February 1994 arXiv papers — page 2

David Garcia, Ricardo A. Jimenez, Joan SOLA, Wolfgang Hollik

Within the framework of the MSSM, we compute the electroweak one-loop supersymmetric quantum corrections to the width $Γ(t\rightarrow W^{+}\, b)$ of the canonical main decay of the top quark. The results are presented in two on-shell renormalization schemes parametrized either by $α$ or $G_F$. While in the standard model, and in the Higgs sector of the MSSM,

Charles R. Evans, Jason S. Coleman

We observe critical phenomena in spherical collapse of radiation fluid. A sequence of spacetimes $\cal{S}[η]$ is numerically computed, containing models ($η\ll 1$) that adiabatically disperse and models ($η\gg 1$) that form a black hole. Near the critical point ($η_c$), evolutions develop a self-similar region within which collapse is balanced by a strong, i

J. A. Nieminen, T. Ala- Nissila

Dynamics of spreading of small droplets on surfaces has been studied by the molecular dynamics method. Simulations have been performed for mixtures of solvent and dimer, and solvent and tetramer droplets. For solvent particles and dimers, layering occurs leading to stepped droplet shapes. For tetramers such shapes occur for relatively deep and strong surface

G. Ramirez-Santiago, Jorge V. José

We present a detailed study of the critical properties of the 2-D XY model with maximal frustration in a square lattice. We use extensive Monte Carlo simulations to study the thermodynamics of the spin and chiral degrees of freedom, concentrating on their correlation functions. The gauge invariant spin-spin correlation functions are calculated close to the c

Sang-Yoon Kim

We numerically study the scaling behavior of period doublings at the zero-coupling critical point in a four-dimensional volume-preserving map consisting of two coupled area-preserving maps. In order to see the fine structure of period doublings, we extend the simple one-term scaling law to a two-term scaling law. Thus we find a new scaling factor $δ_3$ $(=1.

O. Derzhko, A. Moina

For 1D s=1/2 anisotropic XY model in transverse field with Dzyaloshinskii-Moriya interaction using Jordan-Wigner transformation the thermodynamical functions, static spin correlation functions, transverse dynamical spin correlation function and connected with it transverse dynamical susceptibility have been obtained. It has been shown that Dzyaloshinskii-Mor

Christina M. Bird

Formation theories for central dominant galaxies in clusters require them to be located at the minimum of the cluster gravitational potential. However, 32\% (8 out of 25) of the clusters with more than 50 measured redshifts have central galaxies with significant velocity offsets (with respect to other cluster members). By studying their velocity distribution

Adrian L. Melott

I report on controlled comparison of gravitational approximation schemes linear/lognormal/adhesion/frozen-flow/Zel'dovich(ZA) and ZA's second--order generalization. In the last two cases we also created new versions of the approximation by truncation, i.e., by finding an optimum smoothing window (see text) for the initial conditions. The Zel'dovi

C. G. Boyd, B. Grinstein

The most general Lagrangian consistent with chiral, heavy quark, and strong interaction symmetries to order $1/M$ and to linear order in the SU(3) vector and axial currents is presented. Two new dimensionful and five dimensionless couplings arise at this order. The heavy to light flavor changing current is derived to the same order, giving rise to two additi

Nicolai Reshetikhin, Alexander Varchenko

The quasiclassical asymptotics of the Knizhnik-Zamolodchikov system is studied. Solutions to this system in this limit are related naturally to Bethe vectors in the Gaudin model of spin chains.

David K. Arrowsmith, Julyan H. E. Cartwright, Alexis N. Lansbury, Colin M. Place

We investigate the bifurcations and basins of attraction in the Bogdanov map, a planar quadratic map which is conjugate to the Hénon area-preserving map in its conservative limit. It undergoes a Hopf bifurcation as dissipation is added, and exhibits the panoply of mode locking, Arnold tongues, and chaos as an invariant circle grows out, finally to be destroy

L. Biferale, A. Lambert, R. Lima, G. Paladin

We study a shell model for the energy cascade in three dimensional turbulence at varying the coefficients of the non-linear terms in such a way that the fundamental symmetries of Navier-Stokes are conserved. When a control parameter $ε$ related to the strength of backward energy transfer is enough small, the dynamical system has a stable fixed point correspo

R. W. Nunes, David Vanderbilt

We describe a real-space approach to the calculation of the properties of an insulating crystal in an applied electric field, based on the iterative determination of the Wannier functions (WF's) of the occupied bands. It has been recently shown that a knowledge of the occupied WF's allows the calculation of the spontaneous (zero-field) electronic pol

A. L. Barabanov

Experimental data on angular distributions of gamma rays emitted from binary and ternary spontaneous fission of $^{252}{\rm Cf}$ are analyzed. Their difference indicates that the alignment of fragments is higher in ternary fission than in binary one. The consequences of possible relation between the mechanism of ternary fission and the excitation of collecti

A. Ballesteros, Enrico Celeghini, F. J. Herranz, M. A. del Olmo

A universal R--matrix for the quantum Heisenberg algebra h(1)q is presented. Despite of the non--quasitriangularity of this Hopf algebra, the quantum group induced from it coincides with the quasitriangular deformation already known.

A. Mezhlumian, A. Peet, L. Thorlacius

Susskind has recently shown that a relativistic string approaching the event horizon of a black hole spreads in both the transverse and longitudinal directions in the reference frame of an outside observer. The transverse spreading can be described as a branching diffusion of wee string bits. This stochastic process provides a mechanism for thermalizing the

Marcelo R. Ubriaco

We develop the basic formalism of complex $q$-analysis to study the solutions of second order $q$-difference equations which reduce, in the $q\rightarrow 1$ limit, to the ordinary Laplace equation in Euclidean and Minkowski space. After defining an inner product on the function space we construct and study the properties of the solutions, and then apply this

V. G. Ksenzov

The vacuum energy density is obtained for the $O(N)$ nonlinear sigma model. It is shown that non-perturbative contributions are connected with the square of the symmetry current of the group $O(N)$. This result is valid for $σ$- fields which are subject to the constraint.

Dimitris Kominis

We examine the phenomenology of the $CP$-odd scalar $A^0$ of two-Higgs-doublet models. We explore the parameter space determined by triviality bounds and identify the regions where the $A^0$ can be detected at the LHC in each of the following modes: the inclusive two-photon decay mode, the $l^{\pm}γγX$ mode from $t\overline{t}A^0$ production and the $A^0\rig

Sergio Mendoza, Jack Smith

We present results for total cross sections, single and double differential distributions and correlations between pairs of outgoing particles in the reactions p + antip --> W^+ + photon and p + antip --> W^+ + photon + jet at sqrt(S)=1.8 TeV. Order alpha-strong QCD corrections and leading logarithm photon bremsstrahlung contributions are included in the MS-

G. Ecker

The leading divergences of the generating functional for Green functions of quark currents between one--nucleon states are calculated with heat kernel techniques. The results allow for a chiral invariant renormalization of all two--nucleon Green functions of the pion--nucleon system to $O(p^3)$ in the low--energy expansion.

Larry McLerran, Raju Venugopalan

We compute the Green's functions for scalars, fermions and vectors in the color field associated with the infinite momentum frame wavefunction of a large nucleus. Expectation values of this wavefunction can be computed by integrating over random orientations of the valence quark charge density. This relates the Green's functions to correlation functi

R. Basu, A. Vilenkin

Topological defects can be formed during inflation by phase transitions as well as by quantum nucleation. We study the effect of the expansion of the Universe on the internal structure of the defects. We look for stationary solutions to the field equations, i.e. solutions that depend only on the proper distance from the defect core. In the case of very thin

Richard H. Price, Jorge Pullin

The problem of the mutual attraction and joining of two black holes is of importance as both a source of gravitational waves and as a testbed of numerical relativity. If the holes start out close enough that they are initially surrounded by a common horizon, the problem can be viewed as a perturbation of a single black hole. We take initial data due to Misne

J. A. Nieto, O. Obregón, J. Socorro

By adding the Pontrjagin topological invariant to the gauge theory of the de Sitter group proposed by MacDowell and Mansouri we obtain an action quadratic in the field-strengths, of the Chern-Simons type, from which the Ashtekar formulation is derived.

A. V. Chubukov, K. A. Musaelian

The 2D Hubbard model is extended by placing 2S orbitals at each lattice site and studied in a systematic 1/S expansion. The 1/S results for the magnetic susceptibility and the spectra of spin-wave excitations at half-filling are consistent with the large S calculations for the Heisenberg antiferromagnet. The 1/S corrections to the fermionic spectrum lift the

Nicolas Brunel, Riccardo Zecchina

In the context of attractor neural networks, we study how the equilibrium analog neural activities, reached by the network dynamics during memory retrieval, may improve storage performance by reducing the interferences between the recalled pattern and the other stored ones. We determine a simple dynamics that stabilizes network states which are highly correl

C. Zhou, H. J. Schulz

We study the dynamics of a single hole in an otherwise half--filled two--dimensional Hubbard model by introducing a nonlocal Bogolyubov transformation in the antiferromagnetic state. This allows us to rewrite the Hamiltonian in a form that makes a separation between high--energy processes (involving double--occupancy) and low--energy physics possible. A diag

Andrew Gould, Jens Villumsen

Weak gravitational lensing due to nearby structures, such as the Coma cluster, and the Local Supercluster can be expected to polarize images of distant galaxies by ${\cal O}(0.2%Ω)$ with coherence over scales of tens of square degrees. The Sloan Survey, which will image $\gsim 10^4$ galaxies $\rm deg^{-2}$ over $π$ steradians, should be sensitive to polariza

E. Hofstetter, M. Schreiber

A general method to describe a second-order phase transition is discussed. It starts from the energy level statistics and uses of finite-size scaling. It is applied to the metal-insulator transition (MIT) in the Anderson model of localization, evaluating the cumulative level-spacing distribution as well as the Dyson-Metha statistics. The critical disorder $W

B. Dammann, H. C. Fogedby, J. H. Ipsen, C. Jeppesen

We study the conformation and scaling properties of a self-avoiding fluid membrane, subject to an osmotic pressure $p$, by means of Monte Carlo simulations. Using finite size scaling methods in combination with a histogram reweighting techniques we find that the surface undergoes an abrupt conformational transition at a critical pressure $p^\ast$, from low p

Song He, Steven H. Simon, Bertrand I. Halperin

We study the excitation spectra and the dynamical structure factor of quantum Hall states in a finite size system through exact diagonalization. Comparison is made between the numerical results so obtained and the analytic results obtained from a modified RPA in the preceding companion paper. We find good agreement between the results at low energies.

Steven H. Simon, Bertrand I. Halperin

Using a well known singular gauge transformation, certain fractional quantized Hall states can be modeled as integer quantized Hall states of transformed fermions interacting with a Chern-Simons field. In previous work we have calculated the electromagnetic response function of these states at arbitrary frequency and wavevector by using the Random Phase Appr

L. Biferale, A. Lambert, R. Lima, G. Paladin

We study a shell model for the energy cascade in three dimensional turbulence at varying the coefficients of the non-linear terms in such a way that the fundamental symmetries of Navier-Stokes are conserved. When a control parameter $ε$ related to the strength of backward energy transfer is enough small, the dynamical system has a stable fixed point correspo

E. R. Seaquist, R. J. Ivison

Recent maser surveys have shown that many potential OH/IR stars have no OH masers in their circumstellar envelopes, despite the modest requirements which should be implicitly met by IRAS colour-selected candidates. It has been suggested that these OH/IR colour mimics must have a degenerate companion which dissociates OH molecules and disrupts the masing acti

R. J. Ivison, E. R. Seaquist, P. J. Hall

We present the first results from an all-sky maser-line survey of symbiotic Miras. Interferometric spectral-line observations of R Aqr and H1-36 Arae have revealed a 22-GHz water maser in the former and 1612-MHz hydroxyl and weak 22-GHz water maser emission from the latter. H1-36 has thus become the first known symbiotic OH/IR star. We have also detected wea

Huib Jan van Langevelde, Ewine F. van Dishoeck, Geoffrey A. Blake

High spectral and spatial resolution observations of the HCO+ molecule toward the T Tau binary system obtained with the Owens Valley Millimeter Array reveal a broad emission line profile (V_LSR = 7.2 km/s, width = 2.0 km/s) upon which a narrow, redshifted absorption feature (V_LSR = 8.5 km/s, width +/- 0.5 km/s) is superposed. One possible interpretation of

Yuri S. Kivshar, Niels Grønbech-Jensen, Robert D. Parmentier

Dynamics of sine-Gordon kinks in the presence of rapidly varying periodic perturbations of different physical origins is described analytically and numerically. The analytical approach is based on asymptotic expansions, and it allows to derive, in a rigorous way, an effective nonlinear equation for the slowly varying field component in any order of the asymp

Alex Pomarol

We derive the one-loop effective action induced by a heavy top in models with an extended Higgs sector. We use the effective action to analyze the top corrections to the $ρ$ parameter and to the Higgs-gauge boson couplings. We show that in models with $ρ\not=1$ at tree-level, one does not lose generally the bound on $m_t$ from the $ρ$ parameter.

Scott Dodelson, Arthur Kosowsky, Steven T. Myers

Many analyses of microwave background experiments neglect the correlation of noise in different frequency or polarization channels. We show that these correlations, should they be present, can lead to severe misinterpretation of an experiment. In particular, correlated noise arising from either electronics or atmosphere may mimic a cosmic signal. We quantify

Mans Henningson

We study the $N = 2$ coset models in their formulation as supersymmetric gauged Wess-Zumino-Witten models. A model based on the coset $G/H$ is invariant under a symmetry group isomorphic to $\Z_{k+Q}$, where $k$ is the level of the model and $Q$ is the dual Coxeter number of $G$. Using a duality-like relationship, we show that the $\Z_m$ orbifold of the vect

C. Grosche, G. S. Pogosyan, A. N. Sissakian

Path integral formulations for the Smorodinsky-Winternitz potentials in two- and three-dimen\-sional Euclidean space are presented. We mention all coordinate systems which separate the Smorodinsky-Winternitz potentials and state the corresponding path integral formulations. Whereas in many coordinate systems an explicit path integral formulation is not possi

C. Klimcik, A. A. Tseytlin

We construct a new class of exact string solutions with a four dimensional target space metric of signature ($-,+,+,+$) by gauging the independent left and right nilpotent subgroups with `null' generators of WZNW models for rank 2 non-compact groups $G$. The `null' property of the generators (${\rm Tr }(N_n N_m)=0$) implies the consistency of the gau

A. Ioannissyan, J. W. F. Valle

This version corrects the first one in eq.3.4 and table 1 where there was a bar missing in the 126 representation. All other equations and results are unchanged and correct. However, the criticism we had made in the earlier version to the work of Caldwell and Mohapatra was not correct and has been removed from the "note added" where it appeared. More

Fiorenzo Bastianelli, Nobuyoshi Ohta

We review the detailed structure of the large $N=4$ superconformal algebra, and construct its BRST operator which constitutes the main object for analyzing $N=4$ strings. We then derive the general condition for the nilpotency of the BRST operator and show that there exists a line of critical $N=4$ string theories.

Chanju Kim

Using Wilson-Polchinski renormalization group equations, we give a simple new proof of decoupling in a $ϕ^4$-type scalar field theory involving two real scalar fields (one is heavy with mass $M$ and the other light). Then, to all orders in perturbation theory, it is shown that effects of virtual heavy particles up to the order $1/M^{2N_0}$ can be systematica

L. Marleau

We review the different approaches used to treat the photon structure function. We suggest that despite some uncertainties it should remain sensitive to $Λ.$

B. Dion, L. Marleau

We generalize the approach of Atiyah and Manton for generating Skyrmion configurations from instantons. The result is a series which parameters are found directly from the chiral angle equation. The series converge rapidly to the exact solution for a class of the Skyrme-like models (including the Skyrme model itself) but describe with less accuracy other typ

C. Kiefer, H. D. Zeh

We show that the Wheeler-DeWitt equation with a consistent boundary condition is only compatible with an arrow of time that formally reverses in a recollapsing universe. Consistency of these opposite arrows is facilitated by quantum effects in the region of the classical turning point. Since gravitational time dilation diverges at horizons, collapsing matter

L. Bergstrom, P. Ernstrom

We calculate next to leading order QCD corrections to the direct decays b -> J/Psi + X and b -> eta_c + X. The strong renormalization scale dependence is seen to persist also in this order and in fact the rate is driven to an unphysical negative value at the M_b scale. We show that this is a consequence of the strong suppression and scale dependence in the l

E. B. Balbutsev, A. V. Unzhakova, M. V. Andres, F. Catara

An analysis of the real and imaginary part of the polarization potential in terms of the relative contributions of the single collective states for the $ ^{208}Pb + ^{208}Pb $ system has been done. The polarization potential has been calculated within the Feshbach formalism taking into account the collective states calculated with the Wigner function moments

Alvaro Arias

In this paper we prove that several operator algebras are completely isomorphic to each other; e.g., the $C^*_λ(F_k)$, $k\geq 2$, the $C^*$-algebras generated by the regular left representation $λ:F_k\to B(\ell_2(F_k))$, are completely isomorphic to each other. We also study the ``non-commutative'' analytic spaces introduced by G. Popescu [Po], and g

Brian R. Greene, David R. Morrison, M. Ronen Plesser

We describe mirror manifolds in dimensions different from the familiar case of complex threefolds. We emphasize the simplifying features of dimension three and supply more robust methods that do not rely on such special characteristics and hence naturally generalize to other dimensions. The moduli spaces for Calabi--Yau $d$-folds are somewhat different from

Mu-Lin Yan, Xing-He Meng

The corrections to the Gell-Mann-Okubo relations of baryon-masses are presented in the SU(3) Skyrme model. These corrections are calculated up to the second order in flavor breaking at the skyrmion quantum mechanics. The results are compatible with the experimental data. They could be regarded as a signal of existence of some obscure SU(3)-multiplets: 27-let

V. B. Semikoz, J. W. F. Valle

We consider active-sterile neutrino conversions in the early universe hot plasma in the presence of a random magnetic field generated at the electroweak phase transition. Within a random field domain the magnetization asymmetry of the lepton antilepton plasma produced by a uniform constant magnetic field is huge in contrast to their small density asymmetry,

Sergio Mendoza, Jack Smith

We present a detailed computation of the fully exclusive cross section of p + antip --> W + photon + X with X = 0 and 1 jet in the framework of the factorization theorem and dimensional regularization. Order alpha-strong and photon bremsstrahlung contributions are discussed in the MS-bar mass factorization scheme. The resulting expressions are ready to be im

K Golec-Biernat

We make a critical, next-to-leading order, study of the accuracy of the Prytz relation, which is frequently used to extract the gluon distribution at small $x$ from the logarithmic slopes of the structure function $F_{2}$. We find that the simple relation is not generally valid in the Hera regime, but show that it is a reasonable approximation for gluons whi

Kiwoon Choi

It is well known that supersymmetric models allow new sources for CP violation that arise from soft supersymmetry breaking terms. If unsuppressed, these new CP-violating phases would give too large a neutron electric dipole moment. We discuss a mechanism for suppressing SUSY phases in string-inspired supergravity models in which supersymmetry is assumed to b

A. Czarnecki, M. Jeżabek

Analytic formulae are given for QCD corrections to the lepton spectra in decays of polarised up and down type heavy quarks. These formulae are much simpler than the published ones for the corrections to the spectra of charged leptons originating from the decays of unpolarised quarks and polarised up type quarks. Distributions of leptons in semileptonic $Λ_c$

Seyong Kim, Aleksandar Kocic, John Kogut

We study the problem of triviality in the four dimensional Nambu-Jona-Lasinio model with discrete chiral symmetry using both large-N expansions and lattice simulations. We find that logarithmic corrections to scaling appear in the equation of state as predicted by the large-N expansion. The data from $16^4$ lattice simulations is sufficiently accurate to dis

Daniel H. Gottlieb

Given any space-time $M$ without singularities and any event $O$, there is a natural continuous mapping $f$ of a two dimensional sphere into any space-like slice $T$ not containing $O$. The set of future null geodesics (or the set of past null geodesics) forms a 2-sphere $S^2$ and the map $f$ sends a point in $S^2$ to the point in $T$ which is the intersecti

G. 't Hooft

The $S$-matrix Ansatz for the construction of a quantum theory of black holes is further exploited. We first note that treating the metric tensor $g_{\m\n}$ as an operator rather than a background allows us to use a setting where information is not lost. But then we also observe that the 'trans-Planckian' particles (particles with kinetic energies be

Yi Cheng, Mu-Lin Yan, Bao-Heng Zhao

The quantum 2-component DS1 system was reduced to two 1D many-body problems with $δ-$function interactions, which were solved by Bethe ansatz. Using the ansatz in ref.[1] and introducing symmetric and antisymmetric Young operators of the permutation group, we obtain the exact solutions for the system.

F. Laloe

Using Ursell operators for the study of the poperties of dilute degenerate gases

I. V. Kolokolov Budker

Starting from the Abrikosov-Ryzhkin formulation of the 1D random potential problem I find closed functional representations for various physical quantities. These functional integrals are calculated exactly without the use of any perturbative expansions. The expressions for the multipoint densities correlators are obtained. Then I evaluate the mean square di

M. J. Martins

We have studied the massive parafermionic sector of an integrable spin-$s$ chain with an impurity of spin-$s^{'}$ in presence of a magnetic field. The effect of the impurity is encoded in a computable parafermionic impurity scattering amplitude and its contribution to the finite size properties of the free energy is discussed. As an example we compute th

R. A. Richardson, Franco Nori

The concept of exchange length is used to determine the effects of boundary scattering on transport in samples of circular and rectangular cross section. Analytical expressions are presented for an effective mean-free path for transport in the axial direction. The relationship to the phonon thermal conductivity is discussed. (This letter outlines the results

R. Richardson, Franco Nori

We utilize a geometric argument to determine the effects of boundary scattering on the carrier mean-free path in samples of various cross sections. Analytic expressions for samples with rectangular and circular cross sections are obtained. We also outline a method for incorporating these results into calculations of the thermal conductivity.

Britton Plourde, Franco Nori, Michael Bretz

We analyze the statistics of water droplet avalanches in a continuously driven system. Distributions are obtained for avalanche size, lifetime, and time between successive avalanches, along with power spectra and return maps. For low flow rates and different water viscosities, we observe a power-law scaling in the size and lifetime distributions of water dro

Norihiko Nishiguchi, Shin-ichiro Tamura, Franco Nori

We study both analytically and numerically phonon transmission fluctuations and localization in partially ordered superlattices with correlations among neighboring layers. In order to generate a sequence of layers with a varying degree of order we employ a model proposed by Hendricks and Teller as well as partially ordered versions of deterministic aperiodic

Norihiko Nishiguchi, Shin-ichiro Tamura, Franco Nori

We analytically study phonon transmission and localization in random superlattices by using a Green's function approach. We derive expressions for the average transmission rate and localization length, or Lyapunov exponent, in terms of the superlattice structure factor. This is done by considering the backscattering of phonons, due to the complex mass de

Zugan Deng, Xiaoyang Xia, Li-Zhi Fang

We present results of searching for the possible typical scales in the spatial distribution of QSOs. Our method is based on the second derivative of the two-point correlation function. This statistic is sensitive to the scale of the maximum in the spectrum $P(k)$ of the density perturbation in the universe. This maximum or bend scale can be detected as the w

Roberto Turolla, Luca Zampieri, Monica Colpi, Aldo Treves

Stationary, spherical accretion onto an unmagnetized neutron star is here reconsidered on the wake of the seminal paper by Zel'dovich \& Shakura (1969). It is found that new ``hot'' solutions may exist for a wide range of luminosities. These solutions are characterized by a high temperature, $10^{9}÷10^{11}$ K, and arise from a stationary equilib

Matthias Steinmetz

We present numerical simulations of galaxy formation, one of the most challenging problems in computational astrophysics. The key point in such simulations is the efficient solution of the N--body problem. If the gas of a galaxy is treated by means of smoothed particle hydrodynamics (SPH), the hydrodynamic equations can be reduced to a form similar to that o

Ian Smail, Richard S. Ellis, Michael J. Fitchett, Alastair C. Edge

Using a non-parametric procedure developed by Kaiser \& Squires (1993), we analyse the statistical image distortions of faint field galaxies to $I\ls25.5$ in two distant X-ray luminous clusters 1455+22 ($z_{cl}=0.26$) and 0016+16 ($z_{cl}=0.55$) to derive two dimensional projected mass distributions for the clusters. The mass maps of 1455+22 and 0016+16 are

Ian Smail, Richard S. Ellis, Michael J. Fitchett

{}From deep optical images of three clusters selected by virtue of their X-ray luminosity and/or optical richness (1455+22; $z=0.26$, 0016+16; $z=0.55$ and 1603+43; $z=0.89$), we construct statistically-complete samples of faint field galaxies ($I \leq 25$) suitable for probing the effects of gravitational lensing. By selecting clusters across a wide redshif

A. Ballesteros, F. J. Herranz, M. A. del Olmo, M. Santander

The N-dimensional Cayley-Klein scheme allows the simultaneous description of $3^N$ geometries (symmetric orthogonal homogeneous spaces) by means of a set of Lie algebras depending on $N$ real parameters. We present here a quantum deformation of the Lie algebras generating the groups of motion of the two and three dimensional Cayley-Klein geometries. This def

Andrei Linde, Dmitri Linde

We investigate the global structure of inflationary universe both by analytical methods and by computer simulations of stochastic processes in the early Universe. We show that the global structure of the universe depends crucially on the mechanism of inflation. In the simplest models of chaotic inflation the Universe looks like a sea of thermalized phase sur

N. N. Nikolaev, B. G. Zakharov, V. R. Zoller

The $S$-matrix of diffractive scattering is diagonalized in terms of the colour dipole-dipole cross section. Recently, we have shown that the dipole cross section satisfies the generalized BFKL equation. In this paper we discuss the spectrum and solutions of our generalized BFKL equation with allowance for the finite gluon correlation radius $R_{c}$. The lat

Theodore W. Burkhardt, H. W. Diehl

With simple, exact arguments we show that the surface magnetization $m_1$ at the extraordinary and normal transitions and the surface energy density $ε_1$ at the ordinary, extraordinary, and normal transitions of semi-infinite $d$-dimensional Ising systems have leading thermal singularities $B_\pm |t|^{2-α}$, with the same critical exponent and amplitude rat

Harry N. Nelson

We present preliminary results from the CLEO-II collaboration on a variety of hadronic final states of mesons containing heavy quarks. In particular, the pattern of 2-body \B\ decays is now decisively different that that of \D\ and \K\ decays; perhaps a consequence will be that $τ_{\BM}<τ_{\BZB}$. We have observed `wrong-sign&#39; $\DZ\sto\KP\PIM$ decays, wh

Maximilian Kreuzer

Calculating the (a,c) ring of the maximal phase orbifold for `invertible&#39; Landau--Ginzburg models, we show that the Berglund--H&#34;ubsch construction works for all potentials of the relevant type. The map that sends a monomial in the original model to a twisted state in the orbifold representation of the mirror is constructed explicitly. Via this map, t

S. Kumano

Q$^2$ variation of the nuclear-structure-function ratio $F_2^A(x,Q^2)/F_2^D(x,Q^2)$ is investigated in a parton model with Q$^2$-rescaling and parton-recombination effects. Calculated results are compared with the NMC (New Muon Collaboration) and the Fermilab-E665 experimental data. We find that our theoretical results show small Q$^2$ variations and that th

Alexander V. Evako

In this paper we develop some combinatorial models for continuous spaces. In this spirit we study the approximations of continuous spaces by graphs, molecular spaces and coordinate matrices. We define the dimension on a discrete space by means of axioms, and the axioms are based on an obvious geometrical background. This work presents some discrete models of

Maria de Sousa Vieira, Hans J. Herrmann

We introduce a simple model for DNA evolution. Using the method of Peng et al.$^1$, we investigate the fractal properties of the system. For small chains and chains of intermediate size we find a fractal exponent that indicates the existence of long-range correlations, as in real DNA sequences. However, when very large chains are studied the fractal exponent

D. D. Dixon, M. Zak, J. P. Zbilut

A method for detecting possible non-deterministic dynamics underlying a time series is introduced. Non-deterministic dynamics may arise due to the failure of the Lipschitz condition in the equations of motion. At a singular point, the phase space trajectory of the system may jump from one solution to another. This discontinous change implies divergence of th

David Raitt, Hermann Riecke

In pattern-forming systems, competition between patterns with different wave numbers can lead to domain structures, which consist of regions with differing wave numbers separated by domain walls. For domain structures well above threshold we employ the appropriate phase equation and obtain detailed qualitative agreement with recent experiments. Close to thre

Curtis G. Callan, Igor R. Klebanov, Andreas W. W. Ludwig, Juan M. Maldacena

We study the conformal field theory of a free massless scalar field living on the half line with interactions introduced via a periodic potential at the boundary. An SU(2) current algebra underlies this system and the interacting boundary state is given by a global SU(2) rotation of the left-moving fields in the zero-potential (Neumann) boundary state. As th

Pol Vanhaecke

We show how there is associated to each non-constant polynomial $F(x,y)$ a completely integrable system with polynomial invariants on $\Rd$ and on $\C{2d}$ for each $d\geq1$; in fact the invariants are not only in involution for one Poisson bracket, but for a large class of polynomial Poisson brackets, indexed by the family of polynomials in two variables. W

P V Landshoff, J C Taylor

We discuss the bremsstrahlung of photons into a heat bath, and calculate from first principles the energy radiated. Even to lowest order the spectrum of the radiation at low frequency is no more singular than at zero temperature. In addition to the obvious contributions, this spectrum includes terms associated with fluctuations. [Revised version has addition

Yigal Shamir

It is proposed that gravity may arise in the low energy limit of a model of matter fields defined on a special kind of a dynamical random lattice. Time is discretized into regular intervals, whereas the discretization of space is random and dynamical. A triangulation is associated to each distribution of the spacetime points using the flat metric of the embe

Stefan Cordes, Gregory Moore, Sanjaye Ramgoolam

We describe a topological string theory which reproduces many aspects of the 1/N expansion of SU(N) Yang-Mills theory in two spacetime dimensions in the zero coupling (A=0) limit. The string theory is a modified version of topological gravity coupled to a topological sigma model with spacetime as target. The derivation of the string theory relies on a new in

Peter Bueken

Generalizing a construction of P. Vanhaecke, we introduce a large class of degenerate (i.e., associated to a degenerate Poisson bracket) completely integrable systems on (a dense subset of) the space $\R^{2d+n+1}$, called the generalized master systems. It turns out that certain generalized master systems (with different Poisson brackets and different Hamilt

J Hoppe

Various reductions, and soime solutions of the classical equations of motion of a relativistic membrane are given

V. B. Kuznetsov, A. V. Tsiganov

We consider quantum analogs of the relativistic Toda lattices and give new $2\times 2$ $L$-operators for these models. Making use of the variable separation the spectral problem for the quantum integrals of motion is reduced to solving one-dimensional separation equations.

Christian Grosche

$δ&#39;$-function perturbations and Neumann boundary conditions are incorporated into the path integral formalism. The starting point is the consideration of the path integral representation for the one dimensional Dirac particle together with a relativistic point interaction. The non-relativistic limit yields either a usual $δ$-function or a $δ&#39;$-functi

T. Fujiwara, Y. Igarashi, M. Koseki, R. Kuriki

Based on the extended BRST formalism of Batalin, Fradkin and Vilkovisky, we perform a general algebraic analysis of the BRST anomalies in superstring theory of Neveu-Schwarz-Ramond. Consistency conditions on the BRST anomalies are completely solved. The genuine super-Virasoro anomaly is identified with the essentially unique solution to the consistency condi

Biswajoy Brahmachari, Manoj. K. Samal, Utpal Sarkar

We study the Higgs potentials in the Left-Right symmetric model for various choices of Higgs fields. We give emphasis to the cases when the Higgs field $ξ=(2,2,15)$ is included to give the correct relations of quark masses and a singlet field $η$ which breaks the left-right parity. As special cases we also include $ξ^\prime=(2,2,15)$ and $χ=(2,2,6)$ (which a

Thomas Appelquist, John Terning, L. C. R. Wijewardhana

We investigate the chiral phase transition in 2+1 dimensional QED. Previous gap equation and lattice Monte-Carlo studies of symmetry breaking have found that symmetry breaking ceases to occur when the number of fermion flavors exceeds a critical value. Here we focus on the order of the transition. We find that there are no light scalar degrees of freedom pre

B. Holdom, Randy Lewis

We discuss the running couplings in the standard model, SU(3$)_C \times $SU(2$)_L \times $U(1$)_Y$, when the Higgs sector is replaced by SU($N_{TC})$ technicolor. Particular attention is given to the running of the couplings at momentum scales where technicolor is nonperturbative, and in this region we apply a relativistic constituent technifermion model. Th