November 2005 arXiv papers — page 40

Jorge Cortes, Manuel de Leon, Juan C. Marrero, D. Martin de Diego

In this survey, we present a geometric description of Lagrangian and Hamiltonian Mechanics on Lie algebroids. The flexibility of the Lie algebroid formalism allows us to analyze systems subject to nonholonomic constraints, mechanical control systems, Discrete Mechanics and extensions to Classical Field Theory within a single framework. Various examples along

Simonetta Abenda, Tamara Grava

We derive the modulation equations or Whitham equations for the Camassa--Holm (CH) equation. We show that the modulation equations are hyperbolic and admit bi-Hamiltonian structure. Furthermore they are connected by a reciprocal transformation to the modulation equations of the first negative flow of the Korteweg de Vries (KdV) equation. The reciprocal trans

Aaron Zerhusen

We show that a pseudoconvex open subset of a Banach space with an unconditional basis is biholomorphic to a closed direct submanifold of a Banach space with an unconditional basis.

Hanne Schultz

Using the spectral subspaces obtained in [HS], Brown's results on the Brown measure of an operator in a type II_1 factor (M,tr) are generalized to finite sets of commuting operators in M. It is shown that whenever T_1,..., T_n in M are mutually commuting operators, there exists one and only one compactly supported Borel probability measure mu_{T_1,..., T

D. A. Goldston, S. M. Gonek

Let $πS(t)$ denote the argument of the Riemann zeta-function at the point $\frac12+it$. Assuming the Riemann Hypothesis, we sharpen the constant in the best currently known bounds for $S(t)$ and for the change of $S(t)$ in intervals. We then deduce estimates for the largest multiplicity of a zero of the zeta-function and for the largest gap between the zeros

Guillaume Bal, Lenya Ryzhik

This paper concerns the derivation of a Fokker-Planck equation for the correlation of two high frequency wave fields propagating in two different random media. The mismatch between the random media need be small, on the order of the wavelength, and their correlation length need be large relative to the wavelength. The loss of correlation caused by the mismat

Aleksandr V. Pukhlikov

We prove birational superrigidity of generic Fano fiber spaces $V/{\mathbb P}^1$, the fibers of which are Fano complete intersections of index 1 and dimension $M$ in ${\mathbb P}^{M+k}$, provided that $M\geq 2k+1$. The proof combines the traditional quadratic techniques of the method of maximal singularities with the linear techniques based on the connectedn

Teodor Oprea

In the theory of minimal submanifold, the following problem is fundamental: when does a given Riemannian manifold admit (or does not admit) a minimal isometric immersion into an Euclidean space form of arbitrary dimension? A partial solution of this problem was obtained by B.Y. Chen as an application of his fundamental inequality [1]. In this paper we obtain

Teodor Oprea

As we showed in [3], a geometric inequality can be regarded as an optimization problem. In this paper we find another proof for a Chen's inequality,regarding the Ricci curvature [2] and we improve this inequality in the Lagrangian case.

Teodor Oprea

In the theory of submanifolds, the following problem is fundamental: to establish simple relationships between the main intrinsic invariants and the main extrinsic invariants of the submanifolds.The basic relationships discovered until now [1, 2, 3, 4] are inequalities. To analyze these problems, we follow the idea of C. Udriste [6, 7, 8] that the method of

Pierre Fima

In this paper we are interested in examples of locally compact quantum groups $(M,Δ)$ such that both von Neumann algebras, $M$ and the dual $\hat{M}$, are factors. There is a lot of known examples such that $(M,\hat{M})$ are respectively of type $(\rm{I}\_{\infty},\rm{I}\_{\infty})$ but there is no examples with factors of other types. We construct new examp

Robert L. Griess

We study the sublattices of the rank $2^d$ Barnes-Wall lattices $\bw d$ which occur as fixed points of involutions. They have ranks $2^{d-1}$ (for dirty involutions) or $2^{d-1}\pm 2^{k-1}$ (for clean involutions), where $k$, the defect, is an integer at most $\frac d 2$. We discuss the involutions on $\bw d$ and determine the isometry groups of the fixed po

Gilbert Levitt

A generalized Baumslag-Solitar group (GBS group) is a finitely generated group $G$ which acts on a tree with all edge and vertex stabilizers infinite cyclic. We show that Out(G) either contains non-abelian free groups or is virtually nilpotent of class at most 2. It has torsion only at finitely many primes. One may decide algorithmically whether Out(G) is vi

S. A. Ladoucette, J. L. Teugels

Let \{X_1, X_2, ...\} be a sequence of independent and identically distributed positive random variables of Pareto-type with index α>0 and let \{N(t); t\geq 0\} be a counting process independent of the X_i's. For any fixed t\geq 0, define T_{N(t)}:=\frac{X_1^2 + X_2^2 + ... + X_{N(t)}^2} {(X_1 + X_2 + ... + X_{N(t)})^2} if N(t)\geq 1 and T_{N(t)}:=0 othe

Juan Carlos Marrero, Diana Sosa

The Hamilton-Jacobi equation for a Hamiltonian section on a Lie affgebroid is introduced and some examples are discussed.

Wolter Groenevelt

We introduce an algebra $\mathcal H$ consisting of difference-reflection operators and multiplication operators that can be considered as a $q=1$ analogue of Sahi's double affine Hecke algebra related to the affine root system of type $(C^\vee_1, C_1)$. We study eigenfunctions of a Dunkl-Cherednik-type operator in the algebra $\mathcal H$, and the corres

Richard C. Bradley

This is an update of, and a supplement to, a 1986 survey paper by the author on basic properties of strong mixing conditions.

G. P. Kapoor, A. K. Mishra

In the present paper, the coefficient estimates are found for the class $\mathcal S^{*-1}(α)$ consisting of inverses of functions in the class of univalent starlike functions of order $α$ in $\mathcal D=\{z\in\mathbb C:|z|<1\}$. These estimates extend the work of {\it Krzyz, Libera and Zlotkiewicz [Ann. Univ. Marie Curie-Sklodowska, 33(1979), 103-109]} who f

Alexander Shapiro, Victor Vinnikov

The work of M. S. Livšic and his collaborators in operator theory associates to a system of commuting nonselfadjoint operators an algebraic curve. Guided by the notion of rational transformation of algebraic curves, we define the notion of a rational transformation of a system of commuting nonselfadjoint operators.

Ernst Joachim Weniger

Asymptotic approximations ($n \to \infty$) to the truncation errors $r_n = - \sum_{ν=0}^{\infty} a_ν$ of infinite series $\sum_{ν=0}^{\infty} a_ν$ for special functions are constructed by solving a system of linear equations. The linear equations follow from an approximative solution of the inhomogeneous difference equation $Δr_n = a_{n+1}$. In the case of t

A. K. B. Chand, G. P. Kapoor

We construct a coalescence hidden variable fractal interpolation function (CHFIF) through a non-diagonal iterated function system(IFS). Such a FIF may be self-affine or non-self-affine depending on the parameters of the defining non-diagonal IFS. The smoothness analysis of the CHFIF has been carried out by using the operator approximation technique. The dete

Terence Tao, Monica Visan, Xiaoyi Zhang

We undertake a comprehensive study of the nonlinear Schrödinger equation $$ i u_t +Δu = λ_1|u|^{p_1} u+ λ_2 |u|^{p_2} u, $$ where $u(t,x)$ is a complex-valued function in spacetime $\R_t\times\R^n_x$, $λ_1$ and $λ_2$ are nonzero real constants, and $0<p_1<p_2\le \frac 4{n-2}$. We address questions related to local and global well-posedness, finite time blowu

Jeffry Phan

A minimal monomial ideal is the combinatorially simplest monomial ideal whose lcm-lattice equals a given finite atomic lattice $\hat{L}$. The minimal ideal inherits many nice properties of any ideal $I$ whose lcm-lattice also equals $\hat{L}$, e.g. Cohen-Macaulayness and the dual property of having a linear resolution. Conversely, any ideal having a linear r

Sophie Ambrose, Max Neunhoeffer, Cheryl E. Praeger, Csaba Schneider

We present a generalisation of the sifting procedure introduced originally by Sims for computation with finite permutation groups, and now used for many computational procedures for groups, such as membership testing and finding group orders. Our procedure is a Monte Carlo algorithm, and is presented and analysed in the context of black-box groups. It is bas

E. Mukhin, A. Varchenko

Jacobi polynomials are polynomials whose zeros form the unique solution of the Bethe Ansatz equation associated with two sl_2 irreducible modules. We study sequences of r polynomials whose zeros form the unique solution of the Bethe Ansatz equation associated with two highest weight sl_{r+1} irreducible modules, with the restriction that the highest weight o

Jeffrey C. Lagarias, Masatoshi Suzuki

This paper studies the non-holomorphic Eisenstein series E(z,s) for the modular surface, and shows that integration with respect to certain non-negative measures gives meromorphic functions of s that have all their zeros on the critical line Re(s) = 1/2. For the constant term of the Eisenstein series it shows that all zeros are on the critical line for fixed

Kiran S. Kedlaya

We prove that for any field k of characteristic p>0, any separated scheme X of finite type over k, and any overconvergent F-isocrystal E over X, the rigid cohomology H^i(X, E) and rigid cohomology with compact supports H^i_c(X,E) are finite dimensional vector spaces. We also establish Poincare duality and the Kunneth formula with coefficients. The arguments

Martin Schaden

The free energy of U(N) and SU(N) gauge theory was recently found to be of order N^0 to all orders of a perturbative expansion about a center-symmetric orbit of vanishing curvature. Here I consider extended models for which this expansion is perturbatively stable. The extreme case of an SU(2) gauge theory whose configuration space is restricted to center-sym

Nicola Caporaso, Michele Cirafici, Luca Griguolo, Sara Pasquetti

We continue our study of the large N phase transition in q-deformed Yang-Mills theory on the sphere and its role in connecting topological strings to black hole entropy. We study in detail the chiral theory defined in terms of uncoupled single U(N) representations at large N and write down the resulting partition function by means of the topological vertex.

Mohammed Kessabi, El Hassan Saidi, Hanane Sebbata

We study an extension of one dimensional Calogero model involving strongly coupled and electrically charged particles. Besides Calogero term $\frac{g}{% 2x^{2}}$, there is an extra factor described by a Yukawa like coupling modeling short distance interactions. Mimicking Calogero analysis and using developments in formal series of the wave function $Ψ(x) $ f

Steven Weinberg

This is the written version of the opening talk at the symposium &#34;Expectations of a Final Theory,&#34; at Trinity College, Cambridge, on September 2, 2005. It is to be published in Universe or Multiverse?, ed. B. Carr (Cambridge University Press).

P. Valtancoli

We study the compatibility between the $BPST SU(2)$ instanton and the fuzzy four-sphere algebra. By using the projective module point of view as an intermediate step, we are able to identify a non-commutative solution of the matrix model equations of motion which minimally extends the SU(2) instanton solution on the classical sphere $S^4$. We also propose to

P. Valtancoli

We show how to generalize our method, based on projective modules and matrix models, which enabled us to derive noncommutative monopoles on a fuzzy sphere, to the non-abelian case, recovering known results in literature. We then discuss a possible candidate for deforming the commutative Chern class to the non-commutative case.

Ctirad Klimcik

We review the notion of (anomalous) Poisson-Lie symmetry of a dynamical system and we outline the Poisson-Lie symmetric deformation of the standard WZW model from the vantage point of the twisted Heisenberg double.

Ruggero Ferrari, Andrea Quadri

The renormalization procedure of the non-linear SU(2) sigma model in D=4 proposed in hep-th/0504023 and hep-th/0506220 is here tested in a truly non-trivial case where the non-linearity of the functional equation is crucial. The simplest example, where the non-linear term contributes, is given by the two-loop amplitude involving the insertion of two ϕ_0 (the

Howard Baer, Tadas Krupovnickas, Azar Mustafayev, Eun-Kyung Park

In supersymmetric models with non-universal gaugino masses, it is possible to have opposite-sign SU(2) and U(1) gaugino mass terms. In these models, the gaugino eigenstates experience little mixing so that the lightest SUSY particle remains either pure bino or pure wino. The neutralino relic density can only be brought into accord with the WMAP measured valu

M. Diehl, M. Gockeler, Ph. Hagler, R. Horsley

Generalized transversity distributions encode essential information on the internal structure of hadrons related to transversely polarized quarks. Lattice QCD allows us to compute the lowest moments of these tensor generalized parton distributions. In this talk, we discuss a first lattice study of the Soffer bound and show preliminary results for transverse

K. Itakura

I discuss recent results on the Color Glass Condensate which is a dense saturated gluonic state and appears as the universal picture of hadrons or nuclei at very high energies.

Pei-Hong Gu

That muon neutrinos $ν_μ$ oscillating into the mixture of tau neutrinos $ν_τ$ and sterile neutrinos $ν_{s}$ has been studied to explain the atmospheric $ν_μ$ disappearance. In this scenario, the effect of Earth matter is a key to determine the fraction of $ν_{s}$. Considering that the Earth matter density has uncertainty and this uncertainty has significant

Daniel Boer

The anomalously large cos(2 phi) asymmetry measured in the Drell-Yan process is discussed. Possible origins of this large deviation from the Lam-Tung relation are considered with emphasis on the comparison of two particular proposals: one that suggests it arises from a QCD vacuum effect and one that suggests it is a hadronic effect. Experimental signatures d

R. Ramanathan, Agam K. Jha, S. S. Singh, K. K. Gupta

Thermal and interfacial properties of a QGP droplet in a hadronic medium are computed using a statistical model of the system. The results indicate a weakly first order transition at a transition temperature \sim (160 \pm 5) MeV. The interfacial surface tension is proportional to the cube of the transition temperaure irrespective of the magnitude of the tran

V. Mateu

We perform a new numerical analysis of hyperon semileptonic decays emphasizing the systematic uncertainties. The poor understanding of SU(3) symmetry breaking effects at second order in the vector form factor translates into a large error of |V(us)|. Using our determination |V(us)| = 0.226 +/- 0.005 together with those coming from other sources we test the u

M. Billo, M. Caselle, M. Hasenbusch, M. Panero

We report the results of a set of high precision simulations performed in the 3d gauge Ising model. We evaluated the interquark potential and the first few energy levels and compared them with the predictions obtained with the effective Nambu-Goto string and with the free bosonic string. The data are precise enough to unambiguously distinguish between the fr

Heather K. Gerberich

Results of searches at the Tevatron for physics (non-SUSY and non-Higgs) beyond the Standard Model using 200/pb to 480/pb of data are discussed. Searches at DO and CDF for Z&#39;, Lepton-Quark compositeness, Randall-Sundrum Gravitons, Large Extra Dimensions, W&#39;, Leptoquarks and Excited Electrons are presented here.

Francesco Forti

Measurements of the angles and sides of the unitarity triangle and of the rates of rare B meson decays are crucial for the precise determination of Standard Model parameters and are sensitive to the presence of new physics particles in the loop diagrams. In this paper the recent measurements performed in this area by Babar and Belle will be presented. The di

Guillelmo Gomez-Ceballos

The Tevatron collider at Fermilab provides a very rich environment for the study Bs mesons. In this paper we will show a few selected topics from the CDF and D0 collaborations, giving special attention to the Bs Mixing analyses. This note corresponds to the proceedings of the Hadron Collider Physics 2005 conference.

Mario Spezziga

We present the latest measurements of the Bc meson properties using 360 pb-1 of data collected by the CDF detector in RUN II. The results include the Bc mass and the ratio of branching fraction Bc->J/psi+l with respect to B->J/psi+K.

Isabell-Alissandra Melzer-Pellmann

The H1 and ZEUS experiments are measuring diffractive interactions in ep collisions at HERA. Performing QCD fits of these data with NLO DGLAP, diffractive parton distribution functions can be calculated. These diffractive PDFs can be used to test QCD factorisation with dijet and charm data.

David Brown

Numerical algorithms based on variational and symplectic integrators exhibit special features that make them promising candidates for application to general relativity and other constrained Hamiltonian systems. This paper lays part of the foundation for such applications. The midpoint rule for Hamilton&#39;s equations is examined from the perspectives of var

G. Dautcourt, M. Abdel-Megied

The structure of a light cone in the Goedel universe is studied. We derive the intrinsic cone metric, calculate the rotation coefficients of the ray congruence forming the cone, determine local differential invariants up to second order, describe the crossover (keel) singularities and give a first discussion of its focal points. Contrary to many rotation coe

Suresh K Maran

An idea of reality conditions in the context of spin foams (Barrett-Crane models) is developed. The square of areas are the most elementary observables in the case of spin foams. This observation implies that simplest reality conditions in the context of the Barrett-Crane models is that the all possible scalar products of the bivectors associated to the tria

Fangyu Li, Zhenya Chen, Ying Yi

It is shown that coupling system between fractal membranes and a Gaussian beam passing through a static magnetic field has strong selection capability for the stochastic relic gravitational wave background. The relic GW components propagating along the positive direction of the symmetrical axis of the Gaussian beam might generate an optimal electromagnetic p

A. V. Kisselev, V. A. Petrov

This paper has been withdrawn by the authors because the authors excluded the paper from electronic proceedings of the conference.

Gus Gutoski

In this thesis we introduce quantum refereed games, which are quantum interactive proof systems with two competing provers. We focus on a restriction of this model that we call &#34;short quantum games&#34; and we prove an upper bound and a lower bound on the expressive power of these games. For the lower bound, we prove that every language having an ordinar

Santo Fortunato, Marian Boguna, Alessandro Flammini, Filippo Menczer

PageRank has become a key element in the success of search engines, allowing to rank the most important hits in the top screen of results. One key aspect that distinguishes PageRank from other prestige measures such as in-degree is its global nature. From the information provider perspective, this makes it difficult or impossible to predict how their pages w

Helmut Seidl, Kumar Neeraj Verma

Cryptographic protocols with single blind copying were defined and modeled by Comon and Cortier using the new class $\mathcal C$ of first order clauses. They showed its satisfiability problem to be in 3-DEXPTIME. We improve this result by showing that satisfiability for this class is NEXPTIME-complete, using new resolution techniques. We show satisfiability

Zengyou He, Xiaofei Xu, Shengchun Deng

Clustering categorical data is an integral part of data mining and has attracted much attention recently. In this paper, we present k-ANMI, a new efficient algorithm for clustering categorical data. The k-ANMI algorithm works in a way that is similar to the popular k-means algorithm, and the goodness of clustering in each step is evaluated using a mutual inf

A. H. Castro Neto, P. Pujol, Eduardo Fradkin

We discuss the problem of proton motion in Hydrogen bond materials with special focus on ice. We show that phenomenological models proposed in the past for the study of ice can be recast in terms of microscopic models in close relationship to the ones used to study the physics of Mott-Hubbard insulators. We discuss the physics of the paramagnetic phase of ic

A. M. Farutin, V. I. Marchenko

The theory of exchange symmetry of spin ordered states is extended to the case of high magnetic field. Low frequency spin dynamics equation for quasi-goldstone mode is derived for two cases of collinear and noncollinear antiferromagnets.

A. Parola, L. Salasnich, R. Rota, L. Reatto

Investigating the quantum phase transition in a ring from a uniform attractive Bose-Einstein condensate to a localized bright soliton we find that the soliton undergoes transverse collapse at a critical interaction strength, which depends on the ring dimensions. In addition, we predict the existence of other soliton configurations with many peaks, showing th

Yuri B. Kudasov

Due to a ferromagnetic in-chain coupling between Co$^{3+}$ ions at trigonal sites, chains Co$_2$O$_6$ are considered as large rigid spin moments. The antiferromagnetic Ising model on the triangular lattice is applied to describe an interchain ordering. An evolution of metastable states in a sweeping magnetic field is investigated by the single-flip technique

G. Kotliar, S. Y. Savrasov, K. Haule, V. S. Oudovenko

We present a review of the basic ideas and techniques of the spectral density functional theory which are currently used in electronic structure calculations of strongly-correlated materials where the one-electron description breaks down. We illustrate the method with several examples where interactions play a dominant role: systems near metal-insulator tran

L. Despont, C. Lichtensteiger, C. Koitzsch, C. Clerc

X-ray photoelectron diffraction is used to directly probe the intra-cell polar atomic distortion and tetragonality associated with ferroelectricity in ultrathin epitaxial PbTiO3 films. Our measurements, combined with ab-initio calculations, unambiguously demonstrate non-centro-symmetry in films a few unit cells thick, imply that films as thin as 3 unit cells

Catherine Gourdon, Vincent Jeudy, Andrejs Cebers

The phase transition between the intermediate and normal states in type-I superconducting films is investigated using magneto-optical imaging. Magnetic hysteresis with different transition fields for collapse and nucleation of superconducting domains is found. This is accompanied by topological hysteresis characterized by the collapse of circular domains and

Ö. Legeza, K. Buchta, J. Sólyom

We have studied the neutral-ionic transition in organic mixed-stack compounds. A unified model has been derived which, in limiting cases, is equivalent to the models proposed earlier, the donor-acceptor model and the ionic Hubbard model. Detailed numerical calculations have been performed on this unified model with the help of the density-matrix renormalizat

K. Buchta, G. Fáth, Ö. Legeza, J. Sólyom

We study numerically the ground-state phase diagram of the bilinear-biquadratic spin-1 chain near the ferromagnetic instability point, where the existence of a gapped or gapless nondimerized quantum nematic phase has been suggested. Our results, obtained by a highly accurate density-matrix renormalization-group (DMRG) calculation are consistent with the view

Sangeeta Sahoo, Takis Kontos, Jürg Furer, Christian Hoffmann

Spintronics is an approach to electronics in which the spin of the electrons is exploited to control the electric resistance R of devices. One basic building block is the spin-valve, which is formed if two ferromagnetic electrodes are separated by a thin tunneling barrier. In such devices, R depends on the orientation of the magnetisation of the electrodes.

I. Sosnin, H. Cho, V. T. Petrashov, A. F. Volkov

We report superconducting phase-periodic conductance oscillations in ferromagnetic wires with interfaces to conventional superconductors. The ferromagnetic wires were made of Ho, a conical ferromagnet. The distance between the interfaces was much larger than the singlet superconducting penetration depth. We explain the observed oscillations as due to the lon

Oren Shafir, Amit Keren, Satoru Maegawa, Miki Ueda

We developed a method to detect the quantum nature of high spin molecules using muon spin rotation, and a three-step field cycle ending always with the same field. We use this method to demonstrate that the Fe8 molecule can remember 6 (possibly 8) different histories (bits). A wide range of fields can be used to write a particular bit, and the information is

L. A. Manakova

In the present paper one-dimensional two-component atomic Fermi gas is considered in long-wave limit as a Luttinger liquid. The mechanisms leading to instability of the non-Fermi-liquid state of a Luttinger liquid with two-level impurities are proposed. Since exchange scattering in 1D systems is two-channel scattering in a certain range of parameters, severa

Jorge Kurchan

This is a brief review of recently derived relations describing the behaviour of systems far from equilibrium. They include the Fluctuation Theorem, Jarzynski&#39;s and Crooks&#39; equalities, and an extended form of the Second Principle for general steady states. They are very general and their proofs are, in most cases, disconcertingly simple.

Cecile Monthus, Thomas Garel

According to recent progress in the finite size scaling theory of critical disordered systems, the nature of the phase transition is reflected in the distribution of pseudo-critical temperatures $T_c(i,L)$ over the ensemble of samples $(i)$ of size $L$. In this paper, we apply this analysis to the delocalization transition of an heteropolymeric chain at a se

Julien Barr&#39;e, Freddy Bouchet, Thierry Dauxois, Stefano Ruffo

We show that the quasi-stationary states observed in the $N$-particle dynamics of the Hamiltonian Mean-Field (HMF) model are nothing but Vlasov stable homogeneous (zero magnetization) states. There is an infinity of Vlasov stable homogeneous states corresponding to different initial momentum distributions. Tsallis $q$-exponentials in momentum, homogeneous in

Hiroaki Matsueda, Takami Tohyama, Sadamichi Maekawa

We examine the single-particle excitation spectrum in the one-dimensional Hubbard-Holstein model at half-filling by performing the dynamical density matrix renormalization group (DDMRG) calculation. The DDMRG results are interpreted as superposition of spectra for a spinless carrier dressed with phonons. The superposition is a consequence of robustness of th

Asish K. Kundu, P. Nordblad, C. N. R. Rao

Magnetic and electric properties of a single crystal of La0.7Ca0.3CoO3 have been experimentally studied. The system attains a ferromagnetic spontaneous moment below 170 K and exhibits a re-entrant spin-glass phase below 100 K. In the ordered and the re-entrant phases, the low field magnetic properties are strongly direction dependent, showing considerably hi

Pi-Gang Luan, Chi-Shung Tang

We consider a charged particle which is driven by a time-dependent flux threading a circular ring system. Various approaches including classical treatment, Fourier expansion method, time-evolution method, and Lewis-Riesenfeld method are used and compared to solve the time-dependent problem. By properly managing the boundary condition of the system, a time-de

Markus J. Henrich, Mathias Michel, Michael Hartmann, Guenther Mahler

We solve the Schroedinger equation for an interacting spin-chain locally coupled to a quantum environment with a specific degeneracy structure. The reduced dynamics of the whole spin-chain as well as of single spins is analyzed. We show, that the total spin-chain relaxes to a thermal equilibrium state independently of the internal interaction strength. In co

Asish K. Kundu, K. Ramesha, Ram Seshadri, C. N. R. Rao

Magnetic and electrical properties of four series of rare earth cobaltates of the formula La0.7-xLnxCa0.3CoO3 with Ln = Pr, Nd, Gd and Dy have been investigated. Compositions close to x = 0.0 contain large ferromagnetic clusters or domains, and show Brillouin-like behaviour of the field-cooled DC magnetization data with fairly high ferromagnetic Tc values, b

Evan Scannapieco, Joseph Silk, Rychard Bouwens

We study the impact of outflows driven by active galactic nuclei (AGN) on galaxy formation. Outflows move into the surrounding intergalactic medium (IGM) and heat it sufficiently to prevent it from condensing onto galaxies. In the dense, high-redshift IGM, such feedback requires highly energetic outflows, driven by a large AGN. However, in the more tenuous l

J. A. Zurita Heras, G. De Cesare, R. Walter, A. Bodaghee

The discovery of the X-ray source IGR J17252-3616 by INTEGRAL was reported on 9 February 2004. Regular monitoring by INTEGRAL shows that IGR J17252-3616 is a persistent hard X-ray source with an average count rate of 0.96 counts/s (~6.4 mCrab) in the 20-60 keV energy band. A follow-up observation with XMM-Newton, which was performed on 21 March 21 2004, show

Denise R. Goncalves, ; Barbara Ercolano, ; A. Carnero, ; A. Mampaso

We have constructed a 3D photoionisation model of a planetary nebula (PN) similar in structure to NGC 7009 with its outer pair of knots (also known as FLIERs --fast, low-ionization emission regions). The work is motivated by the fact that the strong [N II]6583A line emission from FLIERs in many planetary nebulae has been attributed to a significant local ove

G. C. Dewangan, R. E. Griffiths, A. R. Rao

ASCA X-ray spectra of many ULXs were described in terms of optically thick emission from hot (kT ~1-2keV) accretion disks, while recent XMM-Newton and Chandra observations have revealed a cool (kT ~0.2keV), soft X-ray excess emission from a number of them. Here we utilize improved calibration and high signal-to-noise XMM-Newton spectra of NGC1313 X-1 to pres

Denise R. Goncalves

How well do we know the physical/chemical properties of PNe? 1D (CLOUDY) and 3D (MOCASSIN) photoionisation codes are used in this contribution to model the PNe K 4-47 and NGC 7009 as an attempt to question whether or not the high Te (higher than 21,000K) of the K 4-47&#39;s core and the N overabundance of the outer knots in NGC 7009 are real. These are very

Kisha M. Delain, Lawrence Rudnick

We have discovered new diffuse radio sources likely associated with groups of galaxies at low redshift (0.01-0.04) and without apparent AGN by using the WENSS and WISH catalogs to perform an unbiased survey. These sources resemble the radio halos, mini-halos, and &#39;relics&#39; of rich clusters, which are thought to be powered by shocks and turbulence from

Denise R. Goncalves

Planetary nebulae (PNe) are known to possess a variety of small-scale structures that are usually in a lower ionization state than the main body of the nebulae. The morphological and kinematic properties of these low-ionization structures (LISs) vary from type to type in the sense that LISs can appear in the form of pairs of knots, filaments, jets, and isola

G. Chincarini

In the introduction we give the main characteristics of the Swift mission outlining how the design was driven by the science goals and by the heritage we got from the Italian - Dutch satellite Beppo SAX. We show some of the new characteristics of the X - ray light curves that became evident soon after we obtained the first set of data. In addition to the ear

G. Chincarini, V. Mangano, A. Moretti, M. Perri

Following a brief introduction we show that the observations obtained so far with the Swift satellite begin to shed light over a variety of problems that were left open following the excellent performance and related discoveries of the Italian - Dutch Beppo SAX satellite. The XRT light curves show common characteristics that are reasonably understood within

Raka Dona Ray Mandal, Monika Sinha, Manjari Bagchi, Sushan Konar

It appears that there is a genuine shortage of radio pulsars with surface magnetic fields significantly smaller than $\sim 10^8$ Gauss. We propose that the pulsars with very low magnetic fields are actually strange stars locked in a state of minimum free energy and therefore at a limiting value of the magnetic field which can not be lowered by the system spo

A. Kashlinsky, R. G. Arendt, J. Mather, S. H. Moseley

The deepest space and ground-based observations find metal-enriched galaxies at cosmic times when the Universe was <1 Gyr old. These stellar populations had to be preceded by the metal-free first stars, Population III. Recent cosmic microwave background polarization measurements indicate that stars started forming early when the Universe was $\lsim200$ Myr o

D. Allard, I. Allekotte, E. Armengaud, J. Aublin

We determine the instantaneous aperture and integrated exposure of the surface detector of the Pierre Auger Observatory, taking into account the trigger efficiency as a function of the energy, arrival direction (with zenith angle lower than 60 degrees) and nature of the primary cosmic-ray. We make use of the so-called Lateral Trigger Probability function (or

G. Migliori, P. Grandi, G. G. C. Palumbo, G. Brunetti

X-ray emission from the eastern radio lobe of the FRII Radio Galaxy Pictor A was serendipitously discovered by a short observation of XMM-Newton in 2001. The X-ray spectrum, accumulated on a region covering about half of the entire radio lobe, was well described by both a thermal model and a power law, making non-univocal the physical interpretation. A new X

S. Fischer, C. Iserlohe, J. Zuther, T. Bertram

We created a sample of nearby QSOs selected from the Hamburg/ESO survey and the Veron-Cetty & Veron catalog, with a limiting redshift of z<0.06, which consists of 63 objects. In this contribution, we present the results of our ISAAC Ks-band spectroscopic and H and Ks-band photometric observations of 9 sources of this sample. In seven sources we find hydrogen

Thomas J. Maccarone, Arunav Kundu, Stephen E. Zepf, Anthony L. Piro

We report the results of a deep Chandra survey of the Sculptor dwarf spheroidal galaxy. We find five X-ray sources with L_X of at least 6*10^33 ergs/sec with optical counterparts establishing them as members of Sculptor. These X-ray luminosities indicate that these sources are X-ray binaries, as no other known class of Galactic point sources can reach 0.5-8

B. T. Gaensicke, K. S. Long, M. A. Barstow, I. Hubeny

We have obtained FUSE and HST/STIS time-resolved spectroscopy of the polar AM Herculis during a deep low state. The spectra are entirely dominated by the emission of the white dwarf. Both the far-ultraviolet (FUV) flux as well as the spectral shape vary substantially over the orbital period, with maximum flux occurring at the same phase as during the high st

M. Gillon, P. Magain

One of the main goals of the COROT mission is to get precise photometric observations of selected bright stars in order to allow the modelling of their interior through asteroseismology. However, in order to interpret the asteroseismological data, the effective temperature, surface gravity, and chemical composition of the stars must be known with sufficient

O. C. de Jager, C. Venter

The excellent sensitivity and high resolution capability of wide FoV ground-based imaging atmospheric Cerenkov telescopes allow us for the first time to resolve the morphological structures of pulsar wind nebulae (PWN) which are older and more extended than the Crab Nebula. VHE gamma-ray observations of such extended nebulae (with field strengths below ~ 20

G. Tagliaferri, S. Campana, G. Chincarini, P. Giommi

The X-ray Telescope (XRT), on board the {\it Swift} satellite, provides: automated source detection and position with few arcsecond accuracy within few seconds from target acquisition; CCD spectroscopy and imaging capability (0.2-10 keV), with the capability of detecting a milliCrab source in about 10 seconds; automatic adjusting of the CCD readout mode to o

D. Stamatellos, A. P. Whitworth, S. P. Goodwin

Class 0 objects, which are thought to be the youngest protostars, are identified in terms of NIR or radio emission and/or the presence of molecular outflows. We present combined hydrodynamic and radiative transfer simulations of the collapse of a star-forming molecular core, which suggest two criteria for identifying dense cores with deeply embedded very you

Brad M. S. Hansen, Shri Kulkarni, Sloane Wiktorowicz

We examine 14 hot white dwarfs for signs of infrared excess using the Spitzer Space Telescope. Twelve of the objects are massive white dwarfs which have been suggested to be the result of binary mergers. The remaining two objects are undermassive white dwarfs which again may be the result of mergers or the inspiral of a substellar companion. In no case do we

J. Kiener, M. Gros, V. Tatischeff, G. Weidenspointner

Analysis of spectra obtained with the gamma-ray spectrometer SPI onboard INTEGRAL of the GOES X17-class flare on October 28, 2003 is presented. In the energy range 600 keV - 8 MeV three prominent narrow lines at 2.223, 4.4 and 6.1 MeV, resulting from nuclear interactions of accelerated ions within the solar atmosphere could be observed. Time profiles of the