December 2007 arXiv papers — page 47

Andrea Gregori

The natural evolution of life seems to proceed through steps characterized by phases of relatively rapid changes, followed by longer, more stable periods. In the light of the string-theory derived physical scenario proposed in [1], we discuss how this behaviour can be related to a sequence of resonances of the energy of natural sources of radiation and absor

E. G. Galkina, A. Yu. Galkin, B. A. Ivanov

Isotropic antiferromagnets shows a reach variety of magnetic solitons with non-trivial static and dynamic properties. One-dimensional soliton elementary excitations have a periodic dispersion law. For two-dimensional case, planar antiferromagnetic vortices having non-singular macroscopic core with the saturated magnetic moment are present. The dynamic proper

Jean Bérard, Didier Piau

We define a notion of coupling time with ambiguities for interacting particle systems, and show how this can be used to prove ergodicity and to bound the convergence time to equilibrium and the decay of correlations at equilibrium. A motivation is to provide simple conditions which ensure that perturbed particle systems share some properties of the underlyin

M. Di Toro, M. Colonna, G. Ferini, V. Greco

We show that the phenomenology of isospin effects on heavy ion reactions at intermediate energies (few AGeV range) is extremely rich and can allow a ``direct'' study of the covariant structure of the isovector interaction in a high density hadron medium. We work within a relativistic transport frame, beyond a cascade picture, consistently derived fro

Luc Vinet, Alexei Zhedanov

Assume that there is a set of monic polynomials $P_n(z)$ satisfying the second-order difference equation $$ A(s) P_n(z(s+1)) + B(s) P_n(z(s)) + C(s) P_n(z(s-1)) = λ_n P_n(z(s)), n=0,1,2,..., N$$ where $z(s), A(s), B(s), C(s)$ are some functions of the discrete argument $s$ and $N$ may be either finite or infinite. The irreducibility condition $A(s-1)C(s) \ne

Tetsuo Deguchi

We discuss a conjecture that the twisted transfer matrix of the six-vertex model at roots of unity with some discrete twist angles should have the sl(2) loop algebra symmetry. As an evidence of this conjecture, we show the following mathematical result on a subalgebra of the sl(2) loop algebra, which we call a Borel subalgebra: any given finite-dimensional h

Antonio Bianconi

Experimental results obtained by using x-ray absorption spectroscopy show that the configurations of Cu sites in the CuO2 plane of Bi 2:2:1:2 high Tc superconductors are not homogeneous. Different Cu sites are characterized by short 0.23 nm and long 0.245 nm Cu-O(apical) distances. The linear arrays of different Cu sites forming domains with a corrugated-iro

Antti Kemppinen, Antti J. Manninen, Mikko Möttönen, Juha J. Vartiainen

We present an experimental study of the magnetic flux dependence of the critical current of a balanced SQUID with three Josephson junctions in parallel. Unlike for ordinary dc SQUIDs, the suppression of the critical current does not depend on the exact parameters of the Josephson junctions. The suppression is essentially limited only by the inductances of th

M. K. Suleymanov, E. U. Khan, A. Kravchakova, Mahnaz Q. Haseeb

We discuss the experimental results on the behavior of the average multiplicities and angular distributions of slow particles emitted in hadron-nuclear and nuclear-nuclear interactions at relativistic energies as a function of the centrality of collisions. It is observed that by increasing the mass of the projectiles the angular distributions of slow particl

Antonio Bianconi

The case of a Feshbach shape resonance in the pairing mechanism for high T c superconductivity in a crystalline lattice of doped metallic nanotubes is described. The superlattice of doped metallic nanotubes provides a superconductor with a strongly asymmetric gap. The disparity and different spatial locations of the wave functions of electrons in different s

Yuriy Reznik

We study the effects of finite-precision representation of source's probabilities on the efficiency of classic source coding algorithms, such as Shannon, Gilbert-Moore, or arithmetic codes. In particular, we establish the following simple connection between the redundancy $R$ and the number of bits $W$ necessary for representation of source's probabi

Boris Kolev

Let f be an orientation preserving homeomorphism of the disc D2 which possesses a periodic point of period 3. Then either f is isotopic, relative the periodic orbit, to a homeomorphism g which is conjugate to a rotation by 2 pi /3 or 4 pi /3, or f has a periodic point of least period n for each n in N*.

Aurélien Manchon, Natalya Ryzhanova, A. Vedyayev, Mairbek Chschiev

A free electron description of spin-dependent tranport in magnetic tunnel junctions with non collinear magnetizations is presented. We investigate the origin of transverse spin density in tunnelling transport and the quantum interferences which give rise to oscillatory torques on the local magnetization. Spin transfer torque is also analyzed and an important

Boris Kolev, David H. Sattinger

We describe the Hamiltonian structures, including the Poisson brackets and Hamiltonians, for free boundary problems for incompressible fluid flows with vorticity. The Hamiltonian structure is used to obtain variational principles for stationary gravity waves both for irrotational flows as well as flows with vorticity.

M. V. Antipov

Number of results in number theory have been developed using a new method. The Goldbach binary conjecture in strengthened formulation have been among them.

U. Jamil, J. K. Sarma

Evolution of gluon distribution function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equation in next-to-leading order (NLO) at low-x is presented assuming the Regge behaviour of quarks and gluons at this limit. We compare our results of gluon distribution function with MRST2004, GRV98LO and GRV98NLO parameterizations and show the compa

S. C. Hendy, N. J. Lund

We study slip boundary conditions for simple fluids at surfaces with nanoscale chemical heterogeneities. Using a perturbative approach, we examine the flow of a Newtonian fluid far from a surface described by a heterogeneous Navier slip boundary condition. In the far-field, we obtain expressions for an effective slip boundary condition in certain limiting ca

F. Roig, A. O. Ribeiro, R. Gil-Hutton

We present a comparative analysis of the spectral slope and color distributions of Jupiter Trojans, with particular attention to asteroid families. We use a sample of data from the Moving Object Catalogue of the Sloan Digital Sky Survey, together with spectra obtained from several surveys. A first sample of 349 observations, corresponding to 250 Trojan aster

Kimball A. Milton, Ines Cavero-Pelaez, Prachi Parashar, K. V. Shajesh

The construction of $\mathcal{PT}$-symmetric quantum electrodynamics is reviewed. In particular, the massless version of the theory in 1+1 dimensions (the Schwinger model) is solved. Difficulties with unitarity of the $S$-matrix are discussed.

Tao Wang

By analyzing the BCS-BEC crossover, I found that because of the pairing interactions,a continuous family of quantum statistics interpolating between fermions and bosons is possible, although it seems incapable to construct reasonable wave function.

Matthew R. McKay, Peter J. Smith, Himal A. Suraweera, Iain B. Collings

This paper considers the distribution of the mutual information of frequency-selective spatially-uncorrelated Rayleigh fading MIMO channels. Results are presented for OFDM-based spatial multiplexing. New exact closed-form expressions are derived for the variance of the mutual information. In contrast to previous results, our new expressions apply for systems

Yun Wang

Illuminating the nature of dark energy is one of the most important challenges in cosmology today. In this review I discuss several promising observational approaches to understanding dark energy, in the context of the recommendations by the U.S. Dark Energy Task Force and the ESA-ESO Working Group on Fundamental Cosmology.

Florian Schiller, Norbert Przybilla

Quantitative spectroscopy of luminous BA-type supergiants offers a high potential for modern astrophysics. The degree to which we can rely on quantitative studies of this class of stars as a whole depends on the quality of the analyses for benchmark objects. We constrain the basic atmospheric parameters and fundamental stellar parameters as well as chemical

B. Julia-Diaz

Recent developments on a dynamical coupled-channels model of hadronic and electromagnetic production of nucleon resonances are summarized.

D. Marcillac, G. H. Rieke, C. Papovich, C. N. A. Willmer

We investigate the environment of infrared luminous galaxies (L$_{IR}$[8-1000 $μ$m$] >10^{11}$L$_{\sun}$). We focus on the redshift range 0.7 $\leq$ z $\leq$ 1, where these galaxies dominate the star formation activity and play a significant role in galaxy evolution. We employ MIPS 24$μ$m data to identify infrared galaxies in the Extended Groth Strip (EGS).

Nicholas P. Bailey, Tage Christensen, Bo Jakobsen, Kristine Niss

We first summarize the classical arguments that the vast majority of glass-forming liquids require more than one "order" parameter for their description. Critiques against this conventional wisdom are then presented, and it is argued that the matter deserves to be reconsidered in light of recent experimental developments. Out of the eight basic therm

Silvia Faggian

The paper concerns the study of equilibrium points, namely the stationary solutions to the closed loop equation, of an infinite dimensional and infinite horizon boundary control problem for linear partial differential equations. Sufficient conditions for existence of equilibrium points in the general case are given and later applied to the economic problem o