April 2000 arXiv papers — page 13

Alexander V. Karzanov

Let $μ$ be a metric on a set T, and let c be a nonnegative function on the unordered pairs of elements of a superset $V\supseteq T$. We consider the problem of minimizing the inner product $c\cdot m$ over all semimetrics m on V such that m coincides with $μ$ within T and each element of V is at zero distance from T (a variant of the {\em multifacility locati

Satoru Iwata, Lisa Fleischer, Satoru Fujishige

This paper presents the first combinatorial polynomial-time algorithm for minimizing submodular set functions, answering an open question posed in 1981 by Grotschel, Lovasz, and Schrijver. The algorithm employs a scaling scheme that uses a flow in the complete directed graph on the underlying set with each arc capacity equal to the scaled parameter. The resu

Uwe Franz, Remi Leandre, Rene Schott

A derivation operator and a divergence operator are defined on the algebra of bounded operators on the symmetric Fock space over the complexification of a real Hilbert space $\eufrak{h}$ and it is shown that they satisfy similar properties as the derivation and divergence operator on the Wiener space over $\eufrak{h}$. The derivation operator is then used to

F. Bombal, I. Villanueva

We characterize those compact Hausdorff spaces K such that the proyective tensor product of C(K) by itself has the Dunford-Pettis Property, answering thus in the negative a question posed by Castillo and Gonzalez.

Vladimir V. Kornyak

Computer algebra methods are applied to investigation of spectral asymptotics of elliptic differential operators on curved manifolds with torsion and in the presence of a gauge field. In this paper we present complete expressions for the second coefficient (E_2) in the heat kernel expansion for nonminimal operator on manifolds with nonzero torsion. The expre

Victor Nistor

We show that a Lie algebroid on a stratified manifold is integrable if, and only if, its restriction to each strata is integrable. These results allow us to construct a large class of algebras of pseudodifferential operators.

Daniel R. Farkas

We present a formal, algebraic treatment of Fedosov's argument that the coordinate algebra of a symplectic manifold has a deformation quantization. His remarkable formulas are established in the context of affine symplectic algebras.

N. Grandi, R. L. Pakman, F. A. Schaposnik

We present a supersymmetric version of Dirac-Born-Infeld (DBI) theory in noncommutative space-time, both for Abelian and non-Abelian gauge groups. We show, using the superfield formalism, that the definition of a certain ordering with respect to the * product leads naturally to a DBI action both in the U(1) as well as in the U(N) case. BPS equations are anal

Brian R. Greene, Koenraad Schalm, Gary Shiu

We study M and F theory compactifications on Calabi-Yau four-folds in the presence of non-trivial background flux. The geometry is warped and belongs to the class of p-brane metrics. We solve for the explicit warp factor in the orbifold limit of these compactifications, compare our results to some of the more familiar recently studied warped scenarios, and d

B. U. Eden, P. S. Howe, E. Sokatchev, P. C. West

It is shown that certain extremal and next-to-extremal n-point correlators in four-dimensional N=2 superconformal field theories are free. These results hold for any gauge group.

L. R. Huiszoon, A. N. Schellekens

Open descendants with boundaries and crosscaps of non-trivial automorphism type are studied. We focus on the case where the bulk symmetry is broken to a Z_2 orbifold subalgebra. By requiring positivity and integrality for the open sector, we derive a unique crosscap of automorphism type g \in Z_2 and a corresponding g-twisted Klein bottle for a charge conjug

Marko Kolanovic, Silvio Pallua, Predrag Prester

We consider here the massive Thirring model regularized with the XYZ spin chain. We numerically calculate the mass ratios of particles which lie in the discrete part of the spectrum and obtain results in accordance with the DHN formula and in disagreement with recent calculations in the literature based on the numerical Bethe ansatz and infinite momentum fra

Chiang-Mei Chen, T. Harko, M. K. Mak

We study the low energy string effective action with an exponential type dilaton potential and vanishing torsion in a Bianchi type I space-time geometry. In the Einstein and string frames the general solution of the gravitational field equations can be expressed in an exact parametric form. Depending on the values of some parameters the obtained cosmological

Andre Lukas, Andrea Romanino

Motivated by the anomaly in the KARMEN experiment, we study new possibilities for brane-world models of neutrino masses. We show that the KARMEN anomaly can be understood in the context of a six-dimensional brane-world model. The fine-tuning problem associated with the single-particle interpretation of the anomaly is thereby alleviated. Our model shows some

Keith R. Dienes

In this talk, I discuss recent developments concerning the possibility of large extra spacetime dimensions. After briefly reviewing how such dimensions can lower the fundamental GUT, Planck, and string scales, I then outline how these scenarios lead to a new higher-dimensional seesaw mechanism for generating neutrino oscillations --- perhaps even without neu

Ashok Das

We discuss a few selected topics in finite temperature field theory.

A. Delgado, M. Quiros

In the four-dimensional supersymmetric standard model extended with gauge singlets the lightest Higgs boson mass, $M_H$, has an important contribution proportional to the squared of the superpotential coupling $λ$ of singlets to Higgs fields, $λSH_1\cdot H_2$. The requirement of perturbativity up to the unification scale yields an upper bound on $M_H\sim 140

Zhi-zhong Xing

We show that a CP-violating phase can be model-independently determined from the time-independent measurement of coherent B^0_s\bar{B}^0_s decays into (D^{(*)\pm}_s K^{(*)\mp})(D^{(*)\pm}_s K^{(*)\mp}) states at the Υ(5S) resonance. This phase amounts to (-γ) within the standard model, where γis the well-known angle of the quark mixing unitarity triangle. It

C. Bula, K. T. McDonald

The appears to exist no detailed calculation of the multiphoton trident process e + n omega_0 -> e' + e+e-, which can occur during the interaction of an electron beam with an intense laser beam. We present a calculation in the Weizsacker-Williams approximation that is in good agreement with QED calculations for the weak-field case.

H. V. Klapdor-Kleingrothaus, H. Päs, U. Sarkar

We discuss the potential of neutrinoless double beta decay for testing Lorentz invariance and the weak equivalence principle as well as contributions from dilaton exchange gravity in the neutrino sector. While neutrino oscillation bounds constrain the region of large mixing of the weak and gravitational eigenstates, we obtain new constraints on violations of

H. V. Klapdor-Kleingrothaus, H. Päs, U. Sarkar

The constraints from the non-observation of neutrinoless double beta decay on the violations of Lorentz invariance (VLI) or violations of the equivalence principle (VEP) have recently been re-examined (hep-ph/9904298) and it was claimed that the constraints are not valid. In this reply we point out that this statement is not correct and prove that the argume

O. Yavas, A. K. Ciftci, S. Sultansoy

Main parameters of different colliders which can be realized if a special 1 TeV energy linear electron accelerator or corresponding linear collider is constructed tangential to LHC are estimated. It is shown that L_ep=10^32cm^-2s^-1 at sqrt(s_ep)=5.29 TeV can be achieved within moderate upgrade of LHC parameters. Then, gamma-p collider with the same luminosi

Louis Crane

We propose a new line of attack to create a finite quantum theory which includes general relativity and (perhaps) the standard model in its low energy limit. The theory would emerge from the categorical approach. A structure is observed on the category of unitary representations of the lorentz group which we call hypergravity. This, combined with a study of

Sean A. Hayward

A definition of gravitational energy is proposed for any theory described by a diffeomorphism-invariant Lagrangian. The mathematical structure is a Noether- current construction of Wald involving the boundary term in the action, but here it is argued that the physical interpretation of current conservation is conservation of energy. This leads to a quasi-loc

Riccardo Benedetti, Enore Guadagnini

We introduce the (2+1)-spacetimes with compact space of genus g and with r gravitating particles which arise by ``Minkowskian suspensions of flat or hyperbolic cone surfaces'', by ``distinguished deformations'' of hyperbolic suspensions and by ``patchworking'' of suspensions. Similarly to the matter-free case, these spacetimes have ni

S. Q. Wu, X. Cai

Four classical laws of black hole thermodynamics are extended from exterior (event) horizon to interior (Cauchy) horizon. Especially, the first law of classical thermodynamics for Kerr-Newman black hole (KNBH) is generalized to those in quantum form. Then five quantum conservation laws on the KNBH evaporation effect are derived in virtue of thermodynamical e

Ronald F. Boisvert

This paper provides some reflections on the field of mathematical software on the occasion of John Rice's 65th birthday. I describe some of the common themes of research in this field and recall some significant events in its evolution. Finally, I raise a number of issues that are of concern to future developments.

Niels Asger Mortensen, Antti-Pekka Jauho, Karsten Flensberg

We study dephasing in semiconductor-superconductor structures caused by coupling to a voltage probe. We consider structures where the semiconductor consists of two scattering regions between which partial dephasing is possible. As a particular example we consider a situation with a double-barrier junction in the normal region. For a single-mode system we stu

K. R. Nikolaev, A. Yu. Dobin, I. N. Krivorotov, W. K. Cooley

Oscillations in the exchange coupling between ferromagnetic $La_{2/3}Ba_{1/3}MnO_3$ layers with paramagnetic $LaNiO_3$ spacer layer thickness has been observed in epitaxial heterostructures of the two oxides. This behavior is explained within the RKKY model employing an {\it ab initio} calculated band structure of $LaNiO_3$, taking into account strong electr

S. M. Gatica, G. Stan, M. M. Calbi, J. K. Johnson

We explore the equations of state and other properties of various quantum fluids (3He, 4He, their mixtures, and H_2) confined within individual carbon nanotubes. Above a threshold number of particles, N_a, the fluid density near the axis begins to grow above a negligibly small value. The properties of this axial fluid phase are sensitive to the tube size and

G. Benfatto, V. Mastropietro

An expansion based on renormalization group methods for the spin correlation function in the z direction of the Heisenberg-Ising XYZ chain with an external magnetic field directed as the z axis is derived. Moreover, by using the hidden symmetries of the model, we show that the running coupling constants are small, if the coupling in the z direction is small

Bo Lei, S. A. Aruna, Qiang-Hua Wang

Within the framework of the Ginzburg-Landau theory for $d_{x^2-y^2}+id_{xy}$-wave superconductors, we discuss the pairing state phase transition in the absence of the Zeeman coupling between the Cooper pair orbital angular momentum and the magnetic field. We find that above a temperature $T_{\ast}$, the pairing state in a magnetic field is pure $d_{x^{2}-y^{

G. Benfatto, V. Mastropietro

Using renormalization group methods, we study the Heisenberg-Ising XYZ chain in an external magnetic field directed as the z axis, in the case of small coupling J_3 in the z direction. We study the asymptotic behaviour of the spin space-time correlation function in the direction of the magnetic field and the singularities of its Fourier transform. The work i

Richard P. Sear

Slow dynamics in a fluid are studied in one of the most basic systems possible: polydisperse hard spheres. Monodisperse hard spheres cannot be studied as the slow down in dynamics as the density is increased is preempted by crystallisation. As the dynamics slow they become more heterogeneous, the spread in the distances traveled by different particles in the

S. K. Adhikari, M. Casas, A. Puente, A. Rigo

Bose-Einstein condensation (BEC) in two dimensions (2D) (e.g., to describe the quasi-2D cuprates) is suggested as the possible mechanism widely believed to underlie superconductivity in general. A crucial role is played by nonzero center-of-mass momentum Cooper pairs (CPs) usually neglected in BCS theory. Also vital is the unique {\it linear} dispersion rela

B. I. Ivlev

The interaction of bodies in a fluid, mediated by hydrodynamic fluctuations and proposed by Dzyaloshinskii, Lifshitz, and Pitaevskii, is calculated exactly for parallel infinite planes and is shown to be attractive. The second mechanism of fluctuation interaction, proposed in the present work, is due to fluctuations of linear and angular velocities of bodies

Dirk K. Morr, David Pines

Recent inelastic neutron scattering (INS) experiments on La$_{2-x}$Sr$_x$CuO$_4$ observed a {\it magnetic coherence effect}, i.e., strong frequency and momentum dependent changes of the spin susceptibility, $χ''$, in the superconducting phase. We show that this effect is a direct consequence of changes in the damping of incommensurate antiferromagnet

Razvan Florian, Serge Galam

Coalition setting among a set of actors (countries, firms, individuals) is studied using concepts from the theory of spin glasses. Given the distribution of respective bilateral propensities to either cooperation or conflict, the phenomenon of local aggregation is modeled. In particular the number of coalitions is determined according to a minimum conflict p

S. Jespersen, I. M. Sokolov, A. Blumen

Recently, Watts and Strogatz introduced the so-called small-world networks in order to describe systems which combine simultaneously properties of regular and of random lattices. In this work we study diffusion processes defined on such structures by considering explicitly the probability for a random walker to be present at the origin. The results are inter

P. Binder, D. Abraimov, A. V. Ustinov

We generate and observe discrete rotobreathers in Josephson junction ladders with open boundaries. Rotobreathers are localized excitations that persist under the action of a spatially uniform force. We find a rich variety of stable dynamic states including pure symmetric, pure asymmetric, and mixed states. The parameter range where the discrete breathers are

K. Ullakko, A. Sozinov, P. Yakovenko

A polycrystalline and single-crystal samples of near-stoichiometric Ni2MnGa alloys have been investigated. It was confirmed that martensite short crystallographic axis (c-axis) is the easy axis of magnetization. The reversible reorientation of the easy magnetization direction of martensite samples after 5% compression is found. The same reversible reorientat

E. P. Nakhmedov, H. Feldmann, R. Oppermann, M. Kumru

Low temperature quantum corrections to the density of states (DOS) and the conductivity are examined for a two-dimensional(2D) square crystal with substitutional impurities. By summing the leading logarithmic corrections to the DOS its energy dependence near half-filling is obtained. It is shown that substitutional impurities do not suppress the van Hove sin

Andreas Wensauer, Oliver Steffens, Michael Suhrke, Ulrich Roessler

We present ground-state calculations for laterally coupled quantum dots containing 2, 4, and 8 electrons. As our emphasis is on spin effects our results are obtained by applying spin-density functional theory (SDFT). By varying the distance between the centers of the coupled quantum dots, the transition from weak to strong coupling situation is realized. For

F. Brosens, J. T. Devreese, L. F. Lemmens

Based on the Hellman-Feynman theorem it is shown that the average square radius of a cloud of interacting bosons in a parabolic well can be derived from their free energy. As an application, the temperature dependence of the moment of inertia of non-interacting bosons in a parabolic trap is determined as a function of the number of bosons. Well below the cri

Abhishek Dhar, B. Sriram Shastry, Chandan Dasgupta

We study the equilibrium and dynamical properties of the ANNNI (axial next-nearest-neighbor Ising) chain at the multiphase point. An interesting property of the system is the macroscopic degeneracy of the ground state leading to finite zero-temperature entropy. In our equilibrium study we consider the effect of softening the spins. We show that the degenerac

Ulf Griesmann, Rainer Kling

We have made the first interferomeric measurements of the wavelengths of the important ultraviolet diagnostic lines in the spectra \ion{C}{4} near 155 nm and \ion{Si}{4} near 139 nm with a vacuum ultraviolet Fourier transform spectrometer and high-current discharge sources. The wavelength uncertainties were reduced by one order of magnitude for the \ion{C}{4

Nickolay Y. Gnedin

I show how the existing observational data on Local Group dwarf galaxies can be used to estimate the average star formation law during the first 3 Gyr of the history of the universe. I find that the observational data are consistent with the orthodox Schmidt law with a star formation efficiency of about 4 percent if the star formation is continuous (during t

Frits Paerels, Erik Kuulkers, John Heise, Duane A. Liedahl

Recently, the detection of discrete features in the X-ray afterglow spectra of GRB970508 and GRB970828 was reported. The most natural interpretation of these features is that they are redshifted Fe K emission complexes. The identification of the line emission mechanism has drastic implications for the inferred mass of radiating material, end hence the nature

N. W. Evans, M. I. Wilkinson

This paper argues that the Milky Way galaxy is probably the largest member of the Local Group. The evidence comes from estimates of the total mass of the Andromeda galaxy (M31) derived from the three dimensional positions and radial velocities of its satellite galaxies, as well as the projected positions and radial velocities of its distant globular clusters

D. A. Baiko, P. Haensel

We analyze cooling of neutron stars, assuming the presence of localized protons in the densest region of their cores. Choosing a single threshold density for proton localization and adjusting neutron star mass, we reproduce the observational data on effective surface temperatures of Vela and PSR 0656+14, with or without an accreted hydrogen envelope. However

G. Weigelt, D. Mourard, L. Abe, U. Beckmann

We have built an infrared beam combiner for the GI2T/REGAIN interferometer of the Observatoire de la Cote d'Azur. The beam combiner allows us to record spectrally dispersed Michelson interference fringes in the near-infrared J-, H- or K-bands. The beam combiner has the advantage that Michelson interferograms can simultaneously be recorded in about 128 di

P. Haensel, K. P. Levenfish, D. G. Yakovlev

The bulk viscosity of the neutron star matter due to the direct Urca processes involving nucleons, electrons and muons is studied taking into account possible superfluidity of nucleons in the neutron star cores. The cases of singlet-state pairing or triplet-state pairing (without and with nodes of the superfluid gap at the Fermi surface) of nucleons are cons

G. Thuma, N. Neininger, U. Klein, R. Wielebinski

The starburst galaxy M82 has been mapped at 1.2 mm using the IRAM 30-m telescope and the MPIfR 19-channel bolometer. The influence of the sidelobe pattern and the 12CO(2-1) line has been carefully analyzed. Based on this analysis, we conclude that the cold dust does not extend far into the halo as has been previously claimed. The total mass of dust in the in

Jozef Klacka

Solutions of the two-body problem with the simultaneous action of the solar electromagnetic radiation in the form of the Poynting-Robertson effect are discussed. Special attention is devoted to pseudo-circular orbits and terminal values of osculating elements. The obtained results complete those of Klacka and Kaufmannova (1992) and Breiter and Jackson (1998)

Sergio Campana, Luigi Stella, Sandro Mereghetti, Davide Cremonesi

We report on a 61 ks BeppoSAX observation of the soft X-ray transient Cen X-4 during quiescence which allowed to study the source X-ray spectrum from ~ 0.3 keV to ~ 8 keV. A two-component spectral model was required, consisting of a black body with temperature of ~ 0.1 keV and a power law with photon index ~ 2. These values are compatible with earlier ASCA r

Benjamin D. Wandelt, Krzysztof M. Gorski, Eric Hivon

We apply the Pseudo-C_l formalism to obtain an unbiased, approximate method for efficient simultaneous estimation of several cosmological parameters from large, almost full-sky cosmic microwave background data sets.

Shanil N. Virani, Reinhold Mueller-Mellin, Paul P. Plucinsky, Yousaf M. Butt

The Chandra X-ray Observatory (CXO) was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of approximately 63.5 hours (~ 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be perfo

Itzhak Bars

The conformal symmetry SO(d,2) of the massless particle in d dimensions, or superconformal symmetry OSp(N|4), SU(2,2|N), OSp(8|N) of the superparticle in d=3,4,6 dimensions respectively, had been previously understood as the global Lorentz symmetry and supersymmetries of 2T physics in d+2 dimensions. By utilising the gauge symmetries of 2T physics, it is sho

Rosa Murphy Williams, Robert Petre, You-Hua Chu, C. -H. Rosie Chen

We examine the supernova remnant (SNR) 0540-697 in the Large Magellanic Cloud (LMC) using data from the Chandra ACIS. The X-ray emission from this SNR had previously been hidden in the bright emission of nearby X-ray binary LMC X-1; however, new observations with Chandra can finally reveal the SNR's structure and spectrum. We find the SNR to be a thick-s

Lin Yan, P. J. McCarthy, R. J. Weymann, M. A. Malkan

We present a catalog of extremely red objects discovered using the NICMOS/HST parallel imaging database and ground-based optical follow-up observations. Within an area of 16 square arc-minutes, we detect 15 objects with $\rm R - F160W > 5$ and $\rm F160W < 21.5$. We have also obtained K-band photometry for a subset of the 15 EROs. All of the $\rm R - F160W$

S. Bhattacharyya, A. V. Thampan, R. Misra, B. Datta

We calculate the temperature profiles of (thin) accretion disks around rapidly rotating neutron stars (with low surface magnetic fields), taking into account the full effects of general relativity. We then consider a model for the spectrum of the X-ray emission from the disk, parameterized by the mass accretion rate, the color temperature and the rotation ra

V. M. Pudalov, G. Brunthaler, A. Prinz, G. Bauer

We report studies of the magnetoresistance (MR) in a two-dimensional electron system in (100) Si-inversion layers, for perpendicular and parallel orientations of the current with respect to the magnetic field in the 2D-plane. The magnetoresistance is almost isotropic; this result does not support the suggestion of the orbital origin of the MR in Si-inversion

A. Feinstein, K. E. Kunze, M. A. Vazquez-Mozo

We study inflation and entropy generation in a recently proposed pre-big-bang model universe produced in a collision of gravitational and dilaton waves. It is shown that enough inflation occurs provided the incoming waves are sufficiently weak. We also find that entropy in this model is dynamically generated as the result of the nonlinear interaction of the

Hisakazu Minakata, Hiroshi Nunokawa

We uncover an interesting phenomenon that neutrino flavor transformation in slowly varying matter density imitates almost exactly that of vacuum neutrino oscillation under suitably chosen experimental parameters. It allows us to have relatively large CP violating measure ΔP \equiv P(ν_μ \to ν_e) - P(\barν_μ \to \barν_e) which is essentially free from matter

Adam Falkowski, Zygmunt Lalak, Stefan Pokorski

We supersymmetrize a class of moduli dependent potentials living on branes with the help of additional bulk terms in 5d N=2 supergravity. The space of Poincare invariant vacuum solutions includes the Randall-Sundrum solution and the $M$-theoretical solution. After adding gauge sectors to the branes we discuss breakdown of low energy supersymmetry in this set

Sergey A. Vitkalov, Hairong Zheng, K. M. Mertes, M. P. Sarachik

Measurements in magnetic fields applied at small angles relative to the electron plane in silicon MOSFETs indicate a factor of two increase of the frequency of Shubnikov-de Haas oscillations at H>H_{sat}. This signals the onset of full spin polarization above H_{sat}, the parallel field above which the resistivity saturates to a constant value. For H<H_{sat}

Marek Nowakowski

We derive the `exact&#39; Newtonian limit of general relativity with a positive cosmological constant $Λ$. We point out that in contrast to the case with $Λ= 0 $, the presence of a positive $Λ$ in Einsteins&#39;s equations enforces, via the condition $| Φ| \ll 1$, on the potential $Φ$, a range ${\cal R}_{max}(Λ) \gg r \gg {\cal R}_{min} (Λ)$, within which th

Lev I. Deych, Alexey Yamilov, Alexander A. Lisyansky

The concept of local polaritons is used to describe optical properties of mixed crystals in the frequency region of their {\it restrahlen} band. It is shown that this concept allows for a physically transparent explanation of the presence of weak features in the spectra of so called one-mode crystals, and for one-two mode behavior. The previous models were a

A. Vedyayev, D. Bagrets, A. Bagrets, B. Dieny

The tunnel magnetoresistance (TMR) of F/O/F magnetic junctions, (F&#39;s are ferromagnetic layers and O is an oxide spacer) in the presence of magnetic impurities within the barrier, is investigated. We assume that magnetic couplings exist both between the spin of impurity and the bulk magnetization of the neighboring magnetic electrode, and between the spin

M. Hirsch, M. A. Diaz, W. Porod, J. C. Romao

The simplest unified extension of the MSSM with bi-linear R--Parity violation naturally predicts a hierarchical neutrino mass spectrum, in which one neutrino acquires mass by mixing with neutralinos, while the other two get mass radiatively. We have performed a full one-loop calculation of the neutralino-neutrino mass matrix in the bi-linear \rp MSSM, taking

Meghan E. Gray, Richard S. Ellis, Alexandre Refregier, Jocelyn Bezecourt

We present the first detection of a gravitational depletion signal at near-infrared wavelengths, based on deep panoramic images of the cluster Abell 2219 (z=0.22) taken with the Cambridge Infrared Survey Instrument (CIRSI) at the prime focus of the 4.2m William Herschel Telescope. Infrared studies of gravitational depletion offer a number of advantages over

A. Deppeler, A. J. Millis

We use the dynamical mean field theory to develop a systematic and computationally tractable method for studying electron-phonon interactions in systems with arbitrary electronic correlations. The method is formulated as an adiabatic expansion around the limit of static phonons. No specific electronic groundstate is assumed. We derive an effective low-freque

Tetsufumi Hirano

We analyze the second Fourier coefficient $v_2$ of the pion azimuthal distribution in non-central heavy-ion collisions in a relativistic hydrodynamic model. The exact treatment of the decay kinematics of resonances leads to almost vanishing azimuthal anisotropy of pions near the midrapidity, while the matter elliptic flow is in-plane at freeze-out. In additi

Georg Foltin

We consider a D-dimensional fluid membrane in a D+1-dimensional embedding space, subject to quantum fluctuations. The corresponding action is invariant under coordinate transformations and depends only on the shape of the membrane and its variation, neglecting tangential degrees of freedom. We calculate the resulting field theory to one loop order in a D=eps

Alexander P. Bakulev, Rusko Ruskov, Klaus Goeke, N. G. Stefanis

Applying arguments based on the operator product expansion for a three-point correlator and relying on quark-hadron duality, we derive an expression for the skewed (non-forward) parton distribution in the pion in the case of a zero-skewedness parameter, {\cal F}^{ψ|π}_{ζ=0}(X;t). We expect that our result is relevant for moderately large momentum transfers 1

Y. -Y. Keum, Otto C. W. Kong

We present the full result for the down squark mass-squared matrix in the complete theory of supersymmetry without R-parity where all kind of R-parity violating terms are admitted without bias. An optimal parametrization, the single-VEV parametrization, is used. The major result is a new contribution to $LR$ squark mixing, involving both bilinear and triline

Meng Chen

Let X be a projective 3-fold with at most Q-factorial terminal singularities on which K_X is nef and big. Suppose the canonical index r(X)>1. For any positive integer m, it is interesting to consider the base point freeness and birationality of the divisor mK_X. For example, we know the following results: (1) the system |5rK_X| is base point free (Ein-Lazars

Gautam Bhattacharyya, Subhendu Rakshit, Amitava Raychaudhuri

If the neutrino mass is non-zero, as hinted by several experiments, then R-parity-violating supersymmetric Yukawa couplings can drive a heavy neutrino decay into lighter states. The heavy neutrino may either decay radiatively into a lighter neutrino, or it may decay into three light neutrinos through a Z-mediated penguin. For a given mass of the decaying neu

H. Frusawa, R. Hayakawa

We discuss the validity of generalized Debye-Hückel (GDH) equation proposed by Fisher {\itshape et al.} from the functional integral point of view. The GDH theory considers fluctuations around prescribed densities of positive and negative charges. Hence we first formulate a density functional integral expression for the canonical system of Coulomb gas, and a

Otto C. W. Kong

Within the framework of the complete theory of supersymmetry without R-parity, where all possible R-parity violating terms are admitted, we perform a systematic analytical study of all sources of neutrino masses up to ``direct one-loop&#34; (defined explicitly below) level. In the passing, we present the full result for squark and slepton masses. In particul

G. A. Alekseev, J. B. Griffiths

For space-times with two spacelike isometries, we present infinite hierarchies of exact solutions of the Einstein and Einstein--Maxwell equations as represented by their Ernst potentials. This hierarchy contains three arbitrary rational functions of an auxiliary complex parameter. They are constructed using the so called `monodromy transform&#39; approach an

Alain Riazuelo, Jean-Philippe Uzan

We investigate some aspects of quintessence models with a non-minimally coupled scalar field and in particular we show that it can behave as a component of matter with $-3 \lesssim P/ρ\lesssim 0$. We study the properties of gravitational waves in this class of models and discuss their energy spectrum and the cosmic microwave background anisotropies they indu

A. Gorsky, A. Vainshtein, A. Yung

We consider chiral condensates in SU(2) gauge theory with broken N=2 supersymmetry. The matter sector contains an adjoint multiplet and one fundamental flavor. Matter and gaugino condensates are determined by integrating out the adjoint field. The only nonperturbative input is the Affleck-Dine-Seiberg (ADS) superpotential generated by one instanton plus the

Paulo A. Maia Neto, Diego A. R. Dalvit

We consider the interaction of an harmonic oscillator with the quantum field via radiation pressure. We show that a `Schrodinger cat&#39; state decoheres in a time scale that depends on the degree of `classicality&#39; of the state components, and which may be much shorter than the relaxation time scale associated to the dynamical Casimir effect. We also sho

Ilki Kim, Guenter Mahler

Generalized uncertainty relations may depend not only on the commutator relation of two observables considered, but also on mutual correlations, in particular, on entanglement. The equivalence between the uncertainty relation and Bohr&#39;s complementarity thus holds in a much broader sense than anticipated.

Mark S. Byrd, Paul B. Slater

Due to considerable recent interest in the use of density matrices for a wide variety of purposes, including quantum computation, we present a general method for their parameterizations in terms of Euler angles. We assert that this is of more fundamental importance than (as several people have remarked to us) ``just another parameterization of the density ma

A. M. Steane, D. M. Lucas

We first consider the basic requirements for a quantum computer, arguing for the attractiveness of nuclear spins as information-bearing entities, and light for the coupling which allows quantum gates. We then survey the strengths of and immediate prospects for quantum information processing in ion traps. We discuss decoherence and gate rates in ion traps, co

M. C. de Oliveira, N. G. Almeida, S. S. Mizrahi, M. H. Y. Moussa

We have revisited the Ghirardi-Rimini-Weber-Pearle (GRWP) approach for continuous dynamical evolution of the state vector for a macroscopic object. Our main concern is to recover the decoupling of the state vector dynamics for the center-of-mass (CM) and internal motion, as in the GRWP model, but within the framework of the standard cosmology. In this connec

P. Roy, R. Roychoudhury

We use a Lie algebraic technique to construct complex quasi exactly solvable potentials with real spectrum. In particular we obtain exact solutions of a complex sextic oscillator potential and also a complex potential belonging to the Morse family.

Bing Hurl, Zhi-Yong Wang Hai-Dong Zhang

Through the analysis of the definition of the duration of proper time of a particle given by the length of its world line, we show that there is no transitivity of the coordinate time function derived from the definition, so there exists an ambiguity in the determination of the duration of the proper time for the particle. Its physical consequence is illustr

Hrachya B. Nersisyan, Amal K. Das

In this paper we report on our theoretical studies of various aspects of the correlated stopping power of two point-like ions (a dicluster) moving in close but variable vicinity of each other in some metallic target materials the latter being modelled by a degenerate electron gas with appropriate densities. Within the linear response theory we have made a co

R. Bijker, A. Frank, S. Pittel

Low-lying states in nuclei are investigated using an ensemble of random interactions. Both in the nuclear shell model and in the interacting boson model we find a dominance of $J^P=0^+$ ground states. It is shown that this feature is not due to time reversal symmetry. In the shell model, evidence is found for the occurrence of pairing properties, and in the

I. Vidaña, A. Polls, A. Ramos, L. Engvik

We present results from Brueckner-Hartree-Fock calculatons for beta stable neutron star matter with nucleonic and hyperonic degress degrees of freedom, employing the most recent parametrizations of the baryon-baryon interaction of the Nijmegen group. It is found that the only strange baryons emergin in beta stable matter up to total barionic densities of 1.2

E. Oset, M. J. Vicente Vacas

The meson meson interaction in the scalar sector in the presence of a nuclear medium is studied with particular attention to the change of the properties of the f0(980) and a0(980) resonances. By using a chiral unitary approach which generates the f0 and a0 resonances and reproduces their free properties, we find that the position of the resonances in the me

L. Martina, S. Lafortune, P. Winternitz

The Lie symmetries of a large class of generalized Toda field theories are studied and used to perform symmetry reduction. Reductions lead to generalized Toda lattices on one hand, to periodic systems on the other. Boundary conditions are introduced to reduce theories on an infinite lattice to those on semi-infinite, or finite ones.

S. Lafortune, P. Winternitz, L. Martina

A class of two-dimensional field theories with exponential interactions is introduced. The interaction depends on two ``coupling&#39;&#39; matrices and is sufficiently general to include all Toda field theories existing in the literature. Lie point symmetries of these theories are found for an infinite, semi-infinite and finite number of fields. Special atte

Yuri S. Kivshar, Andrey A. Sukhorukov, Elena A. Ostrovskaya, Tristram J. Alexander

We discuss several novel types of multi-component (temporal and spatial) envelope solitary waves that appear in fiber and waveguide nonlinear optics. In particular, we describe multi-channel solitary waves in bit-parallel-wavelength fiber transmission systems for high performance computer networks, multi-colour parametric spatial solitary waves due to cascad

G. Roepstorff, Ch. Vehns

The Clifford action on superspaces is analyzed with a view on generalized Dirac fields taking values in some Clifford supermodule. the stress is here on two principles: complexification and polarisation. For applications in field theory, the underlying vector space may carry either a Euclidean or a Minkowskian structure.

S. P. Novikov

Family of doublings of Hopf algeras based on the product of algebra and its dual are constructed and studied. Special cases of these construction may be considered as natural quantum analogs of rings of differential operators on groups. Such constructions appeared in 1966-67 in the authors works in the complex cobordism theory. These constructions do not lee

S. P. Novikov

Symplectic vector-valued scalar product is constructed on the spaces of solutions of the real discrete Shrodinger equation with fixed value of the spectral parameter on graphs. It takes values in the first homology group of the graph. This scalar product plays fundamental role in the Scattering theory for the graphs with tails. In particular, all unitarity p