February 2000 arXiv papers — page 17

Oleg Lebedev, Will Loinaz, Tatsu Takeuchi

We study constraints on type-II two Higgs doublet models at large tan{beta} from LEP/SLD Z-pole data and from lepton universality violation in W decay. We perform a global fit and find that, in the context of Z decay, the LEP/SLD experimental values for lepton universality violation, R_b, and A_b all somewhat disfavor the model. Contributions from the neutra

Adam Lewandowski

We examine constraints on a model with pure right-handed third generation charged couplings. The parameters of the right-handed mixing matrix and the right-handed coupling strength are constrained from semi-leptonic B decays, the mass difference of neutral mesons, the CP violating observables epsilon and epsilon', and the electric dipole moment of the ne

S. Moretti

We study the decays into six quarks of off-shell pairs of W bosons produced in electron-positron annihilations, through the O(as^2) order in the strong coupling constant. We give explicit helicity amplitude formulae. We present numerical results in the context of phenomenological analyses of relevance at LEP2 and future Linear Colliders: such as MW determina

R. Fiore, L. L. Jenkovszky, A. Lengyel, F. Paccanoni

A model for the Pomeron at t=0 is suggested. It is based on the idea of a finite sum of ladder diagrams in QCD. Accordingly, the number of s-channel gluon rungs and correspondingly the powers of logarithms in the forward scattering amplitude depends on the phase space (energy) available, i.e. as energy increases, progressively new prongs with additional gluo

M. Consoli

The basic idea that gravity can be a long-wavelength effect {\it induced} by the peculiar ground state of an underlying quantum field theory leads to consider the implications of spontaneous symmetry breaking through an elementary scalar field. We point out that Bose-Einstein condensation implies the existence of long-range order and of a gap-less mode of th

V. N. Baier, V. M. Katkov

The creation of electron-positron pair by a photon and the bremsstrahlung of an electron in a medium are considered in high-energy region, where influence of the multiple scattering on the processes (the Landau-Pomeranchuk-Migdal (LPM) effect) becomes essential. The pair photoproduction probability is calculated with an accuracy up to the "next to leadin

Shin Ishida, Muneyuki Ishida, Tomohito Maeda

Assuming the spin-independence for confining force, we give a covariant quark representation of general composite meson systems with definite Lorentz transformation properties. For benefit of this representation we are able to deduce automatically the transformation rules of composite mesons for general symmetry operations from those of constituent (exciton)

D0 Collaboration, B. Abbott

We report on a search for supersymmetry using the DØdetector. The 1994-1996 data sample of $\sqrt{s}=1.8$ TeV $p\bar{p}$ collisions was analyzed for events containing two leptons ($e$ or $μ$), two or more jets, and missing transverse energy. Assuming the minimal supergravity model, with $A_0=0$ and $μ<0$, various thresholds were employed to optimize the sear

A. Asratyan, M. Balatz, D. Boehnlein, S. Childres

Novel detector schemes are proposed for the short-baseline neutrino experiments of next generation, aimed at exploring the large-$Δm^2$ domain of \omutau oscillations in the appearance mode. These schemes emphasize good spectrometry for charged particles and for electromagnetic showers and efficient reconstruction of \ypi_gg decays. The basic elements are a

Toshinao Akuzawa, Noboru Murata

We construct new algorithms from scratch, which use the fourth order cumulant of stochastic variables for the cost function. The multiplicative updating rule here constructed is natural from the homogeneous nature of the Lie group and has numerous merits for the rigorous treatment of the dynamics. As one consequence, the second order convergence is shown. Fo

A. Klümper, D. C. Johnston

We present a new application of the traditional thermodynamic Bethe ansatz to the spin-1/2 antiferromagnetic uniform Heisenberg chain and derive exact nonlinear integral equations for just {\em two} functions describing the elementary excitations. Using this approach the magnetic susceptibility $χ$ and specific heat C versus temperature T are calculated to h

P. W. Brouwer, X. Waintal, B. I. Halperin

In the presence of spin-orbit scattering, the splitting of an energy level in a generic small metal grain due to the Zeeman coupling to a magnetic field B depends on the direction of B, as a result of mesoscopic fluctuations. The anisotropy is described by the eigenvalues g_j^2 (j=1,2,3) of a tensor G, corresponding to the (squares of) g-factors along three

Raul Donangelo, Alex Hansen, Kim Sneppen, Sergio R. Souza

We propose a simple market model where agents trade different types of products with each other by using money, relying only on local information. Value fluctuations of single products, combined with the condition of maximum profit in transactions, readily lead to persistent fluctuations in the wealth of individual agents.

Oleg Derzhko, Johannes Richter, Oles&#39; Zaburannyi

Using the Jordan-Wigner transformation and the continued-fraction method we calculate exactly the density of states and thermodynamic quantities of the periodic nonuniform spin-1/2 isotropic XY chain in a transverse field. We discuss in detail the changes in the behaviour of the thermodynamic quantities caused by regular nonuniformity. The exact consideratio

E. Bascones, C. P. Herrero, F. Guinea, G. Schon

The role of non-equilibrium effects in the conductance through quantum dots is investigated. Associated with single-electron tunneling are shake-up processes and the formation of excitonic-like resonances. They change qualitatively the low temperature properties of the system. We analyze by quantum Monte Carlo methods the renormalization of the effective cap

C. Bauer, T. Bieker, S. Dietrich

Using a density functional based interface displacement model we determine the effective interaction potential between two spherical particles which are immersed in a homogeneous fluid such as the vapor phase of a one-component substance or the A-rich liquid phase of a binary liquid mixture composed of A and B particles. If this solvent is thermodynamically

D. Panja, J. R. Dorfman, Henk van Beijeren

We study the Lyapunov exponents for a moving, charged particle in a two-dimensional Lorentz gas with randomly placed, non-overlapping hard disk scatterers placed in a thermostatted electric field, $\vec{E}$. The low density values of the Lyapunov exponents have been calculated with the use of an extended Lorentz-Boltzmann equation. In this paper we develop a

Hemant Bokil, Barbara Drossel, Mike Moore

We have argued in recent papers that Monte Carlo results for the equilibrium properties of the Edwards-Anderson spin glass in three dimensions, which had been interpreted earlier as providing evidence for replica symmetry breaking, can be explained quite simply within the droplet model once finite size effects and proximity to the critical point are taken in

Yoshiyuki Kabashima, Tatsuto Murayama, David Saad

The relation between Ising spin systems and public-key cryptography is investigated using methods of statistical physics. The insight gained from the analysis is used for devising a matrix-based cryptosystem whereby the ciphertext comprises products of the original message bits; these are selected by employing two predetermined randomly-constructed sparse ma

Marc Mezard, Giorgio Parisi

This paper gives an introduction and brief overview of some of our recent work on the equilibrium thermodynamics of glasses. We have focused onto first principle computations in simple fragile glasses, starting from the two body interatomic potential. A replica formulation translates this problem into that of a gas of interacting molecules, each molecule bei

Peter Scheidler, Walter Kob, Kurt Binder

We present the results of a Molecular Dynamics computer simulation of a binary Lennard-Jones liquid confined in a narrow pore. The surface of the pore has an amorphous structure similar to that of the confined liquid. We find that the static properties of the liquid are not affected by the confinement, while the dynamics changes dramatically. By investigatin

Ayjamal Abdurahman, Alok Shukla, Michael Dolg

Correlated {\em ab initio} electronic structure calculations are reported for the polymers lithium hydride chain $[LiH]_{\infty}$ and beryllium hydride $[Be_{2}H_{4}]_{\infty}$. First, employing a Wannier-function-based approach, the systems are studied at the Hartree-Fock level, by considering chains simulating the infinite polymers. Subsequently, for the m

Charles Reichhardt, Cynthia J. Olson, Niels Gronbech-Jensen

We examine vortex dynamics and pinning in layered superconductors using three-dimensional molecular dyanmics simulations of magnetically interacting pancake vortices. Our model treats the magnetic interactions of the pancakes exactly, with longe-range logarithmic interactions both within and between planes. At the matching field the vortices are aligned with

Ar. Abanov, Andrey V. Chubukov

We consider spin and electronic properties of itinerant electron systems, described by the spin-fermion model, near the antiferromagnetic critical point. We expand in the inverse number of hot spots in the Brillouin zone, N and present the results beyond previously studied $N = \infty $ limit. We found two new effects: (i) Fermi surface becomes nested at hot

B. G. Piner, P. G. Edwards, A. E. Wehrle, H. Hirabayashi

We present the first VLBI Space Observatory Programme (VSOP) observations of the gamma-ray blazar 3C 279 at 1.6 and 5 GHz. The combination of the VSOP and VLBA-only images at these two frequencies maps the jet structure on scales from 1 to 100 mas. On small angular scales the structure is dominated by the quasar core and the bright secondary component `C4&#3

Rita M. Sambruna

We present exactly simultaneous X-ray and TeV monitoring with {\it RXTE} and HEGRA of the TeV blazar Mrk 501 during 15 days in 1998 June. After an initial period of very low flux at both wavelengths, the source underwent a remarkable flare in the TeV and X-ray energy bands, lasting for about six days and with a larger amplitude at TeV energies than in the X-

James S. Bullock, Andrey V. Kravtsov, David H. Weinberg

One of the main challenges facing standard hierarchical structure formation models is that the predicted abundance of galactic subhalos with circular velocities of 10-30 km/s is an order of magnitude higher than the number of satellites actually observed within the Local Group. Using a simple model for the formation and evolution of dark halos, based on the

Bing Zhang, Rosemary F. G. Wyse

We investigate a model of disk galaxies whereby viscous evolution of the gaseous disk drives material inwards to form a proto-bulge. We start from the standard picture of disk formation through the settling of gas into a dark halo potential well, with the disk initially coming into centrifugal equilibrium with detailed conservation of angular momentum. We de

Nir J. Shaviv

We analyze the wind generated by the great 20 year long super-Eddington outburst of eta-Carinae. We show that using classical stellar atmospheres and winds theory, it is impossible to construct a consistent wind model in which a sufficiently small amount of mass, like the one observed, is shed. One expects the super-Eddington luminosity to drive a thick wind

L. Binette, V. Luridiana

We quantify the energy radiated through all the collisionally excited lines in a photoionized nebula which is permeated by temperature fluctuations. We assume that these correspond to hot spots which are the results of an unknown heating process distinct from the photoelectric heating. We consider all the effects of using a higher mean temperature (as compar

L. Binette, J. D. Kurk, M. Villar-Martin, H. J. A. Rottgering

Observations are presented showing the doublet CIV 1550 absorption lines superimposed on the CIV emission in the radio galaxy 0943-242. Within the errors, the redshift of the absorption system that has a column density of N_CIV = 10^{14.5 +- 0.1} cm-2 coincides with that of the deep Ly-alpha absorption trough observed by Rottgering et al. (1995). The gas see

D. Cesarsky, J. Lequeux, C. Ryter, M. Gerin

We present spectrophotometric imaging mid-IR observations of the reflection nebula Ced201. Ced201 is a part of a molecular cloud illuminated by a B9.5V star moving through it at more than 12 km/s. The spectra of Ced201 give evidence for transformation of very small carbonaceous grains into the carriers of the Aromatic Infrared Bands (AIBs), due to the radiat

Etienne Parizot, Luke Drury

We show that the available constraints relating to $^{6}$LiBeB Galactic evolution can be accounted for by the so-called superbubble model, according to which particles are efficiently accelerated inside superbubbles out of a mixture of supernova ejecta and ambient interstellar medium. The corresponding energy spectrum is required to be flat at low energy (in

M. Tavani, D. Band, G. Ghirlanda

We present the main results of a study of time-resolved spectra of 43 intense GRBs detected by BATSE. We considered the 4-parameter Band model and the Optically Thin Synchrotron Shock model (OTSSM). We find that the large majority of time-resolved spectra of GRBs are in remarkable agreement with the OTSSM. However, about 15 % of initial GRB pulses show an ap

A. Rosenberg, G. Piotto, I. Saviane, A. Aparicio

We present the first part of the first large and homogeneous CCD color-magnitude diagram (CMD) data base, comprising 52 nearby Galactic globular clusters (GGC) imaged in the V and I bands using only two telescopes (one for each hemisphere). The observed clusters represent 75% of the known Galactic globulars with (m-M)v<=16.15 mag, cover most of the globular

Sidney Bludman

For a universe presently dominated by static or dynamic vacuum energy, cosmological constant (LCDM) or quintessence (QCDM), we calculate the asymptotic collapsed mass fraction as function of the present ratio of vacuum energy to clustered mass, Ω_{Q0}/Ω_{m0}. Identifying these collapsed fractions as anthropic probabilities, we find the value Ω_{Q0}/Ω_{m0} \s

James M. Lattimer, Madappa Prakash

The equation of state (EOS) of dense matter plays an important role in the supernova phenomenon, the structure of neutron stars, and in the mergers of compact objects (neutron stars and black holes). During the collapse phase of a supernova, the EOS at subnuclear densities controls the collapse rate, the amount of deleptonization and thus the size of the col

Matthew R. Bate

We review recent advances in the study of binary star formation that have been made using the smoothed particle hydrodynamics (SPH) technique. We discuss the importance of ensuring that the Jeans mass is always resolved during a self-gravitating SPH calculation. Even obeying this criterion, we show that it is now possible to perform calculations which follow

R. M. Sambruna, G. Chartas, M. Eracleous, R. Mushotzky

We report the detection with Chandra of a Low-Luminosity AGN (LLAGN) in the Low Ionization Emission Line Region (LINER) hosted by Hydra A, a nearby (z=0.0537) powerful FRI radio galaxy with complex radio and optical morphology. In a 20 ks ACIS-S exposure during the calibration phase of the instrument, a point source is detected at energies $\grtsim$ 2 keV at

D. M. Alexander, H. Aussel

We present new techniques to produce IRAS 12 micron samples of galaxies and stars. We show that previous IRAS 12 micron samples are incompatible for detailed comparison with ISO surveys and review their problems. We provide a stellar infrared diagnostic diagram to distinguish galaxies from stars without using longer wavelength IRAS colour criteria and produc

Craig J. Copi, Glenn D. Starkman

One of the challenges of X-ray astronomy is how to both collect large numbers of photons yet attain high angular resolution. Because X-ray telescopes utilize grazing optics, to collect more photons requires a larger acceptance angle which in turn compromises the angular resolution. All X-ray telescopes thus have angular resolution far poorer than their diffr

S. Moehler, U. Heber, R. Napiwotzki, D. Koester

We present the first spectra obtained with the Very Large Telescope for white dwarfs in a globular cluster. Estimates of atmospheric parameters are obtained and compared to evolutionary tracks. We discuss possible implications for the distance scale of globular clusters and white dwarf evolution and demonstrate how white dwarfs might be used to establish an

Katsuaki Asano, Takeshi Fukuyama

We study semianalytically the gravitational effects on neutrino pair annihilation near the neutrinosphere and around the thin accretion disk. For the disk case, we assume that the accretion disk is isothermal and that the gravitational field is dominated by the Schwarzschild black hole. General relativistic effects are studied only near the rotation axis. Th

E. Sturm, D. Lutz, D. Tran, H. Feuchtgruber

We present an inventory of mid-infrared spectral features detected in high resolution 2.4 to 45um ISO-SWS spectra of the galaxies M82, NGC253, Circinus, NGC1068, and the 30Doradus region of the LMC. We discuss their identifications and highlight possible relations between these features and the physical state of the interstellar medium in galaxies. In the 5-

Y. E. Lyubarskii, S. A. Petrova

We consider resonant inverse Compton scattering of thermal photons by secondary particles above the pulsar polar gap. The process appears to be an essential energy loss mechanism for the particles. The distribution function of the secondary plasma particles is found to be strongly affected by the scattering. It becomes two-humped implying the development of

Jihn E. Kim

It is emphasized that the existence of a very light axion is consistent with the strong CP invariance and cosmological and astrophysical constraints. The attempt to embed the very light axion in superstring models is discussed.

J. -P. Macquart, L. Kedziora-Chudczer, D. P. Rayner, D. L. Jauncey

We report strong variability in the circular and linear polarization of the intraday variable source PKS 1519-273. The circular polarization varies on a timescale of hours to days at frequencies between 1.4 and 8.6 GHz, and is strongly correlated with variations in the total intensity at 4.8 and 8.6 GHz. We argue that the variability is due to interstellar s

K. O&#39;Neil, M. A. W. Verheijen, S. S. McGaugh

We present VLA H I observations of the low surface brightness galaxy UGC 12695 and its two companions, UGC 12687 and a newly discovered dwarf galaxy 2333+1234. UGC 12695 shows solid body rotation but has a very lopsided morphology of the H I disk, with the majority of the H I lying in the southern arm of the galaxy. The H I column density distribution of thi

D. Blaschke, G. Burau, Yu. L. Kalinovsky, P. Maris

Finite temperature spatial $\bar q q$ correlation modes in the $π$ and $ρ$ channels are studied with the rainbow-ladder truncated quark Dyson-Schwinger equation and Bethe-Salpeter equation in the Matsubara formalism. To retain the finite range of the effective interaction while facilitating summation over fermion Matsubara modes necessary to ensure continuit

W. Fischler, Joaquim Gomis, E. Gorbatov, A. Kashani-Poor

We study noncommutative field theories at finite temperature to learn more about the degrees of freedom in the non-planar sector of these systems. We find evidence for winding states. At temperatures for which the thermal wavelength is smaller than the noncommutativity scale, there is a drastic reduction of the degrees of freedom in the non-planar sector. In

Vladislav S. Olkhovsky, Erasmo Recami, Giovanni Salesi

We study the phenomenon of one-dimensional non-resonant tunnelling through two successive potential barriers, separated by an intermediate free region R, by analyzing the relevant solutions to the Schroedinger equation. We find that the total traversal time is INDEPENDENT not only of the barrier widths (the so-called &#34;Hartman effect&#34;), but also of th

E. V. Gotthelf, Q. Daniel Wang

We present a high resolution Chandra X-ray observation of PSR B0540-69, the Crab-like 50 msec pulsar in the Large Magellanic Cloud. We use phase-resolved imaging to decompose the extended X-ray emission, as expected of a synchrotron nebula, from the point-like emission of the pulsar. The image of the pulsed X-ray emission shows a well-defined point-spread fu

E. De Sanctis, W. -D. Nowak, K. A. Oganessyan

We consider the single-spin azimuthal asymmetries recently measured at the HERMES experiment for charged pions produced in semi-inclusive deep inelastic scattering of leptons off longitudinally polarized protons. Guided by the experimental results and assuming a vanishing twist-2 transverse quark spin distribution in the longitudinally polarized nucleon, den

D. Anselmi, L. Girardello, M. Porrati, A. Zaffaroni

The holographic RG flow in AdS/CFT correspondence naturally defines a holographic scheme in which the central charge c and the beta function are related by a universal formula. We perform some checks of that formula and we compare it with quantum field theory expectations. We discuss alternative definitions of the c-function. In particular, we compare, for a

Neil D. Lambert, Ivo Sachs

We derive the action for the non-abelian field theory living on parallel non-BPS D3-branes in type IIA theory on the orbifold T^4/I_4(-1)^F_L. The classical moduli space for the massless scalars originating in the ``would be&#39;&#39; tachyonic sector shows an interesting structure. In particular, it contains non-abelian flat directions. At a generic point i

A. Grazian, S. Cristiani, V. D&#39;Odorico, A. Omizzolo

This paper presents the first results of a survey for bright quasars (V < 14.5 and R<15.4) covering the North Hemisphere at galactic latitudes |b|>30. The photometric database is derived from the GSC and USNO catalogs. Quasars are identified on the basis of their X-ray emission measured in the ROSAT All Sky Survey. The surface density of quasars brighter tha

Hanno Sahlmann, Rainer Verch

In the setting of vector-valued quantum fields obeying a linear wave-equation in a globally hyperbolic, stationary spacetime, it is shown that the two-point functions of passive quantum states (mixtures of ground- or KMS-states) fulfill the microlocal spectrum condition (which in the case of the canonically quantized scalar field is equivalent to saying that

F. Krüger, J. C. Romão

We study rare exclusive B decays based on the quark-level transition b->s(d)l^+l^-, where l=e or mu, in the context of supersymmetric theories with minimal flavour violation. We present analytic expressions for various mixing matrices in the presence of new CP-violating phases, and examine their impact on observables involving B and \bar{B} decays. An estima

V. E. Kravtsov, A. M. Tsvelik

It is shown that the parametric spectral statistics in the critical random matrix ensemble with multifractal eigenvector statistics are identical to the statistics of correlated 1D fermions at finite temperatures. For weak multifractality the effective temperature of fictitious 1D fermions is proportional to (1-d_{n})/n, where d_{n} is the fractal dimension

L. Coraggio, A. Covello, A. Gargano, N. Itaco

The structure of the N=50 isotones 98Cd, 97Ag, and 96Pd is studied in terms of shell model employing a realistic effective interaction derived from the Bonn-A nucleon-nucleon potential. The single-hole energies are fixed by resorting to an analysis of the low-energy spectra of the isotones with A>= 91. Comparison shows that our results are in very satisfacto

Alexander Schekochihin, Russell Kulsrud

Most of the theoretical results on the kinematic amplification of small-scale magnetic fluctuations by turbulence have been confined to the model of white-noise-like advecting turbulent velocity field. In this work, the statistics of the passive magnetic field in the diffusion-free regime are considered for the case when the advecting flow is finite-time cor

M. S. L. du Croo de Jongh, J. M. J. van Leeuwen, W. van Saarloos

We combine the Density Matrix Technique (DMRG) with Green Function Monte Carlo (GFMC) simulations. The DMRG is most successful in 1-dimensional systems and can only be extended to 2-dimensional systems for strips of limited width. GFMC is not restricted to low dimensions but is limited by the efficiency of the sampling. This limitation is crucial when the sy

S. A. Gurvitz

We study a one-dimensional Anderson model in which one site interacts with a detector monitoring the occupation of that site. We demonstrate that such an interaction, no matter how weak, leads to total delocalization of the Anderson model, and we discuss the experimental consequences

Tom Theuns, Saleem Zaroubi

The temperature of the intergalactic medium (IGM) is an important factor in determining the line-widths of the absorption lines in the Lyman-alpha forest. We present a method to characterise the line-widths distribution using a decomposition of a Lyman-alpha spectrum in terms of discrete wavelets. Such wavelets form an orthogonal basis so the decomposition i

Ryszard Horodecki, Michal Horodecki, Pawel Horodecki

We adopt the view according to which information is the primary physical entity that posseses objective meaning. Basing on two postulates that (i) entanglement is a form of quantum information corresponding to internal energy (ii) sending qubits corresponds to work, we show that in the closed bipartite quantum communication systems the information is conserv

Giovanni Felder, Boris Shoikhet

In the present paper we prove a statement closely related to the cyclic formality conjecture. In particular, we prove that for a divergence-free Poisson bivector field on R^d, the Kontsevich star-product with the harmonic angle function is cyclic. We also prove a globalization of this theorem in the case of arbitrary Poisson manifolds and prove a generalizat

Yan-Gang Miao, R. Manvelyan, H. J. W. Mueller-Kirsten

The self-duality of chiral p-forms was originally investigated by Pasti, Sorokin and Tonin in a manifestly Lorentz covariant action with non-polynomial auxiliary fields. The investigation was then extended to other chiral p-form actions. In this paper we point out that the self-duality appears in a wider context of theoretical models that relate to chiral p-

Yair Sigad, Enzo Branchini, Avishai Dekel

We present a simple method for evaluating the nonlinear biasing function of galaxies from a redshift survey. The nonlinear biasing is characterized by the conditional mean of the galaxy density fluctuation given the underlying mass density fluctuation, or by the associated parameters of mean biasing and nonlinearity (following Dekel & Lahav 1999). Using the

Aggeliki Kanaki, Costas G. Papadopoulos

HELAC is a FORTRAN based package that is able to compute efficiently helicity amplitudes for arbitrary scattering processes within the standard electroweak theory. The algorithm exploits the virtues of the Dyson-Schwinger equations as compared to the traditional Feynman graph approach. All electroweak vertices are included in both the unitary and Feynman gau

Z. G. Zhao

This presentation briefly summarizes the recent measurements of R-values in low energy e^+e^- annihilation. The new experiments aimed at reducing the uncertainties in R-values and performed with the upgraded Beijing Spectrometer (BESII) at Beijing Electron Positron Collider (BEPC) in Beijing and with CMD-2 and SND at VEEP-2M in Novosibirsk are reviewed and d

Mark Hale, Oliver Schwindt, Tom Weidig

The search for solutions of field theories allowing for topological solitons requires that we find the field configuration with the lowest energy in a given sector of topological charge. The standard approach is based on the numerical solution of the static Euler-Lagrange differential equation following from the field energy. As an alternative, we propose to

E. Conejero Jarque, F. Cornolti, A. Macchi, H. Ruhl

We investigate numerically effects related to ``single-cycle&#39;&#39; ionization of dense matter by an ultra-short laser pulse. The strongly non-adiabatic response of electrons leads to generation of a megagauss steady magnetic field in laser-solid interaction. By using two-beam interference, it is possible to create periodic density structures able to trap

Y. Bar-Yam

A historical dispute in the conceptual underpinnings of evolution is the validity of the gene centered view of evolution. \cite{dawkins,lewontin} We transcend this debate by formalizing the gene centered view as a dynamic version of the mean field approximation. This establishes the conditions under which it is applicable and when it is not. In particular, i

O. Teodorescu, A. K. Dutt-Mazumder, C. Gale

We study the possibility of $\rho-\delta$ mixing via N-N excitations in dense nuclear matter. This mixing induces a peak in the dilepton spectra at an invariant mass equal to that of the $\delta$. We calculate the cross section for dilepton production through the mixing process and we compare its size with that of $\pi-\pi$ annihilation. In-medium masses and

R. B. Wiringa, Steven C. Pieper, J. Carlson, V. R. Pandharipande

We report quantum Monte Carlo calculations of ground and low-lying excited states for A=8 nuclei using a realistic Hamiltonian containing the Argonne v18 two-nucleon and Urbana IX three-nucleon potentials. The calculations begin with correlated eight-body wave functions that have a filled alpha-like core and four p-shell nucleons LS-coupled to the appropriat

U. Mosel

The sensitivity of dilepton production in elementary reactions of photons and pions with nuclei on in-medium changes of hadronic properties is studied. It is shown that this sensitivity is comparable to that encountered in ultrarelativistic heavy-ion collisions. It is also shown how a significant broadening of the mesons affects other photonuclear processes.

K. Jungmann, :, g-2 collaboration

The muon magnetic anomaly may contain contributions from physics beyond the standard model. At the Brookhaven National Laboratory (BNL) a precision experiment aims for a measurement of the muon magnetic anomaly $a_μ$ to 0.35 ppm, where conclusions about various theoretical approaches beyond standard theory can be expected. The difference between the spin pre

Vladislav A. Bogoyavlenskiy, Natasha A. Chernova

We have combined the original diffusion-limited aggregation model introduced by Witten and Sander with the surface thermodynamics of the growing solid aggregate. The theory is based on the consideration of the surface chemical potential as a thermodynamic function of the temperature and nearest-neighbor configuration. The Monte Carlo simulations on a two-dim

F. Magri, G. Falqui, M. Pedroni

The aim of these lectures is to show that the methods of classical Hamiltonian mechanics can be profitably used to solve certain classes of nonlinear partial differential equations. The prototype of these equations is the well-known Korteweg-de Vries (KdV) equation. In these lectures we touch the following subjects: i) The birth and the role of the method of

G. Falqui, F. Magri, M. Pedroni

We discuss the bihamiltonian geometry of the Toda lattice (periodic and open). Using some recent results on the separation of variables for bihamiltonian manifolds, we show that these systems can be explicitly integrated via the classical Hamilton-Jacobi method in the so-called Darboux-Nijenhuis coordinates.

Katsuhiro Nishinari, Daisuke Takahashi

A family of multi-value cellular automaton (CA) associated with traffic flow is presented in this paper. The family is obtained by extending the rule-184 CA, which is an ultradiscrete analogue to the Burgers equation. CA models in the family show both metastable states and stop-and-go waves, which are often observed in real traffic flow. Metastable states in

Pavel Exner, Masao Hirokawa, Osamu Ogurisu

We consider a two-dimensional electron with an anomalous magnetic moment, g>2, interacting with a nonzero magnetic field B perpendicular to the plane which gives rise to a flux F. Recent results about the discrete spectrum of the Pauli operator are extended to fields with the O(r^{-2-δ}) decay at infinity: we show that if |F| exceeds an integer N, there is a

E. S. Cheb-Terrab, A. D. Roche

A systematic algorithm for building integrating factors of the form mu(x,y), mu(x,y&#39;) or mu(y,y&#39;) for second order ODEs is presented. The algorithm can determine the existence and explicit form of the integrating factors themselves without solving any differential equations, except for a linear ODE in one subcase of the mu(x,y) problem. Examples of O

Sagar A. Pandit, Anil D. Gangal

It is shown that the manifold S^3 can be equipped with a natural Nambu structure arising out of a cross product on the tangent space. Further, the group action of SU(2) on S^3 is shown to be Nambu action. Moreover, we compare the action of SU(2) on spinors with that of a Nambu system.

Kur. R. Myrzakul, R. Myrzakulov

Some aspects of the multidimensional soliton geometry are considered. It is shown that some simples (2+1)-dimensional equations are exact reductions of the Self-Dual Yang-Mills equation or its higher hierarchy.

A Knopfmacher, M E Mays

Graph compositions generalize both integer compositions and partitions of a finite set. We develop formulas, generating functions and recurrence relations for composition counting functions for several families of graphs.

José M. Isidro

Given a complex Hilbert space H and the von Neumann algebra L(H) of all bounded linear operators on H, we study the Grassmann manifold M of all projections in L(H) that have a fixed finite rank r. We take the Jordan-Banach triple theory approach which allows us to define a natural Levi-Civita connection on M. We identify the geodesics, compute the Riemann di

Nobuo Hara, Kei-ichi Watanabe

In this paper, we investigate the relationship of F-regular (resp. F-pure) rings and log terminal (resp. log canonical) singularities. Also, we extend the notions of F-regularity and F-purity to &#34;F-singularities of pairs.&#34; The notions of F-regular and F-pure rings in characteristic $p>0$ are characterized by a splitting of the Frobenius map, and defi

A. Chenaghlou, E. Corrigan

The sinh-Gordon model is restricted to a half-line by boundary conditions maintaining integrability. A perturbative calculation of the reflection factor is given to one loop order in the bulk coupling and to first order in the difference of the two parameters introduced at the boundary, providing a further verification of Ghoshal&#39;s formula. The calculati

I. Brevik, A. A. Bytsenko

The Casimir energy for the transverse oscillations of a piecewise uniform closed string is calculated. The great adaptibility of this string model with respect to various regularization methods is pointed out. We survey several regularization methods: the cutoff method, the complex contour integration method, and the zeta-function method. The most powerful m

C. Ekstrand

We use sets of trivial line bundles for the realization of gerbes. For 1-gerbes the structure arises naturally for the Weyl fermion vacuum bundle at a fixed time. The Schwinger term is an obstruction in the triviality of a 1-gerbe.

S. A. Bulgadaev

The D-dimensional conformal nonlinear sigma-models (NSM) sre constructed. It is shown that the NSM on spaces with $π_{D-1} = \mathbb {Z}$ have the topological solutions of a &#34;hedgehog&#34; and &#34;anti-hedgehog&#34; types with logarithmic energies. For spaces with $π_D \ne 0$ they have also the topological excitations of instanton types with finite ener

Antonio Soares de Castro, Jerrold Franklin

Exact solutions are found to the Dirac equation for a combination of Lorentz scalar and vector Coulombic potentials with additional non-Coulombic parts. An appropriate linear combination of Lorentz scalar and vector non-Coulombic potentials, with the scalar part dominating, can be chosen to give exact analytic Dirac wave functions. The method works for the g

Juan Maldacena

We explain the need for a theory of quantum gravity and some general ideas about string theory, including the idea of the derivation of the Hawking Bekenstein entropy formula for extremal black holes. We then give a general description of the correspondence between the large N limit of certain gauge theories and string theory on spacetimes with boundaries.

Francesca Rosati

The most recent cosmological data point in the direction of a cosmological constant dominated universe. A suitable candidate for providing the required acceleration is a rolling scalar field named ``quintessence&#39;&#39;. We address the issue of building a particle physics model for quintessence in the context of Susy QCD. We then go on to ask if the quinte

R. M. Woloshyn

Hadron masses are calculated in quenched lattice QCD with a fermion action of the D234 type on an anisotropic lattice. Hyperfine splittings for singly charmed baryons are found to be in agreement with expectations from the quark model and with a magnitude slightly larger than experimental values. Masses of doubly charmed baryons are also calculated and compa

Hendrik van Hees, Jörn Knoll

Within a field theoretical model where all damping width effects are treated self-consistently we study the changes of the spectral properties of rho-mesons due to the finite damping width of the pions in dense hadronic matter at finite temperature. The corresponding effects in the di-lepton yields are presented. Some problems concerning the self consistent

R. Buras

We investigate analytically the evolution of the primordial neutrino asymmetry caused by active-sterile neutrino oscillations. In particular, we concentrate on possible chaotic oscillations of the asymmetry. For a certain range of parameters, we find that the asymmetry indeed oscillates, provided we neglect the momentum distribution.

B. Loiseau, T. E. O. Ericson

The Coulomb-like backward peak of the neutron-proton scattering differential cross section is due to one-pion exchange. Extrapolation to the pion pole of precise data should allow to obtain the value of the charged pion-nucleon coupling constant. This was classically attempted by the use of a smooth physical function, the Chew function, built from the cross

V. A. Kuz&#39;menko

A direct experimental proof of very strong T-invariance violation in interactions of the photons with atoms and molecules exists in the molecular physics.