July 2006 arXiv papers — page 36

Yitwah Cheung, Pascal Hubert, Howard Masur

In this paper the authors find examples of translation surfaces that have infinitely generated Veech groups, satisfy the topological dichotomy property that for every direction either the flow in that direction is completely periodic or minimal, and yet have minimal but non uniquely ergodic directions.

Hui Hu, Xia-Ji Liu, Peter D. Drummond

We analyse theoretically a single vortex in 3D trapped atomic Fermi gases with population polarization near a broad Feshbach resonance. Above a critical polarization the Andreev-like bound states inside the core become occupied for the majority component. As a result, the local density difference at the core center acquires a sudden rise at low temperautres.

A. Ryd

Recent CLEO-c results on open charm physics at the psi(3770) are presented. Measurements of hadronic and semileptonic branching fractions of the D0 and D+ mesons are discussed as well as the leptonic decay D+ to mu+ nu_mu and determination of the D meson decay constant.

Jian-yu Lu

This paper presents theoretical results indicating that newly discovered nondiffracting beams we call X waves, can propagate in a confined space (wave guide) with specific quantized temporal frequencies. These results could have applications in nondispersive transmission of acoustic, electromagnetic (microwaves) and optical energy through wave guides as well

Chris Savage, Katherine Freese, Paolo Gondolo

In addition to a smooth component of WIMP dark matter in galaxies, there may be streams of material; the effects of WIMP streams on direct detection experiments is examined in this paper. The contribution to the count rate due to the stream cuts off at some characteristic energy. Near this cutoff energy, the stream contribution to the annual modulation of re

Kenji Fukushima

We argue that the gauge invariant source terms in the formalism of the Color Glass Condensate (CGC) should properly describe the target wave-function if the microscopic structure is concerned in the regime where the parton distribution is not quite dense. The quantum property of color charge density is incorporated in the quantum weight function defined with

Jose J. Lunazzi, Noemi I. Rivera

Pseudoscopic (inverted depth) images that keep a continuous parallax were shown to be possible by use of a double diffraction process intermediated by a slit. One diffraction grating directing light to the slit acts as a wavelength encoder of views, while a second diffraction grating decodes the projected image. The process results in the enlargement of the

K. Vant, J. Chiaverini, W. Lybarger, D. J. Berkeland

We report a demonstration of simple and effective loading of strontium ions into a linear radio frequency Paul trap using photoionization. The ionization pathway is 5s2 1S0 -- 5s5p 1P1 -- 5p2 1D2, and the 5p2 1D2 final state is auto-ionizing. Both transitions are driven using diode lasers: a grating-stabilized 922 nm diode doubled in a single pass through po

G. Zambra, M. G. A. Paris

The output of a photodetector consists of a current pulse whose charge has the statistical distribution of the actual photon numbers convolved with a Bernoulli distribution. Photodetectors are characterized by a nonunit quantum efficiency, i.e. not all the photons lead to a charge, and by a finite resolution, i.e. a different number of detected photons leads

F. Benatti, R. Floreanini

Two, non-interacting systems immersed in a common bath and evolving with a Markovian, completely positive dynamics can become initially entangled via a purely noisy mechanism. Remarkably, for certain, phenomenologically relevant environments, the quantum correlations can persist even in the asymptotic long-time regime.

Kei Tokita

Statistical mechanics of relative species abundance (RSA) patterns in biological networks is presented. The theory is based on multispecies replicator dynamics equivalent to the Lotka-Volterra equation, with diverse interspecies interactions. Various RSA patterns observed in nature are derived from a single parameter related to productivity or maturity of a

A. G. Khachatryan, M. J. H. Luttikhof, F. A. van Goor, K. -J. Boller

For the purpose of laser wakefield acceleration, it turned out that also the injection of electron bunches longer than a plasma wavelength can generate accelerated femtosecond bunches with relatively low energy spread. This is of high interest because such injecting bunches can be provided, e.g., by state-of-the-art photo cathode RF guns. Here we point out t

Sitabhra Sinha, Srinivas Raghavendra

Financial markets are subject to long periods of polarized behavior, such as bull-market or bear-market phases, in which the vast majority of market participants seem to almost exclusively choose one action (between buying or selling) over the other. From the point of view of conventional economic theory, such events are thought to reflect the arrival of ``e

Krzysztof Pachucki

Corrections of order $α^4$Ry are calculated for the singlet states $1^1S_0$ and $2^1S_0$ of the helium atom. The result for $1^1S_0$ state is in slight disagreement with that of Korobov and Yelkhovsky in [Phys. Rev. Lett. {\bf 87}, 193003 (2001)]. The results obtained lead to a significant improvement of transition frequencies between low lying levels of the

Samuel Andriamonje, Gregory Andriamonje, Stephan Aune, Gilles Ban

A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. T

F. Biraben, M. Cadoret, P. Clad, G. Genevs

We propose two experimental schemes to determine and so to realize the Avogadro constant $N\_{A}$ at the level of 10$^{-7}$ or better with a watt balance experiment and a cold atom experiment measuring $h/m(X)$ (where $h$ is the Planck constant and $m(X)$ the mass of the atom $X$). We give some prospects about achievable uncertainties and we discuss the oppo

Stefano Tonzani, Chris H. Greene

In the context of damage to DNA by low-energy electrons, we carry out calculations of electron scattering from tetrahydrofuran and phosphoric acid, models of the subunits in the DNA backbone, as a first step in simulating the electron capture process that occurs in the cell. In the case of tetrahydrofuran, we also compare with previous theoretical and experi

Stefano Tonzani

FERM3D is a three-dimensional finite element program, for the elastic scattering of a low energy electron from a general polyatomic molecule, which is converted to a potential scattering problem. The code is based on tricubic polynomials in spherical coordinates. The electron-molecule interaction is treated as a sum of three terms: electrostatic, exchange. a

J. S. Guzman, A. Wojciechowski, J. E. Stalnaker, K. Tsigutkin

Nonlinear magneto-optical Faraday rotation (NMOR) on the potassium D1 and D2 lines was used to study Zeeman relaxation rates in an antirelaxation paraffin-coated 3-cm diameter potassium vapor cell. Intrinsic Zeeman relaxation rates of $γ^{NMOR}/2π=2.0(6) {\rm Hz}$ were observed. The relatively small hyperfine intervals in potassium lead to significant differ

Peter Constantin, Boris Levant, Edriss S. Titi

In this paper we continue the analytical study of the sabra shell model of energy turbulent cascade initiated in \cite{CLT05}. We prove the global existence of weak solutions of the inviscid sabra shell model, and show that these solutions are unique for some short interval of time. In addition, we prove that the solutions conserve the energy, provided that

Jose J. Lunazzi, Noemi I. Rivera

Pseudoscopic images that keep the continuous parallax are shown to be possible due to a double diffraction process intermediated by a slit. One diffraction grating acts as a wavelength encoder of views while a second diffraction grating decodes the projected image. The process results in the enlargement of the image under common white light illumination.

Glauber T. Silva, Shigao Chen, Leonardo P. Viana

We report on parametric amplification in dynamic radiation force produced by a bichromatic acoustic beam in a fluid. To explain this effect we develop a theory taking into account the nonlinearity of the fluid. The theory is validated through an experiment to measure the dynamic radiation force on an acrylic sphere. Results exhibit an amplification of 66 dB

J. Kriz, P. Seba

We show that the recoils of the body caused by cardiac motion and blood circulation provide a noninvasive method capable to display the motions of the heart muscle and the propagation of the pulse wave along aorta and its branches. The results are compared with the data obtained invasively during a heart catheterization. We show that the described noninvasiv

Nir Barnea, Winfried Leidemann, Giuseppina Orlandini

The J-matrix inverse scattering nucleon-nucleon potentials (JISP), describing both two-nucleon data and bound and resonant states of light nuclei to high accuracy, are tested on the total photoabsorption cross sections of Deuteron, Triton, 3He and 4He. The calculations in the three- and four-body systems are carried out via the Lorentz integral transform met

S. Karataglidis, K. Amos

Results are presented for the elastic scattering of electrons and protons from the exotic He and Li isotopes. Comparison with scattering results from the stable He and Li nuclei allows for an investigation into the effects that the extensive neutron distributions have on the charge density. For comparison we also consider the proton halo nucleus 8B. The cons

Z. Sosin

Experimental correlation between the rms nucleus charge radius and the neutron-proton asymmetry is discussed. Simple attempt of explanation of this correlation using a semi-empirical liquid drop model which takes into account nuclear compressibility, nuclear deformation and neutron skin effects is presented. It seems that such procedure could be used as a to

V. M. Bystritsky, V. V. Gerasimov, J. Wozniak

The measurement method and results measuring of the stopping power ratio of helium-3 and deuterium atoms for muons slowed down in the D/$^3$He mixture are presented. Measurements were performed at four values of pure $^3$He gas target densities, $ϕ_{He} = 0.0337, 0.0355, 0.0359, 0.0363$ (normalized to the liquid hydrogen density) and at a density 0.0585 of t

Fpi2 collaboration, T. Horn, K. Aniol, J. Arrington

The H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F_pi) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F_pi is a free par

The NA57 Collaboration

The transverse mass spectra of K0s, Lambda, Xi and Omega particles produced in Pb-Pb collisions at 40 A GeV/c have been studied for a sample of events corresponding to the most central 53% of the inelastic Pb-Pb cross-section. We analyze the distributions in the framework of a parameterized model inspired by hydrodynamics. The dependence of the freeze-out pa

Lubomir M. Kovachev

The applied method of the amplitude envelopes give us the possibility to describe a new class of amplitude equations governing the propagation of optical pulses in media with dispersion, dispersionless media and vacuum. We normalized these amplitude equations and obtained five dimensionless parameters that determine different linear and nonlinear regimes of

Jens Bolte, Hans-Michael Stiepan

We examine spectra of Dirac operators on compact hyperbolic surfaces. Particular attention is devoted to symmetry considerations, leading to non-trivial multiplicities of eigenvalues. The relation to spectra of Maass-Laplace operators is also exploited. Our main result is a Selberg trace formula for Dirac operators on hyperbolic surfaces.

M. Huber, E. Stockmeyer

Recently the block-diagonalization of Dirac-operators was investigated from a mathematical point of view in the one-particle case. We extend this result to the $N$-particle case. This leads to a perturbative realization of the Furry picture in the $N$-particle two-spinor space.

G. Berkolaiko, J. P. Keating, U. Smilansky

We prove quantum ergodicity for a family of graphs that are obtained from ergodic one-dimensional maps of an interval using a procedure introduced by Pakonski et al (J. Phys. A, v. 34, 9303-9317 (2001)). As observables we take the L^2 functions on the interval. The proof is based on the periodic orbit expansion of a majorant of the quantum variance. Specific

Ernie Croot

Fix a density d in (0,1], and let F_p^n be a finite field, where we think of p fixed and n tending to infinity. Let S be any subset of F_p^n having the minimal number of three-term progressions, subject to the constraint |S| is at least dp^n. We show that S must have some structure, and that up to o(p^n) elements, it is a union of a small number of cosets of

Marc Dambrine, Djalil Kateb

We consider the inverse conductivity problem with one measurement for the equation $div((σ\_1+(σ\_2-σ\_1)χ\_D)\nabla{u})=0$ determining the unknown inclusion $D$ included in $Ω$. We suppose that $Ω$ is the unit disk of $\mathbb{R}^2$. With the tools of the conformal mappings, of elementary Fourier analysis and also the action of some quasi-conformal mapping

Alexei Panchishkin

For a prime number $p\ge 5$, we consider three classical cusp eigenforms $f_j(z)$ of weights $k_1, k_2, k_3$, of conductors $N_1, N_2, N_3$, and of nebentypus characters $ψ_j \bmod N_j$. According to H.Hida and R.Coleman, one can include each $f_j$ into a {$p$-adic analytic family} $k_j \mapsto \{f_{j,k_j}\}$ of cusp eigenforms $f_{j,k_j}$ of weights $k_j$ i

Olena V. Mul, Delfim F. M. Torres

We report on the possibilities of using the method of normal fundamental systems for solving some problems of oscillation theory. Large elastic dynamical systems with continuous and discrete parameters are considered, which have many different engineering applications. Intensive oscillations in such systems are possible, but not desirable. Therefore, it is v

Natalia Castellana, Juan A. Crespo, Jerome Scherer

Relying on the computation of the Andre-Quillen homology groups for unstable Hopf algebras, we prove that the mod p cohomology of the n-connected cover of a finite H-space is always finitely generated as algebra over the Steenrod algebra.

Olena V. Mul, Delfim F. M. Torres, Volodymyr P. Kravchenko

Dynamics of the hybrid systems of aerial cable-ways is investigated. The eigenvalue problems are considered for such hybrid systems with different assumptions. An overview of different methods for eigenvalue problems is given. In the research, the method of the normal fundamental systems is applied, which turns out to be very effective for the considered pro

Gábor Elek

Introducing and studying the pattern frequency algebra, we prove the analogue of Lück's approximation theorems on $L^2$-spectral invariants in the case of aperiodic order. These results imply a uniform convergence theorem for the integrated density of states as well as the positivity of the logarithmic determinant of certain discrete Schrodinger operator

Cristiana J. Silva, Delfim F. M. Torres

Newton's problem of minimal resistance is one of the first problems of optimal control: it was proposed, and its solution given, by Isaac Newton in his masterful Principia Mathematica, in 1686. The problem consists of determining, in dimension three, the shape of an axis-symmetric body, with assigned radius and height, which offers minimum resistance whe

Christian Haase, Andreas Paffenholz

The toric ideals of $3\times 3$ transportation polytopes $T$ are quadratically generated. The only exception is the Birkhoff polytope $B_3$. If $T$ is not a multiple of $B_3$, these ideals even have squarefree quadratic initial ideals. This class contains all smooth $3 \times 3$ transportation polytopes.

Erwin Bolthausen, Ofer Zeitouni

We present a multiscale analysis for the exit measures from large balls in Z^d, d\geq 3, of random walks in certain i.i.d. random environments which are small perturbations of the fixed environment corresponding to simple random walk. Our main assumption is an isotropy assumption on the law of the environment, introduced by Bricmont and Kupianien. The analys

Karl Schlechta

We examine problems due to lack of domain closure and definability preservation

P. Zinn-Justin

We prove the Razumov--Stroganov conjecture relating ground state of the O(1) loop model and counting of Fully Packed Loops in the case of certain types of link patterns. The main focus is on link patterns with three series of nested arches, for which we use as key ingredient of the proof a generalization of the Mac Mahon formula for the number of plane parti

Urs Hartl

In this survey we explain the main ingredients and results of the analogue of Fontaine-Theory in equal positive characteristic which was recently developed by Genestier-Lafforgue and the author.

Taekyun Kim

We will study p-adic invariant integerals involving trigonometric functions

Mike Boyle, Bryant Lee

We develop a rather elaborate computer program to investigate the jointly periodic points of one-dimensional cellular automata. The experimental results and mathematical context lead to questions, conjectures and a contextual theorem.

Alex Eskin, David Fisher, Kevin Whyte

In this note, we announce the first results on quasi-isometric rigidity of non-nilpotent polycyclic groups. In particular, we prove that any group quasi-isometric to the three dimenionsional solvable Lie group Sol is virtually a lattice in Sol. We prove analogous results for groups quasi-isometric to $R \ltimes R^n$ where the semidirect product is defined by

Martin Klazar, Florian Luca

Let m(n) be the number of ordered factorizations of n in factors larger than 1. We prove that for every eps>0 n^{rho} m(n) < exp[(log n)^{1/rho}/(loglog n)^{1+eps}] holds for all integers n>n_0, while, for a constant c>0, n^{rho} m(n) > exp[c(log n)^{1/ρ}/(loglog n)^{1/rho}] holds for infinitely many positive integers n, where rho=1.72864... is the real solu

Ernie Croot

Given a density t in (0,1], and a prime p, let S be any subset of F_p having at least tp elements, and having the least number of three-term arithmetic progressions mod p among all subsets of F_p with at least tp elements. Define N(t,p) to be 1/p^2 times the number of three-term arithmetic progressions in S modulo p. Note that N(t,p) does not depend on S --

Chunhui Lai

A sequence $S$ is potentially $K_{m}-P_{k}$ graphical if it has a realization containing a $K_{m}-P_{k}$ as a subgraph. Let $σ(K_{m}-P_{k}, n)$ denote the smallest degree sum such that every $n$-term graphical sequence $S$ with $σ(S)\geq σ(K_{m}-P_{k}, n)$ is potentially $K_{m}-P_{k}$ graphical. In this paper, we prove that $σ(K_{m}-P_{k}, n)\geq (2m-6)n-(m-

Chunhui Lai

A sequence $S$ is potentially $K_{p,1,1}$ graphical if it has a realization containing a $K_{p,1,1}$ as a subgraph, where $K_{p,1,1}$ is a complete 3-partite graph with partition sizes $p,1,1$. Let $σ(K_{p,1,1}, n)$ denote the smallest degree sum such that every $n$-term graphical sequence $S$ with $σ(S)\geq σ(K_{p,1,1}, n)$ is potentially $K_{p,1,1}$ graphi

Takuro Mochizuki

Let $X$ be a smooth polarized algebraic surface over the compex number field. We discuss the invariants obtained from the moduli stacks of semistable sheaves of arbitrary ranks on $X$. For that purpose, we construct the virtual fundamental classes of some moduli stacks, and we show the transition formula of the integrals over the moduli stacks of the $δ$-sta

David Kastor, Jennie Traschen

We consider how variations in the moduli of the compactification manifold contribute pdV type work terms to the first law for Kaluza-Klein black holes. We give a new proof for the circle case, based on Hamiltonian methods, which demonstrates that the result holds for arbitrary perturbations around a static black hole background. We further apply these method

Larus Thorlacius

A simple argument is given that a traversable Cauchy horizon inside a black hole is incompatible with unitary black hole evolution. The argument assumes the validity of black hole complementarity and applies to a generic black hole carrying angular momentum and/or charge. In the second part of the paper we review recent work on the semiclassical geometry of

Dan Hooper, Andrew M. Taylor

In this article, we explore the ability of direct and indirect dark matter experiments to not only detect neutralino dark matter, but to constrain and measure the parameters of supersymmetry. In particular, we explore the relationship between the phenomenological quantities relevant to dark matter experiments, such as the neutralino annihilation and elastic

Howard Baer, Eun-Kyung Park, Xerxes Tata, Ting T. Wang

String compactification with fluxes yields MSSM soft SUSY breaking terms that receive comparable contributions from modulus and anomaly mediation whose relative strength is governed by a phenomenological parameter $α$. Gaugino and first/second generation (and sometimes also Higgs and third generation) scalar mass parameters unify at a mirage unification scal

Alan Kostelecky, Matthew Mewes

We show that the recent measurements of linear polarization in gamma rays from GRB 930131 and GRB 960924 constrain certain types of relativity violations in photons to less than parts in 10^{37}, representing an improvement in sensitivity by a factor of 100,000.

Jaroslaw A. Nowak

A neutrino event generator developed by the Wroclaw Neutrino Group is described. The physical models included in the generator are discussed and illustrated with the results of simulations. The considered processes are quasi-elastic scattering and pion production modelled by combining the $Δ$ resonance excitation and deep inelastic scattering.

Eung Jin Chun, Hang Bae Kim

Motivated by the recent observation of the 511 keV $γ$-ray line emissions from the galactic bulge and an explanation for it by the decays of light dark matter particles, we consider the light axino whose mass can be in the 1-10 MeV range, particularly, in the context of gauge-mediated supersymmetry breaking models. We discuss the production processes and cos

Yu. A. Simonov, M. A. Trusov

Using the expansion of the baryon wave function in a series of products of single quark bispinors (Dirac orbitals), the nonsinglet axial and tensor charges of a nucleon are calculated. The leading term yields $g_A = 1.27$ in good agreement with experiment. Calculation is essentially parameter-free and depends only on the strong coupling constant value $α_s$.

Andreas S. Kronfeld

In recent years, we used lattice QCD to calculate some quantities that were unknown or poorly known. They are the $q^2$ dependence of the form factor in semileptonic $D\to Klν$ decay, the leptonic decay constants of the $D^+$ and $D_s$ mesons, and the mass of the $B_c$ meson. In this paper, we summarize these calculations, with emphasis on their (subsequent)

Tristan Faber

The crucial role played by pressure in general relativity is explored in the mathematically simple context of a static spherically symmetric geometry. By keeping all pressure terms, the standard formalisms of rotation curve and gravitational lensing observations are extended to a first post-Newtonian order. It turns out that both post-Newtonian formalisms en

F. Ya. Khalili

The intracavity topologies of laser gravitational-wave detectors are the promising way to obtain sensitivity of these devices significantly better than the Standard Quantum Limit (SQL). The most challenging element of the intracavity topologies is the \emph{local meter} which has to monitor position of a small ($1\div10$ gram) local mirror and which precisio

S. Rouhani, M. V. Takook

It was shown that quantum metric fluctuations smear out the singularities of Green&#39;s functions on the light cone [1], but it does not remove other ultraviolet divergences of quantum field theory. We have proved that the quantum field theory in Krein space, {\it i.e.} indefinite metric quantization, removes all divergences of quantum field theory with exc

Nikodem J. Poplawski

We study the present, flat isotropic universe in 1/R-modified gravity. We use the Palatini (metric-affine) variational principle and the Einstein (metric-compatible connected) conformal frame. We show that the energy density scaling deviates from the usual scaling for nonrelativistic matter, and the largest deviation occurs in the present epoch. We find that

Lorenzo Iorio

We discuss the impact of the present-day uncertainties in the recently released CHAMP and/or GRACE Earth gravity models on the measurement of the Lense-Thirring effect with the nodes of the LAGEOS satellites. Also the role of the secular variations Jdots of the even zonal harmonics is quantitatively assessed via numerical simulations and tests. While the sys

Christian Lavault, Jean-François Marckert, Vlady Ravelomanana

Radio networks (RN) are distributed systems (\textit{ad hoc networks}) consisting in $n \ge 2$ radio stations. Assuming the number $n$ unknown, two distinct models of RN without collision detection (\textit{no-CD}) are addressed: the model with \textit{weak no-CD} RN and the one with \textit{strong no-CD} RN. We design and analyze two distributed leader elec

James Aspnes, Yang Richard Yang, Yitong Yin

We consider algorithms for load balancing on unreliable machines. The objective is to optimize the two criteria of minimizing the makespan and minimizing job reassignments in response to machine failures. We assume that the set of jobs is known in advance but that the pattern of machine failures is unpredictable. Motivated by the requirements of BGP routing,

Oskar Sandberg, Ian Clarke

Small-world networks, which combine randomized and structured elements, are seen as prevalent in nature. Several random graph models have been given for small-world networks, with one of the most fruitful, introduced by Jon Kleinberg, showing in which type of graphs it is possible to route, or navigate, between vertices with very little knowledge of the grap

Jos H. Weber, Khaled A. S. Abdel-Ghaffar

The performance of iterative decoding techniques for linear block codes correcting erasures depends very much on the sizes of the stopping sets associated with the underlying Tanner graph, or, equivalently, the parity-check matrix representing the code. In this paper, we introduce the notion of dead-end sets to explicitly demonstrate this dependency. The cho

J. Diaz, D. Mitsche, X. Perez

We show for an arbitrary $\ell_p$ norm that the property that a random geometric graph $\mathcal G(n,r)$ contains a Hamiltonian cycle exhibits a sharp threshold at $r=r(n)=\sqrt{\frac{\log n}{α_p n}}$, where $α_p$ is the area of the unit disk in the $\ell_p$ norm. The proof is constructive and yields a linear time algorithm for finding a Hamiltonian cycle of

G. A. Maney

This is a rough draft synopsis of a book presently in preparation. This book provides a systematic critique of the software industry. This critique is accomplished using classical methods in practical design science.

G. Lopez, P. Lopez, X. E. Lopez

We use the phase space position-velocity ($x,v$) to deal with the statistical properties of velocity dependent dynamical systems, like dissipative ones. Within this approach, we study the statistical properties of an ensemble of harmonic oscillators in a linear weak dissipative media. Using the Debye model of a crystal, we calculate at first order in the dis

E. B. Herbold, V. F. Nesterenko

The shock wave structure in a one-dimensional lattice (e.g. granular chain) with a power law dependence of force on displacement between particles with viscous dissipation is considered and compared to the corresponding long wave approximation. A dissipative term depending on the relative velocity between neighboring particles is included in the discrete mod

Doron L. Bergman, Ryuichi Shindou, Gregory A. Fiete, Leon Balents

We study the effect of quantum fluctuations on the half-polarized magnetization plateau of a pyrochlore antiferromagnet. We argue that an expansion around the easy axis limit is appropriate for discussing the ground state selection amongst the classically degenerate manifold of collinear states with a 3:1 ratio of spins parallel/anti-parallel to the magnetiz

Alexander Weisse, Georg Hager, Alan R. Bishop, Holger Fehske

We explore the ground-state phase diagram of a Heisenberg spin chain coupled locally to optical phonons (bond coupling), using large-scale density matrix renormalization group calculations and an extended perturbative analysis. For the quantum phase transition from the spin liquid to the dimerized phase, we find deviations from previous quantum Monte Carlo a

X. C. Zhang, I. Martin, H. W. Jiang

In a two-subband GaAs/AlGaAs two-dimensional electron system, the phase diagram of longitudinal resistivity ρ_xx in density and magnetic field plane exhibits an intriguing structure centered at filling factor ν= 4 which is strikingly different from the ring-like structures at lower magnetic fields. Thermal activation measurements reveal an anticrossing gap o

P. Sankowski, P. Kacman, J. A. Majewski, T. Dietl

A model of coherent tunneling, which combines multi-orbital tight-binding approximation with Landauer-Büttiker formalism, is developed and applied to all-semiconductor heterostructures containing (Ga,Mn)As ferromagnetic layers. A comparison of theoretical predictions and experimental results on spin-dependent Zener tunneling, tunneling magnetoresistance (TMR

Chia-Hui Lin, Hsiu-Hau Lin, Tzay-Ming Hong

We revisit the non-collinear exchange coupling across the trilayer magnetic junction mediated by the diluted-magnetic-semiconductor thin film. By numerical approaches, we investigate the spiral angle between the ferromagnetic layers extensively in the parameter space. In contrast to previous study, we discovered the important role of spin relaxation, which t

Wen-Min Huang, Cheng-Hung Chang, Hsiu-Hau Lin

We investigate the non-collinear exchange coupling across the trilayer magnetic junction composed of an intermediate layer with Rashba interaction and two sandwiching ferromagnetic ones. To compute the mediated exchange coupling, one needs to go beyond the single-particle argument and integrate over the contributions from the whole Fermi surface. Surprisingl

Shih-Jye Sun, Hsiu-Hau Lin

Employing the self-consistent Green&#39;s function approach, we studied the temperature dependence of the spin-wave stiffness in diluted magnetic semiconductors. Note that the Green&#39;s function approach includes the spatial and temperature fluctuations simultaneously which was not possible within conventional Weiss mean-field theory. It is rather interest

I. L. Aleiner, K. B. Efetov

Quenched disorder in graphene is characterized by 5 constants and experiences the logarithmic renormalization even from the spatial scales smaller than the Fermi wavelength. We derive and solve renormalization group equations (RGEs) describing the system at such scales. At larger scales, we derive a non-linear supermatrix $σ$-model completely describing loca

Yu-Jen Wang, Chih-Huang Lai, Po-Hsiang Huang, Hsiu-Hau Lin

We studied the interlayer coupling in the quadrilayer consisting of IrMn/CoFe (bottom layer)/NiFeOx/ CoFe (top layer). The in-plane perpendicular interlayer coupling is observed between CoFe layers at room temperature. An anisotropy transition from uniaxial to unidirectional in the perpendicular direction is observed around Tt = 55 K. The nano-oxide layer Ni

K. S. Troche, V. R. Coluci, R. Rurali, D. S. Galvão

In this work we investigated the encapsulation of C$_20$ and C$_30$ fullerenes into semiconducting carbon nanotubes to study the possibility of bandgap engineering in such systems. Classical molecular dynamics simulations coupled to tight-binding calculations were used to determine the conformational and electronic properties of carbon nanotube supercells co

Ippei Danshita, Shunji Tsuchiya

We study the elementary excitations of Bose-Einstein condensates in a one-dimensional periodic potential and discuss the stability of superfluid flow based on the Kronig-Penney model. We analytically solve the Bogoliubov equations and calculate the excitation spectrum. The Landau and dynamical instabilities occur in the first condensate band when the superfl

A. Jagannathan, R. Moessner, S. Wessel

We study quantum antiferromagnets on two-dimensional bipartite lattices. We focus on local variations in the properties of the ordered phase which arise due to the presence of inequivalent sites or bonds in the lattice structure, using linear spin wave theory and quantum Monte Carlo methods. Our primary finding is that sites with a high coordination tend to

Ina Yeo, Kyung-Soo Yi

We first exploit the spin symmetry relation $f^{\rm xc}_{s\bar s} (ζ)=f^{\rm xc}_{\bar s s}(-ζ)$ for the exact exchange correlation kernel $f^{\rm xc}_{s\bar s}(ζ)$ in an inhomogeneous many electron system with arbitrary spin polarization $ζ$. The physical condition required to satisfy the specific symmetry relation $f^{\rm xc}_{s\bar s}(ζ) = f^{\rm xc}_{\ba

A. S. Parvan, T. S. Biro

Previous results on Renyi and Wang&#39;s formalism of the Tsallis thermostatics are founded by using an extensive variable z connected to the entropic parameter q. It is shown that in the thermodynamical limit both the Tsallis and Renyi entropies are extensive functions of state and the temperature of the system is intensive. In this limit Wang&#39;s incompl

Martin Hasenbusch

We simulate the improved three-dimensional two-component phi^4 model on the simple cubic lattice in the low and the high temperature phase for reduced temperatures down to |T-T_c|/T_c \approx 0.0017 on lattices of a size up to 350^3. Our new results for the internal energy and the specific heat are combined with the accurate estimates of beta_c and data for

Jakub Jedrak, Jozef Spalek, Gertrud Zwicknagl

We determine the localization threshold in a partially filled and orbitally degenerate model of correlated electrons. Particular emphasis is put on a non-integer band filling, when the system decomposes into the localized and the itinerant subsystems; this situation is described by an effective s-d model. A simultaneous transition to the ferromagnetic state

Roberto Mulet, Daniel Stariolo

The Langevin dynamics of a system exhibiting a Fluctuation Induced First Order Phase Transition is solved within the self consistent Hartree Approximation. Competition between interactions at short and long length scales gives rise to spatial modulations in the order parameter, like stripes in 2d and lamellae in 3d. We show that when the time scale of observ

Keiji Murata, Hiroki Saito, Masahito Ueda

A spin-1 ferromagnetic Bose-Einstein condensate subject to a certain magnetic field exhibits a broken-axisymmetry phase in which the magnetization tilts against the applied magnetic field due to the competition between ferromagnetism and linear and quadratic Zeeman effects. The Bogoliubov analysis shows that in this phase two Goldstone modes associated with

Z. F. Hou

Using projector augmented wave approach within the generalized gradient approximation, we have studied the structural property and electronic structure of ZrB12. The calculated lattice constants and bulk modulus are in good agreement with the available experimental values. A detailed study of the electronic structure and the charge-density redistribution rev

Jean-Francois Berret, Kazuhiko Yokota, Mikel Morvan, Ralf Schweins

We report on the formation and the structural properties of supermicellar aggregates also called electrostatic complexes, made from mineral nanoparticles and polyelectrolyte-neutral block copolymers in aqueous solutions. The mineral particles put under scrutiny are ultra-fine and positively charged yttrium hydroxyacetate nanoparticles. Combining light, neutr

Chisa Hotta, Nobuo Furukawa

We study the recently reported characteristic gapless charge ordered state in a spinless fermion system on a triangular lattice under strong inter-site Coulomb interactions. In this state the charges are spontaneously divided into solid and liquid component, and the former solid part aligns in a Wigner crystal manner while the latter moves among them like a

Oleg G. Shpyrko, Reinhard Streitel, V. S. K. Balagurusamy, Alexei Y. Grigoriev

X-ray measurements reveal a crystalline monolayer at the surface of the eutectic liquid Au_{82}Si_{18}, at temperatures above the alloy&#39;s melting point. Surface-induced atomic layering, the hallmark of liquid metals, is also found below the crystalline monolayer. The layering depth, however, is threefold greater than that of all liquid metals studied to

F. V. Kyrychenko, C. A. Ullrich

In III-V dilute magnetic semiconductors (DMSs) such as Ga$_{1-x}$Mn$_x$As, the impurity positions tend to be correlated, which can drastically affect the electronic transport properties of these materials. Within the memory function formalism we have derived a general expression for the current relaxation kernel in spin and charge disordered media and have c

Junya Matsunami, Mitsuaki Ooya, Tohru Okamoto

The resistivity change due to electron spin resonance (ESR) absorption is investigated in a high-mobility two-dimensional electron system formed in a Si/SiGe heterostructure. Results for a specific Landau level configuration demonstrate that the primary cause of the ESR signal is a reduction of the spin polarization, not the effect of electron heating. The l