September 1994 arXiv papers — page 9

C. R. Fernandez-Pousa, M. V. Gallas, J. L. Miramontes, J. Sanchez Guillen

We derive sufficient conditions under which the ``second'' Hamiltonian structure of a class of generalized KdV-hierarchies defines one of the classical $\cal W$-algebras obtained through Drinfel'd-Sokolov Hamiltonian reduction. These integrable hierarchies are associated to the Heisenberg subalgebras of an untwisted affine Kac-Moody algebra. When

R. Schack

Given a list of $N$ states with probabilities $0<p_1\leq\cdots\leq p_N$, the average conditional algorithmic information $\bar I$ to specify one of these states obeys the inequality $H\leq\bar I<H+O(1)$, where $H=-\sum p_j\log_2p_j$ and $O(1)$ is a computer-dependent constant. We show how any universal computer can be slightly modified in such a way that the

Sergei V. Ketov

Possible ways of constructing extended fermionic strings with $N=4$ world-sheet supersymmetry are reviewed. String theory constraints form, in general, a non-linear quasi(super)conformal algebra, and can have conformal dimensions $\geq 1$. When $N=4$, the most general $N=4$ quasi-superconformal algebra to consider for string theory building is $\hat{D}(1,2;\

John Hiller, Steve Pinsky, Brett van de Sande

We investigate (1+1)-dimensional $ϕ^4$ field theory in the symmetric and broken phases using discrete light-front quantization. We calculate the perturbative solution of the zero-mode constraint equation for both the symmetric and broken phases and show that standard renormalization of the theory yields finite results. We study the perturbative zero-mode con

Kenichi Horie

A complete geometric unification of gravity and electromagnetism is proposed by considering two aspects of torsion: its relation to spin established in Einstein--Cartan theory and the possible interpretation of the torsion trace as the electromagnetic potential. Starting with a Lagrangian built of Dirac spinors, orthonormal tetrads, and a complex rather than

Sergei V. Ketov

The quantum BRST charge for the most general, two-dimensional, non-linear, $N=4$ quasi-superconformal algebra $\hat{D}(1,2;\a)$, whose linearisation is the so-called `large&#39; $N=4$ superconformal algebra, is constructed. The $\hat{D}(1,2;\a)$ algebra has $\Hat{su(2)}_{k^+}\oplus \Hat{su(2)}_{k^-}\oplus\Hat{u(1)}$ Kač-Moody component, and $\a=k^-/k^+$. As

Dimitris Kominis, Vassilis Koulovassilopoulos

We show that in Composite Higgs models, the coupling of the Higgs resonance to a pair of $W$ bosons is weaker than the corresponding Standard Model coupling, provided the Higgs arises from electroweak doublets only. This is partly due to the effects of the nonlinear realization of the chiral symmetries at the compositeness scale.

Alexander L. Kagan

Two of the outstanding discrepancies between weak interaction phenomenology and the standard model come in the large size of the $ΔI={1\over 2}$ enhancement in $K$ decays and in the small value of the $B$ semileptonic branching ratio. We argue that these discrepancies are naturally explained by chromomagnetic dipole operators arising from new physics at the

G. Hazak, R. Zamir

The {\em Van Cittert Zernike} theorem consists of a simple relation between the measured coherence of the radiation and the characteristics of the emitting stochastic source. In the present work, an extension of the theorem to partially correlated sources in curved spacetime is derived. The generalized theorem is used to evaluate the changes in the spectrum

Tohsuke Urabe

We treat nine of fourteen triangle singularities in Arnold&#39;s classification list of singularities. We consider what kind of combinations of rational double points can appear on their small deformation fibers. We show their combinations are described by a simple priciple using Dynkin graphs.

Alexander Belopolsky, Barton Zwiebach

We derive an explicit formula for the evaluation of the classical closed string action for any off-shell string field, and for the calculation of arbitrary off-shell amplitudes. The formulae require a parametrization, in terms of some moduli space coordinates, of the family of local coordinates needed to insert the off-shell states on Riemann surfaces. We di

A. Pineda, J. Soto

We use Heavy Quark Effective Theory (HQET) techniques to parametrize certain non-perturbative effects related to quantum fluctuations that put both heavy quark and antiquark in quarkonium almost on shell. The large off-shell momentum contributions are calculated using Coulomb type states. The almost on-shell momentum contributions are evaluated using an effe

Andrzej Sitarz

Following the construction of the $κ$-Minkowski space from the bicrossproduct structure of the $κ$-Poincare group, we investigate possible differential calculi on this noncommutative space. We discuss then the action of the Lorentz quantum algebra and prove that there are no 4D bicovariant differential calculi, which are Lorentz covariant. We show, however,

M. J. Cassidy

We examine consequences of the density matrix approach to quantum theory in the context of a model spacetime containing closed timelike curves and find that in general, an initially pure state will evolve in a nonlinear way to a mixed quantum state. CPT invariance and the implications of this nonlinearity for the statistical interpretation of quantum theory

Herbert Nachbagauer

We present a self-consistent calculation of the finite temperature effective potential for $λΦ^4$ theory in four dimensions using a composite operator effective action. We find that in a spontaneously broken theory not only the so-called daisy and superdaisy graphs contribute to the next-to-leading order thermal mass, but also resummed non-local diagrams are

Saburo Higuchi, Chigak Itoi, Shinsuke Nishigaki, Norisuke Sakai

Large-$N$ renormalization group equations for one- and two-matrix models are derived. The exact renormalization group equation involving infinitely many induced interactions can be rewritten in a form that has a finite number of coupling constants by taking account of reparametrization identities. Despite the nonlinearity of the equation, the location of fix

E. Stein, P. Gornicki, L. Mankiewicz, A. Schaefer

Using the framework of QCD sum rules we predict the twist-3 contribution to the second moment of the polarized nucleon structure function $g_2(x)$. As the relevant local operator depends explicitely on the gluon field, we employ a recently studied interpolating nucleon current which contains three quark field and one gluon field operator. Despite the fact th

R. J. Protheroe, T. Stanev, V. S. Berezinsky

We describe a calculation of electromagnetic cascading in radiation and matter in the early universe initiated by the decay of massive particles or by some other process. We have used a combination of Monte Carlo and numerical techniques which enables us to use exact cross sections, where known, for all the relevant processes. In cascades initiated after the

Y. Chen, H. Ohashi, M. Akiyama

The thermal lattice BGK model is a recently suggested numerical tool which aims to simulate thermohydrodynamic problems. We investigate the quality of the lattice BGK simulation by calculating the temperature profiles in the Couette flow under different Eckert and Mach numbers. A revised lower order model is proposed and the higher order model is proved once

H. W. Capel, F. W. Nijhoff

We discuss the canonical structure of a class of integrable quantum mappings, i.e. iterative canonical transformations that can be interpreted as a discrete dynamical system. As particular examples we consider quantum mappings associated with the lattice analogues of the KdV and MKdV equations. These mappings possess a non-ultralocal quantum Yang-Baxter stru

B. J. Cole, H. G. Miller, R. M. Quick

This comment re-examines the origin of structure seen in the computed specific heat of finite nuclei. In a recent paper, Civitarese and Schvellinger suggest that such structure is due to model-space truncation in the calculations. We reaffirm our conclusion that the structure is caused by a collective-to-non-collective phase transformation at low temperature

B. J. Cole, N. J. Davidson, H. G. Miller

A novel Information Theory based method for determining the density of states from prior information is presented. The energy dependence of the density of states is determined from the observed number of states per energy interval and model calculations suggest that the method is sufficiently reliable to calculate the thermal properties of nuclei over a reas

Jindřich Zapletal

We prove it consistent relative to ZFC that all nontrivial forcings of size $\aleph _1$ add a Cohen real.

Qi Feng, Thomas Jech

We study projective stationary sets. The Projective Stationary Reflection principle is the statement that every projective stationary set contains an increasing continuous $\in$--chain of length $ω_1$. We show that if Martin&#39;s Maximum holds, then the Projective Stationary Reflection Principle holds. Also it is equivalent to the Strong Reflection Principl

Thomas Jech

This paper describes some experiments involving the automated theorem-proving program OTTER in the system TRC of illative combinatory logic. We show how OTTER can be steered to find a contradiction in an inconsistent variant of TRC, and present some experimentally discovered identities in TRC.

S. Alexander Ridgway, Erick J. Weinberg

The stability of the magnetically charged Reissner-Nordstrom black hole solution is investigated in the context of a theory with massive charged vector mesons. By exploiting the spherical symmetry of the problem, the linear perturbations about the Reissner-Nordstrom solution can be decomposed into modes of definite angular momentum $J$. For each value of $J$

Maurice R. Kibler

The concept of a quantum algebra is made easy through the investigation of the prototype algebras $u_{qp}(2)$, $su_q(2)$ and $u_{qp}(1,1)$. The latter quantum algebras are introduced as deformations of the corresponding Lie algebras~; this is achieved in a simple way by means of $qp$-bosons. The Hopf algebraic structure of $u_{qp}(2)$ is also discussed. The

S. Elitzur, A. Giveon, E. Rabinovici, A. Schwimmer

A class of two-dimensional globally scale-invariant, but not conformally invariant, theories is obtained. These systems are identified in the process of discussing global and local scaling properties of models related by duality transformations, based on non-semisimple isometry groups. The construction of the dual partner of a given model is followed through

J. A. Adams, N. Tetradis

We consider a theory of a scalar one-component field $ϕ$ coupled to a scalar $N$-component field $χ$. Using large $N$ techiques we calculate the effective potential in the leading order in $1/N$. We show that this is equivalent to a resummation of an infinite subclass of graphs in perturbation theory, which involve fluctuations of the $χ$ field only. We stud

Q. P. Liu

\hspace{.2in}We consider the Darboux type transformations for the spectral problems of supersymmetric KdV systems. The supersymmetric analogies of Darboux and Darboux-Levi transformations are established for the spectral problems of Manin-Radul-Mathieu sKdV and Manin-Radul sKdV. Several Bäcklund transformations are derived for the MRM sKdV and MR sKdV system

Bum-Hoon Lee, Hyunsoo Min

We study the various quantum aspects of the $N=2$ supersymmetric Maxwell Chern-Simons vortex systems. The fermion zero modes around the vortices will give rise the degenerate states of vortices. We analyze the angular momentum of these zero modes and apply the result to get the supermultiplet structures of the vortex. The leading quantum correction to the ma

Z. Bern, L. Dixon, D. C. Dunbar, D. A. Kosower

We describe techniques that simplify the calculation of one-loop QCD amplitudes with many external legs, which are needed for next-to-leading-order (NLO) corrections to multi-jet processes. The constraints imposed by perturbative unitarity, collinear singularities and a supersymmetry-inspired organization of helicity amplitudes are particularly useful. Certa

Tatsu Takeuchi, Aaron K. Grant, Jonathan L. Rosner

We present a model--independent analysis of the $Z b \bar b$ vertex, with the aim of constraining contributions of new physics to the left- and right--handed couplings of the $b$. We find that the left--handed coupling of the $b$ is quite narrowly constrained by present data, but that the right--handed coupling is still largely unconstrained.

Fredrick I. Olness, Stephan T. Riemersma

We compare the results of the fixed-flavor scheme calculation of Laenen, Riemersma, Smith and van Neerven with the variable-flavor scheme calculation of Aivazis, Collins, Olness and Tung for neutral-current (photon-mediated) heavy-flavor (charm and bottom) production. We compare the structure function $F_2(x,Q^2)$ throughout phase space, and also analyze the

R. L. Thews

Production of heavy quark antiquark systems in high energy heavy ion collisions must involve relativistic momentum components in a quantum mechanical approach. If the color forces are screened in a deconfining medium, one can define the analog of a formation or separation time by an overlap integral in the nonrelativistic bound state rest frame. This time pa

Fredrick I. Olness, Stephan T. Riemersma

We compare the results of the fixed-flavor scheme calculation of Laenen, Riemersma, Smith and van Neerven with the variable-flavor scheme calculation of Aivazis, Collins, Olness and Tung for the case of neutral-current (photon-mediated) heavy-flavor (charm and bottom) production. Specifically, we examine the features of both calculations throughout phase spa

James B. Hartle

In usual quantum theory, the information available about a quantum system is defined in terms of the density matrix describing it on a spacelike surface. This definition must be generalized for extensions of quantum theory which do not have a notion of state on a spacelike surface. It must be generalized for the generalized quantum theories appropriate when

Jorge Pullin

Table of contents Editorial. Gravity News: Report on the APS topical group in gravitation, Beverly Berger. Research briefs: Gravitational microlensing and the search for dark matter, Bohdan Paczynski. Laboratory gravity: the G mystery, Riley Newman. LIGO project update, Stan Whitcomb. Conference Reports PASCOS &#39;94, Peter Saulson. The Vienna Meeting, P. A

R. Morf, N. d&#39;Ambrumenil

We propose a measure of the stability of composite fermions (CF&#39;s) at even-denominator Landau-level filling fractions. Assuming Landau-level mixing effects are not strong, we show that the CF liquid at $ν=2+1/2$ in the $n=1$ Landau level cannot exist and relate this to the absence of a hierarchy of incompressible states for filling fractions $2+1/3 < ν<

M. Franz, S. Teitel

We carry out MC studies of 2D superconducting networks, in an applied magnetic field, for square and honeycomb geometries. We consider both dilute systems (f=1/q) and systems near full frustration (f=1/2-1/q). For the dilute case (which models a film as q->infinity), we find two transitions: at T_c(f)~1/q there is a depinning transition from a pinned to a fl

W. Metzner, C. Castellani

The wave function of two fermions, repulsively interacting in the presence of a Fermi sea, is evaluated in detail. We consider large but finite systems in order to obtain an unabiguous picture of the two-particle correlations. As recently pointed out by Anderson, in two or lower dimensions the particles may be correlated even when situated on the Fermi surfa

Pietro Donatis, Roberto Iengo

We study the possible penetration of a static magnetic field in an idealized sample of many layers supporting a two dimensional charged chiral quantum fluid, to see whether there is a kind of Meissner effect. This is a non standard problem since the quantum fluid is incompressible having a gap in its spectrum. We find that the system shows an intermediate be

Arlin P. S. Crotts, Jill Bechtold, Yihu Fang, Robert C. Duncan

We present spectra of QSOs 1343+266 A B, covering Ly-beta to C~IV emission at 2Å~resolution, and find further evidence that this system is not gravitationally lensed. We see, however, a large number of Ly-alpha and some C~IV absorption features common to both spectra. The frequency of C~IV lines in common indicates that these absorbers have a radius close to

Jill Bechtold, Arlin P. S. Crotts, Robert C. Duncan, Yihu Fang

We have obtained spectroscopy of Q 1343+266 AB, a pair of quasars at redshift z = 2.03 with a projected separation of 9.5 arcseconds. This system is well-suited for probing the Ly-alpha forest, since the two component spectra show several Ly-alpha lines in common and several others not. Using Bayesian statistics, under the idealization of uniform-radius sphe

Marco Scodeggio, José M. Solanes, Riccardo Giovanelli, Martha P. Haynes

A total of 663 galaxies with known redshifts in a $6°\!\times 6°$ field centered on A2634, including 211 new measurements, are used to study the structure of this cluster and its surroundings. Two samples, ---one containing 200 galaxies within two degrees from the cluster center and a second, magnitude-limited, of 118 galaxies within the central half degree-

M. Plionis, R. Valdarnini

We derive the 1-point probability density function of the smoothed 3-D Abell-ACO cluster density field and we compare it with that of artificial cluster samples, generated as high peaks of a Gaussian field in such a way that they reproduce the low-order (2- and 3-point) correlation functions and the observed cluster selection functions. We find that both rea

Paul Meurer

We compute the number of rational quartics on a general Calabi-Yau hypersurface in weighted projective space P(2,1^4). The result agrees with the prediction made by mirror symmetry.

Michael Youssefmir, Bernardo Huberman, Tad Hogg

We present a dynamical theory of asset price bubbles that exhibits the appearance of bubbles and their subsequent crashes. We show that when speculative trends dominate over fundamental beliefs, bubbles form, leading to the growth of asset prices away from their fundamental value. This growth makes the system increasingly susceptible to any exogenous shock,

Shawn J. Kolitch

Solutions to flat space Friedmann-Robertson-Walker cosmologies in Brans-Dicke theory with a cosmological constant are investigated. The matter is modelled as a $γ$-law perfect fluid. The field equations are reduced from fourth order to second order through a change of variables, and the resulting two-dimensional system is analyzed using dynamical system theo

R. D. Benguria, M. C. Depassier

We give an integral variational characterization for the speed of fronts of the nonlinear diffusion equation $u_t = u_{xx} + f(u)$ with $f(0)=f(1)=0$, and $f>0$ in $(0,1)$, which permits, in principle, the calculation of the exact speed for arbitrary $f$.

Janos Polonyi

The running coupling constants are introduced in Quantum Mechanics and their evolution is described by the help of the renormalization group equation. The harmonic oscillator and the propagation on curved spaces are presented as examples. The hamiltonian and the lagrangian scaling relations are obtained. These evolution equations are used to construct low en

E. F. Bunn, D. Scott, M. White

The COBE detection of CMB anisotropies provides the best way of fixing the amplitude of fluctuations on the largest scales. This normalization is usually given for an n=1 spectrum, including only the anisotropy caused by the Sachs- Wolfe effect. This is certainly not a good approximation for a model containing any reasonable amount of baryonic matter. In fac

Mitsuko Abe, A. Nakamichi, T. Ueno

A topological version of four-dimensional (Euclidean) Einstein gravity which we propose regards anti-self-dual 2-forms and an anti-self-dual part of the frame connections as fundamental fields. The theory describes the moduli spaces of conformally self-dual Einstein manifolds for the non-zero cosmological constant case and Einstein-Kahlerian manifold with th

Sergei V. Ketov

The quantum BRST charges for the Bershadsky-Knizhnik orthogonal quasi-superconformal algebras are constructed. These two-dimensional superalgebras have the $N$-extended non-linearly realised supersymmetry and the $SO(N)$ internal symmetry. The BRST charge nilpotency conditions are shown to have a unique solution at $N>2$, namely, $N=4$ and $k=-2$, where $k$

Minos Axenides, Arne L. Larsen

We investigate the quantum nucleation of pairs of charged circular cosmic strings in de Sitter space. By including self-gravity we obtain the classical potential energy barrier and compute the quantum mechanical tunneling probability in the semiclassical approximation. We also discuss the classical evolution of charged circular strings after their nucleation

Jisuke Kubo, Myriam Mondragon, Nicholas D. Tracas, George Zoupanos

We study asymptotically non-free gauge theories and search for renormalization group invariant (i.e. technically natural) relations among the couplings which lead to successful gauge-Yukawa unification. To be definite, we consider a supersymmetric model based on $SU(4)\times SU(2)_{R}\times SU(2)_{L}$. It is found that among the couplings of the model, which

R. Sollacher

We present a method for extracting effective Lagrangians from QCD. The resulting effective Lagrangians are based on exact rewrites of cut-off QCD in terms of these new collective field degrees of freedom. These cut-off Lagrangians are thus ``effective&#39;&#39; in the sense that they explicitly contain some of the physical long-distance degrees of freedom fr

A. A. Deriglazov, A. V. Galajinsky

In the superspace $z^M = (x^μ,θ_R,θ_L)$ the global symmetries for $d$ = 10 superparticle model with kinetic terms both for Bose and Fermi variables are shown to form a superalgebra, which includes the Poincaré superalgebra as a subalgebra. The subalgebra is realized in the space of variables of the theory by a nonstandard way. The local version of this model

B. Jurco

A brief review of the construction and classifiaction of the bicovariant differential calculi on quantum groups is given.

R. B. Zhang

The Reshetikhin - Turaeve approach to topological invariants of three - manifolds is generalized to quantum supergroups. A general method for constructing three - manifold invariants is developed, which requires only the study of the eigenvalues of certain central elements of the quantum supergroup in irreducible representations. To illustrate how the method

S. Chernyshev, M. A. Nowak, I. Zahed

We analyze the correlation function of a meson with one heavy and one light quark in inverse powers of the heavy quark mass $m_Q$ using a succession of Foldy-Wouthuysen-type transformations prior to radiative corrections. We evaluate the correlator to order $m_Q^0$ in a random and dilute gas of instantons, using the planar approximation. We show, in leading

L. Lavoura

In a general two-scalar-doublet model without fermions, there is a unique source of CP violation, $ J_1 $, in the gauge interactions of the scalars. It arises in the mixing of the three neutral physical scalars $ X_1 $, $ X_2 $ and $ X_3 $. CP violation may be observed via different decay rates for $ X_1 \rightarrow H^+ W^- $ and $ X_1 \rightarrow H^- W^+ $

D. Zeppenfeld

Color singlet two gluon exchange provides a perturbative model for the pomeron. This mechanism is thought to explain the production of rapidity gaps in hard dijet events at the Tevatron. It is shown that in $qQ$ scattering via two gluon color singlet exchange the emission of soft gluons follows closely the pattern found for $t$-channel photon exchange. Gluon

J. Bartelski, S. Tatur

Starting from Martin, Roberts and Stirling fit for unpolarized deep inelastic structure functions and using the newest experimental data on spin asymmetries we get a fit which provides polarized quark distributions. We analyze the behaviour of such functions near $x$ equal to 1. The first moments of these distributions are also discussed. Our fit prefers com

Frank Close

Production of metastable charmonium states more massive than the $ψ(3685)$ is expected in models and could be the source of up to $50\%$ of the $ψ$ observed at large $p_T$ at the Tevatron.Narrow $2^{-+},2^{--} c\bar{c}$ are predicted at around 3.8GeV and radially excited $2^3P_{1,2}$ may also have suppressed hadronic widths making these states potentially ex

D. Semikoz, I. Tkachev

The process of condensation in the system of scalar Bosons with weak $λϕ^4$ interaction is considered. Boltzmann kinetic equation is solved numerically. Bose condensation proceeds in two stages: At the first stage condensate is still absent but there is non-zero inflow of particles towards $\vec{\bf p} = 0$ and the distribution function at $\vec{\bf p} = 0$

G. Valencia, S. Willenbrock

We study meson decays mediated by the heavy gauge bosons of the Pati-Salam model of quark-lepton unification. We consider the scenarios in which the tau lepton is associated with the third, second, and first generation of quarks. The most sensitive probes, depending on the scenario, are rare K, pi, and B decays.

V. V. Kiselev, A. K. Likhoded, M. V. Shevlyagin

The cross-section for the double charmed baryon production at a $B$-factory is estimated on the basis of the perturbative QCD calculations for the $c c$-diquark production as well as of the quark-hadron duality.

R. Barbieri, L. J. Hall

Using the Yukawa couplings of the minimal supersymmetric SU(5) model, the rates for $μ\to eγ$, $μ\to e$ conversion and $τ\to μγ$ are computed. For a selectron mass of 100 GeV, and without exploring the full parameter space, we find rates which are one order of magnitude beneath present experimental bounds. It is argued that these relatively large rates have

K. Kanaya, S. Kaya

By Monte Carlo simulation we study the critical exponents governing the transition of the three-dimensional classical O(4) Heisenberg model, which is considered to be in the same universality class as the finite-temperature QCD with massless two flavors. We use the single cluster algorithm and the histogram reweighting technique to obtain observables at the

Kevin Cahill, Gary Herling

We have applied a new gauge-invariant, noncompact, Monte Carlo method to simulate $U(1)$, $SU(2)$, and $SU(3)$ gauge theories on $8^4$ and $12^4$ lattices. The Creutz ratios of the Wilson loops agree with the exact results for $U(1)$ for $β\ge 1$ apart from a renormalization of the charge. The $SU(2)$ and $SU(3)$ Creutz ratios robustly display quark confinem

J. D. Brown, K. V. Kuchar

The coupling of the metric to an incoherent dust introduces into spacetime a privileged dynamical reference frame and time foliation. The comoving coordinates of the dust particles and the proper time along the dust worldlines become canonical coordinates in the phase space of the system. The Hamiltonian constraint can be resolved with respect to the momentu

Marco Cavaglia, Vittorio de Alfaro, Alexandre T. Filippov

We discuss how to fix the gauge in the canonical treatment of Lagrangians, with finite number of degrees of freedom, endowed with time reparametrization invariance. The motion can then be described by an effective Hamiltonian acting on the gauge shell canonical space. The system is then suited for quantization. We apply this treatment to the case of a Robert

S. Safra, M. Tennenholtz

This paper introduces a framework for Planning while Learning where an agent is given a goal to achieve in an environment whose behavior is only partially known to the agent. We discuss the tractability of various plan-design processes. We show that for a large natural class of Planning while Learning systems, a plan can be presented and verified in a reason

Michael R. Geller, Giovanni Vignale

We derive a general expression for the low-temperature current distribution in a two-dimensional electron gas, subjected to a perpendicular magnetic field and in a confining potential that varies slowly on the scale of the magnetic length l. The analysis is based on a self-consistent one-electron description, such as the Hartree or standard Kohn-Sham equatio

Yacov Kantor, Mehran Kardar

We consider polymers formed from a (quenched) random sequence of charged monomers of opposite signs. Such polymers, known as polyampholytes (PAs), are compact when completely neutral and expanded when highly charged. We examine the transition between the two regimes by Monte Carlo simulations, and by analogies to charged drops. We find that the overall exces

L. -H. Tang, M. Kardar, D. Dhar

We show that the critical behavior of a driven interface, depinned from quenched random impurities, depends on the isotropy of the medium. In anisotropic media the interface is pinned by a bounding (conducting) surface characteristic of a model of mixed diodes and resistors. Different universality classes describe depinning along a hard and a generic directi

Min-Chul Cha, H. A. Fertig

We report on the results of molecular dynamics simulation (MD) studies of the classical two-dimensional electron crystal in the presence disorder. Our study is motivated by recent experiments on this system in modulation doped semiconductor systems in very strong magnetic fields, where the magnetic length is much smaller than the average interelectron spacin

N. W. Evans

Microlensing maps -- that is, contours of equal numbers of events per $10^6$ source stars -- are provided for the inner Galaxy under two alternative hypotheses : (1) the bulge is an oblate axisymmetric spheroid or (2) the bulge is a prolate bar. Oblate spheroids yield a total of $\sim 12$ events per year per $10^6$ stars at Baade&#39;s Window ($\sim 15$ even

Andrew Gould

The transverse velocity of a spiral galaxy can be measured to an accuracy $\sim 60\,\kms$ by making parallax observations of quasars being microlensed by stars in the disk of the galaxy. To make the measurement, a quasar must be located behind the disk of the galaxy between about 1 and 2 scale lengths from the center. The quasar must then be monitored for mi