June 1998 arXiv papers — page 5

Steven B. Kraemer, Jose R. Ruiz, D. Michael Crenshaw

The physical conditions in the inner narrow line region (NLR) of the Seyfert 2 galaxy, NGC 1068, are examined using ultraviolet and optical spectra and photoionization models. The spectra are Hubble Space Telescope (HST) Harchive data obtained with the Faint Object Spectrograph (FOS). We selected spectra of four regions, taken through the 0.3" FOS apertu

S. Jordan, P. Schmelcher, W. Becken, W. Schweizer

The nature of the strong absorption features in the white dwarf GD229 has been a real mystery ever since it was found to be magnetic in 1974. All attempts to explain the spectrum by line components of hydrogen failed. With the first sets of newly calculated line data for HeI in a strong magnetic field we could identify most of the absorption structures in th

Hideyuki Umeda, Naoki Iwamoto, Sachiko Tsuruta, Letao Qin

The thermal evolution of a neutron star is studied by including the energy loss due to axion emission. Two axion models and three types of neutron-star matter equation of state are used with the effects of nucleon superfluidity properly taken into account. In comparison with the observational data of PSR0656+14 from ROSAT, the upper limits on the axion mass

Chiaki Kobayashi, Takuji Tsujimoto, Ken'ich Nomoto, Izumi Hachisu

We introduce a metallicity dependence of Type Ia supernova (SN Ia) rate into the Galactic and cosmic chemical evolution models. In our SN Ia progenitor scenario, the accreting white dwarf (WD) blows a strong wind to reach the Chandrasekhar mass limit. If the iron abundance of the progenitors is as low as [Fe/H] < -1, then the wind is too weak for SNe Ia to o

Z. G. Dai, Y. F. Huang, T. Lu

A GRB afterglow has been commonly thought to be due to continuous deceleration of a postburst fireball. Many analytical models have made simplifications for deceleration dynamics of the fireball and its radiation property, although they are successful at explaining the overall features of the observed afterglows. We here propose a model for a GRB afterglow i

Y. F. Huang, Z. G. Dai, D. M. Wei, T. Lu

The postburst evolution of fireballs that produce $γ$-ray bursts is studied, assuming the expansion of fireballs to be adiabatic and relativistic. Numerical results as well as an approximate analytic solution for the evolution are presented. Due to adoption of a new relation among $t$, $R$ and $γ$ (see the text), our results differ markedly from the previous

Alister Graham, Matthew Colless, Giovanni Busarello, Simone Zaggia

We present extended stellar kinematics for a sample of 13 elliptical galaxies in the Fornax cluster. Major-axis velocity dispersion profiles (VDPs) and rotation curves (RCs) are given for 12 of the galaxies. A major feature of this data is the spatial extension: for 8 galaxies the data extends beyond 1 R_e, and for 5 it extends beyond 2 R_e. Compared to the

Richard I. Klein, Robert T. Fisher, Christopher F. McKee, J. Kelly Truelove

We describe a powerful methodology for numerical solution of 3-D self-gravitational hydrodynamics problems with extremely high resolution. Our method utilizes the technique of local adaptive mesh refinement (AMR), employing multiple grids at multiple levels of resolution. These grids are automatically and dynamically added and removed as necessary to maintai

Alberto Noriega-Crespo, Peter M. Garnavich, Sergio Molinari

The physical characteristics of Cepheus E (Cep E) `embedded&#39; outflow are analyzed using ISOCAM images in the v=0-0 S(5) 6.91 um and S(3) 9.66 um molecular hydrogen lines. We find that the morphology of the Cep E outflow in the ground vibrational H2 lines is similar to that of the near infrared v=1-0 2.12 um line. At these mid-IR wavelengths, we do not de

C. S. Reynolds, A. J. Young, M. C. Begelman, A. C. Fabian

The relativistically broad X-ray iron line seen in many AGN spectra is thought to originate from the central regions of the putative black hole accretion disk. Both the line profile and strength will vary in response to rapid variability of the primary X-ray continuum source. The temporal response of the line contains information on the accretion disk struct

Brandon Carter

It is shown that for any elastic string model with energy density $U$ and tension $T$, the divergent contribution from gravitational self interaction can be allowed for by an action renormalisation proportional to $(U-T)^2$. This formula is applied to the important special case of a bare model of the transonic type (characterised by a constant value of the p

Alexei K. Kolezhuk

I study a spin system consisting of strongly coupled dimers which are in turn weakly coupled in a plane by zigzag interactions. The model can be viewed as the strong-coupling limit of a two-dimensional zigzag chain structure typical, e.g., for the $(ac)$-planes of KCuCl_3. It is shown that the magnetization curve in this model has plateaus at 1/3 and 2/3 of

Thomas Appelquist, Anuradha Ratnaweera, John Terning, L. C. R. Wijewardhana

We investigate the chiral phase transition in SU(N) gauge theories as the number of quark flavors, $N_f$, is varied. We argue that the transition takes place at a large enough value of $N_f$ so that it is governed by the infrared fixed point of the $β$ function. We study the nature of the phase transition analytically and numerically, and discuss the spectru

S. Corley, T. Jacobson

High frequency dispersion does not alter the low frequency spectrum of Hawking radiation from a single black hole horizon, whether the dispersion entails subluminal or superluminal group velocities. We show here that in the presence of an inner horizon as well as an outer horizon the superluminal case differs dramatically however. The negative energy partner

P. F. L. Maxted, T. R. Marsh, C. Moran, V. S. Dhillon

We present spectroscopy and photometry of GD 448, a detached white dwarf - M dwarf binary with a period of 2.47h. We find that the NaI 8200A feature is composed of narrow emission lines due to irradiation of the M dwarf by the white dwarf within broad absorption lines that are essentially unaffected by heating. Combined with an improved spectroscopic orbit a

Jérôme Charles

Penguin contributions, being not negligible in general, can hide the information on the CKM angle alpha coming from the measurement of the time-dependent B0(t) -> pi+pi- CP-asymmetry. Nevertheless, we show that this information can be summarized in a set of simple equations, expressing alpha as a multi-valued function of a single theoretically unknown parame

Vladimir B. Braginsky, Michael L. Gorodetsky, Farid Ya. Khalili

Quantum mechanics sets severe limits on the sensitivity and required circulating energy in traditional free-mass gravitational-wave antennas. One possible way to avoid these restrictions is the use of intracavity QND measurements. We analyze a new QND observable, which possesses a number of features that make it a promising candidate for such measurements an

B. Kneer, T. Wong, K. Vogel, W. P. Schleich

We present a generic model of an atom laser by including a pump and loss term in the Gross-Pitaevskii equation. We show that there exists a threshold for the pump above which the mean matter field assumes a non-vanishing value in steady-state. We study the transient regime of this atom laser and find oscillations around the stationary solution even in the pr

Susanne Adler, Thomas Buchert

The Lagrangian theory of structure formation in cosmological fluids, restricted to the matter model ``dust&#39;&#39;, provides successful models of large-scale structure in the Universe in the laminar regime, i.e., where the fluid flow is single-streamed and ``dust&#39;&#39;-shells are smooth. Beyond the epoch of shell-crossing a qualitatively different beha

S. Groote, J. G. Körner, J. A. Leyva

We calculate the linear and circular polarization of gluons produced in conjunction with massive quarks in the annihilation process $e^+e^-\to q \bar q G$. The linear polarization is calculated in the hadron event plane as well as in the gluon-beam plane. Beam polarization and polar orientation effects are included in our discussion. For typical top pair pro

Ian I. Kogan, Gloria Luzon

The Maldacena&#39;s proposal has established an intriguing connection between string theory in AdS spaces and gauge theory. In this paper we study the effects of adding D(-1)-branes to the system of D3- or (D1-D5)-branes and we give arguments indicating that D(-1)-branes are necessary to describe four and two dimensional instantons.

Asok K. Sen, Abhijit Kar Gupta

In a recent paper [Phys. Rev. B{\bf57}, 3375 (1998)], we examined in detail the nonlinear (electrical) dc response of a random resistor cum tunneling bond network ($RRTN$, introduced by us elsewhere to explain nonlinear response of metal-insulator type mixtures). In this work which is a sequel to that paper, we consider the ac response of the $RRTN$-based co

Christof Zalka

We present fast and highly parallelized versions of Shor&#39;s algorithm. With a sizable quantum computer it would then be possible to factor numbers with millions of digits. The main algorithm presented here uses FFT-based fast integer multiplication. The quick reader can just read the introduction and the ``Results&#39;&#39; section.

Bruno Galvan

The problem of defining the boundary conditions for the universe is considered here in the framework of a classical dynamical theory, pointing out that a measure on boundary conditions must be included in the theory in order to explain the statistical regularities of evolution. It is then suggested that quantum statistical regularities also could derive from

M. Murao, D. Jonathan, M. B. Plenio, V. Vedral

A quantum telecloning process combining quantum teleportation and optimal quantum cloning from one input to M outputs is presented. The scheme relies on the establishment of particular multiparticle entangled states, which function as multiuser quantum information channels. The entanglement structure of these states is analyzed and shown to be crucial for th

F. Cannata, G. Junker, J. Trost

Using the Darboux method and its relation with supersymmetric quantum mechanics we construct all SUSY partners of the harmonic oscillator. With the help of the SUSY transformation we introduce ladder operators for these partner Hamiltonians and shown that they close a quadratic algebra. The associated coherent states are constructed and discussed in some det

Arun Kumar Pati, Suresh V. Lawande

If unitary evolution of a quantum system is interrupted by a sequence of measurements we call the dynamics as quantum Zeno dynamics. We show that under quantum Zeno dynamics not only the transition probability (leading to quantum Zeno effect) but also phases are affected. We call this new effect as quantum Zeno phase effect (QZPE) which says that under repea

M. Ardehali

This paper has been withdrawn.

Ileana M. Tibuleac, E. T. Herrin

The regional phase Lg is used to estimate location and magnitude for sources closer than 1500 km. The complexity of Lg waveforms makes it difficult to consistently determine Lg arrival time, thus affecting source location with a single station or array. This study tests an automatic method for timing Lg arrivals using wavelet transforms to decompose the Lg s

Jeremy S. Heyl, Lars Hernquist

We calculate the atomic structure of hydrogen and helium, atoms and molecules in an intense magnetic field, analytically and numerically with a judiciously chosen basis.

Vladimir G. Baryshevsky

The equations describing the VFEL lasing in case of an electron beam moving either in a split of a diffraction grating or in a vacuum waveguide containing a diffraction grating (vacuum VFEL) have been obtained. The dispersion equation allowing to find the vacuum VFEL gain in one-mode generation regime have been considered. It is shown that the vacuum VFEL am

Bijoy Kundu, B. K. Jain, A. B. Santra

A detailed study of the elementary p(p,p$&#39;π^{+}$)n reaction is presented using the delta isobar model. In this model, in the first step one of the two protons in the initial state gets excited to $Δ$. This, in the second step, decays into a nucleon and a pion. For the $pp \to NΔ$ step the parametrized form of the DWBA t-matrix of Jain and Santra, which r

Colin Wilkin

Un choix personnel a ete fait d&#39;evenements memorables du programme de physique realise a Saturne-2 pendant les derniers 20 ans.

Colin Wilkin

A personal choice is made of the highlights of the physics programme carried out at the Saturne-2 facility over the last twenty years.

J. Humblet, A. Csoto, K. Langanke

The R- and K-matrix parametrizations are analyzed and compared for the elastic alpha-alpha scattering at center-of-mass energies below 40 MeV. The two parametrizations differ in their definitions of the resonance energy which can lead to quite different results. The physical values of the best-fit parameters are compared with those computed for a potential m

U. Meyer, A. A. Raduta, Amand Faessler

The coherent state model (CSM) and the triaxial rotation-vibration model (TRVM) are alternatively used to describe the ground, gamma and beta bands of 228Th. CSM is also applied to the nuclei 126Xe and 130Ba, which were recently considered in TRVM. The two models are compared with respect to both their underlying assumptions and to their predicted results fo

Aleksandr V. Pukhlikov

A consistent exposition of the arguments and constructions of the method of maximal singularities, the aim of which is to describe birational iso/automorphisms of Fano varieties and Fano fibrations. The principal elements of the method are considered: N{\&#34; o}ther-Fano inequality, maximal cycles, infinitely near maximal singularities, exclusion and untwis

A. Libgober, S. Yuzvinsky

The paper provides a combinatorial method to decide when the space of local systems with non vanishing first cohomology on the complement to an arrangement of lines in a complex projective plane has as an irreducible component a subgroup of positive dimension. Partial classification of arrangements having such a component of positive dimension and a comparis

Anna-Barbara Berger, Ines Stassen

Pulling back the weight system associated with the exceptional Lie algebra G_2 by a modification of the universal Vassiliev-Kontsevich invariant yields a link invariant; extending it to 3-nets, we derive a recursive algorithm for its evaluation.

C. Duval, L. Guieu

We investigate, in some details, symplectic equivalence between several conformal classes of Lorentz metrics on the hyperboloid of one sheet $H^{1,1} \cong T \times T - Δ$ and affine coadjoint orbits of the group $Diff_+(Δ)$ of orientation preserving diffeomorphisms of $Δ\cong T$ with its natural projective structure. This will allow for generalizations, nam

K. Takemura, D. Uglov

A representation of the Quantum Toroidal Algebra of type sl(N) is constructed on every irreducible integrable highest weight module of the Quantum Affine Algebra of type gl(N). As an intermediate step in the construction, we obtain a quantum analogue of the classical level-rank duality, describing the reciprocal decomposition of the q-Fock space with respect

D. Shklyarov, S. Sinel&#39;shchikov, L. Vaksman

This work considers the algebras of functions in the quantum matrix ball. An explicit formula for a positive invariant integral is presented.

C. A. G. Sasaki, D. G. G. Sasaki, S. P. Sorella

A nonlinear vector supersymmetry for three-dimensional topological massive Yang-Mills is obtained by making use of a nonlinear but local and covariant redefinition of the gauge field.

G. R. Farrar, G. Gabadadze, M. Schwetz

We study the spectrum of the softly broken generalized Veneziano-Yankielowicz effective action for N=1 SUSY Yang-Mills theory. Two dual formulations of the effective action are given. The spurion method is used for the soft SUSY breaking. Masses of the bound states are calculated and mixing patterns are discussed. Mass splittings of pure gluonic states are c

A. Yu. Kamenshchik, I. M. Khalatnikov, M. Martellini

Recently proposed by Hwang, Marnelius and Saltsidis zeta regularization of basic commutators in string theories is generalized to the string models with non-trivial vacuums. It is shown that implementation of this regularization implies the cancellation of dangerous terms in the commutators between Virasoro generators, which break Jacobi identity.

M. R. Pennington

This talk is in two parts both entitled mass production requires precision engineering. The first is about the dynamical generation of mass for matter particles in gauge theories. I will explain how the details of this depend on a precision knowledge of the interactions. The second is about tests of the mechanism of chiral symmetry breaking in QCD that the p

D. B. Fairlie

The Wigner-Weyl- Moyal approach to Quantum Mechanics is recalled, and similarities to classical probability theory emphasised. The Wigner distribution function is generalised and viewed as a construction of a bosonic object, a target space co-ordinate, for example, in terms of a bilinear convolution of two fermionic objects, e.g. a quark antiquark pair. This

V. I. Man&#39;ko, L. Rosa, P. Vitale

The recently proposed probability representation of quantum mechanics is generalized to quantum field theory. We introduce a probability distribution functional for field configurations and find an evolution equation for such a distribution. The connection to the time-dependent generating functional of Green&#39;s functions is elucidated and the classical li

Alan. R. White

This talk outlines the derivation of a high-energy, transverse momentum cut-off, solution of QCD in which the Regge pole and ``single gluon&#39;&#39; properties of the pomeron are directly related to the confinement and chiral symmetry breaking properties of the hadron spectrum. In first approximation, the pomeron is a single reggeized gluon plus a ``wee par

Robert H. Brandenberger

Many particle physics models of matter admit solutions corresponding to stable or long-lived topological defects. In the context of standard cosmology it is then unavoidable that such defects will form during phase transitions in the very early Universe. Certain types of defects lead to disastrous consequences for cosmology, others may play a useful role, as

Andrzej J. Buras

These lectures describe in detail the effective Hamiltonians for weak decays of mesons constructed by means of the operator product expansion and the renormalization group method. We calculate Wilson coeffcients of local operators, discuss mixing of operators under renormalization, the anomalous dimensions of operators and anomalous dimension matrices. We el

L. Lavoura

In a recent paper, Banuls and Bernabeu have claimed the existence of a new form of indirect CP violation which would have its most prominent manifestation in the $B_d$-$\bar B_d$ system. I analyse this claim in detail. I emphasize the fact that it is necessary to take into account the precise experimental method if one is to identify correctly the weak phase

Mark Hindmarsh

I report on recent numerical simulations of the simplest field theory with cosmic string solutions, the Abelian Higgs model. We find that random networks of string quickly converge to a scaling solution in which the network scale length $ξ$ increases linearly with time. There are very few loops with sizes less than $ξ$, and the strings are smooth, showing no

E. Laenen, G. Oderda, G. Sterman

We derive threshold resummations for single-particle and single-jet inclusive cross sections, thus generalizing previous results at fixed invariant mass to a wider class of cross sections with phenomenological interest. We confirm the structure of our resummed expressions by comparison with explicit one-loop calculations for direct photons and heavy quarks.

S. T. Petcov

The solar neutrino problem is reviewed and the possible vacuum oscillation and MSW solutions of the problem are considered.

Jochen Biebel

I present a short overview over W pair production and studies of angular differential cross-sections with and without initial state radiation applying semi-analytical methods and using the Fortran program GENTLE. The influence of anomalous couplings to this process is also discussed.

L. Micu

The main assumption of the model is that in soft processes mesons behave like systems made of valence quarks and an effective vacuum- like field. The 4-momentum of the latter represents the relativistic generalization of the potential energy. The electromagnetic form factors are expressed in terms of the overlap integral of the initial and final wave functio

Einan Gardi, Georges Grunberg, Marek Karliner

Solving the QCD renormalization group equation at the 2-loop and 3-loop orders we obtain explicit expressions for the coupling as a function of the scale in terms of the Lambert W function. We study the nature of the ``Landau singularities'' in the complex Q^2 plane and show that perturbative freezing can lead, in certain cases, to an analyticity structure t

E. Cuautle, G. Herrera

We show that the presence of residual Bose-Einstein correlations may affect the resonant contribution of hadronic charm decays where two identical pions appear in the final state. The distortion of the phase space of the reaction would be visible in the dalitz plot. The decay D+ --> K- pi+ pi+ is discussed but results can be generalized to any decay with ide

U. K. Yang, A. Bodek

We extract the ratio of the down (d) and up (u) parton distribution functions (PDF&#39;s) from the ratio of NMC deuteron and proton structure function F_2(d)/F_2(p), using corrections for nuclear binding effects in the deuteron, which are extracted from the nuclear dependence of SLAC F_2 data. Significant corrections to the d quark distribution in standard P

Tsung-Wen Yeh

We investigate the Lambda_b polarization problem in the inclusive semileptonic decays of a polarized Lambda_b baryon, using the modified perturbative QCD formalism which includes Sudakov suppression. According to HQEFT, we show that, at the leading order in the 1/M_b expansion, the polarized and unpolarized distribution functions become one single universal

Anna Hasenfratz, Chet Nieter

We study the topological content of the SU(3) vacuum using the renormalization group (RG) mapping method. RG mapping is a simple smoothing algorithm, in which a series of APE-smearing steps are done while the topological content of the configuration is carefully monitored. This monitoring process makes it possible to separate true topological objects from va

F. Abe et al, CDF Collaboration

We present a measurement of the time-dependent asymmetry in the rate for $\bar{B}{^0_d}$ versus $B^0_d$ decays to $J/ψK^0_S$. In the context of the Standard Model this is interpreted as a measurement of the CP-violation parameter $\sin(2β)$. A total of $198\pm 17$ $B^0_d/\bar{B}{^0_d}$ decays were observed in $p\bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV by

KARMEN group, B. Armbruster, I. M. Blair, B. A. Bodmann

The KARMEN experiment uses the reaction 12C(ν_e,e-)12N to measure the energy distribution of ν_e emitted in muon decay at rest. The ν_e analog ω_l of the famous Michel parameter ρhas been derived from a maximum-likelihood analysis of events near the kinematic end point, E_max. The result, ω_l = (2.7^{+3.8}_{-3.3}\pm 3.1) * 10^{-2}, is in good agreement with

NuTeV Collaboration, U. K. Yang, C. McNulty, C. G. Arroyo

Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F_2, xF_3(nu), xF_3(nubar) and R(longitudinal) in the kinematic region 0.01<x<0.6 and 1<Q^2<300 GeV^2. The new measurements of R in the x<0.1 region provide a constraint on the level of the gluon distribution. The

Robert M. Wald

I describe a new approach (developed in collaboration with D.E. Holz) to calculating the statistical distributions for magnification, shear, and rotation of images of cosmological sources due to gravitational lensing by mass inhomogeneities on galactic and smaller scales. Our approach is somewhat similar to that used in ``Swiss cheese&#39;&#39; models, but t

Dan N. Vollick

A wormhole is constructed by cutting and joining two spacetimes satisfying the low energy string equations with a dilaton field. In spacetimes described by the &#34;string metric&#34; the dilaton energy-momentum tensor need not satisfy the weak or dominant energy conditions. In the cases considered here the dilaton field violates these energy conditions and

M. Mars, J. M. M. Senovilla

The problem of constructing global models describing isolated axially symmetric rotating bodies in equilibrium is analyzed. It is claimed that, whenever the global spacetime is constructed by giving boundary data on the limiting surface of the body and integrating Einstein&#39;s equations both inside and ouside the body, the problem becomes overdetermined. S

Atsushi Higuchi, George E. A. Matsas, Daniel Sudarsky

We show that the response rate of (i) a static source interacting with Hawking radiation of massless scalar field in Schwarzschild spacetime (with the Unruh vacuum) and that of (ii) a uniformly accelerated source with the same proper acceleration in Minkowski spacetime (with the Minkowski vacuum) are equal. We show that this equality will not hold if the Unr

Yasunori Fujii

We discuss the implications of the proposed gravitational redshift experiment on antihydrogens. We show that the result should be the same as on hydrogens in spite of different free-fall accelerations (WEP violation) which may occur if there is a vector fifth-force field. We emphasize the experiment is unique in the sense that it tests the Equivalence Princi

C. W. Gardiner, M. D. Lee, R. J. Ballagh, M. J. Davis

In a major extension of our previous model (C.W. Gardiner, P. Zoller, R.J. Ballagh and M.J. Davis, Phys. Rev. Lett. 79, 1793 (1997)) of condensate growth, we take account of the evolution of the occupations of lower trap levels, and of the full Bose-Einstein formula for the occupations of higher trap levels. We find good agreement with experiment, especially

Seung-Yeon Kim, Richard J. Creswick

The microcanonical transfer matrix is used to study the distribution of the Fisher zeros of the $Q>2$ Potts models in the complex temperature plane with nonzero external magnetic field $H_q$. Unlike the Ising model for $H_q\ne0$ which has only a non-physical critical point (the Fisher edge singularity), the $Q>2$ Potts models have physical critical points fo

M. Thomas, H. R. Blank, K. C. Wong, H. Kroemer

We have studied the current-voltage characteristics of superconducting weak links in which the coupling medium is the 2-D electron gas in InAs-based semiconductor quantum wells, with relatively large (typically 0.5 micron) separations between niobium electrodes. The devices exhibit Josephson-like current-voltage characteristics; however, the falloff of the d

T. J. Newman

We present and solve a continuum theory of vacancy-mediated diffusion (as evidenced, for example, in the vacancy driven motion of tracers in crystals). Results are obtained for all spatial dimensions, and reveal the strongly non-gaussian nature of the tracer fluctuations. In integer dimensions, our results are in complete agreement with those from previous e

Harald Kallabis

A crystal surface which is miscut with respect to a high symmetry plane exhibits steps with a characteristic distance. It is argued that the continuum description of growth on such a surface, when desorption can be neglected, is given by the anisotropic version of the conserved KPZ equation (T. Sun, H. Guo, and M. Grant, Phys. Rev. A 40, 6763 (1989)) with no

David Sherrington

An introduction and overview is given of the theory of spin glasses and its application.

Igor Zutic, Oriol T. Valls

We consider an unconventional superconductor in a low frequency harmonic magnetic field. In the Meissner regime at low T a nonlinear magnetic response arises from quasiparticle excitations near minima in the energy gap. Various physical quantities then acquire higher harmonics of the frequency of the applied field. We discuss how examination of the field and

G. G. Kozlov

A method is proposed for calculating the absorption spectrum of a long one-dimensional closed-into-a-ring chain with Frenkel&#39;s exciton under diagonal disorder. This disorder is represented by the hyperbolic singularities of atomic fission. These defects are shown to lead to a wing in the exciton zone of a chain without defects. The form of the wing does

M. Acquarone, J. R. Iglesias, M. A. Gusmao, C. Noce

We consider a model Hamiltonian for a dimer including all the electronic one- and two-body terms consistent with a single orbital per site, a free Einstein phonon term, and an electron-phonon coupling of the Holstein type. The bare electronic interaction parameters were evaluated in terms of Wannier functions built from Gaussian atomic orbitals. An effective

U. Eckern, K. Ziegler

A two-dimensional gas of non-interacting quasiparticles in a nearly periodic potential and a perpendicular magnetic field is studied. The potential is a superposition of a periodic potential, induced e.g. by a charge density wave or a vortex lattice of a type--II superconductor, and a weak random potential due to impurities. Approximating this model by Dirac

K. E. Nagaev

The frequency-dependent shot noise in long and narrow mesoscopic diffusive contacts is numerically calculated. The case of arbitrarily strong electron-electron scattering and zero temperature of electrodes is considered. For all voltages, the noise increases with frequency and tends to finite values. These limiting values are larger than the Poissonian noise

Tetsuya Mutou, Naokazu Shibata, Kazuo Ueda

Combination of the finite-temperature density-matrix renormalization-group and the maximum entropy presents a new method to calculate dynamic quantities of one-dimensional many-body systems. In the present paper, density of states, local dynamic spin and charge correlation functions of the one-dimensional Kondo insulator are discussed. Excitation gaps open w

Yukitoshi Motome, Masatoshi Imada

Ground state properties of multi-orbital Hubbard models are investigated by the auxiliary field quantum Monte Carlo method. A Monte Carlo technique generalized to the multi-orbital systems is introduced and examined in detail. The algorithm contains non-trivial cases where the negative sign problem does not exist. We investigate one-dimensional systems with

D. V. Khveshchenko

We elaborate on a single-mode description of the ballistic charge transport through a narrow constriction in a compressible (composite fermion) Quantum Hall liquid. In the presence of long-range Coulomb interactions we find logarithmic deviations from the Luttinger liquid behavior. These extra logarithmic factors are shown to modify the conductance, shot noi

Bonnie Lynn Webber, Aravind K. Joshi

We here explore a ``fully&#39;&#39; lexicalized Tree-Adjoining Grammar for discourse that takes the basic elements of a (monologic) discourse to be not simply clauses, but larger structures that are anchored on variously realized discourse cues. This link with intra-sentential grammar suggests an account for different patterns of discourse cues, while the di

A. Celani, D. Biskamp

The correlation between inertial range velocity fluctuations and energy dissipation in fully developed turbulence is studied using high resolution direct numerical simulation. Runs with microscale Reynolds number up to ${\cal R}_λ \simeq 300$ have been performed in order to achieve the maximum extent of the scaling range compatible with a proper resolution o

N. Abarenkova, J. -Ch. Anglès d&#39;Auriac, S. Boukraa, S. Hassani

To test a possible relation between the topological entropy and the Arnold complexity, and to provide a non trivial example of a rational dynamical zeta function, we introduce a two-parameter family of two-dimensional discrete rational mappings. The generating functions of the number of fixed points, and of the degree of the successive iterates, are both con

Ali Gokirmak, Dong-Ho Wu, J. S. A. Bridgewater, Steven M. Anlage

We have developed a method to measure the electric field standing wave distributions in a microwave resonator using a scanned perturbation technique. Fast and reliable solutions to the Helmholtz equation (and to the Schrodinger equation for two dimensional systems) with arbitrarily-shaped boundaries are obtained. We use a pin perturbation to image primarily

V. M. Kaspi, F. Crawford, R. N. Manchester, A. G. Lyne

We report the detection of the radio pulsar counterpart to the 69 ms X-ray pulsar discovered near the supernova remnant RCW 103 (G332.4-0.4). Our detection confirms that the pulsations arise from a rotation-powered neutron star, which we name PSR J1617-5055. The observed barycentric period derivative confirms that the pulsar has a characteristic age of only

M. A. Pahre, R. R. de Carvalho, S. G. Djorgovski

The physical origins of the Fundamental Plane (FP) scaling relations are investigated for early-type galaxies observed at optical and near-infrared wavelengths. The slope for the FP is shown to increase systematically with wavelength from the U-band through the K-band. A distance-independent construction of the observables is described which provides an accu

Fulvio Melia, Farhad Yusef-Zadeh, Marco Fatuzzo

Continuum low-frequency radio observations of the Galactic Center reveal the presence of two prominent radio sources, Sgr A East and its surrounding Halo, containing non-thermal particle distributions with power-law indices around 2.5-3.3 and 2.4, respectively. The central 1-2 pc region is also a source of intense (stellar) UV and (dust-reprocessed) far-IR r

J. Greiner, E. Morgan, R. Remillard

The galactic superluminal motion source GRS 1915+105 has been extensively observed with the RXTE satellite over the last two years. More than 250 RXTE pointings have been performed until mid-May 1998 with more than 1.5 Msec exposure time on roughly a weekly basis. Here we report on first results of our spectral analysis of a major part of these pointed RXTE

Federica Musazzi, Ennio Poretti, Stefano Covino, Armando Arellano Ferro

The possibility to perform the frequency analysis of the light variation of V798 Cyg on the basis of a more accurate set of data and the Fourier decomposition of the new light curve of V831 Tau allowed us to improve the knowledge of the HADS. The following points are now better defined: 1) V798 Cyg is confirmed to be a double-mode pulsator and its similarity

Francesco Sylos Labini

There is a general agreement that galaxy structures exhibit fractal properties, at least up to some small scale. However the presence of an eventual crossover towards homogenization, as well as the exact value of the fractal dimension, are still a matter of debate. I summarize the main points of the this discussion, considering also some galaxy surveys which

A. J. Barger, L. L. Cowie, D. B. Sanders, E. Fulton

The global star formation rate in high redshift galaxies, based on optical surveys, shows a strong peak at a redshift of z=1.5, which implies that we have already seen most of the formation. High redshift galaxies may, however, emit most of their energy at submillimeter wavelengths if they contain substantial amounts of dust. The dust would absorb the starli

A. Giveon, D. Kutasov, N. Seiberg

We study string propagation on $AdS_3$ times a compact space from an ``old fashioned&#39;&#39; worldsheet point of view of perturbative string theory. We derive the spacetime CFT and its Virasoro and current algebras, thus establishing the conjectured $AdS$/CFT correspondence for this case in the full string theory. Our results have implications for the extr

Herbert Neuberger

A practical implementation of the Overlap-Dirac operator ${{1+γ_5ε(H)}\over 2}$ is presented. The implementation exploits the sparseness of $H$ and does not require full storage. A simple application to parity invariant three dimensional SU(2) gauge theory is carried out to establish that zero modes related to topology are exactly reproduced on the lattice.

Martina M. Brisudova

We review the light-front Hamiltonian approach for the Abelian gauge theory in 3+1 dimensions, and then study electromagnetic duality in this framework.

Ken D. Olum

The content of gr-qc/9805003 and gr-qc/9806091 now appears in a single paper in the archive under gr-qc/9805003, since these appeared as a single publication in Physical Review Letters.

F. Schmid

Recent developments in off-lattice self-consistent field theories for inhomogeneous complex fluids are reviewed. Particular emphasis is given to the treatment of intermolecular interactions and compressibility, to the role of fluctuations, and to the discussion of the coarse-graining length which is inherent to the theory. Valuable insight can be gained from