December 2000 arXiv papers — page 9

M. A. Martin-Delgado, J. Rodriguez-Laguna, G. Sierra

We introduce the density matrix renormalization group (DMRG) method as an efficient computational tool for one-exciton approximations with off-diagonal disorder. This method allows us to reduce the computational effort by targetting only a few low-lying eigenstates at each statistical sampling, in contrast to the exact diagonalization methods that compute th

M. Basset, G. Jakob, G. Wirth, H. Adrian

We present a new experiment on YBa_2Cu_3O_{7-x} (YBCO) thin films using spatially resolved heavy ion irradiation. Structures consisting of a periodic array of strong and weak pinning channels were created with the help of metal masks. The channels formed an angle of +/-45 Deg with respect to the symmetry axis of the photolithographically patterned structures

C. N. Brosseau, M. Poirier, R. Suryanarayanan, G. Dhalenne

We have studied the magneto-elastic coupling in the double layered Mn perovskite La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$ with an ultrasonic velocity technique. The temperature profile of both the in-plane and out-of-plane longitudinal velocities showed a large stiffening anomaly below the insulating paramagnetic to metallic ferromagnetic transition. Magnetic fluctua

Charles Santori, Matthew Pelton, Glenn Solomon, Yseulte Dale

We demonstrate a new method for generating triggered single photons. After a laser pulse generates excitons inside of a single quantum dot, electrostatic interactions between them and the resulting spectral shifts allow a single emitted photon to be isolated. Autocorrelation measurements show a reduction of the two-photon probability to 0.12 times the value

P. Capuzzi, E. S. Hernandez

We present a Random-Phase-Approximation formalism for the collective spectrum of two hyperfine species of dilute 40K atoms, magnetically trapped at zero temperature and subjected to a repulsive s-wave interaction between atoms with different spin projections. We examine the density-like and the spin-like oscillation spectra, as well as the transition density

András Csordás, Robert Graham

The hydrodynamic equations of an ideal fluid formed by a dilute quantum gas in a parabolic trapping potential are studied analytically and numerically. Due to the appearance of internal modes in the fluid stratified by the trapping potential, the spectrum of low-lying modes is found to be dense in the high-temperature limit, with an infinitely degenerate set

Qimiao Si

Hill et al. have recently measured both the thermal and charge conductivities in the normal state of a high temperature superconductor. Based on the vanishing of the Wiedemann-Franz ratio in the extrapolated zero temperature limit, they conclude that the charge carriers in this material are not fermionic. Here I make a simple observation that the prefactor i

Benedict J. Cusack, Tristram J. Alexander, Elena A. Ostrovskaya, Yuri S. Kivshar

We analyze the model of an atomic Bose-Einstein condensate (BEC) parametrically coupled to a molecular BEC via a photoassociation process. We show that an interplay of nonlinear inter- and intra-species interactions leads to the formation of mutually trapped states of a hybrid condensate, which are spatially localized even without a trap. The untrapped atomi

Ya. V. Fominov, M. V. Feigel'man

The theory of superconductivity in thin SN sandwiches (bilayers) in the diffusive limit is developed within the standard Usadel equation method, with particular emphasis on the case of very thin superconductive layers, d_S << d_N. The proximity effect in the system is governed by the interlayer interface resistance (per channel) ρ_{int}. The case of relative

L. A. Phillips, J. P. Ostriker

At low redshifts, measurements of the total baryon content in stars, atomic and molecular hydrogen, and cluster gas fall a factor of two to four below the baryon density derived from observed light-element ratios and nucleosynthesis arguments. A possible hiding place for a significant fraction of the missing baryons is in the warm/hot gas at temperatures T =

Gerhard Suttner, Harold W. Yorke

We investigate dust dynamics and evolution during the formation of a protostellar accretion disk around intermediate mass stars via 2D numerical simulations. Using three different detailed dust models, compact spherical particles, fractal BPCA grains, and BCCA grains, we find that even during the early collapse and the first 10,000 yr of dynamical disk evolu

Gordon T. Richards, Xiaohui Fan, Donald P. Schneider, Daniel E. Vanden Berk

We present an empirical investigation of the colors of quasars in the Sloan Digital Sky Survey (SDSS) photometric system. The sample studied includes 2625 quasars with SDSS photometry. The quasars are distributed in a 2.5 degree wide stripe centered on the Celestial Equator covering $\sim529$ square degrees. Positions and SDSS magnitudes are given for the 89

K. Nandra

Rapid flux changes in the X-ray emission from active galactic nuclei are commonly observed. The power-density spectra show a pseudo power-law form with a turnover at low frequencies and a high frequency break, similar to galactic black-hole candidates. There have been a few claims for periodicities but these are not a well-established property of the class.

Lisa J. Storrie-Lombardi, Michael J. Irwin, Richard G. McMahon, Isobel M. Hook

We present the spectra, positions, and finding charts for 31 bright (R<19.3) colour-selected quasars covering the redshift range z=3.85-4.78, with 4 having redshifts z>4.5. The majority are in the southern sky (dec<-25 deg). The quasar candidates were selected for their red (B-R > 2.5) colours from UK or POSSII Schmidt Plates scanned at the Automated Plate M

John E. Gizis, J. Davy Kirkpatrick, John C. Wilson

We report the discovery of a probable L1 companion to the nearby K2 dwarf GJ 1048 using the Two Micron All-Sky Survey (2MASS). This source, 2MASSI J0235599-233120 or GJ 1048B, has 2MASS near-infrared colors and absolute magnitudes consistent with an early L dwarf companion with a projected separation of 250 A.U. The L1 spectral type is confirmed by far-red o

Anvar Shukurov

Recent numerical simulations of the interstellar medium driven by energy input from supernovae and stellar winds indicate that HI clouds can be formed by compression in shock waves and colliding turbulent streams without any help from thermal and gravitational instabilities. The filling factor of the hot phase in these models does not exceed 20-40% at the mi

Riccardo Giovanelli

With plans to build a large IR/optical telescope in the Atacama Desert, a site survey campaign has been underway since 1998 to characterize the optical seeing and the IR transparency in the Chajnantor Plateau region. Preliminary results indicate that the Chajnantor region offers excellent astronomical observing conditions in the optical and IR. The region is

David J. Helfand, Remington P. S. Stone, Beth Willman, Richard L. White

We have obtained single-epoch optical photometry for 201 quasars, taken from the FIRST Bright Quasar Survey, which span a wide range in radio loudness. Comparison with the magnitudes of these objects on the POSS-I plates provides by far the largest sample of long-term variability amplitudes for radio-selected quasars yet produced. We find the quasars to be m

V. Stanishev, Z. Kraicheva, H. M. J. Boffin, V. Genkov

CCD photometry of the newly discovered eclipsing dwarf nova IY UMa is used to study the physical properties of the accretion disc in the late decline and quiescence stages. Eclipse mapping analysis shows that in these stages the accretion disc is cool with approximately flat radial brightness temperature distribution and T_BR about 5000-5500 K. The hot spot

E. van der Swaluw, A. Achterberg, Y. A. Gallant, G. Tóth

A spherically symmetric model is presented for the interaction of a pulsar wind with the associated supernova remnant. This results in a pulsar wind nebula whose evolution is coupled to the evolution of the surrounding supernova remnant. This evolution can be divided in three stages. The first stage is characterised by a supersonic expansion of the pulsar wi

S. Borgani, L. Guzzo

Clusters of galaxies outline the network of the distribution of visible matter in the Universe, marking the highest-mass knots where filamentary structures join together. If we observe the sky in X rays, clusters of galaxies stand out as cosmic lighthouses by virtue of a thin gas trapped and heated within their gravitational potential wells. This powerful em

Jens Thomas, Hartmut Schulz

Various classification schemes exist for homogeneous and isotropic (CP) world models, which include pressureless matter (so-called dust) and Einstein&#39;s cosmological constant Lambda. We here classify the solutions of more general world models consisting of up to four non-interacting fluids, each with pressure P, energy density epsilon and an equation of s

H. J. Deeg, R. Garrido, A. Claret

Multicolor photometric observations of a planetary transit in the system HD 209458 are analyzed. The observations, made in the Stromgren photometric system, allowed a recalculation of the basic physical properties of the star-planet system. This includes derivation of linear limb-darkening values of HD 209458, which is the first time that a limb-darkening se

J. M. Pittard, J. E. Dyson, T. W. Hartquist

We present similarity solutions for mass-loaded adiabatic bubbles that are blown by winds having time dependent mechanical luminosities. We consider mass-loading through conductive evaporation of clumps. In the limit of little mass loading a similarity solution found by Dyson (1973) for expansion into a smooth ambient medium is recovered. We find that the Ma

David A. Kornreich, Martha P. Haynes, Katherine P. Jore, R. V. E. Lovelace

We have examined the morphological and dynamical HI symmetry properties of a sample of moderately inclined Sa galaxies which are classified as morphologically normal. The sample galaxies were known a prior to exhibit kinematic peculiarities ranging from warps to independent, wholly decoupled disks, and are possibly the remnants of minor mergers. We compare t

S. Karino, S. Yoshida, Y. Eriguchi

For the analysis of the r-mode oscillation of hot young neutron stars, it is necessary to consider the effect of it differential rotation, because viscosity is not strong enough for differentially rotating young neutron stars to be lead to uniformly rotating configurations on a very short time scale after their birth. In this paper, we have developed a numer

Daniele Dallacasa, Carlo Stanghellini, Matteo Centonza, Roberto Fanti

Here we present a sample of sources with convex radio spectra peaking at frequencies above a few GHz. We call these radio sources High Frequency Peakers (HFPs). This sample extends to higher turnover frequencies than the samples of Compact Steep Spectrum (CSS) and GHz Peaked Spectrum (GPS) radio sources. HFPs are rare due to the strong bias against them caus

S. Singh, N. Chandrika Devi, V. K. Gupta, Asha Gupta

In this paper we study radial oscillations of rotating strange stars in strong magnetic fields in the Density Dependent Quark Mass (DDQM) model. We see that increase of frequency i.e. difference in frequency of rotating and non-rotating stars is more for higher magnetic fields. The change is small for low mass stars but it increases with the mass of the star

Kerstin Weis, Wolfgang J. Duschl, Dominik J. Bomans

The Luminous Blue Variable star Eta Carinae is one of the most massive stars known. It underwent a giant eruption in 1843 in which the Homunculus nebula was created. ROSAT and ASCA data indicate the existence of a hard and a soft X-ray component which appear to be spatially distinct: a softer diffuse shell of the nebula around Eta Carinae and a harder point-

Michele Cappellari, Francesco Bertola, David Burstein, Lucio M. Buson

The nucleus of the bulge-dominated, multiply-barred S0/a galaxy NGC 2681 is studied in detail, using high resolution Hubble Space Telescope FOC and NICMOS imaging and FOS spectroscopy. The ionised gas central velocity dispersion is found to increase by a factor ~2 when narrowing the aperture from R~1.5&#34; (ground) to R~0.1&#34; (FOS). Dynamical modeling of

D. G. Yakovlev, O. Y. Gnedin, A. Y. Potekhin

Matter of subnuclear density in the inner crusts of neutron stars consists of neutron-rich atomic nuclei immersed in strongly degenerate relativistic gas of electrons and strongly nonideal liquid of neutrons. We give a brief account of thermodynamic and kinetic properties of this matter which are greatly affected by Coulomb and nuclear interactions (a compan

Joachim Wambsganss

Gravitational lensing has established itself as a valuable tool in many astrophysical fields in the roughly 20 years of its existence as an observational science. In this brief review, first the basics of lensing are introduced. Then it is shown that the two propagation effects, gravitational lensing and interstellar scintillation, have a number of propertie

R. Stompor, A. Balbi, J. Borrill, P. Ferreira

We review selected methods of the Cosmic Microwave Background data analysis appropriate for the analysis of the largest currently available data sets. We focus on techniques of the time-ordered data manipulation and map making algorithms based on the maximum-likelihood approach. The presented methods have been applied to the MAXIMA data analysis (Hanany et a

Timothy R. Bedding, R. Paul Butler, Hans Kjeldsen, Ivan K. Baldry

We have made a clear detection of excess power, providing strong evidence for solar-like oscillations in the G2 subgiant beta Hyi. We observed this star over five nights with the UCLES echelle spectrograph on the 3.9-m Anglo-Australian Telescope, using an iodine absorption cell as a velocity reference. The time series of 1196 velocity measurements shows an r

Anvar R. Mavlyutov

This paper explicitly describes Hodge structures of complete intersections of ample hypersurfaces in compact simplicial toric varieties.

Edward Dobson, Dave Witte

We explicitly determine all of the transitive groups of degree p-squared, p a prime, whose Sylow p-subgroup is not the wreath product of two cyclic groups of order p. Furthermore, we provide a general description of the transitive groups of degree p-squared whose Sylow p-subgroup is such a wreath product, and explicitly determine most of them. As application

I. H. Stairs, R. N. Manchester, A. G. Lyne, V. M. Kaspi

We report on the discovery of a binary pulsar, PSR J1740-3052, during the Parkes multibeam survey. Timing observations of the 570-ms pulsar at Jodrell Bank and Parkes show that it is young, with a characteristic age of 350 kyr, and is in a 231-day, highly eccentric orbit with a companion whose mass exceeds 11 M_sun. An accurate position for the pulsar was ob

D. A. Dicus, C. D. McMullen, S. Nandi

We consider an asymmetric string compactification scenario in which the SM gauge bosons can propagate into one TeV$^{-1}$-size extra compact dimension. These gauge bosons have associated KK excitations that present additional contributions to the SM processes. We calculate the effects that the KK excitations of the gluons, $g^{\star}$&#39;s, have on multijet

Valeriy V. Dvoeglazov

I discuss generalized spin-1/2 equations for neutrinos. They have been obtained by means of the Gersten&#39;s method for derivation of arbitrary-spin relativistic equations. Possible physical consequences are discussed.

Alan D. Sokal

I show that the zeros of the chromatic polynomials P_G(q) for the generalized theta graphs Θ^{(s,p)} are, taken together, dense in the whole complex plane with the possible exception of the disc |q-1| < 1. The same holds for their dichromatic polynomials (alias Tutte polynomials, alias Potts-model partition functions) Z_G(q,v) outside the disc |q+v| < |v|. A

Kevin R. Lynch, Elizabeth H. Simmons

LEPI and LEPII data can be used to constrain technicolor models with light, neutral pseudo-Nambu-Goldstone bosons, Pa. We use published limits on branching ratios and cross sections for final states with photons, large missing energy, jet pairs, and b bbar pairs to constrain the anomalous Pa Z0 Z0, Pa Z0 photon, and Pa photon photon couplings. From these res

G. K. Leontaris, J. Rizos

We explore the possibility of embedding the Pati-Salam model in the context of Type I brane models. We study a generic model with U(4)_C x U(2)_L x U(2)_R gauge symmetry and matter fields compatible with a Type I brane configuration. Examining the anomaly cancellation conditions of the surplus abelian symmetries we find an alternative hypercharge embedding t

Brian C. Hall

Let K be a connected Lie group of compact type and let T*(K) be its cotangent bundle. This paper considers geometric quantization of T*(K), first using the vertical polarization and then using a natural Kahler polarization obtained by identifying T*(K) with the complexified group K_C. The first main result is that the Hilbert space obtained by using the Kahl

Theodore E. Liolios

Multi-electron screening effects encountered in laboratory astrophysical reactions are investigated by considering the reactants Thomas-Fermi atoms. By means of that model, previous studies are extended to derive the corresponding screening enhancement factor (SEF), so that it takes into account ionization, thermal, exchange and relativistic effects. The pre

M. J. Church

X-ray dipping in the black hole binary Cygnus X-1, the Galactic jet source GRO J1655-40 and in low mass X-ray binaries is discussed. It is shown that spectral analysis strongly constrains emission models. Measurement of dip ingress/egress times allows the sizes of extended emission regions to be determined, notably for the Accretion Disk Corona which is resp

Theodore E. Liolios

Effective astrophysical factors for non-resonant astrophysical nuclear reaction are invariably calculated with respect to a zero energy limit. In the present work that limit is shown to be very disadvantageous compared to the more natural effective energy limit. The latter is used in order to modify the thermonuclear reaction rate formula so that it takes in

Jerome P. Gauntlett, David Tong, Paul K. Townsend

Massive maximally-supersymmetric sigma models are shown to exhibit multiple static kink-domain wall solutions that preserve 1/2 of the supersymmetry. The kink moduli space admits a natural Kahler metric. We examine in some detail the case when the target of the sigma model is given by the co-tangent bundle of CP^n equipped with the Calabi metric, and we show

Shi-Lin Zhu, S. Puglia, B. R. Holstein, M. J. Ramsey-Musolf

We compute the photon asymmetry $B_γ$ for near threshold parity violating (PV) pion photoproduction through sub-leading order. We show that sub-leading contributions involve a new combination of PV couplings not included in previous analyses of hadronic PV. We argue that existing constraints on the leading order contribution to $B_γ$ -- obtained from the PV

Dario Trevese, Richard G. Kron, Alessandro Bunone

The variability of the continuum spectral energy distribution has been analyzed for a complete magnitude-limited sample of quasars in Selected Area 57, observed at two epochs in the photographic $U$, $B_J$, $F$ and $N$ bands with the Mayall 4m telescope at Kitt Peak. Changes $δα$ of the spectral slope $α$ appear correlated with brightness variations $δlog f_

E. Deotto, E. Gozzi

In this paper we continue the study of the geometrical features of a functional approach to classical mechanics proposed some time ago. In particular we try to shed some light on a N=2 &#34;universal&#34; supersymmetry which seems to have an interesting interplay with the concept of ergodicity of the system. To study the geometry better we make this susy loc

Karol Zyczkowski, Hans-Juergen Sommers

We analyze several product measures in the space of mixed quantum states. In particular we study measures induced by the operation of partial tracing. The natural, rotationally invariant measure on the set of all pure states of a N x K composite system, induces a unique measure in the space of N x N mixed states (or in the space of K x K mixed states, if the

M. Chaichian, A. Demichev, P. Presnajder, M. M. Sheikh-Jabbari

The Aharonov-Bohm effect on the noncommutative plane is considered. Developing the path integral formulation of quantum mechanics, we find the propagation amplitude for a particle in a noncommutative space. We show that the corresponding shift in the phase of the particle propagator due to the magnetic field of a thin solenoid receives certain gauge invarian

Stefan Keppeler

Starting from a semiclassical quantization condition based on the trace formula, we derive a periodic-orbit formula for the distribution of spacings of eigenvalues with k intermediate levels. Numerical tests verify the validity of this representation for the nearest-neighbor level spacing (k=0). In a second part, we present an asymptotic evaluation for large

Carlo A. Trugenberger

Typical address-oriented computer memories cannot recognize incomplete or noisy information. Associative (content-addressable) memories solve this problem but suffer from severe capacity shortages. I propose a model of a quantum memory that solves both problems. The storage capacity is exponential in the number of qbits and thus optimal. The retrieval mechan

L. L. Salcedo

Explicit exact formulas are presented, up to fourth order in a strict chiral covariant derivative expansion, for the normal parity component of the Euclidean effective action of even-dimensional Dirac fermions. The bosonic background fields considered are scalar, pseudo-scalar, vector and axial vector. No assumptions are made on the internal symmetry group a

L. L. Salcedo

Explicit exact formulas are presented, for the leading order term in a strict chiral covariant derivative expansion, for the abnormal parity component of the effective action of two- and four-dimensional Dirac fermions in presence of scalar, pseudo-scalar, vector and axial vector background fields. The formulas hold for completely general internal symmetry g

Thibault Damour, Marc Henneaux

It is shown that the never ending oscillatory behaviour of the generic solution, near a cosmological singularity, of the massless bosonic sector of superstring theory can be described as a billiard motion within a simplex in 9-dimensional hyperbolic space. The Coxeter group of reflections of this billiard is discrete and is the Weyl group of the hyperbolic K

R. Brinzanik, P. J. Jensen, K. H. Bennemann

The nonequilibrium magnetic domain structure of growing ultrathin ferromagnetic films with a realistic atomic structure is studied as a function of coverage and temperature. We apply a kinetic Monte Carlo method to a micromagnetic model describing the transition from superparamagnetic islands at low coverages to a closed ferromagnetic film. The magnetic rela

Jiliang Jing, Mu-Lin Yan

By using the Newman-Penrose formalism and &#39;t Hooft brick-wall model, the quantum entropies of the Kerr-Newman black hole due to the Dirac and electromagnetic fields are calculated and the effects of the spins of the photons and Dirac particles on the entropies are investigated. It is shown that the entropies depend only on the square of the spins of the

Kikuo Harigaya, Naoki Kawatsu, Toshiaki Enoki

Antiferromagnetism in stacked nanographite is investigated with using the Hubbard-type model. The A-B stacking is favorable for the hexagonal nanographite with zigzag edges, in order that magnetism appears. Next, we find that the open shell electronic structures can be origins of the decreasing magnetic moment with the decrease of the inter-graphene distance

F. Ruiz Ruiz

It is argued that the quadratic and linear non-commutative IR divergences that occur in U(1) theory on non-commutative Minkowski spacetime for small non-commutativity matrices $θ^{μν}$ are gauge-fixing independent. This implies in particular that the perturbative tachyonic instability produced by the quadratic divergences of this type in the vacuum polarizat

Jose Bordes, Chan Hong-Mo, Ricardo Gallego, Tsou Sheung Tsun

The Dualized Standard Model offers a {\it raison d&#39;être} for 3 fermion generations and an explanation for their distinctive mass and mixing patterns, reproducing to a reasonable accuracy the empirical mixing matrix and mass spectrum for both quarks and leptons in terms of just a few parameters. With its parameters thus fixed, the result is a highly predi

A. Dhar, Y. Kitazawa

We investigate the high energy behavior of the correlation functions of the open Wilson lines in noncommutative gauge theory. We obtain a very simple physical picture that they are bound to form a group of closed Wilson loops. We prove our claim in the weak coupling region by perturbative analysis. We emphasize the importance of respecting the cyclic symmetr

I. V. Kolokolov, V. V. Lebedev

We consider asymptotics of the velocity derivatives probability distribution functions (PDFs) in Burgers&#39; turbulence. We argue that in the forced case the same power laws as in the decaying case are realized for an infinite system.

E. Sezgin, P. Sundell

We examine the curvature expansion of a the field equations of a four-dimensional higher spin gauge theory extension of anti-de Sitter gravity. The theory contains massless particles of spin 0,2,4,... that arise in the symmetric product of two spin 0 singletons. We cast the curvature expansion into manifestly covariant form and elucidate the structure of the

M. Frau, L. Gallot, A. Lerda, P. Strigazzi

We review the boundary state description of D-branes in type I string theory and show that the only stable non-BPS configurations are the D-particle and the D-instanton. We also compute the gauge and gravitational interactions of the non-BPS D-particles and compare them with the interactions of the dual non-BPS states of the heterotic string, finding complet

Sei-Hoon Moon, Soo-Jong Rey, Yoon-Bai Kim

We find a class of extremal black hole-like global p-brane in higher-dimensional gravity with a negative cosmological constant. The region inside the p-brane horizon possesses all essential features required for the Randall-Sundrum-type brane world scenario. The set-up allows to interpret the horizon size as the compactification size in that the Planck scale

Andrei Barvinsky, Saurya Das, Gabor Kunstatter

Following an earlier suggestion of the authors(gr-qc/9607030), we use some basic properties of Euclidean black hole thermodynamics and the quantum mechanics of systems with periodic phase space coordinate to derive the discrete two-parameter area spectrum of generic charged spherically symmetric black holes in any dimension. For the Reissner-Nordstrom black

Charles H. Lineweaver

Planets like the Earth cannot form unless elements heavier than helium are available. These heavy elements, or `metals&#39;, were not produced in the big bang. They result from fusion inside stars and have been gradually building up over the lifetime of the Universe. Recent observations indicate that the presence of giant extrasolar planets at small distance

Donato Bini, Robert T. Jantzen, Bahram Mashhoon

The gravitomagnetic clock effect and the Sagnac effect for circularly rotating orbits in stationary axisymmetric spacetimes are studied from a relative observer point of view, clarifying their relationships and the roles played by special observer families. In particular Semerák&#39;s recent characterization of extremely accelerated observers in terms of the

G. P. Berman, F. Borgonovi, F. M. Izrailev, V. I. Tsifrinovich

We study a one-dimensional chain of nuclear $1/2-$spins in an external time-dependent magnetic field. This model is considered as a possible candidate for experimental realization of quantum computation. According to the general theory of interacting particles, one of the most dangerous effects is quantum chaos which can destroy the stability of quantum oper

Andrew M. Childs, Edward Farhi, Jeffrey Goldstone, Sam Gutmann

Quantum adiabatic evolution provides a general technique for the solution of combinatorial search problems on quantum computers. We present the results of a numerical study of a particular application of quantum adiabatic evolution, the problem of finding the largest clique in a random graph. An n-vertex random graph has each edge included with probability 1

Ho Trung Dung, Ludwig Knöll, Dirk-Gunnar Welsch

Spontaneous decay of an excited atom near a dispersing and absorbing microsphere of given complex permittivity that satisfies the Kramers-Kronig relations is studied, with special emphasis on a Drude-Lorentz permittivity. Both the whispering gallery field resonances below the band gap (for a dielectric sphere) and the surface-guided field resonances inside t

V. M. Akulin, V. Gershkovich, G. Harel

We analyze the possibility and efficiency of non-holonomic control over quantum devices with exponentially large number of Hilbert space dimensions. We show that completely controllable devices of this type can be assembled from elementary units of arbitrary physical nature, and can be employed efficiently for universal quantum computations and simulation of

Manu Mathur, Diptiman Sen

We define coherent states for SU(3) using six bosonic creation and annihilation operators. These coherent states are explicitly characterized by six complex numbers with constraints. For the completely symmetric representations (n,0) and (0,m), only three of the bosonic operators are required. For mixed representations (n,m), all six operators are required.

T. Lari

Standard as well as irradiated silicon pixel detectors developed for the ATLAS experiment were tested in a beam. Digital and analog resolutions were determined comparing the positions measured by a microstrip telescope and by the pixel detector. Digital resolutions of 10 um and analog resolutions of 6 um (before irradiation) and 10 um (after irradiation) are

F. Cattani, A. Kim, D. Anderson, M. Lisak

A simple model is derived to prove the multi-filament structure of relativistic self-focusing with ultra-intense lasers. Exact analytical solutions describing the transverse structure of waveguide channels with electron cavitation, for which both the relativistic and ponderomotive nonlinearities are taken into account, are presented.

Guy Chanfray

Recent developments on medium modifications of hadron properties in dense and hot hadronic matter are discussed. I will focus in particular on the behavior of spectral functions associated to collective scalar-isoscalar modes, kaons and vector mesons from ordinary nuclear matter to highly excited matter produced in relativistic heavy-ion collisions from SIS

Martin Oettel

In this thesis a model framework for describing baryons as diquark-quark bound states is presented which is formulated in an explicitly covariant manner. The relativistic bound state problem for three quarks is considered. Diquarks are introduced as separable correlations in the two-quark correlation function and thereby baryons are described by a Bethe-Salp

Hartmuth Arenhoevel, Shri K. Singh

The general formalism for polarization observables in elastic electron deuteron scattering is extended to incorporate parity and time reversal violating contributions. Parity violating effects arise from the interference of $γ$ and $Z$ exchange as well as from the hadronic sector via a small parity violating component in the deuteron. In addition we have all

Anders Berntson, Boris A. Malomed

A model of a long optical communication line consisting of alternating segments with anomalous and normal dispersion, whose lengths are picked up randomly from a certain interval, is considered. At the first stage of the analysis, we calculate small changes of parameters of a quasi-Gaussian pulse passing a two-segment cell by means of the variational approac

N. V. Ustinov, Yu. V. Brezhnev

A way to derive an explicit formulae in terms of the potentials, if they are finite-gap, for the solutions of spectral problems and corresponding algebraic curves is presented.

T. Shimada, S. Tsukada

We revisit the globally coupled map lattice (GCML). We use a family of universal &#39;curves of balance&#39; between two conflicting tendencies in the model- the randomness in each map and the coherence due to an averaging interaction - and we locate the posi-nega switch region in the parameter space of the model. We clarify the mechanism of a basic posi-neg

Cyriaque Atindogbe, Jean-Pierre Ezin, Joël Tossa

We give a sufficient condition for a lightlike isotropic submanifold $M$, of dimension $n$, which is not totally geodesic in a semi-Riemannian manifold of constant curvature $c$ and of dimension $n+p (n < p)$, to admit a reduction of codimension. We show that this condition is a necessary and sufficient condition on the first transversal space of $M$. There

Nicolai Reshetikhin, Milen Yakimov

Let (M, \om) be a symplectic manifold. A Lagrangian fiber bundle π: M -> B determines a completely integrable system on M. First integrals of this system are the pull-backs of functions on the base of the bundle. We show that for each Lagrangian fiber bundle πthere exist star products on C^\infty(M)[[h]] which do not deform the pointwise multiplication on th

F. Alberto Grünbaum, Milen Yakimov

We construct families of bispectral difference operators of the form a(n)T + b(n) + c(n) T^{-1} where T is the shift operator. They are obtained as discrete Darboux transformations from appropriate extensions of Jacobi operators. We conjecture that along with operators previously constructed by Grunbaum, Haine, Horozov, and Iliev they exhaust all bispectral

W. Zwonek

We construct a bounded plane domain which is Bergman complete but for which the Bergman kernel does not tend to infinity as the point approaches the boundary.

P. Pflug, W. Zwonek

We give a characterization of $L_h^2$-domains of holomorphy with the help of the boundary behavior of the Bergman kernel and geometric properties of the boundary, respectively.

Oleg Kovrizhkin

We prove several results related to the theorem of Logvinenko and Sereda on determining sets for functions with Fourier transforms supported in an interval. We obtain a polynomial instead of exponential bound in this theorem, and we extend it to the case of functions with Fourier transforms supported in the union of a bounded number of intervals. The same re

Johannes Huebschmann

Playing off against each other the real and complex structures, we elucidate the local structure of certain representation spaces in the world of Poisson geometry. Particular cases of these spaces arise as moduli spaces of semistable holomorphic vector bundles on Riemann surfaces.

G. F. Vincent-Smith

The quantum Ito formula has so far been proved for regular (bounded) quantum semimartingales We give three different extensions to classes of essentially self-adjoint (unbounded) quantum semimartingales. The first extension is to quantum semimartingales whose integrands have chaos matrices controlled by certain scalar matrices The second extension is to pert

E. Ragoucy

We show that the truncation of twisted Yangians are isomorphic to finite W-algebras based on orthogonal or symplectic algebras. This isomorphism allows us to classify all the finite dimensional irreducible representations of the quoted W-algebras. We also give an R-matrix for these W-algebras, and determine their center.

E. C. M. Crooks

We are concerned with the asymptotic behaviour of classical solutions of systems of the form u_t = Au_xx + f(u, u_x), x in R, t>0, u(x,t) a vector in RN, with u(x,0)= U(x), where A is a positive-definite diagonal matrix and f is a &#39;bistable&#39; nonlinearity satisfying conditions which guarantee the existence of a comparison principle. Suppose that there

Adrian Langer

We introduce orbifold Euler numbers for normal surfaces with Q-divisors. These numbers behave multiplicatively under finite maps and in the log canonical case we prove that they satisfy the Bogomolov-Miyaoka-Yau type inequality. As a corollary we prove effective versions of Bogomolov&#39;s result on boundedness of rational curves in some surfaces of general

Ali Ulas Ozgur Kisisel

We define a convolution operation on the set of polyominoes and use it to obtain a criterion for a given polyomino not to tile the plane (rotations and translations allowed). We apply the criterion to several families of polyominoes, and show that the criterion detects some cases that are not detectable by generalized coloring arguments.

Eduardo J. Dubuc

In Proposition I of &#34;Memoire sur les conditions de resolubilite des equations par radicaux&#34;, Galois established that any intermediate extension of the splitting field of a polynomial with rational coefficients is the fixed field of its galois group. We first state and prove the (dual) categorical interpretation of of this statement, which is a theore

Pirkko Kuusela, Daniel Ocone, Eduardo D. Sontag

This paper takes a computational learning theory approach to a problem of linear systems identification. It is assumed that input signals have only a finite number k of frequency components, and systems to be identified have dimension no greater than n. The main result establishes that the sample complexity needed for identification scales polynomially with

Marco Manetti

In 1932 F. Severi claimed, with an incorrect proof, that every smooth minimal projective surface $S$ such that the bundle $Ω^1_S$ is generically generated by global sections satisfies the topological inequality $2c_1^2(S)\ge c_2(S)$. According to Enriques-Kodaira classification, the above inequality is easily verified when the Kodaira dimension of the surfac

Kentaro Hori

We construct a class of supersymmetric boundary interactions in N=2 field theories on the half-space, which depend on parameters that are not at all renormalized or not renormalized in perturbation theory beyond one-loop. This can be used to study D-branes wrapped on a certain class of Lagrangian submanifolds as well as holomorphic cycles. The construction o

L. A. Ferreira, A. V. Razumov

We consider a (3+1)-dimensional local field theory defined on the sphere. The model possesses exact soliton solutions with non trivial Hopf topological charges, and infinite number of local conserved currents. We show that the Poisson bracket algebra of the corresponding charges is isomorphic to that of the area preserving diffeomorphisms of the sphere. We a