September 1995 arXiv papers — page 5

Iwan Jensen, Anthony J. Guttmann

We have derived long series expansions of the percolation probability for site and bond percolation on directed square and honeycomb lattices. For the square bond problem we have extended the series from 41 terms to 54, for the square site problem from 16 terms to 37, and for the honeycomb bond problem from 13 terms to 36. Analysis of the series clearly show

Baowen Li, Marko Robnik

In numerically solving the Helmholtz equation inside a connected plane domain with Dirichlet boundary conditions (the problem of the quantum billiard) one surprisingly faces enormous difficulties if the domain has a problematic geometry such as various nonconvex shapes. We have tested several general numerical methods in solving the quantum billiards. Follow

James F. Babb

The nuclear spin--rotation interaction in the hyperfine structure of the hydrogen molecular ion is investigated. The interaction constants are determined and are found to differ in sign and magnitude compared to another theory, but they are in agreement with some values derived from experiment.

Jablonka, Bica, Pelat, Alloin

We have carried out spectrophotometry in the range 3600--9700Å~ of five globular clusters in NGC 5128 for which previous photometric studies suggested a high metal content. We compare the equivalent widths of a set of metallic features of the NGC 5128 clusters with those of well-studied Galactic and M31 globular clusters. This enables us to derive a reliable

W. Pych, A. Olech

We report a CCD optical photometry of a dwarf nova AL Com in superoutburst. Before superhumps occurred the light curve was highly variable with dominant periods about 41 minutes and 81.5 minutes for different nights. The period of observed superhumps is 82.5 minutes and seems to be stable. The first harmonic of the basic period is also present. We detected a

Th. A. Rijken, V. G. J. Stoks

Two-meson-exchange nucleon-nucleon potentials are derived where either one or both nucleons contains a pair vertex. Physically, the meson-pair vertices are meant to describe in an effective way (part of) the effects of heavy-meson exchange and meson-nucleon resonances. {}From the point of view of ``duality,'' these two kinds of contribution are rough

Th. A. Rijken, V. G. J. Stoks

Pion-meson-exchange nucleon-nucleon potentials are derived for two nucleons in the intermediate states. The mesons we include are (i) pseudoscalar mesons: $π, η, η'$; (ii) vector mesons: $ρ, ω, ϕ$; (iii) scalar mesons: $a_{0}(980), \varepsilon(760), f_{0}(975)$; and (iv) the $J=0$ contribution from the Pomeron. Strong dynamical pair suppression is assume

J. D. F. Franklin, I. Zailer, C. J. B. Ford, P. J. Simpson

We have investigated experimentally resonant tunnelling through single-particle states formed around an antidot by a magnetic field, in the fractional quantum Hall regime. For 1/3 filling factor around the antidot, Aharonov-Bohm oscillations are observed with the same magnetic field period as in the integer quantum Hall regime. All our measurements are consi

P. J. Forrester, B. Jancovici

An exact solution is given for a two-dimensional model of a Coulomb gas, more general than the previously solved ones. The system is made of a uniformly charged background, positive particles, and negative particles, on the surface of a sphere. At the special value $Γ= 2$ of the reduced inverse temperature, the classical equilibrium statistical mechanics is

Andrzej J. Buras

We review several aspects of B-Physics. In particular we discuss: i) The theoretical framework for B-decays, ii) Weak decays beyond leading logarithms, iii) Standard analysis of the unitarity triangle, iv) Rare B-decays, v) CP violation including the issue of electroweak penguins vi) Future visions of this field.

Ian I. Kogan, Ariel R. Zhitnitsky

We analyse the highly excited states in $QCD_2 (N_{c}\rightarrow\infty) $ with adjoint matter by using such general methods as dispersion relations, duality and unitarity. We find the Hagedorn-like spectrum $ρ(m) \sim m^{-a}\exp(β_H m)$ where parameters $β_H$ and $a$ can be expressed in terms of asymptotics of the following matrix elements $f_{n_{\{k\}}} \si

M. Daumer

Quantum mechanical scattering theory is a subject with a long and winding history. We shall pick out some of the most important concepts and ideas of scattering theory and look at them from the perspective of Bohmian mechanics: Bohmian mechanics, having real particle trajectories, provides an excellent basis for analyzing scattering phenomena.

E. Buffenoir

A new approach to the quantization of Chern-Simons theory has been developed in recent papers of the author. It uses a "simulation" of the moduli space of flat connections modulo the gauge group which reveals to be related to a lattice gauge theory based on a quantum group. After a generalization of the formalism of q-deformed gauge theory to the cas

M. R. Frank, B. K. Jennings, G. A. Miller

The influence of the nuclear medium upon the internal structure of a composite nucleon is examined. The interaction with the medium is assumed to depend on the relative distances between the quarks in the nucleon consistent with the notion of color neutrality, and to be proportional to the nucleon density. In the resulting description the nucleon in matter i

Paul G. A. Floris, Erik Koelink

Starting from the addition formula for $q$-disk polynomials, which is an identity in non-commuting variables, we establish a basic analogue in commuting variables of the addition and product formula for disk polynomials. These contain as limiting cases the addition and product formula for little $q$-Legendre polynomials. As $q$ tends to $1$ the addition and

R. Banerjee

A functional integral approach is developed to discuss the bosonisation of the massive Thirring and the massive Schwinger models in arbitrary D-dimensions. It is found that these models, to {\it all} orders in the inverse fermi mass, bosonise to a theory involving a usual gauge field and a (D-2) rank antisymmetric (Kalb-Ramond) tensor field. Explicit bosonis

Klaus Behrndt, Renata Kallosh

We present a static multi-center magnetic solution of toroidally compactified heterotic string theory, which is T-duality covariant. The space-time geometry depends on the mass M and on the O(6,22)-norm N of the magnetic charges. For different range of parameters (M,N)-solution includes 1) two independent positive parameters extremal magnetic black holes wit

T. Schaefer, E. V. Shuryak

In this paper we study the statistical mechanics of the instanton liquid in QCD. After introducing the partition function as well as the gauge field and quark induced interactions between instantons we describe a method to calculate the free energy of the instanton system. We use this method to determine the equilibrium density and the equation of state from

Michael H. Holzscheiter, T. Goldman, Michael Martin Nieto

Certain modern theories of gravity predict that antimatter will fall differently than matter in the Earth's gravitational field. However, no experimental tests of gravity on antimatter exist and all conclusions drawn from experiments on matter depend, at some level, on a specific model. We have proposed a direct measurement that would compare the gravita

O. G. Miranda, M. Maya, R. Huerta

In a previous paper we study the neutrino-electron scattering in the framework of a left-right symmetric model (LRSM). Constraints on the LRSM parameters $M_{Z_{2}}$ and $ϕ$ were obtained. Based on new measurements we present an update to these constraints and also include in the calculation the radiative corrections.

J. Polonyi

Some features of the high temperature gluonic matter, such as the breakdown of the fundamental group symmetry by the kinetic energy, the screening of test quarks by some unusual gluon states and the explanation of the absence of isolated quarks in the vacuum without the help of infinities are presented in this talk. Special attention is paid to separate the

Enke Wang, Ulrich Heinz

We study the 2-loop resummed propagator in hot $g^2ϕ^4$ theory. The propagator has a cut along the whole real axis in the complex energy plane, but for small $g$, the spectral density is sharply peaked around the plasmon. The dispersion relation and the width of the plasmon are calculated at zero {\em and} finite momentum. At large momenta the spectral width

D. Tadi\' c, S. Žganec

A fairly general Lorentz-covariant quark model of mesons is constructed. It has several versions whose nonrelativistic limit corresponds to the well-known Isgur, Scora, Grinstein, and Wise model. In the heavy-quark limit, the covariant model naturally and automatically produces the heavy-quark symmetry results for meson decay constants and semileptonic decay

Enke Wang, Xiaofei Zhang, Ulrich Heinz

We derive a spectral representation for the two-point Green function for arbitrary composite field operators in Thermo Field Dynamics (TFD). A simple way for calculating the spectral density within TFD is pointed out and compared with known results from the imaginary time formalism. The method is applied to hot $ϕ^4$ theory. We give a compact derivation of t

K. Tesima

The multiple hadroproduction in the perturbative QCD is briefly reviewed. There are a number of quantities which can be analysed with the use of the high-luminosity TRISTAN data. The analysis will contribute to clarifying some unsolved questions, and to the deeper understanding of the jet physics.

Richard Wittmann, Ulrich Heinz

We study the structure of antiproton spectra at extreme subthreshold bombarding energies using a thermodynamic picture. Antiproton production processes and final state interactions are discussed in detail in order to find out what can be learned about these processes from the observed spectra.

R. Foot, M. J. Thomson, R. R. Volkas

We re-examine neutrino oscillations in the early universe. Contrary to previous studies, we show that large neutrino asymmetries can arise due to oscillations between ordinary neutrinos and sterile neutrinos. This means that the Big Bang Nucleosynthesis (BBN) bounds on the mass and mixing of ordinary neutrinos with sterile neutrinos can be evaded. Also, it i

Wolfhard Janke, Ramon Villanova

We study the effect of quenched coordination-number disorder of random lattices on the nature of the phase transition in the two-dimensional eight-state Potts model, which is of first order on regular lattices. We consider Poissonian random lattices of toroidal topology constructed according to the Voronoi/Delaunay prescription. Monte Carlo simulations yield

S. Collins, U. M. Heller, J. Sloan, J. Shigemitsu

We present {\it preliminary} results for the decay constants of heavy-light mesons using NRQCD heavy and tadpole improved Clover light quarks. A comparison is made with data obtained using Wilson light quarks. We present an analysis of the 1/M corrections to the decay constants in the static limit and compare with the predictions of HQET.

Philippe de Forcrand, Margarita Garcia Perez, Ion-Olimpiu Stamatescu

We propose and study a ``gold-washing" - type of algorithm which smooths out the short range fluctuations but leaves invariant instantons above a certain size. The algorithm needs no monitoring or calibration.

P. Sawicki, J. Wosiek

Some modifications of the Luscher algorithm, which reduce the autocorelation time, are proposed and tested.

D. Espriu, A. Travesset

Motivated by the successful application of MCRG in momentum space to $λϕ^4_3$ we determine the critical exponents at the crumpling transition in fixed triangulated surfaces. The results are still tentative, but suggest that $-1.0\ge η\ge -1.3$, pointing at a value for the fractal Hausdorff dimension at the crumpling transistion fixed point somewhere between

Piljin Yi

The main topic of this talk is the Hawking effect when the black holes in question are undergoing a uniform acceleration. The semiclassical effect of the acceleration is most striking when the Hawking temperature equals the acceleration temperature. Within the usual late-time approximation, the natural black hole vacuum is then equivalent to the asymptotical

Gilbert Weinstein

The Einstein/Abelian-Yang-Mills Equations reduce in the stationary and axially symmetric case to a harmonic map with prescribed singularities $\p\colon\R^3\smΣ\to\H^{k+1}_\C$ into the $(k+1)$-dimensional complex hyperbolic space. In this paper, we prove the existence and uniqueness of harmonic maps with prescribed singularities $\p\colon\R^n\smΣ\to\H$, where

Charles A. Stafford, Ned S. Wingreen

The time average of the fully nonlinear current through a double quantum dot, subject to an arbitrary combination of ac and dc voltages, is calculated exactly using the Keldysh nonequilibrium Green function technique. When driven on resonance, the system functions as an efficient electron pump due to Rabi oscillation between the dots. The pumping current is

Dong-Zi Liu, K. Levin

We demonstrate that a $d_{x^2-y^2}$ superconducting pairing is naturally associated with the screened Coulomb interaction $V_{eff}({\bf q},ω)$ within the $CuO_2$ plane of high $T_c$ superconductors. This pairing instability arises (via the dielectric constant) from wave-vector structure in $V_{eff}({\bf q},ω)$ at ${\bf q}=(π,π)$, which is associated with 2D

Anders W. Sandvik

The spin-lattice relaxation rate $1/T_1$ and the spin echo decay rate $1/T_{2G}$ for the spin-$1\over 2$ antiferromagnetic Heisenberg chain are calculated using quantum Monte Carlo and maximum entropy analytic continuation. The results are compared with recent analytical calculations by Sachdev. If the nuclear hyperfine form factor $A_q$ is strongly peaked a

A. Belkasri, F. D. Buzatu

Different kinds of instabilities (CDW, SDW, SS) in the 1D Hubbard model with pair-hopping interaction are investigated using an approximate Bethe-Salpeter equation. The study is performed at any density of electrons and for arbitrary values of the model parameters. In the absence of the on-site interaction, no transition occurs at half filling for any finite

A. Linke, D. W. Heermann, P. Altevogt, M. Siegert

We present Monte Carlo simulation results for the dynamical critical exponent $z$ of the two-dimensional kinetic Ising model using a lattice of size $10^6 \times 10^6$ spins. We used Glauber as well as Metropolis dynamics. The $z$-value of $2.16\pm 0.005$ was calculated from the magnetization and energy relaxation from an ordered state towards the equilibriu

P. De Los Rios, N. Manini, E. Tosatti

We study the Jahn-Teller effect of positive fullerene ions $^2$C$_{60}^{+}$ and $^1$C$_{60}^{2+}$. The aim is to discover if this case, in analogy with the negative ion, possesses a Berry phase or not, and what are the consequences on dynamical Jahn-Teller quantization. Working in the linear and spherical approximation, we find no Berry phase in $^1$C$_{60}^

P. J. Forrester, B. Jancovici, G. Tellez

Coulomb systems in which the particles interact through the $d$-dimensional Coulomb potential but are confined in a flat manifold of dimension $d - 1$ are considered. The Coulomb potential is defined with some boundary condition involving a characteristic macroscopic distance $W$ in the direction perpendicular to the manifold~: either it is periodic of perio

P. J. Forrester, B. Jancovici

The classical two-dimensional one-component plasma is an exactly solvable model, at some special temperature, even when the one-body potential acting on the particles has a quadrupolar term. As a supplement to a recent work of Di Francesco, Gaudin, Itzykson, and Lesage [{\it Int. J. Mod. Phys.} {\bf A9}, 4257 (1994)] about an $N$-particle system ($N$ large b

Erwin Frey

A field theoretic renormalization group method is presented which is capable of dealing with crossover problems associated with a change in the upper critical dimension. The method leads to flow functions for the parameters and coupling constants of the model which depend on the set of parameters which characterize the fixed point landscape of the underlying

E. K. U. Gross, M. Petersilka, T. Grabo

We analyze the difference between the correlation energy as defined within the conventional quantum chemistry framework and its namesake in density-functional theory. Both quantities are rigorously defined concepts; one finds that $E_c^{QC} \geq E_c^{DFT}$. We give numerical and analytical arguments suggesting that the numerical difference between the two ri

M. H. van Kerkwijk, S. R. Kulkarni

We present spectra of the white-dwarf companions of the radio pulsars 0655+64 and 0820+02. For the latter, we find a spectrum showing strong lines of hydrogen, i.e., that of a DA star. From modelling these lines, the mass of a white dwarf can, in principle, be determined accurately, thus leading to constraints on the evolution of the binary and the mass of t

Anita L. Cochran, Harold F. Levison, S. Alan Stern, Martin J. Duncan

We report the statistical detection (at the >99% confidence level) of a population of 28th magnitude objects exhibiting proper motions of ~1 arcsecond per hour at quadrature in deep HST/WFPC2 images. The drift directions imply a preponderance of objects on prograde orbits concentrated near the ecliptic plane. We interpret this as the detection of objects whi

Buell T. Jannuzi, Richard Elston, Gary D. Schmidt, Paul S. Smith

We have detected spatially extended linear polarized UV emission from the high-redshift radio galaxy 3C~256 ($z=1.82$). A spatially integrated ($7.8''$ diameter aperture) measurement of the degree of polarization of the $V-$band (rest frame 0.19 $μ$m) emission yields a value of 16.4\% ($\pm 2.2$\%) with a position angle of $42{}\rlap{\rm .}^\circ 4$

C. Steidel

We present results of surveys for high redshift galaxies selected by their having produced detectable Mg~II and Lyman limit absorption in the spectra of background QSOs. We discuss the properties of the absorbing galaxies, the connection between galaxy properties and absorption line signatures, and how a combination of QSO absorption line and conventional fa

L. S. Nazarova, P. T. O'Brien, M. J. Ward

We present deep long slit spectra of Mkn79 in position angles PA=12$^{o}$ and PA=50$^{o}$ obtained with the WHT. These data prove the existence of an extended narrow line region in PA=12$^{o}$, which coincides with the triplet radio structure (Ulvestad \& Wilson 1984) and the observed outflow of material from the nucleus at PA=10$^{o}$ (Whittle et al. 1988).

A. C. Fabian, M. J. Rees

Most large elliptical galaxies should now host a massive black hole leftover from an earlier quasar phase. Such galaxies also have an extensive hot gaseous halo. Here we consider why the nuclei of elliptical galaxies are not luminous sources due to the accretion of the hot gas by the central black hole, yet have weak radio sources. In particular we suggest t

I. Aretxaga, B. J. Boyle, R. J. Terlevich

Based on an $R$-band imaging survey of high-redshift ($z \approx 2$) QSOs with the 4.2m WHT, we report the detection of extensions to the nuclear PSFs of two radio-quiet and one radio-loud QSO. The extensions are most likely host galaxies, with luminosities of at least $3-7$\% of the QSO luminosity. The most likely values for the luminosities lie in the rang

Silvia Zane, Luca Zampieri, Roberto Turolla, Aldo Treves

Old isolated accreting neutron stars may show up among unidentified soft X--ray sources detected by the ROSAT All Sky Survey. We argue that the chances of identification are greater for ONSs located in the closest overdense regions of the solar neighbourhood. In particular, we consider the neutral hydrogen wall in the second Galactic quadrant ($15^\circ < l

Francesco Haardt, Piero Madau

We present a detailed calculation of the propagation of AGN-like ionizing radiation through the intergalactic space. We model the ionization state of absorbing clouds, and show that the universe will be more opaque above $4\,$Ryd than previously estimated. Singly ionized helium in \Lya forest clouds and Lyman-limit systems is found to be very efficient in re

F. K. Sutaria, A. Ray

Electron-capture and $β$-decay of nuclei in the core of massive stars play an important role in the stages leading to a type II supernova explosion. Nuclei in the f-p shell are particularly important for these reactions in the post Silicon-burning stage of a presupernova star. In this paper, we characterise the energy distribution of the Gamow-Teller Giant R

The JACEE Collaboration, K. Asakimori

The Japanese-American Cooperative Emulsion Experiment (JACEE) has recently carried out a series of Antarctic circumpolar balloon flights (JACEE-10 ~ JACEE-13) for the study of high energy elemental composition and energy spectra of cosmic rays. The total exposure factor of these experiments is 663 m**2-hr, which is about twice the cumulative exposure from JA

Slava G. Turyshev

A class of exact static spherically symmetric solutions of the Einstein-Maxwell gravity coupled to a massless scalar field has been obtained in harmonic coordinates of the Minkowski space-time. For each value of the coupling constant $a$, these solutions are characterized by a set of three parameters, the physical mass $μ_0$, the electric charge $Q_0$ and th

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

We formulate a random matrix model which mimics the chiral phase transition in QCD with two light flavors. Two critical exponents are calculated. We obtain the mean field values $β= \frac 12 $ and $δ= 3$. We also find that the chiral phase transition can be characterized by the dynamics of the smallest eigenvalue of the Dirac operator. This suggests an alter

V. P. Gusynin, V. A. Miransky, I. A. Shovkovy

It is shown that a constant magnetic field in 3+1 and 2+1 dimensions is a strong catalyst of dynamical chiral symmetry breaking, leading to the generation of a fermion dynamical mass even at the weakest attractive interaction between fermions. The essence of this effect is the dimensional reduction $D\to D-2$ in the dynamics of fermion pairing in a magnetic

G. J. Chaitin

Lecture given Friday 7 April 1995 at the Santa Fe Institute, Santa Fe, New Mexico. The lecture was videotaped; this is an edited transcript.

G. G. Athanasiu, E. G. Floratos, S. Nicolis

We construct explicitly the quantization of classical linear maps of $SL(2, R)$ on toroidal phase space, of arbitrary modulus, using the holomorphic (chiral) version of the metaplectic representation. We show that Finite Quantum Mechanics (FQM) on tori of arbitrary integer discretization, is a consistent restriction of the holomorphic quantization of $SL(2,

K. Kimura, M. Kitazawa, K. Tesima

One of the key ideas in describing the multiparticle production at high energies in the perturbative QCD is the angular ordering in successive soft-gluon emission. We analyse the angular distribution of particles in a jet, and investigate the corrections to the angular ordering. At a small angle from the jet direction, the angular ordering is exact at the ne

A. Schafer

The complementarity of polarized DIS experiments and polarized Proton-Proton experiments is illustrated for two examples. It is shown how the twist-3 part of the second moment of $g_2(x,Q^2)$ and the single-spin photon asymmetry are connected and it is discussed how the polarized gluon distribution can be obtained from the measurement of direct gamma asymmet

G. J. Gounaris, F. M. Renard, N. D. Vlachos

We show how the processes $e^- e^+ \to ZH, ~ γH$, which will be studied at LEP2 and at high energy colliders, could be used to search for types of New Physics (NP) characterized by an effective NP scale in the few TeV range and affecting the scalar sector only. In particular, for $e^- e^+ \to Z H$, we propose the measurement of suitable azimuthal asymmetries

Robert Bluhm, Alan Kostelecky, Bogdan Tudose

We present a theoretical construction for closest-to-classical wave packets localized in both angular and radial coordinates and moving on a keplerian orbit. The method produces a family of elliptical squeezed states for the planar Coulomb problem that minimize appropriate uncertainty relations in radial and angular coordinates. The time evolution of these s

Karin Berndl

It is shown that Bohmian mechanics is internally consistent in the sense that the equations of motion typically have global solutions despite the fact that the velocity field is singular at the nodes of the wave function and at other points. This result is fundamental for the derivation of the quantum formalism. The role of the quantum flux is emphasized.

S. M. Sergeev, H. E. Boos, V. V Mangazeev, Yu. G. Stroganov

In this paper we apply the method of psi-vectors to three dimensional statistical models. This method gives the correspondence between the Bazhanov -- Baxter model and its vertex formulation. Considering psi-vectors for the Planar model, we obtain its self-duality.

J. R. Bennett, J. Engel, S. Pittel

We study the structure of nucleon pairs within a simple model consisting of a square well in three dimensions and a delta-function residual interaction between two weakly-bound particles at the Fermi surface. We include the continuum by enclosing the entire system in a large spherical box. To a good approximation, the continuum can be replaced by a small set

E. M. Terentjev

The thermodynamic stability of emulsions of liquid crystal in water (glycerol) matrices is demonstrated for a wide range of materials and concentrations. Coalescence is prevented by an energy barrier for a topological ring defect formation in a neck between the two merging droplets. There is a characteristic size of emulsion droplets, typically tens of micro

Claude Laflamme

We discuss F(sigma) filters and show that the minimum size of a filter base generating an undiagonalizable filter included in some F(sigma) filter is the better known bounded evasion number e(ubd). An application to N-sets from trigonometric series is given by showing that if A is an N-set and B has size less e(ubd), then A+B is again an N-set.

E. Sokatchev

The $N=4$ supersymmetric self-dual Yang-Mills theory in a four- dimensional space with signature $(2,2)$ is formulated in harmonic superspace. The on-shell constraints of the theory are reformulated in the equivalent form of vanishing curvature conditions for three gauge connections (one harmonic and two space-time). The constraints are then obtained as vari

N. Nakazawa

In quantizing gravity based on stochastic quantization method, the stochastic time plays a role of the proper time. We study 2D and 4D Euclidean quantum gravity in this context. By applying stochastic quantization method to real symmetric matrix models, it is shown that the stochastic process defined by the Langevin equation in loop space describes the time

Michael Gronau, Jonathan L. Rosner

A quadrangle relation is shown to be satisfied by the amplitudes for $B^+ \to π^0 K^+,~π^+ K^0,~ηK^+$, and $η&#39; K^+$. By comparison with the corresponding relation satisfied by $B^-$ decay amplitudes, it is shown that the relative phases of all the amplitudes can be determined up to discrete ambiguities. Making use of an SU(3) relation between amplitudes

Edi Halyo

We show that large string threshold corrections can reconcile the string and MSSM unification scales in fermionic strings. This requires at least three moduli with large VEVs which are different from each other and MSSM states arising in an unconventional manner from the string spectrum. The former is easily achieved by supersymmetry breaking by both hidden

T. Kleinwort, G. Kramer

We have calculated inclusive one-- and two--jet production in photon--photon collisions in next--to--leading order superimposing direct, single resolved and double resolved cross sections. The results are compared with recent experimental data from the TOPAZ and AMY collaborations at TRISTAN. Good agreement is found between experiment and the theoretical res

Jae Kwan Kim, Yeong Gyun Kim, Jae Sik Lee, Kang Young Lee

We implement global fits to LEP data with the \non interactions. Consistent $R_b$ with experimental value and consistent $\as(M_Z^2)$ with that from low energy experiments are obtained. We also find that the $\xx$ is better than the Standard Model. And we argue that other kinds of new physics are needed to explain the difference between the values of $\as(M_

Jae Kwan Kim, Yeong Gyun Kim

We suggest a strategy for detecting $b$ polarization effects in $e^+e^-$ annihilation on $Z$ resonance. Using two types of inclusive leptonic samples with different ${Λ_b}$ fractions in $Z \ra b\bar{b}$ events, the $b$ polarization effects may be detected without large uncertainties of $b$ fragmentation and ${Λ_b}$ decay model.

J. L. Alonso, Ph. Boucaud, A. J. van der Sijs

We report on a simulation in progress of an SU(2) X U(1) fermion-Higgs model with two *non-degenerate* fermion doublets. The Zaragoza proposal for chiral lattice fermions is used; naive fermions are studied for comparison. The aims of this simulation are a non-perturbative study of the decoupling of species doublers, of triviality bounds on the Higgs and fer

Terrence Draper, Craig McNeile

Various properties of heavy-light mesons are determined, including decay constants, the $B_{B}$-parameter, and the Isgur-Wise function. The heavy (bottom) quark is simulated with the static, NRQCD and/or (fixed-velocity) lattice-HQET effective theories, using optimally-smeared sources as produced by the ``Maximal Operator Smearing Technique&#39;&#39;.

M. Goeckeler, H. A. Kastrup, J. Viola, J. Westphalen

We extract scattering phases for fermion-fermion scattering from Monte Carlo simulations of the two-dimensional Gross-Neveu model. This is done by means of Lüscher&#39;s method, which exploits the volume dependence of the energies of two-particle states. The results are compared with the analytical predictions.

V. Bashkov, A. Tchernomorov

In the present paper the idea is proposed to solve Maxwell equations for a curved hollow wave conductor by means of effective Riemannian space, in which the lines of motion of fotons are isotropic geodesies for a 4-dimensional space-time. The algorithm of constructing such a metric and curvature tensor components are written down explicitly. The result is in

Arthur M. Aslanyan

We investigate non-linear generalization of Maxwell theory of electromagnetic field keeping the gauge invariance of Lagrangian. New theory, which is standard Yang-Mills theory, is based on Harmonic Oscillator HO(4,R) gauge group. It&#39;s a solvable Lie group with nilpotent normal subgroup of codimension 1. We write down the Yang-Mills equation and point out

C. Godreche, J. M. Luck, M. R. Evans, D. Mukamel

It has been recently suggested that a totally asymmetric exclusion process with two species on an open chain could exhibit spontaneous symmetry breaking in some range of the parameters defining its dynamics. The symmetry breaking is manifested by the existence of a phase in which the densities of the two species are not equal. In order to provide a more rigo

Yigal Meir

A variational $ν=2/3$ state, which unifies the sharp edge picture of MacDonald with the soft edge picture of Chang and of Beenakker is presented and studied in detail. Using an exact relation between correlation functions of this state and those of the Laughlin $ν=1/3$ wavefunction, the correlation functions of the $ν=2/3$ state are determined via a classica

Emilio Artacho, Joerg Zegenhagen

A method is presented to obtain {\it ab initio} upper and lower bounds to surface energies of stress-driven discommensurate surface structures, possibly non-periodic or exhibiting very large unit cells. The instability of the stressed, commensurate parent of the discommensurate structure sets an upper bound to its surface energy; a lower bound is defined by

M. Büttiker, C. A. Stafford

The transfer of charge between different regions of a phase-coherent mesoscopic sample is investigated. Charge transfer from a side branch quantum dot into a ring changes the persistent current through a sequence of plateaus of diamagnetic and paramagnetic states. In contrast, a quantum dot embedded in a ring exhibits sharp resonances in the persistent curre

Jean Desbois, Cyril Furtlehner, Stéphane Ouvry

The 2-dimensional density of states of an electron is studied for a Poissonian random distribution of point vortices carrying $α$ flux in unit of the quantum of flux. It is shown that, for any given density of impurities, there is a transition, when $α\simeq 0.3-0.4$, from an &#34;almost free&#34; density of state -with only a depletion of states at the bott

E. M. Terentjev, M. Warner, G. C. Verwey

We develop a molecular model of non-uniform deformations within the framework of liquid crystal rubber elasticity. We show that, similarly to the uniform case, the theory is not sensitive to the molecular details of polymer liquid crystal involved and the resulting elastic free energy is quite universal. The result of this work is the general expression for

Gyorgy Szabo, Attila Szolnoki

Generalized mean-field analysis has been performed to study the ordering process in a half-filled square lattice-gas model with repulsive nearest neighbor interaction under the influence of a uniform electric field. We have determined the configuration probabilities on 2-, 4-, 5-, and 6-point clusters excluding the possibility of sublattice ordering. The agr

R. Benzi, L. Biferale, S. Ciliberto, R. Tripiccione

We discuss a possible theoretical interpretation of the self scaling property of turbulent flows (Extended Self Similarity). Our interpretation predicts that, even in cases when ESS is not observed, a generalized self scaling, must be observed. This prediction is checked on a number of laboratory experiments and direct numerical simulations.

S. Degl&#39;Innocenti, G. Fiorentini, G. G. Raffelt, B. Ricci

A variation of Newton&#39;s constant $G$ over cosmological time scales would modify the main-squence time of globular cluster (GC) stars. We have calculated the evolution of low-mass stars typical for GCs both for standard non-varying $G$ and under the assumption of a linear variation of $G$. The age of the isochrones resulting from the latter models then wa

C. Steidel, M. Pettini, D. Hamilton

We present the results of deep Lyman limit imaging in four new fields as part of a continuing search for galaxies at $3.0 \le z \le 3.5$. The technique uses a custom broad--band filter set ($U_n G {\cal R}$) designed to isolate objects having Lyman continuum breaks superposed on otherwise flat--spectrum ultraviolet continua. The observations are specifically

Wesley Chen, David A. Neufeld

We have modeled the far-infrared water line emission expected from circumstellar outflows from oxygen-rich late-type stars, as a function of the mass-loss rate and the terminal outflow velocity. For each mass-loss rate and terminal outflow velocity considered, we computed self-consistently the gas density, temperature, outflow velocity, and water abundance a

Colin J. Philp, Charles R. Evans, Peter J. T. Leonard, Dale A. Frail

We have conducted a VLA search for radio pulsars at the positions of 44 nearby OB runaway stars. The observations involved both searching images for point sources of continuum emission and a time series analysis. Our mean flux sensitivity to pulsars slower than 50 ms was 0.2 mJy. No new pulsars were found in the survey. The size of the survey, combined with

Takahiko Matsubara, Jun&#39;ichi Yokoyama

As a statistical measure to quantify the topological structure of the large-scale structure in the universe, the genus number is calculated for a number of non-Gaussian distributions in which the density field is characterized by a nontrivial function of some Gaussian-distributed random numbers. As a specific example, the formulae for the lognormal and the c

Fritjof Flechsig, Anton K. Rebhan

The conventional results for hard thermal loops, which are the building blocks of resummed perturbation theory in thermal field theories, have collinear singularities when external momenta are light-like. It is shown that by taking into account asymptotic thermal masses these singularities are removed. The thus improved hard thermal loops can be summarized b

T. Gannon, M. A. Walton

We discuss the existence of Galois relations obeyed by certain link invariants. Some of these relations have recently been identified and exploited within the context of CFT and Lie/Kac-Moody representation theory. These relations should aid in computing knot invariants. They probably have an interpretation in terms of quasitriangular (quasi-)Hopf algebras.

H. P. Fang

In order to investigate the evolutionary process of many deterministic Dynamical systems with unfixed parameter, a set of dynamical models with parameter changing continuously and the accumulation of this change might be large is introduced and discussed. The boundary crises and the period-doubling bifurcations are found suppressed and scaling properties for

L. L. Frankfurt, W. Koepf, M. Strikman

Hard diffractive electroproduction of longitudinally polarized vector mesons is calculated within the leading $α_s\ln{Q^2\overΛ_{QCD}^2}$ approximation of QCD using the leading order parton densities within the nucleon. Novel QCD features of the production of excited states and of the restoration of flavor symmetry are analyzed. At the onset of the asymptoti

Craig A. Tracy, Harold Widom

The focus of this paper is on the probability, $E_β(0;J)$, that a set $J$ consisting of a finite union of intervals contains no eigenvalues for the finite $N$ Gaussian Orthogonal ($β=1$) and Gaussian Symplectic ($β=4$) Ensembles and their respective scaling limits both in the bulk and at the edge of the spectrum. We show how these probabilities can be expres

John Ellis, Einan Gardi, Marek Karliner, Mark A. Samuel

We prove that Pade approximants yield increasingly accurate predictions of higher-order coefficients in QCD perturbation series whose high-order behaviour is governed by a renormalon. We also prove that this convergence is accelerated if the perturbative series is Borel transformed. We apply Pade approximants and Borel transforms to the known perturbative co