July 2006 arXiv papers — page 13

R. Carls, D. Kohel, D. Lubicz

We find equations for the higher dimensional analogue of the modular curve X_0(3) using Mumford's algebraic formalism of algebraic theta functions. As a consequence, we derive a method for the construction of genus 2 hyperelliptic curves over small degree number fields whose Jacobian has complex multiplication and good ordinary reduction at the prime 3.

R. de la Madrid

The spectrum of a quantum system has in general bound, scattering and resonant parts. The Hilbert space includes only the bound and scattering spectra, and discards the resonances. One must therefore enlarge the Hilbert space to a rigged Hilbert space, within which the physical bound, scattering and resonance spectra are included on the same footing. In thes

D. Maslov, D. M. Miller, G. W. Dueck

This paper presents novel techniques for the synthesis of reversible networks of Toffoli gates, as well as improvements to previous methods. Gate count and technology oriented cost metrics are used. Our synthesis techniques are independent of the cost metrics. Two new iterative synthesis procedure employing Reed-Muller spectra are introduced and shown to com

Peter Morgan

A quantum field model for an experiment describes thermal fluctuations explicitly and quantum fluctuations implicitly, whereas a comparable continuous random field model would describe both thermal and quantum fluctuations explicitly. An ideal classical measurement does not affect the results of later measurements, in contrast to ideal quantum measurements,

M. A. Jafarizadeh, M. Rezaeen, S. Ahadpour

Following the linear programming prescription of Ref. \cite{PRA72}, the $d\otimes d$ Bell diagonal entanglement witnesses are provided. By using Jamiolkowski isomorphism, it is shown that the corresponding positive maps are the generalized qudit Choi maps. Also by manipulating particular $d\otimes d$ Bell diagonal separable states and constructing correspond

R S Said, M R B Wahiddin, B A Umarov

We propose an alternative scheme to generate W state via optical state truncation using quantum scissors. In particular, these states may be generated through three-mode optical state truncation in a Kerr nonlinear coupler. The more general three-qubit state may be also produced if the system is driven by external classical fields.

S. M. Roy, Samuel L. Braunstein

We show that when a suitable entanglement generating unitary operator depending on a parameter is applied on N qubits in parallel, and an appropriate observable is measured, a precision of order 2 raised to the power (-N) in estimating the parameter may be achieved. This exponentially improves the precision achievable in classical and in quantum non-entangli

D. Elser, U. L. Andersen, A. Korn, O. Gloeckl

Guided Acoustic Wave Brillouin Scattering (GAWBS) generates phase and polarization noise of light propagating in glass fibers. This excess noise affects the performance of various experiments operating at the quantum noise limit. We experimentally demonstrate the reduction of GAWBS noise in a photonic crystal fiber in a broad frequency range using cavity sou

E. Novais, Harold U. Baranger

We study the decoherence of a quantum computer in an environment which is inherently correlated in time and space. We first derive the nonunitary time evolution of the computer and environment in the presence of a stabilizer error correction code, providing a general way to quantify decoherence for a quantum computer. The general theory is then applied to th

Vladan Pankovic, Banjac Dejan, Rade Glavatovic, Milan Predojevic

In this work we consider a simple, approximate, tending toward exact, solution of the system of two usual Lotka-Volterra differential equations. Given solution is obtained by an iterative method. In any finite approximation order of this solution, exponents of the corresponding Lotka-Volterra variables have simple, time polynomial form. When approximation or

Simon Parkin, Gregor Knoener, Timo A. Nieminen, Norman R. Heckenberg

We describe a way to determine the total angular momentum, both spin and orbital, transferred to a particle trapped in optical tweezers. As an example an LG02 mode of a laser beam with varying degrees of circular polarisation is used to trap and rotate an elongated particle with a well defined geometry. The method successfully estimates the total optical tor

Anthony R. Gorges, Ansel J. Foxley, David M. French, Christopher M. Ryan

Reabsorption, the multiple scattering of spontaneously emitted photons in optically thick gases, is a major limitation to efficient optical pumping and laser cooling in ultracold gases. We report mitigation of reabsorption using spatial and frequency modulation of laser light illuminating such gases. We developed a semi-classical model that successfully desc

Jean-Philippe Groby, Laurent De Ryck, Philippe Leclaire, Armand Wirgin

A domain integral method employing a specific Green's function (i.e., incorporating some features of the global problem of wave propagation in an inhomogeneous medium) is developed for solving direct and inverse scattering problems relative to slab-like macroscopically inhomogeneous porous obstacles. It is shown how to numerically solve such problems, in

William Barford, Christopher D P Duffy

The cross-over from coherent to incoherent exciton transport in disordered polymer films is studied by computationally solving a modified form of the Redfield equation for the exciton density matrix. This theory models quantum mechanical (ballistic) and incoherent (diffusive) transport as limiting cases. It also reproduces Forster transport for certain param

Alessandro Pluchino, Stefano Boccaletti, Vito Latora, Andrea Rapisarda

In this paper we discuss opinion dynamics in the Opinion Changing Rate (OCR) model, recently proposed (A.Pluchino, V.Latora and A.Rapisarda Int. J. Mod. Phys. C, 16, No.4, 515-531 (2005)). The OCR model allows to study whether and how a group of social agents, with a different intrinsic tendency rate to change opinion, finds agreement. In particular, we impl

Johan F. Prins

It is argued here that the Copenhagen interpretation of quantum mechanics violates the tenets on which both Galileo's and Einstein's theories of relativity are based. It is postulated that the "building blocks" of the universe are not "particles" but are holistic wave-entitities which act and interact with other wave-entities as one w

Burra G. Sidharth

De Broglie believed that the photon has a mass, a view shared by a few others. Quite recently, the author has argued that the photon has a mass which is consistent with the latest experimental limits. In the present paper we point out that there is experimental evidence for this mass and also give a theoretical demonstration of the photon mass.

C. Liu, S. S. Liaw

In the standard minority game, every agent switches to his best strategy in hand at each time step. If only a small number of agents are allowed to switch their strategies at each time step, the population variance of the system plunges. The variance reaches a low value and remains steady for a period of time. Then without any sign it starts to rise abruptly

C. H. Hung, S. S. Liaw

It is known that the memory is relevant in the symmetric phase of the minority game. In our previous work we have successfully explained the quasi-periodic behavior of the game in the symmetric phase with the help of the probability theory. Based on this explanation, we are able to determine how the memory affects the variance of the system in this paper. By

D. Schurig, J. B. Pendry, D. R. Smith

Complex and interesting electromagnetic behavior can be found in spaces with non-flat topology. When considering the properties of an electromagnetic medium under an arbitrary coordinate transformation an alternative interpretation presents itself. The transformed material property tensors may be interpreted as a different set of material properties in a fla

C. Henning, H. Baumgartner, A. Piel, P. Ludwig

The ground state of an externally confined one-component Yukawa plasma is derived analytically. In particular, the radial density profile is computed. The results agree very well with computer simulations on three-dimensional spherical Coulomb crystals. We conclude in presenting an exact equation for the density distribution for a confinement potential of ar

L. Fortunato, S. De Baerdemacker, K. Heyde

The Bohr-Mottelson model is solved for a generic soft triaxial nucleus, separating the Bohr hamiltonian exactly and using a number of different model-potentials: a displaced harmonic oscillator in $γ$, which is solved with an approximated algebraic technique, and Coulomb/Kratzer, harmonic/Davidson and infinite square well potentials in $β$, which are solved

E. Oset, S. Sarkar, M. J. Vicente Vacas, M. Kaskulov

In this talk I present recent developments in chiral dynamics of hadrons and hadrons in a medium addressing the following points: interaction of the octet of pseudoscalar mesons with the octet of baryons of the nucleon, showing recent experimental evidence on the existence of two $Λ(1405)$ states, the interaction of the octet of pseudoscalar mesons with the

Amruta Mishra, Stefan Schramm

Isospin effects on the optical potentials of kaons and antikaons in dense hadronic matter are investigated using a chiral SU(3) model. These effects are important for asymmetric heavy ion collision experiments. In the present work the dispersion relations are derived for kaons and antikaons, compatible with the low energy scattering data, within our model ap

E. A. McCutchan, Dennis Bonatsos, N. V. Zamfir

The parameter independent (up to overall scale factors) predictions of the X(5)-$β^2$, X(5)-$β^4$, and X(3) models, which are variants of the X(5) critical point symmetry developed within the framework of the geometric collective model, are compared to two-parameter calculations in the framework of the interacting boson approximation (IBA) model. The results

J. N. Orce, J. D. Holt, A. Linnemann, C. J. McKay

The low-spin structure of 93Nb has been studied using the (n,n' gamma) reaction at neutron energies ranging from 1.5 to 3.0 MeV and the 94Zr(p,2n gamma)93Nb reaction at bombarding energies from 11.5 to 19 MeV. States at 1779.7 and 1840.6 keV, respectively, are proposed as mixed-symmetry states associated with the coupling of a proton hole in the p_1/2 or

Maciej Nieszporski, Antoni Sym

We discuss integrability of normal field equations of arbitrary parametrised Bianchi surfaces. A novel geometric definition of Bianchi surfaces is presented as well as Bäcklund transformation for the normal field equations in arbitrary chosen surface parametrization.

J. Nickel

An approach is proposed to obtain some exact explicit solutions in terms of the Weierstrass' elliptic function $\wp$ to a generalized Benjamin-Bona-Mahony (BBM) equation. Conditions for periodic and solitary wave like solutions can be expressed compactly in terms of the invariants of $\wp$. The approach unifies recently established ad-hoc methods to a ce

Eric Bedford, Sione Ma`u

We give a formula for the complex Monge-Ampere operator applied to the maximum of a finite number of functions.

Xiaonan Ma, Weiping Zhang

We generalize several recent results concerning the asymptotic expansions of Bergman kernels to the framework of geometric quantization and establish an asymptotic symplectic identification property. More precisely, we study the asymptotic expansion of the $G$-invariant Bergman kernel of the spin^c Dirac operator associated with high tensor powers of a posit

Christian Léonard

We present a general method, based on conjugate duality, for solving a convex minimization problem without assuming unnecessary topological restrictions on the constraint set. It leads to dual equalities and characterizations of the minimizers without constraint qualification. As an example of application, the Monge-Kantorovich optimal transport problem is s

Fabio Cipriani, Daniele Guido, Tommaso Isola

A class of CW-complexes, called self-similar complexes, is introduced, together with C*-algebras A_j of operators, endowed with a finite trace, acting on square-summable cellular j-chains. Since the Laplacian Delta_j belongs to A_j, L^2-Betti numbers and Novikov-Shubin numbers are defined for such complexes in terms of the trace. In particular a relation inv

Dimitrije Kostic, Catherine Yan

A parking function of length n is a sequence (b_1, b_2,..., b_n) of nonnegative integers whose nondecreasing rearrangement (a_1, a_2,...,a_n) has the property that a_i < i for every i. A well-known result about parking functions is that the polynomial P_n(q), which enumerates the complements of parking functions by the sum of their terms, is the generating f

Yoshikata Kida

We show that the mapping class group of a compact orientable surface with higher complexity has the following extreme rigidity in the sense of measure equivalence: if the mapping class group is measure equivalent to a discrete group, then they are commensurable up to finite kernel. Moreover, we describe all lattice embeddings of the mapping class group into

Kristian Bjerkloev, Tobias Jaeger

We describe the relation between the dynamical properties of a quasiperiodically forced orientation-preserving circle homeomorphism and the behavior of the fibered rotation number with respect to strictly monotone perturbations. Despite the fact that the dynamics in the forced case can be considerably more complicated, the result we obtain is in perfect anal

Mathieu Coquerelle, Jérémie Allard, Georges-Henri Cottet, Marie-Paule Cani

We present an accurate Lagrangian method based on vortex particles, level-sets, and immersed boundary methods, for animating the interplay between two fluids and rigid solids. We show that a vortex method is a good choice for simulating bi-phase flow, such as liquid and gas, with a good level of realism. Vortex particles are localized at the interfaces betwe

Rodica Toader, Chiara Zanini

We introduce a new model of irreversible quasistatic crack growth in which the evolution of cracks is the limit of a suitably modified $ε$-gradient flow of the energy functional, as the &#34;viscosity&#34; parameter $ε$ tends to zero.

Aurélien Djament

We prove that, in the category F of functors between F\_2-vector spaces, the tensor product between the second non constant standard injective functor and an exterior power functor is artinian. The only cas known to date was the artinian character of this injective ; our result is a step in the study of the third non constant standard injective. We use the d

Rasul Shafikov, Kaushal Verma

Let $M, M&#39;$ be smooth, real analytic hypersurfaces of finite type in ${\mbf C^n}$ and $\h f$ a holomorphic correspondence (not necessarily proper) that is defined on one side of $M$, extends continuously up to $M$ and maps $M$ to $M&#39;$. It is shown that $\h f$ must extend across $M$ as a locally proper holomorphic correspondence. This is a version for

G V Ravindra

Let $k$ be a field of arbitrary characteristic. Let $S$ be a singular surface defined over $k$ with multiple rational curve singularities and suppose that the Chow group of zero cycles of its normalisation $\tilde{S}$ is finite dimensional. We give numerical conditions under which the Chow group of zero cycles of $S$ is finite dimensional.

Florian Luca, Igor E Shparlinski

We study some arithmetic properties of the Ramanujan function $τ(n)$, such as the largest prime divisor $P(τ(n))$ and the number of distinct prime divisors $ω(τ(n))$ of $τ(n)$ for various sequences of $n$. In particular, we show that \hbox{$P(τ(n)) \geq (\log n)^{33/31 + o(1)}$} for infinitely many $n$, and \begin{equation*} P(τ(p)τ(p^2)τ(p^3)) > (1+o(1))\fr

Volodymyr Mazorchuk

In the first part of this paper the projective dimension of the structural modules in the BGG category $\mathcal{O}$ is studied. This dimension is computed for simple, standard and costandard modules. For tilting and injective modules an explicit conjecture relating the result to Lusztig&#39;s $\mathbf{a}$-function is formulated (and proved for type $A$). Th

Anjan Kumar Chandra, Subinay Dasgupta

According to Goldbach conjecture, any even number can be broken up as the sum of two prime numbers : $n = p + q$. We construct a network where each node is a prime number and corresponding to every even number $n$, we put a link between the component primes $p$ and $q$. In most cases, an even number can be broken up in many ways, and then we chose {\em one}

Francois Hamel, Nikolai Nadirashvili, Emmanuel Russ

Let $Ω$ be a bounded $C^{2,α}$ domain in $\R^n$ ($n\geq 1$, $0<α<1$), $Ω^{\ast}$ be the open Euclidean ball centered at 0 having the same Lebesgue measure as $Ω$, $τ\geq 0$ and $v\in L^{\infty}(Ω,\R^n)$ with $\left\Vert v\right\Vert\_{\infty}\leq τ$. If $λ\_{1}(Ω,τ)$ denotes the principal eigenvalue of the operator $-Δ+v\cdot\nabla$ in $Ω$ with Dirichlet bou

Derek W. Robinson, Adam Sikora

We analyze degenerate, second-order, elliptic operators $H$ in divergence form on $L_2({\bf R}^{n}\times{\bf R}^{m})$. We assume the coefficients are real symmetric and $a_1H_δ\geq H\geq a_2H_δ$ for some $a_1,a_2>0$ where \[ H_δ=-\nabla_{x_1} c_{δ_1, δ&#39;_1}(x_1) \nabla_{x_1}-c_{δ_2, δ&#39;_2}(x_1) \nabla_{x_2}^2 . \] Here $x_1\in{\bf R}^n$, $x_2\in{\bf R}

J. K. Canci

Let $K$ be a number field and $ϕ\in K(z)$ a rational function. Let $S$ be the set of all archimedean places of $K$ and all non-archimedean places associated to the prime ideals of bad reduction for $ϕ$. We prove an upper bound for length of finite orbits of $ϕ$ in $\mathbb{P}_1(K)$ depending only on the cardinality of $S$.

Ernst Terhardt

The traditional theory of Laplace transformation in its currently prevalent form is unsatisfactory. Its deficiencies can be traced back to a mismatch of the definition intervals of the original function and of the inverse L-transform. A new approach is outlined by which Laplace transformation becomes liberated from its inconsistencies.

S. Sinel&#39;shchikov, A. Stolin, L. Vaksman

We consider Knapp-Vogan Hecke algebras in the quantum group setting. This allows us to produce a quantum analogue of the Bernstein functor as a first step towards the cohomological induction for quantum groups.

Nguyen Tien Zung

We show that proper Lie groupoids are locally linearizable. As a consequence, the orbit space of a proper Lie groupoid is a smooth orbispace (a Hausdorff space which locally looks like the quotient of a vector space by a linear compact Lie group action). In the case of proper (quasi-)symplectic groupoids, the orbit space admits a natural integral affine stru

Emilio Elizalde

Zeta regularization has proven to be a powerful and reliable tool for the regularization of the vacuum energy density in ideal situations. With the Hadamard complement, it has been shown to provide finite (and meaningful) answers too in more involved cases, as when imposing physical boundary conditions (BCs) in two-- and higher--dimensional surfaces (being a

Hirosi Ooguri, Yutaka Ookouchi

We identify configurations of intersecting branes that correspond to the meta-stable supersymmetry breaking vacua in the four-dimensional N=1 supersymmetric Yang-Mills theory coupled to massive flavors. We show how their energies, the stability properties, and the decay processes are described geometrically in terms of the brane configurations.

Stefano De Leo, Pietro Rotelli

We study the solutions for a one-dimensional electrostatic potential in the Dirac equation when the incoming wave packet exhibits the Klein paradox (pair production). With a barrier potential we demonstrate the existence of multiple reflections (and transmissions). The antiparticle solutions which are necessarily localized within the barrier region create ne

Stefano De Leo, Pietro Rotelli

We extend an above barrier analysis made with the Schrodinger equation to the Dirac equation. We demonstrate the perfect agreement between the barrier results and back to back steps. This implies the existence of multiple (indeed infinite) reflected and transmitted wave packets. These packets may be well separated in space or partially overlap. In the latter

Irina Dymnikova

In nonlinear electrodynamics coupled to general relativity and satisfying the weak energy condition, a spherically symmetric electrically charged electrovacuum soliton has obligatory de Sitter center in which the electric field vanishes while the energy density of electromagnetic vacuum achieves its maximal value. De Sitter vacuum supplies a particle with th

Sébastien Ray

As a contribution to the current efforts to understand supersymmetry-breaking by meta-stable vacua, we study general properties of supersymmetry-breaking vacua in Wess-Zumino models: we show that tree-level degeneracy is generic, explore some constraints on the couplings and present a simple model with a long-lived meta-stable vacuum, ending with some genera

C. Meusburger

We define the dual of a set of generators of the fundamental group of an oriented two-surface $S_{g,n}$ of genus $g$ with $n$ punctures and the associated surface $S_{g,n}\setminus D$ with a disc $D$ removed. This dual is another set of generators related to the original generators via an involution and has the properties of a dual graph. In particular, it p

R. D. Peccei

I describe how the QCD vacuum structure, necessary to resolve the $U(1)_A$ problem, predicts the presence of a P, T and CP violating term proportional to the vacuum angle $\barθ$. To agree with experimental bounds, however, this parameter must be very small $(\barθ \leq 10^{-9}$). After briefly discussing some possible other solutions to this, so-called, str

Martin Lavelle, David McMullan

The standard approach to the infra-red problem is to use the Bloch-Nordsieck trick to handle soft divergences and the Lee-Nauenberg (LN) theorem for collinear singularities. We show that this is inconsistent in the presence of massless initial particles. Furthermore, we show that using the LN theorem with such initial states introduces a non-convergent infin

A. Subramanian

It is shown that the absorption of photons at energies > 1 TeV (much higher than the mass of the Higgs boson ~ 100 GeV) is a multi-channel one as opposed to the purely electron pair like absorption at lower energies. The observation on muons and gamma rays from Cygnus X-3 point source at these energies (1 TeV to 10 TeV) is quantitatively accounted for. The e

The BABAR Collaboration, B. Aubert

We present results of a search for the rare flavor-changing neutral-current decay B --> pi l+ l-, based on a data sample corresponding to 209 fb-1 of integrated luminosity collected with the BABAR detector at the PEP-II B Factory. We reconstruct the four exclusive B decay modes B+ --> pi+ l+ l- and B0 --> pi0 l+ l-, where l is either an e or mu. We find no e

Cristinel Diaconu

A search for excited neutrinos produced in electron--proton collisions is performed using a data sample corresponding to an integrated luminosity of 114 pb$^{-1}$ recently collected by the H1 detector at HERA. In absence of a signal, the measurement is interpreted within a minimal model parameterised in terms of couplings and compositness scale. New paramete

B Collaboration

Ratios of the Psi&#39; over the J/psi production cross sections in the dilepton channel for C, Ti and W targets have been measured in 920 GeV proton-nucleus interactions with the HERA-B detector at the HERA storage ring. The Psi&#39; and J/psi states were reconstructed in both the mu+mu- and the e+e- decay modes. The measurements covered the kinematic range

The BABAR Collaboration, B. Aubert

We present the preliminary results from the search of the non-conservation of lepton flavor number in the decay of a $τ$ to a lighter mass lepton and a pseudo-scalar meson, performed using $e^+e^- \to τ^+τ^-$ events collected at a center-of-mass energy near 10.58 GeV with the BABAR detector at the SLAC PEP-II $e^+e^-$ storage ring. No evidence of such a sign

The BABAR Collaboration, B. Aubert

We have searched for the violation of baryon number B and lepton number L in the (B-L)-conserving modes tau- -> anti-Lambda0 pi- and tau- -> anti-Lambda0 K- as well as the (B-L)-violating modes tau- -> Lambda0 pi- and tau- -> Lambda0 K- using 237 inv. fb of data collected with the BABAR detector at the PEP-II asymmetric-energy e+e- storage ring. We do not ob

Z. Y. Turakulov, A. T. Muminov

The studies of influence of spin on a photon&#39;s motion in a Schwartzschild spacetime is continued. In the previous paper [13] the first order correction to the geodesic motion is found for the first half of the photon world line. The system of equations for the first order correction to the geodesic motion is reduced to a non-uniform linear ordinary diffe

Louis Mello

In this paper, we present a method of estimating the volatility of a signal that displays stochastic noise (such as a risky asset traded on an open market) utilizing Linear Predictive Coding. The main purpose is to associate volatility with a series of statistical properties that can lead us, through further investigation, toward a better understanding of st

Wei Zhang, C. A. R. Sa de Melo

There seems to be a one to one correspondence between the phases of atomic and molecular matter (AMOM) and vortex matter (VM) in superfluids and superconductors. Crystals, liquids and glasses have been experimentally observed in both AMOM and VM. However, quasi-crystals also exist in AMOM, thus a new phase of vortex matter is proposed here: the vortex quasi-

Alexandru Macridin, Brian Moritz, Mark Jarrell, Thomas Maier

We study the effect of dynamical Holstein phonons on the physics of the Hubbard model at small doping using the dynamical cluster approximation on a $2\times2$ cluster. Non-local antiferromagnetic correlations are found to significantly enhance the electron-phonon coupling, resulting in polaron formation for moderate coupling strengths. At finite doping, the

N. L. Yoder, N. P. Guisinger, M. C. Hersam, R. Jorn

Electron stimulated desorption of cyclopentene from the Si(100)-2x1 surface is studied experimentally with cryogenic UHV STM and theoretically with transport, electronic structure, and dynamical calculations. Unexpectedly for a saturated hydrocarbon on silicon, desorption is observed at bias magnitudes as low as 2.5 V, albeit the desorption yields are a fact

A. D. Jackson, G. M. Kavoulakis

We consider Bose-Einstein condensed atoms confined in a toroidal trap. We demonstrate that under conditions of one-dimensional behavior, the density distribution of the atoms may be exponentially localized/delocalized, even for very small variations in the trapping potential along the torus. This observation allows one to control the atom density externally

Luca De Sanctis, Marco Isopi

Derrida et al. and Schütz and Stinchcombe gave algebraic formulas for the correlation functions of the partially asymmetric simple exclusion process. Here we give a fairly general recipe of how to get these formulas and extend them to the whole time evolution (starting from the generator of the process), for a certain class of interacting systems. We then an

Luca De Sanctis

We extend the approach of Aizenman, Sims and Starr for the SK-type models to their spherical versions. Such an extension has already been performed for diluted spin glasses. The factorization property of the optimal structures found by Guerra for the SK model, which holds for diluted models as well, is verified also in the case of spherical systems, with the

Markus Mueller, Luca Leuzzi, Andrea Crisanti

We study mean field systems whose free energy landscape is dominated by marginally stable states. We review and develop various techniques to describe such states, elucidating their physical meaning and the interrelation between them. In particular, we give a physical interpretation of the two-group replica symmetry breaking scheme and confirm it by establis

O. Rösch, G. Sangiovanni, O. Gunnarsson

We derive sum rules for the phonon self-energy and the electron-phonon contribution to the electron self-energy of the Holstein-Hubbard model in the limit of large Coulomb interaction U. Their relevance for finite U is investigated using exact diagonalization and dynamical mean-field theory. Based on these sum rules, we study the importance of vertex correct

CM Roland, S Bair, R Casalini

Viscosities and their temperature, T, and volume, V, dependences are reported for 7 molecular liquids and polymers. In combination with literature viscosity data for 5 other liquids, we show that the superpositioning of relaxation times for various glass-forming materials when expressed as a function of TV^g, where the exponent g is a material constant, can

Arnaud Ralko, Michel Ferrero, Federico Becca, Dmitri Ivanov

We report on an exhaustive investigation of the dynamical dimer-dimer correlations in imaginary time for the quantum dimer model on the triangular lattice using the Green&#39;s function Monte Carlo method. We show in particular that soft modes develop upon reducing the dimer-dimer repulsion, indicating the presence of a second-order phase transition into an

Nicolas Garcia, Cheng Hao, Lu Yonghua, Manuel. Munoz

In this paper we show spin dependent transport experiments in nanoconstrictions ranging from 30 to 200nm. These nanoconstrictions were fabricated combining electron beam lithography and thin film deposition techniques. Two types of geometries have been fabricated and investigated. We compare the experimental results with the theoretical estimation of the ele

G. Alvarez, T. C. Schulthess

The calculation of two- and four-particle observables is addressed within the framework of the truncated polynomial expansion method (TPEM). The TPEM replaces the exact diagonalization of the one-electron sector in models for fermions coupled to classical fields such as those used in manganites and diluted magnetic semiconductors. The computational cost of t

F. Kun, M. H. A. S. Costa, R. N. Costa Filho, J. S. Andrade

We present an experimental and theoretical study of the fatigue failure of asphalt under cyclic compression. Varying the load amplitude, experiments reveal a finite fatigue limit below which the specimen does not break, while approaching the tensile strength of the material a rapid failure occurs. In the intermediate load range, the lifetime decreases with t

A. M. Mathai, H. J. Haubold

The pathway model of Mathai (2005) is shown to be inferable from the maximization of a certain generalized entropy measure. This entropy is a variant of the generalized entropy of order &#39;alpha&#39;, considered in Mathai and Rathie (1975), and it is also associated with Shannon, Boltzmann-Gibbs, Renyi, Tsallis, and Havrda-Charvat entropies. The generalize

F. Ianni, R. Di Leonardo, S. Gentilini, G. Ruocco

The aging dynamics after shear rejuvenation in a glassy, charged clay suspension have been investigated through dynamic light scattering (DLS). Two different aging regimes are observed: one is attained if the sample is rejuvenated before its gelation and one after the rejuvenation of the gelled sample. In the first regime, the application of shear fully reju

Lars Rindorf, Niels Asger Mortensen

We present a method for calculating the transmission spectra, dispersion, and time delay characteristics of optical-waveguide gratings based on Green&#39;s functions and Dyson&#39;s equation. Starting from the wave equation for transverse electric modes we show that the method can solve exactly both the problems of coupling of counter-propagating waves (Brag

S. Graser, A. Gumann, T. Dahm, N. Schopohl

As a model for the vortex core in MgB2 we study a two band model with a clean sigma band and a dirty pi band. We present calculations of the vortex core size in both bands as a function of temperature and show that there exists a Kramer-Pesch effect in both bands even though only one of the bands is in the clean limit. We present calculations for different p

V. Arpiainen, M. Lindroos

We derive photoelectron selection rules along the glide plane in orthorhombic Bi_2Sr_2CaCu_2O_{8+δ} (Bi2212). These selection rules explain the reversed intensity behavior of the shadow and the main band of the material as a natural consequence of the variating representation of the final state as a function of k_\parallel. Our one-step simulations strongly

Debjani Banerjee, K. G. Suresh, A. K. Nigam

Structural and magnetization studies were carried out on Dy1-xYxCo5 [x = 0, 0.2, 0.4, 0.6, 0.8, 1] compounds which crystallize in the hexagonal CaCu5-type structure. Lattice parameters and unit-cell volume increase with Y concentration. Large thermomagnetic irreversibility between the field-cooled and the zero-field cooled magnetization data has been observe

H. K. Lee, C. Kwon, Hyunggyu Park

We investigate the equivalence of different operator-splitting schemes for the integration of the Langevin equation. We consider a specific problem, so called the directed percolation process, which can be extended to a wider class of problems. We first give a compact mathematical description of the operator-splitting method and introduce two typical splitti

Hiroshi Kontani, Masanori Ohno

In nearly antiferromagnetic (AF) metals such as high-Tc superconductors (HTSC&#39;s), a single nonmagnetic impurity frequently causes nontrivial widespread change of the electronic states. To elucidate this long-standing issue, we study a Hubbard model with a strong onsite impurity potential based on an improved fluctuation-exchange (FLEX) approximation, whi

Emilio Del Giudice, Giuseppe Vitiello

In the framework of quantum field theory we discuss the emergence of a phase locking among the electromagnetic modes and the matter components on an extended space-time region. We discuss the formation of extended domains exhibiting in their fundamental states non-vanishing order parameters, whose existence is not included in the Lagrangian. Our discussion i

O. Waldmann, C. Dobe, H. U. Güdel, H. Mutka

The inelastic neutron scattering (INS) spectrum is studied for the antiferromagnetic molecular wheel CsFe8, in the temperature range 2 - 60 K, and for transfer energies up 3.6 meV. A qualitative analysis shows that the observed peaks correspond to the transitions between the L-band states, from the ground state up to the S = 5 multiplet. For a quantitative a

J. Yeo, H. Park, S. Yi

We show how a systematic improvement can be made on the nonperturbative parquet approximation method which was previously used to study the effect of thermal fluctuations in vortex liquids in high-temperature superconductors. This is achieved by including an infinite subset of Feynman diagrams contributing to the renormalized four-point vertex function of th

C. J. Hamer, J. Oitmaa, Weihong Zheng, Ross H. McKenzie

We investigate the critical behaviour of the spectral weight of a single quasiparticle, one of the key observables in experiment, for the particular case of the transverse Ising model.Series expansions are calculated for the linear chain and the square and simple cubic lattices. For the chain model, a conjectured exact result is discovered. For the square an

Rudolf Hanel, Stefan Thurner

We generalize the usual exponential Boltzmann factor to any reasonable and potentially observable distribution function, $B(E)$. By defining generalized logarithms $Λ$ as inverses of these distribution functions, we are led to a generalization of the classical Boltzmann-Gibbs entropy, $S_{BG}= -\int d εω(ε) B(ε) \log B(ε)$ to the expression $S\equiv -\int d

T. R. Geballe, F. Najarro, F. Rigaut, J. -R. Roy

Using adaptive optics at the Gemini North telescope we have obtained a K-band spectrum of the star near the center of the luminous Galactic center bowshock IRS8, as well as a spectrum of the bowshock itself. The stellar spectrum contains emission and absorption lines characteristic of an O5-O6 giant or supergiant. The wind from such a star is fully capable o

F. Aharonian

Detailed morphological and spatially resolved spectral studies reveal the very high-energy (VHE) gamma-ray aspects of this object with unprecedented precision. We confirm previous results obtained in a survey of the Galactic Plane in 2004. The gamma-ray emission extends asymmetrically to the south and south-west of the energetic pulsar PSR J1826-1334, that i

Nicolas Leprovost, Eun-Jin Kim

To understand magnetic diffusion, momentum transport, and mixing in the interior of the sun, we consider an idealized model of the tachocline, namely magnetohydrodynamics (MHD) turbulence on a $β$ plane subject to a large scale shear (provided by the latitudinal differential rotation). This model enables us to self-consistently derive the influence of shear,

Akira Mizuta, Tatsuya Yamasaki, Shigehiro Nagataki, Shin Mineshige

We investigate the dynamics of an injected outflow propagating in a progenitor in the context of the collapsar model for gamma-ray bursts (GRBs) through two dimensional axisymmetric relativistic hydrodynamic simulations. Initially, we locally inject an outflow near the center of a progenitor. We calculate 25 models, in total, by fixing its total input energy

Gustavo A. Medina-Tanco

Cosmic ray (CR) particles arrive at the top of the Earth&#39;s atmosphere at a rate of around 1000 per square meter per second. They are mostly ionized nuclei - about 90% protons, 9% alpha particles traces of heavier nuclei and approximately 1% electrons. CRs are characterized by their high energies: most cosmic rays are relativistic, having kinetic energies

Jun-Mein Wu, Keiichi Umetsu, Chia-Hung Chien, Tzihong Chiueh

The technique of weak-lensing aperture mass densitometry, so called the zeta-statistic, has recently been popular in actual observations for measurement of individual cluster mass. It has however been anticipated that the line-of-sight projection by foreground and background matter can adversely affect the cluster mass determination with not only substantial

Joseph L. Hora, William B. Latter, Howard A. Smith, Massimo Marengo

We have mapped the Helix (NGC 7293) planetary nebula (PN) with the IRAC instrument on the Spitzer Space Telescope. The Helix is one of the closest bright PN, and therefore provides an opportunity to resolve the small-scale structure in the nebula. The emission from this PN in the 5.8 and 8 micron IRAC bands is dominated by the pure rotational lines of molecu

Bruce G. Elmegreen, Debra Meloy Elmegreen

The vertical profiles of chain and spiral galaxies in the Hubble Space Telescope Ultra Deep Field (UDF) are fit to sech^2(z/z_0) functions convolved with stellar profiles in order to measure the disk scale heights z_0 in four passbands. The bulge regions of the spirals are avoided. Photometric redshifts give absolute scales. The rms heights of the giant clum