October 1999 arXiv papers

M. M. Sheikh-Jabbari

In this note we will show that the $Λ$ symmetry, namely the U(1) symmetry of the open string sigma model which relates the B-field and the U(1) gauge field of a brane to each other, is deformed to a noncommutative version in a constant B-field background.

M. A. Clayton, J. W. Moffat

A gravity theory is developed with the metric ${\hat g}_{μν}= {g}_{μν}+B\partial_μϕ\partial_νϕ$. In the present universe the additional contribution from the scalar field in the metric ${\hat g}_{μν}$ can generate an acceleration in the expansion of the universe, without negative pressure and with a zero cosmological constant. In this theory, gravitational w

Shinji Hirano

We propose a gauge invariant formulation of the exact renormalization group equation for nonsupersymmetric pure U(N) Yang-Mills theory, based on the construction by Tim Morris. In fact we show that our renormalization group equation amounts to a regularized version of the loop equation, thereby providing a direct relation between the exact renormalization gr

Irina Mocioiu, Robert Shrock

We calculate matter effects on neutrino oscillations relevant for long baseline neutrino oscillation experiments. In particular, we compare the results obtained with simplifying approximations for the density profile in the Earth versus results obtained with actual density profiles. We study the dependence of the oscillation signals on both $E/Δm^2_{atm.}$ a

M. Baldo, U. Lombardo, E. Saperstein, M. Zverev

The microscopic effective pairing interaction in the $^1S_0$-channel is investigated for two different values of the chemical potential $μ$ starting from the separable form of the Paris NN-potential. It is shown that, within a high accuracy, this effective interaction can be approximated by the off-shell free T-matrix taken at the negative energy $E=2μ$.

A. Ashikhmin, A. Barg, S. Litsyn

Polynomial, or Delsarte's, method in coding theory accounts for a variety of structural results on, and bounds on the size of, extremal configurations (codes and designs) in various metric spaces. In recent works of the authors the applicability of the method was extended to cover a wider range of problems in coding and information theory. In this paper

A. V. Efremov, O. V. Teryaev

The smallness of the deuteron tensor spin structure function is the necessary condition to extract neutron $g_1$ function neglecting the nuclear effects. The oscillating behavior of the quark tensor spin structure function leading to the zero first moment is shown to be the straightforward consequence of the factorization property and Lorentz covariance. For

Mikhail V. Feigel'man, Lev B. Ioffe, Vadim B. Geshkenbein, Gianni Blatter

We propose a new method to measure the coherence time of superconducting phase qubits based on the analysis of the magnetic-field dependent dc nonlinear Andreev current across a high-resistance tunnel contact between the qubit and a dirty metal wire and derive a quantitative relation between the subgap I-V characteristic and the internal correlation function

Fabrizio Brighenti, William G. Mathews

Anticipating forthcoming observations with the Chandra X-ray telescope, we describe the continuation of interstellar cooling flows deep into the cores of elliptical galaxies. Interstellar gas within about r = 50 parsecs from the massive black hole is heated to T > 1 keV and should be visible unless thermal heating is diluted by non-thermal pressure. Since ou

Yasuhiro Fujii, Miki Wadati

The generating functional of correlation functions for the XXZ spin chain is considered in the thermodynamic limit. We derive a system of integro-difference equations that prescribe this functional. On the basis of this system we establish the operator-valued Riemann-Hilbert problem for correlation functions of the XXZ spin chain.

Tarek Ibrahim, Pran Nath

We show that EDMs obey a simple approximate scaling under the transformation $m_0\to λm_0,m_{1/2}\to λm_{1/2}$ in the large $μ$ region when $μ$ itself obeys the same scaling, ie., $μ\to λμ$. In the scaling region the knowledge of a single point in the MSSM parameter space where the cancellation in the EDMs occur allows one to generate a trajectory in the $m_

E. Getzler, E. Looijenga

We give formulas for the Dolbeault numbers of \Mbar_{3,1}, using the first author's calculations of the weights of the cohomology of M_{2,2} and M_{2,3} and the second author's calculation of the weights of the cohomology of M_{3,1}.

Denis V. Juriev

This short article is devoted to the dynamics of controlled (and, therefore, open) systems. The internal forces, which appear only in the presence of external free controls and depend explicitely on them, are considered. Such interactive forces may be regarded as feedbacks generated in the system by the external free controls. In particular, one is able to i

Elso Drigo Filho, Regina Maria Ricotta

The Variational Method is applied within the context of Supersymmetric Quantum Mechanics to provide information about the energy and eigenfunction of the lowest levels of a Hamiltonian. The approach is illustrated by the case of the Morse potential applied to several diatomic molecules and the results are compared with stablished results.

F. Göhmann, V. E. Korepin

We derive a formula that expresses the local spin and field operators of fundamental graded models in terms of the elements of the monodromy matrix. This formula is a quantum analogue of the classical inverse scattering transform. It applies to fundamental spin chains, such as the XYZ chain, and to a number of important exactly solvable models of strongly co

B. Zheng

Recent progress in numerical study of the short-time critical dynamics is briefly reviewed.

Alan D. Sokal

The q-state Potts model can be defined on an arbitrary finite graph, and its partition function encodes much important information about that graph, including its chromatic polynomial, flow polynomial and reliability polynomial. The complex zeros of the Potts partition function are of interest both to statistical mechanicians and to combinatorists. I give a

Sergei Maslov

We introduce and study a simple model of a limit order-driven market. Traders in this model can either trade at the market price or place a limit order, i.e. an instruction to buy (sell) a certain amount of the stock if its price falls below (raises above) a predefined level. The choice between these two options is purely random (there are no strategies invo

L. Kaplan

We discuss recent developments in the study of quantum wavefunctions and transport in classically ergodic systems. Surprisingly, short-time classical dynamics leaves permanent imprints on long-time and stationary quantum behavior, which are absent from the long-time classical motion. These imprints can lead to quantum behavior on single-wavelength or single-

Amlan Biswas, M. Rajeswari, R. C. Srivastava, Y. H. Li

We present a study of the effect of biaxial strain on the electrical and magnetic properties of thin films of manganites. We observe that manganite films grown under biaxial compressive strain exhibit island growth morphology which leads to a non-uniform distribution of the strain. Transport and magnetic properties of these films suggest the coexistence of t

T. Lefort, L. Beaulieu, A. Botvina, D. Durand

Fragment kinetic energy spectra for reactions induced by 8.0 GeV/c $\rm{π^-}$ beams incident on a $\rm{^{197}}$Au target have been analyzed in order to deduce the possible existence and influence of thermal expansion. The average fragment kinetic energies are observed to increase systematically with fragment charge but are nearly independent of excitation en

M. R. Ahmady, F. A. Chishtie, V. Elias, T. G. Steele

We utilize asymptotic Pade-approximant methods to estimate the three-loop order MS bar-scheme coefficients within the inclusive semileptonic b to u decay rate for four and five active quark flavours. The estimates we obtain for the three renormalization-group-accessible coefficients within the three-loop contribution are all found to be within 5.1% of their

Mihail Mihailescu, Kyungho Oh, Radu Tatar

We consider the spectrum of open strings for non-BPS D-brane configuration in type II string theory on a Calabi-Yau threefold. In general, there is no degeneracy between bosonic and fermionic states. However we find special values for the moduli space of Calabi-Yau threefolds there are non-BPS brane configurations which have an exact degeneracy between boson

Nathan Berkovits

Sigma model actions are constructed for the Type II superstring compactified to four and six dimensional curved backgrounds which can contain non-vanishing Ramond-Ramond fields. These actions are N=2 worldsheet superconformally invariant and can be covariantly quantized preserving manifest spacetime supersymmetry. They are constructed using a hybrid version

R. Moessner, S. L. Sondhi, P. Chandra

We investigate the interplay of classical degeneracy and quantum dynamics in a range of periodic frustrated transverse field Ising systems at zero temperature. We find that such dynamics can lead to unusual ordered phases and phase transitions, or to a quantum spin liquid (cooperative paramagnetic) phase as in the triangular and kagome lattice antiferromagne

Philip C. Argyres, Ken Intriligator, Robert G. Leigh, Matthew J. Strassler

Four-dimensional N=1 supersymmetric gauge theories with two adjoints and a quartic superpotential are believed, from AdS/CFT duality, to have SL(2,Z) invariance. In this note we review an old, unpublished argument for this property, based solely on field theory. The technique involves a complexified flavor rotation which deforms an N=2 supersymmetric gauge t

A. Vogt

The behaviour of the quark coefficient functions in deep-inelastic scattering is investigated for large values of the Bjorken variable x. By combining results of soft-gluon resummation and fixed-order calculations, we determine the coefficients of the four leading large-x logarithms, alpha_s^k [{ln(1-x)}^{2k-l}/(1-x)]_+, l = 1, ...4, to all orders in the str

Paul S. Aspinwall, M. Ronen Plesser

We introduce a method of using the a dual type IIA string to compute alpha'-corrections to the moduli space of heterotic string compactifications. In particular we study the hypermultiplet moduli space of a heterotic string on a K3 surface. One application of this machinery shows that type IIB strings compactified on a Calabi-Yau space suffer from worlds

Fabio Riccioni

In this note we describe the most general coupling of {\it abelian} vector and tensor multiplets to six-dimensional $(1,0)$ supergravity. As was recently pointed out, it is of interest to consider more general Chern-Simons couplings to abelian vectors of the type $H^{r}=d B^{r}-1/2 c^{rab} A^{a}d A^{b}$, with $c^{r}$ matrices that may not be simultaneously d

William Arveson

A mathematical notion of interaction is introduced for noncommutative dynamical systems, i.e., for one parameter groups of *-automorphisms of $\Cal B(H)$ endowed with a certain causal structure. With any interaction there is a well-defined "state of the past" and a well-defined "state of the future". We describe the construction of many inter

Donam Youm

We relate various black hole solutions in the near-horizon region to black hole solutions in two-dimensional dilaton gravity theories in order to argue that thermodynamics of black holes in D>=4 can be effectively described by thermodynamics of black holes in two-dimensional dilaton gravity theories. We show that the Bekenstein-Hawking entropies of single-ch

Andrzej Krolak

We discuss several aspects of cosmic censorship hypothesis. There is evidence both in favor and against the hypothesis. On one hand one can prove that cosmic censorship holds in several special cases and on the other hand there is a number of special solutions of Einstein equations in which it is violated. One way to resolve cosmic censorship problem is to t

M. N. Achasov, S. E. Baru, K. I. Beloborodov, A. V. Berdyugin

The new data on $ρ,ω,ϕ$ radiative decays into $π^0γ,ηγ,η'γ$ from SND experiment at VEPP-2M $e^+e^-$ collider are presented.

Prot Pakonski

Many quantum systems may have the same classical limit. We argue that in the classical limit their traces do not necessarily converge one to another. The trace formula allows to express quantum traces by means of classical quantities as sums over periodic orbits of the classical system. To explain the lack of convergence of the traces we need the quantum cor

Detlev Buchholz, Rudolf Haag

We discuss the status and some perspectives of relativistic quantum physics.

Vito W. Scarola, Kwon Park, Jainendra K. Jain

A major obstacle toward a {\em quantitative} verification, by comparison to experiment, of the theory of the excitations of the fractional quantum Hall effect has been the lack of a proper understanding of disorder. We circumvent this problem by studying the {\em neutral} magneto-roton excitations, whose energy is expected to be largely insensitive to disord

G. Ortiz, A. A. Aligia

We elaborate on a geometric characterization of the electromagnetic properties of matter. A fundamental complex quantity, z_{L}, is introduced to study the localization properties of extended quantum systems. z_L, which allows us to discriminate between conducting and non-conducting thermodynamic phases, has an illuminating physical (and geometric) interpret

Tommy Ohlsson, Hakan Snellman

We derive analytic expressions for three flavor neutrino oscillations in the presence of matter in the plane wave approximation using the Cayley-Hamilton formalism. Especially, we calculate the time evolution operator in both flavor and mass bases. Furthermore, we find the transition probabilities, matter mass squared differences, and matter mixing angles al

Marc Chemtob, Grégory Moreau

The contribution from the R parity violating interactions in the associated production of a top quark with a charm antiquark is examined for high energy leptonic colliders. We concentrate on the reactions associated with the semileptonic top decay. A set of characteristic dynamical distributions for the signal events is evaluated and the results contrasted a

Artan Borici

I construct a Lanczos process on a large and sparse matrix and use the results of this iteration to compute the inverse square root of the same matrix. The algorithm is a stable version of an earlier proposal by the author. It can be used for problems related to the matrix sign and polar decomposition. The application here comes from the theory of chiral fer

J. Kluson

We construct unstable system D8-brane+D8-antibrane as a kink solution on world-volume of non-BPS D9-brane in Type IIA theory. Further we will make other checks confirming validity of our appro.

Christine C. Dantas, Andre L. B. Ribeiro, Hugo V. Capelato, Reinaldo R. de Carvalho

Motivated by present indirect evidences that galaxies are surrounded by dark matter halos, we investigate whether their physical properties can be described by a formulation of the virial theorem which explicitly takes into account the gravitational potential term representing the interaction of the dark halo with the barionic or luminous component. Our anal

St. Kolb, M. Hirsch, H. V. Klapdor-Kleingrothaus, O. Panella

Decays of sneutrinos are considered in the case that in the presence of lepton-number violation in the sneutrino sector the lighter tau-sneutrino is the Lightest Supersymmetric Particle and the Cold Dark Matter in the Universe. In such circumstances the signals from sparticle decays differ considerably from the ``standard'' case where the lightest ne

V. Bozza

Despite its mathematical complexity, the multiple gravitational lens can be studied in detail in every situation where a perturbative approach is possible. In this paper, we examine the caustics of a system with a lens very far from the others with respect to their Einstein radii, and a system where mutual distances between lenses are small compared to the E

S. Burger, K. Bongs, S. Dettmer, W. Ertmer

Dark solitons in cigar shaped Bose-Einstein condensates of Rubidium-87 are created by a phase imprinting method. Coherent and dissipative dynamics of the solitons has been observed.

Shin'ichirou Yoshida, Shigeyuki Karino, Shijun Yoshida, Yoshiharu Eriguchi

The first results of numerical analysis of classical r-modes of {\it rapidly} rotating compressible stellar models are reported. The full set of linear perturbation equations of rotating stars in Newtonian gravity are numerically solved without the slow rotation approximation. A critical curve of gravitational wave emission induced instability which restrict

Masayuki Matsuzaki

Spatial structure of Cooper pairs with quantum numbers color 3^*, I=J=L=S=0 in ud 2 flavor quark matter is studied by solving the gap equation and calculating the coherence length in full momentum range without the weak coupling approximation. Although the gap at the Fermi surface and the coherence length depend on density weakly, the shape of the r-space pa

Ying Jiang, Yishi Duan

We present a new generalized topological current in terms of the order parameter field $\vec ϕ$ to describe the arbitrary dimensional topological defects. By virtue of the $% ϕ$-mapping method, we show that the topological defects are generated from the zero points of the order parameter field $\vec ϕ$, and the topological charges of these topological defect

Andrey Tsiganov

For the Toda lattice and the Holt system we consider properties of canonical transformations of the extended phase space, which preserve integrability. The separated variables are invariant under change of the time. On the other hand, mapping of the time induces transformations of the action-angles variables and a shift of the generating function of the Bäck

Gert-Ludwig Ingold, Rodolfo A. Jalabert, Klaus Richter

We present a semiclassical study of level widths for a class of one-dimensional potentials in the presence of an ohmic environment. Employing an expression for the dipole matrix element in terms of the Fourier transform of the classical path we obtain the level widths within the Golden rule approximation. It is found that for potentials with an asymptotic po

Dima Mozyrsky

An exactly solvable model of a quantum spin interacting with a spin environment is considered. The interaction is chosen to be such that the state of the environment is conserved. The reduced density matrix of the spin is calculated for arbitrary coupling strength and arbitrary time. The stationary state of the spin is obtained explicitely in the $t \to \inf

Michael Ibison, Harold E. Puthoff, Scott R. Little

Recently Van Flandern concluded from astrophysical data that gravity propagates faster than light. We demonstrate that the data can be explained by current theory that does not permit superluminal speeds. We explain the origin of apparently instantaneous connections, first within EM, and then within strong-field GR.

M. E. Larraga, J. A. del Rio, Anita Mehta

We focus in this work on the study of traffic in open systems using a modified version of an existing cellular automaton model. We demonstrate that the open system is rather different from the closed system in its 'choice' of a unique steady-state density and velocity distribution, independently of the initial conditions, reminiscent of self-organise

A. B. Kukushkin, V. A. Rantsev-Kartinov

The evidences for tubular rigid-body structures are found in tokamak plasmas, which are similar to long-living filaments observed in a Z-pinch ([1] Kukushkin, Rantsev-Kartinov, Proc. 26-th EPS conf., http://epsppd.epfl.ch/cross/p2087.htm). These structures are suggested to be a "wild cables" produced by the channelling of EM energy pumped from the ex

G. Parzen

The presence of skew quadrupole fields will linearly couple the x and y motions. The x and y motions can then be written as the sum of two normal modes >. This paper presents analytical perturbation theory results for the tunes of the normal modes. The results for the normal mode tunes are first found correct to lowest order in the skew quadrupole fields. Th

G. V. Margagliotti, G. Pauli, L. Santi, S. Tessaro

The state dependent quenching mechanism of metastable antiprotonic He atoms by contaminants is suggested to explain existing experimental data. The effect of antiproton transfer from the antiprotonic He to noble gas contaminants is shown to play a significant role. Preliminary estimations have been done in the framework of the coupled channels model. The obt

C. W. Johnson, D. J. Dean

The Monte Carlo shell model is a powerful technique for computational nuclear structure. Only a certain class of nuclear interactions, however, such as pairing and quadrupole, are free of the numerical noise known as the sign problem.This paper presents sum rules that relate the sign problem to the J=0 pairing matrix elements, thus illuminating the extrapola

Horst Mueller, Jorge Piekarewicz

We study strangeness-changing response functions as an alternative description of hypernuclear structure. Hypernuclear states are treated in the same manner as any other conventional nuclear excitation that emerges from the response of the nuclear ground state to an external probe. The nuclear response is calculated using a random-phase approximation to an e

D. Bartz, Fl. Stancu

We study the nucleon-nucleon (NN) problem as a six-quark system in a nonrelativistic chiral constituent quark model where the Hamiltonian contains a linear confinement and a pseudoscalar meson (Goldstone boson) exchange interaction between the quarks. This interaction has a long range Yukawa-type part, depending on the mass of the exchanged meson and a short

P. Amore, A. De Pace

In this paper we study the modification of the properties of the nucleon in the nucleus within the quark-soliton model. This is a covariant, dynamical model, which provides a non-linear representation of the spontaneously broken SU(2)_L X SU(2)_R symmetry of QCD. The effects of the nuclear medium are accounted for by using the Wigner-Seitz approximation and

Gabor Zsolt Toth

We consider five-dimensional real linear spaces with a (otherwise well-known) linear action of the Galilei and the Poincare group on them, describe the geometry of these two spaces, and show, that these geometries comprise the notions of space-time, mass, momentum, force and physical dimensions in a natural way. In this way we geometrize the quantity of mass

Christof Kuelske

Can the joint measures of quenched disordered lattice spin models (with finite range) on the product of spin-space and disorder-space be represented as (suitably generalized) Gibbs measures of an ``annealed system''? - We prove that there is always a potential (depending on both spin and disorder variables) that converges absolutely on a set of full

Suemi Rodriguez-Romo

Following the method already developed for studying the actions of GL_q(2,C) on the Clifford algebra C(1,3) and its quantum invariants (Commun. in Algebra 27, 1843-1878(1999)), we study the action on C(1,3) of the quantum group GL_2 constructed by Dipper and Donkin. We are able of proving that there exists only two non-equivalent cases of actions with nontri

Victor G. Kac, Jose I. Liberati

We classify the quasifinite highest weight modules over a family of subalgebras W_{\infty}^{n} of the central extension W_{1+\infty} of the Lie algebra of differential operators on the circle consisting of operators of order \geq n. We classify the unitary quasifinite highest weight modules over W_{\infty}=W_{\infty}^{1} and realize them in terms of unitary

John Franks, David Richeson

In this paper we introduce filtration pairs for isolated invariant sets of continuous maps. We prove the existence of filtration pairs and show that, up to shift equivalence, the induced map on the corresponding pointed space is an invariant of the isolated invariant set. Moreover, the maps defining the shift equivalence can be chosen canonically. Lastly, we

Peter G. Casazza, Ole Christensen, A. J. E. M. Janssen

We present a comprehensive analysis of the convergence properties of the frame operators of Weyl-Heisenberg systems and shift-invariant systems, and relate these to the convergence of the Walnut representation. We give a deep analysis of necessary conditions and sufficient conditions for convergence of the frame operator. We show that symmetric, norm and unc

Peter G. Casazza

Thye theory of frames for a Hilbert space plays a fundamental role in signal processing, image processing, data compression, sampling theory and much more, as well as being a fruitful area of research in abstract mathematics. In this ``tutorial'' on abstract frame theory, we will try to point out the major directions of research in abstract frame the

R. M. Adin, L. Epstein, Y. Strassler

In this paper we completely classify the circulant weighing matrices of weight 16 and odd order. It turns out that the order must be an odd multiple of either 21 or 31. Up to equivalence, there are two distinct matrices in CW(31,16), one matrix in CW(21,16) and another one in CW(63,16) (not obtainable by Kronecker product from CW(21,16)). The classification

S. Carlip

This is a reply to a recent comment (hep-th/9910158) by Park and Ho on a paper (hep-th/9812013) that describes a derivation of black hole entropy from horizon conformal field theory. The criticism of Park and Ho is partially correct - the original paper did not give the complete surface term in the Hamiltonian - but it does not affect the conclusions, which

Edward Witten, S. -T. Yau

Let $M$ be a complete Einstein manifold of negative curvature, and assume that (as in the AdS/CFT correspondence) it has a Penrose compactification with a conformal boundary $N$ of positive scalar curvature. We show that under these conditions, $H_n(M;Z)=0$ and in particular $N$ must be connected. These results resolve some puzzles concerning the AdS/CFT cor

M. P. Infante, N. Sanchez

We present a minimal model for the Universe evolution fully extracted from effective String Theory. By linking this model with a minimal but well established observational information, we prove that it gives realistic predictions on early and current energy density and its results are compatible with General Relativity. Interestingly enough, the predicted cu

Jose A. Magpantay

The Parisi-Sourlas mechanism is exhibited in pure Yang-Mills theory. Using the new scalar degrees of freedom derived from the non-linear gauge condition, we show that the non-perturbative sector of Yang-Mills theory is equivalent to a 4D O(1,3) sigma model in a random field. We then show that the leading term of this equivalent theory is invariant under supe

Mu-In Park

The use of the physical variables in the fashion of Dirac in the three-dimensional Chern-Simons theories is presented. Our previous results are reinterpreted in a new aspect.

E. Martynov

A brief review on the Dipole Pomeron model is given. The model not only describes data on hadron-hadron interactions, but also allows to describe data on the proton structure function with a $Q^2$ independent intercept. Moreover the chosen Dipole Pomeron has an intercept equal to one and does not violate unitarity limit on the total elastic cross-section.

Vladimir Lugovoi

An algorithm of Monte Carlo code for the production of fast hadron leader in the (anti)proton-proton interaction by QCD process is discussed.

Fl. Stancu

We give a brief review of developments in the field of exotic hadrons formed of more than three quarks and/or antiquarks. In particular we discuss the stability of multiquark systems containing heavy flavours. We show that the gluon exchange model and the chiral constituent quark model based on Goldstone boson (pseudoscalar meson) exchange give entirely diff

Philip G. Ratcliffe

A summary is presented of the more theoretical aspects of the presentations made at Hyperon~99. In addition, some material is covered which was not presented at the symposium but which I feel is pertinent to the main theme of hyperons and/or, more in particular, to discussions conducted during the symposium.

N. N. Achasov

It is presented a critical consideration of all unusual properties of the scalar a_0(980) and f_0(980)-mesons in the four-quark, two-quark and molecular models. The arguments are adduced that the four-quark model is more preferable. It is discussed the complex of experiments that could finally resolve this issue.

Tanmoy Bhattacharya, Rajan Gupta, Weonjong Lee

We present a status report on the construction of the classical perfect action using the $ b=\sqrt{3} $ renormalization group transformation (RGT). We investigate finite volume corrections and map the locality of the fixed-point action by tuning the RGT parameter, $κ$. We compare results with the previous calculation for b=2 RGT.

Masako Iwasaki

We report the study of top-quark reconstruction in $e^+e^- \to t\bar{t}$ events at a 500 GeV linear collider using the LCD Fast Simulator. The final states of 6 jets as well as 4 jets and lepton are used. In order to reconstruct the jets, the performance of charged and neutral cluster separation are studied. We compare top-quark reconstruction for the LCD Sm

V. Halyo, P. Kim, E. R. Lee, I. T. Lee

We have carried out a direct search in bulk matter for free fractional electric charge elementary particles using the largest mass single sample ever studied - about 17.4 mg of silicone oil. The search used an improved and highly automated Millikan oil drop technique. No evidence for fractional charge particles was found. The concentration of particles with

Roberto Scipioni

We start from the pure Einstein-Hilbert action in Metric Affine Gravity, with the orthonormal metric. We get an effective Levi-Civita Dilaton gravity theory in which the Dilaton field is related to the scaling of the gravitational coupling. When the Weyl symmetry is broken the resulting Einstein-Hilbert term is equivalent to the Levi-Civita one, using the pr

Ulrich H. Gerlach

We exhibit a purely quantum mechanical carrier of the imprints of gravitation by identifying for a relativistic charge a property which (i) is independent of its mass and (ii) expresses the Poincare invariance of spacetime in the absence of gravitation. This carrier is a Klein-Gordon-equation-determined vector field given by the ``Planckian power'' a

Leonid B. Litinskii

In the Hopfield model the ability of the network to generalization is studied in the case of the network trained by one input image ({\it the standard}).

Arkady V. Krasheninnikov, Vladimir F. Elesin

Making use of the tight-binding Green's function technique, we have calculated the STM images of graphite with surface and sub-surface defects, while taking into account the relaxation of the lattice due to defects. We have demonstrated that two different physical mechanisms may result in the formation of hillocks in the STM images: buckling of the graph

Joel Koplik, Jayanth R. Banavar

We have studied the breakup and subsequent fluid flow in very thin films of partially wetting liquid on solid substrates, using molecular dynamics simulations. The liquid is made of short chain molecules interacting with Lennard-Jones interactions, and the solid is modeled as a clean crystal lattice whose atoms have thermal oscillations. Films below a critic

A. Bansil, M. Lindroos

We have carried out extensive first-principles angle-resolved photointensity (ARPES) simulations in Bi2212 wherein the photoemission process is modelled realistically by taking into account the full crystal wavefunctions of the initial and final states in the presence of the surface. The spectral weight of the ARPES feature associated with the CuO_2 plane ba

R. Egger, C. H. Mak

This article provides an introduction to the ideas behind the multilevel blocking (MLB) approach to the fermion sign problem in path-integral Monte Carlo simulations, and also gives a detailed discussion of MLB results for quantum dots. MLB can turn the exponential severity of the sign problem into an algebraic one, thereby enabling numerically exact studies

Muktish Acharyya, Abhik Basu, Rahul Pandit, Sriram Ramaswamy

We generalise the Driven Diffusive Lattice Gas (DDLG) model by using a combination of Kawasaki and Glauber dynamics. We find via Monte Carlo simulations and perturbation studies that the simplest possible generalisation of the equivalence of the canonical and grand-canonical ensembles, which holds in equilibrium, does not apply for this class of nonequilibri

A. S. Stepanenko, J. M. F. Gunn

We calculate the partition function of a gas of particles obeying Haldane exclusion statistics, using a definition of a Hilbert space having a `fractional dimension' and constructing appropriate coherent states. The fractional dimension is expressed though the form of the identity operator in the Hilbert space. We find that there many possible generalisa

Axel Gelfert, Wolfgang Nolting

The possibility of a magnetic phase transition in Heisenberg, Hubbard, and s-f (Kondo-lattice) films is investigated. It is shown that, for any finite temperature and any finite number of layers, the magnetization within every layer must vanish. Thus, the Mermin-Wagner theorem is extended to a variety of system geometries. We also comment on the microscopic

E. Goldobin, A. V. Ustinov

We study experimentally and theoretically the influence of phase-whirling (resistive) state in one junction of a two-fold Josephson stack on the fluxon motion in the other junction. In experiment, we measure the fluxon velocity versus current in one junction as a function of the state (Meissner or resistive) of the neighboring junction. The analysis, made fo

R. Hilfer, J. Widjajakusuma, B. Biswal

An approximate method to calculate dielectric response and relaxation functions for water saturated sedimentary rocks is tested for realistic threedimensional pore space images. The test is performed by comparing the prediction from the approximate method against the exact solution. The approximate method is based on image analysis and local porosity theory.

Krisztina Kadas, Georg Kern, Jurgen Hafner

We present ab initio local-density-functional electronic structure calculations for the (111) and (-1-1-1) surfaces of cubic BN. The energetically stable reconstructions, namely the N adatom, N3 triangle models on the (111), the (2x1), boron and nitrogen triangle patterns on the (-1-1-1) surface are investigated. Band structure and properties of the surface

S. R. Garner, Y. W. Rodriguez, Z. Schlesinger, B. Bucher

Infrared measurements are used to obtain conductivity as a function of temperature and frequency in YbInCu_4, which exhibits an isostructural transition to a mixed-valent state at T_v \simeq 42 K. In addition to a gradual loss of spectral weight with decreasing temperature extending up to 1.5 eV, sharp resonances appear in the mixed-valent state at 0 and 0.2

J. F. Wambaugh, C. Reichhardt, C. J. Olson, F. Marchesoni

We study stochastic transport of fluxons in superconductors by alternating current (AC) rectification. Our simulated system provides a fluxon pump, "lens", or fluxon "rectifier" because the applied electrical AC is transformed into a net DC motion of fluxons. Thermal fluctuations and the asymmetry of the ratchet channel walls induce this &#34

Tomohiro Sasamoto

The effect of a moving defect particle for the one-dimensional partially asymmetric simple exclusion process on a ring is considered. The current of the ordinary particles, the speed of the defect particle and the density profile of the ordinary particles are calculated exactly. The phase diagram for the correlation length is identified. As a byproduct, the

Karen Hallberg

The Density Matrix Renormalization Group (DMRG) has become a powerful numerical method that can be applied to low-dimensional strongly correlated fermionic and bosonic systems. It allows for a very precise calculation of static, dynamic and thermodynamic properties. Its field of applicability has now extended beyond Condensed Matter, and is successfully used

Awadhesh Prasad, Ramakrishna Ramaswamy

Upon addition of noise, chaotic motion in low-dimensional dynamical systems can sometimes be transformed into nonchaotic dynamics: namely, the largest Lyapunov exponent can be made nonpositive. We study this phenomenon in model systems with a view to understanding the circumstances when such behaviour is possible. This technique for inducing ``order'&#39

U. Oberlack, U. Wessolowski, R. Diehl, K. Bennett

The Wolf-Rayet binary system gamma^2 Vel (WR 11} is the closest known Wolf-Rayet (WR) star. Recently, its distance has been redetermined by parallax measurements with the HIPPARCOS astrometric satellite yielding 258^{+41}_{-31} pc, significantly lower than previous estimates (300 -- 450 pc). Wolf-Rayet stars have been proposed as a major source of the Galact