October 1997 arXiv papers — page 18

T. Hotta, T. Izubuchi, J. Nishimura

We investigate a new phase structure of the three-dimensional dynamical triangulation model with an additional local term by Monte Carlo simulation. We find that the first order phase transition observed for the naive Einstein-Hilbert action terminates at a finite coefficient of the new term. The phase transition turns into second order at the endpoint, beyo

William M. Pezzaglia

A generalized Clifford manifold is proposed in which there are coordinates not only for the basis vector generators, but for each element of the Clifford group, including the identity scalar. These new quantities are physically interpreted to represent internal structure of matter (e.g. classical or quantum spin). The generalized Dirac operator must now incl

Robert B. Griffiths, James B. Hartle

In a recent paper Kent has pointed out that in consistent histories quantum theory it is possible, given initial and final states, to construct two different consistent families of histories, in each of which there is a proposition that can be inferred with probability one, and such that the projectors representing these two propositions are mutually orthogo

M. A. H. MacCallum

A criterion given by Castejon-Amenedo and MacCallum (1990) for the existence of (locally) hypersurface-orthogonal generators of an orthogonally-transitive two-parameter Abelian group of motions (a $G_2I$) in spacetime is re-expressed as a test for linear dependence with constant coefficients between the three components of the metric in the orbits in canonic

Masaru Shibata, Ken-ichi Oohara, Takashi Nakamura

We present numerical results on the hydrodynamic stability of coalescing binary stars in the first post Newtonian(1PN) approximation of general relativity. We pay particular attention to the hydrodynamical instability of corotating binary stars in equilibrium states assuming the stiff polytropic equation of state with the adiabatic constant $Γ=3$. In previou

W. Rudnicki

According to the cosmic censorship hypothesis of Penrose, naked singularities should never occur in realistic collapse situations. One of the major open problems in this context is the existence of a naked singularity in the Kerr solution with |a|>m; this singularity can be interpreted as the final product of collapse of a rapidly rotating object. Assuming t

Bryan Clair

We generalize Luck's Theorem to show that the L^2-Betti numbers of a residually amenable covering space are the limit of the L^2-Betti numbers of a sequence of amenable covering spaces. We show that any residually amenable covering space of a finite simplicial complex is of determinant class, and that the L^2 torsion is a homotopy invariant for such spac

Christian D. Lorenz, Robert M. Ziff

Extensive Monte-Carlo simulations were performed to study bond percolation on the simple cubic (s.c.), face-centered cubic (f.c.c.), and body-centered cubic (b.c.c.) lattices, using an epidemic kind of approach. These simulations provide very precise values of the critical thresholds for each of the lattices: pc(s.c.) = 0.248 812 6(5), pc(f.c.c.) = 0.120 163

Dora Izzo, Gilson Carneiro

The occurrence of quasi-long-range positional order in the ground-state of the one-dimensional repulsive Calogero-Sutherland model is studied. By mapping the exact ground-state into a one dimensional classical system of interacting particles at finite temperatures the structure function and the displacement correlation functions are calculated numerically us

M. P. Lilly, J. P. Eisenstein, L. N. Pfeiffer, K. W. West

Coulomb drag resulting from interlayer electron-electron scattering in double layer 2D electron systems at high magnetic field has been measured. Within the lowest Landau level the observed drag resistance exceeds its zero magnetic value by factors of typically 1000. At half-filling of the lowest Landau level in each layer (nu = 1/2) the data suggest that ou

J. Feinberg, A. Zee

Recent analytical and numerical work have shown that the spectrum of the random non-hermitean Hamiltonian on a ring which models the physics of vortex line pinning in superconductors is one dimensional. In the maximally non-hermitean limit, we give a simple "one-line" proof of this feature. We then study the spectral curves for various distributions

Alexander J. Wagner, J. M. Yeomans

We present evidence, based on lattice Boltzmann simulations, to show that the coarsening of the domains in phase separating binary fluids is not a scale-invariant process. Moreover we emphasise that the pathway by which phase separation occurs depends strongly on the relation between diffusive and hydrodynamic time scales.

Maxim Mostovoy, Jasper Knoester

We study disordered Peierls systems described by the Fluctuating Gap Model. We show that the typical electron states with energies lying deep inside the pseudogap are localized near large disorder fluctuations (instantons), which have the form of a soliton-antisoliton pair. Using the ``saddle-point'' method we obtain the average density of states and

Torsten Henning

Niobium thin film nanostructures were fabricated using electron beam lithography and a liftoff process involving a four layer resist system. Wires having micrometres in length and below 200 nm in width were deposited on an insulating substrate and subsequently thinned by anodisation. The resistance of the wires was monitored in situ and could be trimmed by c

Imre Varga, Yoshiyuki Ono, Tomi Ohtsuki, Janos Pipek

The shape analysis of the energy spacing distribution $P(s)$ obtained from numerical simulation of two dimensional disordered electron systems subject to strong magnetic fields is performed. In the present work we reanalyze the data obtained in a previous publication. Special moments of the $P(s)$ function related to Rényi-entropy differences show a novel sc

G. Bilalbegovic, H. O. Lutz

We study lead nanodroplets containing 147 to 1415 atoms at temperatures ranging from the bulk melting point up to the beginning of the evaporation regime. Molecular dynamics simulation and an embedded atom potential are used. The structures, total energies, and mobility of atoms in the clusters are analyzed. We found that the liquid cluster of 147 atoms show

A. W. Tyler, Yoichi Ando, F. F. Balakirev, A. Passner

We present a study of in-plane normal state magneto-transport in single crystal Tl-2201 in 60T pulsed magnetic fields. In optimally doped samples (Tc ~ 80K) the weak-magnetic-field regime extends to fields as high as 60T, but in overdoped samples (Tc ~ 30K) we are able to leave the weak field regime, as shown by the behavior of both the magnetoresistance and

Marko Robnik, Luca Salasnich

By using the WKB quantization we deduce an analytical formula for the energy splitting in a double-well potential which is the usual Landau formula with additional quantum corrections. Then we analyze the accuracy of our formula for the double square well potential and the parabolic double-well potential.

Paul Hickson, Mark K. Mulrooney

Observations, analysis techniques and photometric properties of a multi-narrowband survey of a 20 square-degree area of sky at +33 degrees declination are described. The survey is conducted with the 3-meter liquid-mirror telescope of the NASA Orbital Debris Observatory using intermediate-bandwidth filters. These filters have central wavelengths ranging from

Thomas Quinn, Neal Katz, Joachim Stadel, George Lake

Leapfrog integration has been the method of choice in N-body simulations owing to its low computational cost for a symplectic integrator with second order accuracy. We introduce a new leapfrog integrator that allows for variable timesteps for each particle in large N-body simulations. Tests with single particles in fixed potentials show that it behaves as a

Liliya L. R. Williams, Geraint F. Lewis

To date, the study of high-magnification gravitational lensing effects of galaxy clusters has focused upon the grossly distorted, luminous arc-like features formed in massive, centrally condensed clusters. We investigate the formation of a different type of image, highly magnified yet undistorted, in two widely employed cluster mass density profiles; an isot

Rebecca A. W. Elson, Carl J. Grillmair, Duncan A. Forbes, Mike Rabban

We present B and I photometry for ~300 globular cluster candidates in NGC 1379, an E0 galaxy in the Fornax Cluster. Our data are from both Hubble Space Telescope (HST) and ground-based observations. The HST photometry (B only) is essentially complete and free of foreground/background contamination to ~2 mag fainter than the peak of the globular cluster lumin

F. Palla, D. Galli, R. Bachiller, M. Perez Gutierrez

We present the results of a study aimed at determining the 12C/13C ratio in two samples of planetary nebuale (PNe) by means of mm-wave observations of 12CO and 13CO. The first group includes six PNe which have been observed in the 3He+ hyperfine transition; the other group consists of 23 nebulae with rich molecular envelopes. We have determined the isotopic

V. F. Mukhanov, Paul J. Steinhardt

We derive a closed-form, analytical expression for the spectrum of long-wavelength density perturbations in inflationary models with two (or more) inflaton degrees of freedom that is valid in the slow-roll approximation. We illustrate several classes of potentials for which this expression reduces to a simple, algebraic expression.

Yosuke Imamura

We study the propagations of gravitational wave and D-particle on D6-brane and orientifold 6-plane backgrounds in the M-theory framework. In the case of orientifold plane, D-particle number is not conserved and gravitational wave can convert into D-particle. For the simplest case, we calculate its amplitude numerically.

Juan M. Maldacena, Andrew Strominger

We argue that a near-extremal charge-$k$ type II NS fivebrane can be reliably described in semiclassical string perturbation theory as long as both $k$ and $μ\over k$ are large, where $μ$ is the energy density in string units. For a small value of the asymptotic string coupling $g$, the dynamics in the throat surrounding the fivebrane reduces to the CGHS mod

J. Adam,, J. W. Van Orden, Franz Gross

This paper presents a new non-associative algebra which is used to (i) show how the spectator (or Gross) two-body equations and electromagnetic currents can be formally derived from the Bethe-Salpeter equation and currents if both are treated to all orders, (ii) obtain explicit expressions for the Gross two-body electromagnetic currents valid to any order, a

R. Argurio, L. Houart

We discuss theories with 16 and 8 supercharges in 6 and 7 dimensions. These theories are defined as world-volume theories of 5- and 6-branes of type II and M theories, in the limit in which bulk modes decouple. We analyze in detail the spectrum of BPS extended objects of these theories, and show that the 6 dimensional ones can be interpreted as little (non-c

M. Gomes, A. J. da Silva

Starting from a relativistic quantum field theory, we study the low energy scattering of two fermions of opposite spins interacting through a Chern-Simons field. Using the Coulomb gauge we implement the one loop renormalization program and discuss vacuum polarization and magnetic moment effects. We prove that the induced magnetic moments for spin up and spin

S. Ambrosanio, Graham D. Kribs, Stephen P. Martin

In models with low-energy supersymmetry breaking, it is well-known that charged sleptons can be significantly lighter than the lightest neutralino, with the gravitino and lighter stau being the lightest and next-to-lightest supersymmetric particles respectively. We give analytical formulas for the three-body decays of right-handed selectrons and smuons into

A. Kehagias, H. Partouche

We propose a four-point effective action for the graviton, antisymmetric two-forms, dilaton and axion of type IIB superstring in ten dimensions. It is explicitly SL(2,Z)-invariant and reproduces the known tree-level results. Perturbatively, it has only one-loop corrections for the NS-NS sector, generalizing the non-renormalization theorem of the R^4 term. Fi

D. Fargion, B. Mele, A. Salis

The diffuse relic neutrinos with light mass are transparent to Ultrahigh energy (UHE) neutrinos at thousands EeV, born by photoproduction of pions by UHE protons on relic 2.73 K BBR radiation and originated in AGNs at cosmic distances. However these UHE $ν$s may interact with those (mainly heaviest $ν_{μ_r}$, $ν_{τ_r}$ and respective antineutrinos) clustered

M. Alishahiha

We construct type II A brane configuration of N=(4,4) supersymmetric two dimensional gauge theory with gauge group U(1) and N_f hypermultiplets in the fundamental representation. By lifting to M-theory (strong coupling), we can see the origin of the R-symmetry enhancement of the Coulomb branch. One can also find two theories which become equivalent at strong

Gesualdo Delfino

We use the results of integrable field theory to determine the universal amplitude ratios in the two-dimensional Ising model. In particular, the exact values of the ratios involving amplitudes computed at nonzero magnetic field are provided.

Andrzej Borowiec

A notion of Cartan pairs as an analogy of vector fields in the realm of noncommutative geometry has been proposed in q-alg/9609011 In this paper we give an outline of the construction of a noncommutative analogy of the algebra of partial differential operators as well as its natural (Fock type) representation. We shall also define co-universal vector fields

M. N. Chernodub, F. V. Gubarev, E. -M. Ilgenfritz

3D electroweak sphalerons on the lattice are used as test configurations for definitions of various topological defects. In the maximally Abelian gauge they are shown to contain a symmetric array of Abelian monopoles and anti-monopoles connected by two kinds of Abelian vortex strings. Gauge-invariant lattice definitions of the Nambu monopole and the Z-vortex

Toshiya Kawai

It has recently become apparent that the elliptic genera of K3 surfaces (and their symmetric products) are intimately related to the Igusa cusp form of weight ten. In this contribution, I survey this connection with an emphasis on string theoretic viewpoints.

S. M. Sergeev

A sort of two dimensional linear auxiliary problem for the complex of 3D $R$ -- operators associated with the Zamolodchikov -- Bazhanov -- Baxter statistical model is proposed. This problem resembles the problem of the local Yang -- Baxter equation but does not coincide with it. The formulation of the auxiliary problem admits a notion of a ``fusion''

T. Bahnik, J. Horejsi

Possible deviations from a low-energy theorem for the scattering of strongly interacting longitudinally polarized $W$ and $Z$ bosons are discussed within a particular scheme of electroweak symmetry breaking. The scheme (suggested earlier by other authors in a slightly different context) is based on spontaneous breakdown of a SU(4) symmetry to custodial SU(2)

Hiroshi Suzuki

When an asymptotically non-free theory possesses a mass parameter, the ultraviolet (UV) renormalon gives rise to non-perturbative contributions to dimension-four operators and dimensionless couplings, thus has a similar effect as the instanton. We illustrate this phenomenon in O(N) symmetric massive $λϕ^4$ model in the $1/N$ expansion. This effect of UV reno

Tomoko Kadoyoshi, Shin'ichi Nojiri, Sergei D. Odintsov, Akio Sugamoto

We study the vacuum polarization of supersymmetric toroidal D-brane placed in the constant electromagnetic field. Explicit calculation of the one-loop effective potential is performed for membrane with constant magnetic or electric background. We find the one-loop potentials vanish as the effect of supersymmetry,

Corneliu Sochichiu

Using a regularisation of the chiral SU(2) Yang-Mills model by an infinite number of Pauli-Villars fields the doubler free gauge invariant lattice model is constructed. Its continuum limit provides the recently proposed mechanism for cancelation of Witten anomaly.

K. -I. Izawa, T. Yanagida

We construct R-invariant grand unification models with composite Higgs multiplets. Higgs doublets are massless due to the R symmetry, which is not spontaneously broken at the unification scale, while Higgs triplets get large masses from a dynamically generated superpotential, which is allowed by an R anomaly.

Matt Visser

This note summarizes a model-independent analysis of the age of the universe problem that trades off precision in favour of robustness: The energy conditions of Einstein gravity are designed to extract as much information as possible from classical general relativity without specifying a particular equation of state. This is particularly useful in a cosmolog

Waldemar Puszkarz

We present an extension of Staruszkiewicz's modification of the Schrödinger equation which preserves its main and unique feature: in the natural system of units the modification terms do not contain any dimensional constants. The extension, similarly as the original, is formulated in a three-dimensional space and derives from a Galilean invariant Lagrang

D. Boschi, S. Branca, F. De Martini, L. Hardy

We report on a quantum optical experimental implementation of teleportation of unknown pure quantum states. This realizes all the nonlocal aspects of the original scheme proposed by Bennett et al. and is equivalent to it up to a local operation. We exhibit results for the teleportation of a linearly polarized state and of an elliptically polarized state. We

Valery P. Karassiov

Hamiltonians of a wide-spread class of strongly coupled quantum system models are expressed as nonlinear functions of $sl(2)$ generators. It enables us to use the $sl(2)$ formalism, in particular, $sl(2)$ generalized coherent states (GCS) for solving both spectral and evolution tasks. In such a manner, using standard variational schemes with $sl(2)$ GCS as t

Guo-xing Ju, Shi-kun Wang, Ke Wu

We extend the study on the algebraic structure of the $su(n)$ color Calogero-Sutherland models to the case of $gl(n|m)$ color CS model and show that the generators of the super-Yangian $Y(gl(n|m))$ can be obtained from two $gl(n|m)$ loop algebras. Also, a super $W_{\infty}$ algebra for the SUSY CS model is constructed.

S. Donev, M. Tashkova

This paper aims to present an elaborate view on the motivation and realization of the idea to extend Maxwell's electrodynamics to Extended Electrodynamics in a reasonable and appropriate way in order to make it possible to describe electromagnetic (3+1)-soliton-like objects in vacuum and in the presence of continuous media (external fields), exchanging e

Joseph N. Ginocchio, David G. Madland

We show that the occurrence of approximate pseudo-spin symmetry in nuclei is connected with certain similarities in the relativistic single-nucleon wave functions of the corresponding pseudo-spin doublets. We perform a case study in which several examples and the systematics of this connection are explored.

D. Hardtke, T. J. Humanic

Using a simple final-state rescattering model coupled with a simple Coulomb model, the effects of the central Coulomb potential on pion interferometry measurements in 158 GeV/nucleon Pb+Pb collisions are explored. Although the central Coulomb potential does not introduce correlations between pions, it does prevent an accurate measurement of the momentum diff

G. Q. Li

Theoretical and experimental studies of hot and/or dense matter, such as is created in high-energy heavy-ion collisions, and encountered in compact objects in astrophysics, constitute one of the most active frontiers in nuclear physics. In these Lectures, we discuss various approaches to the description of hot and/or dense matter, including the simple Skyrme

H. Herndl, H. Oberhummer

We investigate the thermal cross section of the reaction 13C(n,gamma)14}C which takes place in the helium burning zones of red giant star as well as in the nucleosynthesis of Inhomogeneous Big Bang models. We find that we can reproduce the experimentally known thermal capture cross section only if we take into account a strong hindrance of the E1 transition

Gustavo Dotti, Aneesh Manohar

The structure of the moduli space of N=1 supersymmetric gauge theories is analyzed from an algebraic geometric viewpoint. The connection between the fundamental fields of the ultraviolet theory, and the gauge invariant composite fields of the infrared theory is explained in detail. The results are then used to prove an anomaly matching theorem. The theorem i

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

Two closely related topological phenomena are studied at finite density and temperature. These are chiral anomaly and Chern-Simons term. By using different methods it is shown that $μ^2 = m^2$ is the crucial point for Chern-Simons at zero temperature. So when $μ^2 < m^2$ $μ$--influence disappears and we get the usual Chern-Simons term. On the other hand when

Ralph Blumenhagen

It is shown that the recently proposed target space duality for (0,2) models is not limited to models admitting a Landau-Ginzburg description. By studying some generic examples it is established for the broader class of vector bundles over complete intersections in toric varieties. Instead of sharing a common Landau-Ginzburg locus, a pair of dual models agre

John D. Barrow, Kerstin E. Kunze

We study the evolution of non-linear spherically symmetric inhomogeneities in string cosmology. Friedmann solutions of different spatial curvature are matched to produce solutions which describe the evolution of non-linear density and curvature inhomogeneities. The evolution of bound and unbound inhomogeneities are studied. The problem of primordial black ho

S. E. Derkachov, A. N. Manashov

The simple method for the calculating of the anomalous dimensions of the composite operators up to 1/N^2 order is developed. We demonstrate the effectiveness of this approach by computing the critical exponents of the $(\otimes\vecΦ)^{s}$ and $\vecΦ\otimes(\otimes\vec\partial)^{n}\vecΦ$ operators in the 1/N^2 order in the nonlinear sigma model. The special s

B. Piette, W. J. Zakrzewski

We report our observations that the baby-Skyrme model in (2+1) dimensions possesses non-topological stationary solutions which we call pseudo-breathers. We discuss their properties and present our results on their interaction with the topological skyrmions.

B. Piette, W. J. Zakrzewski

We study the 3+1 dimensional Skyrme model with a mass term different from the usual one. We show that this new model possesses domain walls solutions. We describe how, in the equivalent 2+1 dimensional model, the Skyrmion is absorbed by the wall.

Thomas. G. Rizzo

In this talk I summarize the capability of future lepton colliders to indirectly discover a new $Z&#39;$ and to determine its couplings to the fermions of the Standard Model. The physics associated with sitting on the $Z&#39;$-pole is also briefly discussed. This analysis is based on the results presented in the Snowmass 1996 New Gauge Boson Working Group re

J. P. B. C. de Melo, H. W. L. Naus, T. Frederico

The electromagnetic form factor of the pion is calculated in a pseudoscalar field theoretical model which constituent quarks. We extract the form factor using the &#34;+&#34; component of the electromagnetic current in the light-cone formalism. For comparison, we also compute the form factor in the covariant framework and we obtain perfect agreement. It is s

G. A. Schuler, M. Vänttinen

Inclusive production of $χ_{c J}$ in $e^+e^-$ annihilation is an excellent probe of the role of higher Fock states in the production of heavy quarkonia. Within the non-relativistic QCD approach, contributions from the short-distance production of colour-octet $c\bar{c}$ pairs are significantly larger than those from colour-singlet production. At the same tim

H. W. L. Naus, J. P. B. C de Melo, T. Frederico

The Ward-Takahashi identity, reflecting local gauge invariance, is perturbatively verified for a boson model in light front field theory. A careful integration over the light front energy, corresponding to exactly taking into account pair terms, which are the contributions of the zero longitudinal momentum mode, is crucial to obtain this result. Furthermore,

Ekaterina Christova, Dimitar Draganov

The top quark is expected to decay as a free particle with definite momentum and polarization. Here we consider the possibilities to obtain information about its polarization through the energy and angular distributions of the b-quarks from the decay of the top-quarks produced in $e^+e^-$ annihilation. Analytic expressions and numerical estimates for differe

C. Bourrely, J. Soffer, O. V. Teryaev

DGLAP evolution equations may be presented in a form completely analogous to the Boltzmann equation. This provides a natural proof of the positivity of the spin-dependent parton distributions, provided the initial distributions at $Q^2_0$ are also positive. In addition, the evolution to $Q^2 < Q^2_0$ may violate positivity, providing therefore a &#39;time ar

D. Boer, P. J. Mulders, O. V. Teryaev

We discuss the effects of so-called gluonic poles in twist-three hadronic matrix elements, as first considered by Qiu and Sterman, in the Drell-Yan process. These effects cannot be distinguished from those of time-reversal odd distribution functions, although time-reversal invariance is not broken by the presence of gluonic poles. Both gluonic poles and time

L. Avdeev, J. Fleischer, M. Yu. Kalmykov, M. N. Tentyukov

A method to calculate two-loop self-energy diagrams of the Standard Model is demonstrated. A direct physical application is the calculation of the two-loop electroweak contribution to the anomalous magnetic moment of the muon ${{1/2}(g-2)}_μ$. Presently, we confine ourselves to a ``toy&#39;&#39; model with only $μ$, $γ$ and a heavy neutral scalar particle (H

Minako Kitahara, Miho Marui, Noriyuki Oshimo, Tomomi Saito

The supersymmetric standard model contains a new CP-violating phase in the mass matrices for charginos and neutralinos, which could induce CP-odd anomalous couplings for the WWZ and WWγvertices at the one-loop level. We study these couplings, paying attention to the model-parameter and q^2 dependencies. It is shown that the CP-odd form factors could have val

A. A. Gvozdev, A. V. Kuznetsov, N. V. Mikheev, L. A. Vassilevskaya

The high energy neutrino transitions with the photon and electron-positron pair creation in a strong magnetic field in the framework of the Standard Model are investigated. The process probabilities and the mean values of the neutrino energy and momentum loss are presented. The asymmetry of outgoing neutrinos, as a possible source of sufficient recoil ``kick

J. J. Godina, Y. Meurice, S. Niermann

We calculate the high-temperature expansion of the 2-point function up to order 800 in beta. We show that estimations of the critical exponent gamma based on asymptotic analysis are not very accurate in presence of confluent logarithmic singularities. Using a direct comparison between the actual series and the series obtained from a parametrization of the fo

Howard D. Trottier, G. Peter Lepage

Perturbative estimates of operator coefficients for improved lattice actions are becoming increasingly important for precision simulations of many hadronic observables. Following previous work by Dimm, Lepage, and Mackenzie, we consider the feasibility of computing operator coefficients from numerical simulations deep in the perturbative region of lattice th

Alun George

For dynamical triangulations in dimensions d<=4 the most general action has two couplings. We note that the most general action for d=5 has three couplings. We explore this larger coupling space using Monte Carlo simulations. Initial results indicate evidence for non-trivial phase structure.

Hartmut Wittig

The status of simulations using the non-perturbatively O(a) improved Wilson action in the quenched approximation is reviewed. The impact of non-perturbative improvement on the hadronic mass spectrum and the size of residual lattice artefacts in spectral quantities and decay constants are assessed.

TchiL collaboration, G. S. Bali, N. Eicker, P. Lacock

We present results on the static potential, and torelon and glueball masses from simulations of QCD with two flavours of dynamical Wilson fermions on $16^3\times 32$ and $24^3\times 40$ lattices at $β=5.6$.

Sunao Sakai, Atsushi Nakamura, Takuya Saito

Numerical results for the transport coefficients of quark gluon plasma are calculated by lattice simulation of SU(3) pure gauge model. The bulk viscosity is consistent with zero. The shear viscosity is finite and increases with temperature $T$ roughly as $T^{3}$, and around the finite temperature transition points, it is slightly smaller than the typical had

C. J. Hamer, J. Oitmaa, Zheng Weihong

Strong-coupling series expansions are calculated for the Hamiltonian version of compact lattice electrodynamics in (2+1) dimensions, with 4-component fermions. Series are calculated for the ground-state energy per site, the chiral condensate, and the masses of `glueball&#39; and positronium states. Comparisons are made with results obtained by other techniqu

E. C. Aschenauer, J. Baehr, V. Gapienko, B. Hoffmann

The performance of a scintillating fiber detector prototype for tracking under high rate conditions is investigated. A spatial resolution of about100 micron is aimed for the detector. Further demands are low occupancy and radiation hardness up to 1 Mrad/year. Fibers with different radii and different wavelengths of the scintillation light from different prod

Rodolfo Gambini, Jerzy Lewandowski, Donald Marolf, Jorge Pullin

We point out several features of the quantum Hamiltonian constraints recently introduced by Thiemann for Euclidean gravity. In particular we discuss the issue of the constraint algebra and of the quantum realization of the object $q^{ab}V_b$, which is classically the Poisson Bracket of two Hamiltonians.

L. Herrera, H. Hernandez, L. A. Nunez, U. Percoco

We study different models of radiating slowly rotating bodies up to the first order in the angular velocity. It is shown that up to this order the evolution of the eccentricity is highly model-dependent even for very compact objects.

Jerzy Lewandowski, Donald Marolf

This work introduces a new space $\T&#39;_*$ of `vertex-smooth&#39; states for use in the loop approach to quantum gravity. Such states provide a natural domain for Euclidean Hamiltonian constraint operators of the type introduced by Thiemann (and using certain ideas of Rovelli and Smolin). In particular, such operators map $\T&#39;_*$ into itself, and so ar

Chris M. Chambers, Patrick R. Brady, William Krivan, Pablo Laguna

We summarize the results of an investigation into the late time behavior of massless scalar fields propagating on spherically symmetric black hole spacetimes with a non-zero cosmological constant. The compatibility of these results with the `minimal requirement&#39; of Brady and Poisson is commented upon.

Chris M. Chambers, Patrick R. Brady, Sergio M. C. V. Goncalves

We present the findings of an investigation of critical behavior in the collapse of spherically symmetric distributions of massive scalar field. Two distinct types of phase transition are observed at the verge of black hole formation and a criterion for determining when each type of transition will occur is given.

Chris M. Chambers, William A. Hiscock, Brett E. Taylor

We report and comment upon the principal results of an investigation into the evolution of rotating black holes emitting massless scalar radiation via the Hawking process. It is demonstrated that a Kerr black hole evaporating by the emission of scalar radiation will evolve towards a state with $a \approx 0.555M$. If the initial specific angular momentum is l

F. Vendrell

Theorems on the emission of massless scalar particles by the CGHS black hole are presented. The convergence of the mean number of particles created spontaneously in an arbitrary state is studied and shown to be strongly dependent on the infrared behavior of this state. A bound for this quantity is given and its asymptotic forms close to the horizon and far f

Hans-Peter Nollert, John Baker, Richard Price, Jorge Pullin

Perturbation techniques can be used as an alternative to supercomputer calculations in calculating gravitational radiation emitted by colliding black holes, provided the process starts with the black holes close to each other. We give a summary of the method and of the results obtained for various initial configurations, both axisymmetric and without symmetr

R. Bott, A. S. Cattaneo

This note describes an invariant of rational homology 3-spheres in terms of configuration space integrals which in some sense lies between the invariants of Axelrod and Singer and those of Kontsevich.

Xian-Geng Zhao, W. -X. Yan, Daniel W. Hone

Within a two-band tight binding model, we investigate the dynamics of electrons with Markoffian dephasing under the influence of static electric fields. With the help of both numerical and analytic calculations we find that the dephasing ultimately takes electrons which are initially located in one miniband to equal population of the two minibands, instead o

Ugo Bastolla, Helge Frauenkron, Erwin Gerstner, Peter Grassberger

We demonstrate that the recently proposed pruned-enriched Rosenbluth method PERM (P. Grassberger, Phys. Rev. E, in press (1997)) leads to extremely efficient algorithms for the folding of simple model proteins. We test it on several models for lattice heteropolymers, and compare to published Monte Carlo studies of the properties of particular sequences. In a

A. F. Volkov

In a recent paper Schechter, Imry and Levinson (cond-mat/9709248) \cite{r1} analysed the density-of-states (DOS) and the conductance of a S/N junction with a barrier. They showed that the DOS in the N conductor near the barrier is strongly affected by the superconductor if the energy $ε$ is small: $l_{n} \sqrt{ε/D}{\ll} Γ{\ll} 1$, where $l_{n}$ is the mean f

M. R. Ejtehadi, N. Hamedani, H. Seyed-Allaei, V. Shahrezaei

By exact computer enumeration and combinatorial methods, we have calculated the designability of proteins in a simple lattice H-P model for the protein folding problem. We show that if the strength of the non-additive part of the interaction potential becomes larger than a critical value, the degree of designability of structures will depend on the parameter

V. B. Shenoy, R. Miller, E. B. Tadmor, D. Rodney

Mixed atomistic and continuum methods offer the possibility of carrying out simulations of material properties at both larger length scales and longer times than direct atomistic calculations. The quasi-continuum method links atomistic and continuum models through the device of the finite element method which permits a reduction of the full set of atomistic

K. Mussawisade, T. Wichmann, K. W. Kehr

The diffusion coefficient of single particles in the presence of Ehrlich-Schwoebel barriers (ESB)is considered. An exact expression is given for the diffusion coefficient on linear chains with random arrangements of ESB. The results are extended to surfaces having ESB with uniform extension in one or both directions. All results are verified by Monte Carlo s

P. Garbaczewski

We analyze circumstances under which the microscopic dynamics of particles which are driven by a forced, gradient-type flow can be consistently interpreted as a Markovian diffusion process. Special attention is paid to discriminating between forces that are presumed to act selectively upon diffusing particles, while leaving the random medium statistically at

P. Simon

We analyse in this article the critical behavior of $M$ $q_1$-state Potts models coupled to $N$ $q_2$-state Potts models ($q_1,q_2\in [2..4]$) with and without disorder. The technics we use are based on perturbed conformal theories. Calculations have been performed at two loops. We already find some interesting situations in the pure case for some peculiar v

Normand Mousseau, G. T. Barkema

A detailed description of the activation-relaxation technique (ART) is presented. This method defines events in the configurational energy landscape of disordered materials, such as a-Si, glasses and polymers, in a two-step process: first, a configuration is activated from a local minimum to a nearby saddle-point; next, the configuration is relaxed to a new

Stefan Kammerer, Walter Kob, Rolf Schilling

Using molecular dynamics computer simulations we study the dynamics of a molecular liquid by means of a general class of time-dependent correlators S_{ll&#39;}^m(q,t) which explicitly involve translational (TDOF) and orientational degrees of freedom (ODOF). The system is composed of rigid, linear molecules with Lennard- Jones interactions. The q-dependence o

Stefan Kammerer, Walter Kob, Rolf Schilling

A molecular dynamics simulation is performed for a supercooled liquid of rigid diatomic molecules. The time-dependent self and collective density correlators of the molecular centers of mass are determined and compared with the predictions of the ideal mode coupling theory (MCT) for simple liquids. This is done in real as well as in momentum space. One of th

T. V. Shahbazyan, S. E. Ulloa

We study the energy spectrum of a system of localized states coupled to a 2D electron gas in strong magnetic field. If the energy levels of localized states are close to the electron energy in the plane, the system exhibits a kind of collective behavior analogous to the Dicke effect in optics. The latter manifests itself in ``trapping&#39;&#39; of electronic

Kazuhiko Kuroki, Hideo Aoki

Quantum Monte Carlo is used to calculate various pairing correlations of the 2D Hubbard model possessing band features experimentally observed in the cuprates. In the hole-doped case, where the Fermi level lies close to the van Hove singularities around $(0,π)$, the d$_{x^2-y^2}$ pairing correlation is selectively enhanced, while in the electron-doped case,