April 1998 arXiv papers — page 15

Tsunehide Kuroki

The O(N) symmetric vector model is considered on both ordinary and fuzzy sphere. It is shown that in both cases master fields exist and their explicit forms are presented. They are found to mix the internal symmetry and the (fuzzy) space-time symmetry. It is also argued that the cutoff brought by the fuzzy sphere plays an essential role in constructing the m

T. Gannon, M. A. Walton

New heterotic modular invariants are found using the level-rank duality of affine Kac-Moody algebras. They provide strong evidence for the consistency of an infinite list of heterotic Wess-Zumino-Witten (WZW) conformal field theories. We call the basic construction the dual-flip, since it flips chirality (exchanges left and right movers) and takes the level-

Paolo Di Vecchia

In these lectures we present a detailed description of various aspects of gauge theories with extended N=2 and N=4 supersymmetry that are at the basis of recently found exact results. These results include the exact calculation of the low energy effective action for the light degrees of freedom in the N=2 super Yang-Mills theory and the conjecture, supported

Tianjun Li

We discuss dilaton and Moduli dominant SUSY breaking scenarios in M-theory. In addition, for the nonperturbative superpotential from gaugino condensation, we discuss the soft terms in the simplest model (only S and T moduli fields) and in the $T^6/Z_{12}$ model from M-theory. From the phenomenology consideration, we suggest massless scalar SUSY breaking scen

James D. Wells

Supersymmetry is perhaps most effectively probed at the Tevatron through production and decay of weak gauginos. Most of the analyses of weak gaugino observables require electrons or muons in the final state. However, it is possible that the gauginos will decay primarily to tau leptons, thus complicating the search for supersymmetry. The motivating reasons fo

D. de Florian, R. Sassot

We present a combined QCD analysis of recent data produced by the H1 and ZEUS collaborations on the diffractive and leading-proton deep inelastic positron--proton scattering structure functions, $F_2^{D(3)}$ and $F_2^{LP(3)}$, respectively. It is shown that the QCD framework for semi-inclusive processes, based on fracture functions, allows a unified treatmen

B. L. Ioffe

The review of current experimental situation in the measurements of the first moment $Γ_{p,n}$ of spin dependent nucleon structure functions $g_{1;p,n}(x,Q^2)$ is presented. The results of the calculations of twist-4 corrections to $Γ_{p,n}$ are discussed and their accuracy is estimated. The part of the proton spin $Σ$ carried by $u, d, s$ quarks is calculat

M. Laine, M. Shaposhnikov

In theories with low energy supersymmetry breaking, the effective potential for squarks and sleptons has generically nearly flat directions, V(phi) ~ M^4 (log(phi/M))^n. This guarantees the existence of stable non-topological solitons, Q-balls, that carry large baryon number, B >> (M/m_p)^4, where m_p is the proton mass. We study the behaviour of these objec

Jose Ramon Espinosa, Mariano Quiros

We consider general supersymmetric models with: a) arbitrary matter content; and, b) gauge coupling Unification near the String scale $\sim 10^{17}$ GeV, and derive the absolute upper limit on the mass of the lightest Higgs boson. For a top-quark mass $M_t$= 175 GeV, and depending on the supersymmetric parameter $\tanβ$, this mass bound can be as high as $\s

A. Cucchieri, T. Mendes, R. Petronzio

We make a comparison between our quenched-hadron-spectroscopy results for the non-perturbatively-improved Wilson action and the corresponding unimproved case, at beta=6.2 on the same set of gauge configurations. Within our statistics, we find a sizeable improvement for the baryon spectrum and for the determination of the strange-quark mass.

K. Kanaya

In these lectures, we introduce finite temperature QCD on the lattice to non-experts of the subject. We first formulate lattice QCD both at zero and finite temperatures. Then a section is devoted to the topic of improved lattice actions which are becoming an essential ingredient of precision studies of QCD on the lattice. We then discuss about finite tempera

Y. Iwasaki, K. Kanaya, S. Kaya, S. Sakai

We investigate the phase structure of lattice QCD for general number of flavors $N_F$. Based on numerical data combined with the results of the perturbation theory we propose the following picture: When $N_F \ge 17$, there is only one IR fixed point at vanishing gauge coupling, i.e., the theory in the continuum limit is trivial. On the other hand, when $16 \

U. Guenther, A. Zhuk

Multidimensional cosmological models in the presence of a bare cosmological constant and a perfect fluid are investigated under dimensional reduction to 4-dimensional effective models. Stable compactification of the internal spaces is achieved for a special class of perfect fluids. The external space behaves in accordance with the standard Friedmann model. N

Subhendra Mohanty, A. R. Prasanna

In the wave equation obeyed by electromagnetic fields in curved spacetime there are Riemann and Ricci curvature coupling terms to the photon polarisation, which result in a polarisation dependent deviation of the photon trajectories from null geodesics. Photons are found to have an effective mass in an external gravitational field and their velocity in an in

Hideo Iguchi, Ken-ichi Nakao, Tomohiro Harada

The motion of a spherical dust cloud is described by the Lemaitre-Tolman-Bondi solution and is completely specified by initial values of distributions of the rest mass density and specific energy of the dust fluid. From generic initial conditions of this spherically symmetric collapse, there appears a naked singularity at the symmetric center in the course o

Helmut Friedrich

The intimate relations between Einstein's equation, conformal geometry, geometric asymptotics, and the idea of an isolated system in general relativity have been pointed out by Penrose many years ago. A detailed analysis of the interplay of conformal geometry with Einstein's equation allowed us to deduce from the conformal properties of the field equ

S. W. Hawking, Neil Turok

We comment on Linde's claim that one should change the sign in the action for a Euclidean instanton in quantum cosmology, resulting in the formula $P \sim e^{+S}$ for the probability of various classical universes. There are serious problems with doing so. If one reverses the sign of the action of both the instanton and the fluctuations, the latter are u

P. Di Francesco

We address the problem of "phantom" folding of the tethered membrane modelled by the two-dimensional square lattice, with bonds on the edges and diagonals of each face. Introducing bending rigidities $K_1$ and $K_2$ for respectively long and short bonds, we derive the complete phase diagram of the model, using transfer matrix calculations. The latter

Fu Chun Zhang, Kwai-Kong Ng

We use a local model to study the formation and the structure of the low energy charge transfer excitations in the insulating Cu-O$_2$ plane. The elementary excitation is a bound exciton of spin singlet, consisting of a Cu$^+$ and a neighboring spin singlet of Cu-O holes. The exciton can move through the lattice freely without disturbing the antiferromagneti

Kristian Lindgren, Cristopher Moore, Mats G. Nordahl

In dynamical systems such as cellular automata and iterated maps, it is often useful to look at a language or set of symbol sequences produced by the system. There are well-established classification schemes, such as the Chomsky hierarchy, with which we can measure the complexity of these sets of sequences, and thus the complexity of the systems which produc

Kyungwha Park, David A. Huse

We investigate the stability of the square vortex lattice which has been recently observed in experiments on the borocarbide family of superconductors. Taking into account the tetragonal symmetry of these systems, we add fourfold symmetric fourth-derivative terms to the Ginzburg-Landau(GL) free energy. At $H_{c2}$ these terms may be treated perturbatively to

M. J. Manfra, B. B. Goldberg, L. Pfeiffer, K. West

We report an anomalous doublet structure and low-energy satellite in the magneto-photoluminescence spectra of a two-dimensional electron system. The doublet structure moves to higher energy with increasing magnetic field and is most prominent at odd filling factors 5 and 3. The lower-energy satellite peak tunes to lower energy for increasing magnetic field b

Romualdo Pastor-Satorras, Daniel H. Rothman

We present a stochastic equation to model the erosion of topography with fixed inclination. The inclination causes the erosion to be anisotropic. A zero-order consequence of the anisotropy is the dependence of the prefactor of the surface height-height correlations on direction. The lowest higher-order contribution from the anisotropy is studied by applying

N. Schopohl

A new parametrisation of the Eilenberger equations of superconductivity in terms of the solutions to a scalar differential equation of the Riccati type is introduced. It is shown that the quasiclassical propagator, and in particular the local density of states, may be reconstructed, without explicit knowledge of any eigenfunctions and eigenvalues, by solving

U. Müssel, H. Rieger

In a recent letter [PRL 78 (1997) 4581] Kob and Barrat reported results of their molecular dynamics simulation of the non-equilibrium dynamics of a binary Lennard-Jones glass. They propose an aging scenario in this system that is close to a t/t_w scaling behavior. In this comment we present new results and show that a different aging scenario, known under th

N. Destainville

The tilings of lozenges in 2 dimensions and of rhomboedra in 3 dimensions are studied when they are constrained by fixed boundary conditions. We establish a link between those conditions and free or periodic boundary ones: the entropy is written as a functional integral which is treated via a saddle-point method. Then we can exhibit the dominant states of th

Johann Kroha, Peter Woelfle

The question of Fermi liquid vs. non-Fermi liquid behavior induced by strong correlations is one of the prominent problems in metallic local moment systems. As standard models for such systems, the SU(N) x SU(M) Anderson impurity models exhibit both Fermi liquid and non-Fermi liquid behavior, depending on their symmetry. Using an auxiliary boson method, we p

A. Sacuto, R. Combescot, N. Bontemps, C. A. Müller

Electronic Raman scattering measurements have been performed on $HgBa_{2}Ca_{2}Cu_{3}O_{8+δ} $ single crystals in the superconducting state. Pure electronic Raman spectra with no phonon structures hindering the analysis of the electronic continuum have been obtained. As a consequence, the spectra in the pure $B_{1g} $ and $B_{2g} $ symmetries are directly an

Erik Koch, Olle Gunnarsson, Richard M. Martin

The doped Fullerides can be well described by a Hubbard model, which comprises the partly filled, threefold-degenerate t_1u orbital and the on-site Coulomb interaction U. The orbital degeneracy is known to shift the critical ratio U_c/W for the Mott-Hubbard transition towards larger values. This puts the half-filled alkali-doped Fullerides A_3 C_60 on the me

Pascal Lederer, C. M. Chaves

The Field Induced Spin Density Wave phases observed in quasi-one-dimensional conductors of the Bechgaard salts family under magnetic field exhibit both Spin Density Wave order and a Quantized Hall Effect, which may exhibit sign reversals. The original nature of the condensed phases is evidenced by the collective mode spectrum. Besides the Goldstone modes, a

Karin M. Rabe, Eric Cockayne

A method for the calculation of the temperature dependence of dielectric and piezoelectric responses, based on the use of a first-principles effective Hamiltonian, is described. Results are presented for the ferroelectric perovskite PbTiO3. While the method includes only the soft-mode contributions to the responses, it is argued to give a good description of

Ken'ichi Takano

We derive a non-linear sigma model (NLSM) generally representing antiferromagnetic Heisenberg spin chains with inhomogeneous spin magnitudes and inhomogeneous nearest-neighbor exchange constants arrayed in finite periods. Only a restriction is that the average of spin magnitudes on one sublattice is the same as that on the other sublattice. The NLSM gives th

Flavio Seno, Cristian Micheletti, Amos Maritan, Jayanth R. Banavar

We present and discuss a novel approach to the direct and inverse protein folding problem. The proposed strategy is based on a variational approach that allows the simultaneous extraction of amino acid interactions and the low-temperature free energy of sequences of amino acids. The knowledge-based technique is simple and straightforward to implement even fo

Peter Schmitteckert, Rodolfo A. Jalabert, Dietmar Weinmann, Jean-Louis Pichard

When a system of spinless fermions in a disordered mesoscopic ring becomes instable between the inhomogeneous configuration driven by the random potential (Anderson insulator) and the homogeneous one driven by repulsive interactions (Mott insulator), the persistent current can be enhanced by orders of magnitude. This is illustrated by a study of the change o

T. Wolenski, M. Grodzicki, J. Appel

Recent neutron scattering and nuclear magnetic resonance experiments have revealed that the low temperature phase of doped V_{2-y}O_3 is an itinerant antiferromagnet with a helical spin structure. We use a band structure calculation as the point of departure to show that these experiments are in agreement with mean field results for an Overhauser spin-densit

A. Thilagam

We respond to criticisms raised by K. Varga (cond-mat/9802262) and reaffirm that the results in our original paper obtained using a two-body analytical method remains valid within the framework of an effective excitonic composite model. The conceptual model of the excitonic systems as well as the numerical method based on variational functions utilized by Va

Mikhail V. Velikanov, Raymond Kapral

Spatially-distributed, nonequilibrium chemical systems described by a Markov chain model are considered. The evolution of such systems arises from a combination of local birth-death reactive events and random walks executed by the particles on a lattice. The parameter γ, the ratio of characteristic time scales of reaction and diffusion, is used to gauge the

Debabrata Biswas

The structure of the semiclassical trace formula can be used to construct a quasi-classical evolution operator whose spectrum has a one-to-one correspondence with the semiclassical quantum spectrum. We illustrate this for marginally unstable integrable and non-integrable billiards and demonstrate its utility by quantizing them using arbitrary non-periodic tr

Debabrata Biswas

A change in boundary conditions (BC) from uniform Dirichlet to non-identical BC on the edges of a triangular billiard often brings about a dramatic change in quantum spectral fluctuations. We provide a theory for this based on periodic orbits and show that non-identical BC on adjacent edges can lead to a quantum splitting of periodic orbit families which res

E. Vergini, D. A. Wisniacki

We study quantum localization phenomena in chaotic systems with a parameter. The parametric motion of energy levels proceeds without crossing any other and the defined avoided crossings quantify the interaction between states. We propose the elimination of avoided crossings as the natural mechanism to uncover localized structures. We describe an efficient me

Adam G. Riess, Peter Nugent, Alexei V. Filippenko, Robert P. Kirshner

We present an empirical method which measures the distance to a Type Ia supernova (SN Ia) with a precision of ~ 10% from a single night's data. This method measures the supernova's age and luminosity/light-curve parameter from a spectrum, and the extinction and distance from an apparent magnitude and color. We are able to verify the precision of this

L. Nicolaci da Costa, C. N. A. Willmer, P. S. Pellegrini, O. L. Chaves

We report redshifts, magnitudes and morphological classifications for 5369 galaxies with $m_B \leq 15.5$ and 57 galaxies fainter than this limit, in two regions covering a total of 1.70 steradians in the southern celestial hemisphere. The galaxy catalog is drawn primarily from the list of non-stellar objects identified in the Guide Star Catalog (Lasker et al

S. H. Lubow, G. I. Ogilvie

We analyze the linear, 3D response to tidal forcing of a disk that is thin and thermally stratified in the direction normal to the disk plane. We model the vertical disk structure locally as a polytrope which represents a disk of high optical depth. We solve the 3D gas-dynamic equations semi-analytically in the neighborhood of a Lindblad resonance. These sol

I. Baraffe, Y. Alibert, D. Mera, G. Chabrier

We have computed stellar evolutionary models for stars in a mass range characteristic of Cepheid variables ($3<m/\Msol<12$) for different metallicities representative of the Galaxy and the Magellanic Clouds populations. The stellar evolution calculations are coupled to a linear non adiabatic stability analysis to get self-consistent mass-period-luminosity re

M. Dominik

To determine the magnification of an extended source caused by gravitational lensing one has to perform a two-dimensional integral over point-source magnifications in general. Since the point-source magnification jumps to an infinite value on caustics, special care is required. For a uniformly bright source, it has been shown earlier that the calculation sim

Denise Hurley-Keller, Mario Mateo, James Nemec

We have analyzed deep B and V photometry of the Carina dwarf spheroidal reaching below the old main-sequence turnoff to about V = 25. Using simulated color-magnitude diagrams to model a range of star formation scenarios, we have extracted a detailed, global star formation history. Carina experienced three significant episodes of star formation at about 15 Gy

R. Valdarnini, T. Kahniashvili, B. Novosyadlyj

We study linear power spectra and formation of large scale structures in flat cosmological models with $Λ\ge 0$ and cold plus hot dark matter components (MLM). The hot component consists of massive neutrinos with cosmological density $Ω_H$. The linearized Einstein-Boltzmann equations for the evolution of the metric and density perturbations are integrated fo

T. Belloni, G. Tagliaferri

We present the results of soft X-ray observations of the intermediate-age open cluster IC 4651 performed with the ROSAT PSPC. We detected 25 sources. Two are identified with a giant binary and a blue straggler respectively, both belonging to the cluster, and two with probable main-sequence members. Two other cases have ambiguous identification. Of the five b

P. M. Gondhalekar, L. E. B. Johansson, N. Brosch, I. S. Glass

$^{12}CO(J=1 \to 0)$ observations of 34 blue compact and star burst galaxies are presented. Although these galaxies are experiencing vigorous star formation at the current epoch, CO has been detected in only five of them. The five detections reported in this paper are all in galaxies with relatively red colours, (B-V)_0 > 0.4. The new observations, when comb

Yuichi Terashima, Hideyo Kunieda, Kazutami Misaki, Richard F. Mushotzky

We present the results of an ASCA observation of the LINER NGC 4579. A point-like X-ray source is detected at the nucleus with a 2-10 keV luminosity of 1.5x10^41 ergs/s assuming a distance of 16.8 Mpc. The X-ray spectrum is represented by a combination of a power-law with a photon index of ~1.7 and soft thermal component with kT~0.9 keV. An iron K emission l

Steen Hannestad

We investigate different types of neutrino hot dark matter with respect to structure formation and anisotropies in the cosmic microwave background radiation (CMBR). The possibility of neutrino hot dark matter produced through the decay of a heavier neutrino by the process nu_H -> nu_L + phi, where phi is a scalar particle, is discussed in detail. This type o

P. A. Woudt, R. C. Kraan-Korteweg, A. P. Fairall, H. Bohringer

ACO 3627 is a rich, nearby cluster of galaxies at the core of the Great Attractor. At the low galactic latitude of b = -7.2 the galactic extinction is significant. Nevertheless, its proximity makes it a prime target for studies of environmental effects on its cluster members. Here, we report on a multi-wavelength study of a Seyfert 1 galaxy at 30 arcminutes

M. Kapranov

The A-hypergeometric system studied by I.M. Gelfand, M.I. Graev, A.V. Zelevinsky and the author, is defined for a set A of characters of an algebraic torus. In this paper we propose a generalization of the theory where the torus is replaced by an arbitrary reductive group H and A is a set of irreducible representations of H. The functions are thus defined on

Guang-jiong Ni

Why does the $i=\sqrt{-1}$ appear essentially in the quantum mechanics? Why are there operators and noncommutativity (the uncertainty relation) in the quantum mechanics? Why are these two aspects closely related and indivisible? In probing these problems, a new point of view is proposed tentatively.

Ralf D. Tscheuschner

This paper is a lab tutorial (and a theory primer) for the integral quantum Hall effect experiment as conducted at Applied Solid State Physics, University of Bochum, Germany.

Sayan Kar

Solutions to the equations of motion of the low energy, effective field theory emerging out of compactified heterotic string theory are constructed by making use of the well-known duality symmetries. Beginning with four-dimensional solutions of the Einstein-massless scalar field theory in the canonical frame we first rewrite the corresponding solutions in th

The NOMAD Collaboration, J. Altegoer et al

A search was made for a new light gauge boson $X$ which might be produced in $π^{0}\toγ+ X$ decay from neutral pions generated by 450-GeV protons in the CERN SPS neutrino target. The X&#39;s would penetrate the downstream shielding and be observed in the NOMAD detector via the Primakoff effect, in the process of $X \toπ^{0}$ conversion in the external Coulom

Piotr Jaranowski, Andrzej Królak, Bernard F. Schutz

We present a theoretical background for the data analysis of the gravitational-wave signals from spinning neutron stars for Earth-based laser interferometric detectors. We introduce a detailed model of the signal including both the frequency and the amplitude modulations. We include the effects of the intrinsic frequency changes and the modulation of the fre

Pedro F. Gonzalez-Diaz

The metric describing a given finite sector of a four-dimensional asymptotically anti-de Sitter wormhole can be transformed into the metric of the time constant sections of a Tangherlini black hole in a five-dimensional anti-de Sitter spacetime when one allows light cones to tip over on the hypersurfaces according to the conservation laws of an one-kink. The

Radu P. Mondescu, M. Muthukumar

We have calculated the probability distribution function G(R,L|R&#39;,0) of the end-to-end vector R-R&#39; and the mean-square end-to-end distance (R-R&#39;)^2 of a Gaussian polymer chain embedded on a sphere S^(D-1) in D dimensions and on a cylinder, a cone and a curved torus in 3-D. We showed that: surface curvature induces a geometrical localization area;

L. Bergstrom, J. Edsjo, P. Ullio

We investigate if the gamma ray halo, for which recent evidence has been found in EGRET data, can be explained by neutralino annihilations in a clumpy halo. We find that the measured excess gamma ray flux can be explained through a moderate amount of clumping in the halo. Moreover, the required amount of clumping implies also a measureable excess of antiprot

Raul Jimenez, Paolo Padoan, Francesca Matteucci, Alan Heavens

We investigate in detail the hypothesis that low surface brightness galaxies (LSB) differ from ordinary galaxies simply because they form in halos with large spin parameters. We compute star formation rates using the Schmidt law, assuming the same gas infall dependence on surface density as used in models of the Milky Way. We build stellar population models,

Francoise Combes

In the interstellar medium, as well as in the Universe, large density fluctuations are observed, that obey power-law density distributions and correlation functions. These structures are hierarchical, chaotic, turbulent, but are also self-organizing. The apparent disorder is not random noise, but can be described by a fractal, with a deterministic fractal di

Jesper Lykke Jacobsen, Jane&#39; Kondev

Exact results for conformational statistics of compact polymers are derived from the two-flavour fully packed loop model on the square lattice. This loop model exhibits a two-dimensional manifold of critical fixed points each one characterised by an infinite set of geometrical scaling dimensions. We calculate these dimensions exactly by mapping the loop mode

Weixue Li, Tzuchiang Wang

On the basis of the pseudopotential plane-wave(PP-PW) method in combination with the local-density-functional theory(LDFT), complete stress-strain curves for the uniaxial loading and uniaxial deformation along the [001] and [111] directions, and the biaxial proportional extension along [010] and [001] of aluminium are obtained. During the uniaxial loading, c

Michael K. -H. Kiessling, Herbert Spohn

The distribution of eigenvalues of N times N random matrices in the limit N to infinity is the solution to a variational principle that determines the ground state energy of a confined fluid of classical unit charges. This fact is a consequence of a more general theorem, proven here, in the statistical mechanics of unstable interactions. Our result establish

Wolfgang Mueck, K. S. Viswanathan

We use the correspondence between scalar field theory on $AdS_{d+1}$ and a conformal field theory on $R^d$ to calculate the 3- and 4-point functions of the latter. The classical scalar field theory action is evaluated at tree level.

Alejandro Ayala, Juan Carlos D&#39;Olivo, Manuel Torres

For neutrinos with a magnetic moment, we show that the collisions in a hot and dense plasma act as an efficient mechanism for the conversion of $ν_L$ into $ν_R$. The production rate for right-handed neutrinos is computed in terms of a resummed photon propagator which consistently incorporates the background effects. Assuming that the entire energy in a super

Alberto Guijosa

With the aim of clarifying the eleven dimensional content of Matrix theory, we examine the dependence of a theory in the infinite momentum frame (IMF) on the (purely spatial) longitudinal compactification radius R. It is shown that in a point particle theory the generic scattering amplitude becomes independent of R in the IMF. Processes with zero longitudina

J. Richard Bond, Dmitri Pogosyan, Tarun Souradeep

The measurements of CMB anisotropy have opened up a window for probing the global topology of the universe on length scales comparable to and beyond the Hubble radius. For compact topologies, the two main effects on the CMB are: (1) the breaking of statistical isotropy in characteristic patterns determined by the photon geodesic structure of the manifold and

Indranil DasGupta, Ricardo Rademacher, Peter Suranyi

Using a simple numerical method, we compute the stability of the MSSM vacuum with respect to tunneling. The stability criterion is then used to put restrictions on the mass parameters. These restrictions are necessary conditions for the vacuum stability and compliment the existing sufficiency conditions obtained analytically.

Marcos Marino, Frederic Zamora

We study the soft breaking of N=2 self-dual gauge theories down to N=0 by promoting the coupling constant and hypermultiplet masses to spurions, and we analyze the microscopic duality symmetry in the resulting models. Explicit formulae are given for the Seiberg-Witten periods and couplings in the case of SU(2), and we perform a numerical study of the non-sup

Tohru Eguchi

We analyze the strong coupling behavior of the large N gauge theories in 4-dimensions with N=4 supersymmetry by making use of S-duality. We show that at large values of the coupling constant $λ=g_{YM}^2N$ the j-th non-planar amplitude $f_j(λ) (j=0,1,2 ...)$ behaves as $f_j(λ)\approx λ^j$. Implication of this behavior is discussed in connection with the super

M. Reuter

A hidden gauge theory structure of quantum mechanics which is invisible in its conventional formulation is uncovered. Quantum mechanics is shown to be equivalent to a certain Yang-Mills theory with an infinite-dimensional gauge group and a nondynamical connection. It is defined over an arbitrary symplectic manifold which constitutes the phase-space of the sy

A. A. Babich, A. A. Pankov, N. Paver

In the case of the process $e^+e^-\toμ^+μ^-$, we study the sensitivity to either $Z^\prime$ or anomalous gauge coupling effects of two new observables, $σ_+$ and $σ_-$, conveniently defined for such kind of analysis. We discuss general properties of the deviations of these observables from the Standard Model predictions, and derive the model-independent boun

Manuel Drees

This write--up gives a rather elementary introduction into particle physics aspects of the cosmological Dark Matter puzzle. A fairly comprehensive list of possible candidates is given; in each case the production mechanism and possible ways to detect them (if any) are described. I then describe detection of the in my view most promising candidates, weakly in

T. Han, T. Yanagida, R. -J. Zhang

We consider states in the adjoint representation of the Standard Model gauge group as messengers for mediation of supersymmetry (SUSY) breaking. These new messengers can shift the gauge coupling unification to the string scale at O(5x10^{17} GeV) if their masses are at O(10^{14} GeV). The predicted SUSY mass spectrum at the electroweak scale is significantly

PHENIX Collaboration, David P. Morrison

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.

Yu. E. Lozovik, A. M. Ruvinsky

The transport relaxation time $τ(P)$ and the mean free path of magnetoexcitons in single and coupled quantum wells are calculated ($P$ is the magnetic momentum of the magnetoexciton). We present the results for magnetoexciton scattering in a random field due to (i) quantum well width fluctuations, (ii) composite fluctuations and (iii) ionized impurities. The

R. Kotecky, D. Ueltschi

Quantum lattice systems are rigorously studied at low temperatures. When the Hamiltonian of the system consists of a potential (diagonal) term and a - small - off-diagonal matrix containing typically quantum effects, such as a hopping matrix, we show that the latter creates an effective interaction between the particles. In the case that the potential matrix

D. Sornette

Some problems with the recent stimulating proposal of a ``Gauge Theory of Finance&#39;&#39; by Ilinski and collaborators are outlined. First, the derivation of the log-normal distribution is shown equivalent both in information and mathematical content to the simpler and well-known derivation, dating back from Bachelier and Samuelson. Similarly, the re-deriv

Mikael Sahrling

We consider magnetic field evolution of neutron stars during polar-cap accretion. The size of the polar cap increases as the field decays, and is set by the last open field line before the accretion disk. Below the polar cap we find the temperature to be so high that electron-phonon scattering dominates the resistivity. Outside the polar cap region, the temp

A. Barrau, R. Bazer-Bachi, E. Beyer, H. Cabot

The CAT (Cherenkov Array at Themis) imaging telescope, equipped with a very-high-definition camera (546 fast phototubes with 0.12 degrees spacing surrounded by 54 larger tubes in two guard rings) started operation in Autumn 1996 on the site of the former solar plant Themis (France). Using the atmospheric Cherenkov technique, it detects and identifies very hi

Shude Mao, Hans J. Witt

Extended source size effects have been detected in photometric monitoring of gravitational microlensing events. We study similar effects in the centroid motion of an extended source lensed by a point mass. We show that the centroid motion of a source with uniform surface brightness can be obtained analytically. For a source with circularly symmetric limb-dar

Andrzej A. Zdziarski

We solve for the structure of a hot accretion disc with unsaturated thermal Comptonisation of soft photons and with advection, generalizing the classical model of Shapiro et al. The upper limit on the accretion rate due to advection constrains the luminosity to $\simless 0.15 y^{3/5} α^{7/5}$ of the Eddington limit, where $y$ and $α$ are the Compton and visc

Telescope Array Collaboration

We will report the observations of TeV gamma ray flares from Markarian 501 using Telescope Array Prototype. The observation were carried out continuously from the end of March to the end of July in 1997. The energy spectrum, and the time variation of the gamma ray intensities are shown. The intensity has been changed by the order of magnitude in this period

Tarun Souradeep, Dmitry Pogosyan, J. Richard Bond

The measurements of CMB anisotropy have opened up a window for probing the global topology of the universe on length scales comparable to and beyond the Hubble radius. We have developed a new method for calculating the CMB anisotropy in models with nontrivial topology and apply it to open universe models with compact spatial topology. We conduct a Bayesian p

A. H. Hoang, M. C. Smith, T. Stelzer, S. Willenbrock

The pole mass of a heavy quark is ambiguous by an amount of order $Λ_{QCD}$. We show that the heavy-quark potential, $V(r)$, is similarly ambiguous, but that the total static energy, $2M_{pole}+V(r)$, is unambiguous when expressed in terms of a short-distance mass. This implies that the extraction of a short-distance mass from the quarkonium spectrum is free

Harold Widom

For the unitary ensembles of $N\times N$ Hermitian matrices associated with a weight function $w$ there is a kernel, expressible in terms of the polynomials orthogonal with respect to the weight function, which plays an important role. For the orthogonal and symplectic ensembles of Hermitian matrices there are $2\times2$ matrix kernels, usually constructed u

D. A. Garanin

The self-consistent Gaussian approximation (SCGA) for classical spin systems described by a completely anisotropic D-component vector model is proposed, which takes into account fluctuations of the molecular field and thus is a next step beyond the molecular field approximation. The SCGA is sensitive to the lattice dimension and structure and to the form of

S. Nojiri, S. D. Odintsov

We calculate the one-loop effective action for conformal matter (scalars, spinors and vectors) on spherically symmetric background. Such effective action (in large $N$ approximation and expansion on curvature) is used to study quantum aspects of Schwarzschild-de Sitter black holes (SdS BHs) in nearly degenerated limit (Nariai BH). We show that for all types

Ariel Caticha

Quantum theory is formulated as the only consistent way to manipulate probability amplitudes. The crucial ingredient is a consistency constraint: if there are two different ways to compute an amplitude the two answers must agree. This constraint is expressed in the form of functional equations the solution of which leads to the usual sum and product rules fo

D. A. Garanin

The corrections to the Curie temperature T_c of a ferromagnetic film consisting of N layers are calculated for N \gg 1 for the model of D-component classical spin vectors in the limit D \to \infty, which is exactly soluble and close to the spherical model. The present approach accounts, however, for the magnetic anisotropy playing the crucial role in the cro

Uffe Hellsten, Nickolay Y. Gnedin, Jordi Miralda-Escude

We use numerical simulations of structure formation in a Cold Dark Matter model to predict the absorption lines in the soft X-rays produced by heavy elements in the shock-heated intergalactic medium at low redshift. The simulation incorporates a model for metal production in galaxies and the subsequent dispersion of the metals to the intergalactic medium. We

Christophe Baudet, Olivier Michel, William J. Williams

We describe here an experimental technique based on the acoustic scattering phenomenon allowing the direct probing of the vorticity field in a turbulent flow. Using time-frequency distributions, recently introduced in signal analysis theory, for the analysis of the scattered acoustic signals, we show how the legibility of these signals is significantly impro

L. V. Bravina, M. I. Gorenstein, M. Belkacem, S. A. Bass

Local kinetic and chemical equilibration is studied for Au+Au collisions at 10.7 AGeV in the microscopic Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). The UrQMD model exhibits dramatic deviations from equilibrium during the high density phase of the collision. Thermal and chemical equilibration of the hadronic matter seems to be established in

Colin S. Rosenthal

I present a matched-wave asymptotic analysis of the driving of solar oscillations by a general localised source. The analysis provides a simple mathematical description of the asymmetric peaks in the power spectrum in terms of the relative locations of eigenmodes and troughs in the spectral response. It is suggested that the difference in measured phase func

L. Cappiello, R. Marotta, R. Pettorino, F. Pezzella

We give a simple prescription for computing, in the framework of the bosonic string theory, off-shell one-loop amplitudes with any number of external massless particles, both for the open and for the closed string. We discuss their properties and, in particular, for the two-string one-loop amplitudes we show their being transverse.

B. Jackson, J. F. McCann, C. S. Adams

We solve the Gross-Pitaevskii equation to model the behaviour of a weakly-interacting Bose condensate. Solutions are presented for the eigenstates in one- and two-dimensional harmonic traps. We include the effect of gravity and coupling to a second condensate to simulate an output coupler for Bose condensed atoms, and find that the output pulse shape is in q

Roberto Emparan

We present and analyze solutions of D=11 supergravity describing the ``near-horizon&#39;&#39; (i.e., asymptotically AdS_4 x S^7) geometry of M2-branes wrapped on surfaces of arbitrary genus. We study the forces experienced by test M2-branes in such backgrounds, and find evidence that extremal branes on surfaces of genera higher than the torus are unstable. U