March 2002 arXiv papers — page 24

G. V. Dass, W. Grimus

We focus on two aspects of CPT invariance in neutral-meson--antimeson ($M^0 \bar M^0$) mixing: 1. Tests of CPT invariance, using only the property of ``lack of vacuum regeneration'', which occurs as a part of the well-known Lee--Oehme--Yang (LOY) theory; 2. Methods for extracting the CPT-violating mixing parameter $θ$ through explicit calculations by

G. J. Ferland, A. C. Fabian, R. M. Johnstone

This is a progress report on our numerical simulations of conditions in the cold cores of cooling flow condensations. The physical conditions in any non-equilibrium plasma are the result of a host of microphysical processes, many involving reactions that are research areas in themselves. We review the dominant physical processes in our previously published s

N. N. Achasov, A. V. Kiselev

We show that a recent proposal by Close and Kirk fails to describe a_0(980) and f_0(980) mixing when physical masses and widths are included.

S. Rai Choudhury, Naveen Gaur, Namit Mahajan

In this paper we study the polarization asymmetries of the final state lepton in the radiative dileptonic decay of B meson (\bsllg) in the framework of Minimal Supersymmetric Standard Model (MSSM) and various other unified models within the framework of MSSM e.g. mSUGRA, SUGRA (where condition of universality of scalar masses is relaxed) etc. Lepton polariza

R. Schmidt, J. Schulenburg, J. Richter, D. D. Betts

Using exact diagonalization (ED) and linear spin wave theory (LSWT) we study the influence of frustration and quantum fluctuations on the magnetic ordering in the ground state of the spin-1/2 J1-J2 Heisenberg antiferromagnet (J1-J2 model) on the body-centered cubic (bcc) lattice. Contrary to the J1-J2 model on the square lattice, we find for the bcc lattice

Hua Yang, Qing Wang, Yu-Ping Kuang, Qin Lu

We calculate the coefficients in the chiral Lagrangian approximately from QCD based on a previous study of deriving the chiral Lagrangian from the first principles of QCD in which the chiral Lagrangian coefficients are defined in terms of certain Green's functions in QCD. We first show that, in the large N(c)-limit, the anomaly part contributions to the

Lothar Schäfer, Ute Ebert, Artur Baumgärtner

We calculate the coherent dynamical scattering function S_c(q,t;N) of a flexible chain of length N, diffusing through an ordered background of topological obstacles. As an instructive generalization, we also calculate the scattering function S_c(q,t;M,N) for the central piece of length M < N of the chain. Using the full reptation model, we treat global creep

Guray Erkol, Gursevil Turan

We study the differential branching ratio, branching ratio and the forward-backward asymmetry for the exclusive $B_s->ϕ\ell^+ \ell^-$ decay in the two Higgs doublet model. We analyze the dependencies of these quantities on the model parameters and show that these observables are highly sensitive to new physics and hence may provide powerful probe of the SM a

R. Czopnik, P. Garbaczewski

We analyze limitations upon any kinetic theory inspired derivation of a probabilistic counterpart of the Schrödinger picture quantum dynamics. Neither dissipative nor non-dissipative stochastic phase-space processes based on the white-noise (Brownian motion) kinetics are valid candidates unless additional constraints (a suitable form of the energy conservati

Xiao-Gang He, G. Valencia

It has been pointed out recently by Chanowitz that the $Z \to b\bar{b}$ decay asymmetry poses a problem for the standard model whether it is genuine or not [Chanowitz:2001bv]. If this conflict is interpreted as new physics in the b-quark couplings, it suggests a rather large right handed coupling of the b-quark to the Z-boson. We show that it is possible to

Naoki Sasakura

We perform some analytic continuations of the de Sitter thick domain wall solutions obtained in our previous paper hep-th/0201130 in the system of gravity and a scalar field with an axion-like potential. The obtained new solutions represent anti-de Sitter thick domain walls and cosmology. The anti-de Sitter domain wall solutions are periodic, and correspondi

C. Schori, B. Julsgaard, J. L. Soerensen, E. S. Polzik

We report an experiment on mapping a quantum state of light onto the ground state spin of an ensemble of Cs atoms with the life time of 2 milliseconds. Quantum memory for one of the two quadrature phase operators of light is demonstrated with vacuum and squeezed states of light. The sensitivity of the mapping procedure at the level of approximately one photo

L. A. Caron, H. Kröger, X. Q. Luo, G. Melkonyan

We use the quantum action to study the dynamics of quantum system at finite temperature. We construct the quantum action non-perturbatively and find temperature dependent action parameters. Here we apply the quantum action to study quantum chaos. We present a numerical study of a classically chaotic 2-D Hamiltonian system - harmonic oscillators with anharmon

T. Melde, L. Canton, J. P Svenne

We formulate the three-body problem in one dimension in terms of the (Faddeev-type) integral equation approach. As an application, we develop a spinless, one-dimensional (1-D) model that mimics three-nucleon dynamics in one dimension. Using simple two-body potentials that reproduce the deuteron binding, we obtain that the three-body system binds at about 7.5

Jon Eakins, George Jaroszkiewicz

On the basis that the universe is a closed quantum system with no external observers, we propose a paradigm in which the universe jumps through a series of stages. Each stage is defined by a quantum state, an information content, and rules governing temporal evolution. Only some of these rules are currently understood; we can calculate answers to quantum que

I. B. Ivanov

It is shown that evolution of wave functions in nonintegrable quantum systems is unpredictable for a long time T because of rapid growth of number of elementary computational operations $\mathcal O(T)\sim T^α$. On the other hand, the evolution of wave functions in integrable systems can be predicted by the fast algorithms $\mathcal O(T)\sim (log_2 T)^β$ for

J. Bub

It is generally accepted, following Landauer and Bennett, that the process of measurement involves no minimum entropy cost, but the erasure of information in resetting the memory register of a computer to zero requires dissipating heat into the environment. This thesis has been challenged recently in a two-part article by Earman and Norton. I review some rel

A. Acin, G. Vidal, J. I. Cirac

We show that Einstein--Podolsky--Rosen--Bohm (EPR) and Greenberger--Horne--Zeilinger--Mermin (GHZ) states can not generate, through local manipulation and in the asymptotic limit, all forms of three--partite pure--state entanglement in a reversible way. The techniques that we use suggest that there may be a connection between this result and the irreversibil

Patrick Huang, Alexandra Viel, K. Birgitta Whaley

We describe and systematically analyze new implementations of the Projection Operator Imaginary Time Spectral Evolution (POITSE) method for the Monte Carlo evaluation of excited state energies. The POITSE method involves the computation of a correlation function in imaginary time. Decay of this function contains information about excitation energies, which c

V. N. Solovov, A. Hitachi, V. Chepel, M. I. Lopes

First observation of liquid xenon scintillation due to alpha-particles and gamma-rays with a large area avalanche photodiode immersed in the liquid is reported. An energy resolution of 10% (FWHM) and a coincidence time resolution of less then 1 ns (FWHM) were measured with 5.5 MeV alpha-particles and 511 keV gamma-rays, respectively. The quantum efficiency o

G. Annino, M. Cassettari, M. Martinelli

The basic theory underlying the realization of simple multiple-band non-homogeneous dielectric resonators, whose spectral response is the overlap of single-resonator frequency bands, is developed exploiting a general approach discussed in the previous companion paper. The limit frequencies of the proposed devices, given only by the dielectric properties of t

G. Annino, M. Cassettari, M. Martinelli

Several basic properties of homogeneous planar Whispering Gallery dielectric resonators are investigated through a general approach. In particular the values for the minimum and maximum allowed radius, defined by irradiation and dielectric losses, respectively, are obtained in terms of the complex dielectric constant of the involved media. The same approach

Tony D. Roberts, Alexander D. Cronin, David A. Kokorowski, David E. Pritchard

We have measured the index of refraction for sodium de Broglie waves in gases of Ar, Kr, Xe, and nitrogen over a wide range of sodium velocities. We observe glory oscillations -- a velocity-dependent oscillation in the forward scattering amplitude. An atom interferometer was used to observe glory oscillations in the phase shift caused by the collision, which

P. I. Fomin, A. P. Fomina, V. N. Malnev

We determine the conditions of formation of spontaneous polarization phase transition to the superradiance regime in the inverted system of nonrelativistic electrons on equidistant Landau levels in rarefied magnetized plasma. The possibility of realization of such conditions in the lower Jupiter magnetosphere is shown. The effect of cyclotron superradiance o

V. P. Likhachev, J. Mesa, J. D. T. Arruda-Neto, B. V. Carlson

We present the result of a theoretical study of inclusive quasi free electrofission of $^{238}$U. The off-shell $ $cross sections for the quasi free reaction stage have been calculated within the Plane Wave Impulse Approximation (PWIA), using a Macroscopic -Microscopic description of the proton and neutron single particle momentum distributions. Electron wav

S. A. Chin, C. R. Chen

We show that the method of factorizing the evolution operator to fourth order with purely positive coefficients, in conjunction with Suzuki&#39;s method of implementing time-ordering of operators, produces a new class of powerful algorithms for solving the Schroedinger equation with time-dependent potentials. When applied to the Walker-Preston model of a dia

Y. Zhang

By means of the quark mass density- and temperature- dependent model, it is found that the negative charge and the higher strangeness fraction are in favor of the stability of strange quark matter at finite temperature. A critical baryon number density n_Bc has been found. The strange quark matter is unstable when n_B < n_Bc. The charge and strangeness fract

Y. Zhang

It is found that the radius of a stable strangelet decreases as the temperature increases in a quark mass density-dependent model. To overcome this difficulty, we extend this model to a quark mass density- and temperature- dependent model in which the vacuum energy density at zero baryon density limit B depends on temperature. An ansatz is introduced and the

Bedangadas Mohanty

Fluctuations in the ratio of neutral to charged pions arising due to formation of disoriented chiral condensates (DCC) are discussed using the Phi-measure. The properties of the measure for various cases of DCC and non-DCC are discussed. The effect of detector efficiencies and other experimental factors are presented. Application of the Phi-measure to simula

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 thermal model + hadronic rescattering calculation can explain bo

Y. Koike

Level structure of 9Be is investigated calculating poles of the alpha alphar n three-body scattering amplitude in the complex energy plane. We find 10 levels, which make rotational bands in both positive and negative parities. All of them, except 7/2^+, have been observed experimentally and the corresponding positions and widths reasonably well matched. The

F. Delduc, A. S. Sorin

Lax pair and Hamiltonian formulations of the N=4 supersymmetric Toda chain (KdV) hierarchy in N=4 superspace are proposed. The general formulae for the infinite tower of its bosonic flows in terms of the Lax operator in N=4 superspace are derived. A new N=4 superfield basis in which the flows are local is constructed and its embedding in the N=4 O(4) superco

Michael Schanz, Axel Pelster

We apply the synergetic elimination procedure for the stable modes in nonlinear delay systems close to a dynamical instability and derive the normal form for the delay-induced Hopf bifurcation in the Wright equation. The resulting periodic orbit is confirmed by numerical simulations.

Jeff Porter, Mary Silber

We exploit the presence of approximate (broken) symmetries to obtain general scaling laws governing the process of pattern formation in weakly damped Faraday waves. Specifically, we consider a two-frequency forcing function and trace the effects of time translation, time reversal and Hamiltonian structure for three illustrative examples: hexagons, two-mode s

Michael Baake

Mathematical diffraction theory is concerned with the analysis of the diffraction measure of a translation bounded complex measure $ω$. It emerges as the Fourier transform of the autocorrelation measure of $ω$. The mathematically rigorous approach has produced a number of interesting results in the context of perfect and random systems, some of which are sum

Tom Braden

We give a complete quiver description of the category of perverse sheaves on Hermitian symmetric spaces in types A and D, constructible with respect to the Schubert stratification. The calculation is microlocal, and uses the action of the Borel group to study the geometry of the conormal variety.

O Costin, S Tanveer

We prove existence and uniqueness results for nonlinear third order partial differential equations of the form $$ f_t - f_{yyy} = \sum_{j=0}^3 b_j (y, t; f) ~f^{(j)} + r(y, t) $$ where superscript $j$ denotes the $j$-th partial derivative with respect to $y$. The inhomogeneous term $r$, the coefficients $b_j$ and the initial condition $f(y,0)$ are required t

Vladimir Turaev

We introduce a norm on the real 1-cohomology of finite 2-complexes determined by the Euler characteristics of graphs on these complexes. We also introduce twisted Alexander-Fox polynomials of groups and show that they give rise to norms on the real 1-cohomology of groups. Our main theorem states that for a finite 2-complex X, the norm on H^1(X; R) determined

Aureli Alabert, Marco Ferrante

We consider linear n-th order stochastic differential equations on [0,1], with linear boundary conditions supported by a finite subset of [0,1]. We study some features of the solution to these problems, and especially its conditional independence properties of Markovian type.

Juan-Pablo Ortega, Tudor S. Ratiu

The presence of symmetries in a Hamiltonian system usually implies the existence of conservation laws that are represented mathematically in terms of the dynamical preservation of the level sets of a momentum mapping. The symplectic or Marsden--Weinstein reduction procedure takes advantage of this and associates to the original system a new Hamiltonian syste

O. Arratia, M. A. del Olmo

We present the q-deformed counterpart of the local representations of the (1+1) extended Galilei group. These representations act on the space of wavefunctions defined in the space-time. As in the classical case the q-local representations are reducible and the condition of irreducibility is given by the q-Casimir equation that in the limit of the deformatio

Paul-Andi Nagy

We consider strict and complete nearly Kaehler manifolds with the canonical Hermitian connection. The holonomy representation of the canonical Hermitian connection is studied. We show that a strict and complete nearly Kaehler is locally a Riemannian product of homogenous nearly Kaehler spaces, twistor spaces over quaternionic Kaehler manifolds and 6-dimensio

Roland Berger, Michel Dubois-Violette, Marc Wambst

Various concepts associated with quadratic algebras admit natural generalizations when the quadratic algebras are replaced by graded algebras which are finitely generated in degree 1 with homogeneous relations of degree N. Such algebras are referred to as {\sl homogeneous algebras of degree N}. In particular it is shown that the Koszul complexes of quadratic

Mutsuo Oka

We give a complete classsification of reduced sextics of torus type with configurations of the singularities and the geometry of the components.

O Costin, R D Costin

In this paper we study the asymptotic behavior for large argument of a family of solutions of the Painlevé equation P$_{\rm VI} arising in the context of Random Matrix Theory [1]. We show this family of solutions are uniquely determined by their asymptotic properties.

B. Feigin, E. Feigin

Let $π_1,...,π_n$ be an irreducible finite-dimensional $\mathfrak{sl}_2$-modules. Using the theory of the representations of the current algebras, we introduce a several ways to construct a $q$-grading on $π_1\otimes...\otimesπ_n$. We study the corresponding graded modules and prove, that they are essentially the same.

E. Liz, M. Pinto, G. Robledo, V. Tkachenko

We prove that the well-known 3/2 stability condition established for the Wright equation (WE) still holds if the nonlinearity $p(\exp(-x)-1)$ in WE is replaced by a decreasing or unimodal smooth function f with $f&#39;(0)<0$ satisfying the standard negative feedback and below boundedness conditions and having everywhere negative Schwarz derivative.

A. Pajitnov

Let $M$ be a closed connected manifold, $f$ be a Morse map from $M$ to a circle, $v$ be a gradient-like vector field satisfying the transversality condition. The Novikov construction associates to these data a chain complex $C_*=C_*(f,v)$. There is a chain homotopy equivalence between $C_*$ and completed simplicial chain complex of the corresponding infinite

Michael Roitman

In this paper we develop a formalism for working with twisted realizations of vertex and conformal algebras. As an example, we study realizations of conformal algebras by twisted formal power series. The main application of our technique is the construction of a very large family of representations for the vertex superalgebra $\goth V_Λ$ corresponding to an

Erik Bedos, Roberto Conti

We initiate a study of infinite tensor products of projective unitary representations of a discrete group G. Special attention is given to regular representations twisted by 2-cocycles and to projective representations associated with CCR-representations of bilinear maps. Detailed computations are presented in the case where G is a finitely generated free ab

J. Kowalski-Glikman, S. Nowak

Doubly Special Relativity (DSR) theory is a theory with two observer-independent scales, of velocity and mass (or length). Such a theory has been proposed by Amelino--Camelia as a kinematic structure which may underline quantum theory of relativity. Recently another theory of this kind has been proposed by Magueijo and Smolin. In this paper we show that both

David Langlois, Lorenzo Sorbo

We consider cosmological two-brane models with AdS bulk, for which the radion, i.e. the separation between the two branes, is time dependent. In the case of two de Sitter branes (including Minkowski branes as a limiting case), we compute explicitly, without any approximation, the effective four-dimensional action for the radion. With the scale factor on-shel

B. Abdesselam, A. Chakrabarti, J. Rizos, D. H. Tchrakian

An iterative construction of higher order Einstein tensors for a maximally Gauss-Bonnet extended gravitational Lagrangian was introduced in a previous paper. Here the formalism is extended to non-factorisable metrics in arbitrary ($d+1$) dimensions in the presence of superposed Gauss-Bonnet terms. Such a generalisation turns out to be remarkably convenient a

Rudolf A. Frick

In this paper we extend our previous result on the description of the partcle motion in a generalized Heisenberg picture to a relativistic fermion. The operators of the Lorentz algebra in this picture may be regarded as field operators. In this approach the transition amplitudes for the particle are constructed in terms of two-component functions in the unit

George Tsoupros

In a series of three projects a new technique which allows for higher-loop renormalisation on a manifold with boundary has been developed and used in order to assess the effects of the boundary on the dynamical behaviour of the theory. Commencing with a conceptual approach to the theoretical underpinnings of the, underlying, spherical formulation of Euclidea

H. Arthur Weldon

The analytic properties in the energy variable k_{0} of finite-temperature self-energies are investigated. A typical branch cut results from n particles being emitted into the heat bath and n&#39; being absorbed from the heat bath. There are three main results: First, in addition to the branch points at which the cuts terminate, there are also branch points

J. O. Eeg, K. Kumericki, I. Picek

We consider the double-radiative decays of heavy-light QED and QCD atoms, $μ^+ e^- \to γγ$ and $\bar{B}^{0}_s \to γγ$. Especially, we take under scrutiny contributions coming from operators that vanish on the free-quark mass shell. We show that by field redefinitions these operators are converted into contact terms attached to the bound state dynamics. A net

Stephan Narison

I summarize our self-contained determinations of the lowest order hadronic contributions to the anomalous magnetic moments a_{μ,τ} of the muon and tau leptons, the running QED coupling α(M_Z) and the muonium hyperfine splitting ν. Using as a revised estimate of the light-by light scattering: a_μ(LL)=85(18) 10^{-11}, we deduce: a_μ^{SM} = 116 591 861(78) 10^{

A. Szczurek

We discuss several mechanisms of heavy quark production in (real) photon-nucleon and (real) photon - (real) photon collisions. In particular we focuse on application of the Saturation Model. We discuss how to generalize the formula from virtual photon - proton scattering and analyze threshold effects. We discuss a possibility to measure the cross section for

Johan Bijnens, Pere Talavera

We study the electromagnetic form factor of the pion and kaons at low-energies with the use of Chiral Perturbation Theory. The analysis is performed within the three flavour framework and at next-to-next-to-leading order. We explain carefully all the relevant consistency checks on the expressions, present full analytical results for the pion form factor and

A. Bialas

It is pointed out that the recent data on charge fluctuations observed in heavy ion collisions are compatible with production of a system of weakly correlated constituent quarks and antiquarks.

T. M. Aliev, A. Ozpineci, M. Savci

We study lepton polarization asymmetries in the (Lambda_b -> Lambda l^+ l^-) decay using the most general model independent effective Hamiltonian. The dependence of the lepton polarizations and their combinations on the new Wilson coefficients are studied in detail. It is observed that there is a region for the new Wilson coefficients for which the branching

Alessandra Retico

We analyse the sensitivity to physics beyond the SM of T-odd correlations in $K_{\ell 4}$ decays, which do not involve the lepton polarization. We show that a combined analysis of $K^+_{μ4}$ and $K^-_{μ4}$ decays can lead to new constraints about CP violation in $ΔS=1$ charged-current interactions, complementary to those obtained from the transverse muon pol

Neven Bilic, Gary B. Tupper, Raoul D. Viollier

After a brief introduction to standard cosmology and the dark matter problem in the the Universe, we consider a self-gravitating noninteracting fermion gas at nonzero temperature as a model for the dark matter halo of the Galaxy. This fermion gas model is then shown to imply the existence of a supermassive compact dark object at the Galactic center.

Shoichi Ichinose

The Kaluza-Klein theory and Randall-Sundrum theory are examined comparatively, with focus on the five dimensional (Dirac) fermion and the dimensional reduction to four dimensions. They are treated in the Cartan formalism. The chiral property, localization, anomaly phenomena are examined. The electric and magnetic dipole moment terms naturally appear. The ord

Chris Allton

A brief overview of the lattice technique of studying QCD is presented. Recent results from the UKQCD Collaboration&#39;s simulations with dynamical quarks are then presented. In this work, the calculations are all at a fixed lattice spacing and volume, but varying sea quark mass from infinite (corresponding to the quenched simulation) down to roughly that o

K. R. S. Balaji, A. Dighe, R. N. Mohapatra

We point out that the presence of bulk neutrinos in models with large extra spatial dimensions can lead to observable flavour specific deformations in the spectra of extreme high energy cosmic neutrinos. These deformations are due to the spin precession of the high energy neutrinos in the background magnetic fields via electromagnetic interactions. Measureme

F. Palombi, R. Petronzio, A. Shindler

A non perturbative computation of the evolution of singlet parton densities without gauge--fixing requires a gauge invariant gluon source operator. Within the Schrödinger Functional scheme (SF), such a source can be defined in terms of path ordered products of gauge links, connected to the time boundaries. In this paper we adopt this definition and perform a

The BaBar Collaboration, B. Aubert

We report a measurement of the branching fraction of the decay B^0 --> D^{*+} D^{*-} and of the CP-odd component of its final state using the BaBar detector. With data corresponding to an integrated luminosity of 20.4 fb^{-1} collected at the Upsilon(4S) resonance during 1999-2000, we have reconstructed 38 candidate signal events in the mode B^0 --> D^{*+}D^

B. Aubert, BABAR Collaboration

We present updated results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 62 million Upsilon(4S) --> B anti-B decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. In this sample we study events in which one neutral

GDH-, A2-Collaborations, :, J. Ahrens

The helicity dependence of the $\vecγ \vec{p} \to p π^0$ reaction has been measured for the first time in the photon energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4$π$-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. These data are predominantly s

Sawa Manoff

Basic notions and mathematical tools in continuum media mechanics are recalled. The notion of exponent of a covariant differential operator is introduced and on its basis the geometrical interpretation of the curvature and the torsion in $(\bar{L}_n,g)$-spaces is considered. The Hodge (star) operator is generalized for $(\bar{L}_n,g)$-spaces. The kinematic c

Reginald T. Cahill

Progress in the new information-theoretic process physics is reported in which the link to the phenomenology of general relativity is made. In process physics the fundamental assumption is that reality is to be modelled as self-organising semantic (or internal or relational) information using a self-referentially limited neural network model. Previous progre

Yan Zhang

Prioritized default reasoning has illustrated its rich expressiveness and flexibility in knowledge representation and reasoning. However, many important aspects of prioritized default reasoning have yet to be thoroughly explored. In this paper, we investigate two properties of prioritized logic programs in the context of answer set semantics. Specifically, w

J. P. Delgrande, T. Schaub, H. Tompits

We introduce a methodology and framework for expressing general preference information in logic programming under the answer set semantics. An ordered logic program is an extended logic program in which rules are named by unique terms, and in which preferences among rules are given by a set of atoms of form s < t where s and t are names. An ordered logic pro

S. Vakhrushev, S. Shapiro

Inelastic neutron scattering measurements of the relaxor ferroelectric PbMg$_{1 / 3}$Nb$_{2 / 3}$O$_{3}$ (PMN) in the temperature range 490~K$<$T$<$880~K directly observe the soft mode (SM) associated with the Curie-Weiss behavior of the dielectric constant $\varepsilon $(T). The results are treated within the framework of the coupled SM and transverse optic

I. G. Deac, S. V. Diaz, B. G. Kim, S. -W. Cheong

We have studied the magnetic relaxation properties of the phase-separated manganite compound La0.250Pr0.375Ca0.375MnO3 . A series of polycrystalline samples was prepared with different sintering temperatures, resulting in a continuous variation of phase fraction between metallic (ferromagnetic) and charge-ordered phases at low temperatures. Measurements of t

H. J. Lee, K. H. Kim, M. W. Kim, T. W. Noh

We investigated temperature (T)- and magnetic field-dependent optical conductivity spectra (\s\w) of a La_5/8-yPr_yCa_3/8MnO_3 (y~0.35) single crystal, showing intriguing phase coexistence at low T. At T_C < T < T_CO, a dominant charge-ordered phase produces a large optical gap energy of ~0.4 eV. At T < T_C, at least two absorption bands newly emerge below 0

A. L. Ankudinov, A. I. Nesvizhskii, J. J. Rehr

Calculations of L-shell x-ray absorption in transition metals are shown to be sensitive to screening, both of the x-ray field and the photoelectron-core hole interaction. This screening is calculated using a generalization of the time dependent local density approximation and a projection onto a local atomic basis. The approach yields renormalized dipole-mat

Pasquale Calabrese, Andrea Gambassi

We study the off-equilibrium response and correlation functions and the corresponding fluctuation-dissipation ratio for a purely dissipative relaxation of an O(N) symmetric vector model (Model A) below its upper critical dimension. The scaling behavior of these quantities is analyzed and the associated universal functions are determined at first order in eps

T. Karpiuk, M. Brewczyk, L. Dobrek, M. A. Baranov

We analyze, the generation of soliton-like solutions in a single-component Fermi gas of neutral atoms at zero and finite temperatures with the phase imprinting method. By using both the numerical and analytical calculations, we find the conditions when the quasisolitons, which apparently resamble the properties of solitons in non-linear integrable equations,

Juan R. Sanchez

The scaling properties of one-dimensional deconstructed surfaces are studied by numerical simulations of a disaggregation model. The model presented here for the disaggregation process takes into account the possibility of having quenched disorder in the bulk under deconstruction. The disorder can be considered to model several types of irregularities appear

A. J. Briant, P. Papatzacos, J. M. Yeomans

We use a lattice Boltzmann algorithm for liquid-gas coexistence to investigate the steady state interface profile of a droplet held between two shearing walls. The algorithm solves the hydrodynamic equations of motion for the system. Partial wetting at the walls is implemented to agree with Cahn theory. This allows us to investigate the processes which lead

Gerald Paul, Shlomo Havlin, H. Eugene Stanley

Using Monte-Carlo simulations, we determine the scaling form for the probability distribution of the shortest path, $\ell$, between two lines in a 3-dimensional percolation system at criticality; the two lines can have arbitrary positions, orientations and lengths. We find that the probability distributions can exhibit up to four distinct power law regimes (

L. Acedo, S. B. Yuste

We investigate the first passage time t_{j,N} to a given chemical or Euclidean distance of the first j of a set of N>>1 independent random walkers all initially placed on a site of a disordered medium. To solve this order-statistics problem we assume that, for short times, the survival probability (the probability that a single random walker is not absorbed

E. del Barco, M. Duran, J. M. Hernandez, J. Tejada

We have carried out in ferritin the Field-Cooling method and data analysis proposed by Mamiya et al. (Phys. Rev. Lett. 88, 67202 (2002) at T = 5 K in order to check the time magnetic relaxation of these antiferromagnetic nanoparticles as a function of the magnetic field. We found that relaxation at T = 5 K in ferritin is faster in the absence of magnetic fie

B. J. Powell, James F. Annett, B. L. Gyorffy

We investigate the order parameter of Sr$_2$RuO$_4$ in an exchange-only magnetic field. A Ginzburg-Landau symmetry analysis implies three possibilities: a pure $^3$He A phase, a $^3$He A$_1$ or a $^3$He A$_2$ phase. We explore the exchange field dependence of the order parameter and energy gap in a one-band model of Sr$_2$RuO$_4$. The numerical solutions sho

T. Markovich, E. Polturak, J. Bossy, E. Farhi

We report neutron scattering measurements of the phonons in bcc solid 4He. In general, only 3 accoustic phonon branches should exist in a monoatomic cubic crystal. In addition to these phonon branches, we found a new &#39;&#39;optic-like&#39;&#39; mode along the [110] direction. One possible interpretation of this new mode is in terms of localized excitation

O. K. Andersen, T. Saha-Dasgupta, S. Ezhov

By the example of sp^3-bonded semiconductors, we illustrate what 3rd-generation muffin-tin orbitals (MTOs) are. We demonstrate that they can be downfolded to smaller and smaller basis sets: sp^3d^10,sp^3, and bond orbitals. For isolated bands, it is possible to generate Wannier functions a priori. Also for bands, which overlap other bands, Wannier-like MTOs

G. G. Batrouni, V. Rousseau, R. T. Scalettar, M. Rigol

In the absence of a confining potential, the boson Hubbard model in its ground state is known to exhibit a superfluid to Mott insulator quantum phase transition at commensurate fillings and strong on-site repulsion. In this paper, we use quantum Monte Carlo simulations to study the ground state of the one dimensional bosonic Hubbard model in a trap. We show

E. K. O. Hellén, J. Krug

Coarsening of sand ripples is studied in a one-dimensional stochastic model, where neighboring ripples exchange mass with algebraic rates, $Γ(m) \sim m^γ$, and ripples of zero mass are removed from the system. For $γ< 0$ ripples vanish through rare fluctuations and the average ripples mass grows as $\avem(t) \sim -γ^{-1} \ln (t)$. Temporal correlations decay

Byounghak Lee, T. Jungwirth, A. H. MacDonald

Diluted magnetic semiconductors (DMSs), in which magnetic elements are substituted for a small fraction of host elements in a semiconductor lattice, can become ferromagnetic when doped. In this article we discuss the physics of DMS ferromagnetism in systems with semiconductor heterojunctions. We focus on the mechanism that cause magnetic and magnetoresistive

D. Andrienko, M. P. Allen

Molecular simulations of a nematic liquid crystal confined in cylinder geometry with homeotropic anchoring have been carried out. The core structure of a disclination line defect of strength +1 has been examined, and comparison made with various theoretical treatments, which are presented in a unified way. It is found that excellent fits to the cylindrically

Dragi Karevski

We consider the nonequilibrium time evolution of the transverse magnetization in the critical Ising and $XX$ quantum chains. For some inhomogeneously magnetized initial states we derive analytically the transverse magnetization profiles and show that they evolve into scaling forms in the long-time limit. In particular it is seen that the Ising chain exhibits

Abhishek Dhar

A finite Green-Kubo thermal conductivity in a one-dimensional momentum conserving system was reported recently by Garrido et al [Phys. Rev. Lett., vol. 86, 5486 (2001)]. We first comment on the apparent contradiction with an earlier result of Prosen and Campbell [Phys. Rev. Lett., vol. 84, 2857 (2000)]. We then point out certain inconsistencies in their resu

C. Stock, W. J. L. Buyers, Z. Tun, R. Liang

We present elastic and inelastic neutron scattering results on highly oxygen ordered YBa2Cu3O6.5 ortho-II. We find no evidence for the presence of ordered magnetic moments to a sensitivity of 0.003 Bohr magnetons, an order of magnitude smaller than has been suggested in theories of orbital or d-density-wave (DDW) currents. The absence of sharp elastic peaks,

R. Budakian, S. J. Putterman

Data from an instrument that measures conductance, stiffness and rupture strength of junctions indicates that when two macroscopic metal surfaces are brought into contact a nanometer size junction spontaneously forms over a long time scale (~ 60 s). Furthermore, the parameters of junction rupture match the observed dynamics of stick-slip friction. This sugge

Gonzalo Usaj, Harold U. Baranger

We study the statistics of the spacing between Coulomb blockade conductance peaks in quantum dots with large dimensionless conductance g. Our starting point is the ``universal Hamiltonian&#39;&#39;--valid in the g->oo limit--which includes the charging energy, the single-electron energies (described by random matrix theory), and the average exchange interact

Yasser Roudi, Shahin Rouhani

It is shown that long term behavior of two connected Integrate- and- Fire neurons with excitatory synapses is determined by some fixed-points. In the case of equal synaptic weights four different dynamic phases are found. Between these phases there is a specific phase with a global attractor fixed-point, which is of interest from different viewpoints. Simula

P. Coleman, W. Mao

Using a quantum generalization of the Onsager principle of microscopic reversibility, the magnetization of a system in a non-equilibrium steady state quantum dot is formulated as a response of the interaction energy to an external field. This formulation permits a direct and compact computation of the steady-state magnetization of a non-equilibrium quantum d