November 2000 arXiv papers — page 6

Enzo Granato, S. C. Ying

We study the response of an adsorbed monolayer under a driving force as a model of sliding friction phenomena between two crystalline surfaces with a boundary lubrication layer. Using Langevin-dynamics simulation, we determine the nonlinear response in the direction transverse to a high symmetry direction along which the layer is already sliding. We find tha

P. M. Ricker, A. C. Calder, L. J. Dursi, B. Fryxell

We discuss some of the computational challenges encountered in simulating the evolution of clusters of galaxies. Eulerian adaptive mesh refinement (AMR) techniques can successfully address these challenges but are currently being used by only a few groups. We describe our publicly available AMR code, FLASH, which uses an object-oriented framework to manage i

John F. Hawley

This paper presents a series of global three dimensional accretion disk simulations carried out in the cylindrical limit in which the vertical component of the gravitational field is neglected. The simulations use a cylindrical pseudo-Newtonian potential to model the main dynamical properties of the Schwarzschild metric. The disks are initially constant dens

Patrick McCarthy, Ray Carlberg, Ron Marzke, Hsiao-Wen Chen

We report results from the first 1000 square arc-minutes of the Las Campanas IR survey. We have imaged 1 square degree of high latitude sky in six distinct fields to a 5-sigma H-band depth of 20.5 (Vega). Optical imaging in the V,R,I,and z' bands allow us to select color subsets and photometric-redshift-defined shells. We show that the angular clustering

M. J. L. Turner, A. Abbey, M. Arnaud

The EPIC focal plane imaging spectrometers on XMM-Newton use CCDs to record the images and spectra of celestial X-ray sources focused by the three X-ray mirrors. There is one camera at the focus of each mirror; two of the cameras contain seven MOS CCDs, while the third uses twelve PN CCDs, defining a circular field of view of 30 arcmin diameter in each case.

Thibault Lejeune, Daniel Schaerer

We have used an updated version of the empirically and semi-empirically calibrated BaSeL library of synthetic stellar spectra of Lejeune et al. (1997, 1998) and Westera et al. (1999) to calculate synthetic photometry in the UBVRIJHKLL'M, HST-WFPC2, Geneva, and Washington systems for the entire set of non-rotating Geneva stellar evolution models covering

Denis Puy

Primordial chemistry began, at the recombination epoch, when the adiabatic expansion caused the temperature of the radiation to fall below 4000K. The chemistry of the early Universe involves the elements hydrogen, its isotope deuterium, helium with its isotopic forms and lithium. In this contribution I will discuss the influence of the primordial molecules o

Martin White

We discuss the different definitions of the mass of a halo in common use and how one may convert between them. Using N-body simulations we show that mass estimates based on spherical averages are much more tightly correlated with each other than with masses based on the number of particles in a halo. The mass functions pertaining to some different mass defin

J. H. Swank

Low frequency (approximately 0.1-35 Hz) quasi-periodic oscillations (QPO) of the X-ray flux characterize many of the black hole candidates, in particular those which have radio evidence for jets. These QPO have amplitudes of up to 20 per cent in the states of black hole novae which are called very high and intermediate. The frequencies are correlated with th

Eric F. Bell, Roelof S. de Jong

We have used a suite of simplified spectrophotometric spiral galaxy evolution models to argue that there are substantial variations in stellar mass-to-light ratios (M/Ls) within and among galaxies, amounting to factors of between 3 and 7 in the optical, and factors of 2 in the near-infrared. Under the assumption of a universal spiral galaxy IMF, our models s

D. Barrado y Navascués, John R. Stauffer, César Briceño, Brian Patten

We have identified a large sample of probable low mass members of the young open cluster IC2391 based on optical (VRIZ) and Infrared (JHK$_s$) photometry. Our sample includes 50 probable members and 82 possible members, both very low mass stars and brown dwarfs. We also provide accurate positions for these stars and brown dwarf candidates derived from red UK

T. C. Beers, S. Rossi, D. O'Donoghue, D. Kilkenny

The Edinburgh-Cape Blue Object Survey is an ongoing project to identify and analyse a large sample of hot stars selected initially on the basis of photographic colours (down to a magnitude limit B~18.0) over the entire high-Galactic-latitude southern sky, then studied with broadband UBV photometry and medium-resolution spectroscopy. Due to unavoidable errors

M. Ave, R. A. Vazquez, E. Zas

We present a framework for the study of muon density patterns on the ground due to showers produced in the atmosphere by cosmic rays incident at high zenith angles. As a checking procedure predictions of a model based on such a framework are compared to simulation results.

D. Steeghs, K. O'Brien, K. Horne, R. Gomer

We have detected coherent oscillations, at multiple frequencies, in the line and continuum emission of the eclipsing dwarf nova V2051 Ophiuchi using the 10m Keck II telescope. Our own novel data acquisition system allowed us to obtain very fast spectroscopy using a continuous readout of the CCD on the LRIS spectrograph. This is the first time that dwarf nova

Kouichi Hirotani, Shinpei Shibata

We investigate a stationary pair production cascade in the outer magnetosphere of a spinning neutron star. The charge depletion due to a global current, causes a large electric field along the magnetic field lines. Migratory electrons and/or positrons are accelerated by this field to radiate curvature gamma-rays, some of which collide with the X-rays to mate

K. J. van der Heyden, F. Paerels, J. Cottam, J. S. Kaastra

We present X-ray observations of PSR 0540-69.3 with the XMM-Newton observatory. The spectra obtained with the Reflection Grating Spectrometer reveal, for the first time, emission from ionized species of O, Ne and Fe originating from the SNR shell. Analysis of the emission line spectrum allows us to derive estimates of the temperature, ionization timescale, a

Andrea Lorenzani, Francesco Palla

We present the initial results of a study aimed at computing the global effects of the X-ray ionization due to young stars within a molecular cloud that forms stars with a standard IMF at a rate accelerating with time. We model the gas distribution of the cloud as a fractal of dimension 2.3. We introduce the concept of a "Roentgen sphere" as the regi

F. Favata

The ``current wisdom'' regarding the structuring of the X-ray emitting corona in active stars (i.e. a corona dominated by extended coronal structures) is briefly reviewed, followed by a review of a new approach to flare analysis and the analysis of a significant number of newly observed and previously published large flares, all leading to a much mor

HEGRA Collaboration, F. Aharonian

Data taken with the HEGRA system of imaging atmospheric Cherenkov telescopes during the 1997 flares of Mkn 501 are reanalyzed using an algorithm providing improved energy resolution. A resolution of 10% to 12% is obtained by accounting for the variation of the Cherenkov light yield with the height of the shower maximum in the atmosphere. The improved energy

Nagasawa Michiyasu

Primordial black hole formation by cosmic string collapse is reconsidered when the winding number of the string is larger than the unity. The line energy density of the multiple winding string becomes greater than that of the single winding string so that the probability of the black hole formation by the string collapse during the loop oscillation would be

Taihei Yano, Masashi Chiba, Naoteru Gouda

We present a method, based on the kinematic analysis of the Galactic disk stars, to clarify whether the internal motions of the stellar system in spiral arms follow those expected in the density wave theory. The method relies on the comparison with the linear relation between the phases of spatial positions and epicyclic motions of stars, as drawn from the t

Daniele Fargion

Weak isolated X-ray precursor events before the main Gamma Ray Burst, GRB, and also rare Soft Gamma Repeaters, SGR, events are in disagreement with any Fireball, or Magnetar, scenarios. These models are originated by an unique explosive event leading, by internal-external shock waves, to softer secondary trains following a main gamma signals. Indeed the earl

Robert L. Oldershaw

Mass functions for samples of white dwarf stars and for a large heterogeneous sample of nearby stars appear to have unexplained deficits in the range of 0.70 to 0.75 Solar Masses. The existence, or non-existence, of this anomaly constitutes a definitive test of a fractal cosmological model that inherently predicts a gap in stellar mass functions at about 0.7

J. Daniel Christensen, Mark Hovey

An important example of a model category is the category of unbounded chain complexes of R-modules, which has as its homotopy category the derived category of the ring R. This example shows that traditional homological algebra is encompassed by Quillen's homotopical algebra. The goal of this paper is to show that more general forms of homological algebra

M. Alimohammadi, H. Mohseni Sadjadi

Using a covariant method to regularize the composite operators, we obtain the bosonized action of the massive Schwinger model on a classical curved background. Using the solution of the bosonic effective action, the energy of two static external charges with finite and large distance separation on a static curved space-time is obtained. The confining behavio

J. Saavedra, R. Troncoso, J. Zanelli

Dynamical systems whose symplectic structure degenerates, becoming noninvertible at some points along the orbits are analyzed. It is shown that for systems with a finite number of degrees of freedom, like in classical mechanics, the degeneracy occurs on domain walls that divide phase space into nonoverlapping regions each one describing a nondegenerate syste

K. Miyagawa, H. Yamamura, T. Mart, C. Bennhold

Photo- and electroproduction processes of K+ on the deuteron are investigated theoretically. Modern hyperon-nucleon forces as well as an updated kaon production operator on the nucleon are used. Sizable effects of the hyperon-nucleon final state interaction are seen in various observables. Especially the photoproduction double polarization observable C_z is

Heather Russell

For an arbitrary field K, let I be an ideal in the ring K[[x,y]] expressible as a polynomial in either the pair of ideals (x, y^4) and (x,y) or the pair (x,y^3) and (x^2, y). Let G be the group of automorphisms of K[[x,y]] sending the ideal (x,y^2) to itself. Then the normalization of the closure of the G orbit of I is a toric variety. We use the interplay o

Eduardo Cattani, Javier Fernandez

Assuming suitable convergence properties for the Gromov-Witten potential of a Calabi-Yau manifold $X$ one may construct a polarized variation of Hodge structure over the complexified Kähler cone of $X$. In this paper we show that, in the case of fourfolds, there is a correspondence between ``quantum potentials'' and polarized variations of Hodge stru

Shlomo Gelaki

A fundamental problem in the theory of Hopf algebras is the classification and explicit construction of finite-dimensional quasitriangular Hopf algebras over C. These Hopf algebras constitute a very important class of Hopf algebras, introduced by Drinfeld (e.g. the quantum double of a Hopf algebra). However, this intriguing problem turns out to be extremely

Kostas. D. Kokkotas, Johannes Ruoff

We present a new survey of the radial oscillation modes of neutron stars. This study complements and corrects earlier studies of radial oscillations. We present an extensive list of frequencies for the most common equations of state and some more recent ones. In order to check the accuracy, we use two different numerical schemes which yield the same results.

D. Behnke, D. Blaschke, V. Pervushin, D. Proskurin

We consider cosmological consequences of a conformal-invariant unified theory which is dynamically equivalent to general relativity and is given in a space with the geometry of similarity. We show that the conformal-invariant theory offers new explanations for to such problems as the arrow of time, initial cosmic data, dark matter and accelerating evolution

J. R. Anglin, P. Drummond, A. Smerzi

The quantum Josephson Hamiltonian of two weakly linked Bose-Einstein condensates is written in an overcomplete phase representation, thus avoiding the problem of defining a Hermitian phase operator. We discuss the limit of validity of the standard, non-rigorous Mathieu equation, due to the onset of a higher order $\cos 2 ϕ$ term in the Josephson potential, a

Davide Controzzi, Fabian H. L. Essler, Alexei M. Tsvelik

At low energies the charge sector of one dimensional Mott insulators can be described in terms of a quantum Sine-Gordon model. Using exact results derived from integrability it is possible to determine dynamical properties like the frequency dependent optical conductivity. We compare the exact results to perturbation theory and renormalisation group calculat

G. Haran, A. D. S. Nagi

We present a theory of combined nonmagnetic and magnetic impurity scattering in anisotropic superconductors accounting for the momentum-dependent impurity potential. Applying the model to the d-wave superconducting state, we obtain a quantitative agreement with the initial suppression of the critical temperature due to Zn and Ni substitutions as well as elec

Eric J. Friedman

This paper has been withdrawn by the author, since one of the key results duplicates existing work, as pointed out by a reader. I am currently revising the manuscript.

Andrew W. Blain

Deep submillimetre(submm)-wave surveys made over the last three years using the SCUBA camera at the 15-m James Clerk Maxwell Telescope (JCMT) have revealed a new population of very luminous high-redshift galaxies. The properties of this population, and their contribution to the intensity of the extragalactic background radiation field are described briefly,

Brad K. Gibson, Peter B. Stetson

Based upon multi-epoch Hubble Space Telescope observations, we present the discovery of sixteen high-quality Cepheid candidates in NGC 4527. Corrected for metallicity effects in the Cepheid period-luminosity relation, we derive a distance, including both random (r) and systematic (s) uncertainties, of 13.0+/-0.5(r)+/-1.2(s) Mpc. Our result is then used to pr

Joel R. Primack, Rachel S. Somerville, James S. Bullock, Julien E. G. Devriendt

We discuss how measurements of the absorption of $γ$-rays from GeV to TeV energies via pair production on the extragalactic background light (EBL) can probe important issues in galaxy formation. We use semi-analytic models (SAMs) of galaxy formation, set within the hierarchical structure formation scenario, to obtain predictions of the EBL for 0.1-1000$μ$m.

Riccardo Barbieri, Lawrence J. Hall, Yasunori Nomura

A SU(3) \times SU(2) \times U(1) supersymmetric theory is constructed with a TeV sized extra dimension compactified on the orbifold S^1/(Z_2 \times Z_2'). The compactification breaks supersymmetry leaving a set of zero modes which correspond precisely to the states of the 1 Higgs doublet standard model. Supersymmetric Yukawa interactions are localized at

Sebastian de Haro, Kostas Skenderis, Sergey N. Solodukhin

We study gravitational aspects of Brane-World scenarios. We show that the bulk Einstein equations together with the junction condition imply that the induced metric on the brane satisfies the full non-linear Einstein equations with a specific effective stress energy tensor. This result holds for any value of the bulk cosmological constant. The analysis is do

Kentaro Nagamine, Masataka Fukugita, Renyue Cen, Jeremiah P. Ostriker

We study star formation history and stellar metallicity distribution in galaxies in a Lambda cold dark matter universe using a hydrodynamic cosmological simulation. Our model predicts star formation rate declining in time exponentially from an early epoch to the present with the time-scale of 6 Gyr, which is consistent with the empirical Madau plot with mode

A. S. Alexandrov, Guo-meng Zhao, H. Keller, B. Lorenz

The modern multi-polaron theory predicts a polaronic Fermi-liquid state, but such a state has not been unambigously confirmed by experiment so far. Here we report theoretical and experimental studies of the isotope effects on the low temperature kinetic properties of the doped ferromagnetic manganites. Our results provide clear evidence for a novel polaronic

A. V. Belitsky, D. Müller, A. Kirchner, A. Schäfer

We study twist-three effects in spin, charge, and azimuthal asymmetries in deeply virtual Compton scattering on a spin-zero target. Contributions which are power suppressed in 1/Q generate a new azimuthal angle dependence of the cross section which is not present in the leading twist results. On the other hand the leading twist terms are not modified by the

Ambar Jain, Pankaj Jain, Douglas W. McKay, John P. Ralston

In models based on large extra dimensions where massive spin 2 exchange can dominate at high energies, the neutrino-proton cross section can rise to typical hadronic values at energies above 10^20 eV. The neutrino then becomes a candidate for the primary that initiates the highest energy cosmic ray showers. We investigate characteristics of neutrino-induced

Wei-Guo Yin, Hai-Qing Lin, Chang-De Gong

By use of the orbital t-J model, we calculate the photoemission spectra of LaMnO3 using the exact diagonalization technique, and interpret our numerics quite well in the orbital-polaron scenario where the scattering between holes and orbital excitations is treated within the self-consistent Born approximation. The quasiparticle bandwidth is found to be of th

Paolo Padoan, AAke Nordlund

The morphology and kinematics of molecular clouds (MCs) are best explained as the consequence of super--sonic turbulence. Super--sonic turbulence fragments MCs into dense sheets, filaments and cores and large low density ``voids'', via the action of highly radiative shocks. We refer to this process as "turbulent fragmentation". In this work w

Craig A. Tracy, Harold Widom

We prove that the distribution function of the largest eigenvalue in the Gaussian Unitary Ensemble (GUE) in the edge scaling limit is expressible in terms of Painlevé II. Our goal is to concentrate on this important example of the connection between random matrix theory and integrable systems, and in so doing to introduce the newcomer to the subject as a who

Andrei Khrennikov

We demonstrate the quantum probabilistic rule (which differ from classical Bayes' formula by the cosinus factor) can be obtained on purely classical basis as a consequence of the perturbation effect of preparation procedures. In any case the interference can be easily simulated for macrosystems. Moreover, we obtain the classification of all possible tran

Thomas Curtright

We discuss elementary entwiners that cross-weave the variables of certain integrable models: Liouville, sine-Gordon, and sinh-Gordon field theories in two-dimensional spacetime, and their quantum mechanical reductions. First we define a complex time parameter that varies from one energy-shell to another. Then we explain how field propagators can be simply ex

R. Ibragimov, Sh. Sharakhmetov, A. Cecen

The present paper concentrates on the analogues of Rosenthal's inequalities for ordinary and decoupled bilinear forms in symmetric random variables. More specifically, we prove the exact moment inequalities for these objects in terms of moments of their individual components. As a corollary of these results we obtain the explicit expressions for the best

T. Wedhorn

This work is intended as an introduction to the statement and the construction of the local Langlands correspondence for GL(n) over p-adic fields. The emphasis lies on the statement and the explanation of the correspondence.

Ioannis P. Zois

We try to give a qualitative description of the Godbillon-Vey class and its relation on the one hand to the holonomy and on the other hand to the topological entropy of a foliation, using a remarkable theorem proved recently by G. Duminy (which still remains unpublished), relating these three notions in the case of codim-1 foliations. Moreover we shall inves

Jose D. Edelstein, Marta Gomez-Reino, Marcos Marino

We investigate some aspects of N=2 twisted theories with matter hypermultiplets in the fundamental representation of the gauge group. A consistent formulation of these theories on a general four-manifold requires turning on a particular magnetic flux, which we write down explicitly in the case of SU(2k). We obtain the blowup formula and show that the blowup

A. V. Kotikov

We discuss a progress in calculation of Feynman integrals which has been done with help of the differential equation method and demonstrate the results for a class of two-point two-loop diagrams.

A. Ya. Berdnikov, Ya. A. Berdnikov, A. N. Ivanov, V. F. Kosmach

The cross sections for the reactions of the strange production p + p -> p + Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds of the final states p Lambda K^+ and p Sigma^0 K^+ are calculated in the effective Lagrangian approach. Our approach is based on the dominant contribution of the one-pion exchange and strong interaction of the colliding prot

Achille Corsetti, Pran Nath

A brief review is given of some of the recent developments in the theoretical analyses of supersymmetric dark matter. These include the effects of uncertainties in the wimp velocity and wimp density and of the effects of uncertainties in the quark densities of the proton. Also analyzed are the effects of non-universalities in the gaugino sector and their eff

Hyun-Chul Kim, Michal Praszalowicz, Klaus Goeke

We present the recent investigation on the effect of the SU(3) symmetry breaking in the spin structure of the octet baryons.

Vladimir S. Mashkevich

Singularity theorems of general relativity utilize the notion of causal geodesic incompleteness as a criterion of the presence of a spacetime singularity. The incompleteness of a causal curve implies the end and/or beginning of the existence of a particle, which is an event. In the commonly accepted approach, singularities are not incorporated into spacetime

N. S. Averkiev, L. E. Golub, M. Willander

Electron spin relaxation caused by the D'yakonov-Perel' mechanism is investigated theoretically in asymmetrical A$_3$B$_5$ heterostructures. The total spin relaxation anisotropy is demonstrated for a wide range of structure parameters and temperatures. The spin relaxation rates dependences are derived for GaAs-based heterojunction and triangular quan

V. A. Gritsenko, Yu. N. Morokov, Yu. N. Novikov, J. B. Xu

The dominant dielectric used currently in silicon devices is silicon oxide. Its application for future devices will be impeded by several fundamental limitations which lead to low reliability of semiconductor devices and to the necessity of alternative dielectrics. Amorphous silicon nitride and oxynitride are considered now as alternative to silicon oxide in

A. Zoroddu, F. Bernardini, P. Ruggerone, V. Fiorentini

A number of diverse bulk properties of the zincblende and wurtzite III-V nitrides AlN, GaN, and InN, are predicted from first principles within density functional theory using the plane-wave ultrasoft pseudopotential method, within both the LDA (local density) and GGA (generalized gradient) approximations to the exchange-correlation functional. Besides struc

L. Teodoro

We perform a detailed comparison of the IRAS PSCz and 1.2-Jy spherical harmonic coefficients of the predicted velocity fields in redshift space. The monopole terms predicted from the two surveys show some differences. Faint galaxies are responsible for this mismatch that disappears when extracting a PSCz subsample of galaxies with fluxes larger than 1.2 Jy.

Sandra Savaglio

According to Pei, Fall & Hauser (1999), the global metallicity evolution of the Universe can be represented by the ratio of the total metal content to the total gas content measured in Damped Lyman-alpha (DLA) systems (the ``column density weighted metallicity'' `a la Pettini). To minimize dust obscuration effects, a DLA sample with negligible dust c

S. Masi, P. A. R. Ade, J. Bock, A. Boscaleri

We present a preliminary analysis of the BOOMERanG LDB maps, focused on foregrounds. BOOMERanG detects dust emission at moderately low galactic latitudes ($b > -20^o$) in bands centered at 90, 150, 240, 410 GHz. At higher Galactic latitudes, we use the BOOMERanG data to set conservative upper limits on the level of contamination at 90 and 150 GHz. We find th

S. A. Levshakov, P. Molaro, M. Centurion, S. D'Odorico

New results from the search for H2 absorption in the damped Ly-alpha galaxy at redshift z = 3.4 toward QSO 0000-2620 (z_em = 4.1) are reported. The high-resolution (lambda/Delta lambda = 48,000) spectra of Q0000-2620 were obtained using the Ultraviolet - Visual Echelle Spectrograph (UVES) on the 8.2m ESO Kueyen telescope. The ortho-H2 column density is found

P. de Bernardis, P. A. R. Ade, J. J. Bock, J. R. Bond

We report the first results from the BOOMERanG experiment, which mapped at 90, 150, 240 and 410 GHz a wide (3%) region of the microwave sky with minimal local contamination. From the data of the best 150 GHz detector we find evidence for a well defined peak in the power spectrum of temperature fluctuations of the Cosmic Microwave Background, localized at $\e

P. de Bernardis, P. A. R. Ade, J. J. Bock, J. R. Bond

BOOMERanG has recently resolved structures on the last scattering surface at redshift $\sim$ 1100 with high signal to noise ratio. We review the technical advances which made this possible, and we focus on the current results for maps and power spectra, with special attention to the determination of the total mass-energy density in the Universe and of other

Yasuhiro Shioya, Neil Trentham, Yoshiaki Taniguchi

We construct a starburst model for the hidden starbursts in Arp 220 based on the new Starburst99 models of Leitherer et al. Comparing these stellar population synthesis models with observations, we show that the hidden power source must be due to star formation (as opposed to an AGN) at the 50% level or more in order to avoid an ionizing photon excess proble

Gary Gibbons, Renata Kallosh, Andrei Linde

A set of consistency conditions is derived from Einstein equations for brane world scenarios with a spatially periodic internal space. In particular, the sum of the total tension of the flat branes and the non-negative integral of the gradient energy of the bulk scalars must vanish. This constraint allows us to make a simple consistency check of several mode

S. P. de Alwis, A. T. Flournoy

We investigate and interpret a large class of soliton solutions found in noncommutative tachyon condensation. These constructions make extensive use of the idea that Dp-branes may be built out of lower dimensional branes. Finally we comment on a recently proposed solution generating technique.

Riccardo Barbieri, Alessandro Strumia

Continuing previous work, a model independent analysis of the solar neutrino anomaly is performed in terms of neutrino oscillations, allowing a comparison with the predictions of the Standard Solar Model. SMA and LMA solutions emerge also in this case, although somewhat different from the standard ones. The significance of the NC/CC double ratio measurable i

E. Cuevas, V. Gasparian, M. Ortuno

We investigate numerically the power-law random matrix ensembles. Wavefunctions are fractal up to a characteristic length whose logarithm diverges asymmetrically with different exponents, 1 in the localized phase and 0.5 in the extended phase. The characteristic length is so anomalously large that for macroscopic samples there exists a finite critical region

Kaiki Taro Inoue

In this paper, the cosmic microwave background (CMB) anisotropy in a multiply-connected compact flat 3-torus model with the cosmological constant is investigated. Using the COBE-DMR 4-year data, a full Bayesian analysis revealed that the constraint on the topology of the flat 3-torus model with low-matter-density is less stringent. As in compact hyperbolic m

M. I. Gorenstein

Two signatures of the quark-gluon plasma -- strangeness `enhancement' and $J/ψ$ `suppression' -- in nucleus--nucleus collisions at the SPS energies are critically discussed.

J. Fiurasek, U. Leonhardt, R. Parentani

Slow light in moving media reaches a paradoxical regime when the flow speed of the medium approaches the group velocity of light. Pulses can penetrate a region where a counter-propagating flow exceeds the group velocity. When the counter-flow slows down pulses are reflected.

Tim Roemer

We study the x- and y-regularity of a bigraded K-algebra R. These notions are used to study asymptotic properties of certain finitely generated bigraded modules. As an application we get for any equigenerated graded ideal I upper bounds for the number j_0 for which reg(I^j) is a linear function for j >= j_0. Finally we give upper bounds for the x- and y-regu

Valentin V. Khoze, Gabriele Travaglini

Using background field perturbation theory we study Wilsonian effective actions of noncommutative gauge theories with an arbitrary matter content. We determine the Wilsonian coupling constant and the gauge boson polarization tensor as functions of the momentum scale k at the one-loop level and study their short-distance behaviour as theta k ->0, where theta

A. Crépieux, P. Bruno

We present a weak-relativistic limit comparison between the Kohn-Sham-Dirac equation and its approximate form containing the exchange coupling, which is used in almost all relativistic codes of density-functional theory. For these two descriptions, an exact expression of the Dirac Green's function in terms of the non-relativistic Green's function is

F. S. Bergeret, A. F. Volkov, K. B. Efetov

We analyze the proximity effect in a superconductor/ferromagnet (S/F) structure with a local inhomogeneity of the magnetization in the ferromagnet near the S/F interface. We demonstrate that not only the singlet but also the triplet component of the superconducting condensate is induced in the ferromagnet due to the proximity effect. Although the singlet com

Tomoya Isoshima, Kazushige Machida, Tetsuo Ohmi

Quantum vortices in the multi-component Bose-Einstein condensation (BEC) are investigated theoretically. It is found that three kinds of the vortex configurations are possible and their physical properties are discussed in details, including the density distribution and the spin texture. By using the Bogoliubov theory extended to the three component BEC, the

Enrique Alvarez, Juan Jose Manjarin

The static gauge potential between heavy sources is computed from a recently introduced non-critical bosonic string background. When the sources are located at the infinity of the holographic coordinate, the linear dilaton behavior is recovered, which means that the potential is exactly linear in the separation between the sources. When the sources are moved

Mohan Narayan, S. Uma Sankar

Recently it is advocated that high intensity and low energy $(E_ν\sim 2 GeV)$ neutrino beams should be built to probe the $(13)$ mixing angle $ϕ$ to a level of a few parts in $10^4$. Experiments using such beams will have better signal to background ratio in searches for $ν_μ\to ν_e$ oscillations. We propose that such experiments can also determine the sign

Klaus Morawetz

An exact correspondence is established between a $N$-body classical interacting system and a $N-1$-body quantum system with respect to the partition function. The resulting quantum-potential is a $N-1$-body one. Inversely the Kelbg potential is reproduced which describes quantum systems at a quasi-classical level. The found correspondence between classical a

L. Moriconi, F. A. S. Nobre

We study probability density functions (pdfs) of the circulation of velocity and magnetic fields in magnetohydrodynamics, computed for a circular contour within inertial range scales. The analysis is based on the instanton method as adapted to the Martin-Siggia-Rose field theory formalism. While in the viscous limit the expected gaussian behaviour of fluctua

M. H. S. Amin, A. N. Omelyanchouk, A. M. Zagoskin

A boundary between two d-wave superconductors or an s-wave and a d-wave superconductor generally breaks time-reversal symmetry and can generate spontaneous currents due to proximity effect. On the other hand, surfaces and interfaces in d-wave superconductors can produce localized current-carrying states by supporting the T-breaking combination of dominant an

J. J. Halliwell

This paper explores the possibility that an exactly decoherent set of histories may be constructed from an approximately decoherent set by small distortions of the operators characterizing the histories. In particular, for the case of histories of positions and momenta, this is achieved by doubling the set of operators and then finding, amongst this enlarged

Wolf von Klitzing, Romain Long, Vladimir S. Ilchenko, Jean Hare

We have tuned the whispering gallery modes of a fused silica micro- resonator over nearly 1 nm at 800 nm, i.e.over half of a free spectral range or the equivalent of 10^6 linewidths of the resonator.This has been achieved by a new method based on the stretching of a two-stem microsphere.The devices described below will permit new Cavity-QED experiments with

F. Barra, P. Gaspard

We derive a formula for the level spacing probability distribution in quantum graphs. We apply it to simple examples and we discuss its relation with previous work and its possible application in more general cases. Moreover, we derive an exact and explicit formula for the level spacing distribution of integrable quantum graphs.

Akos Dobay, Pierre-Edouard Sottas, Jacques Dubochet, Andrzej Stasiak

In thermally fluctuating long linear polymeric chain in solution, the ends come from time to time into a direct contact or a close vicinity of each other. At such an instance, the chain can be regarded as a closed one and thus will form a knot or rather a virtual knot. Several earlier studies of random knotting demonstrated that simpler knots show their high

E. A. Kolganova, A. K. Motovilov, Y. K. Ho

In this work we compare two different approaches to calculation of the three-body resonances on the basis of Faddeev differential equations. The first one is the complex scaling approach. The second method is based on an immediate calculation of resonances as zeros of the three-body scattering matrix continued to the physical sheet.

U. Lombardo, P. Schuck

It is shown within the strong-coupling BCS approach that, starting from the zero-density limit of superfluid nuclear matter, with increasing density deuterons first shrink before they start expanding.

F. A. Danevich, V. V. Kobychev, O. A. Ponkratenko, V. I. Tretyak

The double beta decay study of 160-Gd has been performed in the Solotvina Underground Laboratory with the help of Gd_2SiO_5(Ce) crystal scintillator (volume 95 cc). The background of the detector in the vicinity of the 2 beta energy of 160-Gd was reduced to 1.0 cpd/keV kg. The new improved half-life limits have been established for neutrinoless 2 beta decay

P. Muruganandam, M. Lakshmanan, S. Parthasarathy

The conditions for synchronization in unidirectionally coupled chaotic oscillators are revisited. We demonstrate with typical examples that the conditional Lyapunov exponents (CLEs) play an important role in distinguishing between intermittent and permanent synchronizations, when the analytic conditions for chaos synchronization are not uniformly obeyed. We

A. V. Penskoi

The Volterra lattice is considered. New gradient interpretation for this dynamical system is proposed. This interpretation seems to be more natural than existing ones.

A. P. Veselov, A. V. Penskoi

A generalization of the theory of algebro-geometric Poisson brackets on the space of finite-gap Schroedinger operators, developped by S. P. Novikov and A. P. Veselov, to the case of periodic zero-diagonal difference operators of second order is proposed. A necessary and sufficient condition for such a bracket to be compatible with higher Volterra flows is fo

Morihiko Saito

We give a formalism of arithmetic mixed sheaves including the case of arithmetic mixed Hodge structures, and show the nonvanishing of certain higher extension groups, and also the nontriviality of the second Abel-Jacobi map for zero cycles on a smooth proper complex variety of any dimension under the existence of a nontrivial global two-form. For two codimen

Heather Russell

We study correspondences of zero-dimensional subschemes of a smooth variety X "aligned" in the same way in inside the appropriate product of Hilbert schemes. We show that such correspondences have etale covering by other such correspondences that are affine bundles over flag bundles on the tangent bundle of X. Moreover, we show that for many such cov

K. C. H. Mackenzie

We define an abstract notion of double Lie algebroid, which includes as particular cases: (1) the double Lie algebroid of a double Lie groupoid in the sense of the author, such as the iterated tangent bundle of an ordinary manifold, and various iterated tangent/cotangent constructions in symplectic and Poisson geometry; (2) the double of a Lie bialgebra; (3)

J. Y. Abuhlail, J. Gomez-Torrecillas, F. J. Lobillo

Let $A$ be an algebra over a commutative ring $R$. If $R$ is noetherian and $A^\circ$ is pure in $R^A$, then the categories of rational left $A$-modules and right $A^\circ$-comodules are isomorphic. In the Hopf algebra case, we can also strengthen the Blattner-Montgomery duality theorem. Finally, we give sufficient conditions to get the purity of $A^\circ$ i