December 1998 arXiv papers

K. S. Babu, Jogesh C. Pati, Frank Wilczek

Within the framework of unified gauge models, interactions responsible for neutrino masses can also provide mechanisms for nucleon instability. We discuss their implications concretely in the light of recent results on neutrino oscillation from the SuperKamiokande collaboration. We construct a predictive SO(10)-based framework that describes the masses and m

I. A. Zaliznyak, C. Broholm, M. Kibune, M. Nohara

Using magnetic neutron scattering we characterize an unusual low temperature phase in orthorhombic SrCuO2. The material contains zigzag spin ladders formed by pairs of S=1/2 chains (J=180 meV) coupled through a weak frustrated interaction |J&#39;|<0.1J. At T<Tc1=5.0(4)K an elastic peak develops in a gapless magnetic excitation spectrum indicating spin freezi

Guenter Nimtz

It recently has been demonstrated that signals conveyed by evanescent modes can travel faster than light. In this report some special features of signals are introduced and investigated, for instance the fundamental property that signals are frequency band limited. Evanescent modes are characterized by extraordinary properties: Their energy is {\it negative}

Paolo Salucci, Charu Ratnam, Pierluigi Monaco, Luigi Danese

We use rotation curve kinematics of 1000 spiral galaxies to investigate if these galaxies could host BH (Black Hole) remnants that once powered the QSO phenomenon. The rotation curves of both early and late-type spirals are used to place upper limits on the BH mass. We find that the central objects in spirals are 10-100 times less massive than those detected

A. B. Lahanas, V. C. Spanos, Vasilios Zarikas

We discuss the features of a two-Higgs doublet model exhibiting a two stage phase transition. At finite temperatures electric charge violating stationary points are developed. In conjunction with {\em CP} violation in the Higgs or the Yukawa sector, the phase transition to the charge conserving vacuum, generates a net charge asymmetry $ΔQ$, in the presence o

Juan Garcia-Bellido, Alexander Kusenko

Shock waves in cold nuclear matter, e.g. those induced by a collision of two neutron stars, can generate a large number of gamma photons via parametric resonance. We study the resonant production of gamma rays inside a shocked neutron star and discuss the possible astrophysical consequences of this phenomenon.

B. M. Zupnik

We consider D-dimensional supersymmetric gauge theories with 8 supercharges (D<6,$~\mathcal{N}=8$) in the framework of harmonic superspaces. The effective Abelian low-energy action for D=5 contains the free and Chern-Simons terms. Effective $\mathcal{N}=8$ superfield actions for D<4 can be written in terms of the superpotentials satisfying the superfield con

A. Knigavko, B. Rosenstein

Topological analysis of nearly SO(3)_{spin} symmetric Ginzburg--Landau theory, proposed for UPt$_{3}$ by Machida et al, shows that there exists a new class of solutions carrying two units of magnetic flux: the magnetic skyrmion. These solutions do not have singular core like Abrikosov vortices and at low magnetic fields they become lighter for strongly type

Sin Kyu Kang, Jihn E. Kim, Jae Sik Lee

The neutral current effects of the future high statistics atmospheric neutrino data can be used to distinguish the mechanisms between a $ν_μ$ oscillation to a tau neutrino or to a sterile neutrino. However, if neutrinos possess large diagonal and/or transition magnetic moments, the neutrino magnetic moments can contribute to the neutral current effects which

Sechul Oh

We first present a model-independent analysis using flavor SU(3) symmetry with SU(3) breaking effects in $B$ decays to two charmless vector mesons ($VV$) in the final state. In order to bridge the flavor SU(3) symmetry approach and the factorization approach in $B \to VV$ decays, we explicitly show how to translate each SU(3) amplitude into a corresponding a

Jae Dong Noh, Hyunggyu Park, Marcel den Nijs

We point out how geometric features affect the scaling properties of non-equilibrium dynamic processes, by a model for surface growth where particles can deposit and evaporate only in dimer form, but dissociate on the surface. Pinning valleys (hill tops) develop spontaneously and the surface facets for all growth (evaporation) biases. More intriguingly, the

V. Bazhanov, S. Lukyanov, A. Zamolodchikov

Relation between the vacuum eigenvalues of CFT Q-operators and spectral determinants of one-dimensional Schroedinger operator with homogeneous potential, recently conjectured by Dorey and Tateo for special value of Virasoro vacuum parameter p, is proven to hold, with suitable modification of the Schroedinger operator, for all values of p.

J. Merino, Ross H. McKenzie, J. B. Marston, C. H. Chung

We consider the effect of quantum spin fluctuations on the ground state properties of the Heisenberg antiferromagnet on an anisotropic triangular lattice using linear spin-wave theory. This model should describe the magnetic properties of the insulating phase of the kappa-(BEDT-TTF)_2 X family of superconducting molecular crystals. The ground state energy, t

Adan Cabello

I show a situation of multiparticle entanglement which cannot be explained in the framework of an interpretation of quantum mechanics recently proposed by Mermin. This interpretation is based on the assumption that correlations between subsystems of an individual isolated composed quantum system are real objective local properties of that system.

Ruggero Maria Santilli

We review the recent experimental evidence on arbitrary values of the speed of light within physical media (interior dynamical problems); we recall that classical (operator) theories with speeds of light different than that in vacuum are noncanonically (nonunitarily) related to the special relativity, thus losing the original invariant character with consequ

J. V. Kadeisvili

We review the origin of the physical consistency of the Lorentz- Poincaré symmetry. We outline seemingly catastrophic physical inconsistencies recently identified for noncanonical-nonunitary generalized theories defined on conventional spaces over conventional fields. We review Santilli&#39;s isotopic lifting of the Lorentz-Poincaré symmetry, by proving its

W. C. Haxton

Nuclei are powerful laboratories for studying fundamental symmetries because they filter and enhance specific interactions. I discuss four examples --- hadronic parity violation, atomic electric dipole moments, precision $β$ decay tests, and nuclear tests of neutrino masses --- to illustrate some of the progress that has been made in the past few years.

Guang-han Wu, Jia-Lun Ping, Li-jian Teng, Fan Wang

We apply the quark delocalization and color screening model to nucleon-baryon scattering. A semi-quantitative fit to N-N, N-Lambda and N-Sigma phase shifts and scattering cross sections is obtained without invoking meson exchange. Quarks delocalize reasonably in all of the different flavor channels to induce effective nucleon-baryon interactions with both a

C. Ciofi degli Atti, D. Faralli, G. B. West

The basic approximations leading to non-relativistic and relativistic nuclear y and x scaling are recalled. The general and systematic features of y-scaling structure functions are pointed out, and a recently proposed novel approach to y-scaling, based on a global scaling variable, y_G, which incorporates the effect of the momentum dependence of the nucleon

Endre Csáki, Wolfgang König, Zhan Shi

For one-dimensional simple random walk in a general i.i.d. scenery and its limiting process we construct a coupling with explicit rate of approximation extending a recent result for Gaussian sceneries due to Khoshnevisan and Lewis. Furthermore we explicity identify the constant in the law of iterated logarithm.

Jeremy Kahn

Let $f(z) = z^2 + c$ be a quadratic polynomial, with c in the Mandelbrot set. Assume further that both fixed points of f are repelling, and that f is not renormalizable. Then we prove that the Julia set J of f is holomorphically removable in the sense that every homeomorphism of the complex plane to itself that is conformal off of J is in fact conformal on t

Charles F. Doran

Motivated by a conjecture of Lian and Yau concerning the mirror map in string theory, we determine when the mirror map q-series of certain elliptic curve and K3 surface families are Hauptmoduln (genus zero modular functions). Our geometric criterion for modularity characterizes orbifold uniformization properties of their Picard-Fuchs equations, effectively d

J. M. Evans, M. R. Gaberdiel, M. J. Perry

A brief review of string theory on group manifolds is given, and comparisons are then drawn between Minkowski space, SU(2), and SU(1,1) = AdS_3. The proof of the no-ghost theorem is outlined, assuming a certain restriction on the representation content for bosonic and fermionic strings on SU(1,1). Some possible connections with the AdS/CFT correspondence are

A. Gorsky

We suggest that RG flows in the N=2 SUSY YM theories are governed by the pair of the integrable systems. The main dynamical ingredient amounts from the interaction of the small size instantons with the regulator degrees of freedom. The relation with the bulk/boundary correspondence is discussed.

Soo-Young lee, Hungsoo Kim, D. K. Park, Chang Soo Park

A general condition for sharp transition of decay rate from quantum to thermal regimes is derived in dissipative tunneling models when position dependent mass is involved. It is shown that the effect of dissipation in general changes the order of the phase transition. Especially, for the models with constant mass the Ohmic dissipation enlarges the range of p

Jonathan L. Rosner

Some of the motivations for quark and lepton compositeness, and some problems associated with present schemes, are noted. One model is discussed in which quarks and leptons are taken as composites of spin-1/2 fermions $F$ with charges $\pm 1/2$ and spinless bosons $\bar S$ with charges 1/6 and -1/2.

Maria Krawczyk

The Higgs sector of the Standard Model and of the Two Higgs Doublet Extensions of SM, MSSM and the general 2HDM, can be tested in processes involving photons. A short review of the corresponding results is presented.

Juan Garcia-Bellido, Jaume Garriga, Xavier Montes

Quasiopenness seems to be generic to multi-field models of single-bubble open inflation. Instead of producing infinite open universes, these models actually produce an ensemble of very large but finite inflating islands. In this paper we study the possible constraints from CMB anisotropies on existing models of open inflation. The effect of supercurvature an

S. A. Kulagin

We discuss effect of nuclear shadowing in neutrino deep-inelastic scattering in terms of non perturbative parton model. We found that for small Bjorken $x$ and large $Q^2$ the structure function $F_3$ is shadowed in nuclei about two times as stronger as $F_2$. The underlying reason and phenomenological aspects of this observation are discussed.

Walter J. Wild

We develop a correspondence between arbitrary tensors and matrices based on the use of Kronecker products and associated identities. Utilizing the rules of matrix differentiation we derive the vacuum Einstein field equations as a differential-matrix equation. This formulation may facilitate their efficient use in numerical relativistic models.

Bertrand Duplantier

We consider in two dimensions the most general star-shaped copolymer, mixing random (RW) or self-avoiding walks (SAW) with specific interactions thereof. Its exact bulk or boundary conformal scaling dimensions in the plane are all derived from an algebraic structure existing on a random lattice (2D quantum gravity). The multifractal dimensions of the harmoni

B. Skoric, A. M. M. Pruisken

We derive, from first principles, the complete Luttinger liquid theory of abelian quantum Hall edge states. This theory includes the effects of disorder and Coulomb interactions as well as the coupling to external electromagnetic fields. We introduce a theory of spatially separated (individually conserved) edge modes, find an enlarged dual symmetry and obtai

M. L. Povinelli, S. N. Coppersmith, L. P. Kadanoff, S. R. Nagel

We investigate a nonlinear dynamical system which ``remembers&#39;&#39; preselected values of a system parameter. The deterministic version of the system can encode many parameter values during a transient period, but in the limit of long times, almost all of them are forgotten. Here we show that a certain type of stochastic noise can stabilize multiple memo

V. N. Plechko

We review some aspects of the fermionic interpretation of the two-dimensional Ising model. The use is made of the notion of the integral over the anticommuting Grassmann variables. For simple and more complicated 2D Ising lattices, the partition function can be expressed as a fermionic Gaussian integral. Equivalently, the 2D Ising model can be reformulated a

S. Mukherjee, P. Raychaudhuri, A. K. Nigam

We have studied the critical behaviour in $La_{0.5}Sr_{0.5}CoO_{3}$ near the paramagnetic-ferromagnetic transition temperature. We have analysed our dc magnetisation data near the transition temperature with the help of modified Arrott plots, Kouvel-Fisher method. We have determined the critical temperature $T_c$ and the critical exponents, $β$ and $γ$. With

J. E. Bunder, Ross H. McKenzie

We present some exact results for the effect of disorder on the critical properties of an anisotropic XY spin chain in a transverse field. The continuum limit of the corresponding fermion model is taken and in various cases results in a Dirac equation with a random mass. Exact analytic techniques can then be used to evaluate the density of states and the loc

David Ruelle

This paper reviews various applications of the theory of smooth dynamical systems to conceptual problems of nonequilibrium statistical mechanics. We adopt a new point of view which has emerged progressively in recent years, and which takes seriously into account the chaotic character of the microscopic time evolution. The emphasis is on nonequilibrium steady

D. V. Bisikalo, A. A. Boyarchuk, O. A. Kuznetsov, V. M. Chechetkin

We present the results of three-dimensional numerical simulations of mass transfer in semi-detached binary systems in which the mass-losing star is rotating. The cases of aligned and misaligned non-synchronous rotation of the donor star are considered; the resulting flow patterns are compared to the synchronous case. The main properties of the flow, such as

Yūichi Chikashige, Jun-ichi Kamoshita

We propose a formula for flux of extremely high energy cosmic rays (EHECR) through decay of superheavy particles. It is shown that EHECR spectrum reported by AGASA is reproduced by the formula. The presence of EHECR suggests, according to this approach, the existence of superheavy particles with mass of about $7 \times 10^{11}$GeV and the lifetime of about $

S. B. Popov, D. Yu. Konenkov

We studied possible evolution of the rotational period and the magnetic field of the X-ray source RX J0720.4-3125 assuming this source to be an isolated neutron star accreting from the interstellar medium. Magnetic field of the source is estimated to be $10^6 - 10^9$ Gs (most probably $\approx 2\cdot 10^8$ Gs), and it is difficult to explain the observable r

M. A. Clayton, J. W. Moffat

A dynamical model for varying light velocity in cosmology is developed, based on the idea that there are two metrics in spacetime. One metric $g_{μν}$ describes the standard gravitational vacuum, and the other ${\hat g}_{μν} =g_{μν}+βψ_μψ_ν$ describes the geometry through which matter fields propagate. Matter propagating causally with respect to $\hat{g}_{μν

P. Meszaros

The discovery of X-ray, optical and radio afterglows of GRBs provides an important tool for understanding these sources. Most current models envisage GRB as arising in a cataclysmic stellar event leading to a relativistically expanding fireball, where particle acceleration at shocks lead to nonthermal radiation. The predictions of this scenario are in substa

W. Hofstetter, S. Kehrein

The single channel Anderson impurity model is a standard model for the description of magnetic impurities in metallic systems. Usually, the bandwidth represents the largest energy scale of the problem. In this paper, we analyze the limit of a narrow band, which is relevant for the Mott-Hubbard transition in infinite dimensions. For the symmetric model we dis

A. Lanzara, N. L. Saini, A. Bianconi, Guo-meng Zhao

Recently a growing number of experiments have provided indications of the key role of polarons (composite particles formed by a charge strongly coupled with a local lattice deformation) in doped perovskites, hosting colossal magnetoresistance (CMR) and high Tc superconductivity. While the role of polarons is generally recognized in manganites due to the larg

P. K. Mitter, B. Scoppola

We propose to study the infrared behaviour of polymerised (or tethered) random manifolds of dimension D interacting via an exclusion condition with a fixed impurity in d-dimensional Euclidean space in which the manifold is embedded. We prove rigorously, via methods of Wilson&#39;s renormalization group, the convergence to a non Gaussian fixed point for suita

G. Cvetic, C. S. Kim, C. W. Kim

We investigate possibilities for detecting heavy Majorana neutrinos ($N$&#39;s) in $e^+e^-$ at LEP200 and future Linear Colliders. We concentrate on the processes where the pairs of intermediate heavy $N$&#39;s produce a clear signal of total lepton number violation ($e^+e^- \to NN \to W^+l^-W^+l^{\prime -}$). Such a signal is not possible if the heavy neutr

N. Gov, E. Polturak

We propose a model to treat the local motion of atoms in solid $^{4}$He as a local mode. In this model, the solid is assumed to be described by the Self Consistent Harmonic approximation, combined with an array of local modes. We show that in the bcc phase the atomic local motion is highly directional and correlated, while in the hcp phase there is no such c

D. Belitz, T. R. Kirkpatrick, Thomas Vojta

It is shown that the phase transition in low-T_c clean itinerant ferromagnets is generically of first order, due to correlation effects that lead to a nonanalytic term in the free energy. A tricritical point separates the line of first order transitions from Heisenberg critical behavior at higher temperatures. Sufficiently strong quenched disorder suppresses

Ulf Larsen

A complete, non-demolition procedure is established for measuring multi-qubit entangled states, such as the Bell-states and the GHZ-states, which is essential in certain processes of quantum communication, computation, and teleportation. No interaction between the individual parts of the entangled system, nor with any environment is required. A small probe (

Peng Zhou, S. Swain

It is shown that 100% squeezed output can be produced in the resonance fluorescence from a coherently driven two-level atom interacting with a squeezed vacuum. This is only possible for $N=1/8$ squeezed input, and is associated with a pure atomic state, i.e., a completely polarized state. The quadrature for which optimal squeezing occurs depends on the squee

Peng Zhou, Mao-Fa Fang, Qing-Ping Zhou, Gao-Xiang Li

The effect of the laser linewidth on the resonance fluorescence spectrum of a two-level atom is revisited. The novel spectral features, such as hole-burning and dispersive profiles at line centre of the fluorescence spectrum are predicted when the laser linewidth is much greater than its intensity. The unique features result from quantum interference between

Sergei M. Kopeikin, Vladimir A. Potapov

Millisecond and binary pulsars are the most stable natural frequency standards which admits to introduce modified versions of universal and ephemeris time scales based correspondingly on the intrinsic rotation of pulsar and on its orbital motion around barycenter of a binary system. Measured stability of these time scales depends on numerous physical phenome

E. O. Steinborn, H. H. H. Homeier, I. Ema, R. Lopez

A program for molecular calculations with B functions is reported and its performance is analyzed. All the one- and two-center integrals, and the three-center nuclear attraction integrals are computed by direct procedures, using previously developed algorithms. The three- and four-center electron repulsion integrals are computed by means of Gaussian expansio

A. Zabrodin

We give two &#34;complementary&#34; descriptions of the curve $Γ$ parametrizing double-Bloch solutions to the difference analogue of the Lamé equation. The curve depends on a positive integer number $\ell$ and two continuous parameters: the &#34;lattice spacing&#34; $η$ and the modular parameter $τ$. Apart from being a covering of the elliptic curve with the

Peter G. Casazza, N. J. Nielsen

In this paper we first show that if $X$ is a Banach space and $α$ is a left invariant crossnorm on $\ell_\infty\otimes X$, then there is a Banach lattice $L$ and an isometric embedding $J$ of $X$ into $L$, so that $I\otimes J$ becomes an isometry of $\ell_\infty\otimes_αX$ onto $\ell_\infty\otimes_m J(X)$. Here $I$ denotes the identity operator on $\ell_\inf

Peter G. Casazza, Ole Christensen

A Weyl-Heisenberg frame for L^2(R) is a frame consisting of translates and modulates of a fixed function. In this paper we give necessary and sufficient conditions for this family to form a tight WH-frame. This allows us to write down explicitly all functions g for which all translates and modulates of g form an orthonormal basis for L^2(R). There are a numb

Maxim Kontsevich, Alexander Rosenberg

We make an attempt to develop &#34;noncommutative algebraic geometry&#34; in which noncommutative affine schemes are in one-to-one correspondence with associative algebras. In the first part we discuss various aspects of smoothness in affine noncommutative algebraic geometry. The main example for us is the noncommutative affine space. The algebra of function

Patricio Gaete

The calculation of the interaction energy in pure QED and Maxwell-Chern-Simons gauge theory is re-examined by exploiting the path dependence of the gauge-invariant variables formalism. In particular, we consider a spacelike straight line which leads to the Poincaré gauge. Subtleties related to the problem of exhibiting explicitly the interaction energies are

Olaf Lechtenfeld, Boris Zupnik

We discuss alternative descriptions of four-dimensional self-dual Yang-Mills fields in harmonic space with additional commuting spinor coordinates. In particular, the linear analyticity equation and nonlinear covariant harmonic-field equations are studied. A covariant harmonic field can be treated as an infinite set of ordinary four-dimensional fields with h

C. Saclioglu

A product of two Riemann surfaces of genuses p_1 and p_2 solves the Seiberg-Witten monopole equations for a constant Weyl spinor that represents a monopole condensate. Self-dual electromagnetic fields require p_1=p_2=p and provide a solution of the euclidean Einstein-Maxwell-Dirac equations with p-1 magnetic vortices in one surface and the same number of ele

V. A. Smirnov, E. R. Rakhmetov

General prescriptions for evaluation of coefficients at arbitrary powers and logarithms in the asymptotic expansion of Feynman diagrams in the Sudakov limit are discussed and illustrated by two-loop examples. Peculiarities connected with evaluation of individual terms of the expansion, in particular, the introduction of auxiliary analytic regularization, are

V. A. Bednyakov, V. B. Brudanin, S. G. Kovalenko, Ts. D. Vylov

We analyze constraints on the parameters of the R-parity violating supersymmetry which can be extracted from non-observation of the neutrinoless nuclear double beta decay ($0νββ$) at a given half-life lower bound. Our analysis covers a large class of phenomenologically viable R-parity violating SUSY models. We introduce special characteristics: the SUSY sens

V. P. Petrov, G. S. Sharov

For the linear baryon string model with three massive points (three quarks) connected sequentially by the relativistic strings the initial-boundary value problem is stated and solved in general. This problem implies defining a classical motion of the system on the base of given initial position and initial velocities of string points. The given solution work

Wolfgang Lucha, F. F. Schoberl

In quantum theory, bound states are described by eigenvalue equations, which usually cannot be solved exactly. However, some simple general theorems allow to derive rigorous statements about the corresponding solutions, that is, energy levels and wave functions. These theorems are applied to the prototype of all relativistic wave equations, the spinless Salp

Mario Franz, Hyun-Chul Kim, Klaus Goeke

We present the recent investigation of the $ΔS = 1$ effective weak chiral Lagrangian within the framework of the instanton-induced chiral quark model. Starting from the effective four-quark operators, we derive the effective weak chiral action by integrating out the constituent quark fields. Employing the derivative expansion, we obtain the effective weak ch

M. Boonekamp, A. De Roeck, C. Royon, S. Wallon

The total $γ^*γ^*$ cross-section is derived in the Leading Order QCD dipole picture of BFKL dynamics, and compared with the one from 2-gluon exchange. The Double Leading Logarithm approximation of the DGLAP cross-section is found to be small in the phase space studied. Cross sections are calculated for realistic data samples at the $e^+e^-$ collider LEP and

A. V. Efremov, O. G. Smirnova, L. G. Tkatchev

The first probe of the correlation of the T-odd one-particle fragmentation function responsible for the left--right asymmetry of fragmentation of a transversely polarized quark and an antiquark is done by using the 1991-95 DELPHI data for $Z\to 2$ jet decay. Integrated over the fraction of longitudinal and transversal momenta, this correlation is of 2.5 ppm

S. Eidelman, F. Jegerlehner, A. L. Kataev, O. Veretin

Based on the compilation of the available e^+e^- data, we present a non-perturbative estimation of the Adler function derived from the electromagnetic current correlator, and compare it with theoretical predictions from perturbative QCD (pQCD). The comparison is presented for the Euclidean region where pQCD is supposed to work best. We emphasize that such a

Ken Sasaki, Tsuneo Uematsu

Polarized photon structure can be studied in the future polarized $e^{+}e^{-}$ colliding-beam experiments. We investigate the spin-dependent structure function of the virtual photon $g_1^γ(x,Q^2,P^2)$, in perturbative QCD for $Λ^2 \ll P^2 \ll Q^2$, where $-Q^2$ ($-P^2$) is the mass squared of the probe (target) photon. The analysis is performed to next-to-le

Mohammad Nouri-Zonoz, Donald Lynden-Bell

Using the fact that the null geodesics in NUT space lie on spatial cones, we consider the gravomagnetic lens effect on light rays passing a NUT deflector. We show that this effect changes the observed shape, size and orientation of a source. Compared to the Schwarzschild lens, there is an extra shear (a differential twist around the lens axis) due to the gra

A. Feoli, S. Rampone

We discuss the Carter&#39;s formula about the mankind evolution probability following the derivation proposed by Barrow and Tipler. We stress the relation between the existence of billions of galaxies and the evolution of at least one intelligent life, whose living time is not trivial, all over the Universe. We show that the existence probability and the lif

Mark D. Roberts

In general relativity g_ab;c=0 implies that the wave equation (\Box^2-M)g_ab=0 always has M=0. If the underlying geometry is generalized to include non-metricity this incurs M \neq 0, and the above wave equation can be rewritten as M(x)+\td{\na}_a Q_.^a+(\ep+\fr{d}{2}-2)Q_a Q_.^a=0, where \ep=0, 1, 2, or 3, d is the dimension of the spacetime, and Q is the o

Mihaela Time

A static axisymmetric solution with an additional cylindrical symmetry is considered and that the matter consists in a cosmological and a dust term.

Massimo Rontani, Fausto Rossi, Franca Manghi, Elisa Molinari

We study the energy spectra of small three-dimensional (3D) and two-dimensional (2D) semiconductor quantum dots through different theoretical approaches (single-site Hubbard and Hartree-Fock hamiltonians); in the smallest dots we also compare with exact results. We find that purely 2D models often lead to an inadequate description of the Coulomb interaction

V. I. Tsebro, O. E. Omel&#39;yanovskii, V. V. Kapaev, Yu. V. Kopaev

The giant transverse magnetoresistance is observed in the case of photoinduced nonequilibrium carriers in an asymmetric undoped system of three GaAs/AlGaAs quantum wells at room temperature. In a magnetic field of 75 kOe, the resistance of nanostructure being studied increases by a factor of 1.85. The magnetoresistance depends quadratically on the magnetic f

H. T. C. Stoof

We present a general framework in which we can accurately describe the non-equilibrium dynamics of trapped atomic gases. This is achieved by deriving a single Fokker-Planck equation for the gas. In this way we are able to discuss not only the dynamics of an interacting gas above and below the critical temperature at which the gas becomes superfluid, but also

E. G. Maksimov, P. I. Arseyev, N. S. Maslova

The expression for additional subgap current in the presence of electron-phonon interaction is derived. We show that the phonon assisted tunneling leads to appearance of peaks on current-voltage characteristics at the Josephson frequencies corresponding to the Raman-active phonons. The relation of the obtained results to experimental observations are discuss

A. Hucht, K. D. Usadel

The reorientation transition of the magnetization of ferromagnetic films is studied on a microscopic basis within a Heisenberg spin model. Using a modified mean field formulation it is possible to calculate properties of magnetic thin films with non-integer thicknesses. This is especially important for the reorientation transition in Ni/Cu(001), as there the

Nikolai N. Gor&#39;kavyi, Leonid M. Ozernoy, Tatiana Taidakova

In part I, using an effective computational approach, we have reconstructed the population of dust sources between Jupiter and Neptune. Here, in part II, we present the results on distribution of dust produced by 157 real sources (100 Jupiter-family comets with semi-major axes $a<20$ AU, 51 Kuiper belt, and 6 Centaur objects) as well as 211 fictitious source

Leonid M. Ozernoy, Nikolai N. Gor&#39;kavyi, Tatiana Taidakova

We employ an efficient numerical approach to simulate a stationary distribution of test objects, which results from their gravitational scattering on the four giant planets, with accounting for effects of mean motion resonances. Using the observed distribution of the Kuiper belt objects, we reconstruct, in the space of orbital coordinates, the distribution f

A. Valinia, M. J. Henriksen, M. Loewenstein, K. Roettiger

Abell 754, a cluster undergoing merging, was observed in hard X-rays with the Rossi X-ray Timing Explorer (RXTE) in order to constrain its hottest temperature component and search for evidence of nonthermal emission. Simultaneous modeling of RXTE data and those taken with previous missions yields an average intracluster temperature of $\sim 9$ keV in the 1-5

Chorng-Yuan Hwang, K. Y. Lo, Yu Gao, Robert A. Gruendl

We report mid-infrared observations of several luminous infrared galaxies (LIGs) carried out with the Infrared Space Observatory. Our sample was chosen to represent different phases of a merger sequence of galaxy-galaxy interaction with special emphasis on early/intermediate stages of merging. The mid-infrared emission of these LIGs shows extended structures

Mark H. Finger, Lars Bildsten, Deepto Chakrabarty, Thomas A. Prince

We present observations of a series of 10 outbursts of pulsed hard X-ray flux from the transient 10.6 mHz accreting pulsar GS 1843-02, using the Burst and Transient Source Experiment on the Compton Gamma Ray Observatory. These outbursts occurred regularly every 242 days, coincident with the ephemeris of the periodic transient GRO J1849-03 (Zhang et al. 1996)

G. Lagache, A. Abergel, F. Boulanger, J. L. Puget

Using DIRBE and FIRAS maps at high latitude ($|b|>10^{\circ}$) we derive the spatial distribution of the dust temperature associated with the diffuse cirrus and the dense molecular clouds. For a $ν^2$ emissivity law, we find that the equilibrium dust temperature of the cirrus is about 17.5 K with only small variations over the high latitude sky. Comparison o

S. Perlmutter, G. Aldering, S. Deustua, S. Fabbro

This presentation reports on first evidence for a low-mass-density/positive-cosmological-constant universe that will expand forever, based on observations of a set of 40 high-redshift supernovae. The experimental strategy, data sets, and analysis techniques are described. More extensive analyses of these results with some additional methods and data are pres

Marcella Contini, Liliana Formiggini

We investigate the evolution of RR Tel after the outburst by fitting the emission spectra in two epochs. The first one (1978) is characterized by large fluctuations in the light curve and the second one (1993) by the slow fading trend. In the frame of a colliding wind model two shocks are present: the reverse shock propagates in the direction of the white dw

Joseph C. Weingartner, Bruce T. Draine

We discuss the forces on grains exposed to anisotropic radiation fields, including the usual ``radiation pressure&#39;&#39; force and also recoil forces due to photoemitted electrons, photodesorbed hydrogen atoms, and hydrogen molecules which form on the grain surface. We show that these forces can lead to grain dynamics in photodissociation regions which re

Amir H. Abbassi, Sh. Khosravi

Observational evidence from variety of sources points at an accelerating universewhich is approximately spatially flat and with $(Ω_M,Ω_Λ)_0\approx(0.3,0.7)$. We have shown that for low redshifts, $z\leq 0.2$, the metric of this cosmological model is equivalant to the de Sitter metric within one percent error. Among various coordinate descriptions for the fl

John Cardy

The critical behaviour of correlation functions near a boundary is modified from that in the bulk. When the boundary is smooth this is known to be characterised by the surface scaling dimension $\xt$. We consider the case when the boundary is a random fractal, specifically a self-avoiding walk or the frontier of a Brownian walk, in two dimensions, and show t

A. Gorsky

We discuss the behaviour of the spectral density of the massless Dirac operator at the small eigenvalues and quark masses compatible with the restrictions imposed by the low energy theorems in QCD. Sum rule for its derivative over the quark mass is found.

J. Goryo, K. Ishikawa

We show in this letter that P- and T-odd terms of the electromagnetic potentials (P; parity, T; time reversal) are induced and lead an unusual phenomenon in P- and T-violating superconductors discovered recently. The Ginzburg-Landau action includes this term in the gauge invariant manner. The coefficient of the term is nearly topological invariant with a sma

Kenzo Ishikawa, Nobuki Maeda, Tetsuyuki Ochiai

We study the compressible states in the quantum Hall system using a mean field theory on the von Neumann lattice. In the lowest Landau level, a kinetic energy is generated dynamically from Coulomb interaction. The compressibility of the state is calculated as a function of the filling factor $ν$ and the width $d$ of the spacer between the charge carrier laye

A. A. Kozhevnikov

The simple derivation of the string equation of motion adopted in the nonrelativistic case is presented, paying the special attention to the effects of finite masses of bosonic fields of an Abelian Higgs model. The role of the finite mass effects in the evaluation of various topological characteristics of the closed strings is discussed. The rate of the diss

Robert J. Bursill, Ross H. McKenzie, Chris J. Hamer

Using a new version of the density-matrix renormalization group we determine the phase diagram of a model of an antiferromagnetic Heisenberg spin chain where the spins interact with quantum phonons. A quantum phase transition from a gapless spin-fluid state to a gapped dimerized phase occurs at a non-zero value of the spin-phonon coupling. The transition is

O. B. Zaslavskii

Let group generators having finite-dimensional representation be realized as Hermitian linear differential operators without nhomogeneous terms as takes place, for example, for the SO(n) group. Then orresponding group Hamiltonians containing terms linear in generators (along with quadratic ones) give rise to quasi-exactly solvable models with a magnetic fiel

A. V. Tsiganov

By using non-canonical transformation between the Holt system and the Henon-Heiles system the Lax pairs for all the integrable cases of the Holt system are constructed from the known Lax representations for the Henon-Heiles system.

V. V. Flambaum, V. G. Zelevinsky

It is demonstrated that radiative corrections increase tunneling probability of a charged particle.

E. D. Davis, C. R. Gould

Ratios involving on-resonance measurements of the three-fold and five-fold correlation cross sections for which the dependence on some of the unknown spectroscopic data is eliminated are considered. Closed form expressions are derived for the statistical distributions of these ratios. Implications for bounds on the variance of matrix elements of time reversa

A. Pajitnov

One of the basic objects in the Morse theory of circle-valued maps is Novikov complex - an analog of the Morse complex of Morse functions. Novikov complex is defined over the ring of Laurent power series with finite negative part. The main aim of this paper is to present a detailed and self-contained exposition of the author&#39;s theorem saying that C^0-gen

Reinhard Haering-Oldenburg

We define an action of Artin&#39;s braid group on a finite dimensional algebra.