May 2005 arXiv papers — page 18

Edmund J. Copeland, Osamu Seto

We consider the constraints that can be imposed on a wide class of Inflation models in modified gravity scenarios in which the Friedmann equation is modified by the inclusion of $ρ^2$ terms, where $ρ$ is the total energy density. In particular we obtain the reheating temperature and gravitino abundance associated with the end of inflation. Whereas models of

Audrey Cottet, Wolfgang Belzig

We reconsider the problem of the superconducting proximity effect in a diffusive ferromagnet bounded by tunneling interfaces, using spin-dependent boundary conditions. This introduces for each interface a phase-shifting conductance Gphi which results from the spin dependence of the phase shifts acquired by the electrons upon scattering on the interface. We s

Subrata Pal, Pawel Danielewicz

A statistical model for decay and formation of heavy hadronic resonances is formulated. The resonance properties become increasingly uncertain with increasing resonance mass. Drawing on analogy with the situation in low-energy nuclear physics, we employ the Weisskopf approach to the resonance processes. In the large-mass limit, the density of resonance state

Oksana Patsahan, Ihor Mryglod, Jean-Michel Caillol

The correlation functions of an ionic fluid with charge and size asymmetry are studied within the framework of the random phase approximation. The results obtained for the charge-charge correlation function demonstrate that the second-moment Stillinger-Lovett (SL) rule is satisfied away from the gas-liquid critical point (CP) but not, in general, at the CP.

Belinka Gonzalez, Santiago A. Martinez, R. Montemayor, Luis F. Urrutia

After summarizing the most interesting results in the calculation of synchrotron radiation in the Myers-Pospelov effective model for Lorentz invariance violating (LIV) electrodynamics, we present a general unified way of describing the radiation regime of LIV electrodynamics which include the following three different models : Gambini-Pullin, Ellis et al. an

M. Artuso, C. Boulahouache, S. Blusk, J. Butt

We report on test results of a novel ring imaging Cherenkov (RICH) detection system consisting of a 3 meter long gaseous C4F8O radiator, a focusing mirror, and a photon detector array based on Hamamatsu multi-anode photomultiplier tubes. This system was developed to identify charged particles in the momentum range from 3-70 GeV/c for the BTeV experiment.

Henri Johnston

Let L/K be an extension of absolutely abelian number fields of equal conductor, n. The image of the ring of integers of L under the trace map from L to K is an ideal in the ring of integers in K. We compute the absolute norm of this ideal exactly for any such L/K, thereby sharpening an earlier result of Kurt Girstmair. Furthermore, we define an "adjusted

Raphael C. Pooser, Olivier Pfister

We report the simultaneous quasi-phase-matching of all three possible nonlinearities for propagation along the X axis of periodocally poled (PP) KTiOPO4 (KTP) for second-harmonic generation of 745 nm pulsed light from 1490nm subpicosecond pulses in a PPKTP crystal with a 45.65 micrometer poling period. This confirms the recent Sellmeier fits of KTP by K. Kat

Alexei Gilchrist, A. J. F. Hayes, T. C. Ralph

We present a linear optics quantum computation scheme with a greatly reduced cost in resources compared to KLM. The scheme makes use of elements from cluster state computation and achieves comparable resource usage to those schemes while retaining the circuit based approach of KLM.

J. S. Pratt

The qubit entanglement induced by quasiparticle excitations in the Heisenberg spin chain and its relationship to the Bethe Ansatz structure of the eigenmodes is studied. A phenomenon called entanglement quenching, which suppresses eigenstate entanglement, is described and shown to be mediated by Goldstone magnons. Scattering states are characterized by short

Trinh X. Hoang, Antonio Trovato, Flavio Seno, Jayanth R. Banavar

We recently introduced a physical model [Hoang et al., P. Natl. Acad. Sci. USA (2004), Banavar et al., Phys. Rev. E (2004)] for proteins which incorporates, in an approximate manner, several key features such as the inherent anisotropy of a chain molecule, the geometrical and energetic constraints placed by the hydrogen bonds and sterics, and the role played

Pavel V. Kurakin, George G. Malinetskii

We suugest a simple hypothesis on physical origin of quantum superposition, which is a generalization of our "hidden time" hypothesis, suggested before.

Bernhard Rothenstein

We show that the transformation of relativistic velocities derived without using the Lorentz-Einstein transformation for the space-time coordinates of the same event and the fact that we can define the proper value of length, time interval, mass, electric field intensity enable us to derive transformation equations for the space-time coordinates of the same

J. R. Mureika

It is well known that ``equivalent'' sprint race times run with different accompanying wind speeds or at different altitudes are anything but equivalent races. The drag force acting on a sprinter is a function of air density and the relative wind speed, where the former has traditionally been calculated using the race venue's elevation above sea

J. R. Mureika, G. C. Cupchik, C. C. Dyer

The similarity in fractal dimensions of paint ``blobs'' in samples of gestural expressionist art implies that these pigment structures are statistically indistinguishable from one another. This result suggests that such dimensions cannot be used as a ``fingerprint'' for identifying the work of a single artist. To overcome this limitation, the

Arnt Inge Vistnes, M. Hjorth-Jensen

During the last decade we have witnessed an impressive development in so-called interpreted languages and computational environments such as Maple, Mathematica, IDL, Matlab etc. Problems which until recently were typically solved on mainframe machines and written in computing languages such as Fortran or C/C++, can now easily be solved on standard PCs with t

Abhijit Kar Gupta

The Kinetic Gas Theory like two-agent money exchange models, recently introduced in the Econophysics of Wealth distributions, are revisited. The emergence of Boltzmann-Gibbs like distribution of individual money to Pareto's law in the tail of the distribution is examined in terms of 2x2 Transition matrix with a general and simple oulook. Some additional

N. M. Zubarev

The nonlinear dynamics of the free surface of an ideal conducting liquid in a strong external electric field is studied. It is establish that the equations of motion for such a liquid can be solved in the approximation in which the surface deviates from a plane by small angles. This makes it possible to show that on an initially smooth surface for almost any

Denis Bernard

A review of the present situation and perspectives, in particular in the scope of a multi-Tev linear accelerator.

Chengling Gou

In mix-game which is an extension of minority game, there are two groups of agents; group1 plays the majority game, but the group2 plays the minority game. This paper studies the change of the average winnings of agents and volatilities vs. the change of mixture of agents in mix-game model. It finds that the correlations between the average winnings of agent

Ali Dabirian, Mahmood Akbari, Niels Asger Mortensen

The six-fold rotational symmetry of photonic crystal fibers has important manifestations in the radiated fields in terms of i) a focusing phenomena at a finite distance from the end-facet and ii) the formation of low-intensity satellite peaks in the asymptotic far field. For our study, we employ a surface equivalence principle which allows us to rigorously c

M. I. Gorenstein, M. Gazdzicki, W. Greiner

Phase diagram of strongly interacting matter is discussed within the exactly solvable statistical model of the quark-gluon bags. The model predicts two phases of matter: the hadron gas at a low temperature T and baryonic chemical potential muB, and the quark-gluon gas at a high T and/or muB. The nature of the phase transition depends on a form of the bag mas

Gerald E. Brown, Chang-Hwan Lee, Mannque Rho

Combining the recent experimental indications of density dependence in the pion decay constant $f_π^\star$ and the $ω$ meson mass $m_ω^\star$ and the discovery of $S^0 (3115)$ and other "strange nuggets" with the vector manifestation of chiral symmetry in hidden local symmetry proposed by Harada and Yamawaki, we show that the mechanism responsible fo

Henryk Fukś, Ryan Duchesne, Anna T. Lawniczak

We investigate the role of global mixing in epidemic processes. We first construct a simplified model of the SIR epidemic using a realistic population distribution. Using this model, we examine possible mechanisms for destruction of spatial correlations, in an attempt to produce correlation curves similar to those reported recently for real epidemiological d

Mason A. Porter, Peter J. Mucha, M. E. J. Newman, Casey M. Warmbrand

Network theory provides a powerful tool for the representation and analysis of complex systems of interacting agents. Here we investigate the United States House of Representatives network of committees and subcommittees, with committees connected according to ``interlocks'' or common membership. Analysis of this network reveals clearly the strong li

Alex veksler, Yair Zarmi

The construction of a solution of the perturbed KdV equation encounters obstacles to asymptotic integrability beyond the first order, when the zero-order approximation is a multiple-soliton wave. In the standard analysis, the obstacles lead to the loss of integrability of the Normal Form, resulting in a zero-order term, which does not have the simple structu

Bo Hu, Gang Yan, Wen-Xu Wang, Wen Chen

We will introduce two evolving models that characterize weighted complex networks. Though the microscopic dynamics are different, these models are found to bear a similar mathematical framework, and hence exhibit some common behaviors, for example, the power-law distributions and evolution of degree, weight and strength. We also study the nontrivial clusteri

Michael Kastner, Jacques-Alexandre Sepulchre

For the Fermi-Pasta-Ulam chain, an effective Hamiltonian is constructed, describing the motion of approximate, weakly localized discrete breathers traveling along the chain. The velocity of these moving and localized vibrations can be estimated analytically as the group velocity of the corresponding wave packet. The Peierls-Nabarro barrier is estimated for s

Lukasz Bratek

It is shown how the appearance of the 1-skyrmion on the three-sphere of radius L can be understood quantitatively by analyzing spectrum of the Hessian at the identity solution. Previously, this analysis was done qualitatively by N. Manton which used a conformal deformation of the identity solution.

Stephen Parrott

Over 60 years ago, Eliezer proved the surprising result that an electron moving radially according to the Lorentz-Dirac equation in the Coulomb field of a proton will not be attracted to a collision with the proton as expected. Instead, it is repelled from the proton with proper acceleration increasing asymptotically with proper time. Proponents of the Loren

Feng Xu

In this paper we prove a general theorem on the extensions of local nets which was inspired by recent examples of exotic extensions for Virasoro nets with central charge less than one and earlier work on cosets and conformal inclusions. When applying the theorem to conformal inclusions and diagonal inclusions, we obtain infinite series of new examples of com

Ana Cannas da Silva

This is an overview article on selected topics in symplectic geometry written for the Handbook of Differential Geometry (volume 2, edited by F.J.E. Dillen and L.C.A. Verstraelen).

Jordan Rizov

Let $X$ be a scheme over a field $K$ and let $M_X$ be the intersection of all subfields $L$ of $\bar K$ such that $X$ has a $L$-valued point. In this note we prove that for a variety $X$ over a field $K$ finitely generated over its prime field one has that $M_X = K$

Mladen Bestvina, Mark Feighn

Let F be a non-abelian finite rank free group, and let H_g be the fundamental group of a surface of genus g with one boundary component represented by D_g in H_g. So, H_g is the free group <a_1,b_1,...,a_g,b_g> and D_g is the product of commutators [a_1,b_1]...[a_g,b_g]. Given x in F, we are interested in the number num(x) of primitive, i.e. root-free, image

Yu Zou, Ioannis Kevrekidis, Roger Ghanem

We present an equation-free dynamic renormalization approach to the computational study of coarse-grained, self-similar dynamic behavior in multidimensional particle systems. The approach is aimed at problems for which evolution equations for coarse-scale observables (e.g. particle density) are not explicitly available. Our illustrative example involves Brow

José J. Ramón-Marí

In this paper we prove the Hodge conjecture for products of the form $S_1 \times ... S_n$, where $S_i$ are smooth projective surfaces such that $p_g(S_i)=1, q(S_i)=2$. We also prove the Hodge conjecture for arbitrary self-products of a K3 surface $X$ such that $End_{hodge}(T(X))$ is a CM number field.

C. Deninger

This report on the topics in the title was written for a lecture series at the Southwestern Center for Arithmetic Algebraic Geometry at the University of Arizona.It may serve as an introduction to certain conjectural relations between number theory and the theory of dynamical systems on foliated spaces. The material is based on streamlined and updated versio

Iasson Karafyllis

In this paper the notions of non-uniform in time Robust Blobal Asymptotic Output Stability (RGAOS) and Input-to-Output Stability (IOS) for discrete-time systems are studied. Characterizations as well as links between these notions are provided. Particularly, it is shown that a discrete-time system with continuous dynamics satisfies the non-uniform in time IO

Kazushi Ueda

We prove the conjectural relation between the Stokes matrix for the quantum cohomology and an exceptional collection generating the derived category of coherent sheaves in the case of smooth cubic surfaces. The proof is based on a toric degeneration of cubic surfaces, the Givental&#39;s mirror theorem for toric manifolds, and the Picard-Lefschetz theory.

Mark B. Villarino

We present a self-contained elementary and detailed exposition of Mertens&#39; own proof of his theorem on the divergence of the series of the reciprocals of the primes and compare it with the modern proofs. His proof contains explicit numerical error estimates and computations of the Mertens &#34;constant,&#34; both of which are missing from modern expositi

Hjalmar Rosengren

We show that the denominator formula for the strange series of affine superalgebras, conjectured by Kac and Wakimoto and proved by Zagier, follows from a classical determinant evaluation of Frobenius. As a limit case, we obtain exact formulas for the number of representations of an arbitrary number as a sum of 4m^2/d triangles, whenever d divides 2m, and 4m(

Shlomo Hoory, Nathan Linial

Associated with every graph $G$ of chromatic number $χ$ is another graph $G&#39;$. The vertex set of $G&#39;$ consists of all $χ$-colorings of $G$, and two $χ$-colorings are adjacent when they differ on exactly one vertex. According to a conjecture of Björner and Lovász, this graph $G&#39;$ must be disconnected. In this note we give a counterexample to this

Scott Crass

The symmetric group S_n acts as a reflection group on CP^{n-2} (for $n\geq 3$) . Associated with each of the $\binom{n}{2}$ transpositions in S_n is an involution on CP^{n-2} that pointwise fixes a hyperplane--the mirrors of the action. For each such action, there is a unique S_n-symmetric holomorphic map of degree n+1 whose critical set is precisely the col

Lisa C. Jeffrey, Young-Hoon Kiem, Frances Kirwan, Jonathan Woolf

In this paper we shall give formulas for the pairings of intersection cohomology classes of complementary dimensions in the intersection cohomology of geometric invariant theoretic quotients for which semistability is not necessarily the same as stability (although we make some weaker assumptions on the action). We also give formulas for intersection pairing

Andrew J. Tolley

We consider the propagation of classical and quantum strings on cosmological space-times which interpolate from a collapsing phase to an expanding phase. We begin by considering the classical propagation of strings on space-times with isotropic and anisotropic cosmological singularities. We find that cosmological singularities fall into two classes, in the f

Matthew J. Strassler

The duality cascade, and its dual description as string theory on the warped deformed conifold, brings together several sophisticated topics, some of which are not widely known. These lectures, which contain a number of previously unpublished results, and are intended for experts as well as students, seek to explain the physics of duality cascades. Seiberg d

Forough Nasseri

We calculate the fine structure constant in the spacetime of a cosmic string. In the presence of a cosmic string the value of the fine structure constant reduces. We also discuss on numerical results.

Fabio Cardone, Alessio Marrani, Roberto Mignani

We illustrate the main features of a new Kaluza-Klein-like scheme (Deformed Relativity in five dimensions). It is based on a five-dimensional Riemannian space in which the four-dimensional space-time metric is deformed (i.e. it depends on the energy) and energy plays the role of the fifth dimension. We review the solutions of the five-dimensional Einstein eq

Yong Ding, Rong-Guang Xu, Bo-Qiang Ma

The asymmetries of both light-flavor antiquark $\bar{d}(x)-\bar{u}(x)$ and strange-antistrange $s(x)-\bar{s}(x)$ distributions of the nucleon sea are considered with more details in the effective chiral quark model. We find that the asymmetric distribution of light-flavor antiquarks $\bar{d}(x)-\bar{u}(x)$ matches the experiment data well and that the asymme

A. Tawfik, D. Toublan

We use a hadron resonance gas model to calculate the quark-antiquark condensates for light (up and down) and strange quark flavors at finite temperatures and chemical potentials. At zero chemical potentials, we find that at the temperature where the light quark-antiquark condensates entirely vanish the strange quark-antiquark condensate still keeps a relativ

Shaaban Khalil

We analyze the supersymmetric contributions to the direct and mixing CP asymmetries and also to the branching ratios of the B --> K πdecays in a model independent way. We consider both gluino and chargino exchanges and emphasize that a large gluino contribution is essential for saturating the direct and mixing CP asymmetries. We also find that combined contr

Ph. Boucaud, F. De Soto, A. Le Yaouanc, J. P. Leroy

Strong coupling constant computed in Landau gauge and MOM renormalization scheme from lattice two and three gluon Green Functions exhibits an unexpected behavior in the deep IR, showing a maximum value around $1 {\rm GeV}$. We analise this coupling below this maximum within a semiclassical approach, were gluon degrees of freedom at very low energies are desc

Sergio Pastor

Cosmology can provide information on the absolute scale of neutrino masses, complementary to the results of tritium beta decay and neutrinoless double beta decay experiments. We show how the analysis of data from the anisotropies of the cosmic microwave background radiation and from the distribution of cosmological large-scale structure, combined with other

Redamy Perez Ramos

We study the correlation between two soft particles in QCD jets. We extend the Fong--Webber analysis to the region away from the hump in the single inclusive energy spectrum and show that the correlation function should flatten off and then decrease for large values of l=ln(1/x).

N. N. Achasov, A. A. Kozhevnikov

Taking into account the new data on the full width of D^{\ast\pm}(2010) and the mass difference of the charged and neutral beauty mesons B^\pm, B^0,\bar B^0, the branching ratios of the decays psi(3770), Upsilon(10580) to pi^+pi^-, K bar K, rho(omega)pi, rho(omega)eta, rho(omega)eta^prime, K^ast bar K+ c.c, rho^+ rho^-, and K^ast bar K^ast are re-evaluated i

Giulia Manca

The Run II physics programme of the Tevatron is proceeding with more than 300 pb-1 of analysis quality data, collected at a centre-of-mass energy of 1.96 TeV. Searches for supersymmetric particles are starting to set new limits, improving over the LEP and Run I results and exploring new regions of parameter space. We present recent results in Supersymmetry w

Tommaso Dorigo

The CDF and D0 experiments at the Tevatron have searched for the Standard Model Higgs boson in data collected between 2001 and 2004. Upper limits have been placed on the production cross section times branching ratio to b-antib pairs or WW pairs as a function of the Higgs boson mass. Projections indicate that the Tevatron experiments have a chance of discove

Paolo Lenisa, Frank Rathmann

The document describes the physics case of the PAX experiment using polarized antiprotons, which has recently been proposed for the new Facility for Antiprotons and Ions Research (FAIR) at GSI--Darmstadt. Polarized antiprotons provide access to a wealth of single-- and double--spin observables, thereby opening a new window to physics uniquely accessible at t

TA Girard, F. Giuliani, T. Morlat, M. Felizardo da Costa

We report an improved SIMPLE experiment comprising four superheated droplet detectors with a total exposure of 0.42 kgd. The result yields ~ factor 10 improvement in the previously-reported results, and -- despite the low exposure -- is seen to provide restrictions on the allowed phase space of spin-dependent coupling strengths almost equivalent to those fro

Gilles De Lentdecker

We present some precision measurements on electroweak physics performed at the Tevatron collider at Fermilab. Namely we report on the boson-pair production cross sections and on triple gauge boson couplings using proton anti-proton collisions collected by the CDF and D0 experiments at the center-of-mass energy of 1.96 TeV. The data correspond to an integrate

R. Shahoyan, R. Arnaldi, K. Banicz, J. Castor

The NA60 experiment at the CERN-SPS is devoted to the study of dimuon production in heavy-ion and proton-nucleus collisions. We present preliminary results from the analysis of Indium-Indium collisions at 158 GeV per nucleon. The topics covered are low mass vector meson production, J/psi production and suppression, and the feasibility of the open charm measu

Sergio del Campo, Ramon Herrera

In this paper we study a type of model for closed inflationary universe models using the Jordan-Brans-Dicke theory. Herein we determine and characterize the existence of $Ω>$1, together with the period of inflation. We have found that our model, which takes into account a Jordan-Brans-Dicke type of theory, is less restrictive than the one used in Einstein&#3

J. R. Mureika, C. C. Dyer

The multifractal spectrum of various three-dimensional representations of Packed Swiss Cheese cosmologies in open, closed, and flat spaces are measured, and it is determined that the curvature of the space does not alter the associated fractal structure. These results are compared to observational data and simulated models of large scale galaxy clustering, t

Curt Cutler, Iraj Gholami, Badri Krishnan

We formulate and optimize a computational search strategy for detecting gravitational waves from isolated, previously-unknown neutron stars (that is, neutron stars with unknown sky positions, spin frequencies, and spin-down parameters). It is well known that fully coherent searches over the relevant parameter-space volumes are not computationally feasible, a

S. Ghassemi, S. Khakshournia, R. Mansouri

Considering a planar gravitating thick domain wall of the $λϕ^4$ theory, we demonstrate how the Darmois junction conditions written on the boundaries of the thick wall with the embedding spacetimes reproduce the Israel junction condition across the wall when one takes its thin wall limit.

Scott Funkhouser

Mach&#39;s &#34;fixed stars&#34; are actually not fixed at all. The distant clusters of galaxies are not only receding from each observer but they are also accelerating since the rate of cosmological expansion is not constant. If the distant cosmic masses in someway constitute the frame of inertial reference then an additional force should be generated among

K Madhava Krishna, Henry Hexmoor, Shravan Sogani

This paper presents a methodology for optimal target detection in a multi sensor surveillance system. The system consists of mobile sensors that guard a rectangular surveillance zone crisscrossed by moving targets. Targets percolate the surveillance zone in a poisson fashion with uniform velocities. Under these statistics this paper computes a motion strateg

Riccardo Capovilla, Jemal Guven

The Helfrich-Canham bending energy is identified with a non-linear sigma model for a unit vector. The identification, however, is dependent on one additional constraint: that the unit vector be constrained to lie orthogonal to the surface. The presence of this constraint adds a source to the divergence of the stress tensor for this vector so that it is not c

S. -W. Tsai, A. H. Castro Neto, R. Shankar, D. K. Campbell

We present the numerical solution of the renormalization group (RG) equations derived in Ref. [1], for the problem of superconductivity in the presence of both electron-electron and electron-phonon coupling at zero temperature. We study the instability of a Fermi liquid to a superconductor and the RG flow of the couplings in presence of retardation effects a

S. Gayen

We consider a strongly correlated ladder with diagonal hopping and exchange interactions described by $t-J$ type hamiltonian. We study the dynamics of a single hole in this model in the presence of a static non-magnetic (or magnetic) impurity. In the case of a non-magnetic (NM) impurity we solve the problem analytically both in the triplet (S=1) and singlet

E. M. Kim, S. S. Elovikov, T. V. Murzina, A. A. Nikulin

Surface-enhanced optical third-harmonic generation (THG) is observed in silver island films. The THG intensity from Ag nanoparticles is enhanced by more than two orders of magnitude with respect to the THG intensity from a smooth and homogeneous silver surface. This enhancement is attributed to local plasmon excitation and resonance of the local field at the

Wen-Xu Wang, Bo Hu, Bing-Hong Wang, Gang Yan

In most networks, the connection between a pair of nodes is the result of their mutual affinity and attachment. In this letter, we will propose a Mutual Attraction Model to characterize weighted evolving networks. By introducing the initial attractiveness $A$ and the general mechanism of mutual attraction (controlled by parameter $m$), the model can naturall

A. Otop, S. Süllow, M. B. Maple, A. Weber

We present a detailed study on the (magneto)transport properties of as-cast and heat treated material UCu$_4$Pd. We find a pronounced sample dependence of the resistivity $ρ$ of as-cast samples, and reproduce the annealing dependence of $ρ$. In our study of the Hall effect we determine a metallic carrier density for all samples, and a temperature dependence

Bo Hu, Gang Yan, Wen-Xu Wang, Wen Chen

We will introduce two evolving models that characterize weighted complex networks. Though the microscopic dynamics are different, these models are found to bear a similar mathematical framework, and hence exhibit some common behaviors, for example, the power-law distributions and evolution of degree, weight and strength. We also study the nontrivial clusteri

Z. Akdeniz, P. Vignolo, M. P. Tosi

We present analytical expressions and numerical illustrations for the ground-state density distribution of an ideal gas of spin-polarized fermions moving in two dimensions and driven to rotate in a harmonic well of circular or elliptical shape. We show that with suitable choices of the strength of the Lorentz force for charged fermions, or of the rotational

Valerij S. Egorov

The paper, not pretending for a complete and detailed review, is intended mainly for a wide community of physicists, not only specialists in this particular subject. The author gives a physical picture of the periodic emergence of instabilities and well-known diamagnetic domains (Condon domains) in metals resulting from the strong de Haas-van Alphen effect.

Munehisa Matsumoto, Hajime Takayama

We study the impurity-induced phase transitions in a quasi-one-dimensional Heisenberg antiferromagnet doped with magnetic spin-1/2 impurities and non-magnetic ones. The impurity-induced transition temperature determined by the quantum Monte Carlo method with the continuous-time loop algorithm is monotonically increasing as a function of the magnitude of the

Martin R. Galpin, David E. Logan, H. R. Krishnamurthy

We investigate two equivalent, capacitively coupled semiconducting quantum dots, each coupled to its own lead, in a regime where there are two electrons on the double dot. With increasing interdot coupling a rich range of behavior is uncovered: first a crossover from spin- to charge-Kondo physics, via an intermediate SU(4) state with entangled spin and charg

Yoshihiro Shimomura, Shin Miyahara, Nobuo Furukawa

We investigate a detail of a dodecamer cluster ordering in a double-exchange spin ice model on a kagomé lattice. In frustrated systems, ordinary spin orderings are suppressed and macroscopic degeneracy remains down to low temperatures. In some frustrated systems, the degeneracy is lifted due to residual interactions and cluster orderings are stabilized. In t

Anja Grage, Florian Gebhard, Joerg Rissler

For the one-dimensional, extended Peierls--Hubbard model we calculate analytically the ground-state energy and the single-particle gap to second order in the Coulomb interaction for a given lattice dimerization. The comparison with numerically exact data from the Density-Matrix Renormalization Group shows that the ground-state energy is quantitatively reliab

E. Z. Meilikhov

We investigate properties of two-dimensional finite-scale percolation systems whose size along the current flow is smaller than the perpendicular size. Successive thresholds of appearing multiple percolation channels in such systems have been determined and dependencies of the conductance on their size and percolation parameter $p$ have been calculated. Vari

Xiangang Wan, Masanori Kohno, Xiao Hu

The new perovskite cuprate material Sr$_{8}$CaRe$_{3}$Cu$_{4}$O$_{24}$, which behaves ferrimagnetically and shows an unusually high Curie temperature ($T_c \sim$ 440 K), is found from density-functional theory calculation to display several surprising properties after hole doping or chemical substitution: (1) Half metal (HM) is realized by replacing Re with

P. K. Siwach, H. K. Singh, O. N. Srivastava

Polycrystalline thin films of double layer manganite La_1.4Ca_1.6Mn_2O_7 (DLCMO) have been deposited by nebulized spray pyrolysis on single crystal LaAlO_3 substrates. These single phase films having grain size in the range 70-100 nm exhibit ferromagnetic transition at T_C ~ 107K. The short range ferromagnetic ordering due to in plane spin coherence is evide

Pavel Zakharov, Suresh Bhat, Peter Schurtenberger, Frank Scheffold

We introduce a charge coupled device (CCD) camera based detection scheme in dynamic light scattering that provides information on the single-scattered auto-correlation function even for fairly turbid samples. It is based on the single focused laser beam geometry combined with the selective cross correlation analysis of the scattered light intensity. Using a

Jian Wang, Jian-Sheng Wang

We derive expressions for energy flow in terms of lattice normal mode coordinates and energy transmission involving reduced group velocities. With a version of Landauer formula appropriate for lattice dynamic approach, the phonon transmission coefficients and thermal conductance are calculated for two kinds of acoustically mismatched junctions: different chi

Y. M. Liu, G. M. Huang, C. G. Bao

Based on symmetry constraint that leads to the appearance of nodes in the wave functions of 3-electron systems at regular triangle configurations, it was found that, if the parameters of confinement are skillfully given and if a magnetic field is tuned around the critical point of the singlet-triplet transition, a 2-electron quantum dot can be used as a high

S. Takahashi, S. Hill, S. Takasaki, J. Yamada

We report the observation of cyclotron resonance (CR) in a metal possessing pure quasi-one-dimensional Fermiology - namely, the organic linear-chain compound (TMTSF)2ClO4, whose Fermi surface consists of a pair of weakly warped sheets. The CR phenomenon is related to weak inter-chain coupling, which allows electrons constrained on open trajectories to acquir

G. H. A. Roelofs, P. J. Groot, T. R. Marsh, D. Steeghs

We present high time resolution VLT spectroscopy of SDSS J124058.03-015919.2, a new helium-transferring binary star identified in the Sloan Digital Sky Survey. We measure an orbital period of 37.355+/-0.002 minutes, confirming the AM CVn nature of the system. From the velocity amplitudes of the accretor and the accretion stream--disc impact, we derive a mass

M. C. Fleenor, J. A. Rose, W. A. Christiansen, R. W. Hunstead

We present 547 optical redshifts obtained for galaxies in the region of the Horologium-Reticulum Supercluster (HRS) using the 6dF multi-fiber spectrograph on the UK Schmidt Telescope at the Anglo Australian Observatory. The HRS covers an area of more than 12deg x 12deg on the sky centered at approximately RA = 03h19m, DEC = -50deg 02amin. Our 6dF observation

J. J. Fortney, M. S. Marley, K. Lodders, D. Saumon

We present new self-consistent atmosphere models for transiting planets TrES-1 and HD209458b. The planets were recently observed with the Spitzer Space Telescope in bands centered on 4.5 and 8.0 $μ$m, for TrES-1, and 24 $μ$m, for HD209458b. We find that standard solar metallicity models fit the observations for HD209458b. For TrES-1, which has an T_eff ~300

R. T. Zavala, G. B. Taylor

Using high frequency (12-22 GHz) VLBA observations we confirm the existence of a Faraday rotation measure gradient of ~ 500 rad/m^2/mas transverse to the jet axis in the quasar 3C 273. The gradient is seen in two epochs spaced roughly six months apart. This stable transverse rotation measure gradient is expected if a helical magnetic field wraps around the j

Kim-Vy H. Tran, Pieter van Dokkum, Marijn Franx, Garth D. Illingworth

We present follow-up spectroscopy of the galaxy cluster MS1054-03 (z=0.83) confirming that at least six of the nine merging galaxy pairs identified by van Dokkum et al. (1999) are indeed bound systems: they have projected separations of R_s<10 kpc and relative line-of sight velocities of dv<165 km/s. For the remaining three pairs, we were unable to obtain re

Steve Croft, Jaron Kurk, Wil van Breugel, S. A. Stanford

PKS 1138-262 is a massive radio galaxy at z = 2.16 surrounded by overdensities of Lya emitters, Ha emitters, EROs and X-ray emitters. Numerous lines of evidence exist that it is located in a forming cluster. We report on Keck spectroscopy of candidate members of this protocluster, including nine of the 18 X-ray sources detected by Pentericci et al. (2002) in

E. Verner, F. Bruhweiler, K. E. Nielsen, T. R. Gull

The very massive star, Eta Carinae, is enshrouded in an unusual complex of stellar ejecta, which is highly depleted in C and O, and enriched in He and N. This circumstellar gas gives rise to distinct absorption components corresponding to at least 20 different velocities along the line-of-sight. The velocity component at -513 kms-1 exhibits very low ionizati

W. R. T. Edge, M. J. Coe, J. L. Galache, V. A. McBride

A probable binary period has been detected in the optical counterpart to the X-ray source CXOU J005455.6-724510 = RX J0054.9-7245 = AXJ0054.8-7244 = SXP504 in the Small Magellanic Cloud. This source was detected by Chandra on 04 Jul 2002 and subsequently observed by XMM-Newton on 18 Dec 2003. The source is coincident with an Optical Gravitational Lensing (OG

P. Blasi, S. Gabici, G. Vannoni

The dynamical reaction of the particles accelerated at a shock front by the first order Fermi process can be determined within kinetic models that account for both the hydrodynamics of the shocked fluid and the transport of the accelerated particles. These models predict the appearance of multiple solutions, all physically allowed. We discuss here the role o

Andreas Seifahrt, Eike Guenther, Ralph Neuhaeuser

We present astrometric and photometric measurements of the field binary L1 dwarf DENIS-P J1441-0945. Analysis of archival HST images and photometric parallax measurements give a distance of 34+/-7 pc and a proper motion close to that of the nearby high proper motion star G124-62. Comparison of SuperCOSMOS and 2MASS images confirms that these objects form a c

Yosuke Minowa, Naoto Kobayashi, Yuzuru Yoshii, Tomonori Totani

We present a deep $K^{\prime}$-band (2.12$μ$m) imaging of 1\arcmin\ $\times$ 1\arcmin Subaru Super Deep Field (SSDF) taken with the Subaru adaptive optics (AO) system. Total integration time of 26.8 hours results in the limiting magnitude of $K^{\prime} \sim 24.7$ (5$σ$, 0\farcs2 aperture) for point sources and $K^{\prime} \sim 23.5$ (5$σ$, 0\farcs6 aperture

F. D&#39;Antona, M. Bellazzini, V. Caloi, F. Fusi Pecci

We studied the color distribution of the main sequence of the Globular Cluster NGC 2808, based on new deep HST-WFPC2 photometry of a field in the uncrowded outskirts of the cluster. The color distribution of main sequence stars is wider than expected for a single stellar population, given our (carefully determined) measurement errors. About 20% of the sample

Edwin A. Bergin, Gary J. Melnick, Perry A. Gerakines, David A. Neufeld

We present the first Spitzer Infrared Spectrograph observations of the 15.2 micron bending mode of CO2 ice towards field stars behind a quiescent dark cloud. CO2 ice is detected towards 2 field stars (Elias 16, Elias 3) and a single protostar (HL Tau) with anabundance of ~15-20% relative to water ice. CO2 ice is not detected towards the source with lowest ex