January 2007 arXiv papers — page 13

Haidong Liu

We present the transverse momentum spectra at mid-rapidity for $d$, $\bar{d}$ ($1<p_{T}<4 GeV/c$) and $^{3}He$, $\bar{^{3}He}$ ($2<p_{T}<6 GeV/c$) measured by the STAR experiment at RHIC and extract the coalescence parameters $B_{2}$ and $B_{3}$ (respectively). We also present the $v_{2}$ measurement for $d(\bar{d})$ and $^{3}He(\bar{^{3}He})$. We find that

Bedangadas Mohanty

We present the incident energy and system size dependence of the pT spectra for charged pions, protons, and anti-protons using Au+Au and Cu+Cu collisions at Sqrt(sNN) = 62.4 and 200 GeV in STAR experiment at RHIC. Through these measurements in the pT range of 0.2 < pT < 10 GeV/c we conduct a systematic study of the beam energy, system size and particle speci

Wei Li

We present results on two-particle angular correlations in p+p and Cu+Cu collisions over a broad range of ($η$,$ϕ$). The PHOBOS detector has a uniquely large angular coverage for inclusive charged particles. This allows for the study of correlations on both long and short range pseudorapidity scales. A complex two-dimensional correlation structure emerges wh

Rachid Nouicer

We present a systematic study of elliptic flow as a function of centrality, pseudorapidity, transverse momentum and energy for Cu+Cu and Au+Au collisions from the PHOBOS experiment. New data on elliptic flow in Cu+Cu collisions at 22.4 GeV are shown. Elliptic flow scaled by participant eccentricity is found to be similar for both systems when collisions with

D. G. Middleton, J. R. M. Annand, C. Barbieri, P. Barneo

This paper reports on the first measurement of the ^16O(e,e&#39;pn)^14N reaction. Data were measured in kinematics centred on a super-parallel geometry at energy and momentum transfers of 215 MeV and 316 MeV/c. The experimental resolution was sufficient to distinguish groups of states in the residual nucleus but not good enough to separate individual states.

Sarah-Louise Blyth

We present the centrality dependence of the $N(Ω)/N(ϕ)$ ratios and $ϕ$ $v_{2}$ measured in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV by the STAR experiment at RHIC. The results are compared to measurements of other identified particles and recombination model expectations in order to gain insight into the partonic collectivity and possible thermalization o

D. J. Hofman

This manuscript contains a summary of the latest physics results from PHOBOS, as reported at Quark Matter 2006. Highlights include the first measurement from PHOBOS of dynamical elliptic flow fluctuations as well as an explanation of their possible origin, two-particle correlations, identified particle ratios, identified particle spectra and the latest resul

Austin Gerig, Alfred Hubler

We study the dynamics of a one-dimensional discrete flow with open boundaries - a series of moving point particles connected by ideal springs. These particles flow towards an inlet at constant velocity, pass into a region where they are free to move according to their nearest neighbor interactions, and then pass an outlet where they travel with a sinusoidall

Robert Conte

The dependence of the sixth equation of Painleve&#39; on its four parameters $(2 α,-2 β,2 γ,1-2 δ) =(θ_{\infty}^2,θ_{0}^2,θ_{1}^2,θ_{x}^2)$ is holomorphic, therefore one expects all its Lax pairs to display such a dependence. This is indeed the case of the second order scalar ``Lax&#39;&#39; pair of Fuchs, but the second order matrix Lax pair of Jimbo and Mi

Kenneth W. Johnson, Petr Vojtěchovský

The variety of quasigroups satisfying the identity $(xy)(zy)=xz$ mirrors the variety of groups, and offers a new look at groups and their multiplication tables. Such quasigroups are constructed from a group using right division instead of multiplication. Their multiplication tables consist of circulant blocks which have additional symmetries and have a conci

J. D. Phillips, Petr Vojtěchovský

A quasigroup identity is of Bol-Moufang type if two of its three variables occur once on each side, the third variable occurs twice on each side, the order in which the variables appear on both sides is the same, and the only binary operation used is the multiplication, viz. $((xy)x)z=x(y(xz))$. Many well-known varieties of quasigroups are of Bol-Moufang typ

J. D. Phillips, Petr Vojtěchovský

A loop identity is of Bol-Moufang type if two of its three variables occur once on each side, the third variable occurs twice on each side, and the order in which the variables appear on both sides is the same, viz. $((xy)x)z=x(y(xz))$. Loop varieties defined by one identity of Bol-Moufang type include groups, Bol loops, Moufang loops and C-loops. We show th

J. D. Phillips, Petr Vojtěchovský

A groupoid identity is said to be linear of length $2k$ if the same $k$ variables appear on both sides of the identity exactly once. We classify and count all varieties of groupoids defined by a single linear identity. For $k=3$, there are 14 nontrivial varieties and they are in the most general position with respect to inclusion. Hentzel et. al. showed that

Petr Vojtěchovský

We show how to obtain all nonassociative Moufang loops of order less than 64 and 4262 nonassociative Moufang loops of order 64 in a unified way. We conjecture that there are no other nonassociative Moufang loops of order 64. The main idea of the computer search is to modify precisely one quarter of the multiplication table in a certain way, previously applie

J. D. Phillips, Petr Vojtěchovský

C-loops are loops satisfying $x(y(yz))=((xy)y)z$. They often behave analogously to Moufang loops and they are closely related to Steiner triple systems and combinatorics. We initiate the study of C-loops by proving: (i) Steiner loops are C-loops, (ii) C-loops are alternative, inverse property loops with squares in the nucleus, (iii) the nucleus of a C-loop i

Aleš Drápal, Petr Vojtěchovský

Two constructions due to Drápal produce a group by modifying exactly one quarter of the Cayley table of another group. We present these constructions in a compact way, and generalize them to Moufang loops, using loop extensions. Both constructions preserve associators, the associator subloop, and the nucleus. We conjecture that two Moufang 2-loops of finite

Petr Vojtěchovský

Let $G$ be a finite group and $C_2$ the cyclic group of order 2. Consider the 8 multiplicative operations $(x,y)\mapsto (x^iy^j)^k$, where $i$, $j$, $k\in\{-1, 1\}$. Define a new multiplication on $G\times C_2$ by assigning one of the above 8 multiplications to each quarter $(G\times\{i\})\times(G\times\{j\})$, for $i$, $j\in C_2$. We describe all situations

Petr Vojtěchovský

We first find the combinatorial degree of any map $f:V\to F$ where $F$ is a finite field and $V$ is a finite-dimensional vector space over $F$. We then simplify and generalize a certain construction due to Chein and Goodaire that was used in characterizing code loops as finite Moufang loops that posses at most two squares. The construction yields binary code

Gábor P. Nagy, Petr Vojtěchovský

Nonassociative finite simple Moufang loops are exactly the loops constructed by Paige from Zorn vector matrix algebras. We prove this result anew, using geometric loop theory. In order to make the paper accessible to a broader audience, we carefully discuss the connections between composition algebras, simple Moufang loops, simple Moufang 3-nets, $S$-simple

Petr Vojtěchovský

We derive presentations for Moufang loops of type $M(G,2)$, defined by Chein, with $G$ finite, two-generated. We then use $G=S_3$ to visualize the smallest non-associative Moufang loop.

Petr Vojtěchovský

Let $G$ be a finite group and $C_2$ the cyclic group of order 2. Consider the 8 multiplicative operations $(x,y)\mapsto (x^iy^j)^k$, where $i$, $j$, $k\in\{-1, 1\}$. Define a new multiplication on $G\times C_2$ by assigning one of the above 8 multiplications to each quarter $(G\times\{i\})\times(G\times\{j\})$, for $i$, $j\in C_2$. When $G$ is nonabelian the

Petr Vojtěchovský

Hasse constants and their basic properties are introduced to facilitate the connection between the lattice of subalgebras of an algebra $C$ and the natural action of the automorphism group $Aut(C)$ on $C$. These constants are then used to describe the lattice of subloops of the smallest nonassociative simple Moufang loop.

Petr Vojtěchovský

The probability that $m$ randomly chosen elements of a finite power associative loop $C$ have prescribed orders and generate $C$ is calculated in terms of certain constants related to the action of $Aut(C)$ on the subloop lattice of $C$. As an illustration, all meaningful probabilities of random generation by elements of given orders are found for the smalle

Petr Vojtěchovský

Moufang loops are one of the best-known generalizations of groups. There is only one countable family of nonassociative finite simple Moufang loops, arising from the split octonion algebras. We prove that every member of this family is generated by three elements, using the classical results on generators of unimodular groups.

Gábor P. Nagy, Petr Vojtěchovský

Let $F$ be a perfect field and $M^*(F)$ the nonassociative simple Moufang loop consisting of the units in the (unique) split octonion algebra $O(F)$ modulo the center. Then $Aut(M^*(F))$ is equal to $G_2(F) \rtimes Aut(F)$. In particular, every automorphism of $M^*(F)$ is induced by a semilinear automorphism of $O(F)$. The proof combines results and methods

Petr Vojtěchovský

Let $M^*(q)$ be the unique nonassociative finite simple Moufang loop constructed over $GF(q)$. We prove that $Aut(M^*(2))$ is the Chevalley group $G_2(2)$, by extending multiplicative automorphism of $M^*(2)$ into linear automorphisms of the unique split octonion algebra over GF(2). Many of our auxiliary results apply in the general case. In the course of th

Petr Vojtěchovský

For $n>3$, every $n\times n$ partial Cayley matrix with at most $n-1$ holes can be reconstructed by quadrangle criterion. Moreover, the holes can be filled in given order. Without additional assumptions, this is the best possible result. Reconstruction of other types of multiplication tables is discussed.

Haakan Hedenmalm

We study the Beurling and Fourier transforms on subspaces of $L^2({\mathbb C})$ defined by an invariance property with respect to the root-of-unity group. This leads to generalizations of these transformations acting unitarily on weighted $L^2$-spaces over $\mathbb C$.

Petr Vojtěchovský

For most (and possibly all) non-associative finite simple Moufang loops, three generators of order 3 can be chosen so that each two of them generate a group isomorphic to $(3, 3 | 3, p)$. The subgroup structure of $(3, 3 | 3, p)$ depends on the solvability of a certain quadratic congruence, and it is described here in terms of generators.

Partha Sarathi Chakraborty, Arupkumar Pal

The quantum group $SU_q(\ell+1)$ has a canonical action on the odd dimensional sphere $S_q^{2\ell+1}$. All odd spectral triples acting on the $L_2$ space of $S_q^{2\ell+1}$ and equivariant under this action have been characterized. This characterization then leads to the construction of an optimum family of equivariant spectral triples having nontrivial $K$-

Petr Vojtěchovský

We present an elementary proof that the nonassociative simple Moufang loops over finite prime fields are generated by three elements. In the last section, we conclude that integral Cayley numbers of unit norm are generated multiplicatively by three elements.

Petr Vojtěchovský

The existence and uniqueness (up to equivalence) of code loops was first established by R. Griess. Nevertheless, the explicit construction of code loops remained open until T. Hsu introduced the notion of symplectic cubic spaces and their Frattini extensions, and pointed out how the construction of code loops followed from the (purely combinatorial) result o

Eric Jespers, David Riley, Salvatore Siciliano

An algebra is called a GI-algebra if its group of units satisfies a group identity. We provide positive support for the following two open problems. 1. Does every algebraic GI-algebra satisfy a polynomial identity? 2. Is every algebraically generated GI-algebra locally finite?

Yu Zhang

We consider the first passage percolation model on the square lattice. In this model, $\{t(e): e{an edge of}{\bf Z}^2 \}$ is an independent identically distributed family with a common distribution $F$. We denote by $T({\bf 0}, v)$ the passage time from the origin to $v$ for $v\in {\bf R}^2$ and $B(t)=\{v\in {\bf R}^d: T({\bf 0}, v)\leq t\}.$ It is well know

Benjin Xuan, Jiangchao Wang

In this paper, we study the asymptotic behavior of radial extremal functions to an inequality involving Hardy potential and critical Sobolev exponent. Based on the asymptotic behavior at the origin and the infinity, we shall deduce a strict inequality between two best constants. Finally, as an application of this strict inequality, we consider the existence

Borys Alvarez-Samaniego, David Lannes

We study the well-posedness of the initial value problem for a wide class of singular evolution equations. We prove a general well-posedness theorem under three assumptions easy to check: the first controls the singular part of the equation, the second the behavior of the nonlinearities, and the third one assumes that an energy estimate can be found for the

José Bertin, Matthieu Romagny

We give a thorough study of Hurwitz stacks both in Galois and non galois case. The construction is applied to revisit somme classical examples, the stack of stable curves equipped with a level structure, and the stacks of tamely ramified cyclic covers. We exhibit some tautological cohomology classes, and give some universal relations between them. Applicatio

Vladimir V. Mangazeev

In this letter I shall review my joint results with Vadim Kuznetsov and Evgeny Sklyanin [Indag. Math. 14 (2003), 451-482, math.CA/0306242] on separation of variables for the $A_n$ Jack polynomials. This approach originated from the work [RIMS Kokyuroku 919 (1995), 27-34, solv-int/9508002] where the integral representations for the $A_2$ Jack polynomials was

Nguyen Tu Cuong, Nguyen Thi Dung, Le Thanh Nhan

Let $(R,\m)$ be a Noetherian local ring and $M$ a finitely generated $R-$module with $\dim M=d.$ This paper is concerned with the following property for the top local cohomology module $H^d_\m(M)$: $$\Ann (0:_{H^d_\m(M)}\p)=\p\ \text{for all prime ideals} \p\supseteq\Ann H^d_\m(M).$$ In this paper we will show that this property is equivalent to the catenari

Tanja Bergkvist, Jan-Erik Bjork

In this paper we partially settle our conjecture from [1] (math.SP/0701143) on roots of eigenpolynomials for degenerate exactly-solvable operators. Namely, for any such operator, we establish a lower bound (which supports our conjecture) for the largest modulus of the roots of its unique and monic eigenpolynomial as its degree tends to infinity. The main the

Jingzhong Zhang, Yong Feng

Numerical approximate computation can solve large and complex problems fast. It has the advantage of high efficiency. However it only gives approximate results, whereas we need exact results in many fields. There is a gap between approximate computation and exact results. A bridge overriding the gap was built by Zhang, in which an exact rational number is re

Jingzhong Zhang, Yong Feng

Factorization of polynomials arises in numerous areas in symbolic computation. It is an important capability in many symbolic and algebraic computation. There are two type of factorization of polynomials. One is convention polynomial factorization, and the other approximate polynomial factorization. Conventional factorization algorithms use symbolic methods

Debraj Chakrabarti

We study the approximation of maps into complex manifolds along with interpolation on certain compact subsets of the plane. Results are also obtained regarding approximation and interpolation of sections of holomorphic submersions.

Caterina Cumino, Eduardo Esteves, Letterio Gatto

Let C be the union of two general connected, smooth, nonrational curves X and Y intersecting transversally at a point P. Assume that P is a general point of X or of Y. Our main result, in a simplified way, says: Let Q be a point of X. Then Q is the limit of special Weierstrass points on a family of smooth curves degenerating to C if and only if Q is not P an

Caterina Cumino, Eduardo Esteves, Letterio Gatto

Let C be a general connected, smooth, projective curve of positive genus g. For each nonnegative integer i we give formulas for the number of pairs (P,Q) em C x C off the diagonal such that (g+i-1)Q-(i+1)P is linearly equivalent to an effective divisor, and the number of pairs (P,Q) em C x C off the diagonal such that (g+i+1)Q-(i+1)P is linearly equivalent t

Krishna Athreya, Siva Athreya, Srikanth Iyer

This paper studies: (i) the long time behaviour of the empirical distribution of age and normalised position of an age dependent critical branching Markov process conditioned on non-extinction; and (ii) the super-process limit of a sequence of age dependent critical branching Brownian motions.

H. Belich, T. Costa-Soares, J. A. Helayel-Neto, M. T. D. Orlando

We show in this paper that the dynamics of a non-relativistic particle with spin, coupled to an external electromagnetic field and to a background that breaks Lorentz symmetry, is naturally endowed with an N=1-supersymmetry. This result is achieved in a superspace approach where the particle coordinates and the spin degrees of freedom are components of the s

Matteo Beccaria

We study the supersymmetric vacua of the Veneziano-Wosiek model in sectors with fermion number F=2, 4 at finite &#39;t Hooft coupling lambda. We prove that for F=2 there are two zero energy vacua for lambda > lambda_c = 1 and none otherwise. We give the analytical expressions of both vacua. One of them was previously known, the second one is obtained by solv

N. Riazi, A. Sheykhi

We study the stepwise sine-Gordon equation, in which the system parameter is different for positive and negative values of the scalar field. By applying appropriate boundary conditions, we derive relations between the soliton velocities before and after collisions. We investigate the possibility of formation of heavy soliton pairs from light ones and vise ve

Bernard de Wit, Frank Saueressig

We review the relation between 4n-dimensional quaternion-Kahler metrics with n+1 abelian isometries and superconformal theories of n+1 tensor supermultiplets. As an application we construct the class of eight-dimensional quaternion-Kahler metrics with three abelian isometries in terms of a single function obeying a set of linear second-order partial differen

Frithjof Karsch

We present results from a calculation of the transition temperature in QCD with two light and one heavier (strange) quark mass on lattices with temporal extent N_t =4 and 6. Calculations with improved staggered fermions have been performed with a strange quark mass fixed close to its physical value and for various light to strange quark mass ratios that corr

Francois Arleo

Photon-tagged correlations may be useful to determine how the dense partonic medium produced in heavy-ion collisions affects the fragmentation of high-energy quarks and gluons into a leading hadron. In these proceedings, I discuss the kinematic requirements for the hadron and the prompt photon transverse momentum cuts. A case study at LHC energy, tagging on

Paolo Castorina, Massimo Mannarelli

The Equation of State and the properties of matter in the high temperature deconfined phase are analyzed by a quasiparticle approach for $T> 1.2~T_c$. In order to fix the parameters of our model we employ the lattice QCD data of energy density and pressure. First we consider the pure SU(3) gluon plasma and it turns out that such a system can be described in

UTfit Collaboration, M. Bona, M. Ciuchini, E. Franco

Motivated by a recent paper that compares the results of the analysis of the CKM angle alpha in the frequentist and in the Bayesian approaches, we have reconsidered the information on the hadronic amplitudes, which helps constraining the value of alpha in the Standard Model. We find that the Bayesian method gives consistent results irrespective of the parame

Oliviero Cremonesi, Alessandro Melchiorri

Low energy neutrino processes are ideal probes for new Physics beyond the Standard Model. Cosmological observations and rare nuclear processes can test neutrino mass scales and give definite answers to unsolved basic questions like the Majorana/Dirac nature of the neutrino.

Owen Pavel Fernandez Piedra, Alejandro Cabo Montes de Oca

The renormalized mean value of the quantum Lagrangian and the Energy-Momentum tensor for scalar fields coupled to an arbitrary gravitational field configuration are analytically evaluated in the Schwinger-DeWitt approximation, up to second order in the inverse mass value. The cylindrical symmetry situation is considered. The results furnish the starting poin

L. Matone, P. Raffai, S. Marka, R. Grossman

We present an approach to experimentally evaluate gravity gradient noise, a potentially limiting noise source in advanced interferometric gravitational wave (GW) detectors. In addition, the method can be used to provide sub-percent calibration in phase and amplitude of modern interferometric GW detectors. Knowledge of calibration to such certainties shall en

Luc Brun, Walter G. Kropatsch

Irregular pyramids are made of a stack of successively reduced graphs embedded in the plane. Such pyramids are used within the segmentation framework to encode a hierarchy of partitions. The different graph models used within the irregular pyramid framework encode different types of relationships between regions. This paper compares different graph models us

Wim Vanhoof, Susana Munoz-Hernandez

This volume contains the papers presented at WLPE&#39;06: the 16th Workshop on Logic-based Methods in Programming Environments held on August 16, 2006 in the Seattle Sheraton Hotel and Towers, Seattle, Washington (USA). It was organised as a satellite workshop of ICLP&#39;06, the 22th International Conference on Logic Programming.

Michael Hanus

We present CurryBrowser, a generic analysis environment for the declarative multi-paradigm language Curry. CurryBrowser supports browsing through the program code of an application written in Curry, i.e., the main module and all directly or indirectly imported modules. Each module can be shown in different formats (e.g., source code, interface, intermediate

Scott T. Knauert, Jack F. Douglas, Francis W. Starr

Nanoparticles can influence the properties of polymer materials by a variety of mechanisms. With fullerene, carbon nanotube, and clay or graphene sheet nanocomposites in mind, we investigate how particle shape influences the melt shear viscosity $η$ and the tensile strength $τ$, which we determine via molecular dynamics simulations. Our simulations of compac

Robert M. Konik, Yury Adamov

We present a renormalization group (RG) procedure which works naturally on a wide class of interacting one-dimension models based on perturbed (possibly strongly) continuum conformal and integrable models. This procedure integrates Kenneth Wilson&#39;s numerical renormalization group with Al. B. Zamolodchikov&#39;s truncated conformal spectrum approach. Key

A. Riminucci, I. Bergenti, L. E. Hueso, M. Murgia

We report detailed investigations of hybrid organic-inorganic vertical spin valves. Spin polarized injection in tris(8-hydroxyquinoline) aluminum (Alq3) organic semiconductor (OS) was performed using La0.7Sr0.3MnO3 manganite as the bottom electrode and Co as the top electrode. While manganite was directly connected to the organic semiconductor layer, a thin

Mariana Rossi, Adalberto Fazzio, Antonio J. R. da Silva

We have made a systematic theoretical study to determine which are the most stable structures for substitutional nitrogen defects in carbon nanotubes, by making total energy calculations via DFT. These calculations were made for a (5,5) and a (8,0) nanotube to check the influence of chirality and for a graphene sheet, to check the limit of infinite diameter.

Thimo Rohlf, Natali Gulbahce, Christof Teuscher

We systematically study and compare damage spreading at the sparse percolation (SP) limit for random boolean and threshold networks with perturbations that are independent of the network size $N$. This limit is relevant to information and damage propagation in many technological and natural networks. Using finite size scaling, we identify a new characteristi

Zhihong Chen, Yu-Ming Lin, Michael J. Rooks, Phaedon Avouris

We have fabricated graphene nano-ribbon field-effect transistor devices and investigated their electrical properties as a function of ribbon width. Our experiments show that the resistivity of a ribbon increases as its width decreases, indicating the impact of edge states. Analysis of temperature dependent measurements suggests a finite quantum confinement g

S. Burdin, P. Fulde

The interplay between the Kondo effect and disorder is studied. This is done by applying a matrix coherent potential approximation (CPA) and treating the Kondo interaction on a mean-field level. The resulting equations are shown to agree with those derived by the dynamical mean-field method (DMFT). By applying the formalism to a Bethe tree structure with inf

Prasenjit Ghosh, Shobhana Narasimhan, Stephen J. Jenkins, David A. King

The adsorption of CO on unreconstructed and reconstructed Ir{100} has been studied, using a combination of density functional theory and thermodynamics, to determine the relative stability of the two phases as a function of CO coverage, temperature and pressure. We obtain good agreement with experimentaldata. At zero temperature, the (1X5) reconstruction bec

M. Fehr, D. Andronikov, V. Kochereshko, S. A. Crooker

We study the temperature-dependent modifications of trion and exciton photoluminescence (PL) spectra in modulation-doped CdTe/CdMgTe quantum wells in high magnetic field. We find that, in magnetic field, the temperature-dependent redistribution of exciton and trion PL intensities is opposite to that expected from a simple Boltzmann distribution model. Solvin

W. Nelson, P. Bokes, Patrick Rinke, R. W. Godby

Atomic hydrogen provides a unique test case for computational electronic structure methods, since its electronic excitation energies are known analytically. With only one electron, hydrogen contains no electronic correlation and is therefore particularly susceptible to spurious self-interaction errors introduced by certain computational methods. In this pape

A. R. Pereira, E. Ercolessi, A. S. T. Pires

In this letter we extend the nonlinear sigma model describing pure spin ladders with an arbitrary number of legs to the case of ladders containing a single static hole. A simple immediate application of this approach to classical ladders is worked out.

E. Orignac, R. Citro, T. Giamarchi

We analyze the spin relaxation time $1/T_1$ for a system made of weakly coupled one dimensional ladders.This system allows to probe the dimensional crossover between a Luttinger liquid and a Bose-Einstein condensateof magnons. We obtain the temperature dependence of $1/T_1$ in the various dimensional regimes, and discuss the experimental consequences.

A. M. Panich, M. Shao, C. L. Teske, W. Bensch

We report on size-dependent properties of dithallium selenide, Tl2Se. We have carried out a comparative nuclear magnetic resonance (NMR) study of Tl2Se nanorods and bulk samples, measuring NMR spectra and spin-lattice relaxation rate of 203Tl and 205Tl isotopes. Though bulk Tl2Se was reported to be a metal, the Korringa-like spin-lattice relaxation behavior

Mukul S. Laad, Luis Craco

We introduce a Cellular Dynamical Cluster Approximation (CDCA) to study the nature of the Mott insulator-metal transition in the extended Hubbard model on a square lattice. At strong coupling, a d-wave Mott insulator is obtained. Hole doping drives a first order Mott transition to a non-Fermi (nFL) liquid metal. Remarkably, this nFL is caused by an Anderson

H Chamati, S Romano

We have considered two classical lattice-gas models, consisting of particles that carry multicomponent magnetic momenta, and associated with a two-dimensional square lattices; each site can host one particle at most, thus implicitly allowing for hard-core repulsion; the pair interaction, restricted to nearest neighbors, is ferromagnetic and involves only two

P. Lemmens, P. Scheib, Y. Krockenberger, L. Alff

The effect of surface degradation of the thermolectric cobaltite on Raman spectra is discussed and compared to experimental results from Co3O4 single crystals. We conclude that on NaCl flux grown NaxCoO2 crystals a surface layer of Co3O4 easily forms that leads to the observation of an intense phonon around 700 cm-1 [Phys. Rev. B 70, 052502 (2004)]. Raman sp

Y. Kawasaki, M. Izumi, Y. Kishimoto, T. Ohno

Sb-NMR/NQR study has revealed a formation of a pseudogap at the Fermi level in the density of states in a valence fluctuating compound CeIrSb. The nuclear spin-lattice relaxation rate divided by temperature, 1/T_1T has a maximum around 300 K and decreases significantly as 1/T_1T ~ T^2, followed by a 1/T_1T = const. relation at low temperature. This temperatu

Xiufeng Cao, Hang Zheng

The dynamics of charge qubit in double quantum dot coupled to phonons is investigated theoretically. The static bias is considered. By means of the perturbation approach based on unitary transformations, the dynamical tunneling current is obtained explicitly. The biased system displays broken symmetry and a significantly larger coherence-incoherence transiti

Thorsten Poeschel, Nikolai V. Brilliantov, Arno Formella

We present a universal description of the velocity distribution function of granular gases, $f(v)$, valid for both, small and intermediate velocities where $v$ is close to the thermal velocity and also for large $v$ where the distribution function reveals an exponentially decaying tail. By means of large-scale Monte Carlo simulations and by kinetic theory we

S. Nishimoto, T. Shirakawa, Y. Ohta

The dynamical density-matrix renormalization group technique is used to calculate spin and charge excitation spectra in the one-dimensional (1D) Hubbard model at quarter filling with nearest-neighbor $t$ and next-nearest-neighbor $t&#39;$ hopping integrals. We consider a case where $t$ ($>0$) is much smaller than $t&#39;$ ($>0$). We find that the spin and ch

Longhua Hu, Alexander Y. Grosberg

In this paper, we study the role of surface of the globule and the role of interactions with the solvent for designed sequence heteropolymers using random energy model (REM). We investigate the ground state energy and surface monomer composition distribution. By comparing the freezing transition in random and designed sequence heteropolymers, we discuss the

Hongbo Zhao, Sumit Mazumdar

We report benchmark calculations of electroabsorption in semiconducting single-walled carbon nanotubes to provide motivation to experimentalists to perform electroabsorption measurement on these systems. We show that electroabsorption can detect continuum bands in different energy manifolds, even as other nonlinear absorption measurements have failed to dete

C. Micu, E. Papp, L. Aur

Using suitable magnetic flux operators established in terms of discrete derivatives leads to quantum-mechanical descriptions of LC-circuits with an external time dependent periodic voltage. This leads to second order discrete Schrodinger equations provided by discretization conditions of the electric charge. Neglecting the capacitance leads to a simplified d

W. G. Mathews, F. Brighenti

We describe how AGN-produced cosmic rays form large X-ray cavities and radio lobes in the hot diffuse gas in galaxy groups and clusters. Cosmic rays are assumed to be produced in a small shocked region near the cavity center, such as at the working surface of a radio jet. The coupled equations for gasdynamics and cosmic ray diffusion are solved with various

L. M. Rebull, K. R. Stapelfeldt, N. J. Evans, J. K. Joergensen

We present observations of 10.6 square degrees of the Perseus molecular cloud at 24, 70, and 160 microns with the Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS). The image mosaics show prominent, complex extended emission dominated by illuminating B stars on the East side of the cloud, and by cold filaments of 160 micron emission on

Cesar Briceno, Lee Hartmann, Jesus Hernandez, Nuria Calvet

We report here on the photometric and kinematic properties of a well defined group of nearly 200 low-mass pre-main sequence stars, concentrated within ~ 1 deg of the early-B star 25 Ori, in the Orion OB1a sub-association. We refer to this stellar aggregate as the 25 Orionis group. The group also harbors the Herbig Ae/Be star V346 Ori and a dozen other early

Randall L. Cooper, Ramesh Narayan

We investigate the latitude at which type I X-ray bursts are ignited on rapidly rotating accreting neutron stars. We find that, for a wide range of accretion rates, ignition occurs preferentially at the equator, in accord with the work of Spitkovsky et al. However, for a range of accretion rates below the critical rate above which bursts cease, ignition occu

Anil Seth, Roelof De Jong, Julianne Dalcanton, the GHOSTS team

We present the preliminary detection of a stellar halo in the nearby, edge-on galaxy, NGC 4244. Using data from the Hubble Space Telescope&#39;s Advanced Camera for Surveys (HST/ACS), we have examined number counts of red giant branch (RGB) stars along the minor axis of the galaxy out to 10 kpc, with a limiting surface brightness of mu_R ~ 31 mag/arcsec^2. A

Alexander Scholz, Ray Jayawardhana, Kenneth Wood, Gwendolyn Meeus

We have carried out a Spitzer survey for brown dwarf (BD) disks in the ~5 Myr old Upper Scorpius (UpSco) star forming region, using IRS spectroscopy from 8 to 12μm and MIPS photometry at 24μm. Our sample consists of 35 confirmed very low mass members of UpSco. Thirteen objects in this sample show clear excess flux at 24μm, explained by dust emission from a c

Mercedes Lopez-Morales

The recent burst in the number of radii measurements of very low-mass stars from eclipsing binaries and interferometry of single stars has opened more questions about what can be causing the discrepancy between the observed radii and the ones predicted by the models. The two main explanations being proposed are a correlation between the radius of the stars a

Jérôme Pety, Javier R. Goicoechea, Pierre Hily-Blant, Maryvonne Gerin

Deuterium fractionation is known to enhance the [DCO+]/[HCO+] abundance ratio over the D/H elemental ratio of about 1e-5 in the cold and dense gas typically found in pre-stellar cores. We report the first detection and mapping of very bright DCO+ J=3-2 and J=2-1 lines (3 and 4 K respectively) towards the Horsehead photodissociation region (PDR) observed with

J. L. Donley, G. H. Rieke, P. G. Perez-Gonzalez, J. R. Rigby

We define a sample of 62 galaxies in the Chandra Deep Field-North whose Spitzer IRAC SEDs exhibit the characteristic power-law emission expected of luminous AGN. We study the multiwavelength properties of this sample, and compare the AGN selected in this way to those selected via other Spitzer color-color criteria. Only 55% of the power-law galaxies are dete

S. S. Larsen, M. D. Mora, J. P. Brodie, T. Richtler

We present first results from an HST/ACS imaging survey of stars and star clusters in five nearby spiral galaxies. This contribution concentrates on NGC 1313, a highly distorted late-type barred spiral. We compare the field star and cluster formation histories in our three ACS pointings for this galaxy. In one pointing, both the cluster and field star age di

Manolis Plionis, Spyros Basilakos

We review the high-redshift X-ray selected AGN clustering, based on the XMM/2dF survey, and compare it with other recent XMM-based results. Using the recent Hasinger et al. (2005) and La Franca et al. (2005) luminosity functions we find that the spatial clustering lengths, derived using Limber&#39;s inversion equation, are $\sim 17$ and 20 $h^{-1}$ Mpc for t

M. Orellana, G. E. Romero, L. J. Pellizza, S. Vidrih

Context: Some high mass X-ray binaries (HMXB) have been recently confirmed as gamma-ray sources by ground based Cherenkov telescopes. In this work, we discuss the gamma-ray emission from X-ray transient sources formed by a Be star and a highly magnetized neutron star. This kind of systems can produce variable hadronic gamma-ray emission through the mechanism

Mercedes Mollá, Eduardo Hardy, &#39;{A}ngeles I. Díaz

We have computed a grid of chemical evolution models for a large set of spiral and irregular theoretical galaxies of different total mass. In our models, the gas phase has two components, the diffuse and the molecular one ($\rm H_{2}$). It is possible, therefore, to follow the time (or redshift) evolution of the expected density of the $\rm H_{2}$ phase. We

Lawrence M. Krauss, Katherine Jones-Smith, Dragan Huterer

We focus on uncertainties in supernova measurements, in particular of individual magnitudes and redshifts, to review to what extent supernovae measurements of the expansion history of the universe are likely to allow us to constrain a possibly redshift-dependent equation of state of dark energy, $w(z)$. focus in particular on the central question of how well

Mercedes Mollá, José M. Vílchez, Angeles I. Díaz, Marta Gavilán

We study the evolution of nitrogen resulting from a set of spiral and irregular galaxy models computed for a large number of input mass radial distributions and with various star formation efficiencies. We show that our models produce a nitrogen abundance evolution in good agreement with the observational data. In particular, low N/O values for high-redshift

Paolo Serra, Rachel Bean, Axel De La Macorra, Alessandro Melchiorri

We consider the impact of the Heidelberg-Moscow claim for a detection of neutrino mass on the determination of the dark energy equation of state. By combining the Heidelberg-Moscow result with the WMAP 3-years data and other cosmological datasets we constrain the equation of state to -1.67< w <-1.05 at 95% c.l., While future data are certainly needed for a c

P. Hennebelle, A. Belloche, P. Andre, A. Whiworth

Detailed modelling of individual protostellar condensations, is important to test the various theories. Here we present comparisons between strongly induced collapse models with one young class-0, IRAS4A in the Perseus cloud and one prestellar cloud observed in the Coalsack molecular cloud.