June 2006 arXiv papers — page 12

Guido Pezzini

Let G be a semisimple connected linear algebraic group over C, and X a wonderful G-variety. We study the possibility of realizing X as a closed subvariety of the projective space of a simple G-module. We describe the wonderful varieties having this property as well as the linear systems giving rise to such immersions. We also prove that any ample line bundle

John Lott

We consider modified scalar curvature functions for Riemannian manifolds equipped with smooth measures. Given a Riemannian submersion whose fiber transport is measure-preserving up to constants, we show that the modified scalar curvature of the base is bounded below in terms of the scalar curvatures of the total space and fibers. We give an application conce

Gunther Cornelissen, Karim Zahidi

Julia Robinson has given a first-order definition of the rational integers Z in the rational numbers Q by a formula (\forall \exists \forall \exists)(F=0) where the \forall-quantifiers run over a total of 8 variables, and where F is a polynomial. This implies that the Σ_5-theory of Q is undecidable. We prove that a conjecture about elliptic curves provides a

John Lott, Cedric Villani

We define a notion of a measured length space X having nonnegative N-Ricci curvature, for N finite, or having infinity-Ricci curvature bounded below by K, for K a real number. The definitions are in terms of the displacement convexity of certain functions on the associated Wasserstein space P_2(X) of probability measures. We show that these properties are pr

Martin Bojowald, Aureliano Skirzewski

Effective equations are often useful to extract physical information from quantum theories without having to face all technical and conceptual difficulties. One can then describe aspects of the quantum system by equations of classical type, which correct the classical equations by modified coefficients and higher derivative terms. In gravity, for instance, o

Fabio Scardigli, Roberto Casadio

We reply to the comments by P.Midodashvili about our previous paper [1]. We argue that, contrary to the conclusions in Refs. [2,3], the Generalized Uncertainty Principle proposed by Ng and van Dam in Ref. [4] is compatible with the Holographic Principle in spacetimes with extra dimensions only for a very special (and somehow unrealistic) choice of the relati

Y. Brihaye, E. Radu

We present new solutions of the $d=5$ Einstein-Yang-Mills theory describing black holes with squashed horizons. These configurations are asymptotically locally flat and have a boundary topology of a fibre bundle $R\times S^1 \hookrightarrow S^{2}$. In a $d=4$ picture, they describe black hole solutions with both nonabelian and U(1) magnetic charges.

Allan Rosencwaig

We derive the electromagnetic self-energy and the radiative correction to the gyromagnetic ratio of a free electron using a Casimir energy approach. This method provides an attractive and straightforward physical basis for the renormalization process.

L. Alejandro Correa-Borbonet

In this letter it is proposed another generalization of the Verlinde's maps for the case $Λ\neq 0$. Thermodynamical arguments combined with this proposal conduce to a inverse square-law cosmological term behavior.

S. Mert Aybat, Lance J. Dixon, George Sterman

The resummation of soft gluon exchange for QCD hard scattering requires a matrix of anomalous dimensions. We compute this matrix directly for arbitrary 2 to n massless processes for the first time at two loops. Using color generator notation, we show that it is proportional to the one-loop matrix. This result reproduces all pole terms in dimensional regulari

Yu. S. Surovtsev, R. Kaminski, D. Krupa, M. Nagy

Analysis of the isoscalar S- and D-waves of processes pi-pi-> pi-pi, K-Kbar, eta-eta is carried out aimed at studying the status and QCD nature of scalar and tensor mesons below 2 GeV and 2.3 GeV, respectively. Assignment of these mesons to lower scalar and tensor nonets is proposed.

I. N. Mishustin, L. M. Satarov, W. Greiner

Within a thermal model we estimate possible multiplicities of scalar glueballs in central Au+Au collisions at AGS, SPS, RHIC and LHC energies. For the glueball mass in the region 1.5-1.7 GeV, the model predicts on average (per event) 0.5-1.5 glueballs at RHIC and 1.5-4 glueballs at LHC energies. Possible enhancement mechanisms are discussed.

Pierre Hosteins

We introduce a method to extract the right-handed neutrino mass matrix from the Left-Right symmetric seesaw formula and apply it to the study of a simple SUSY SO(10) theory. We find 8 possible solutions for the heavy neutrino spectrum and a richer phenomenology than in the pure type I or type II seesaw mechanism. Leptogenesis is studied in SO(10) and can be

Z. Q. Wang, X. F. Lu, Fan Wang

APE smearing and overlap-Dirac operator are combined to filter QCD vacuum configurations. The results obtained from overlap fermions and improved 5Li cooling are compared, both of them exhibit structures of dilute liquid of instanton. Finally the overlap fermions, improved 5Li cooling and APE smearing are combined to calculate the topological charge and iden

The BABAR Collaboration, B. Aubert

We report the first observation of $e^+e^-$ annihilations into states of positive $C$-parity, namely $ρ^0 ρ^0$ and $ϕρ^0$. The two states are observed in the $\pip\pim\pip\pim$ and $K^+K^-\pip\pim$ final states, respectively, in a data sample of 225~$fb^{-1}$ collected by the $BaBar$~experiment at the $PEP-II$ $e^+e^-$ storage rings at energies near $\sqrt{s

Thomas Kluge

An overview is given of analyses in DIS at HERA which confront the predictions of power corrections with measured data. These include mean values and distributions of 2-jet as well as 3-jet event shape variables and jet rates.

Piotr T. Chruściel

We study the question of local and global uniqueness of completions, based on null geodesics, of Lorentzian manifolds. We show local uniqueness of such boundary extensions. We give a necessary and sufficient condition for existence of unique maximal completions. The condition is verified in several situations of interest. This leads to existence and uniquene

Zheng-Cheng Gu, Xiao-Gang Wen

A local quantum bosonic model on a lattice is constructed whose low energy excitations are gravitons described by linearized Einstein action. Thus the bosonic model is a quantum theory of gravity, at least at the linear level. We find that the compactification and the discretization of metric tenor are crucial in obtaining a quantum theory of gravity.

B. T. Seaman, M. Kraemer, D. Z. Anderson, M. J. Holland

Atomtronics focuses on atom analogs of electronic materials, devices and circuits. A strongly interacting ultracold Bose gas in a lattice potential is analogous to electrons in solid-state crystalline media. As a consequence of the band structure, cold atoms in a lattice can exhibit insulator or conductor properties. P-type and N-type material analogs can be

Kartick Tarafder, Atisdipankar Chakrabarti, Kamal Krishna Saha, Abhijit Mookerjee

We report here a study of the effect of short-ranged ordering on the electronic structure and optical properties of CuZn alloys. We shall use the augmented space recursion technique developed by us in conjunction with the tight-binding linear muffin tin orbitals basis.

Constantin R. Simovski

The reason of the non-locality of constitutive (material) parameters extracted in a usual way from the reflection-transmission coefficients of composite slab at moderately low frequencies is explained. The physical meaning of these parameters is clarified. Local constitutive parameters of metamaterial lattices are discussed and their existence at moderate fr

C. De Michele, P. Tartaglia, F. Sciortino

We report extensive Monte Carlo and event-driven molecular dynamics simulations of the fluid and liquid phase of a primitive model for silica recently introduced by Ford, Auerbach and Monson [J. Chem. Phys. 17, 8415 (2004)]. We evaluate the iso-diffusivity lines in the temperature-density plane to provide an indication of the shape of the glass transition li

N. P. Proukakis

The dependence of the three lowest order spatial correlation functions of a harmonically confined Bose gas on temperature and interaction strength is presented at equilibrium. Our analysis is based on a stochastic Langevin equation for the order parameter of a weakly-interacting gas. Comparison of the predicted first order correlation functions to those of a

G. Cifariello, E. Di Gennaro, G. Lamura, A. Andreone

We report a study of the temperature dependence of the surface resistance RS in the graphite intercalated compound (GIC) CaC6, where superconductivity at 11.5 K was recently discovered. Experiments are carried out using a copper dielectrically loaded cavity operating at 7 GHz in a "hot finger" configuration. Bulk CaC6 samples have been synthesized fr

A. Aziz, S. J. Bending, H. G. Roberts, S. Crampin

We exploit the ability to precisely control the magnetic domain structure of perpendicularly magnetized Pt/Co/Pt trilayers to fabricate artificial domain wall arrays and study their transport properties. The scaling behaviour of this model system confirms the intrinsic domain wall origin of the magnetoresistance, and systematic studies using domains patterne

Oleg A. Yeshchenko, Igor. M. Dmitruk, Andriy M. Dmytruk, Alexandr A. Alexeenko

Copper nanoparticles have been grown in silica matrix by annealing of the sol-gel prepared porous matrix impregnated with the copper nitrate. The annealing has been performed in air, successively in air and hydrogen, and in hydrogen. Cu nanoparticles in size range of 2-65 nm have been grown depending on annealing conditions. Annealing in air results in coppe

M. I. Katsnelson

Using the Landauer formula approach, it is proven that minimal conductivity of order of $e^{2}/h$ found experimentally in bilayer graphene is its intrinsic property. For the case of ideal crystals, the conductivity turns our to be equal to $e^{2}/2h$ per valley per spin. A zero-temperature shot noise in bilayer graphene is considered and the Fano factor is c

Csaba Toke, Jainendra K. Jain

It is demonstrated that an understanding of the 5/2 fractional quantum Hall effect can be achieved within the composite fermion theory without appealing to the Pfaffian wave function. The residual interaction between composite fermions plays a crucial role in establishing incompressibility at this filling factor. This approach has the advantage of being amen

I. Tikhonenkov, J. R. Anglin, A. Vardi

e formulate a method for studying the quantum field dynamics of ultracold Bose gases confined within optical lattice potentials, within the lowest Bloch-band Bose-Hubbard model. Our formalism extends the two-sites results of Phys. Rev. Lett. {\bf86}, 000568 (2001) to the general case of $M$ lattice sites. The methodology is based on mapping the Bose-Hubbard

Björn Michaelis

It is proposed to shoot a molecule through a pipe of mesoscopic scale. The molecule should effectifely carry two spins and antiferromagnetic chains should be embedded in the wall of the tube. If the momentum is detected before and behind the tube, a projection of the molecular spins s1 and s2 takes place. If the molecule did not loose momentum inside the tub

R. Di Capua, H. U. Aebersold, C. Ferdeghini, V. Ferrando

A series of MgB$_2$ thin films systematically disordered by neutron irradiation have been studied by Scanning Tunneling Spectroscopy. The c-axis orientation of the films allowed a reliable determination of local density of state of the $π$ band. With increasing disorder, the conductance peak moves towards higher voltages and becomes lower and broader, indica

Christoph Friedrich, Arno Schindlmayr, Stefan Blügel, Takao Kotani

This paper investigates the influence of the basis set on the GW self-energy correction in the full-potential linearized augmented-plane-wave (LAPW) approach and similar linearized all-electron methods. A systematic improvement is achieved by including local orbitals that are defined as second and higher energy derivatives of solutions to the radial scalar-r

R. J. Radwanski, Z. Ropka

We have calculated from first-principles the octupolar interactions of the Ni2+ ion in NiO, which gives the theoretical basis for the ionic description of properties of NiO with fully localized strongly-correlated eight d electrons. A failure of the up-now first principles ionic calculations for NiO was largely due to too small values taken for the octupolar

Simon E. Nigg, Rosa Lopez, Markus Buttiker

We consider charge relaxation in the mesoscopic equivalent of an RC circuit. For a single-channel, spin-polarized contact, self-consistent scattering theory predicts a universal charge relaxation resistance equal to half a resistance quantum independent of the transmission properties of the contact. This prediction is in good agreement with recent experiment

Xu Chang-Tan, Liang J-Q

Multi-high-frequency electron paramagnetic resonance(EPR) spectrum for a supermolecular dimer $[ Mn_4]_2$ of single-molecule magnets recently reported [S. Hill, R. S. Edwards, N. Aliaga-Alcalde and G. Christou(HEAC), Science 302, 1015 (2003)] is studied in terms of the perturbation method in which the high-order corrections to the level splittings of degener

Nianbei Li, Peiqing Tong, Baowen Li

We study heat conduction in one dimensional (1D) anharmonic lattices analytically and numerically by using an effective phonon theory. It is found that every effective phonon mode oscillates quasi-periodically. By weighting the power spectrum of the total heat flux in the Debye formula, we obtain a unified formalism that can explain anomalous heat conduction

Troels Markussen, Riccardo Rurali, Mads Brandbyge, Antti-Pekka Jauho

We calculate the resistance and mean free path in long metallic and semiconducting silicon nanowires (SiNWs) using two different numerical approaches: A real space Kubo method and a recursive Green's function method. We compare the two approaches and find that they are complementary: depending on the situation a preferable method can be identified. Sever

J. E. Lorenzo, C. Boullier, L. P. Regnault, U. Ammerahl

We have studied the spin anisotropy in spin-singlet ground state compounds and the magnetic chirality, as measured by inelastic polarized neutron scattering techniques, in the chain-sublattice of Sr14Cu24O41. In-plane and out of plane magnetic fluctuations are measured to be anisotropic and further discussed in the light of the current hypothesis of spin-orb

F. Simon, H. Kuzmany, B. Nafradi, T. Feher

C59N magnetic fullerenes were formed inside single-wall carbon nanotubes by vacuum annealing functionalized C59N molecules encapsulated inside the tubes. A hindered, anisotropic rotation of C59N was deduced from the temperature dependence of the electron spin resonance spectra near room temperature. Shortening of spin-lattice relaxation time, T_1, of C59N in

E. Nazarenko, J. E. Lorenzo, Y. Joly, J. L. Hodeau

Here we show that the low temperature phase of magnetite is associated with an effective, although fractional, ordering of the charge. Evidence and a quantitative evaluation of the atomic charges are achieved by using resonant x-ray diffraction (RXD) experiments whose results are further analyzed with the help of ab initio calculations of the scattering fact

Awnish Gupta, Gugang Chen, P. Joshi, S. Tadigadapa

Results of room temperature Raman scattering studies of ultrathin graphitic films supported on Si (111)/SiO2 substrates are reported. The results are significantly different from those known for graphite. Spectra were collected using 514 nm radiation on films containing from n=1 to 20 graphene layers, as determined by atomic force microscopy. Both the 1st an

Simon Foelling, Artur Widera, Torben Mueller, Fabrice Gerbier

We report on the direct observation of the transition from a compressible superfluid to an incompressible Mott insulator by recording the in-trap density distribution of a Bosonic quantum gas in an optical lattice. Using spatially selective microwave transitions and spin changing collisions, we are able to locally modify the spin state of the trapped quantum

Fei Liu, Zhong-can Ou-Yang

We present a general stochastic dynamic model of a cluster of biological complexes with fluctuating dissociation and association rates. The master equation has analytical solutions in two limiting cases: the vanishing force with reflecting boundary condition and slow reaction limit. In particular, the latter can describe the dynamics of a catch-slip bond clu

Pascal Crépey, Fabián P. Alvarez, Marc Barthélemy

We study numerically the variability of the outbreak of diseases on complex networks. We use a SI model to simulate the disease spreading at short times, in homogeneous and in scale-free networks. In both cases, we study the effect of initial conditions on the epidemic's dynamics and its variability. The results display a time regime during which the pre

Helmut G. Katzgraber, Mathias Koerner, A. P. Young

We study universality in three-dimensional Ising spin glasses by large-scale Monte Carlo simulations of the Edwards-Anderson Ising spin glass for several choices of bond distributions, with particular emphasis on Gaussian and bimodal interactions. A finite-size scaling analysis suggests that three-dimensional spin glasses obey universality.

J. P. Rodriguez

How the vortex lattice orders at long range in a layered superconductor with weak point pinning centers is studied through a duality analysis of the corresponding frustrated XY model. Vortex-glass order emerges out of the vortex liquid across a macroscopic number of weakly coupled layers in perpendicular magnetic field as the system cools down. Further, the

Martin Durant, Marten H. van Kerkwijk

The X-ray spectra of Anomalous X-ray Pulsars have long been fit by smooth, empirical models such as the sum of a black-body plus a power law. These reproduce the ~0.5 to 10 keV range well, but fail at lower and higher energies, grossly over-predicting the optical and under-predicting the hard X-ray emission. A poorly constrained source of uncertainty in dete

Falk Herwig, Bernd Freytag, Klaus Werner

The evolution of central stars of planetary nebulae can proceed in several distinct ways, either leading to H-deficiency or to H-normal surface composition. Several new simulations of the evolution channels that lead to H-deficiency are now available, mainly the born-again scenarios that are triggered by a He-shell flash during the hot pre-white dwarf evolut

Roeland P. van der Marel, David Schaller, Gijs Verdoes Kleijn

We have created a website, called "Black Holes: Gravity's Relentless Pull", which explains the physics and astronomy of black holes for a general audience. The site emphasizes user participation and is rich in animations and astronomical imagery. It won the top prize of the 2005 Pirelli INTERNETional Awards competition for the best communication of science a

J. M. Wrobel, L. C. Ho

The Seyfert 1 nucleus of NGC 4395 is energized by a black hole of 360,000 Solar masses (Peterson et al.), making it one of only two nuclear black holes of intermediate mass, one thousand to one million Solar masses, detected in the radio regime. Building upon UV and X-ray evidence for outflows from this Seyfert nucleus, the VLBI High Sensitivity Array was us

David W. Hogg, Morad Masjedi, Andreas A. Berlind, Michael R. Blanton

(abridged) There are good observational reasons to believe that the progenitors of red galaxies have undergone starbursts, followed by a post-starburst phase. We investigate the environments of post-starburst galaxies by measuring \textsl{(1)} number densities in $8 h^{-1} \mathrm{Mpc}$ radius comoving spheres, \textsl{(2)} transverse distances to nearest Vi

Martin C. Weisskopf, Douglas A. Swartz, Alberto Carraminana, Luis Carrasco

We report observations with the Chandra X-ray Observatory of a field in the gamma$-Cygni supernova remnant (SNR78.2+2.1) centered on the cataloged location of the unidentified, bright gamma-ray source 3EG J2020+4017. In this search for an X-ray counterpart to the gamma-ray source, we detected 30 X-ray sources. Of these, we found 17 strong-candidate counterpa

A. D. Biggs, R. J. Ivison

We present catalogues of faint 1.4-GHz radio sources from extremely-deep Very Large Array pointings in the Lockman Hole, the Hubble Deep Field North (HDF-N) and ELAIS N2. Our analysis of the HDF-N data has produced maps that are significantly deeper than those previously published and we have used these to search for counterparts to submm sources. For each o

Elena Amato, Pasquale Blasi

Particle acceleration at astrophysical shocks may be very efficient if magnetic scattering is self-generated by the same particles. This nonlinear process adds to the nonlinear modification of the shock due to the dynamical reaction of the accelerated particles on the shock. Building on a previous general solution of the problem of particle acceleration with

C. J. Poulton, J. S. Greaves, A. C. Cameron

The evidence for a rotation of the epsilon Eridani debris disc is examined. Data at 850 micron wavelength were previously obtained using the Submillimetre Common User Bolometer Array (SCUBA) over periods in 1997-1998 and 2000-2002. By chi-square fitting after shift and rotation operations, images from these two epochs were compared to recover proper motion a

F. Martins, B. Plez

The development of powerful infrared observational technics enables the study of very extincted objects and young embedded star forming regions. This is especially interesting in the context of massive stars which form and spend a non negligible fraction of their life still enshrouded in their parental molecular cloud. Spectrophotometric calibrations are thu

V. A. Marsakov, T. V. Borkova

We analyze the relations between the relative magnesium abundances, metallicities, and Galactic orbital elements for halo stars. We show that the relative magnesium abundances in protodisk halo stars are virtually independent of metallicity and lie within a fairly narrow range while presumably accreted stars demonstrate a large spread in relative magnesium a

Macarena Garcia-Marin, Luis Colina, Santiago Arribas, Almudena Alonso-Herrero

The luminous infrared galaxy Arp299 (IC694+NGC3690) is studied using optical integral field spectroscopy obtained with the INTEGRAL system, together with archival Hubble Space Telescope WFPC2 and NICMOS images. The stellar and ionized gas morphology shows lambda-dependent variations due to the combined effects of the dust internal extinction, and the nature

Adam Frank

We review work on the evolution of planetary nebulae and proto-planetaries via magneto-rotational mechanisms showing that a dynamo generated magnetic field can produce the energy and momentum needed to drive pPN and PNe outflows. Angular momentum considerations lead to the conclusion that single stars may not be capable of supporting strong fields for long t

Paul A. Crowther

Observational and theoretical evidence in support of metallicity dependent winds for Wolf-Rayet stars is considered. Well known differences in Wolf-Rayet subtype distributions in the Milky Way, LMC and SMC may be attributed to the sensitivity of subtypes to wind density. Implications for Wolf-Rayet stars at low metallicity include a hardening of ionizing flu

F. D'Antona, P. Ventura, L. Burderi, A. Teodorescu

In the hypothesis that the 5.4m binary RXJ0806.3+1527 consists of a low mass helium white dwarf (donor) transferring mass towards its more massive white dwarf companion (primary), we consider as possible donors white dwarfs which are the result of common envelope evolution occurring when the helium core mass of the progenitor giant was still very small (~ 0.

M. Matsuura, O. Chesneau, A. A. Zijlstra, W. Jaffe

We have observed the bipolar post-AGB candidate OH 231.8+4.2, using the mid-infrared interferometer MIDI and the infrared camera with the adaptive optics system NACO on the Very Large Telescope. An unresolved core (<200 mas in FWHM) is found at the center of the OH 231.8+4.2 in the 3.8 micron image. This compact source is resolved with the interferometer. We

M. Hetterscheidt, P. Simon, M. Schirmer, H. Hildebrandt

Aims. We present a cosmic shear analysis and data validation of 15 square degree high-quality R-band data of the Garching-Bonn Deep Survey obtained with the Wide Field Imager of the MPG/ESO 2.2m telescope. Methods. We measure the two-point shear correlation functions to calculate the aperture mass dispersion. Both statistics are used to perform the data qual

Joshua Pepper, B. Scott Gaudi

Radial velocity searches for extrasolar planets have recently detected several very low mass (7-20M_Earth) planets in close orbits with periods <10 days. We consider the prospects for detecting the analogs of these planets in Galactic open clusters via transits. We outline the requirements for constructing a transit survey that would allow one to probe such

R. B. A. Adamson, L. K. Shalm, A. M. Steinberg

Non-classical joint measurements can hugely improve the efficiency with which certain figures of merit of quantum systems are measured. We use such a measurement to determine a particular figure of merit, the purity, for a polarization qubit. In the process we highlight some of subtleties involved in common methods for generating decoherence in quantum optic

Gerardo Adesso

We investigate the correlation structure of pure N-mode Gaussian resources which can be experimentally generated by means of squeezers and beam splitters, whose entanglement properties are generic. We show that those states are specified (up to local unitaries) by N(N-1)/2 parameters, corresponding to the two-point correlations between any pair of modes. Our

Nicole F. Bell, Mikhail Gorchtein, Michael J. Ramsey-Musolf, Petr Vogel

We analyze the implications of neutrino masses for the magnitude of neutrino magnetic moments. By considering electroweak radiative corrections to the neutrino mass, we derive model-independent naturalness upper bounds on neutrino magnetic moments, $μ_ν$, generated by physics above the electroweak scale. For Dirac neutrinos, the bound is several orders of ma

Miguel Levy, Rong Li, Amir A. Jalali, Xiaoyue Huang

A study of band edge phenomena in ridge waveguide magnetophotonic crystals is presented. Normal mode analysis is used to examine the near-band edge and Bragg center-wavelength group velocities and their relation to the polarization. Large polarization departures from the input are observed in Bragg gratings patterned by focused-ion-beam milling on liquid-pha

J. Feist, A. Bäcker, R. Ketzmerick, S. Rotter

We investigate electronic quantum transport through nano-wires with one-sided surface roughness. A magnetic field perpendicular to the scattering region is shown to lead to exponentially diverging localization lengths in the quantum-to-classical crossover regime. This effect can be quantitatively accounted for by tunneling between the regular and the chaotic

Luca Chirolli, Guido Burkard

We study a voltage-controlled version of the superconducting flux qubit [Chiorescu et al., Science 299, 1869 (2003)] and show that full control of qubit rotations on the entire Bloch sphere can be achieved. Circuit graph theory is used to study a setup where voltage sources are attached to the two superconducting islands formed between the three Josephson ju

Irfan Chaudhary, Peter Hagelstein

Phonon exchange with nuclei in the course of fusion reactions that occur in a solid has not been analyzed previously. This problem has become of interest in connection with claims of observations of anomalies in metal deuterides. If the strong force interaction were dependent only on position (and not spin or isospin), then the coupling with phonons can be d

Maciej Niebrzydowski

We define new invariants of knots by means of quandle colorings and longitudinal information. These invariants can be applied to a tangle embedding problem and recognizing non-classical virtual knots.

Nikos Frantzikinakis

We find the smallest characteristic factor and a limit formula for the multiple ergodic averages associated to any family of three polynomials and polynomial families of the form $\{l_1p,l_2p,...,l_kp\}$. We then derive several multiple recurrence results and combinatorial implications, including an answer to a question of Brown, Graham, and Landman, and a g

Abraham Loeb

A fraction of the thermal protons in the outer envelope of an X-ray cluster have velocities that exceed the local escape speed from the cluster gravitational potential. The Coulomb mean-free-path of these protons is larger than the virial radius of the cluster at temperatures >2.5 keV. The resulting leakage of suprathermal particles generates a collisionless

S. Hussain, D. Marfatia, D. W. McKay, D. Seckel

We examine the dependence of event rates at neutrino telescopes on the neutrino-nucleon cross section for neutrinos with energy above 1 PeV, and contrast the results with those for cosmic ray experiments. Simple scaling of the Standard Model cross sections leaves the rates of upward events essentially unchanged. Details, such as detector depth and cross sect

Motoyuki Saijo, Eric Gourgoulhon

We investigate the viscosity driven instability in rotating relativistic stars by means of an iterative approach. We focus on polytropic rotating equilibrium stars and impose an m=2 perturbationin the lapse. We vary both the stiffness of the equation of state and the compactness of the star to study those effects on the value of the threshold. For a uniforml

D. A. Kann, N. Masetti, S. Klose

With a redshift of z=6.295, GRB 050904 is the most distant gamma-ray burst ever discovered. It was an energetic event at all wavelengths and the afterglow was observed in detail in the near-infrared bands. We gathered all available optical and NIR afterglow photometry of this GRB to construct a composite NIR light curve spanning several decades in time and f

Mohamed M. Anber, Lorenzo Sorbo

There is increasing interest in the role played by pseudo Nambu-Goldstone bosons (pNGBs) in the construction of string-inspired models of inflation. In these models the inflaton is expected to be coupled to gauge fields, and will lead to the generation of magnetic fields that can be of cosmological interest. We study the production of such fields mainly focu

Michael Kesden, Marc Kamionkowski

Satellite galaxies are tidally disrupted as they orbit the Milky Way. If dark matter (DM) experiences a stronger self-attraction than baryons, stars will preferentially gain rather than lose energy during tidal disruption leading to an enhancement in the trailing compared to the leading tidal stream. The Sgr dwarf galaxy is seen to have roughly equal streams

Lingfeng M. Zhang, Michael M. Fogler

We analyze electrostatic interaction between a sharp conducting tip and a thin one-dimensional wire, e.g., a carbon nanotube, in a scanned gate microscopy (SGM) experiment. The problem is analytically tractable if the wire resides on a thin dielectric substrate above a metallic backgate. The characteristic spatial scale of the electrostatic coupling to the t

Nestor Armesto, Jose D. Edelstein, Javier Mas

Following the nonperturbative prescription for the jet quenching parameter recently proposed by Liu, Rajagopal and Wiedemann, we compute the first correction in the inverse `t Hooft coupling corresponding to string alpha&#39; corrections in the dual background. We also consider the introduction of a chemical potential for the U(1)^3 gauged R-symmetry. While

Christopher J. Hillar, Troels Windfeldt

The study of graph vertex colorability from an algebraic perspective has introduced novel techniques and algorithms into the field. For instance, it is known that $k$-colorability of a graph $G$ is equivalent to the condition $1 \in I_{G,k}$ for a certain ideal $I_{G,k} \subseteq \k[x_1, ..., x_n]$. In this paper, we extend this result by proving a general d

Mark Stern

Using an elementary argument, we prove new fixed point theorems for classical elliptic complexes. We obtain new results for conformal relations and coisotropic intersections. We obtain theorems for the average intersections of families of special lagrangian and lagrangian varieties in certain homogeneous spaces.

Anton B. Vorontsov, Matthias J. Graf

We study the effects of Fermi-liquid interactions on quasi-two-dimensional d-wave superconductors in a magnetic field. The phase diagram of the superconducting state, including the periodic Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in high magnetic fields, is discussed for different strengths of quasiparticle many-body interactions within Landau&#39;s th

J. A. Nieto

We discuss different aspects of the 2+2-signature from the point of view of the quatl theory. In particular, we compare two alternative approaches to such a spacetime signature, namely the 1+1-matrix-brane and the 2+2-target spacetime of a string. This analysis also reveals hidden discrete symmetries of the 2+2-brane action associated with the 2+2-dimensiona

Kenneth Rines, Antonaldo Diaferio, Priyamvada Natarajan

We present a new determination of the cluster mass function and velocity dispersion function in a volume $\sim10^7 h^3$Mpc$^{-3}$ using the Fourth Data Release of the Sloan Digital Sky Survey (SDSS). We use the caustic technique to remove foreground and background galaxies. The cluster virial mass function agrees well with recent estimates from both X-ray ob

Yoshihide Tanaka, Akira Oguri, A. C. Hewson

Asymmetry in the Josephson couplings between two superconductors through a quantum dot is studied based on a single impurity Anderson model using the numerical renormalization group (NRG). Specifically, we examine how the difference between the couplings Γ_L and Γ_R affects the ground state, which is known to show a quantum phase transition between a nonmagn

Alexander Pechen, Nikolai Il&#39;in, Feng Shuang, Herschel Rabitz

A general scheme is presented for controlling quantum systems using evolution driven by non-selective von Neumann measurements, with or without an additional tailored electromagnetic field. As an example, a 2-level quantum system controlled by non-selective quantum measurements is considered. The control goal is to find optimal system observables such that c

D. Huertas-Hernando, F. Guinea, A. Brataas

A continuum model for the effective spin orbit interaction in graphene is derived from a tight-binding model which includes the $π$ and $σ$ bands. We analyze the combined effects of the intra-atomic spin-orbit coupling, curvature, and applied electric field, using perturbation theory. We recover the effective spin-orbit Hamiltonian derived recently from grou

Andras Vanyolos, Balazs Dora, Kazumi Maki, Attila Virosztek

We present a detailed theoretical study on the thermodynamic properties of impure quasi-one dimensional unconventional charge-, and spin-density waves in the framework of mean-field theory. The impurities are of the ordinary non-magnetic type. Making use of the full self-energy that takes into account all ladder-, and rainbow-type diagrams, we are able to ca

Julia Weber

We introduce the universal functorial equivariant Lefschetz invariant for endomorphisms of finite proper G-CW-complexes, where G is a discrete group. We use K_0 of the category of &#34;phi-endomorphisms of finitely generated free RPi(G,X)-modules&#34;. We derive results about fixed points of equivariant endomorphisms of cocompact proper smooth G-manifolds.

J E McMillan, C J Martoff

In the evaluation of novel scintillators, it is important to ensure that the spectrum of the light emitted by the scintillator is well matched to the response of the photomultiplier. In attempting to measure this spectrum using radioactive sources, it is found that so few photons are emitted per scintillation event that conventional spectroscopic techniques

Antony Lewis, Jochen Weller, Richard Battye

Details of how the primordial plasma recombined and how the universe later reionized are currently somewhat uncertain. This uncertainty can restrict the accuracy of cosmological parameter measurements from the Cosmic Microwave Background (CMB). More positively, future CMB data can be used to constrain the ionization history using observations. We first discu

N. Voglis, I. Stavropoulos, C. Kalapotharakos

Dissipationless N-body models of rotating galaxies, iso-energetic to a non-rotating model, are examined as regards the mass in regular and in chaotic motion. The values of their spin parameters $λ$ are near the value $λ=0.22$ of our Galaxy. We obtain the distinction between the sets of particles moving in regular and in chaotic orbits and we show that the sp

Ming Zhao, Tao Zhou, Bing-Hong Wang, Qing Ou

In this paper, inspired by the idea that the hub nodes of a highly heterogeneous network are not only the bottlenecks, but also effective controllers in the network synchronizing process, we bring forward an asymmetrical coupling method where the coupling strength of each node depends on its neighbors&#39; degrees. Compared with the uniform coupled method an

Fernando Izaurieta, Eduardo Rodríguez, Patricio Salgado

A new Lagrangian realizing the symmetry of the M Algebra in eleven-dimensional space-time is presented. By means of the novel technique of Abelian Semigroup Expansion, a link between the M Algebra and the orthosymplectic algebra osp(32|1) is established, and an M Algebra-invariant symmetric tensor of rank six is computed. This symmetric invariant tensor is a

J. C. Bueno Sanchez, K. Dimopoulos

We present a model for quintessential inflation using a string modulus for the inflaton - quintessence field. The scalar potential of our model is based on generic non-perturbative potentials arising in flux compactifications. We assume an enhanced symmetry point (ESP), which fixes the initial conditions for slow-roll inflation. When crossing the ESP the mod

Hovhannes M. Khudaverdian, Theodore Th. Voronov

We recall the main facts about the odd Laplacian acting on half-densities on an odd symplectic manifold and discuss a homological interpretation for it suggested recently by P. {\v{S}}evera. We study the relationship of odd symplectic geometry with classical objects. We show that the Berezinian of a canonical transformation for an odd symplectic form is a po

Alexey Andreanov, Alexandre Lefèvre

We study the non-equilibrium dynamics of the spherical p-spin models in the scaling regime near the plateau and derive the corresponding scaling functions for the correlators. Our main result is that the matching between different time regimes fixes the aging function in the aging regime to $h(t)=\exp(t^{1-μ})$. The exponent $μ$ is related to the one giving

A. Krizhanovsky

The program Synarcher for synonym (and related terms) search in the text corpus of special structure (Wikipedia) was developed. The results of the search are presented in the form of graph. It is possible to explore the graph and search for graph elements interactively. Adapted HITS algorithm for synonym search, program architecture, and program work evaluat