May 2002 arXiv papers — page 13

John F. Beacom, Will M. Farr, Petr Vogel

We propose that neutrino-proton elastic scattering, $ν+ p \to ν+ p$, can be used for the detection of supernova neutrinos in scintillator detectors. Though the proton recoil kinetic energy spectrum is soft, with $T_p \simeq 2 E_ν^2/M_p$, and the scintillation light output from slow, heavily ionizing protons is quenched, the yield above a realistic threshold

V. Berezinsky, M. Kachelriess, S. Ostapchenko

We study decays of superheavy particles $X$ into leptons. We show that they initiate cascades similar to QCD parton jets, if $m_X\gsim 10^6$ GeV. Electroweak cascading is studied and the energy spectra of the produced leptons are calculated in the framework of a broken SU(2) model of weak interactions. As application, important for the Z-burst model for ultr

Konstantin Goulianos

We present a study of $\bar pp$ collisions with a leading antiptoton and a rapidity gap in addition to that associated with the antiproton. The second gap is either within the region available to the proton dissociation products, $\bar p+p\to (\bar p+gap)+X+gap+Y$, or adjacent to the outgoing proton $\bar p+p\to (\bar p+gap)+X+(gap+p)$. Results are reported

Jose W. F. Valle

I review oscillation solutions to the neutrino anomalies and discuss how to account for the required pattern of neutrino masses and mixings from first principles. Unification and low-energy bottom-up approaches are discussed, the latter open up the possibility of testing neutrino mixing at high energy colliders, such as the LHC. Large \ne mixing is consisten

Jiri Hosek

We discuss two instances of anisotropic ordered quantum phases within QCD at finite baryon densities: (1) Fermionic deconfined three-color QCD matter with a spin one quark-quark Cooper pair condensate can exhibit distinct quantum i.e. low-temperature ($T$) behaviors on macroscopic scales which bona fide can be observed in neutron stars. (2) Bosonic confined

M. Buysse

We establish the existence of one-loop finite relations between the Cabibbo angle and the quark mass ratios, in the Standard Model with one Higgs doublet and two quark generations. Assuming a simple quark-lepton universality, we use the recent SNO results to predict the two-flavour mass spectrum of the neutrinos.

Alan Kostelecky, Matthew Mewes

An investigation is performed of the Lorentz-violating electrodynamics extracted from the renormalizable sector of the general Lorentz- and CPT-violating standard-model extension. Among the unconventional properties of radiation arising from Lorentz violation is birefringence of the vacuum. Limits on the dispersion of light produced by galactic and extragala

A. I. Studenikin

A review on the Lorentz invariant treatment of neutrino spin and flavour oscillations in moving and polarized matter is presented. Within this approach it becomes possible to consider neutrino oscillations in arbitrary electromagnetic fields. It is also shown that neutrino effective potential in matter can be significantly changed by relativistic motion of m

Yosuke Uehara

If TeV-scale gravity models are correct, the production of black holes will be the first signal of new physics. Once black holes are produced, they will give us much information about TeV-scale new physics directly. But such black holes can also be used for the precision measurements of the Standard Model (SM). The SM is nothing but a theory which can descri

D. T. Son

We consider relativistic superfluids where the U(1) baryon symmetry is spontaneously broken. Using the formalism of the quantum effective action, we show that the low-energy dynamics of the superfluid Goldstone boson is completely determined by the equation of state. Applying the general formalism to asymptotically high densities, we find the effective actio

Konstantin Goulianos

Results on soft and hard diffraction are briefly reviewed and placed in a QCD perspective using a parton model approach. Issues addressed include factorization, scaling properties, universality of rapidity gap formation, and unitarity. Predictions for differential cross sections of processes with multiple rapidity gaps are presented with examples for the Tev

Leonardo Patiño, Hernando Quevedo

We extend Dirac's approach about the quantization of the electric charge to the case of gravitational configurations. The spacetime curvature is used to define a phase-like object which allows us to extract information about the behavior of the corresponding spacetime. We show that all spacetimes that satisfy certain simple symmetry condition and for whi

Rafael A. Vera

Both from gravitational (G) experiments and from a new theoretical approach based on a particle model it is proved that the classical invariability of the bodies, after a change of relative rest-position with respect to other bodies, it is not true. The same holds for the traditional hypotheses based on the classical one. The new relationships are strictly l

Shu-Chiuan Chang, Robert Shrock

We present exact calculations of flow polynomials $F(G,q)$ for lattice strips of various fixed widths $L_y$ and arbitrarily great lengths $L_x$, with several different boundary conditions. Square, honeycomb, and triangular lattice strips are considered. We introduce the notion of flows per face $fl$ in the infinite-length limit. We study the zeros of $F(G,q)

Jorgen Vitting Andersen, Didier Sornette

We propose a payoff function extending Minority Games (MG) that captures the competition between agents to make money. In constrast with previous MG, the best strategies are not always targeting the minority but are shifting opportunistically between the minority and the majority. The emergent properties of the price dynamics and of the wealth of agents are

B. Jackson, E. Zaremba

We consider a model of a dilute Bose-Einstein condensed gas at finite temperatures, where the condensate coexists in a trap with a cloud of thermal excitations. Within the ZGN formalism, the dynamics of the condensate is described by a generalized Gross-Pitaevskii equation, while the thermal cloud is represented by a semiclassical kinetic equation. Our numer

A. D. Araujo, A. A. Moreira, H. A. Makse, H. E. Stanley

We study the distributions of traveling length l and minimal traveling time t through two-dimensional percolation porous media characterized by long-range spatial correlations. We model the dynamics of fluid displacement by the convective movement of tracer particles driven by a pressure difference between two fixed sites (''wells'') separate

M. J. Biercuk, M. C. Llaguno, M. Radosavljevic, J. K. Hyun

Single-wall carbon nanotubes (SWNTs) were used to augment the thermal transport properties of industrial epoxy. Samples loaded with 1 wt% unpurified SWNT material show a 70% increase in thermal conductivity at 40K, rising to 125% at room temperature; the enhancement due to 1 wt% loading of vapor grown carbon fibers is three times smaller. Electrical conducti

Andre Auto Moreira, Jose S. Andrade, Josue Mendes Filho, Stefano Zapperi

We investigate flux penetration in a disordered type II superconductor by molecular dynamics simulations of interacting vortices. We focus on the effect of different boundary conditions on the scaling laws for flux front propagation. The numerical results can be interpreted using a coarse grained description of the system in terms of a non-linear diffusion e

R. Roth, K. Burnett

The influence of disorder on ultracold atomic Bose gases in quasiperiodic optical lattices is discussed in the framework of the one-dimensional Bose-Hubbard model. It is shown that simple periodic modulations of the well depths generate a rich phase diagram consisting of superfluid, Mott insulator, Bose-glass and Anderson localized phases. The detailed evolu

Andre Auto Moreira, Jose Soares de Andrade, Luis A. Nunes Amaral

We investigate the statistics of the most connected nodes in scale-free networks. For a scale-free network model with homogeneous nodes, we show by means of extensive simulations that the exponential truncation--due to the finite size of the network--of the degree distribution governs the scaling of the extreme values. We also find that the distribution of m

M. Pissas, G. Kallias

We have studied the phase diagram of La$_{1-x}$Ca$_{x}$MnO$_{3}$ for $0.5\leq x\leq 0.9$ using neutron powder diffraction and magnetization measurements. At 300 K all samples are paramagnetic and single phase with crystallographic symmetry $Pnma$. As the temperature is reduced a structural transition is observed which is to a charge-ordered state only for ce

D. L. Yin, Z. Qi, H. Y. Xu, F. R. Wang

We present a microscopic derivation of the resistive transition equation for mixed state of superconductors. This form fits the experimental data of MgB2 with parameters in agreement with the prediction of BCS superconductivity. It also fits the experimental data of high quality untwined YBCO single crystal but with parameters somewhat different from the BCS

S. Soltanian, J. Horvat, X. L. Wang, M. Tomsic

In this letter, we report the results of transport Jc of solenoid coils upto 100 turns fabricated with Cu-sheathed MgB2 wires using a wind-reaction in-situ technique. Despite the low density of single core and some reaction between Mg and Cu-sheath, our results demonstrate the decrease in transport Jc with increasing length of MgB2 wires is insignificant. So

M. E. J. Newman

A network is said to show assortative mixing if the nodes in the network that have many connections tend to be connected to other nodes with many connections. We define a measure of assortative mixing for networks and use it to show that social networks are often assortatively mixed, but that technological and biological networks tend to be disassortative. W

Amit Acharya

Given a fine-scale physical theory characterized by an evolutionary system of equations and a set of quantities, defined from the variables of the fine theory, that serve as a coarse representation of the fine scale phenomena, a systematic method for developing an evolutionary set of equations for the coarse quantities is presented. This set may be considere

Amit Acharya

As a guide to constitutive specification, driving forces for dislocation velocity and nucleation rates are derived for a field theory of dislocation mechanics. A condition of closure for the theory in the form of a boundary condition for dislocation density is also derived. Kinematical features of dislocation evolution like initiation of bowing of a pinned s

Juan Pablo Fernandez, William J. Mullin

We study the Hartree-Fock-Bogoliubov mean-field theory as applied to a two-dimensional finite trapped Bose gas at low temperatures and find that, in the Hartree-Fock approximation, the system can be described either with or without the presence of a condensate; this is true in the thermodynamic limit as well. Of the two solutions, the one that includes a con

L. Wang, J. C. Wheeler, P. Hoeflich, A. Khokhlov

Extensive early observations proved that the ejecta of supernova 1987A (SN 1987A) are aspherical. Fifteen years after the supernova explosion, the Hubble Space Telescope has resolved the rapidly expanding ejecta. The late-time images and spectroscopy provide a geometrical picture that is consistent with early observations and suggests a highly structured, ax

M. Wold, M. Lacy, H. Dahle, P. B. Lilje

As a pilot study to investigate the distribution of matter in the fields of powerful AGN, we present weak lensing observations of deep fields centered on the radio-quiet quasar E1821 + 643, the radio galaxy 3C295, and the two radio-loud quasars, 3C334 and 3C254. The host clusters of E1821 + 643 and 3C295 are comfortably detected via their weak lensing signal

T. Treu, L. V. E. Koopmans

The Lenses Structure and Dynamics (LSD) Survey aims at measuring the luminous and dark matter distribution of high redshift early-type galaxies by combining gravitational lens analysis with newly determined velocity dispersion profiles. Here we describe the first results from the LSD survey, a measurement of the internal structure of the lens galaxy in MG201

L. L. Kiss, K. Szatmary

A detailed analysis of the century long visual light curve of the long-period Mira star R Cygni is presented and discussed. The data were collected from the publicly available databases of the AFOEV, the BAAVSS and the VSOLJ. The full light curve consists of 26655 individual points obtained between 1901 and 2001. The light curve and its periodicity were anal

Maxim Markevitch

This short technical note addresses a large discrepancy between the temperature profiles for the galaxy cluster A1835 derived by Schmidt et al. (2001) using Chandra and by Majerowicz et al. (2002) using XMM. The causes of this discrepancy may be instructive for the Chandra and XMM cluster analyses in general. The observation used by Schmidt et al. was affect

Tomislav Prokopec, Ola Tornkvist, Richard Woodard

We consider vacuum polarization from massless scalar electrodynamics in de Sitter inflation. The theory exhibits a 3+1 dimensional analogue of the Schwinger mechanism in which a photon mass is dynamically generated. The mechanism is generic for light scalar fields that couple minimally to gravity. The non-vanishing of the photon mass during inflation may res

Peter Goldreich, Nicole Rappaport

Recent HST images of the Saturnian satellites Prometheus and Pandora show that their longitudes deviate from predictions of ephemerides based on Voyager images. Currently Prometheus is lagging and Pandora leading these predictions by somewhat more than 20 degrees. We show that these discrepancies are fully accounted for by gravitational interactions between

S. Stanimirovic

While, in general, interferometers provide high spatial resolution for imaging small-scale structure (corresponding to high spatial frequencies in the Fourier plane), single-dishes can be used to image the largest spatial scales (corresponding to the lowest spatial frequencies), including the total power (corresponding to zero spatial frequency). For many as

Brenda C. Matthews, Christine D. Wilson

We present 850 micron polarimetry from the James Clerk Maxwell Telescope toward several dense cores within the dark cloud Barnard 1 in Perseus. Significant polarized emission is detected from across the mapped area and is not confined to the locations of bright cores. This indicates the presence of aligned grains and hence a component of the magnetic field i

S. Stanimirovic, J. M. Dickey, M. Krco, A. Brooks

We have mapped two regions at the northern tip of the Magellanic Stream in neutral hydrogen 21-cm emission using the Arecibo telescope. The new data are used to study the morphology and properties of the Stream far away from the Magellanic Clouds, as well as to provide indirect constraints on the properties of the Galactic Halo. We investigate confinement me

H. Schlattl, M. Salaris, S. Cassisi, A. Weiss

We investigate whether the observed high number of carbon- and nitrogen-enhanced extremely metal-poor stars could be explained by peculiar evolutionary properties during the core He flash at the tip of the red giant branch. For this purpose we compute a series of detailed stellar models expanding upon our previous work; in particular, we investigate if durin

S. Bottai, S. Giurgola

Tau neutrinos interacting inside the Earth produce $τ$ leptons which thereafter can decay inside the atmosphere. The propagation of extremely energetic \nut's and $τ$'s through the Earth is studied by means of a detailed Monte Carlo simulation, taking into account all major mechanisms of \nut interactions and $τ$ energy loss as well as decay modes. T

W. Bednarek, M. Giller, M. Zielinska

Recent analyses of the anisotropy of cosmic rays at $10^{18}$ eV (the AGASA and SUGAR data) show significant excesses from regions close to the Galactic Centre and Cygnus. Our aim is to check whether such anisotropies can be caused by single sources of charged particles. We investigate propagation of protons in two models of the Galactic regular magnetic fie

J. Grindlay, N. Gehrels, F. Harrison, R. Blandford

A next generation Gamma Ray Burst (GRB) mission to follow the upcoming Swift mission is described. The proposed Energetic X-ray Imaging Survey Telescope, EXIST, would yield the limiting (practical) GRB trigger sensitivity, broad-band spectral and temporal response, and spatial resolution over a wide field. It would provide high resolution spectra and locatio

C. S. Kochanek

Gravitational lens time delays depend on the Hubble constant, the observed image positions, and the surface mass density of the lens in the annulus between the images. Simple time delay lenses like PG1115+080, SBS1520+530, B1600+434, PKS1830-211 and HE2149-2745 have H0 = A(1-<k>)+B<k>(e-1) where the two coefficients A ~ 90km/s Mpc and B ~ 10km/s Mpc depend o

E. V. Mikheeva

Lambda-inflation is tested against CMB and LSS observational data. The constraints for inflationary parameters are considered.

Kandaswamy Subramanian, John D. Barrow

An inhomogeneous cosmological magnetic field creates vortical perturbations that survive Silk damping on much smaller scales than compressional modes. This ensures that there is no sharp cut-off in anisotropy on arc-minute scales. As we had pointed out earlier, tangled magnetic fields, if they exist, will then be a potentially important contributor to small-

H. C. Rosu, M. Planat

Micron-sized black holes do not necessarily have a constant horizon temperature distribution. The black hole remote-sensing problem means to find out the `surface&#39; temperature distribution of a small black hole from the spectral measurement of its (Hawking) grey pulse. This problem has been previously considered by Rosu, who used Chen&#39;s modified Moeb

M. Diehl

We study generalized parton distributions in the impact parameter representation, including the case of nonzero skewness xi. Using Lorentz invariance, and expressing parton distributions in terms of impact parameter dependent wave functions, we investigate in which way they simultaneously describe longitudinal and transverse structure of a fast moving hadron

P. Colin, V. Avila-Reese, O. Valenzuela, C. Firmani

We study the structure of Milky Way (MW)- and cluster-sized halos in a Lambda Cold Dark Matter (CDM) cosmology with self-interacting (SI) dark particles. The cross section per unit of particle mass has the form sigma = sig_0(1/v_100)^alpha, where sig_0 is a constant in units of cm^2/gr and v_100 is the relative velocity in units of 100 km/s. Different values

Phil Klein, Neal E. Young

We give a lower bound on the iteration complexity of a natural class of Lagrangean-relaxation algorithms for approximately solving packing/covering linear programs. We show that, given an input with $m$ random 0/1-constraints on $n$ variables, with high probability, any such algorithm requires $Ω(ρ\log(m)/ε^2)$ iterations to compute a $(1+ε)$-approximate sol

David Karger, Phil Klein, Cliff Stein, Mikkel Thorup

The multiway-cut problem is, given a weighted graph and k >= 2 terminal nodes, to find a minimum-weight set of edges whose removal separates all the terminals. The problem is NP-hard, and even NP-hard to approximate within 1+delta for some small delta > 0. Calinescu, Karloff, and Rabani (1998) gave an algorithm with performance guarantee 3/2-1/k, based on a

Otto C. W. Kong

The generic supersymmetric version of the Standard Model would have the minimal list of superfields incorporating the Standard Model particles, and a Lagrangian dictated by the Standard Model gauge symmetries. To be phenomenologically viable, soft supersymmetry breaking terms have to be included. In the most popular version of the supersymmetric Standard Mod

Evgeny I. Buchbinder, Ron Donagi, Burt A. Ovrut

We present a method for explicitly computing the non-perturbative superpotentials associated with the vector bundle moduli in heterotic superstrings and M-theory. This method is applicable to any stable, holomorphic vector bundle over an elliptically fibered Calabi-Yau threefold. For specificity, the vector bundle moduli superpotential, for a vector bundle w

Keshav Dasgupta, Mohammad M. Sheikh-Jabbari, Mark Van Raamsdonk

In this paper, we study the matrix model proposed by Berenstein, Maldacena, and Nastase to describe M-theory on the maximally supersymmetric pp-wave. We show that the model may be derived directly as a discretized theory of supermembranes in the pp-wave background, or alternatively, from the dynamics of D0-branes in type IIA string theory. We consider expand

Daniel D. Kelson, Ann I. Zabludoff, K. A. Williams, S. C. Trager

We have obtained deep, long-slit spectroscopy along the major axis of NGC 6166, the cD galaxy in the cluster Abell 2199, in order to measure the kinematics of intracluster starlight at large radii. The velocity dispersion rises beyond a few kpc, and steadily rises to 660 km/s at a radius of 60 kpc, nearly reaching the velocity dispersion of the cluster (775+

C. L. Garrido Alzar, M. Franca Santos, P. Nussenzveig

Using two different criteria for continuous variable systems we demonstrated that pump and probe beams became quantum correlated in a situation of Electromagnetically Induced Transparency in a sample of Rb atoms. Our result combines two important features for practical implementations in the field of quantum information processing. Namely, we proved the exis

Razmik G. Unanyan, Michael Fleischhauer, Nikolay V. Vitanov, Klaas Bergmann

We propose a technique for robust and efficient navigation in the Hilbert space of entangled symmetric states of a multiparticle system with externally controllable linear and nonlinear collective interactions. A linearly changing external field applied along the quantization axis creates a network of well separated level crossings in the energy diagram of t

Garry Bowen

Entanglement shared between the two ends of a quantum communication channel has been shown to be a useful resource in increasing both the quantum and classical capacities for these channels. The entanglement-assisted capacities were derived assuming an unlimited amount of shared entanglement per channel use. In this paper, bounds are derived on the minimum a

Irshadullah Khan

A theory of gravitation is presented. This theory does not relate gravitation to curvature of space-time. It explains the three standard results of general relativity in agreement with observations and suggests new experiments.

T. J. Humanic

Results from the data obtained in the first physics run of the Relativistic Heavy Ion Collider (RHIC) have shown suprisingly large elliptic flow and suprisingly small HBT radii. Attempts to explain both results in a consistant picture have so far been unsuccessful. The present work shows that a simple thermal-like initial state model coupled to a hadronic re

A. I. Titov, T. S. -H. Lee

We apply the effective Lagrangian approach to investigate the role of the nucleon resonances in $ω$ meson photoproduction at energies near the threshold. The resonant amplitudes are calculated from effective Lagrangians with the gamma NN* and omega NN* coupling constants fixed by the empirical helicity amplitudes and the vector meson dominance model. The con

P. G. Kevrekidis, B. A. Malomed, Yu. B. Gaididei

We study the existence and stability of localized states in the discrete nonlinear Schr{ö}dinger equation (DNLS) on two-dimensional non-square lattices. The model includes both the nearest-neighbor and long-range interactions. For the fundamental strongly localized soliton, the results depend on the coordination number, i.e., on the particular type of the la

G. Giachetta, L. Mangiarotti, G. Sardanashvily

We show that Jacobi fields of a completely integrable Hamiltonian system of m degrees of freedom also make up a completely integrable system. They provide m additional first integrals which characterize a relative motion.

Thomas C. Hales

By any account, the 1998 proof of the Kepler conjecture is complex. The thesis underlying this article is that the proof is complex because it is highly under-automated. Throughout that proof, manual procedures are used where automated ones would have been better suited. This article gives a series of nonlinear optimization algorithms and shows how a systema

Thomas C. Hales

This short note describes the tentative form of a finite-dimensional optimization problem that may be of use in a second-generation proof of the Kepler conjecture. In the original 1998 proof of the Kepler conjecture, the form of the optimization problem was constrained by limits to computer power and by the speed of the algorithms that were available in 1994

Eric S. Egge, Toufik Mansour

In 1990 West conjectured that there are $2(3n)!/((n+1)!(2n+1)!)$ two-stack sortable permutations on $n$ letters. This conjecture was proved analytically by Zeilberger in 1992. Later, Dulucq, Gire, and Guibert gave a combinatorial proof of this conjecture. In the present paper we study generating functions for the number of two-stack sortable permutations on

Daniel Liberzon

We study the recently introduced notion of output-input stability, which is a robust variant of the minimum-phase property for general smooth nonlinear control systems. The subject of this paper is developing the theory of output-input stability in the multi-input, multi-output setting. We show that output-input stability can be viewed as a combination of tw

Samir D. Mathur

The entropy and information puzzles arising from black holes cannot be resolved if quantum gravity effects remain confined to a microscopic scale. We use concrete computations in nonperturbative string theory to argue for three kinds of nonlocal effects that operate over macroscopic distances. These effects arise when we make a bound state of a large number

Horacio E. Camblong, Carlos R. Ordonez

A path-integral approach for delta-function potentials is presented. Particular attention is paid to the two-dimensional case, which illustrates the realization of a quantum anomaly for a scale invariant problem in quantum mechanics. Our treatment is based on an infinite summation of perturbation theory that captures the nonperturbative nature of the delta-f

M. Baker, R. Steinke

We show how an effective field theory of long distance QCD, describing a dual superconductor, can be expressed as an effective string theory of superconducting vortices. We evaluate the semiclassical expansion of this effective string theory about a classical rotating string solution in any spacetime dimension D. We show that, after renormalization, the zero

Michel Sorel

The unique constraints on neutrino oscillations which can be obtained by measuring the energy spectrum of supernova $\barν_e$&#39;s are first discussed. The focus is on 4-neutrino mass and mixing models capable of explaining the LSND evidence of $\barν_μ\to \barν_e$ oscillations. The potential of the Fermilab neutrino detector MiniBooNE to observe supernova

Yasunori Fujii, Akira Iwamoto, Tokio Fukahori, Toshihiko Ohnuki

We re-examined Shlyakhter&#39;s analysis of the Sm data in Oklo. With a special care of minimizing contamination due to the inflow of the isotope after the end of the reactor activity, we confirmed that his result on the time-variability of the fine-structure constant, $|\dotα/α|\lsim 10^{-17}{\rm y}^{-1}$, was basically correct. In addition to this upper bo

Olivier Sarbach, Manuel Tiglio

We present new many-parameter families of strongly and symmetric hyperbolic formulations of Einstein&#39;s equations that include quite general algebraic and live gauge conditions for the lapse. The first system that we present has 30 variables and incorporates an algebraic relationship between the lapse and the determinant of the three metric that generaliz

Vasu Alagar, Ralf Laemmel

A three-tiered specification approach is developed to formally specify collections of collaborating objects, say micro-architectures. (i) The structural properties to be maintained in the collaboration are specified in the lowest tier. (ii) The behaviour of the object methods in the classes is specified in the middle tier. (iii) The interaction of the object

G. L. Alfimov, P. G. Kevrekidis, V. V. Konotop, M. Salerno

In the present Letter we use the Wannier function basis to construct lattice approximations of the nonlinear Schrödinger equation with a periodic potential. We show that the nonlinear Schrödinger equation with a periodic potential is equivalent to a vector lattice with long-range interactions. For the case-example of the cosine potential we study the validit

L. Muehlbacher, R. Egger

The crossover from nonadiabatic to adiabatic electron transfer has been theoretically studied under a spin-boson model (dissipative two-state system) description. We present numerically exact data for the thermal transfer rate and the time-dependent occupation probabilities in largely unexplored regions of parameter space, using real-time path-integral Monte

O. S. Tarasov, A. P. Krekhov, L. Kramer

We consider the orientational instabilities, both homogeneous and spatially periodic, developing in a nematic liquid crystal under rectilinear oscillatory Couette flow for director alignment perpendicular to the flow plane. Using numerical and analytical approaches we determine the critical amplitude of oscillatory flow instabilities, the critical wave numbe

Shang Yuan Ren

Exact and general results on the electronic states in ideal free standing films are presented. In many interesting cases, such as in FCC (001) films and in FCC (110) films, the energies of most electronic states in the film can be analytically obained from the corresponding energy band structure of the bulk. This approach can be further extended to obtain ex

A. Trombettoni, A. Smerzi, A. R. Bishop

We study the discrete nonlinear Schrödinger equation (DNLS) in an annular geometry with on-site defects. The dynamics of a traveling plane-wave maps onto an effective &#39;&#39;non-rigid pendulum&#39;&#39; Hamiltonian. The different regimes include the complete reflection and refocusing of the initial wave, solitonic structures, and a superfluid state. In th

Jikeun Seo, S. -M. Kwon, H. -Y. Kim, J. -S. Kim

The steering effect on the growth of islands is investigated by combining molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations. Dynamics of depositing atoms and kinetics of atoms on a substrate are realized by MD and KMC, respectively. The reported experimental results on the asymmetric island growth [van Dijken {\it et al.}, Phys. Rev. Lett. {\

Torsten Andersen, W. Huebner

We compute the nonlinear optical response of an Fe monolayer placed on top of 1 to 4 monolayers of Cu(001). Our calculation is based on ab initio eigenstates of the slab, which are obtained within the full-potential linearized augmented plane-wave method. The ground-state spin-polarized electronic structure is converged self-consistently to an accuracy bette

Alexey Yamilov, Hui Cao

We study the formation of the photonic band structure in small clusters of dielectric spheres. The first signs of the band structure, an attribute of an infinite crystal, can appear for clusters of 5 particles. Density of resonant states of a cluster of 32 spheres may exhibit a well defined structure similar to the density of electromagnetic states of the in

G. C. McLaughlin, R. A. M. J. Wijers

Recently observed emission lines in the X-ray afterglow of gamma ray bursts suggest that iron group elements are either produced in the gamma ray burst, or are present nearby. If this material is the product of a thermonuclear burn, then such material would be expected to be rich in Nickel-56. If the nickel remains partially ionized, this prevents the electr

Yu. A. Shchekinov

Recent observations show the presence of metals in low-density Ly$α$ forest absorbers at high redshift ($z\sim 3$). It remains still far from being clearly understood what mechanisms spread metals over Mpc scales from the parent galaxies, whether metals are homogeneously distributed in the intergalactic medium (IGM), how metallicity of the IGM does evolve. T

Sunetra Giridhar, Aruna Goswami

We have undertaken a spectroscopic survey of field stars to find metal-poor objects among them. Observations are carried out using OMR spectrograph attached to 2.3m telescope at VBO Kavalur, India. The sample of candidate stars are chosen from prismatic survey of Beers and his collaborators covering a large part of the Galaxy. At the first phase of this proj

F. Larios, G. Tavares-Velasco, C. -P. Yuan

In a previous work we have shown that a general two-Higgs-doublet model (THDM) with a very light CP-odd scalar can be compatible with electroweak precision data, such as the rho parameter, BR(b --> s gamma), R_b, A_b, BR(Upsilon --> A gamma), BR(eta --> A gamma), and (g-2) of muon. Prompted by the recent significant change in the theoretical status of the la

Mordecai Golin, Claire Mathieu, Neal E. Young

We give a polynomial-time approximation scheme for the generalization of Huffman Coding in which codeword letters have non-uniform costs (as in Morse code, where the dash is twice as long as the dot). The algorithm computes a (1+epsilon)-approximate solution in time O(n + f(epsilon) log^3 n), where n is the input size.

Neal E. Young

The paper gives approximation algorithms for the k-medians and facility-location problems (both NP-hard). For k-medians, the algorithm returns a solution using at most ln(n+n/epsilon)k medians and having cost at most (1+epsilon) times the cost of the best solution that uses at most k medians. Here epsilon > 0 is an input to the algorithm. In comparison, the

Dietrich Bodeker

We study the Boltzmann-Langevin equation which describes the dynamics of hot Yang-Mills fields with typical momenta of order of the magnetic screening scale g^2 T. It is transformed into a path integral and Feynman rules are obtained. We find that the leading log Langevin equation can be systematically improved in a well behaved expansion in log(1/g)^-1. The

Andrew W. Steiner, Sanjay Reddy, Madappa Prakash

We investigate the consequences of enforcing local color neutrality on the color superconducting phases of quark matter by utilizing the Nambu-Jona-Lasinio model supplemented by diquark and the t&#39;Hooft six-fermion interactions. In neutrino free matter at zero temperature, color neutrality guarantees that the number densities of u, d, and s quarks in the

A. G. Smirnov

A new generalized formulation of the spectral condition is proposed for quantum fields with highly singular infrared behavior whose vacuum correlation functions are well defined only under smearing with analytic test functions in momentum space. The Euclidean formulation of QFT developed by Osterwalder and Schrader is extended to theories with infrared singu

M. Schechter, Y. Oreg, Y. Imry, Y. Levinson

We calculate the orbital linear magnetic response of disordered metallic rings to an Aharonov-Bohm flux using the BCS model for attractive electron-electron interaction. The contribution of all levels including those up to a high energy cutoff results in a much larger value than previously obtained using the local interaction model. The possible relevance of

Sugumi Kanno, Jiro Soda

A low energy iteration scheme to study nonlinear gravity in the brane world is developed. As a result, we obtain the brane world effective action at low energies. The relation between the geometrical approach and the approach using the AdS/CFT correspondence is also clarified. In particular, we find generalized dark radiation as homogeneous solutions in our

Lorenzo Iorio

The Lense-Thirring effect is currently being measured by means of a combination of the orbital residuals of the nodes of LAGEOS and LAGEOS II and the perigee of LAGEOS II. The total error is of the order of 20%. The most insidious systematic error is due to the mismodelled even zonal harmonics of the geopotential and amounts to 12.9%, according to EGM96 mode

Shin&#39;ichi Nojiri, Sergei D. Odintsov, Sachiko Ogushi

In the first part of this work we review the equations of motion for the brane presented in Friedmann-Robertson-Walker (FRW) form, when bulk is five-dimensional (A)dS Black Hole. The spacelike (timelike) FRW brane equations are considered from the point of view of their representation in the form similar to two-dimensional CFT entropy, so-called Cardy-Verlin

Naveen Garg, Neal E. Young

Congestion control in the current Internet is accomplished mainly by TCP/IP. To understand the macroscopic network behavior that results from TCP/IP and similar end-to-end protocols, one main analytic technique is to show that the the protocol maximizes some global objective function of the network traffic. Here we analyze a particular end-to-end, MIMD (mult

Hovhannes M. Khudaverdian, Theodore Voronov

We consider odd Laplace operators acting on densities of various weight on an odd Poisson (= Schouten) manifold $M$. We prove that the case of densities of weight 1/2 (half-densities) is distinguished by the existence of a unique odd Laplace operator depending only on a point of an ``orbit space&#39;&#39; of volume forms. This includes earlier results for od

Per Berglund, Andreas Brandhuber

We describe how chiral matter charged under SU(N) and SO(2N) gauge groups arises from codimension seven singularities in compactifications of M-theory on manifolds with G(2) holonomy. The geometry of these spaces is that of a cone over a six-dimensional Einstein space which can be constructed by (multiple) unfolding of hyper-Kahler quotient spaces. In type I

L. V. Gasparov, K. G. Brown, A. C. Wint, D. B. Tanner

The infrared reflectance of the transition metal chalcogenide 1T-TaS2 has been measured at temperatures from 30K to 360K over 30-45,000cm^-1 (4meV-5.5eV). The optical conductivity was obtained by Kramers-Kronig analysis. At 360K only modest traces of the phonon lines are noticeable. The phonon modes are followed by a pseudogap-like increase of the optical co

Stavros G. Kolliopoulos, Neal E. Young

Given matrices A and B and vectors a, b, c and d, all with non-negative entries, we consider the problem of computing min {c.x: x in Z^n_+, Ax > a, Bx < b, x < d}. We give a bicriteria-approximation algorithm that, given epsilon in (0, 1], finds a solution of cost O(ln(m)/epsilon^2) times optimal, meeting the covering constraints (Ax > a) and multiplicity co

L. F. Wei, S. Y. Liu, X. L. Lei

A simple alternative scheme for implementing quantum gates with a single trapped cold two-level ion beyond the Lamb-Dicke (LD) limit is proposed. Basing on the quantum dynamics for the laser-ion interaction described by a generalized Jaynes-Cummings model, one can introduce two kinds of elementary quantum operations i.e., the simple rotation on the bare atom