February 2003 arXiv papers — page 10

M. S. Shikakhwa, N. K. Pak

A partial wave analysis using the basis of the total angular momentum operator J_3 is carried out for the first order Born amplitude of a Dirac particle in an Aharonov-Bohm (AB)potential. It is demonstrated that the s-partial wave contributes to the scattering amplitude in contrast to the case with scalar non-relativistic particles.We suggest that this expla

D. Dudal, H. Verschelde, V. E. R. Lemes, M. S. Sarandy

The effective potential for an on-shell BRST invariant gluon-ghost condensate of mass dimension 2 in the Curci-Ferrari gauge in SU(N) Yang-Mills is analysed by combining the local composite operator technique with the algebraic renormalization. We pay attention to the gauge parameter independence of the vacuum energy obtained in the considered framework and

J. Kalkkinen, K. S. Stelle

We show how to cast an interacting system of M--branes into manifestly gauge-invariant form using an arrangement of higher-dimensional Dirac surfaces. Classical M--theory has a cohomologically nontrivial and noncommutative set of gauge symmetries when written using a ``doubled'' formalism containing 3-form and 6-form gauge fields. We show how the arr

A. A. Broyles

A technique for avoiding infinite integrals in the calculation of the one-loop diagram contribution to the vacuum polarization component of an atomic energy level is presented. This makes renormalization unnecessary. Infinite integrals do not occur because, as it is shown, no delta functions are required for the Green's functions. Thus there are none to

E. L. da Graça, H. L. Carrion, R. de Lima Rodrigues

Using the Wigner-Heisenberg algebra for bosonic systems in connection with oscillators we find a new representation for the Virasoro algebra.

Glennys R. Farrar, Gabrijela Zaharijas

Strongly attractive color forces in the flavor singlet channel may lead to a stable H dibaryon. Here we show that an H or other compact, flavor singlet hadron is unlikely to bind to nuclei, so that bounds on exotic isotopes do not exclude their stability. Remarkably, a stable H appears to evade other experimental constraints as well, when account is taken of

T. M. Aliev, M. Savci

We calculate the penguin form factor for the (B -> eta l^+ l^-) decay. This form factor is calculated in light cone QCD sum rules, including contributions from wave functions up to twist-4, as well as mass corrections of the light (eta) meson.

Alexander Gemintern, Shaouly Bar-Shalom, Gad Eilam, Frank Krauss

Lepton-flavor-violating decays of the type L->l gamma gamma (mu->e gamma gamma, tau->e gamma gamma, and tau->mu gamma gamma) are proposed as new probes of R-parity-violating supersymmetry. Non-penguin diagrams with a sneutrino that decays into two photons via a triangle graph might trigger such decays even in the absence of the corresponding radiative decays

K. J. Eskola, H. Honkanen, V. J. Kolhinen, Jianwei Qiu

The effects of the first nonlinear corrections to the DGLAP equations are studied in light of the HERA data. Saturation limits are determined in the DGLAP+GLRMQ approach for the free proton and for the Pb nucleus.

Carlos A. Salgado, Urs Achim Wiedemann

We calculate the probability (``quenching weight'') that a hard parton radiates an additional energy fraction due to scattering in spatially extended QCD matter. This study is based on an exact treatment of finite in-medium path length, it includes the case of a dynamically expanding medium, and it extends to the angular dependence of the medium-indu

A. Misaki, T. S. Sinegovskaya, S. I. Sinegovsky, N. Takahashi

The prompt muon contribution to the deep-sea atmospheric muon flux can serve as a tool for probing into the small-x feature of the gluon density inside of a nucleon, if the muon energy threshold could be lifted to 100 TeV. The prompt muon flux underwater is calculated taking into consideration predictions of recent charm production models in which the small-

Anjan S. Joshipura, Subhendra Mohanty

Electroweak radiative corrections can generate the neutrino (mass)$^2$ difference required for the large mixing angle solution (LMA) to the solar neutrino problem if two of the neutrinos are assumed degenerate at high energy. We test this possibility with the existing experimental knowledge of the low energy neutrino mass and mixing parameters. We derive res

Stefan Weinzierl

Perturbative calculations at next-to-next-to-leading order for multi-particle final states require a method to cancel infrared singularities. I discuss the subtraction method at NNLO. As a concrete example I consider the leading-colour contributions to e+ e- --> 2 jets. This is the simplest example which exhibits all essential features. For this example, exp

Arif I. Shoshi

We develop a model to compute high-energy reactions of hadrons and photons. The perturbative interaction is described by gluon exchange and the non-perturbative interaction by the stochastic vacuum model which leads to quark-confinement in dipoles via a string of color fields. We study the QCD structure of the dipole-dipole scattering in momentum space focus

A. A. Arkhipov

In this note we present additional arguments in favour of Kaluza and Klein picture of the world. We show that geniusly simple formula provided by Kaluza-Klein approach gives an excellent description for the mass spectrum of two-nucleon system. It has also been established that the experimental data obtained at low energies where the nucleon-nucleon dynamics

Thomas Becher, Kirill Melnikov

We calculate the fermion self-energy at O(alpha_s) for the Symanzik improved staggered fermion action used in recent lattice simulations by the MILC collaboration. We demonstrate that the algebraic approach to lattice perturbation theory, suggested by us recently, is a powerful tool also for improved lattice actions.

Shoji Hashimoto, Masataka Okamoto

The anisotropic lattice fermion actions are investigated with the one-loop perturbative calculations aiming at constructing a formulation for heavy quark with controlled systematic uncertainties. For the heavy-light systems at rest the anisotropic lattice with small temporal lattice spacing $a_t$ suppresses the discretization error by a power of $a_t m_Q$ fo

The OPAL collaboration, G. Abbiendi

We observed Bose-Einstein correlation in pi0 pairs produced in Z0 decays using the data sample collected by the OPAL detector at LEP 1 from 1991 to 1995. Using a static Gaussian picture for the pion emitter source, we obtain the chaoticity parameter lambda = 0.55 +- 0.10 +- 0.10 and the source radius R = (0.59 +- 0.08 +- 0.05) fm. according to the JETSET and

Juri Agresti, Roberto De Pietri, Luca Lusanna, Luca Martucci

A Hamiltonian linearization of the rest-frame instant form of tetrad gravity (gr-qc/0302084), where the Hamiltonian is the weak ADM energy ${\hat E}_{ADM}$, in a completely fixed (non harmonic) 3-orthogonal Hamiltonian gauge is defined. For the first time this allows to find an explicit solution of all the Hamiltonian constraints and an associated linearized

Juri Agresti, Roberto De Pietri, Luca Lusanna, Luca Martucci

In the framework of the rest-frame instant form of tetrad gravity, where the Hamiltonian is the weak ADM energy ${\hat E}_{ADM}$, we define a special completely fixed 3-orthogonal Hamiltonian gauge, corresponding to a choice of {\it non-harmonic} 4-coordinates, in which the independent degrees of freedom of the gravitational field are described by two pairs

C. Bona, T. Ledvinka, C. Palenzuela, M. Zacek

A general covariant extension of Einstein\'{}s field equations is considered with a view to Numerical Relativity applications. The basic variables are taken to be the metric tensor and an additional four-vector $Z_μ$. Einstein's solutions are recovered when the additional four-vector vanishes, so that the energy and momentum constraints amount to the

Herbert Edelsbrunner, Alper Ungor

We introduce relaxed scheduling as a paradigm for mesh maintenance and demonstrate its applicability to triangulating a skin surface in $\Rspace^3$.

Alejandro Javier Garcia, Guillermo Ricardo Simari

The work reported here introduces Defeasible Logic Programming (DeLP), a formalism that combines results of Logic Programming and Defeasible Argumentation. DeLP provides the possibility of representing information in the form of weak rules in a declarative manner, and a defeasible argumentation inference mechanism for warranting the entailed conclusions. In

S. Schwieger, M. Potthoff, W. Nolting

Recent photoemission experiments have shown strong surface modifications in the spectra from vanadium oxides as (V,Cr)_2O_3 or (Sr,Ca)VO_3. The effective mass is enhanced at the surface and the coherent part of the surface spectrum is narrowed as compared to the bulk. The quasiparticle weight is more sensitive at the surface than in the bulk against bandwidt

F. Rivadulla, J. -S. Zhou, J. B. Goodenough

We report an unconventional temperature dependence of the resistivity in several strongly correlated systems approaching a localized to itinerant electronic transition from the itinerant electron side. The observed resistivity, proportioanl to T^(3/2)over the entire range of materials discussed, cannot be explained within the framework of existing theories.

N. Stojic, J. W. Davenport, M. Komelj, J. Glimm

Recently, there has been an increased interest in first-principles calculations of the actinides as well as in finding the new materials which display surface magnetism. We predict the existence of a magnetic moment on the uranium (001) surface by performing density functional calculations for a slab geometry in the generalized gradient and local spin densit

Jean Pierre Boon, Patrick Grosfils, James F. Lutsko

We consider the general problem of the first passage distribution of particles whose displacements are subject to time delays. We show that this problem gives rise to a \emph{propagation-dispersion equation} which is obtained as the continuous limit of the exact microscopic \emph{first visit equation}. The propagation-dispersion equation should be contrasted

Xavier Oriols

The effect of exchange interaction on the two-terminal conductance of fully ballistic samples is studied using a many-particle wave packet formalism. The approach shows that the puzzling nonuniversal conductance quantization can be explained as a fermion exchange interaction effect. The Landauer conductance step Go is obtained when two-fermion interaction is

Andrea Baldassarri, Umberto Marini Bettolo Marconi, Andrea Puglisi

We study the formation and the dynamics of correlations in the velocity field for 1D and 2D cooling granular gases with the assumption of negligible density fluctuations (``Homogeneous Velocity-correlated Cooling State'', HVCS). It is shown that the predictions of mean field models fail when velocity fluctuations become important. The study of correl

C. R. Simovski, B. Sauviac

The properties of artificial isotropic microwave composites which would possess simultaneously negative permittivity and permeability are studied theoretically. Four kinds of composites are considered. Two of them concern media with split-ring resonator particles with different particle arrangements. The other two are realized with Omega particles. An analyt

S. Bruehne, R. Sterzel, E. Uhrig, C. Gross

A new approach to solve quasicrystalline atomic structures in 3-dimensional (3D) real space is presented: The atomic pair distribution function (PDF) of face centred icosahedral Ho9Mg26Zn65 [a(6D) = 2x5.18(3)A was obtained from in-house X-ray diffraction data (MoKa1). Starting with rational approximant models, derived from 1/1- and 2/1-Al-Mg-Zn, its local an

R. Gilardi, S. Streule, A. J. Drew, U. Divakar

The magnetic phase diagram of slightly overdoped La{2-x}Sr{x}CuO{4} (x=0.17) is characterised by a field-induced hexagonal to square transition of the vortex lattice at low fields (~0.4 Tesla) [R. Gilardi et al., Phys. Rev. Lett. 88, 217003 (2002)]. Here we report on a small angle neutron scattering study of the vortex lattice at higher fields, that reveals

R. Heid, B. Renker, H. Schober, P. Adelmann

The phonon density-of-states of transition metal diborides TMB2 with TM = Ti, V, Ta, Nb and Y has been measured using the technique of inelastic neutron scattering. The experimental data are compared with ab initio density functional calculations whereby an excellent agreement is registered. The calculations thus can be used to obtain electron-phonon spectra

E. Räsänen, H. Saarikoski, V. N. Stavrou, A. Harju

We study the ground state properties of rectangular quantum dots by using the spin-density-functional theory and quantum Monte Carlo methods. The dot geometry is determined by an infinite hard-wall potential to enable comparison to manufactured, rectangular-shaped quantum dots. We show that the electronic structure is very sensitive to the deformation, and a

Martin Howard, Andrew D. Rutenberg

We examine fluctuation effects due to the low copy number of proteins involved in pattern-forming dynamics within a bacterium. We focus on a stochastic model of the oscillating MinCDE protein system regulating accurate cell division in E. coli. We find that, for some parameter regions, the protein concentrations are low enough that fluctuations are essential

Pedro A. Pury, Manuel O. Caceres

An algebraic derivation is presented which yields the exact solution of the mean first-passage and mean residence times of a one-dimensional asymmetric random walk for quenched disorder. Two models of disorder are analytically treated. Both, absorbing-absorbing and reflecting-absorbing boundaries are considered. Particularly, the interplay between asymmetry

M. K. Karkkainen, S. A. Tretyakov, S. I. Maslovski, P. A. Belov

Numerical study of evanescent fields in an isotropic backward-wave (BW) (double negative or "left-handed") slab is performed with the FDTD method. This system is expected to be able to restore all spatial Fourier components of the spectrum of a planar source, including evanescent fields, realizing a "superlens". The excitation of surface mode

T. Domanski

We consider a possibility to describe the Feshbach resonance in terms of the Boson Fermion (BF) model. Using such model we show that after a gradual disentangling of the boson from fermion subsystem the resonant type scattering between fermions is indeed generated. We decouple the subsystems via: (a) the single step, and (b) the continuous canonical transfor

Pavol Farkasovsky

The $f$ and $d$ electron density of states of the one-dimensional Falicov-Kimball model are studied in the weak-coupling limit by exact diagonalization calculations. The resultant behaviors are used to examine the $d$-electron gap ($Δ_{d}$), the $f$-electron gap ($Δ_{f}$), and the $fd$-electron gap ($Δ_{fd}$) as functions of the $f$-level energy $E_f$ and hy

A. K. Prykarpatsky, V. V. Gafiychuk

From the sandpoint of neural network dynamics we consider dynamical system of special type pesesses gradient (symmetric) and Hamiltonian (antisymmetric) flows. The conditions when Hamiltonian flow properties are dominant in the system are considered. A simple Hamiltonian has been studied for establishing oscillatory patern conditions in system under consider

T. Schneider, R. Khasanov, K. Conder, H. Keller

We study the oxygen isotope (^{16}O,^{18}O) and finite size effects in Y_{1-x}Pr_{x}Ba_{2}Cu_{3}O_{7-δ} by in-plane penetration depth (λ_{ab}) measurements. A significant change of the length L_{c} of the superconducting domains along the c-axis and λ_{ab}^{2} is deduced, yielding the relative isotope shift ΔL_{c}/L_{c}\approx Δλ_{ab}^{2}/λ_{ab}^{2}\approx -

Francesco Guerra, Fabio Lucio Toninelli

In this paper, we study the high temperature or low connectivity phase of the Viana-Bray model. This is a diluted version of the well known Sherrington-Kirkpatrick mean field spin glass. In the whole replica symmetric region, we obtain a complete control of the system, proving annealing for the infinite volume free energy, and a central limit theorem for the

H. Hong, Beom Jun Kim, M. Y. Choi

We investigate the response behavior of an Ising system, driven by an oscillating field, on a small-world network, with particular attention to the effects of the system size. The responses of the magnetization to the driving field are probed by means of Monte Carlo dynamic simulations with the rewiring probability varied. It is found that at low and high te

Alok Shukla, Haranath Ghosh, S. Mazumdar

Within a rigid-band correlated electron model for oligomers of poly-(paraphenylene) (PPP) and poly-(paraphenylenevinylene) (PPV), we show that there exist two fundamentally different classes of two-photon A$_g$ states in these systems to which photoinduced absorption (PA) can occur. At relatively lower energies there occur A$_g$ states which are superpositio

Shan-Ho Tsai, D. P. Landau

Monte-Carlo simulations and ground-state calculations have been used to map out the phase diagram of a system of classical spins, on a simple cubic lattice, where nearest-neighbor pairs of spins are coupled via competing antiferromagnetic superexchange and ferromagnetic double-exchange interactions. For a certain range of parameters, this model is relevant f

Shan-Ho Tsai, Alex Bunker, D. P. Landau

Using a recently implemented integration method [Krech et. al.] based on an iterative second-order Suzuki-Trotter decomposition scheme, we have performed spin dynamics simulations to study the critical dynamics of the BCC Heisenberg antiferromagnet with uniaxial anisotropy. This technique allowed us to probe the narrow asymptotic critical region of the model

Min Shen, Semion Saikin, Ming-C. Cheng, Vladimir Privman

Monte Carlo simulations are performed to study the in-plane transport of spin-polarized electrons in III-V semiconductor quantum wells. The density matrix description of the spin polarization is incorporated in the simulation algorithm. The spin-orbit interaction terms generate coherent evolution of the electron spin polarization and also cause dephasing. Th

J. Strand, B. D. Schultz, A. F. Isakovic, C. J. Palmstrom

Electrical spin injection from Fe into Al$_x$Ga$_{1-x}$As quantum well heterostructures is demonstrated in small (< 500 Oe) in-plane magnetic fields. The measurement is sensitive only to the component of the spin that precesses about the internal magnetic field in the semiconductor. This field is much larger than the applied field and depends strongly on the

L. I. Glazman, M. Pustilnik

We review the mechanisms of low-temperature electron transport across a quantum dot weakly coupled to two conducting leads. Conduction in this case is controlled by the interaction between electrons. At temperatures moderately lower than the single-electron charging energy of the dot, the linear conductance is suppressed by the Coulomb blockade. Upon further

C. Tappert, A. Bianchini

We present calibrated photometry and time-resolved spectroscopy of the cataclysmic variable GZ Cnc. Radial velocities of the H-alpha emission line reveal an orbital period of 0.08825(28) d, or 2.118(07) h, placing the system at the lower edge of the period gap. One of our observations catches the system on the rise to an overlooked, possibly small-amplitude,

Andrew Gould, Alice C. Quillen

The star S0-2, which is orbiting Sgr A* with a 15-yr period, almost certainly did not form in situ. We propose that it was injected into this close orbit by the tidal disruption of a massive-star binary, whose primary was more massive than S0-2 and at least 60 Msun. From numerical integrations we find that 1-2% of incoming binaries with closest approach equa

V. Luridiana, E. Perez, M. Cervino

We revise the physical conditions in the O++ zone of the planetary nebula NGC 6543, obtaining two different estimates of the electron temperature (Te) and one estimate of the electron density (Ne). The electron temperature is computed by means of two independent methods, the nebular-to-auroral ratio [O III] 5007/4363, and the diagnostic diagram that combines

Michiel Reuland, Wil van Breugel, Huub Roettgering, Wim de Vries

Perhaps as many as 10% of high redshift radio galaxy (HzRG; z > 2) candidates that are selected using an Ultra Steep radio Spectrum (USS) criterion fail to show optical emission (continuum, lines) in deep Keck exposures. Their parent objects are only detected in the near-IR and are probably heavily obscured and/or at very high redshift. To search for signatu

Takamitsu Miyaji, Yoshitaka Ishisaki, Yoshihiro Ueda, Yasushi Ogasaka

We have observed a radio-quiet QSO Kaz 102 (z=0.136) with ASCA as a part of our program of complete spectral characterization of hard X-ray selected AGNs. We found that Kaz 102 shows unusual spectral properties. A simple power-law with absorption in our galaxy gave a satisfactory description of the spectrum. However, it showed a very hard photon index of Gam

Patrick M. Motl, Jack O. Burns, Chris Loken, Michael L. Norman

We present a new scenario for the formation of cool cores in rich galaxy clusters based on results from recent high spatial dynamic range, adaptive mesh Eulerian hydrodynamic simulations of large-scale structure formation. We find that cores of cool gas, material that would be identified as a classical cooling flow based on its X-ray luminosity excess and te

Torsten A. Ensslin, Corina Vogt

The autocorrelation function and similarly the Fourier-power spectrum of a rotation measure (RM) map of an extended background radio source can be used to measure components of the magnetic autocorrelation and power-spectrum tensor within a foreground Faraday screen. It is possible to reconstruct the full non-helical part of this tensor in the case of an iso

G. S. Bisnovatyi-Kogan

Many phenomena such as stellar variability, stellar explosions, behavior of different kind of X-ray and gamma-ray sources, processes in active galactic nuclei and other astrophysical objects show stochastic features. Brief description of these phenomena is given in this review.

C. Nipoti, P. Londrillo, L. Ciotti

We explore the effects of dissipationless merging on the Fundamental Plane of elliptical galaxies by using a N-body code based on a new, high performance numerical scheme (Dehnen 2002). We investigate the extreme cases of galaxy growth by equal mass merging and accretion of small stellar systems; in a subset of simulations we also consider the presence of da

S. Madsen

The internal velocity structure in the Hyades cluster as seen by Hipparcos is compared with realistic N-body simulations using the NBODY6 code, which includes binary interaction, stellar evolution and the Galactic tidal field. The model allows to estimate reliably the accuracy of astrometric radial velocities in the Hyades as derived by Lindegren et al. (200

E. Ferrero, W. Brinkmann

We present the results of XMM-Newton observations of four high-z quasars, two radio-loud and two radio-quiet. One of the radio-loud objects, PKS 2126-158, clearly shows absorption in excess of the galactic value as claimed before from ASCA and ROSAT observations. For PKS 2149-306 the evidence for excess absorption is only marginal in contrast to previous res

Sergei Nayakshin

The black hole in our Galactic Center is extremely underluminous for the amount of hot gas available for accretion. Theoretical understanding of this fact rests on a likely but not entirely certain assumption that the electrons in the accreting gas are much cooler than the protons. In this case the hot gas as a whole is too hot to accrete, and is too tenous

M. Dall&#39;Ora, V. Ripepi, F. Caputo, V. Castellani

We present new BV time series data of the Carina dwarf spheroidal galaxy. Current data cover an area of about 0.3 square degrees around the center of the galaxy and allowed us to identify 92 variables. Among them 75 are RR Lyrae stars, 15 are &#34;bona fide&#34; Anomalous Cepheids, one might be a Galactic field RR Lyrae, and one is located along the Carina R

Emmanouel Rovilos, Philip J. Diamond, Colin J. Lonsdale, Carol J. Lonsdale

We present MERLIN observations of the continuum (both 1.6 and 5 GHz) and OH maser emission towards Arp220. the correct spatial configuration of the various componnents of the galaxy is revealed. In the eastern component the masers are shown to be generally coincident with the larger scale continuum emission; in the west, the masers and continuum do not gener

K. Lehtinen, J. Harju, S. Kontinen, James L. Higdon

The low-mass star formation region associated with the reflection nebula Cederblad 110 in the Chamaeleon I cloud was mapped with the Australian Telescope Compact Array (ATCA) at 6 and 3.5cm. Altogether 11 sources were detected, three of which are previously known low mass young stellar objects associated with the nebula: the illuminating star IRS2 (Class III

Eric Emsellem

I present here an heterogeneous selection of nearby galaxies in which inner density waves (bars, spirals, m=1 modes) have been observed, and which are presumed to host a supermassive black hole, to illustrate the importance of such inner waves in the fueling of the central 10s of parsecs.

S. S. Gershtein, A. A. Logunov, M. A. Mestvirishvili

It is noticed that the total relative density of mass in the Universe Omega_tot should exceed 1, i.e. Omega_tot=1+f^2/6 according to the field relativistic theory of gravity (RTG), which is free of the cosmological singularity and which provides the Euclidean character for the 3-dimensional space. Here f is the ratio of the graviton mass m_g to the contempor

B. W. Jiang, A. Omont, S. Ganesh, G. Simon

A 0.35\degr $\times$ 0.29\degr field centered at $l$=--18.63\degr, $b$=0.35\degr was observed during the ISOGAL survey by ISOCAM imaging at 7$μ$m and 15{\rm $μ$m}. 648 objects were detected and their brightness are measured. By combining with the DENIS data in the near-infrared J and K$_{\rm S}$ bands, one derives the extinction at 7{\rm $μ$m} through ${\rm

Jian-Min Wang

(abbreviated) We show that there is a limit relation between the black hole mass and the width at the half maximum of H$β$ for active galactic nuclei (AGNs) with super-Eddington accretion rates. When a black hole has a super-Eddington accretion rate, the empirical relation of reverberation mapping has two possible ways. First, it reduces to a relation betwee

Martin Asplund

Stellar model atmospheres form the basis for any element abundance determination and hence are crucial ingredients for studies of stellar, galactic and cosmic evolution. With recent observational progress with the advent of 8m-class telescopes and efficient spectrographs, the dominant source of uncertainty today originates with the assumptions and approximat

Martin Asplund, Remo Collet

Recently 3D hydrodynamical simulations of stellar surface convection have become feasible thanks to advances in computer technology and efficient numerical algorithms. Available observational diagnostics indicate that these models are highly realistic in describing the topology of stellar granulation and for spectral line formation purposes. The traditional

Martin Asplund

I describe recent progress in terms of 3D hydrodynamical model atmospheres and 3D line formation and their applications to stellar abundance analyses of late-type stars. Such 3D studies remove the free parameters inherent in classical 1D investigations (mixing length parameters, macro- and microturbulence) yet are highly successful in reproducing a large ars

M. Asplund, M. Carlsson, A. Botnen

The lithium abundances in metal-poor halo stars are of importance for cosmology, galaxy evolution and stellar structure. In an attempt to study possible systematic errors in the derived Li abundances, the line formation of LiI lines has been investigated by means of realistic 3D hydrodynamical model atmospheres of halo stars and 3D non-LTE radiative transfer

Joseph D. MacMillan, Richard N. Henriksen

This poster discusses a possible explanation for the relationship between the mass of the central supermassive black hole and the velocity dispersion in the bulge of the host galaxy. We suppose that the black hole and the dark matter halo are forming simultaneously as matter falls in, and a self-similar system then exists in which the mass and the velocities

Christina Sormani

In the Friedmann Model of the universe, cosmologists assume that spacelike slices of the universe are Riemannian manifolds of constant sectional curvature. This assumption is justified via Schur&#39;s Theorem by stating that the spacelike universe is locally isotropic. Here we define a Riemannian manifold as almost locally isotropic in a sense which allows b

Alexandre d&#39;Aspremont, Laurent El Ghaoui

We consider the problem of computing upper and lower bounds on the price of a European basket call option, given prices on other similar baskets. Although this problem is very hard to solve exactly in the general case, we show that in some instances the upper and lower bounds can be computed via simple closed-form expressions, or linear programs. We also int

Cheuk-Yin Wong

We study the effects of a collective flow and multiple scattering on two-particle correlation measurements in Hanbury-Brown-Twiss intensity interferometry. We find that under a collective flow the effective source distribution in a two-particle correlation measurement depends on the initial source distribution. In addition, it depends on a collective flow ph

Jerome P. Gauntlett, Dario Martelli, Daniel Waldram

We systematically analyse the necessary and sufficient conditions for the preservation of supersymmetry for bosonic geometries of the form R^{1,9-d} \times M_d, in the common NS-NS sector of type II string theory and also type I/heterotic string theory. The results are phrased in terms of the intrinsic torsion of G-structures and provide a comprehensive clas

Mao-Pei Tsui, Mu-Tao Wang

Let f be a smooth map between unit spheres of possibly different dimensions. We prove the global existence and convergence of the mean curvature flow of the graph of f under various conditions. A corollary is that any area-decreasing map between unit spheres (of possibly different dimensions) is homotopic to a constant map.

Ilia Gogoladze, Yukihiro Mimura, S. Nandi

We consider the unification of gauge, Higgs as well as the matter fields in a 6D N=2 supersymmetric SU(8) gauge theory. The gauge symmetry SU(8) is broken down to SU(4) x SU(2)_L x SU(2)_R x U(1)^2 in 4D through T^2/Z_6 orbifold compactification, and the theory is reduced to 4D N=1 supersymmetric Pati-Salam model. The electroweak Higgs fields as well as the

Subir Sarkar

The standard Big Bang cosmology predicts the existence of an, as yet undetected, relic neutrino background, similar to the photons observed in the cosmic microwave background. If neutrinos have mass, then such relic neutrinos are a natural candidate for the dark matter of the universe, and indeed were the first particles to be proposed for this role. This po

I. Bars, I. Kishimoto, Y. Matsuo

We propose an analytic framework to study the nonperturbative solutions of Witten&#39;s open string field theory. The method is based on the Moyal star formulation where the kinetic term can be split into two parts. The first one describes the spectrum of two identical half strings which are independent from each other. The second one, which we call midpoint

A. Blaut, M. Daszkiewicz, J. Kowalski-Glikman

We propose a new Doubly Special Relativity theory based on the generalization of the $κ$-deformation of the Poincaré algebra acting along one of the null directions. We recall the quantum Hopf structure of such deformed Poincaré algebra and use it to derive the phase space commutation relations. As in the DSR based on the standard quantum $κ$-Poincaré algebr

Narutaka Ozawa, Sorin Popa

We prove several unique prime factorization results for tensor products of type II_1 factors coming from groups that can be realized either as subgroups of hyperbolic groups or as discrete subgroups of connected Lie groups of real rank 1. In particular, we show that if $R \otimes LF_{r_1} \otimes ... \otimes LF_{r_m}$ is isomorphic to a subfactor in $R \otim

Anton V. Galajinsky

Recently it was conjectured by Gibbons and Townsend that the large n limit of an N=4 superconformal extension of the n-particle Calogero model might provide a microscopic description of the extreme Reissner-Nordstrom black hole near the horizon. In this paper a possibility to construct an SU(1,1|2) invariant extension of the Calogero model is considered. We

C. Giunti

It is shown that the 99% confidence limits from the analyses of the data of cosmological and neutrino experiments imply a small marginally allowed region in the space of the neutrino oscillation parameters of 3+1 four-neutrino mixing schemes. This region can be confirmed or falsified by experiments in the near future.

A. Dedes, S. Heinemeyer, S. Su, G. Weiglein

We investigate the physics of the lightest CP-even MSSM Higgs boson at the Tevatron, the LHC, a linear e+e- collider, a gamma gamma collider and a mu+mu- collider. The analysis is performed in the three most prominent soft SUSY-breaking scenarios, mSUGRA, mGMSB and mAMSB. For all colliders the observability and parameter regions with suppressed production cr

E. Sharpe

In this paper we make two observations related to discrete torsion. First, we observe that an old obscure degree of freedom (momentum/translation shifts) in (symmetric) string orbifolds is related to discrete torsion. We point out how our previous derivation of discrete torsion from orbifold group actions on B fields includes these momentum lattice shift pha

M. Augsburger, P. Ackerbauer, W. H. Breunlich, M. Cargnelli

We report on an experiment at the Paul Scherrer Institute, Villigen, Switzerland measuring x rays from muon transfer from deuterium to helium. Both the ground state transfer via the exotic dmu3,4He* molecules and the excited state transfer from mud* were measured. The use of CCD detectors allowed x rays from 1.5 keV to 11 keV to be detected with sufficient e

ZEUS Collaboration

Dijet angular distributions of photoproduction events in which a $D^{*\pm}$ meson is produced in association with one of two energetic jets have been measured with the ZEUS detector at HERA, using an integrated luminosity of 120 pb$^{-1}$. Differential cross sections as a function of the angle between the charm-jet and the proton-beam direction in the dijet

Guenter Sigl, Francesco Miniati, Torsten Ensslin

We simulate propagation of cosmic ray nucleons above 10^{19} eV in scenarios where both the source distribution and magnetic fields within about 50 Mpc from us are obtained from an unconstrained large scale structure simulation. We find that consistency of predicted sky distributions with current data above 4 x 10^{19} eV requires magnetic fields of ~0.1 mic

H. Fakhri, A. Imaanpur

In this article we construct the chirality and Dirac operators on noncommutative AdS_2. We also derive the discrete spectrum of the Dirac operator which is important in the study of the spectral triple associated with AdS_2. It is shown that the degeneracy of the spectrum present in the commutative AdS_2 is lifted in the noncommutative case. The way we const

q Collaboration, F. Farchioni, C. Gebert, I. Montvay

The dependence of the pseudoscalar meson mass and decay constant is compared to one-loop Partially Quenched Chiral Perturbation Theory (PQChPT) in a numerical simulation with two light dynamical quarks. The characteristic behaviour with chiral logarithms is observed. The values of the fitted PQChPT-parameters are in a range close to the expectation in contin

Harald Dorn, Christoph Sieg

Projecting on a suitable subset of coordinates, a picture is constructed in which the conformal boundary of $AdS_5\times S^5$ and that of the plane wave resulting in the Penrose limit are located at the same line. In a second line of arguments all $AdS_5\times S^5$ and plane wave geodesics are constructed in their integrated form. Performing the Penrose limi

E. P. van den Ban, H. Schlichtkrull

Let X = G/H be a reductive symmetric space and K a maximal compact subgroup of G. The image under the Fourier transform of the space of K-finite compactly supported smooth functions on X is characterized.

D. Damanik, D. Lenz

We consider dynamical systems arising from substitutions over a finite alphabet. We prove that such a system is linearly repetitive if and only if it is minimal. Based on this characterization we extend various results from primitive substitutions to minimal substitutions. This includes applications to random Schrödinger operators and to number theory.

Changhyun Ahn, Yutaka Ookouchi

We extend the results of Cachazo, Seiberg and Witten to N=1 supersymmetric gauge theories with gauge groups SO(2N), SO(2N+1) and Sp(2N). By taking the superpotential which is an arbitrary polynomial of adjoint matter \Phi as a small perturbation of N=2 gauge theories, we examine the singular points preserving N=1 supersymmetry in the moduli space where mutua

Zhi Zhao, Tao Yang, Yu-Ao Chen, An-Ning Zhang

We report the first experimental violation of local realism in four-photon Greenberger-Horne-Zeilinger (GHZ) entanglement. In the experiment, the non-statistical GHZ conflicts between quantum mechanics and local realism are confirmed, within the experimental accuracy, by four specific measurements of polarization correlations between four photons. In additio

K. Hasebe

In bilayer quantum Hall (BLQH) systems at $ν$=2, three different kinds of ground states are expected to be realized, i.e. a spin polarized phase (spin phase), a pseudospin polarized phase (ppin phase) and a canted antiferromagnetic phase (C-phase). An SU(4) scheme gives a powerful tool to investigate BLQH systems which have not only the spin SU(2) but also t

Nikos Apostolakis

We prove the existence of a finite set of moves sufficient to relate any two representations of the same 3-manifold as a 4-fold simple branched covering of S^3. We also prove a stabilization result: after adding a fifth trivial sheet two local moves suffice. These results are analogous to results of Piergallini in degree 3 and can be viewed as a second step

S. Itzkovitz, R. Milo, N. Kashtan, G. Ziv

Understanding the subgraph distribution in random networks is important for modelling complex systems. In classic Erdos networks, which exhibit a Poissonian degree distribution, the number of appearances of a subgraph G with n nodes and g edges scales with network size as \mean{G} ~ N^{n-g}. However, many natural networks have a non-Poissonian degree distrib