January 2006 arXiv papers — page 39

Christoph Weiss

Population transfer between two identical, communicating defects in a one-dimensional tight-binding lattice can be systematically controlled by external time-periodic forcing. Employing a force with slowly changing amplitude, the time it takes to transfer a particle from one defect to the other can be altered over several orders of magnitude. An analytical e

Ilya Molchanov

The paper suggests a generalisation of the diffusion-limited aggregation (DLA) based on using a general stochastic process to control particle movements before sticking to a growing cluster. This leads to models with variable characteristics that can provide a single framework for treating a number of earlier models of fractal growth: the DLA, the Eden model

N. Kristoffel

The physical origin of cuprate high-temperature superconductor pseudogaps remains debatable. We point out that the indication of such excitation is hidden in the usual expression for the quasiparticle energy. It can be realized on a suitable multiband spectrum with an interband pairing channel. The band components bearing the chemical potential manifest supe

J. Scola, A. Pautrat, C. Goupil, Ch. Simon

We report on critical currents and voltage noise measurements in Niobium strips in the superconducting state, in the presence of a bulk vortex lattice ($B < B_{C2}$) and in the surface superconducting state ($B_{c2}< B < B_{C3}$). For homogeneous surfaces, the correlation length of the current fluctuations can be associated with the electromagnetic skin dept

Y. Kopelevich, J. C. Medina Pantoja, R. R. da Silva, S. Moehlecke

Applied magnetic field induces metal - insulator and re-entrant insulator-metal transitions in both graphite and rhombohedral bismuth. The corresponding transition boundaries plotted on the magnetic field - temperature (B - T) plane nearly coincide for these semimetals and can be best described by power laws T ~ (B - B_c)^k, where B_c is a critical field at

K. Siemensmeyer, K. Flachbart, S. Gabani, S. Matas

Neutron scattering experiments on frustrated fcc - antiferromagnet HoB$_{12}$ have been performed above T$_{N}$ = 7.4 K. Diffuse scattering patterns indicate that above Neel temperature correlations between neighboring magnetic moments of Ho - ions appear, similar to the appearance of coupled spin-pairs (dimers) in low dimensional magnets. Moreover, the diff

C. Nowak, T. A. Vilgis

The behaviour of rod-coil diblock copolymers close to a surface is discussed by using extended scaling methods. The copolymers are immersed in selective solvent such that the rods are likely to aggregate to gain energy. The rods are assumed to align only parallel to each other, such that they gain a maximum energy by forming liquid crystalline structures. If

Yue Yu, S. T. Chui

We show that the electron-like and photon-like excitations may exist in a three-dimensional Bose-Fermi Hubbard model describing ultracold Bose-Fermi atom mixtures in optical lattices. In a Mott insulating phase of the Bose atoms, these excitations are stabilized by an induced repulsive interaction between &#39;electrons&#39; if the Fermi atoms are nearly hal

Takeshi Nishimatsu, Umesh V. Waghmare, Yoshiyuki Kawazoe, Benjamin Burton

We report a simple safe and attractive pedagogic demonstration with magnetic compasses that facilitates an intuitive understanding of the concept that ferromagnetism and ferroelectricity do not result from dipole-dipole interactions alone. Phonon dispersion relations were calculated for a 3-dimensional simple-cubic dipole crystal and a 2-dimensional square-l

A. Malakis, S. S. Martinos, I. A. Hadjiagapiou, N. G. Fytas

Dominant energy subspaces of statistical systems are defined with the help of restrictive conditions on various characteristics of the energy distribution, such as the probability density and the forth order Binder&#39;s cumulant. Our analysis generalizes the ideas of the critical minimum energy-subspace (CrMES) technique \cite{malakis04}, applied previously

Stefan Hollos, Richard Hollos

We derive formulas for the matrix elements of the two dimensional square lattice Green function along the diagonal, and along the coordinate axes. We also give an asymptotic formula for the diagonal elements.

M. Köhl, Th. Busch, K. Molmer, T. W. Hänsch

We report on an investigation of the beam profile of an atom laser extracted from a magnetically trapped $^{87}$Rb Bose-Einstein condensate. The transverse momentum distribution is magnified by a curved mirror for matter waves and a momentum resolution of 1/60 of a photon recoil is obtained. We find the transverse momentum distribution to be determined by th

Lorenz Bartosch, Leon Balents, Subir Sachdev

We explore the experimental implications of a recent theory of the quantum dynamics of vortices in superfluids proximate to Mott insulators (cond-mat/0408329 and cond-mat/0409470). The theory predicts modulations in the local density of states in the regions over which the vortices execute their quantum zero point motion. We use the spatial extent of such mo

Dmitry S. Novikov

A periodic potential applied to a nanotube is shown to lock electrons into incompressible states that can form a devil&#39;s staircase. Electron interactions result in spectral gaps when the electron density (relative to a half-filled Carbon pi-band) is a rational number per potential period, in contrast to the single-particle case where only the integer-den

M. Paulsson

Non equilibrium Green&#39;s function methods are regularly used to calculate current and charge densities in nanoscale (both molecular and semiconductor) conductors under bias. This method is mainly used for ballistic conduction but may be extended to include inelastic scattering. In this tutorial paper the NEGF equations for the current and charge density m

Beth A. Biller, Laird M. Close, Elena Masciadri, Rainer Lenzen

We discuss the preliminary results of a survey of young (<300 Myr), close (<50 pc) stars with the Simultaneous Differential Extrasolar Planet Imager (SDI) implemented at the VLT and the MMT. SDI uses a double Wollaston prism and a quad filter to take 4 identical images simultaneously at 3 wavelengths surrounding the 1.62 um methane bandhead found in the spec

H. I. Teplitz, L. Armus, B. T. Soifer, V. Charmandaris

We present the first MIR spectrum of the z=2.2856 ultraluminous, infrared galaxy FSC 10214+4724, obtained with the Infrared Spectrograph onboard the Spitzer Space Telescope. The spectrum spans a rest wavelength range of 2.3-11.5 microns, covering a number of key diagnostic emission and absorption features. The most prominent feature in the IRS spectrum is th

Beth A. Biller, Laird M. Close, Rainer Lenzen, Wolfgang Brandner

We discuss the instrumental and data reduction techniques used to suppress speckle noise with the Simultaneous Differential Imager (SDI) implemented at the VLT and the MMT. SDI uses a double Wollaston prism and a quad filter to take 4 identical images simultaneously at 3 wavelengths surrounding the 1.62 um methane bandhead found in the spectrum of cool brown

J. Horak, V. Karas

Two inter-related peaks occur in high-frequency power spectra of X-ray lightcurves of several black-hole candidates. We further explore the idea that a non-linear resonance mechanism, operating in strong-gravity regime, is responsible for these quasi-periodic oscillations (QPOs). By extending the multiple-scales analysis of Rebusco, we construct two-dimensio

James L. Crooks, Paul H. Frampton

A cosmological theory that predicts a late-time accelerated attractor with a constant dark matter to dark energy ratio can be said to solve the Coincidence Problem. Such cosmologies are naturally generated in the context of non-standard gravity theories under conformal transformation because of the resulting couplings between scalar fields and matter. The pr

E. Masana, C. Jordi, I. Ribas

This paper presents a method to determine effective temperatures, angular semi-diameters and bolometric corrections for population I and II FGK type stars based on V and 2MASS IR photometry. Accurate calibration is accomplished by using a sample of solar analogues, whose average temperature is assumed to be equal to the solar effective temperature of 5777 K.

David Branch, Leeann Chau Dang, Nicholas Hall, Wesley Ketchum

A comparative study of near-maximum-light optical spectra of 24 Type Ia supernovae (SNe Ia) is presented. The spectra are quantified in two ways, and assigned to four groups. Seven &#34;core-normal&#34; SNe Ia have very similar spectra, except for strong high-velocity CaII absorption in SN 2001el. Seven SNe Ia are assigned to a &#34;broad-line&#34; group, th

John Krizmanic, Gerry Skinner, Neil Gehrels

The employment of a large area Phase Fresnel Lens (PFL) in a gamma-ray telescope offers the potential to image astrophysical phenomena with micro-arcsecond angular resolution. In order to assess the feasibility of this concept, two detailed studies have been conducted of formation flying missions in which a Fresnel lens capable of focussing gamma-rays and th

C. Tappert, B. T. Gaensicke, R. E. Mennickent, L. Schmidtobreick

We present preliminary results on spectroscopic data of the candidate pre-cataclysmic variable LTT 560. A fit to the flux-calibrated spectrum reveals the temperature of the white-dwarf primary to be T_eff = 7000 - 7500 K, and confirms the result of previous studies on the detection of an M5V secondary star. The analysis of radial velocity data from spectral

C. G. Bassa, P. G. Jonker, J. J. M. in &#39;t Zand, F. Verbunt

We present the identification of the optical counterparts to the low-mass X-ray binaries 1A 1246-588 and 4U 1812-12. We determine the X-ray position of 1A 1246-588 from ROSAT/PSPC observations and find within the error circle a blue star with V=19.45, B-V=0.22 and R-I=0.22 which we identify as the counterpart. Within the Chandra error circle of 4U 1812-12, a

Tristan Guillot, Ricardo Hueso

It has been proposed that the enrichment in noble gases found by Galileo in Jupiter&#39;s atmosphere can be explained by their delivery inside cold planetesimals. We propose instead that this is a sign that the planet formed in a chemically evolved disk and that noble gases were acquired mostly in gaseous form during the planet&#39;s envelope capture phase.

J. Hwang, H. Noh

Except for the presence of gravitational wave source term, the relativistic perturbation equations of a zero-pressure irrotational fluid in a flat Friedmann world model coincide exactly with the Newtonian ones to the second order in perturbations. Such a relativistic-Newtonian correspondence is available in a special gauge condition (the comoving gauge) in w

L. -S. The, D. D. Clayton, R. Diehl, D. H. Hartmann

According to standard models supernovae produce radioactive $^{44}$Ti, which should be visible in gamma-rays following decay to $^{44}$Ca for a few centuries. $^{44}Ti production is believed to be the source of cosmic $^{44}$Ca, whose abundance is well established. Yet, gamma-ray telescopes have not seen the expected young remnants of core collapse events. T

Julien Berestycki, Nathanaël Berestycki, Jason Schweinsberg

For a finite measure $\varLambda$ on $[0,1]$, the $\varLambda$-coalescent is a coalescent process such that, whenever there are $b$ clusters, each $k$-tuple of clusters merges into one at rate $\int_0^1x^{k-2}(1-x)^{b-k}\varLambda(\mathrm{d}x)$. It has recently been shown that if $1<α<2$, the $\varLambda$-coalescent in which $\varLambda$ is the $\operatornam

R. L. Oldershaw

Within the context of a fractal paradigm that emphasizes nature&#39;s well-stratified hierarchical organization, the delta Scuti class of variable stars is investigated for evidence of discrete cosmological self-similarity. Methods that were successfully applied to the RR Lyrae class of variable stars are used to identify Atomic Scale analogues to delta Scut

Oded Kenneth, Israel Klich

We consider the Casimir interaction between (non-magnetic) dielectric bodies or conductors. Our main result is a proof that the Casimir force between two bodies related by reflection is always attractive, independent of the exact form of the bodies or dielectric properties. Apart from being a fundamental property of fields, the theorem and its corollaries al

K. Schawinski, S. Kaviraj, S. Khochfar, S. -J. Yoon

We use \textit{GALEX} (Galaxy Evolution Explorer) near-UV (NUV) photometry of a sample of early-type galaxies selected in \textit{SDSS} (Sloan Digital Sky Survey) to study the UV color-magnitude relation (CMR). $NUV-r$ color is an excellent tracer of even small amounts ($\sim 1$% mass fraction) of recent ($\la 1$ Gyr) star formation and so the $NUV-r$ CMR al

S. Alekhin, G. Altarelli, N. Amapane, J. Andersen

The HERA electron--proton collider has collected 100 pb$^{-1}$ of data since its start-up in 1992, and recently moved into a high-luminosity operation mode, with upgraded detectors, aiming to increase the total integrated luminosity per experiment to more than 500 pb$^{-1}$. HERA has been a machine of excellence for the study of QCD and the structure of the

S. Kaviraj, K. Schawinski, J. E. G. Devriendt, I. Ferreras

We have studied ~2100 early-type galaxies in the SDSS DR3 which have been detected by the GALEX Medium Imaging Survey (MIS), in the redshift range 0 < z < 0.11. Combining GALEX UV photometry with corollary optical data from the SDSS, we find that, at a 95 percent confidence level, at least ~30 percent of galaxies in this sample have UV to optical colours con

Qian Niu, Iacopo Carusotto, A. B. Kuklov

We consider critical space-time correlations in trapped utracold atoms and propose a method for their detection by the interference with a reference Bose-Einstein condensate. An important information about universal properties can be obtained despite non-uniformity and small sizes of atomic clouds. The advantage of this method is that the correlation propert

A. Franceschini, G. Rodighiero, P. Cassata, S. Berta

We constrain the evolution of the galaxy mass and luminosity functions from the analysis of (public) multi-wavelength data in the Chandra Deep Field South (CDFS) area, obtained from the GOODS and other projects, and including very deep high-resolution imaging by HST/ACS. Our reference catalogue of faint high-redshift galaxies, which we have thoroughly tested

Wolfgang Mulzer, Guenter Rote

A triangulation of a planar point set S is a maximal plane straight-line graph with vertex set S. In the minimum-weight triangulation (MWT) problem, we are looking for a triangulation of a given point set that minimizes the sum of the edge lengths. We prove that the decision version of this problem is NP-hard. We use a reduction from PLANAR-1-IN-3-SAT. The c

Yair Rezek, Ronnie Kosloff

The unavoidable irreversible losses of power in a heat engine are found to be of quantum origin. Following thermodynamic tradition a model quantum heat engine operating by the Otto cycle is analyzed. The working medium of the model is composed of an ensemble of harmonic oscillators. A link is established between the quantum observables and thermodynamical va

M. Rovinsky

Let $G$ be the automorphism group of an extension $F|k$ of algebraically closed fields of characteristic zero and of transcendence degree $n$, $1\le n\le\infty$. In this paper we (i) construct some maximal closed non-open subgroups $G_v$, and some (all, in the case of countable transcendence degree) maximal open proper subgroups of $G$; (ii) describe, in the

Nima Arkani-Hamed, Lubos Motl, Alberto Nicolis, Cumrun Vafa

We conjecture a general upper bound on the strength of gravity relative to gauge forces in quantum gravity. This implies, in particular, that in a four-dimensional theory with gravity and a U(1) gauge field with gauge coupling g, there is a new ultraviolet scale Lambda=g M_{Pl}, invisible to the low-energy effective field theorist, which sets a cutoff on the

Jens Oehlschlägel

Data-based classification is fundamental to most branches of science. While recent years have brought enormous progress in various areas of statistical computing and clustering, some general challenges in clustering remain: model selection, robustness, and scalability to large datasets. We consider the important problem of deciding on the optimal number of c

J. F. Gomes, L. H. Ymai, A. H. Zimerman

The introduction of defects is discussed under the Lagrangian formalism and Backlund transformations for the N=1 super sinh-Gordon model. Modified conserved momentum and energy are constructed for this case. Some explicit examples of different Backlund solitons solutions are discussed. The Lax formulation within the space split by the defect leads to the int

Tobias Kretz, Marko Woelki, Michael Schreckenberg

&#34;Oscillations&#34; occur in quite different kinds of many-particle-systems when two groups of particles with different directions of motion meet or intersect at a certain spot. We present a model of pedestrian motion that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis&#39; correlated random walk are s

S. A. Zvyagin, J. Wosnitza, J. Krzystek, R. Stern

BaCuSi$_2$O$_6$, a $S=1/2$ quantum antiferromagnet with a double-layer structure of Cu$^{2+}$ ions in a distorted planar-rectangular coordination and with a dimerized spin singlet ground state, is studied by means of the electron paramagnetic resonance technique. It is argued that multiple absorptions observed at low temperatures are intimately related to a

Ivan V. Losev

In this paper we deal with a Hamiltonian action of a reductive algebraic group $G$ on an irreducible normal affine Poisson variety $X$. We study the invariant moment map $ψ_{G,X}:X\to \g$, that is, the composition of the moment map $μ_{G,X}:X\to g:=Lie(G)$ and the quotient morphism $g\to g\quo G$. We obtain some results on the dimensions of fibers of $ψ_{G,X

Kwankyu Lee, Michael E. O&#39;Sullivan

The interpolation step of Guruswami and Sudan&#39;s list decoding of Reed-Solomon codes poses the problem of finding the minimal polynomial of an ideal with respect to a certain monomial order. An efficient algorithm that solves the problem is presented based on the theory of Groebner bases of modules. In a special case, this algorithm reduces to a simple Be

Natasha Harrell, Sam Nelson

Non-classical virtual knots may have non-isomorphic upper and lower quandles. We exploit this property to define the quandle difference invariant, which can detect non-classicality by comparing the numbers of homomorphisms into a finite quandle from a virtual knot&#39;s upper and lower quandles. The invariants for small-order finite quandles detect non-class

Tieyan Si

Phase transition is a war game. It widely exists in different kinds of complex system beyond physics. Where there is revolution, there is phase transition. The renormalization group transformation, which was proved to be a powerful tool to study the critical phenomena, is actually a game process. The phase boundary between the old phase and new phase is the

Yuri Levin

Quasi-Periodic Oscillations (QPOs) have been observed during three powerful magnetar flares, from SGR0526-66, SGR1806-20 and SGR1900+14. These QPOs have been commonly interpreted as being driven by the mechanical modes of the magnetar&#39;s solid crust which are excited during the flare. Here we show that this interpretation is in sharp contradiction with th

Tadafumi Ohsaku

We investigate the phenomena of the dynamical chiral symmetry breaking (DCSB), color superconductivity (CSC), and Bose-Einstein condensation (BEC) in an ${\cal N}=1$ four-dimensional generalized SUSY Nambu$-$Jona-Lasinio model at finite temperature and density. Both the ${\cal N}=1$ four-dimensional and ${\cal N}=2$ three-dimensional cases are considered. Th

J. Kiukas, P. Lahti, K. Ylinen

We consider questions related to a quantization scheme in which a classical variable f:Ω\to R on a phase space Ωis associated with a semispectral measure E^f, such that the moment operators of E^f are required to be of the form Γ(f^k), with Γa suitable mapping from the set of classical variables to the set of (not necessarily bounded) operators in some Hilbe

V. P. Maslov

The notion of density of a finite set is introduced. We prove a general theorem of set theory which refines the Gibbs, Bose--Einstein, and Pareto distributions as well as the Zipf law.

V. N. Smelyanskiy, D. G. Luchinsky, M. Millons

The problem of determining dynamical models and trajectories that describe observed time-series data allowing for the understanding, prediction and possibly control of complex systems in nature is of a great interest in a wide variety of fields. Often, however, only part of the system&#39;s dynamical variables can be measured, the measurements are corrupted

A. Johansen, I. Simonsen, M. H. Jensen

The inverse statistics is the distribution of waiting times needed to achieve a predefined level of return obtained from (detrended) historic asset prices \cite{optihori,gainloss}. Such a distribution typically goes through a maximum at a time coined the {\em optimal investment horizon}, $τ^*_ρ$, which defines the most likely waiting time for obtaining a giv

David Sundkvist

We present a new unified covariant description of electromagnetic field properties for an arbitrary space-time. We derive a complete set of irreducible components describing a six-dimensional electromagnetic field from the Maxwell and metric tensors using the symmetry group SL(2,C). For the special case of a flat space-time metric the components are shown to

Ching-Chuan Su

The Compton effect is commonly cited as a demonstration of the particle feature of light, while the wave nature of matter has been proposed by de Broglie and demonstrated by Davisson and Germer with the Bragg diffraction of electron beams. In this investigation, we present an entirely different interpretation of the Compton effect based on the postulates of

A. Sulaksono, C. K. Williams, P. T. P. Hutauruk, T. Mart

The sensitivity of the differential cross section of the interaction between neutrino-electron with dense matter to the possibly nonzero neutrino electromagnetic properties has been investigated. Here, the relativistic mean field model inspired by effective field theory has been used to describe non strange dense matter, both with and without the neutrino tr

Lauss Bernhard

The NPDGamma experiment at the Los Alamos Neutron Science Center (LANSCE) is dedicated to measure with high precision the parity violating asymmetry in the $γ$ emission after capture of spin polarized cold neutrons in para-hydrogen. The measurement will determine unambiguously the weak pion-nucleon-nucleon ($πNN$) coupling constant {\it f$^1_π$}

Daniela Rohe

The experiment E97-006 was performed at Jefferson Lab to measure the momentum and energy distribution of protons in the nucleus far from the region of the (approximate) validity of the mean field description, i.e. at high momentum and energies. The occurrence of this strength is long known from occupation numbers less than one. In the experiment reported her

Christian Fleischhack

We present a construction method for mappings between generalized connections, comprising, e.g., the action of gauge transformations, diffeomorphisms and Weyl transformations. Moreover, criteria for continuity and measure preservation are stated.

Y. Brihaye, J. Ndimubandi, B. Prasad Mandal

Let us denote ${\cal V}$, the finite dimensional vector spaces of functions of the form $ψ(x) = p_n(x) + f(x) p_m(x)$ where $p_n(x)$ and $p_m(x)$ are arbitrary polynomials of degree at most $n$ and $m$ in the variable $x$ while $f(x)$ represents a fixed function of $x$. Conditions on $m,n$ and $f(x)$ are found such that families of linear differential operat

J. Kiukas

It is shown that the characterization of covariant positive operator measures on nonunimodular locally compact groups can be obtained by using vector measure theoretic methods, without an application of Mackey&#39;s imprimitivity theorem.

Norbert Roehrl

We introduce a variational algorithm, which solves the classical inverse Sturm-Liouville problem when two spectra are given. In contrast to other approaches, it recovers the potential as well as the boundary conditions without a priori knowledge of the mean of the potential. Numerical examples show that the algorithm works quite reliable, even in the presenc

Davide Catania

We consider radial solutions to the Cauchy problem for the linear wave equation with a small short-range electromagnetic potential (the &#34;square version&#34; of the massless Dirac equation with a potential) and zero initial data. We prove two a priori estimates that imply, in particular, a dispersive estimate.

Richard F. Bass, Alexander Lavrentiev

We consider the degenerate elliptic operator acting on $C^2$ functions on $[0,\infty)^d$: \[ L f(x)=\sum_{i=1}^d a_i(x) x_i^{α_i} \frac{\partial^2 f}{\partial x_i^2} (x) +\sum_{i=1}^d b_i(x) \frac{\partial f}{\partial x_i}(x), \] where the $a_i$ are continuous functions that are bounded above and below by positive constants, the $b_i$ are bounded and measura

Hao Pan

Let n>=3 be an odd integer. For any integer a prime to n, define the permutation gamma_{a,n} of {1,...,(n-1)/2} by gamma_{a,n}(x)=n-\dec{ax}_n if {ax}_n>=(n+1)/2, and {ax}_n if {ax}_n<=(n-1)/2, where {x}_n denotes the least nonnegative residue of x modulo n. In this note, we show that the sign of gamma_{a,n} coincides with the Jacobi symbol (a/n) if n=1 mod

Eitan Bachmat

We consider the problem of estimating the average tour length of the asymmetric TSP arising from the disk scheduling problem with a linear seek function and a probability distribution on the location of I/O requests. The optimal disk scheduling algorithm of Andrews, Bender and Zhang is interpreted as a simple peeling process on points in a 2 dimensional spac

Erik Christensen, Cristina Ivan

We study countable sums of two dimensional modules for the continuous complex functions on a compact metric space and show that it is possible to construct a spectral triple which gives the original metric back. This spectral triple will be finitely summable for any positive parameter. We also construct a sum of two dimensional modules which reflects some as

Gady Kozma, Ferenc Oravecz

We show that for every finite symetric set S of integer vectors, every real trigonometric polynomial on the d dimensional torus with spectrum in S has a zero in every closed ball of diameter D, where D is the sum over S of 1 over 4 times the L2 norm of the vector. We investigate tightness in some special cases.

Ilia Ponomarenko, A. Rahnamai Barghi

An amorphic association scheme has the property that any of its fusion is also an association scheme. In this paper we generalize the property to be amorphic to an arbitrary C-algebra and prove that any amorphic C-algebra is determined up to isomorphism by the multiset of its degrees and an additional integer equal 1 or -1. Moreover, we show that any amorphi

M. J. D. Hamilton, D. Kotschick

We prove that all minimal symplectic four-manifolds are essentially irreducible. We also clarify the relationship between holomorphic and symplectic minimality of Kähler surfaces. This leads to a new proof of the deformation-invariance of holomorphic minimality for complex surfaces with even first Betti number which are not Hirzebruch surfaces.

W. Chen, H. Lu, C. N. Pope

The four-dimensional Kerr-de Sitter and Kerr-AdS black hole metrics have cohomogeneity 2, and they admit a generalisation in which an additional parameter characterising a NUT charge is included. In this paper, we study the higher-dimensional Kerr-AdS metrics, specialised to cohomogeneity 2 by appropriate restrictions on their rotation parameters, and we sho

Probir Roy

Neutrino factfile and $D \equiv 1/2 - sin^2 θ_{23}$ $ν_mu$, $\barν_mu$ survival probabilities and binned up-down asymmetries Error analysis and sensitivity to $D$

Tomas Brauner

We construct the chiral perturbation theory for two-color QCD with two quark flavors as an effective theory on the SO(6)/SO(5) coset space. This formulation turns out to be particularly useful for extracting the physical content of the theory when finite baryon and isospin chemical potentials are introduced, and Bose--Einstein condensation sets on.

Romesh K. Kaul

We present a formulation of gravity in terms of a theory based on complex SU(2) gauge fields with a general coordinate invariant action functional quadratic in the field strength. Self-duality or anti-self-duality of the field strength emerges as a constraint from the equations of motion of this theory. This in turn leads to Einstein gravity equations for a

Mohammad Mansouryar

A design of a configuration for violation of the averaged null energy condition (ANEC) and consequently other classic energy conditions (CECs), is presented. The methods of producing effective exotic matter (EM) for a traversable wormhole (TW) are discussed. Also, the approaches of less necessity of TWs to EM are considered. The result is, TW and similar str

Ruben Vandeginste, Bart Demoen

The design and implementation of an incremental copying heap garbage collector for WAM-based Prolog systems is presented. Its heap layout consists of a number of equal-sized blocks. Other changes to the standard WAM allow these blocks to be garbage collected independently. The independent collection of heap blocks forms the basis of an incremental collecting

Yuesong Li, Constantine Yannouleas, Uzi Landman

Using the method of breaking of circular symmetry and of subsequent symmetry restoration via projection techiques, we present calculations for the ground-state energies and excitation spectra of N-electron parabolic quantum dots in strong magnetic fields in the medium-size range 10 <= N <= 30. The physical picture suggested by our calculations is that of fin

Carlo A. Rozzi, Daniele Varsano, Andrea Marini, Eberhard K. U. Gross

We present a new reciprocal space analytical method to cutoff the long range interactions in supercell calculations for systems that are infinite and periodic in 1 or 2 dimensions, extending previous works for finite systems. The proposed cutoffs are functions in Fourier space, that are used as a multiplicative factor to screen the bare Coulomb interaction.

A. Singha, A. Ghosh, N. R. Ray, A. Roy

The correlations between properties of hydrogenated diamond like carbon films and their Raman spectra have been investigated. The films are prepared by plasma deposition technique, keeping different hydrogen to methane ratio during the growth process. The hydrogen concentration, sp$^3$ content, hardness and optical Tauc gap of the materials have been estimat

R. Cortes, A. Tejeda, J. Lobo, C. Didiot

We report an investigation on the properties of 0.33 ML of Sn on Ge(111) at temperatures down to 5 K. Low-energy electron diffraction and scanning tunneling microscopy show that the (3x3) phase formed at 200 K, reverts to a new (root-3xroot-3)R30 phase below 30 K. The vertical distortion characteristic of the (3x3) phase is lost across the phase transition.

Karoly F. Pal

Hysteretic optimization is a heuristic optimization method based on the observation that magnetic samples are driven into a low energy state when demagnetized by an oscillating magnetic field of decreasing amplitude. We show that hysteretic optimization is very good for finding ground states of Sherrington-Kirkpatrick spin glass systems. With this method it

F. Cordero

YBCO, LSCO and Ru-1212 have been extensively studied by measuring the complex dynamic Young&#39;s modulus at 0.5-20 kHz between 1 and 900 K. The elastic energy loss is peaked at the temperatures where the relaxation rate of any microscopic process coupled to strain equals the measuring frequency. The reliability of the anelastic experiments and of the assign

H. Aubin, C. A. Marrache-Kikuchi, A. Pourret, K. Behnia

A study of magnetic-field tuned superconductor-insulator transitions in amorphous $Nb_{0.15}Si_{0.85}$ thin films shows that quantum superconductor-insulator transitions are characterized by an unambiguous signature -- a kink in the temperature profile of the critical magnetic field. Using this criterion, we show that the nature of the magnetic-field tuned s

S. J. Crowe, M. R. Lees, D. McK. Paul, R. I. Bewley

The effect of externally applied pressure on the magnetic behavior of Cu2Te2O5(BrxCl{1-x})2 with x = 0, 0.73 and 1, is investigated by a combination of magnetic susceptibility, neutron diffraction and neutron inelastic scattering measurements. The magnetic transition temperatures of the x = 0 and 0.73 compositions are observed to increase linearly with incre

Emily Gardel, Ellen Keene, Sonia Dragulin, Nalini Easwar

We report measurements in a 2-dimensional, gravity-driven, collisional, granular flow of the normal force delivered to the wall and of particle velocity at several points in the flow. The wall force and the flow velocity are negatively correlated. This correlation falls off only slowly with distance transverse to the flow, but dies away on the scale of a few

Andre Eckardt, Christoph Weiss, Martin Holthaus

We demonstrate that the transition from a superfluid to a Mott insulator in the Bose-Hubbard model can be induced by an oscillating force through an effective renormalization of the tunneling matrix element. The mechanism involves adiabatic following of Floquet states, and can be tested experimentally with Bose-Einstein condensates in periodically driven opt

Sergey Savel&#39;ev, Xuedong Hu, A. Kasumov, Franco Nori

Analyzing recent experimental results, we find similar behaviors and a deep analogy between three-junction superconducting qubits and suspended carbon nanotubes. When these different systems are ac-driven near their resonances, the resonance single-peak, observed at weak driving, splits into two sub-peaks (Fig. 1) when the driving increases. This unusual beh

Andre Eckardt, Tharanga Jinasundera, Christoph Weiss, Martin Holthaus

We study many-body tunneling of a small Bose-Einstein condensate in a periodically modulated, tilted double-well potential. Periodic modulation of the trapping potential leads to an analog of photon-assisted tunneling, with distinct signatures of the interparticle interaction visible in the amount of particles transferred from one well to the other. In parti

Stefan Hollos, Richard Hollos

We show how to use the lattice Green function to calculate capacitances in two dimensions with boundary conditions at infinity. It is shown how to calculate coefficients of capacitance and induction from the lattice Green function. A general analysis of two arbitrary conductors is carried out. It is shown how the calculations can be simplified in the case of

Eran Lebanon, Jerome Rech, P. Coleman, Olivier Parcollet

Using a Luttinger Ward scheme for interacting gauge particles, we present a conserving many body treatment of a family of fully screened infinite U Anderson models that has a smooth cross-over into the Fermi liquid state, with a finite scattering phase shift at zero temperature and a Wilson ratio greater than one. We illustrate our method, computing the temp

De-yong Wang, Hong-ye Wu, Li-jun Chen, Wei He

The growth of well-ordered Mn nanodots arrays on Si(111)-7*7 reconstructed surface was investigated by means of scanning tunneling microscopy (STM) as well as Kinetic Monte Carlo (KMC) simulation. Mn atoms deposited slowly onto elevated substrates were observed to occupy preferentially on the faulted half unit cells (FHUCs) of Si(111)-7*7 surface. The prefer

R. J. Radwanski, Z. Ropka

Magnetic properties of stechiometric YTiO3 has been calculated within the single-ion-based paradigm taking into account the low-symmetry crystal field and the intra-atomic spin-orbit coupling of the Ti3+ ion. Despite of the very simplified approach the calculations reproduce perfectly the value of the magnetic moment and its direction as well as temperature

S. Dusuel, J. Vidal, J. M. Arias, J. Dukelsky

Two-level boson systems displaying a quantum phase transition from a spherical (symmetric) to a deformed (broken) phase are studied. A formalism to diagonalize Hamiltonians with $O(2L+1)$ symmetry for large number of bosons is worked out. Analytical results beyond the simple mean-field treatment are deduced by using the continuous unitary transformations tec

K. Park

A connection between quantum antiferromagnetism and high $T_C$ superconductivity is theoretically investigated by analyzing the t-J model and its relationships to the Gutzwiller-projected BCS Hamiltonian. After numerical corroboration via exact diagonalization, it is analytically shown that the ground state of the t-J model at half filling (i.e., the 2D anti

L. A. Lopez, W. N. Brandt, C. Vignali, D. P. Schneider

We present the results of Chandra ACIS-S snapshot observations of six radio-loud quasars (RLQs) at z=3.5-4.7. These observations sample luminous RLQs with moderate-to-high radio-loudness (R=200-9600) and aim to connect the X-ray properties of radio-quiet quasars (R<10) and highly radio-loud blazars (R>1000) at high redshift. This work extends a study by Bass

T. Yamamoto

The southern site of the Pierre Auger Observatory is under the construction near Malargue in Argentina and now more than 60% of the detectors are completed. The observatory has been collecting data for over 1 year and the cumulative exposure is already similar to that of the largest forerunner experiments. The hybrid technique provides model-independent ener

J. A. Eisner, E. I. Chiang, L. A. Hillenbrand

We present Keck Interferometer observations of TW Hya that spatially resolve its emission at 2 micron wavelength. Analyzing these data together with existing K-band veiling and near-infrared photometric measurements, we conclude that the inner disk consists of optically thin, sub-micron-sized dust extending from ~4 AU to within 0.06 AU of the central star. T

J. A. Eisner, John M. Carpenter

(abridged) We determine the disk mass distribution around 336 stars in the young Orion Nebula cluster by imaging a 2.5&#39; x 2.5&#39; region in 3 mm continuum emission with the Owens Valley Millimeter Array. For this sample of 336 stars, we observe 3 mm emission above the 3-sigma noise level toward ten sources, six of which have also been detected optically

Noam Soker, Gili Bisker

We study the bending of jets in binary stellar systems. A compact companion accretes mass from the slow wind of the mass-losing primary star, forms an accretion disk, and blows two opposite jets. These fast jets are bent by the slow wind. Disregarding the orbital motion, we find the dependence of the bending angle on the properties of the slow wind and the j