October 1999 arXiv papers — page 10

E. W. Draeger, D. M. Ceperley

The Debye-Waller factor and the mean-squared displacement from lattice sites for solid 3He and 4He were calculated with Path Integral Monte Carlo at temperatures between 5 K and 35 K, and densities between 38 nm^(-3) and 67 nm^(-3). It was found that the mean-squared displacement exhibits finite-size scaling consistent with a crossover between the quantum an

Ferenc Simon, Andras Janossy, Ferenc Muranyi, Titusz Feher

We report on the magnetic resonance of NH_3K_3C_60 powders in the frequency range of 9 to 225 GHz. The observation of an antiferromagnetic resonance below the phase transition at 40 K is evidence for an antiferromagnetically ordered ground state. In the normal state, above 40 K, the temperature dependence of the spin-susceptibilty measured by ESR agrees with

M. A. M. de Aguiar, H. S. Brandi, Belita Koiller, Eduardo R. Mucciolo

A model is investigated where a monochromatic, spatially homogeneous laser field interacts with an electron in a one-dimensional periodic lattice. The classical Hamiltonian is presented and the technique of stroboscopic maps is used to study the dynamical behavior of the model. The electron motion is found to be completely regular only for small field amplit

Pavel Exner, Hynek Kovarik

We analyze the spectrum of the "local" Iwatsuka model, i.e. a two-dimensional charged particle interacting with a magnetic field which is homogeneous outside a finite strip and translationally invariant along it. We derive two new sufficient conditions for absolute continuity of the spectrum. We also show that in most cases the number of open spectra

J. E. Han, O. Gunnarsson

Using exact diagonalzation techniques, we study a model of interacting electrons and phonons. The spectral width of the phonons is found to be reduced as the Coulomb interaction U is increased. For a system with two modes per site, we find a transfer of coupling strength from the upper to the lower mode. This transfer is reduced as U is increased. These resu

Mikko Karttunen, Mikko Haataja, K. R. Elder, Martin Grant

We model driven two-dimensional charge-density waves in random media via a modified Swift-Hohenberg equation, which includes both amplitude and phase fluctuations of the condensate. As the driving force is increased, we find that the defect density first increases and then decreases. Furthermore, we find switching phenomena, due to the formation of channels

F. de los Santos, Miguel A. Muñoz

We use field theoretic renormalization group methods to study the critical behavior of a recently proposed Langevin equation for driven lattice gases under infinitely fast drive. We perform an expansion around the upper critical dimension, $d_c=4$, and obtain the critical exponents to one loop order. The main features of the two loop calculation are also out

C. Hooley, A. M. Tsvelik

We analyse the antiferromagnetic spin-1/2 Heisenberg model on a depleted kagome lattice, where some bonds have been reduced to exchange integral J_2 << J_1. The fully depleted system consists of 1D chains, each with a doubly degenerate singlet-pair ground state and a spectral gap (like the Majumdar-Ghosh model). There are localised and itinerant low-energy e

L. Kaplan, E. J. Heller

There is much latitude between the requirements of Schnirelman&#39;s theorem regarding the ergodicity of individual high-energy eigenstates of classically chaotic systems on the one hand, and the extreme requirements of random matrix theory on the other. It seems likely that some eigenstate statistics and long-time transport behavior bear nonrandom imprints

P. Castiglione, R. Festa, A. Mazzino

Passive scalar transport in a spatially-extended background of roll convection is considered in the time-periodic regime. The latter arises due to the even oscillatory instability of the cell lateral boundary, here accounted for by sinusoidal oscillations of frequency $ω$. By varying the latter parameter, the strength of anticorrelated regions of the velocit

Piotr Garbaczewski, Robert Olkiewicz

We combine earlier investigations of linear systems with Lévy fluctuations [Physica {\bf 113A}, 203, (1982)] with recent discussions of Lévy flights in external force fields [Phys.Rev. {\bf E 59},2736, (1999)]. We give a complete construction of the Ornstein-Uhlenbeck-Cauchy process as a fully computable model of an anomalous transport and a paradigm example

Piotr Garbaczewski

We develop a general theory dealing with stochastic models for dynamical systems that are governed by various nonlinear, ordinary or partial differential, equations. In particular, we address the problem how flows in the random medium (related to driving velocity fields which are generically bound to obey suitable local conservation laws) can be reconciled w

P. Cinzano, F. Falchi, C. D. Elvidge, K. E. Baugh

We present the map of the artificial sky brightness in Europe in V band with a resolution of approximately 1 km. The aim is to understand the state of night sky pollution in Europe, to quantify the present situation and to allow future monitoring of trends. The artificial sky brightness in each site at a given position on the sky is obtained by integration o

M. A. Guerrero, E. Villaver, A. Manchado, P. Garcia-Lario

We present near-IR narrow-band continuum-subtracted images in the H$_2$ $2.122μ$m, and Br$γ$ $2.166μ$m emission lines for a sample of 15 bipolar planetary nebulae. H$_2$ emission was definitely detected for most of the objects in this sample (13 out of 15). The very high H$_2$ detection rate supports the idea that bipolar planetary nebulae have important res

Jenny Westin, Christopher Sneden, Bengt Gustafsson, John J. Cowan

New high resolution, very high signal-to-noise spectra of ultra-metal-poor (UMP) giant stars HD 115444 and HD 122563 have been gathered with the High-Resolution Echelle Spectrometer of the McDonald Observatory 2.7m Telescope. With these spectra, line identification and model atmosphere analyses have been conducted, emphasizing the neutron-capture elements. T

R. W. Pogge, D. Maoz, L. C. Ho, M. Eracleous

LINERs exist in the nuclei of a large fraction of luminous galaxies, but their connection with the AGN phenomenon has remained elusive. We present Hubble Space Telescope narrowband [O III]5007 and H-alpha+[N II] emission-line images of the central regions of 14 galaxies with LINER nuclei. The compact, ~1 arcsec-scale, unresolved emission that dominates the l

Nasreen Haque, Anil K. Pradhan

Relativistic and resonance effects in the photoionization of Mg-like Fe~XV are investigated using the Breit-Pauli R-matrix Method (BPRM) at near-threshold and intermediate energies, complemented by the Relativistic Random Phase Approximation (RRPA) and multi-channel quantum defect theory in the energy region up to the L-shell ionization thresholds. The cross

Hong Lin Zhang, Anil K. Pradhan

Photoionization cross sections and recombination rate coefficients are presented for the L-shell ground state fine structure levels $2s^22p^4 \ ^3P_{2,0,1}$ of Fe~XIX. Several sets of calculations including relativistic effects are carried out: (i) Breit-Pauli R-matrix (BPRM), (ii) Relativistic Distorted Wave (RDW), and (iii) a semi-relativistic calculation.

Anatoly Klypin, Andrey V. Kravtsov, Pedro Colin

We give a summary of our recent studies of spatial and velocity biases of galaxy-size halos in cosmological models. Recent progress in numerical techniques made it possible to simulate halos in large volumes with a such accuracy that halos survive in dense environments of groups and clusters of galaxies. Dark matter halos in simulations look like real galaxi

Fridolin Weber

Gravity compresses the matter in the cores of neutron stars to densities which are significantly higher than the density of ordinary atomic nuclei, thus providing a high-pressure environment in which numerous particle processes - from the generation of new baryonic particles to quark deconfinement to the formation of Boson condensates and H-matter - may comp

M. Hilker, T. Richtler

A revised metallicity calibration of the Stroemgren (b-y),m_1 diagram, based on a sample of globular cluster and field red giant stars, is presented. This new calibration has been used to determine Stroemgren metallicities ([Fe/H]_phot) for more than 1400 red giants in omega Centauri. Most of the stars belong to a metal poor ([Fe/H]_phot = -1.7 dex), old pop

R. J. Sylvester, F. Kemper, M. J. Barlow, T. de Jong

Infrared spectra of a number of evolved O-rich stars have been obtained with the Short- and Long- Wavelength spectrometers on board the Infrared Space Observatory. The very broad wavelength coverage (2.4-197 micron) obtained by combining observations made with the two spectrometers includes practically all of the flux emitted by the sources, and allows us to

N. J. Haigh, M. J. Coe, I. A. Steele, J. Fabregat

This paper presents observations of the Be/X-ray binary system A0535+26 revealing the first observed loss of its circumstellar disc, demonstrated by the loss of its JHK infrared excess and optical/IR line emission. However optical/IR spectroscopy reveals the formation of a new inner disc with significant density and emission strength at small radii; the disc

L. Van Waerbeke, F. Bernardeau, K. Benabed

The low redshift structures of the Universe act as lenses in a similar way on the Cosmic Microwave Background light and on the distant galaxies (say at redshift about unity). As a consequence, the CMB temperature distortions are expected to be statistically correlated with the galaxy shear, exhibiting a non-uniform distribution of the relative angle between

Michel Tagger

We present an instability, occurring in the inner region of magnetized accretion disks, which seems to be a good candidate to explain the low-frequency QPO observed in many X-ray binaries. We then briefly show how, in the remarkable case of the microquasar GRS 1915+105, identifying this QPO with our instability leads to a scenario for the $\sim$ 30 mn cycles

Jongsoo Kim, Jose Franco, S. S. Hong, Alfredo Santillan

A linear stability analysis of a multi-component and magnetized Galactic disk model is presented. The disk model uses the observed stratifications for the gas density and gravitational acceleration at the solar neighborhood and, in this sense, it can be called a realistic model. The distribution of the total gas pressure is defined by these observed stratifi

H. Böhringer, G. Soucail, Y. Mellier, Y. Ikebe

The paper reports the analysis of a very deep ROSAT HRI observation of the distant lensing cluster, CL0024+17. The morphology of the cluster is studied and the small core radius inferred from lensing analysis is confirmed. Constraints on the mass distribution are discussed.

Michael S. Briggs

The evidence for spectral features in gamma-ray bursts is summarized. As a guide for evaluating the evidence, the properties of gamma-ray detectors and the methods of analyzing gamma-ray spectra are reviewed. In the 1980&#39;s, observations indicated that absorption features below 100 keV were present in a large fraction of bright gamma-ray bursts. There wer

P. J. de Naray, W. N. Brandt, J. P. Halpern, K. Iwasawa

The nearby barred spiral galaxy NGC 1672 shows dramatic starburst activity and may also host a Seyfert 2 nucleus. We present new X-ray observations that set constraints on starburst and Seyfert activity in NGC 1672. Two ROSAT HRI exposures, taken in 1992 and 1997, are used to investigate long-term variability of the known X-ray sources and to search for new

Risa H. Wechsler, James S. Bullock, Rachel S. Somerville, Tsafrir Kolatt

We investigate the clustering properties of high-redshift galaxies within three competing scenarios for assigning luminous galaxies to dark matter halos from N-body simulations: a one galaxy per massive halo model, a quiescent star formation model, and a collisional starburst model. We compare these models to observations of Lyman-Break galaxies at z~3$ With

J. H. Fan, G. Z. Xie, R. Bacon

In this paper, The central black hole masses and the Doppler factors are derived for PKS 0528+134, PKS 0537-441, 3C279, PKS 1406-074, PKS 1622-297, Q1633+382, Mkn 501, and BL Lacertae. The masses obtained are in the range of (1 -7)$\times 10^{7}M_{\odot}$ and compared with that obtained with the Klein-Nishina cross section considered (Dermer & Gehrels 1995).

G. Gregori, Francesco Miniati, Dongsu Ryu, T. W. Jones

We present results from the first three-dimensional numerical simulations of moderately supersonic cloud motion through a tenuous, magnetized medium. We show that the interaction of the cloud with a magnetic field perpendicular to its motion has a great dynamical impact on the development of instabilities at the cloud surface. Even for initially spherical cl

G. Lagache, J. L. Puget

We have used the Marano1 field observations with ISOPHOT at 170 $μ$m to search for the Cosmic Far-InfraRed Background fluctuations. This field is part of the FIRBACK project (Puget et al., 1999a). For the first time, fluctuations due to unresolved extra-Galactic sources are isolated. The emission of such sources clearly dominates, at arcminute scales, the ba

Cristiano Porciani, Piero Madau

Ongoing searches for supernovae (SNe) at cosmological distances have recently started to provide large numbers of events with measured redshifts and apparent brightnesses. Compared to quasars or galaxies, Type Ia SNe represent a population of sources with well-known intrinsic properties, and could be used to detect gravitational lensing even in the absence o

Matthias R Gaberdiel

A comprehensive introduction to two-dimensional conformal field theory is given.

D. V. Alekseevsky, V. Cortés, C. Devchand

We introduce the notion of a special complex manifold: a complex manifold (M,J) with a flat torsionfree connection \nabla such that (\nabla J) is symmetric. A special symplectic manifold is then defined as a special complex manifold together with a \nabla-parallel symplectic form ω. This generalises Freed&#39;s definition of (affine) special Kähler manifolds

Shaaban Khalil

The cosmological relic density of the lightest supersymmetric particle (LSP) of type I string derived model is calculated. This model can accommodate large values of CP violating phases, and the electron and neutron electric dipole moments satisfy the experimental constraint. We show that the constraint from the electric dipole moment on the ratio between th

V M Kendon

A new scaling theory for spinodal decomposition in the inertial hydrodynamic regime is presented. The scaling involves three relevant length scales, the domain size, the Taylor microscale and the Kolmogorov dissipation scale. This allows for the presence of an inertial &#34;energy cascade&#34;, familiar from theories of turbulence, and improves on earlier sc

Hiroshi Goda, Martin Scharlemann, Abigail Thompson

It is a consequence of theorems of Gordon-Reid [Tangle decompositions of tunnel number one knots and links, J. Knot Theory and its Ramifications, 4 (1995) 389-409] and Thompson [Thin position and bridge number for knots in the 3-sphere, Topology, 36 (1997) 505-507] that a tunnel number one knot, if put in thin position, will also be in bridge position. We sh

Y. F. Gu, X. H. Li

The so-called ρπpuzzle of Jψand ψ(2S) decays is examined using the experimental data available to date. Two different approaches were taken to estimate the ratio of Jψand ψ(2S) hadronic decay rates. While one of the estimates could not yield the exact ratio of ψ(2S) to Jψinclusive hadronic decay rates, the other, based on a computation of the inclusive ggg d

W. Cassing, S. Juchem

The transport of hadrons with dynamical spectral functions A_h(X,\vec{P},M^2) is studied for nucleus-nucleus collisions at SIS and AGS energies in comparison to the conventional quasi-particle limit and the available experimental data within the recently developed off-shell HSD transport approach. Similar to reactions at GANIL energies the off-shell effects

Arjun Berera

Two mechanisms are examined for hard double pomeron exchange dijet production, the factorized model of Ingelman-Schlein and the nonfactorized model of lossless jet production which exhibits the Collins-Frankfurt-Strikman mechanism. Comparison between these two mechanisms are made of the total cross section, $E_T$-spectra, and mean rapidity spectra. For both

A. A. Babich, P. Osland, A. A. Pankov, N. Paver

For the processes e+e-\to μ+μ-, τ+τ-, b\bar{b} and c\bar{c} at a future e+e- collider with \sqrt{s}=0.5 TeV, we examine the sensitivity of the helicity cross sections to four-fermion contact interactions. If longitudinal polarization of the electron beam were available, two polarized integrated cross sections would offer the opportunity to separate the helic

Haye Hinrichsen

Directed percolation is one of the most prominent universality classes of nonequilibrium phase transitions and can be found in a large variety of models. Despite its theoretical success, no experiment is known which clearly reproduces the critical exponents of directed percolation. The present work compares suggested experiments and discusses possible reason

M. Servin, G. Brodin, M. Bradley, M. Marklund

We consider the parametric excitation of Alfven waves by gravitational radiation propagating on a Minkowski background, parallel to an external magnetic field. As a starting point, standard ideal MHD equations incorporating the curvature of space-time has been derived. The growth rate of the Alfven waves has been calculated, using the normal mode approach. V

K. Park, J. K. Jain

It is argued that the composite fermion liquid is a promising candidate for an observation of the elusive, interaction driven magnetization first proposed by Bloch seven decades ago. In analogy to what is theoretically believed to be the case for the idealized electron gas in zero magnetic field, this spontaneously broken symmetry phase is predicted to occur

Murat Özer

We first investigate the form the General Relativity Theory would have taken had the gravitational mass and the inertial mass of material objects been different. We then extend this analysis to electromagnetism and postulate an equivalence principle for the electromagnetic field. We argue that to each particle with a different electric charge-to-mass ratio i

J. Rozynek, G. Wilk

We have extended recently proposed model of parton distribution i nucleons to the case of nucleons in nuclei.

G. J. Gounaris, J. Layssac, F. M. Renard

The possible form of New Physics (NP) interactions affecting the ZZZ, $ZZ γ$ and $Zγγ$ vertices, is critically examined. Their signatures and the possibilities to study them, through ZZ and $Zγ$ production, at the e^-e^+ Colliders LEP and LC and at the hadronic Colliders Tevatron and LHC, are investigated. Experimental limits obtained or expected on each cou

A. E. Allahverdyan, V. G. Gurzadyan

The relation between the thermodynamical and cosmological arrows of time is usually viewed in the context of the initial conditions of the Universe. It is a necessary but not sufficient condition for ensuring the thermodynamical arrow. We point out that in the Friedmann-Robertson-Walker Universe with negative curvature, k=-1, there is the second necessary in

G. Kälbermann

If our visible universe is considered a trapped shell in a five-dimensional hyper-universe, all matter in it may be connected by superluminal signals traveling through the fifth dimension. Events in the shell are still causal, however, the propagation of signals proceeds at different velocities depending on the fifth coordinate.

D. K. Park, H. J. W. Müller-Kirsten, J. -Q. Liang

Winding number transitions from quantum to classical behavior are studied in the case of the {1+1} dimensional Mottola-Wipf model with the space coordinate on a circle for exploring the possibility of obtaining transitions of second order. The model is also studied as a prototype theory which demonstrates the procedure of such investigations. In the model at

Alfredo Aranda, Christopher D. Carone, Richard F. Lebed

We present a model of fermion masses based on a minimal, non-Abelian discrete symmetry that reproduces the Yukawa matrices usually associated with U(2) theories of flavor. Mass and mixing angle relations that follow from the simple form of the quark and charged lepton Yukawa textures are therefore common to both theories. We show that the differing represent

Marcelo A. Marchiolli, Salomon S. Mizrahi, Victor V. Dodonov

Here we consider the Husimi function P for the squeezed states and calculate the marginal and correlation distribution functions when P is projected onto the photon number states. According to the value of the squeezing parameter one verifies the occurence of oscillations and beats as already appointed in the literature. We verify that these phenomena are en

Y. Strauss, L. P. Horwitz

We apply the quantum Lax-Phillips scattering theory to a relativistically covariant quantum field theoretical form of the (soluble) Lee model. We construct the translation representations with the help of the wave operators, and show that the resulting Lax-Phillips $S$-matrix is an inner function (the Lax-Phillips theory is essentially a theory of translatio

Dorit Aharonov

The fundamental problem of the transition from quantum to classical physics is usually explained by decoherence, and viewed as a gradual process. The study of entanglement, or quantum correlations, in noisy quantum computers implies that in some cases the transition from quantum to classical is actually a phase transition. We define the notion of entanglemen

Yoon-Ho Kim, Yanhua Shih

An entangled pair of photons (1 and 2) are emitted to opposite directions. A narrow slit is placed in the path of photon 1 to provide precise knowledge of its position on the $y$ axis and this also determines the precise $y$ position of its twin, photon 2, due to quantum entanglement. Is photon 2 going to experience a greater uncertainty in momentum, i.e., a

J. Ortner, V. M. Rylyuk

Nonlinear relativistic ionization phenomena induced by a strong linearly polarized laser field are considered. The starting point is the classical relativistic action for a free electron moving in the electromagnetic field created by a strong laser beam. This action has been used to calculate semiclassical transition rates. Simple analytical expressions for

Dennis Silverman

Bayesian Poisson probability distributions for the average n can be analytically converted into equivalent chi-squared distributions. These can then be combined with other Gaussian or Bayesian Poisson distributions to make a total chi-squared distribution. This allows the usual treatment of chi-squared contours but now with both Poisson and Gaussian statisti

Serge F. Mingaleev, Yuri B. Gaididei, Franz G. Mertens

We study the influence of long-range interatomic interactions on the properties of supersonic pulse solitons in anharmonic chains. We show that in the case of ultra-long-range (e.g., screened Coulomb) interactions three different types of pulse solitons coexist in a certain velocity interval: one type is unstable but the two others are stable. The high-energ

G. A. Miller

Understanding an important class of experiments requires that light-front dynamics and related light cone variables k^+ and k_perp be used. If one uses k^+ as a momentum variable, the corresponding canonical spatial variable is x^-=x^0-x^3 and the time variable is x^0+x^3. This is the light front (LF) approach of Dirac. A relativistic light front formulation

Nir Barnea, Timothy S. Walhout

We study in further detail a nontopological soliton model with coupling between quarks and mesons selected as promising in the previous work. Here we go beyond the Wigner-Seitz approximation by introducing the disorder necessary to reproduce the liquid state. We study nuclear matter, with particular interest in the transition to a quark-gluon plasma. The mod

Nir Barnea, Timothy S. Walhout

A system of nontopological solitons interacting through scalar and vector meson exchange is used to model nuclear matter. The models studied are of the Friedberg-Lee type, which exhibit dynamical bag formation due to the coupling of quarks to a scalar composite gluon field. It is shown that the chiral chromodielectric model gives the best fit to the empirica

F. M. Lev, E. Pace, G. Salme`

The deuteron magnetic and quadrupole moments are unambiguosly determined within the front-form Hamiltonian dynamics, by using a new current operator which fulfills Poincaré, parity and time reversal covariance, together with hermiticity and the continuity equation. For both quantities the usual disagreement between theoretical and experimental results is lar

A. N. Ivanov, H. Oberhummer, N. I. Troitskaya, M. Faber

The astrophysical factor S_pp(0) for the solar proton burning, p + p -> D + positron + neutrino, is recalculated in the relativistic field theory model of the deuteron (RFMD). We obtain S_pp(0) = 4.08 x 10^{-25} MeV b which agrees good with the recommended value S_pp(0) = 4.00 x 10^{-25} MeV b. The amplitude of low-energy elastic proton-proton (pp) scatterin

M. R. Grasselli, R. F. Streater

Let H be a self-adjoint operator bounded below by 1, and let V be a small form perturbation such that RVS has finite norm, where R is the resolvent at zero to the power 1/2 +epsilon, and S is the resolvent to the power 1/2-epsilon. Here, epsilon lies between 0 and 1/2. If the Gibbs state defined by H is sufficiently regular, we show that the free energy is a

Omar Mustafa, Thabit Barakat

With the aid of a modified similarity transformation we obtained exact energy eigenvalues of the generalized Dirac-Coulomb equation. This equation consists of the time component of the Lorentz 4-vector potential V_v(r)=-A_1/r, and a Lorentz scalar potential V_s(r)=-A_2/r. The transformed radial equations are so simple that their solutions are inferred from t

P. Exner, H. Grosse

This text is a part of an unfinished project which deals with the generalized point interaction (GPI) in one dimension. We employ two natural parametrizations, which are known but have not attracted much attention, to express the resolvent of the GPI Hamiltonian as well as its spectral and scattering properties. It is also shown that the GPI yields one of th

Thabit Barakat, Maen Odeh, Omar Mustafa

A shifted - l expansion technique is introduced to calculate the energy eigenvalues for Klein-Gordon (KG) equation with Lorentz vector and/or Lorentz scalar potentials. Although it applies to any spherically symmetric potential, those that include Coulomb-like terms are only considered. Exact eigenvalues for a Lorentz vector or a Lorentz scalar, and an equal

Omar Mustafa, Maen Odeh

We propose a new analytical method to solve for the nonexactly solvable Schrodinger equation. Successfully, it is applied to a class of spiked harmonic oscillators and truncated Coulomb potentials. The utility of this method could be extended to study other systems of atomic, molecular and nuclear physics interest.

Laurent Bartholdi, Rostislav I. Grigorchuk

We give the first example of a connected 4-regular graph whose Laplace operator's spectrum is a Cantor set, as well as several other computations of spectra following a common ``finite approximation'' method. These spectra are simple transforms of the Julia sets associated to some quadratic maps. The graphs involved are Schreier graphs of fractal groups of i

Kefeng Liu

In this note we apply heat kernels to derive some localization formula in sympletcic geometry, to study moduli spaces of flat connections on a Riemann surface, to obtain the push-forward measures for certain maps between Lie groups and to solve equations in finite groups.

Zhongmin Shen

We study the following problem: given an Einstein metric on a manifold, characterize and study all Einstein metrics which are pointwise projective to the given one. By definition, two metrics are said to be pointwise projectively related if they have the same geodesics as point sets. This is closely related to Hilbert&#39;s Fourth Problem. In this paper, we

Andras Vasy, Maciej Zworski

In this note we obtain semiclassical resolvent estimates for non-trapping long range perturbations of the Laplacian on asymptotically Euclidean manifolds. Our proof is based on a positive commutator argument which differs from Mourre-type estimates by making the commutant also positive. The resolvent estimates, including the weighting of the Sobolev spaces i

A. Zabrodin

We review recent results on the finite-gap properties of difference operators with elliptic coefficients and give explicit characterization of spectral curves for difference analogues of the higher Lamé operators. This curve parametrizes double-Bloch solutions to the difference Lamé equation. The curve depends on a positive integer number \ell, related to it

Helmut Prodinger

Up-down permutations are counted by tangent resp. secant numbers. Considering words instead, where the letters are produced by independent geometric distributions, there are several ways of introducing this concept; in the limit they all coincide with the classical version. In this way, we get some new q-tangent and q-secant functions. Some of them also have

V. K. Kharchenko, Jaime Keller, S. Rodriguez-Romo

A complete classification is given of all inner actions on the Clifford algebra C(1,3) defined by representations of the quantum group GL_q(2,C), q^m\neq 1, which are not reduced to representations of two commuting &#34;q-spinors&#34;. As a consequence of this classification it is shown that the space of invariants of every GL_q(2,C)-action of this type, whi

Igor Rivin

We obtain sharp bounds for the number of n-cycles in a finite graph as a function of the number of edges, and prove that the complete graph is optimal in more ways than could be imagined. En route, we prove some sharp estimates on power sums.

Bruce Landman, Aaron Robertson

Van der Waerden&#39;s classical theorem on arithmetic progressions states that for any positive integers k and r, there exists a least positive integer, w(k,r), such that any r-coloring of {1,2,...,w(k,r)} must contain a monochromatic k-term arithmetic progression {x,x+d,x+2d,...,x+(k-1)d}. We investigate the following generalization of w(3,r). For fixed pos

Atsushi Moriwaki

This paper is the sequel of our paper &#34;Arithmetic height functions over finitely generated fields&#34; (cf. math.NT/9809016). In this paper, we define the canonical height of subvarieties of an abelian variety over a finitely generated field over Q. We also prove that the canonical height of a subvariety is zero if and only if it is a translation of an a

Martin Engman

An upper bound on the first S^1 invariant eigenvalue of the Laplacian for invariant metrics on the 2-sphere is used to find obstructions to the existence of isometric embeddings of such metrics in (R^3,can). As a corollary we prove: If the first four distinct eigenvalues have even multiplicities then the surface of revolution cannot be isometrically embedded

Angel M. Uranga

We discuss the consistency conditions of a novel orientifold projection of type IIB string theory on C^2/Z_N singularities, in which one mods out by the combined action of world-sheet parity and a geometric operation which exchanges the two complex planes. The field theory on the world-volume of D5-brane probes defines a family of six-dimensional RG fixed po

C. G. Beneventano, M. De Francia, K. Kirsten, E. M. Santangelo

We study the effect of a background flux string on the vacuum energy of massive Dirac fermions in 2+1 dimensions confined to a finite spatial region through MIT boundary conditions. We treat two admissible self-adjoint extensions of the Hamiltonian and compare the results. In particular, for one of these extensions, the Casimir energy turns out to be discont

Christian Rupp

We investigate the superconformal transformation properties of the supercurrent as well as of the superconformal anomalies themselves in d=4, N=1 supersymmetric quantum field theory. Matter supercurrent and anomalies are coupled to a classical background of minimal supergravity fields. On flat superspace, there exist two different types of the superconformal

Tsunehiro Kobayashi

Equivalence in physics is discussed on the basis of experimental data accompanied by experimental errors. The introduction of the equivalence being consistent with the mathematical definition is possible only in theories constructed on non-standard number spaces by taking the experimental errors as infinitesimal numbers of the non-standard spaces. Following

J. Engel, P. Vogel

We consider the potential benefits of searching for supersymmetric dark-matter through its inelastic excitation, via the &#34;scalar current&#34;, of low-lying collective nuclear states in a detector. If such states live long enough so that the gamma radiation from their decay can be separated from the signal due to nuclear recoil, then background can be dra

H. Casini, J. C. D&#39;Olivo, R. Montemayor

We study the solar neutrino problem within the framework of a parametrized post-Newtonian formulation for the gravitational interaction of the neutrinos, which incorporates a violation to the equivalence principle (VEP). Using the current data on the rates and the energy spectrum we find two possible oscillation solutions, both for a large mixing angle. One

John Ellis

The prospects for the coming Golden Age of heavy-flavour physics are discussed from the perspective of one who hopes it may provide a window onto physics beyond the Standard Model. Precise QCD calculations are necessary for accurate determinations of CKM parameters, and may be provided by the lattice and new perturbative techniques. The future of CKMology in

Jonny Lundell, Hakan Snellman

We clarify the domain needed for the mixing angles in three flavor neutrino oscillations. By comparing the ranges of the transition probabilities as functions of the domains of the mixing angles, we show that it is necessary and sufficient to let all mixing angles be in $[ 0, π/2 ]$. This holds irrespectively of any assumptions on the neutrino mass squared d

Martin Lavelle, David McMullan

Descriptions of hadrons and glueballs can be constructed using strings to preserve gauge invariance. We show how this string dependence may be removed to all orders in perturbation theory.

M. Knecht, S. Peris, E. de Rafael, .

We report on some recent progress made in understanding weak matrix elements of mesons in the context of the next-to-leading order of the large-Nc approximation to QCD. Specifically, we first use the example of the weak contributions to the pi^+ - pi^0 mass difference to exhibit how a systematic matching can be achieved analytically between short distances a

Yue-Liang Wu

After presenting an optimistic prediction for the CP-violating parameter $ε&#39;/ε$ in the standard model, we provide an analysis on new physics effects in $ε&#39;/ε$.

Sh. Matsumoto, M. Yoshimura

A standard calculation of the energy density of heavy stable particles that may pair-annihilate into light particles making up thermal medium is performed to second order of coupling, using the technique of thermal field theory. At very low temperatures a power law of temperature is derived for the energy density of the heavy particle. This is in sharp contr

Alex Krasnitz, Raju Venugopalan

At very high energies, weak coupling, non-perturbative methods can be used to study classical gluon production in nuclear collisions. One observes in numerical simulations that after an initial ``formation&#39;&#39; time, the produced partons are on shell, and their subsequent evolution can be studied using transport theory. At the initial formation time, a

Ya. I. Azimov

Strangeness oscillations in decays of neutral kaons are suggested to be used as an analyzer to investigate detailed properties of heavy flavor hadrons and their decays. Here we briefly explain why, where, and to what problems this approach may be applied.

B. Abbott

We have searched for second generation leptoquark (LQ) pairs in the μμ+jets channel using 94+-5 pb^{-1} of pbar-p collider data collected by the D0 experiment at the Fermilab Tevatron during 1993-1996. No evidence for a signal is observed. These results are combined with those from the μν+jets and νν+jets channels to obtain 95% confidence level (C.L.) upper

The SELEX Collaboration, M. Iori

The SELEX experiment (E781) is 3-stage magnetic spectrometer for a high statistics study of hadroproduction of charm baryons out to large x_F using 650 Gev Sigma-, pi- and p beams. The main features of the spectrometer are: a high precision silicon vertex system, powerful particle identification provided by TRD and RICH, forward Lambda decay spectrometer and

ZEUS Collaboration

Elastic and proton-dissociative photoproduction of $ρ^0$, $ϕ$ and $J/ψ$ vector mesons ($γp\to Vp$, $γp\to VN$, respectively) have been measured in e^+p interactions at HERA up to -t=3 GeV$^2$, where t is the four-momentum transfer squared at the photon-vector meson vertex. The analysis is based on a data sample in which photoproduction reactions were tagged

Harvey R. Brown, Oliver Pooley

The purpose of this paper is to evaluate the `Lorentzian pedagogy&#39; defended by J.S. Bell in his essay ``How to teach special relativity&#39;&#39;, and to explore its consistency with Einstein&#39;s thinking from 1905 to 1952. Some remarks are also made in this context on Weyl&#39;s philosophy of relativity and his 1918 gauge theory. Finally, it is argued

B. B. Beard, V. Chudnovsky, P. Keller-Marxer

We present numerical results for the antiferromagnetic Heisenberg model (AFHM) that definitively confirm that chiral perturbation theory, corrected for cutoff effects in the AFHM, leads to a correct field-theoretical description of the low-temperature behavior of the spin correlation length for spins $S \geq 1/2$. With two independent quantum Monte Carlo alg