February 2002 arXiv papers — page 10

G. Ghisellini, A. Celotti, L. Costamante

The spectral properties of blazars seem to follow a phenomenological sequence according to the source luminosity. By inferring the source physical parameters through (necessarily) modeling the blazar spectra, we have previously proposed that the sequence arises because the particles responsible for most of the emission suffer increasing radiative losses as t

Naoki Seto

The binary confusion noise spectrum at LISA band depends strongly on observational period and abundance of Galactic close white dwarf binaries (CWDBs). We have investigated how the number of the resolved Galactic CWDBs varies with operation period of LISA, and found that the resolved number would typically grows by a factor of 5 when the operation period inc

Jun Ma, Xu Zhou, Jiansheng Chen, Hong Wu

In this third paper of our series, we present CCD spectrophotometry of 78 star clusters that were detected by Chandar, Bianchi, & Ford in the nearby spiral galaxy M33. CCD images of M33 were obtained as a part of the BATC Color Survey of the sky in 13 intermediate-band filters from 3800 to 10000Å. By aperture photometry, we obtain the spectral energy distrib

A. D. Gromko, A. V. Fedorov, Y. -D. Chuang, J. D. Koralek

Using high-resolution angle-resolved photoemission spectroscopy on $Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}$, we have made the first observation of a mass renormalization or "kink" in the E vs. $\vec k$ dispersion relation localized near $(π, 0)$. Compared to the kink observed along the nodal direction, this new effect is clearly stronger, appears at a lower ene

Brian Berkowitz, Joseph Klafter, Ralf Metzler, Harvey Scher

The basic conceptual picture and theoretical basis for development of transport equations in porous media are examined. The general form of the governing equations is derived for conservative chemical transport in heterogeneous geological formations, for single realizations and for ensemble averages of the domain. The application of these transport equations

J. C. A. Barata, D. A. Cortez

In this paper we study the time evolution of a class of two-level systems driven by periodic fields in terms of new convergent perturbative expansions for the associated propagator U(t). The main virtue of these expansions is that they do not contain secular terms, leading to a very convenient method for quantitatively studying the long-time behaviour of tha

Zheng Zheng, Jeremy L. Tinker, David H. Weinberg, Andreas A. Berlind

Using cosmological N-body simulations, we investigate the influence of the matter density parameter Omega_m and the linear theory power spectrum P(k) on statistical properties of the dark matter halo population -- the mass function n(M), the halo correlation function, and halo pairwise velocity statistics. For fixed P(k), the effect of changing Omega_m is si

Pirin Erdogdu, Stefano Ettori, Ofer Lahav

We use a generalised procedure for the combined likelihood analysis of different cosmological probes, the `Hyper-Parameters' method, that allows freedom in the relative weights of the raw measurements. We perform a joint analysis of the cepheid-calibrated data from the Hubble Space Telescope Key Project and the baryon mass fraction in clusters to constra

G. Gervais, K. Yawata, N. Mulders, W. P. Halperin

The phase diagram of the superfluid phases of $^{3}$He in 98% aerogel was determined in the range of pressure from 15 to 33 bars and for fields up to 3 kG using high-frequency sound. The superfluid transition in aerogel at 33.4 bars is field independent from 0 to 5 kG and shows no evidence of an $A_{1}-A_{2}$ splitting. The first-order transition between the

Ralph Blumenhagen, Boris Kors, Dieter Lust, Tassilo Ott

Non-supersymmetric brane world scenarios in string theory display perturbative instabilities that usually involve run-away potentials for scalar moduli fields. We investigate in the framework of intersecting brane worlds whether the leading order scalar potential for the closed string moduli allows to satisfy the slow-rolling conditions required for applicat

Naoki Yoshida, Felix Stoehr, Volker Springel, Simon D. M. White

We compare two techniques for following the cooling of gas and its condensation into galaxies within high resolution simulations of cosmologically representative regions. Both techniques treat the dark matter using N-body methods. One follows the gas using smoothed particle hydrodynamics (SPH) while the other uses simplified recipes from semi-analytic (SA) m

Ivica Zerec, Alexander Yaresko, Peter Thalmeier, Yuri Grin

Electronic band structures for Ba$_{6}$Ge$_{25}$ and Ba$_{4}$Na$_{2}$Ge$_{25}$ clathrates are calculated using linear muffin-tin orbital method within the local density approximation. It is found that barium states strongly contribute to the density of states at the Fermi level and thus can influence the transport properties of the compounds. A sharp peak of

P. A. Grassi, G. Policastro, P. van Nieuwenhuizen

We obtain the correct cohomology at any ghost number for the open and closed covariant superstring, quantized by an approach which we recently developed. We define physical states by the usual condition of BRST invariance and a new condition involving a new current which is related to a grading of the underlying affine Lie algebra.

Chris Dewdney, George Horton

We show that quantum mechanics can be given a Lorentz-invariant realistic interpretation by applying our recently proposed relativistic extension of the de Broglie-Bohm theory to deduce non-locally correlated, Lorentz-invariant individual particle motions for the Einstein-Podolsky-Rosen experiment and the double-interferometer experiment proposed by Horne, S

Ronald Fintushel, Jongil Park, Ronald J. Stern

We present constructions of simply connected symplectic 4-manifolds which have (up to sign) one basic class and which fill up the geographical region between the half-Noether and Noether lines.

Avishay Gal-Yam, Eran O. Ofek, Alexei V. Filippenko, Ryan Chornock

The optically variable source SDSS J124602.54+011318.8 first appears in Sloan Digital Sky Survey (SDSS) data as a bright point source with nonstellar colors. Subsequent SDSS imaging and spectroscopy showed that the point source declined or disappeared, revealing an underlying host galaxy at redshift 0.385. Based on these properties, the source was suggested

N. Riazi, A. Azizi, S. M. Zebarjad

A system of coupled scalar fields is introduced which possesses a spectrum of massive single-soliton solutions. Some of these solutions are unstable and decay into lower mass stable solitons. Some properties of the solutions are obtained using general principles including conservations of energy and topological charges. Rest energies are calculated via a var

Jaromir Fiurasek

We study the Braunstein-Kimble setup for teleportation of quantum state of a single mode of optical field. We assume that the sender and receiver share a two-mode Gaussian state and we identify optimum local Gaussian operations that maximize the teleportation fidelity. We consider fidelity of teleportation of pure Gaussian states and we also introduce fideli

Pavel Grozman, Dimitry Leites, Irina Shchepochkina

Here we continue to list the differential operators invariant with respect to the 15 exceptional simple Lie superalgebras of polynomial vector fields. A part of the list (for operators acting on tensors with finite dimensional fibers) was earlier obtained in 2 of the 15 cases by Kochetkov and in one more instance by Kac and Rudakov. Broadhurst and Kac conjec

Mario Basletic, Bojana Korin-Hamzic, Kazumi Maki

The presence of subphases in spin-density wave (SDW) phase of (TMTSF)2PF6 below T* ~ 4K has been suggested by several experiments but the nature of the new phase is still controversial. We have investigated the temperature dependence of the angular dependence of the magnetoresistance in the SDW phase which shows different features for temperatures above and

J. L. Jaramillo, V. Aldaya

We propose a scenario for particle-mass generation, assuming the existence of a physical regime where, firstly, physical particles can be considered as point-like objects moving in a background space-time and, secondly, their mere presence spoils the invariance under the local diffeomorphism group, resulting in an anomalous realization of the latter. Under t

Olav F. Syljuasen, Anders W. Sandvik

We introduce the concept of directed loops in stochastic series expansion and path integral quantum Monte Carlo methods. Using the detailed balance rules for directed loops, we show that it is possible to smoothly connect generally applicable simulation schemes (in which it is necessary to include back-tracking processes in the loop construction) to more res

Laura Tolos, Angels Ramos, Artur Polls

The antikaon optical potential in hot and dense nuclear matter is studied within the framework of a coupled-channel self-consistent calculation taking, as bare meson-baryon interaction, the meson-exchange potential of the Jülich group. Typical conditions found in heavy-ion collisions at GSI are explored. As in the case of zero temperature, the angular moment

Gebhard Gruebl, Raimund Moser, Klaus Rheinberger

We compute the Bohmian trajectories of the incoming scattering plane waves for Klein's potential step in explicit form. For finite norm incoming scattering solutions we derive their asymptotic space-time localization and we compute some Bohmian trajectories numerically. The paradox, which appears in the traditional treatments of the problem based on the

Frank E. Close, Qiang Zhao

We show how quark-hadron duality can emerge for valence spin averaged structure functions, and for the non-forward distributions of Deeply Virtual Compton Scattering. Novel factorisations of the non-forward amplitudes are proposed. Some implications for large angle scattering and deviations from the quark counting rules are illustrated.

W. van Driel, F. Combes, M. Arnaboldi, L. S. Sparke

A total of 33 polar ring galaxies and polar ring galaxy candidates were observed in the 21-cm HI line with the 64-m Parkes radio telescope. The objects, selected by their optical morphology, are all south of declination -39 degrees and in only 5 of them HI had been reported previously. HI line emission was detected towards 18 objects, though in 3 cases the d

Sebastien Majerowicz, Doris M. Neumann, Thomas H. Reiprich

We present a study of the medium distant cluster of galaxies Abell 1835 based on XMM-Newton data. The high quality of XMM-Newton data enable us to perform spectro-imaging of the cluster up to large radii. We determine the gas and total mass profiles based on the hydrostatic approach using the beta-model and the temperature profile. For the determination of t

Roser Valenti, T. Saha-Dasgupta, Claudius Gros

We investigate by means of ab initio electronic structure analysis and Quantum Monte Carlo calculations the scenario where longer-ranged magnetic interactions dominate over short-ranged interactions in the physical description of compounds. This question is discussed, in particular, for the case of CaCuGe$_2$O$_6$ which shows a spin-singlet behavior induced

Varun Sahni, Yuri Shtanov

We explore a new class of braneworld models in which the scalar curvature of the (induced) brane metric contributes to the brane action. The scalar curvature term arises generically on account of one-loop effects induced by matter fields residing on the brane. Spatially flat braneworld models can enter into a regime of accelerated expansion at late times. Th

Alexey Toporensky, Shinji Tsujikawa

We study nature of singularities in anisotropic string-inspired cosmological models in the presence of a Gauss-Bonnet term. We analyze two string gravity models-- dilaton-driven and modulus-driven cases-- in the Bianchi type-I background without an axion field. In both scenarios singularities can be classified in two ways- the determinant singularity where t

Phil Arras, Eanna E. Flanagan, Sharon M. Morsink, A. Katrin Schenk

Rossby waves (r-modes) in rapidly rotating neutron stars are unstable because of the emission of gravitational radiation. We study saturation of this instability by nonlinear transfer of energy to stellar "inertial" oscillation modes. We present detailed calculations of stellar inertial modes in the WKB limit, their linear damping by bulk and shear v

Akira Shimizu, Takayuki Miyadera, Akihisa Ukena

We study the stabilities of quantum states of macroscopic systems, against noises, against perturbations from environments, and against local measurements. We show that the stabilities are closely related to the cluster property, which describes the strength of spatial correlations of fluctuations of local observables, and to fluctuations of additive operato

K. S. Babu, S. M. Barr, Bumseok Kyae

In family unification models, all three families of quarks and leptons are grouped together into an irreducible representation of a simple gauge group, thus unifying the Standard Model gauge symmetries and a gauged family symmetry. Large orthogonal groups, and the exceptional groups $E_7$ and $E_8$ have been much studied for family unification. The main theo

Xiaoguang Wang, Paolo Zanardi

We show that in one-dimensional isotropic Heisenberg model two-qubit thermal entanglement and maximal violation of Bell inequalities are directly related with a thermodynamical state function, i.e., the internal energy. Therefore they are completely determined by the partition function, the central object of thermodynamics. For ferromagnetic ring we prove th

Marie Ericsson

This is a brief overview of quantum holonomies in the context of quantum computation. We choose an adequate set of quantum logic gates, namely, a phase gate, the Hadamard gate, and a conditional-phase gate and show how they can be implemented by purely geometric means. Such gates may be more resilient to certain types of errors.

C. Dullemond

A study is made of the behavior of unstable states in simple models which nevertheless are realistic representations of situations occurring in nature. It is demonstrated that a non-exponential decay pattern will ultimately dominate decay due to a lower limit to the energy. The survival rate approaches zero faster than the inverse square of the time when the

N. J. Cerf, S. Massar, S. Schneider

In order to study multipartite quantum cryptography, we introduce quantities which vanish on product probability distributions, and which can only decrease if the parties carry out local operations or carry out public classical communication. These ``secrecy monotones'' therefore measure how much secret correlations are shared by the parties. In the

Gebhard Gruebl

The quantum measurement problem as formalised by Bassi and Ghirardi [Phys. Lett. A 275 (2000)373] without taking recourse to sharp apparatus observables is extended to cover impure initial states.

Ramon Risco-Delgado

The inequality of Clauser and Horne [ Phys. Rev. D 10, 526 (1974)], intended to overcome the limited scope of other inequalities to deterministic theories, is shown to have a resticted validity even in case of perfect detectors and perfect angular correlations.

Alberto Casado, Trevor Marshall, Ramon Risco-Delgado, Emilio Santos

In previous articles we have developed a theory of down conversion in nonlinear crystals, based on the Wigner representation of the radiation field. Taking advantage of the fact that the Wigner function is always positive in parametric down conversion experiments, we construct a local hidden variables model where the amplitudes of the field modes are taken a

Petr Král, H. R. Sadeghpour

We show that circularly polarized light can spin nanotubes with GHz frequencies. In this method, angular moments of infrared photons are resonantly transferred to nanotube phonons and passed to the tube body by "umklapp" scattering. We investigate experimental realization of this ultrafast rotation in carbon nanotubes, levitating in an optical trap a

A. K. Aringazin

In this paper we overview some results on the hydrogen atom in external static uniform magnetic fields. We focus on the case of very strong magnetic field, B>>B_0=2.3x10^9 Gauss, use various approximate models and, particularly, in the adiabatic approximation have calculated exactly the integral defining the effective potential. This potential appears to be

A. I. Machavariani, Amand Faessler

The cross-sections of the $γp-γ' N'$, $γp-π' N'$ and $γp-γ'π' N'$ reactions are calculated in the framework of the field-theoretical one-particle ($π,ω,ρ$-mesons, nucleon and $Δ$-resonance) exchange model. Unlike the other relativistic approaches, our resulting amplitudes of the $γp$ multichannel reactions require one-variable cov

R. Rapp, E. V. Shuryak

The evolution of (non-strange) antibaryon abundances in the hadronic phase of central heavy-ion collisions is studied within a thermal equilibrium framework, based on the well-established picture of subsequent chemical and thermal freezeout. Due to large annihilation cross sections, antiprotons are, a priori, not expected to comply with this scheme. However,

V. Yu. Ponomarev

This article continues a discussion raised in previous publications (LANL preprint server, nucl-th/0202006 and nucl-th/0202020). I try to convince my opponents that general arguments are not "my case" and may be applied to their model.

Y. M. Zhao, A. Arima

We point out that the time reversal invariance, which was further interpreted by Velazquez et al. using the behaviors of $E_{cI}$ and $σ_I^2$, can not be the origin of the 0 g.s. dominance, as was pointed out previously by Bijker et al, and that the discussion by Velazquez et al. using a displaced TBRE is not true in general.

R. Klages, N. Korabel

Low-dimensional periodic arrays of scatterers with a moving point particle are ideal models for studying deterministic diffusion. For such systems the diffusion coefficient is typically an irregular function under variation of a control parameter. Here we propose a systematic scheme of how to approximate deterministic diffusion coefficients of this kind in t

Marc Toussaint

We present a generalization of conventional artificial neural networks that allows for a functional equivalence to multi-expert systems. The new model provides an architectural freedom going beyond existing multi-expert models and an integrative formalism to compare and combine various techniques of learning. (We consider gradient, EM, reinforcement, and uns

Marc Toussaint

A neural network with fixed topology can be regarded as a parametrization of functions, which decides on the correlations between functional variations when parameters are adapted. We propose an analysis, based on a differential geometry point of view, that allows to calculate these correlations. In practise, this describes how one response is unlearned whil

R. Andrushkiw, V. Gafiychuk, R. Zabrodsky

The computer simulation of quasistationary Stefan problem has been realized. Different representations of the Laplacian growth model are considered. The main attention has been paid for the interface dynamics represented by integro differential equations. Numerical approach has been realized by use of interpolating polynomials and exact quadrature formulae.

A. D. Alhaidari

As an extension of earlier work [J. Phys. A: Math. Gen. 34 (2001) 11273] we obtain analytic expressions for the scattering phase shift of M-term relativistic separable potential with Laguerre-type form factors and for M = 1, 2, and 3. We take the Dirac Hamiltonian as the reference Hamiltonian. Just like in the cited article, the tools of the relativistic J-m

A. Ghose Choudhury, A. Roy Chowdhury

A discrete nonlinear system is analysed in case of open chain boundary conditions at the ends. It is shown that the integrability of the system remains intact, by obtaining a modified set of Lax equations which automatically take care of the boundary conditions. The same Lax pair also conforms to the conditions stipulated by Sklyanin [5]. The quantum inverse

Pierre Cartier, Cecile DeWitt-Morette, Matthias Ihl, Christian Saemann

Parity is ubiquitous, but not always identified as a simplifying tool for computations. Using parity, having in mind the example of the bosonic/fermionic Fock space, and the framework of Z_2-graded (super) algebra, we clarify relationships between the different definitions of supermanifolds proposed by various people. In addition, we work with four complexes

Elizabeth Cockerill

In this paper we define a new class of metric spaces, called multi-model Cantor sets. We compute the Hausdorff dimension and show that the Hausdorff measure of a multi-model Cantor set is finite and non-zero. We then show that a bilipschitz map from one multi-model Cantor set to another has constant Radon-Nikodym derivative on some clopen. We use this to obt

John Lott

We give a lower bound on the number of small positive eigenvalues of the p-form Laplacian in a certain type of collapse with curvature bounded below.

Dimitry Leites

(A) The conventional integration theory on supermanifolds had been constructed in order to have (an analog of) the Stokes formula in which a~sub-supermanifold is of codimension $1=(1|0)$. I review other integrations and formulate related open problems: (1) On the $1|1$-dimensional superstring associated with the trivial bundle, in presence of a~contact struc

Grigori G. Amosov

Stationary quantum stochastic process j is introduced as a *-homomorphism embedding an involutive graded algebra $\tilde K=\oplus_{i=1}^{\infty}K_i$ into a ring of (abelian) cohomologies of the one-parameter group $α$ consisting of *-automorphisms of certain operator algebra in a Hilbert space such that every x from $K_i$ is translated into an additive $i-α$

Andrea Surroca

We study the set of algebraic numbers of bounded height and bounded degree where an analytic transcendental function takes algebraic values.

Yurii A. Neretin

We give a natural proof of the Ado theorem.

R. W. Bruggeman, R. J. Miatello, M. I. Pacharoni

We give density results for automorphic representations of Hilbert modular groups. In particular, we show that there are infinitely many automorphic representations that have a prescribed discrete series factor at some (but not all) real places.

Margarida Mendes Lopes, Rita Pardini

We give an up-to-date overview of the known results on the bicanonical map of surfaces of general type with $p_g=0$ and $K^2\ge 2$.

Sergei Gukov, David Tong

Using D2-brane probes, we study various properties of M-theory on singular, non-compact manifolds of G_2 and Spin(7) holonomy. We derive mirror pairs of N=1 supersymmetric three-dimensional gauge theories, and apply this technique to realize exceptional holonomy manifolds as both Coulomb and Higgs branches of the D2-brane world-volume theory. We derive a ``G

Sergei Gukov, David Tong

We describe how mirror symmetry of three-dimensional N=1 supersymmetric gauge theories can be used to determine the theory on the world-volume of a D2-brane probe of manifolds with G_2 holonomy. This is a much shortened companion paper to hep-th/0202126.

E. Buffenoir, K. Noui, P. Roche

We analyze the hamiltonian quantization of Chern-Simons theory associated to the universal covering of the Lorentz group SO(3,1). The algebra of observables is generated by finite dimensional spin networks drawn on a punctured topological surface. Our main result is a construction of a unitary representation of this algebra. For this purpose, we use the form

N. Mohammedi

A cosmological model based on Kaluza-Klein theory is studied. A metric, in which the scale factor of the compact space evolves as an inverse power of the radius of the observable universe, is constructed. The Freedmann-Robertson-Walker equations of standard four-dimensional cosmology are obtained precisely. The pressure in our universe is an effective pressu

A. J. M. Medved

Recently, Klemm and others [hep-th/0104141] have successfully generalized the Cardy-Verlinde formula for an asymptotically flat spacetime of arbitrary dimensionality. And yet, from a holographic perspective, the interpretation of this formula remains somewhat unclear. Nevertheless, in this paper, we incorporate the implied flat space/CFT duality into a study

Hans-Christian Pauli

The $\uparrow\downarrow$-model has produced the physical masses of all flavor-asymmetric mesons like the $π^\pm$ or the $ρ^\pm$. Can the same model also account for the flavor-symmetric mesons like the $π^0$ or the $ρ^0$? -- By adjusting one parameter in a $5\times5$-matrix, the $π$-$η$ degeneracy is lifted and the $η-η'$ splitting falls into the right b

G. M. Prosperi

I revue the so called Wilson loop approach to bound state problem in QCD. I shall show how using appropriate path integral representations for the quark propagator in an external field it is possible to obtain corresponding path integral representations for various types of gauge invariant Green functions which have the important feature of involving the gau

Vladimir Lugovoi

It is shown that even if a quark q is on the mass shell, the quark q' created via vacuum pair production in the process q -> h + q' has wide distribution for its spacelike virtuality, and so at the end of daughter string (q'\bar{q}) there is a parton having wide distributed spacelike virtuality. However, the essence of the parton model is to rega

A. F. Krutov, V. E. Troitsky

We extract the neutron charge form factor from the charge form factor of deuteron obtained from $T_{20}(Q^2)$ data at $0\le Q^2\le$ 1.717 (GeV$^2$). The extraction is based on the relativistic impulse approximation in the instant form of the relativistic Hamiltonian dynamics. Our results (12 new points) are compatible with existing values of the neutron char

G. Battistoni, A. Ferrari, P. R. Sala

Calculation of secondary particles produced by the interaction of cosmic rays with the nuclei of Earth's atmosphere pose important requirements to particle production models. Here we summarize the important features of hadronic simulations, stressing the importance of the so called ``microscopic'' approach, making explicit reference to the case o

R. A. Schneider, T. Renk, W. Weise

We propose a novel quasiparticle interpretation of the equation of state of deconfined QCD at finite temperature. Using appropriate thermal masses, we introduce a phenomenological parametrization of the onset of confinement in the vicinity of the phase transition. Lattice results of the energy density, the pressure and the interaction measure of pure SU(3) g

Hans-Christian Pauli

The session on effective Hamiltonians and chiral dynamics is overviewed, combined with a review on the bound-state problem. The progress during this session allows to remove all dependence on regularization in an effective interaction, thus to renormalize a Hamiltonian for the first time, and to solve front form as if they were instant-form equations, with a

Kimmo Kainulainen, Tomislav Prokopec, Michael G. Schmidt, Steffen Weinstock

We derive a semiclassical transport equation for fermions propagating in the presence of a CP-violating planar bubble wall at a first order electroweak phase transition. Starting from the Kadanoff-Baym (KB) equation for the two-point (Wightman) function we perform an expansion in gradients, or equivalently in the Planck constant h-bar. We show that to first

John Campbell, R. K. Ellis

We report on QCD radiative corrections to the processes p pbar --> W + 2 jets and p pbar --> Z + 2 jets at the Tevatron. These processes are included in the Monte Carlo program MCFM, which allows the calculation of any infra-red finite variable at next-to-leading order. Due to a better theoretical description of jets at next-to-leading order, some distributi

Arjun Berera

Warm inflation dynamics is reviewed. Results on dissipative scalar field dynamics relevant to warm inflation are examined and estimates of radiation production are given.

F. Palumbo

We propose a formulation of the QCD partition function which leads to a series expansion of the quark determinant in any given baryonic sector. The r-th term gives the gauge-invariant contribution of the valence quarks plus r quark-antiquark pairs. This expansion can be used to investigate any baryonic sector, starting from the nucleon up to high baryonic de

The OPAL collaboration, G. Abbiendi

The hadronic structure of the photon F2gamma is measured as a function of Bjorken x and of the photon virtuality Q2 using deep-inelastic scattering data taken by the OPAL detector at LEP at e+e- centre-of-mass energies from 183 to 209 GeV. Previous OPAL measurements of the x dependence of F2gamma are extended to an average Q2 of <Q2>=780GeV2 using data in th

ZEUS Collaboration

The photon-proton total cross section has been measured in the process e+ p -> e+ gamma p -> e+ X with the ZEUS detector at HERA. Events were collected with photon virtuality Q^2 < 0.02 GeV^2 and average gamma-p center-of-mass energy W_{gamma p} = 209 GeV in a dedicated run, designed to control systematic effects, with an integrated luminosity of 49 nb^{-1}.

Marcello Ortaggio

A new class of exact solutions is presented which describes impulsive waves propagating in the Nariai universe. It is constructed using a six-dimensional embedding formalism adapted to the background. Due to the topology of the latter, the wave front consists of two non-expanding spheres. Special sub-classes representing pure gravitational waves (generated b

H. T. Johnson-Steigelman, A. V. Brinck, P. F. Lyman

The formation of hafnium silicate films (HfSixOy) for use as gate oxides with large dielectric constant by solid state reaction of Hf metal and SiO2 was investigated. Thin, fully reacted silicate films could be formed, and were thermally stable in vacuum to temperatures in excess of 800 C. The interface between a hafnium silicate layer and the silicon substr

H. Scher, G. Margolin, R. Metzler, J. Klafter

We present a physical model to explain the behavior of long-term, time series measurements of chloride, a natural passive tracer, in rainfall and runoff in catchments [Kirchner et al., Nature 403(524), 2000]. A spectral analysis of the data shows the chloride concentrations in rainfall to have a white noise spectrum, while in streamflow, the spectrum exhibit

Kelly R. Patton, Michael R. Geller

The discrete nature of the vibrational modes of an isolated nanometer-scale solid dramatically modifies its low-energy electron and phonon dynamics from that of a bulk crystal. However, nanocrystals are usually coupled--even if only weakly--to an environment consisting of other nanocrystals, a support matrix, or a solid substrate, and this environmental inte

Ramiro Pino, Victor M. Villalba

We study the energy spectrum of the two-electron spherical parabolic quantum dot using the exact Schroedinger, the Hartree-Fock, and the Kohn-Sham equations. The results obtained by applying the shifted-1/N method are compared with those obtained by using an accurate numerical technique, showing that the relative error is reasonably small, although the first

L. C. Malacarne, R. S. Mendes, I. T. Pedron, E. K. Lenzi

An $N$-dimensional nonlinear Fokker-Planck equation is investigated here by considering the time dependence of the coefficients, where drift-controlled and source terms are present. We exhibit the exact solution based on the generalized gaussian function related to the Tsallis statistics. Furthermore, we show that a rich class of diffusive processes, includi

D. Sornette, V. F. Pisarenko

We analyze in details the statistical significance of the claim by Bird [2002] of a power law distribution of plate areas covering the Earth and confirm that the power law with exponent 0.25 +- 0.05 is the most robust and parsimonious model for all plates, including the very largest plates, when taking into account the constraint that the plates areas must s

Raluca A. Trasca, M. Mercedes Calbi, Milton W. Cole

We explore the thermodynamic behavior of gases adsorbed within a nanopore. The theoretical description employs a simple lattice gas model, with two species of site, expected to describe various regimes of adsorption and condensation behavior. The model includes four hypothetical phases: a cylindrical shell phase (S), in which the sites close to the cylindric

Valeria Del Prete, Alessandro Treves

In a previous report we have evaluated analytically the mutual information between the firing rates of N independent units and a set of continuous+discrete stimuli, for finite N and in the limit of large noise. Here, we extend the analysis to the case of two interconnected populations, where input units are linked to output ones via gaussian weights and a th

D. A. Garanin, R. Schilling

We consider the inverse Landau-Zener problem which consists in finding the energy-sweep functions W(t)=E1(t)-E2(t) resulting in the required time dependences of the level populations for a two-level system crossing the resonance one or more times during the sweep. We find sweep functions of particular forms that let manipulate the system in a required way, i

V. M. Zharkov

The new method of investigation of strongly correlated electronic system is presented. Using this method we have derived thee superstring from 2D Hubbard model. The novel expression for generalized supercoherent state has been calculated.

M. Guilleumas, D. M. Jezek, R. Mayol, M. Pi

We present a numerical method for generating vortex rings in Bose-Einstein condensates confined in axially symmetric traps. The vortex ring is generated using the line-source approximation for the vorticity, i.e., the rotational of the superfluid velocity field is different from zero only on a circumference of given radius located on a plane perpendicular to

Hagen Kleinert

Within a path integral formalism for non-Gaussian price fluctuations we set up a simple stochastic calculus and derive a natural martingale for option pricing from the wealth balance of options, stocks, and bonds. The resulting formula is evaluated for truncated Lévy distributions.

D. J. Reilly, T. M. Buehler, J. L. O&#39;Brien, A. R. Hamilton

There is controversy as to whether a one-dimensional (1D) electron gas can spin polarise in the absence of a magnetic field. Together with a simple model, we present conductance measurements on ultra low-disorder quantum wires supportive of a spin polarisation at B=0. A spin energy gap is indicated by the presence of a feature in the range 0.5 - 0.7 X 2e^2/h

Manabu Usuda, Noriaki Hamada, Takao Kotani, Mark van Schilfgaarde

We present a new, all-electron implementation of the GW approximation and apply it to wurtzite ZnO. Eigenfunctions computed in the local-density approximation (LDA) by the full-potential linearized augmented-plane-wave (LAPW) or the linearized muffin-tin-orbital (LMTO) method supply the input for generating the Green function G and the screened Coulomb inter

A. V. Nikulov

Theory alternative to the vortex lattice melting theories is advertised. The vortex lattice melting theories are science fiction cond-mat/9811051 because the Abrikosov state is not the vortex lattice with crystalline long-range order. Since the fluctuation correction to the Abrikosov solution is infinite in the thermodynamic limit (K.Maki and H.Takayama, 197

V. D. Krevchik, A. B. Grunin, A. K. Aringazin, M. B. Semenov

Within the framework of zero-range potential model in the ap-proach of effective mass, the impurity absorption by the complex Quantum Dot-Impurity Center in an external constant uniform magnetic field is considered. Under condition that the influence of a magnetic field on the ground state of quantum dot is negligible, we have derived the light absorption co

L. -M. Martinez, C. A. Angell

Recent efforts to deal with the complexities of the liquid state, particularly those of glassforming systems, have focused on the &#34;energy landscape&#34; as a means of dealing with the collective variables problem [1]. The &#34;basins of attraction&#34; that constitute the landscape features in configuration space represent a distinct class of microstates

C. A. Angell, S. Borick

In pursuit of understanding of the paradoxical success of the Adam-Gibbs equation in both experiment and computer simulation studies, we examine the relation between liquid behavior at constant pressure and constant volume and compare the inherent structures excitation profiles for the two cases. This allows us to extend qualitatively the recent correlation

S. V. Ghaisas

A continuum growth equation in 1+1 dimensions is obtained by considering the contributions to the underlying current from kinetics of adatoms on the surface. These considerations reproduce the slope dependent term that represents a stable or an unstable growth depending on the sign of the associated coefficient. In addition an h to -h symmetry breaking nonli

Li-Xin Li

A magnetic field connecting a Kerr black hole to a disk rotating around it can extract energy and angular momentum from the black hole and transfer them to the disk if the black hole rotates faster than the disk. The energy can be dissipated and radiated away by the disk, which makes the disk shine without the need of accretion. In this paper we present a to