements of these matrices can be rendered real by rephasings. New results are presented on higher order complex invariants and the application

A. Blotz, M. Praszalowicz, K. Goeke

Within the semibosonized SU(3)-NJL model the mass splittings of baryons and the axial vector coupling constants of the nucleon are evaluated. The mass splittings of the hyperons are reproduced with great accuracy if second order corrections in $m_s$ are taken into account. New corrections to the axial vector currents coming from the subleading terms in the $

M. Asorey, F. Falceto, J. L. Lopez, G. Luzon

The universality of radiative corrections to the gauge coupling constant $k$ of Chern-Simons theory is studied in a very general regularization scheme. We show that the effective coupling constant $k$ induced by radiative corrections depends crucially on the balance between the ultraviolet behavior of scalar and pseudoscalar terms in the regularized action.

M. Asorey, F. Falceto, J. L. Lopez, G. Luzon

We introduce a new family of gauge invariant regularizations of Chern-Simons theories which generate one-loop renormalizations of the coupling constant of the form $k\to k+2 s c_v$ where $s$ can take any arbitrary integer value. In the particular case $s=0$ we get an explicit example of a gauge invariant regularization which does not generate radiative corre

M. A. Lledo, A. Resturccia

The theory of the string in interaction with a dilaton background field is analyzed. In the action considered, the metric in the world sheet of the string is the induced metric, and the theory presents second order time derivatives. The canonical formalism is developed and it is showed that first and second class constraints appear. The degrees of freedoom a

B. Jurco, P. Stovicek

Coherent states are introduced and their properties are discussed for all simple quantum compact groups. The multiplicative form of the canonical element for the quantum double is used to introduce the holomorphic coordinates on a general quantum dressing orbit and interpret the coherent state as a holomorphic function on this orbit with values in the carrie

M. Cadoni, S. Mignemi

We discuss the properties of lorentzian and euclidean black hole solutions of a generalized 2-dim dilaton-gravity action containing a modulus field, which arises from the compactification of heterotic string models. The duality symmetries of these solutions are also investigated.

A. Bouzas, D. Zappala

We evaluate the inclusive semileptonic B decay spectrum as a function of the final-state hadrons energy to second order in the inverse quark mass expansion and tree level in $α_{s}$. We argue that there is an energy interval below the $c$ production threshold that could be used to determine $V_{ub}$.

Alon E. Faraggi

I discuss the problem of proton decay, from dimension four, five and six operators, in superstring derived standard--like models. I classify the sectors that produce color triplet superfields which may generate proton decay from dimension five and six operators. I show that for two of these sectors there exist a unique superstring doublet--triplet splitting

D. C. Salisbury, L. C. Shepley

We discuss a general formalism for numerically evolving initial data in general relativity in which the (complex) Ashtekar connection and the Newman-Penrose scalars are taken as the dynamical variables. In the generic case three gauge constraints and twelve reality conditions must be solved. The analysis is applied to a Petrov type \{1111\} planar spacetime

Jeffrey Yepez, Guy P. Seeley, Norman Margolus

A condensed history and theoretical development of lattice-gas automata in the Boltzmann limit is presented. This is provided as background to set up the context for understanding the implementation of the lattice-gas method on two parallel supercomputers: the MIT cellular automata machine CAM-8 and the Connection Machine CM-5. The macroscopic limit of two-d

Sen-Ben Liao, Janos Polonyi

It is argued that universality is severely limited for models with multiple fixed points. As a demonstration the renormalization group equations are presented for the potential and the wave function renormalization constants in the $O(N)$ scalar field theory. Our equations are superior compared with the usual approach which retains only the contributions tha

M. Franz, S. Teitel

Monte Carlo simulations of 2D vortex lattice melting in a thin superconducting film (or alternatively an array of Josephson junctions) are performed in the London limit. Finite size scaling analyses are used to make a detailed test of the dislocation mediated melting theory of KTNHY. We find that the melting transition is weakly first order, with a jump in t

G. Lazarides, C. Panagiotakopoulos

We construct a $SU(3)^3$ supersymmetric gauge theory with a common gauge coupling g. Spontaneous breaking of this gauge group at a scale $M_X=1.3\times10^{16} $GeV gives naturally rise exactly to the Minimal Supersymmetric Standard Model $(MSSM)$ and consequently to the experimentally favored values of $sin^2θ_w$ and $α_s$.The gauge hierarchy problem is natu

Ngee Pong Chang

Chiral symmetry undergoes a metamorphosis at $T_c$. For $T < T_c$, the usual Noether charge, $\Qa$, is dynamically broken by the vacuum. Above $T_c$, chiral symmetry undergoes a subtle change, and the Noether charge \underline{\em morphs} into $\Qbeta$, with the thermal vacuum now becoming invariant under $\Qbeta$. This vacuum is however not invariant under

Anatol N. Kirillov, Nadejda A. Liskova

We study the Bethe ansatz equations for a generalized $XXZ$ model on a one-dimensional lattice. Assuming the string conjecture we propose an integer version for vacancy numbers and prove a combinatorial completeness of Bethe&#39;s states for a generalized $XXZ$ model. We find an exact form for inverse matrix related with vacancy numbers and compute its deter

Xiao-Biao Lin

For a singularly perturbed system of reaction--diffusion equations, assuming that the 0th order solutions in regular and singular regions are all stable, we construct matched asymptotic expansions for formal solutions to any desired order in $ε$. The formal solution shows that there is an invariant manifold of wave-front-like solutions that attracts other ne

K. Saito, A. W. Thomas

An explicit quark model, based on a mean field description of non-overlapping nucleon bags bound by the self-consistent exchange of $\sigma$, $\omega$ and $\rho$ mesons, is used to investigate the properties of both nuclear and neutron matter. We establish a clear understanding of the relationship between this model, which incorporates the internal structure

W. Koepf, E. M. Henley, M. Alberg

The role of mesons, particularly the pion, in the structure of nucleons is reviewed and investigated. Since quark-antiquark pairs are likely to ``transform&#34; into mesons at large distances, mesons are expected to contribute to nucleon structure. Their effects on the Gottfried sum rule, on the strangeness content of the nucleon, and on the spin of the nucl

Alphonse P. Magnus

Generalized Jacobi polynomials are orthogonal polynomials related to a weight function which is smooth and positive on the whole interval of orthogonality up to a finite number of points, where algebraic singularities occur. The influence of these singular points on the asymptotic behaviour of the recurrence coefficients is investigated.

Donald Marolf, Jose M. Mourao

We show that the Ashtekar-Isham extension of the classical configuration space of Yang-Mills theories (i.e. the moduli space of connections) is (topologically and measure-theoretically) the projective limit of a family of finite dimensional spaces associated with arbitrary finite lattices. These results are then used to prove that the classical configuration

Daniel Arnaudon

Invertible universal R-matrices of quantum Lie algebras do not exist at roots of unity. There exist however quotients for which intertwiners of tensor products of representations always exist, i.e. R-matrices exist in the representations. One of these quotients, which is finite dimensional, has a universal R-matrix. In this paper, we answer the following que

Amine M. El Gradechi, Luis M. Nieto

Generalized coherent states provide a means of connecting square integrable representations of a semi-simple Lie group with the symplectic geometry of some of its homogeneous spaces. In the first part of the present work this point of view is extended to the supersymmetric context, through the study of the OSp(2/2) coherent states. These are explicitly const