November 1999 arXiv papers — page 10

Detlev Buchholz, Martin Florig, Stephen J. Summers

An algebraic characterization of vacuum states in Minkowski space is given which relies on recently proposed conditions of geometric modular action and modular stability for algebras of observables associated with wedge-shaped regions. In contrast to previous work, continuity properties of these algebras are not assumed but derived from their inclusion struc

Robion Kirby, Paul Melvin

The E_8-manifold has several natural framed link descriptions, and we give an efficient method (via `grapes') for showing that they are indeed the same 4-manifold. This leads to explicit handle pictures for the perturbation of singular fibers in an elliptic surface to a collection of fishtails. In the same vein, we show how the degeneration of a regular

Vyacheslav Rychkov

Let T be an oscillatory integral operator on L^2(R) with a smooth real phase function S(x,y). We prove that, in all cases but the one described below, after localization to a small neighborhood of the origin the norm of T decays like N^{-d/2} as the frequency N->infty, where d is the Newton decay rate introduced by Phong and Stein, which is determined by the

G. Corach, D. Stojanoff

Given a definite nonnegative matrix $A \in M_n (C)$, we study the minimal index of A: $I(A) = \max \{λ\ge 0 : A\circ B \ge λB$ for all $0\le B\}$, where $A\circ B$ denotes the Hadamard product $(A\circ B)_{ij} = A_{ij} B_{ij}$. For any unitary invariant norm N in $M_n(C)$, we consider the N-index of A: $I(N,A) = \min\{N(A\circ B) : B\ge 0$ and $N(B) = 1 \}$.

M. Argerami, D. Stojanoff

Let N \subseteq M be von Neumann algebras and E:M\to N a faithful normal conditional expectation. In this work it is shown that the similarity orbit S(E) of E by the natural action of the invertible group of G_M of M has a natural complex analytic structure and the map given by this action: G_M\to S(E) is a smooth principal bundle. It is also shown that if N

David Deutsch, Artur Ekert, Rossella Lupacchini

Though the truths of logic and pure mathematics are objective and independent of any contingent facts or laws of nature, our knowledge of these truths depends entirely on our knowledge of the laws of physics. Recent progress in the quantum theory of computation has provided practical instances of this, and forces us to abandon the classical view that computa

K. -H. Rehren

A theorem is derived which (i) provides a new class of subfactors which may be interpreted as generalized asymptotic subfactors, and which (ii) ensures the existence of two-dimensional local quantum field theories associated with certain modular invariant matrices.

Denis V. Juriev

The interactive game theoretical approach to tactics and behavioral self-organization is developed. Though it uses the interactive game theoretical formalization of dialogues as psycholinguistic phenomena, the crucial role is played by the essentially new concept of a tactical game. Applications to the perception processes and related subjects (memory, recol

Paul Norbury

We show that many hyperbolic monopoles can be distinguished from each other via their asymptotic values in contrast to the case of Euclidean monopoles.

Atsuo Kuniba, Tomoki Nakanishi

The U_q(\hat{sl}(2)) Bethe equation is studied at q=0. A linear congruence equation is proposed related to the string solutions. The number of its off-diagonal solutions is expressed in terms of an explicit combinatorial formula and coincides with the weight multiplicities of the quantum space.

Efstratia Kalfagianni, Xiao-Song Lin

We show that the Vassiliev invariants of orders $\leq n$ of a knot K, are obstructions to finding a regular Seifert surface, S, whose complement looks "simple" (e.g. like the complement of a disc) to the lower central series of its fundamental group. As a consequence of this, we obtain that the Vassiliev invariants of the knot $K=\partial S$ are null

G. N. J. Añaños, N. F. Svaiter

We discuss three-dimensional $ λϕ^4+ηϕ^6 $ theory in the context of the 1/N expansion at finite temperature. We use the method of the composite operator (CJT) for summing a large sets of Feynman graphs. We analyse the behavior of the thermal square mass and the thermal coupling constant in the low and high temperature limit. The existent of the tricritical p

David C. Dunbar, Bernard Julia, Domenico Seminara, Mario Trigiante

We compute the one-loop divergences of D=10, N=1 supergravity and of its reduction to D=8. We study the tensor structure of the counterterms appearing in D=8 and D=10 and compare these to expressions previously found in the low energy expansion of string theory. The infinities have the primitive Yang-Mills tree amplitude as a common factor.

Bin Wang, Elcio Abdalla

The Fischler-Susskind entropy bound has been studied in (2+1)-dimensional universes with negative cosmological constant. As in all contracting universes, that bound is not satisfied. Furthermore, we found that the Fischler-Susskind bound is not compatible with a generalized second law of thermodynamics in (2+1)-dimensional cosmology, neither the classical no

Shin'ichi Nojiri, Sergei D. Odintsov

We generalize the local surface counterterm prescription suggested in Einstein gravity for higher derivative (HD) and Weyl gravities. Explicitly, the surface counterterm is found for three- and five-dimensional HD gravities. As a result, the gravitational action for asymptotically AdS spaces is finite and gravitational energy-momentum tensor is well-defined.

G. C. Branco, D. Emmanuel-Costa, R. Gonzalez Felipe

We investigate the physical meaning of some of the "texture zeros" which appear in most of the Ansatze on quark masses and mixings. It is shown that starting from arbitrary quark mass matrices and making a suitable weak basis transformation one can obtain some of these sets of zeros which therefore have no physical content. We then analyse the physic

O. V. Suvorova

I summarize here and discuss the results of presently operating neutrino telescopes in searching for a signal of dark matter weakly interacting massive particles (WIMPs).

M. Gorchtein, D. Drechsel, B. Pasquini, M. Vanderhaeghen

Fixed-$t$ subtracted dispersion relations are presented for Compton scattering off the nucleon at energies $E_γ\leq 500$ MeV, as a formalism to extract the nucleon polarizabilities from the data with a minimum of model dependence. The scalar polarizabilities difference $α- β$ and the backward spin polarizability $γ_π$ enter directly as fit parameters in this

N. E. Ligterink

We determine the numerical values of scalar multi-loop two-vertex Feynman diagrams, the generalized sunset diagrams, by integrating all but the longitudinal momenta analytically. For the longitudinal momenta we introduce one collective coordinate, which allows us to determine the numerical value of the diagram efficiently and to an arbitrary accuracy. The im

Andrzej Czarnecki, Savely G. Karshenboim

We briefly review the theoretical and experimental results concerning decays of positronium. Possible solutions of the "orthopositronium lifetime puzzle" are discussed. Positronium annihilation into neutrinos is examined and disagreement is found with previously published results.

N. Hammon, H. Stöcker, W. Greiner, A. Dumitru

We calculate the yields of pions, kaons, and $ϕ$-mesons for RHIC and LHC energies assuming thermodynamical equilibration of the produced minijets, and using as input results from pQCD for the energy densities at midrapidity. In the calculation of the production of partons and of transverse energy one has to account for nuclear shadowing. By using two paramet

Reinhard Stock

I review the new data presented at QM99. The main emphasis is placed on the CERN SPS hadron production systematics concluding that the boundary between a partonic and a hadronic phase has now been located at $T=180 \pm10\:MeV$ and $ε\approx 1 \:GeV$ per $fm^3$.

M. Jezabek, P. Urban

We give an analytic formula for the double distribution of hadronic invariant mass and charged lepton energy to one-loop order of the perturbative QCD. Although infrared singular, this quantity is closely related to physical observables that can be obtained thereof through proper convolution.

Matteo Beccaria, Carlo Presilla, Gian Fabrizio De Angelis, Giovanni Jona-Lasinio

We present a simple derivation of a Feynman-Kac type formula to study fermionic systems. In this approach the real time or the imaginary time dynamics is expressed in terms of the evolution of a collection of Poisson processes. A computer implementation of this formula leads to a family of algorithms parametrized by the values of the jump rates of the Poisso

B. Winstein

In this lecture, I will review results on the study of direct CP violation- where the violation occurs in a particle decay rather than in particle-anti particle mixing. Brief comments on rare decays, particularly those with a CP reach, will be made. Finally, I will indicate how the community would like to see the field evolve.

Caroline Santos

We study the gravi-dilaton field of a Schwarzschild black hole pierced by a thin cosmic string in both massless and massive dilatonic gravity. We conclude that in the thin vortex approximation the string's spacetime is asymptotically flat with a conical deficit angle and that the inertial mass of the black hole is different from the gravitational one. We

S. Deser

We first present a review, intended for classical relativists, of the ultraviolet difficulties faced by local quantum gravity theories in both the usual Einstein versions and in their supergravity extensions, at least perturbatively. These problems, present in arbitrary dimensions, are traceable to the dimensionality of the Einstein constant. We then summari

Marie-Noëlle Célérier

The hot Big-Bang standard model for the evolution of the universe, despite strong successes, lets unresolved a number of problems. One of its main drawbacks, known as the horizon problem, was until now thought to be only solvable by an inflationary scenario. Here is proposed a class of inhomogeneous models of universe, getting rid of some of the worst drawba

Julian Barbour, Niall O Murchadha

The four-dimensional gauge group of general relativity corresponds to arbitrary coordinate transformations on a four-manifold. Theories of gravity with a dynamical structure remarkably like Einstein's theory can be obtained on the basis of a four-dimensional gauge group of arbitrary coordinate and conformal transformations of riemannian metrics defined o

Kengo Maeda, Takashi Torii, Makoto Narita

The cosmic no hair conjecture is tested in the spherically symmetric Einstein-Maxwell-dilaton~(EMD) system with a positive cosmological constant $Λ$. Firstly, we analytically show that once gravitational collapse occurs in the massless dilaton case, the system of field equations breaks down inevitably in outer communicating regions or at the boundary provide

Eloy Ayón-Beato, Alberto García, Alfredo Macías, Hernando Quevedo

Using the equivalence theorem for the triplet ansatz sector of metric-affine gravity (MAG) theories and the Einstein-Proca system, it is shown that the only static black hole of the triplet sector of MAG is the Schwarzschild solution, under the constraint (-4β_4 + k_1β_5/2k_0 + k_2γ_4/k_0)/κz_4 \neq 0 on the coupling constants. For the special case (-4β_4 +

Markus Walther

Recent developments in theoretical linguistics have lead to a widespread acceptance of constraint-based analyses of prosodic morphology phenomena such as truncation, infixation, floating morphemes and reduplication. Of these, reduplication is particularly challenging for state-of-the-art computational morphology, since it involves copying of some part of a p

Alexander N. Korotkov, Konstantin K. Likharev

We have carried out a preliminary analysis of shot noise at hopping, focusing on uniform 1D arrays of sites separated by N tunnel barriers. The results show that at low temperatures the low-frequency density of the shot noise varies from 1/N to 1 of the Schottky value, depending on the geometry, electron density, and Coulomb interaction strength. An interest

V. Latora, A. Rapisarda, S. Ruffo

We discuss recent results obtained for the Hamiltonian Mean Field model. The model describes a system of N fully-coupled particles in one dimension and shows a second-order phase transition from a clustered phase to a homogeneous one when the energy is increased. Strong chaos is found in correspondence to the critical point on top of a weak chaotic regime wh

A. D. Zaikin, D. S. Golubev

We present a nonperturbative approach which allows to evaluate the weak localization correction to the conductivity of disordered conductors in the presence of interactions. The effect of the electron-electron interaction on the magnetoconductance is described by the function A(t)\exp (-f(t)). The dephasing time is determined only by f(t), and this time rema

B. Arnaud, M. Alouani

We used our previously implemented GW approximation (GWA) based on the all-electron full-potential projector augmented wave (PAW) method to study the optical properties of small, medium and large-band-gap semiconductors: Si, GaAs, AlAs, InP, Mg$_2$Si, C, and LiCl. The aim being to study the size of both local-field (LF) and the quasi-particle (QP) correction

A. D. Zaikin, D. S. Golubev, A. van Otterlo, G. T. Zimanyi

We investigate quantum fluctuations in thin superconducting wires. We demonstrate that quantum phase slips dominate the system behavior at low temperatures and are well in the measurable range for sufficiently thin wires. We discuss the effect of dissipation, predict a new quantum superconductor-to-metal (insulator) phase transitions for wires with thickness

A. Schadschneider, D. Chowdhury, E. Brockfeld, K. Klauck

We present a new cellular automata model of vehicular traffic in cities by combining ideas borrowed from the Biham-Middleton-Levine (BML) model of city traffic and the Nagel-Schreckenberg (NaSch) model of highway traffic. The model exhibits a dynamical phase transition to a completely jammed phase at a critical density which depends on the time periods of th

L. Neubert, L. Santen, A. Schadschneider, M. Schreckenberg

Single-vehicle data of freeway traffic as well as selected Floating-Car (FC) data are analyzed in great detail. Traffic states are distinguished by means of aggregated data. We propose a method for a quantitative classification of these states. The data of individual vehicles allows for insights into the interaction of vehicles. The time-headway distribution

K. Bongs, S. Burger, G. Birkl, K. Sengstock

We investigate the evolution of Bose-Einstein condensates falling under gravity and bouncing off a mirror formed by a far-detuned sheet of light. After reflection, the atomic density profile develops splitting and interference structures which depend on the drop height, on the strength of the light sheet, as well as on the initial mean field energy and size

Alain Barrat, Vittorio Loreto

We investigate the response properties of granular media in the framework of the so-called {\em Random Tetris Model}. We monitor, for different driving procedures, several quantities: the evolution of the density and of the density profiles, the ageing properties through the two-times correlation functions and the two-times mean-square distance between the p

G. I. Harus, A. N. Ignatenkov, A. I. Ponomarev, L. D. Sabirzyanova

The 2D weak localization effects at low temperatures T = (0.2-4.2)K have been investigated in nonsuperconducting sample Nd{1.88}Ce{0.12}CuO{4-d} and in the normal state of the superconducting sample Nd{1.82}Ce{0.18}CuO{4-d} for B>B_c2. The phase coherence time and the effective thickness $d$ of a conducting CuO_2 layer have been estimated by the fitting of 2

A. P. Protogenov, V. A. Verbus

We consider the generalized exclusion statistics in the Kondo problem. The thermodynamic Bethe ansatz equations have been used for a multicomponent system of particles obeying the generalized exclusion principle. We have found a relation between the derivative of the phase shift of the scattering matrix for Fermi particles and for particles characterized by

N. M. R. Peres, R. G. Dias, P. D. Sacramento, J. M. P. Carmelo

We study the current, the curvature of levels, and the finite temperature charge stiffness, D(T,L), in the strongly correlated limit, U>>t, for Hubbard rings of L sites, with U the on-site Coulomb repulsion and t the hopping integral. Our study is done for finite-size systems and any band filling. Up to order t we derive our results following two independent

Tobias Hertel, Gunnar Moos

We have studied the dynamics of electrons in single wall carbon nanotubes using femtosecond time-resolved photoemission. The lifetime of electrons excited to the pi* bands is found to decrease continuously from 130 fs at 0.2 eV down to less than 20 fs at energies above 1.5 eV with respect to the Fermi level. This should lead to a significant lifetime--induce

H. P. Büchler, V. B. Geshkenbein, G. Blatter

We present an analytical derivation for the quantum decay rate of the superflow through a weak link in a one-dimensional Bose-Einstein-condensate. The effective action for the phase difference across the link reduces to that of a massive particle with damping subject to a periodic potential. We find an algebraic flow-pressure relation, characteristic for qua

D. Bartolo, D. Long, J. -B. Fournier

The elastic interactions between objects embedded in a nematic liquid crystal are usually caused by the average distorsion-rather than by the fluctuations-of the nematic orientational field. We argue that for sufficiently small particles, the nematic-mediated interaction originates purely from the fluctuations of the nematic director. This Casimir interactio

Liqun He, Eugene Kogan, Moshe Kaveh, Shlomo Havlin

We study by computer simulation distribution functions (DF) of mesoscopic hopping conductance. The DFs obtained for one-dimensional systems were found to be quite close to the predictions of the theory by Raikh and Ruzin. For D=2, the DFs both for narrow system and thin film look similar (and close to the 1D case).The distribution function for the conductanc

F. M. Izrailev

In this review the problem of statistical description of isolated quantum systems of interacting particles is discussed. Main attention is paid to a recently developed approach which is based on chaotic properties of compound states in the basis of non-interacting particles. In order to demonstrate the most important aspects of this approach, the matrix mode

Ricardo L. Viana, Celso Grebogi

An aspect of the synchronization dynamics is investigated in this work. We argue analytically and confirm numerically that the chaotic dynamics on the synchronization manifold exhibits unstable dimension variability. Unstable dimension variability is a cause of severe modeling difficulty for physical phenomena, since trajectories obtained from the mathematic

D. D. Sasselov, M. Lecar

The snow line, in Hayashi's (1981) model, is where the temperature of a black body that absorbed direct sunlight and re-radiated as much as it absorbed, would be 170~K. It is usually assumed that the cores of the giant planets, e.g., Jupiter, form beyond the snow line. Since Hayashi, there have been a series of more detailed models of the absorption by d

Julian Borrill

Realizing the extraordinary scientific potential of the CMB requires precise measurements of its tiny anisotropies over a significant fraction of the sky at very high resolution. The analysis of the resulting datasets is a serious computational challenge. Existing algorithms require terabytes of memory and hundreds of years of CPU time. We must therefore bot

Hironori Matsumoto, Takeshi Go Tsuru, Yasushi Fukazawa, Makoto Hattori

We have analyzed the ASCA data of 29 nearby clusters of galaxies systematically, and obtained temperatures, iron abundances, and X-ray luminosities of their intracluster medium (ICM). We also estimate ICM mass using the beta model, and then evaluate iron mass contained in the ICM and derive the total gravitating mass. This gives the largest and most homogene

Michael Hilker

A new calibration of the Stroemgren (b-y),m_1 diagram in terms of iron abundance of red giants is presented. This calibration is based on a homogeneous sample of giants in the globular clusters omega Centauri, M22, and M55 as well as field giants from the list of Anthony-Twarog & Twarog (1998). Towards high metallicities, the new calibration is connected to

Paulo C. Freire, Fernando Camilo, Duncan R. Lorimer, Andrew G. Lyne

Recent observations of the globular cluster 47 Tuc, made with the Parkes telescope at a wavelength of 20 cm, have resulted in the discovery of nine new millisecond pulsars, all in binary systems. The number of timing solutions available has risen from two to 14. These results will make possible a more detailed study of the cluster dynamics.

Mark L. Houdashelt, Roger A. Bell, Allen V. Sweigart, Robert F. Wing

As part of a project to model the integrated spectra and colors of elliptical galaxies through evolutionary synthesis, we have refined our synthetic spectrum calculations of M giants. After critically assessing three effective temperature scales for M giants, we adopted the relation of Dyck et al. (1996) for our models. Using empirical spectra of field M gia

Giovanni Carraro

I review different methods devised to derive the age of the Galactic Disk, namely the Radio-active Decay (RD), the Cool White Dwarf Luminosity Function (CWDLF), old opne clusters (OOC) and the Color Magnitude Diagram (CMD) of the stars in the solar vicinity. I argue that the disk is likely to be 8-10 Gyr old. Since the bulk of globulars has an age around 13

D. E. Harris, P. E. J. Nulsen, T. P. Ponman, M. Bautz

An observation of the radio galaxy 3C295 during the calibration phase of the Chandra X-ray Observatory reveals X-ray emission from the core of the galaxy, from each of the two prominent radio hotspots, and from the previously known cluster gas. We discuss the possible emission processes for the hotspots and argue that a synchrotron self-Compton model is pref

I. Georgantopoulos

I present ASCA observations of IRAS00317-2142, the most luminous (Lx~10^43 erg s-1 0.1-2 keV) of the 'composite' class of galaxies. This enigmatic class of objects presents narrow-emission line optical spectra classifying these galaxies as star-forming on the basis of the diagnostic emission line ratios; yet, the presence of weak Halpha broad wings a

Thierry Montmerle, Nicolas Grosso, Yohko Tsuboi, Katsuji Koyama

The ASCA satellite has recently detected variable hard X-ray emission from two Class I protostars in the rho Oph cloud, YLW15 (IRS43) and WL6, with a characteristic time scale ~20h. In YLW15, the X-ray emission is in the form of quasi-periodic energetic flares, which we explain in terms of strong magnetic shearing and reconnection between the central star an

Simon D. M. White, Volker Springel

We use high-resolution simulations to show that the current standard paradigm for the growth of structure in the Universe predicts the formation of a galaxy like our own to differ substantially from the classic ELS and Searle/Zinn pictures. On scales larger than the Local Group, the earliest star formation was extremely inhomogeneous, suggesting that the hig

Peter Schilke, David M. Mehringer, Karl M. Menten

We report the detection of a strong submillimeter wavelength HCN laser line at a frequency near 805 GHz toward the carbon star IRC+10216. This line, the J=9-8 rotational transition within the (04(0)0) vibrationally excited state, is one of a series of HCN laser lines that were first detected in the laboratory in the early days of laser spectroscopy. Since it

J. F. Bell

The Square Kilometre Array (SKA) is a proposed next generation radio telescope. Between now and 2005 this project is in a technology development and prototyping phase, with construction likely to begin in $\sim 2010$. This paper describes what the SKA may be like, its key features, the motivation for building it and where you can access more details about it

Cheongho Han, Seong-Hong Park, Jang-Hae Jeong

In this paper, we investigate the color changes of gravitational microlensing events caused by the two different mechanisms of differential amplification for a limb-darkened extended source and blending. From this investigation, we find that the color changes of limb-darkened extended source events (color curves) have dramatically different characteristics d

Frank C. van den Bosch, Brant E. Robertson, Julianne J. Dalcanton, W. J. G de Blok

We re-examine the disk-halo decompositions of the rotation curves of low surface brightness (LSB) galaxies with V_max > 80 km/s, taking full account of the effects of beam smearing. We show that the rotation curves of these LSB galaxies are, contrary to previous claims, consistent with dark halos with steep central cusps in their density distribution. In fac

J. A. Panei, L. G. Althaus, O. G. Benvenuto

Recent measurements made by Hipparcos (Provencal et al. 1998) present observational evidence supporting the existence of some white dwarf (WD) stars with iron - rich, core composition. In this connection, the present paper is aimed at exploring the structure and evolution of iron - core WDs by means of a detailed and updated evolutionary code. In particular,

Andrew Bunker

In this article I review recent developments in near-infrared emission line searches for star-forming galaxies at high redshift. Using the J-, H- & K-bands we can potentially chart the history of star formation over the range 1<z<5 using the prominent rest-optical nebular emission lines alone, filling in the &#34;redshift desert&#34; at z~1-3 where most comm

Tod E. Strohmayer

Observations of thermonuclear (Type I) X-ray bursts from neutron stars in low mass X-ray binaries (LMXB) with the Rossi X-ray Timing Explorer (RXTE) have revealed large amplitude, high coherence X-ray brightness oscillations with frequencies in the 300 - 600 Hz range. Substantial spectral and timing evidence point to rotational modulation of the X-ray burst

S. Mereghetti

The observational properties of the six known Anomalous X-ray Pulsars are described in the context of the main theoretical models for this enigmatic class of objects.

R. T. Edwards

We have conducted a pulsar survey of intermediate Galactic latitudes (15deg < |b| < 5deg) at 20 cm. The survey has been highly successful, discovering 58 new pulsars, eight of which are recycled, in only ~14 days of integration time. One pulsar has a very narrow (2deg FWHM) average profile for the pulsar&#39;s period (278 ms). The six new recycled binary sys

K. S. Cheng, J. H. Fan, Z. G. Dai

Both observations and theoretical models suggest that the emissions in gamma-ray bursts (GRBs) and the afterglows are beamed. We argue that the recent polarization measured in the afterglows gives further evidence of beaming in GRBs. In this approach, we adopted the polarization-magnitude relation of BL Lacertae objects to 4 GRBs with available polarization

A. Ponzi, Y. Aizawa

We describe a financial market model which shows a non-equilibrium phase transition. Near the transition punctuated equilibrium behaviour is seen, with avalanches occuring on all scales. This scaling is described by an exponent very near 1. This system shows intermittent time development with bursts of global synchronization reminiscent of a market rollercoa

Christian W. Bauer, Craig N. Burrell

We study nonperturbative corrections to the inclusive rare decay B -> X_s l^+ l^- by performing an operator product expansion (OPE) to O(1/m_b^3). The values of the matrix elements entering at this order are unknown and introduce uncertainties into physical quantities. We study uncertainties introduced into the partially integrated rate, moments of the hadro

Sergio De Filippo

Only craziness I am ashamed about.

M. Loewe, C. Valenzuela

In the frame of the scalar theory $g ϕ^{4}$, we explore the occurrence of thermal renormalons, i. e. temperature dependent singularities in the Borel plane. The discussion of a particular renormalon type diagram at finite temperature, using Thermofield Dynamics, allows us to establish that these singularities actually get a temperature dependence. This depen

Sara R. Heap, Don J. Lindler, Thierry M. Lanz, Robert H. Cornett

We present new coronagraphic images of Beta Pictoris obtained with the Space Telescope Imaging Spectrograph (STIS) in September 1997. The high-resolution images (0.1") clearly detect the circumstellar disk as close as 0.75" to the star, corresponding to a projected radius of 15 AU. The images define the warp in the disk with greater precision and at closer r

M. Banados

Despite the nice geometrical properties of higher dimensional Chern-Simons (CS) supergravity theories these actions suffer from one major drawback, namely, their connection with the real world. After some quick remarks on three-dimensional gravity, we consider five-dimensional CS supergravity and study to what extend this theory reproduces the standard low e

Joseph L. McCauley

Econometrics is based on the nonempiric notion of utility. Prices, dynamics, and market equilibria are supposed to be derived from utility. Utility is usually treated by economists as a price potential, other times utility rates are treated as Lagrangians. Assumptions of integrability of Lagrangians and dynamics are implicitly and uncritically made. In parti

H. R. Glyde, O. Plantevin, B. Fak, G. Coddens

We have measured the dynamic structure factor of liquid 4He in Vycor using neutron inelastic scattering. Well-defined phonon-roton (p-r) excitations are observed in the superfluid phase for all wave vectors 0.3 < Q < 2.15. The p-r energies and lifetimes at low temperature (T = 0.5 K) and their temperature dependence are the same as in bulk liquid 4He. Howeve

J. Huefner, Yu. P. Ivanov, B. Z. Kopeliovich, J. Raufeisen

The mass spectrum is calculated for those dileptons which are produced in the early phase of a heavy ion collisions via the direct production NN -> (l^+)(l^-)X and via the Compton process GN -> (l^+)(l^-)X with prompt gluons radiated in preceding NN interactions. Both mechanisms produce a mass spectrum which decreases steeply with invariant mass of the l^+l^

R. Shankar

I show that the hamiltonian theory of Composite Fermions (CF) is capable of yielding a unified description in fair agreement with recent experiments on polarization P and relaxation rate 1/T_1 in quantum Hall states at filling nu = p/(2ps+1), at and near nu = 1/2 and 1/4, at zero and nonzero temperatures. I show how rotational invariance and two dimensionali

Y. Brihaye, B. Hartmann, J. Kunz

Self-gravitating SU(2) Higgs magnetic monopoles exist up to a critical value of the ratio of the vector meson mass to the Planck mass, which depends on the Higgs boson mass. At the critical value a critical solution with a degenerate horizon is reached. As pointed out by Lue and Weinberg, there are two types of critical solutions, with a transition at an int

Nicola Manini, Fabio Pistolesi

We investigate the adiabatic evolution of a set of non-degenerate eigenstates of a parameterized Hamiltonian. Their relative phase change can be related to geometric measurable quantities that extend the familiar concept of Berry phase to the evolution of more than one state. We present several physical systems where these concepts can be applied, including

A. Tschersich, K. B. Efetov

Using the supersymmetry technique, we calculate the joint distribution of local densities of electron wavefunctions in two coupled disordered or chaotic quantum billiards. We find novel spatial correlations that are absent in a single chaotic system. Our exact result can be interpreted for small coupling in terms of the hybridization of eigenstates of the is

A. P. Jauho

We review recent applications of the nonequilibrium Green function technique to time-dependent transport in mesoscopic systems.

Seok-Hwan Chung, Ali Gokirmak, Dong-Ho Wu, J. S. A. Bridgewater

We present experimental results on eigenfunctions of a wave chaotic system in the continuous crossover regime between time-reversal symmetric and time-reversal symmetry-broken states. The statistical properties of the eigenfunctions of a two-dimensional microwave resonator are analyzed as a function of an experimentally determined time-reversal symmetry brea

E. Jeckelmann, F. Gebhard, F. H. L. Essler

We combine well-controlled analytical and numerical methods to determine the optical conductivity of the one-dimensional Mott-Hubbard insulator at zero temperature. A dynamical density-matrix renormalization group method provides the entire absorption spectrum for all but very small coupling strengths. In this limit we calculate the conductivity analytically

V. G. Rostiashvili, T. A. Vilgis

The variational principle (VP) has been used to capture the metastable states of a glass-forming molecular system without quenched disorder. It has been shown that VP naturally leads to a self-consistent random field Ginzburg-Landau model (RFGLM). In the framework of one-step replica symmetry breaking (1-RSB) the general solution of RFGLM is discussed in the

Gyula Fodor, Zoltán Perjés

Circularly rotating axisymmetric perfect fluid space-times are investigated to second order in the small angular velocity. The conditions of various special Petrov types are solved in a comoving tetrad formalism. A number of theorems are stated on the possible Petrov types of various fluid models. It is shown that Petrov type II solutions must reduce to the

H. Arfaei, D. Kamani

We present a general description of two mixed branes interactions. For this we consider two mixed branes with dimensions p_1 and p_2, in external field B_{\mu\nu} and arbitrary gauge fields A^1_{\alpha_1} and A^2_{\alpha_2} on the world volume of them, in spacetime in which some of its directions are compactified on circles with different radii. Some example

I. G. Korepanov

The usual propetry of s<-->t duality for scattering amplitudes, e.g. for Veneziano amplitude, is deeply connected with the 2-dimensional geometry. In particular, a simple geometric construction of such amplitudes was proposed in a joint work by this author and S.Saito (solv-int/9812016). Here we propose analogs of one of those amplitudes associated with mult

E. Diolaiti, O. Bendinelli, D. Bonaccini, L. Close

Starfinder is an IDL code for the deep analysis of stellar fields, designed for well-sampled images with high and low Strehl factor. An important feature is represented by the possibility to measure the anisoplanatic effect in wide-field Adaptive Optics observations and exploit this knowledge to improve the analysis of the observed field. A description of th

Fiona Hoyle, Istvan Szapudi, Carlton Baugh

We present a counts-in-cells analysis of clustering in the optically selected Durham/UKST and Stromlo-APM Galaxy Redshift Surveys. Minimum variance estimates of the second moment, skewness (S_3) and kurtosis (S_4) of the count probability distribution are extracted from a series of volume limited samples of varying radial depth. The corresponding theoretical

Kiyoshi Higashijima, Muneto Nitta

Supersymmetric nonlinear sigma models are obtained from linear sigma models by imposing supersymmetric constraints. If we introduce auxiliary chiral and vector superfields, these constraints can be expressed by D-terms and F-terms depending on the target manifolds. Auxiliary vector superfields appear as gauge fields without kinetic terms. If there are no D-t

Changhao Jin

A precise determination of |V_{ub}| can be obtained exploiting the sum rule for inclusive charmless semileptonic B-meson decays. The sum rule is derived on the basis of light-cone expansion and b-flavored quantum number conservation. The sum rule does not receive any perturbative QCD correction. In this determination of |V_{ub}|, there is no perturbative QCD

Taejin Lee

We perform canonical quantization of open strings in the $D$-brane background with a $B$-field. Treating the mixed boundary condition as a primary constraint, we get a set of secondary constraints. Then these constraints are shown to be equivalent to orbifold conditions to be imposed on normal string modes. These orbifold conditions are a generalization of t

Avner Peleg, Baruch Meerson

A simple multifractal coarsening model is suggested that can explain the observed dynamical behavior of the fractal dimension in a wide range of coarsening fractal systems. It is assumed that the minority phase (an ensemble of droplets) at $t=0$ represents a non-uniform recursive fractal set, and that this set is a geometrical multifractal characterized by a

Katrin Becker, Melanie Becker

Freed, Harvey, Minasian and Moore have proposed a mechanism to cancel the gravitational anomaly of the M-theory fivebrane coming from diffeomorphisms acting on the normal bundle. This procedure is based on a modification of the conventional M-theory Chern-Simons term. We compactify this space-time interaction to the ten-dimensional type IIA theory. We then a

S. Boettcher, M. Paczuski

Numerical results are presented indicating d_c=4 as the upper critical dimension for the Bak-Sneppen evolution model. This finding agrees with previous theoretical arguments, but contradicts a recent Letter [Phys. Rev. Lett. 80, 5746-5749 (1998)] that placed d_c as high as d=8. In particular, we find that avalanches are compact for all dimensions d<=4, and a

Kris Sigurdson, Douglas Scott

The confrontation of the Cosmic Microwave Background (CMB) theoretical angular power spectrum with available data often requires the calculation of large numbers of power spectra. The standard practice is to use a fast code to compute the CMB power spectra over some large parameter space, in order to estimate likelihoods and constrain these parameters. But a