January 2004 arXiv papers — page 7

Maximilian Schlosshauer, David Baker

We present a general expression for the association rate for partially diffusion-controlled reactions between spherical molecules with an asymmetric reactive patch on each surface. Reaction can occur only if the two patches are in contact and properly aligned to within specified angular tolerances. This extends and generalizes previous approaches that consid

Aleksandar Gjurchinovski

We developed a specific numerical fitting procedure, based on the least squares method, to calculate the parameters of the polarization ellipse by only using a single polarizer and a detection device for measuring the outgoing intensities.

G. Pontuale, F. A. Farrelly, A. Petri, L. Pitolli

The statistical properties of acoustic emission signals for tool condition monitoring (TCM) applications in mechanical lathe machining are analyzed in this paper. Time series data and root mean square (RMS) values at various tool wear levels are shown to exhibit features that can be put into relation with ageing in both cases. In particular, the histograms o

Gerhard Baur, Stefan Typel

The Trojan-Horse method is an indirect approach to determine the energy dependence of S factors of astrophysically relevant two-body reactions. This is accomplished by studying closely related three-body reactions under quasi-free scattering conditions. The basic theory of the Trojan-Horse method is developed starting from a post-form distorted wave Born app

A. Drago, A. Lavagno, G. Pagliara

We show that if color superconducting quark matter forms in hybrid or quark stars it is possible to satisfy most of recent observational boundaries on masses and radii of compact stellar objects. An energy of the order of $10^{53}$ erg is released in the conversion from a (metastable) hadronic star into a (stable) hybrid or quark star in presence of a color

Yu. E. Titarenko, V. F. Batyaev, E. I. Karpikhin, V. M. Zhivun

Threshold activation reaction rates in 12C, 19F, 27Al, 59Co, 63Cu, 65Cu, 64Zn, 93Nb, 115In, 169Tm, 181Ta, 197Au, and 209Bi experimental samples placed along the axis inside and outside the 0.8 GeV proton-irradiated 92-cm thick W-Na and 4-cm thick W targets where measured at the ITEP proton synchrotron. 158 reactions of up to +AH4-0.5 GeV thresholds have been

Yu. E. Titarenko, V. F. Batyaev, E. I. Karpikhin, V. M. Zhivun

The ITEP proton synchrotron U10 was used to irradiate isotopically-enriched 208Pb and natU thin targets with 1.0 GeV protons and 197Au thin targets with 0.8 GeV protons. More than 400 cross sections of the nuclides produced were measured using the direct spectrometry method with a high-resolution Ge detector. The measured cross sections are compared with sim

V. Avdeichikov, R. Ghetti, J. Helgesson, B. Jakobsson

Single-particle kinetic energy spectra and two-particle small angle correlations of protons ($p$), deuterons ($d$) and tritons ($t$) have been measured simultaneously in 61A MeV $^{36}$Ar + $^{27}$Al, $^{112}$Sn and $^{124}$Sn collisions. Characteristics of the emission sources have been derived from a ``source identification plot'' ($β_{source}$--$E

Charles F. F. Karney

In the study of long-time correlations extremely long orbits must be calculated. This may be accomplished much more reliably using fixed-point arithmetic. Use of this arithmetic on the Cray-1 computer is illustrated.

Holger Brenner

We give an example of a strongly semistable vector bundle of rank two on the projective plane such that there exist smooth curves of arbitrary high degree with the property that the restriction of the bundle to the curve is not strongly semistable anymore. This shows that a Bogomolov type restriction theorem does not hold for strong semistability in positive

R. R. Isangulov

There is a well-known problem about isospectrality of Riemannian manifolds: whether isospectral manifolds are isometric. In this work we give an answer to this problem for 3-dimensional compact flat manifolds.

Frank Harary, Wolfgang Slany, Oleg Verbitsky

Given a graph $G$, we consider a game where two players, $A$ and $B$, alternatingly color edges of $G$ in red and in blue respectively. Let $l(G)$ be the maximum number of moves in which $B$ is able to keep the red and the blue subgraphs isomorphic, if $A$ plays optimally to destroy the isomorphism. This value is a lower bound for the duration of any avoidan

Pietro Corvaja, Umberto Zannier

Generalizing a result of Pourchet, we prove that, if $α,β$ are power sums satisfying suitable conditions, the length of the continued fraction of the ratio $α(n)/β(n)$ tends to infinity with $n$.

Oleg Verbitsky

We say that a first order formula $Φ$ defines a graph $G$ if $Φ$ is true on $G$ and false on every graph $G'$ non-isomorphic with $G$. Let $D(G)$ be the minimal quantifier rank of a such formula. We prove that, if $G$ is a tree of bounded degree or a Hamiltonian (equivalently, 2-connected) outerplanar graph, then $D(G)=O(\log n)$, where $n$ denotes the o

Genevra Neumann

The valence of a function $f$ at a point $w$ is the number of distinct, finite solutions to $f(z) = w$. Let $f$ be a complex-valued harmonic function in an open set $R \subseteq \mathbb{C}$. Let $S$ denote the critical set of $f$ and $C(f)$ the global cluster set of $f$. We show that $f(S) \cup C(f)$ partitions the complex plane into regions of constant vale

Nikolaj Glazunov

We present a combinatorial geometry and dynamical systems framework for the investigation and proof of the Minkowski conjecture about critical determinant of the region $ |x|^p + |y|^p < 1, p > 1. $ The application of the framework may drastically reduce the investigation of sufficiently smooth real functions of many variables. Incidentally, we establish con

Joseph H. Silverman

Ailon and Rudnick have shown that if $a,b \in C[T]$ are multiplicatively independent polynomials, then $°(\gcd(a^n-1,b^n-1))$ is bounded for all $n\ge1$. We show that if instead $a,b \in F[T]$ for a finite field $F$ of characteristic $p$, then $°(\gcd(a^n-1,b^n-1))$ is larger than $Cn$ for a constant $C=C(a,b)>0$ and for infinitely many $n$, even if $n$ is r

A. B. Goncharov

We define Euclidean scissor congruence groups for an arbitrary algebraically closed field F and propose their conjectural description. We suggest how they should be related to mixed Tate motives over dual numbers for F.

Nicolas Lanchier

We study a generalization of the two colors multitype contact process intended to mimic an example of interspecific competition called allelopathy.

Meirav Amram, David Garber, Mina Teicher

This paper is the first part of a series of three papers about the fundamental groups of conic-line arrangements consist of two tangented conics and up to two additional tangented lines. In this part, we compute the local braid monodromies and the local fundamental groups of the singularities which appear in such arrangements.

Michael Huber

We solve the long-standing open problem of classifying all 3-(v,k,1) designs with a flag-transitive group of automorphisms (cf. A. Delandtsheer, Geom. Dedicata 41 (1992), p. 147; and in: &#34;Handbook of Incidence Geometry&#34;, ed. by F. Buekenhout, Elsevier Science, Amsterdam, 1995, p. 273; but presumably dating back to 1965). Our result relies on the clas

Alexei Yu. Karlovich, Andrei K. Lerner

A classical theorem of Coifman, Rochberg, and Weiss on commutators of singular integrals is extended to the case of generalized $L^p$ spaces with variable exponent.

Yann Bugeaud, Florian Luca

In this paper, we prove that the period of the continued fraction expansion of ${\sqrt {2^{n}+1}}$ tends to infinity when $n$ tends to infinity through odd positive integers.

Arnaud Bodin

We consider a continuous family $(f_s)$, $s\in[0,1]$ of complex polynomials in two variables with isolated singularities, that are Newton non-degenerate. We suppose that the Euler characteristic of a generic fiber is constant (or equivalently the sum of the affine Milnor number and the Milnor number at infinity $μ(s)+λ(s)$ is constant). We firstly prove that

William Arveson

We show that for every &#34;locally finite&#34; unit-preserving completely positive map P acting on a C*-algebra, there is a corresponding *-automorphism αof another unital C*-algebra such that the two sequences P, P^2,P^3,... and α, α^2,α^3,... have the same {\em asymptotic} behavior. The automorphism αis uniquely determined by P up to conjugacy. Similar re

Ada Chan, Chris Godsil

In 1989, Vaughan Jones introduced spin models and showed that they could be used to form link invariants in two different ways--by constructing representations of the braid group, or by constructing partition functions. These spin models were subsequently generalized to so-called 4-weight spin models by Bannai and Bannai; these could be used to construct par

S. G. Rajeev

We show how to formulate Yang-Mills Theory in \m{2+1} dimensions as a hamitonian system within a simplicial regularization and construct its quantization, with special attention to the mass gap. An approximate conformal invariance of the hamiltonian of this theory is useful to construct a continuum limit.

P. Aschieri, J. Madore, P. Manousselis, G. Zoupanos

We combine and exploit ideas from Coset Space Dimensional Reduction (CSDR) methods and Non-commutative Geometry. We consider the dimensional reduction of gauge theories defined in high dimensions where the compact directions are a fuzzy space (matrix manifold). In the CSDR one assumes that the form of space-time is M^D=M^4 x S/R with S/R a homogeneous space.

Branko Dragovich, Zoran Rakic

We consider Feynman&#39;s path integral approach to quantum mechanics with a noncommutativity in position and momentum sectors of the phase space. We show that a quantum-mechanical system with this kind of noncommutativity is equivalent to the another one with usual commutative coordinates and momenta. We found connection between quadratic classical Hamilton

Igor Schnakenburg, Peter West

A description of the bosonic sector of ten-dimensional N=1 supergravity as a non-linear realisation is given. We show that if a suitable extension of this theory were invariant under a Kac-Moody algebra, then this algebra would have to contain a rank eleven Kac-Moody algebra, that can be identified to be a particular real form of very-extended D_8. We also d

M. M. Akbar, P. D. D&#39;Eath

We find instanton/cosmological solutions with biaxial Bianchi-IX symmetry, involving non-trivial spatial dependence of the $\bbbc P^{1}$- and $\bbbc P^{2}$-sigma-models coupled to gravity. Such manifolds arise in N=1, $d=4$ supergravity with supermatter actions and hence the solutions can be embedded in supergravity. There is a natural way in which the stand

Chethan N. Gowdigere, Dennis Nemeschansky, Nicholas P. Warner

We give a general framework for constructing supersymmetric solutions in the presence of non-trivial fluxes of tensor gauge fields. This technique involves making a general Ansatz for the metric and then defining the Killing spinors in terms of very simple projectors on the spinor fields. These projectors and, through them, the spinors, are determined algebr

Scott A. Yost, Chris Glosser, B. F. L. Ward

We have used YFS Monte Carlo techniques to obtain per-mil level accuracy for the Bhabha scattering cross section used in the luminosity monitor in electro-weak scattering experiments. We will describe techniques for extending these methods for use in the W production luminosity cross section for hadron colliders.

J. D&#39;Hondt

Two measurements are presented of estimators sensitive to the Colour Reconnection effect in WW events at LEP2. The results are compared with various phenomenological Monte Carlo implementations of the effect. A feasibility study is performed to reduce the total uncertainty in the direct W boson mass measurement at LEP2 by use of the inferred information abou

J. Gasser, A. Rusetsky, J. Schacher

These are the proceedings of the workshop &#34;HadAtom03,&#34; held at the European Centre for Theoretical Nuclear Physics and Related Studies (ECT*), Trento (Italy), October 13 - 17, 2003. The main topics discussed at the workshop were the physics of hadronic atoms and in this context recent results in experiment and theory. Included here are the list of pa

Birgit Eberle, Andreas Ringwald, Liguo Song, Thomas J. Weiler

Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutri

Ian R. Vernon, Anne-Christine Davis

The cosmological two brane model is discussed in detail. An elegant method for deriving the generalised non-linear equations for the interbrane distance is presented. These equations are used to identify equilibrium positions of the radion, and are then linearised in order to determine the nature of these equilibrium solutions. Numerical methods are then emp

Viliam Pazma, Julius Vanko, Juraj Chovan

We present one point of contact between the standard theory of neutrino oscillations and the alternative one, in which flavor neutrinos are described by states with definite masses. We show that both theories give the same results for static neutrinos only.

E. W. Dvergsnes, P. Osland, A. A. Pankov, N. Paver

We investigate the possibility of using the center-edge asymmetry to distinguish graviton exchange from other new physics effects at hadron colliders. Specifically, we study lepton-pair production within the ADD and RS scenarios. At the Tevatron, the graviton-Z interference is the most important contribution to the center-edge asymmetry, whereas at the LHC,

Elizabeth Jenkins, Aneesh V. Manohar

We identify the quantum numbers of baryon exotics in the Quark Model, the Skyrme Model and QCD, and show that they agree for arbitrary colors and flavors. We define exoticness, E, which can be used to classify the states. The exotic baryons include the recently discovered qqqq qbar pentaquarks (E=1), as well as exotic baryons with additional q qbar pairs (E

Lev Kofman, Johannes Martin, Marco Peloso

Braneworld models in extra dimensions can be tested in laboratory by the coupling of the radion to the Standard Model fields. The identification of the radion as a canonically normalized field involves a careful General Relativity treatment: if a bulk scalar is responsible for the stabilization of the system, its fluctuations are entangled with the perturbat

V. V. Ezhela, S. B. Lugovsky, O. V. Zenin

A comprehensive as of November 2003 and evaluated data compilation on sigma_tot(e+ e- --> hadrons) was used to estimate the lowest order hadronic contribution to the muon anomalous magnetic moment. The preliminary result is a_mu(had, LO) = (699.6 +- 1.9(rad) +- 2.0(proc) +- 8.5(e+e-)) * 10^-10 The Standard Model value of the muon magnetic anomaly calculated

M. Rybczynski, Z. Wlodarczyk, G. Wilk

We argue that recent data on fluctuations observed in heavy ion collisions show non-monotonic behaviour as function of number of participants (or &#34;wounded nucleons&#34;) N_W. When interpreted in thermodynamical approach this result can be associated with a possible structure occuring in the corresponding equation of state (EoS). This in turn could be fur

Frithjof Karsch

We present results from lattice calculations on the thermodynamics of QCD at non-zero temperature and baryon chemical potential and discuss the role of resonances for the occurrence of the transition to the quark-gluon plasma in hot and dense matter. Properties of a hadronic resonance gas are compared to lattice results on the equation of state at zero as we

A. V. Gurevich, A. N. Karashtin, A. P. Chubenko, L. M. Duncan

The existence of a new phenomena - giant electron-gamma bursts is established. The bursts are generated in thunderclouds as a result of the combined action of runaway breakdown and extensive atmosphere showers (RB-EAS). The experiments were fulfilled at the Tien Shan Mountain Scientific Station using EAS-Radio installation. This specially constructed install

P. Marronetti, S. L. Shapiro

We present a new numerical scheme for solving the initial value problem for quasiequilibrium binary neutron stars allowing for arbitrary spins. We construct sequences of circular-orbit binaries of varying separation, keeping the rest mass and circulation constant along each sequence. The spin angular frequency of the stars is shown to vary along the sequence

S. Schiller, C. Laemmerzahl, H. Mueller, C. Braxmaier

It has been suggested that space-time might undergo fluctuations because of its intrinsic quantum nature. These fluctuations would pose a fundamental limit to the ability of measuring distances with arbitrary precision, beyond any limitations due to standard quantum mechanics. Laser interferometers have recently been proposed as being suited for a search for

Simone Mercuri, Giovanni Montani

This work concerns a new reformulation of quantum geometrodynamics, which allows to overcome a fundamental ambiguity contained in the canonical approach to quantum gravity: the possibility of performing a (3+1)-slicing of space-time, when the metric tensor is in a quantum regime. Our formulation provides also a procedure to solve the problems connected to th

P. Kramer, M. Lorente

The double torus provides a relativistic model for a closed 2D cosmos with topology of genus 2 and constant negative curvature. Its unfolding into an octagon extends to an octagonal tessellation of its universal covering, the hyperbolic space H^2. The tessellation is analysed with tools from hyperbolic crystallography. Actions on H^2 of groups/subgroups are

Emil Saucan

We embark in a program of studying the problem of better approximating surfaces by triangulations(triangular meshes) by considering the approximating triangulations as finite metric spaces and the target smooth surface as their Haussdorff-Gromov limit. This allows us to define in a more natural way the relevant elements, constants and invariants s.a. princip

Roberto Bagnara, Enea Zaffanella, Patricia M. Hill

Sharing, an abstract domain developed by D. Jacobs and A. Langen for the analysis of logic programs, derives useful aliasing information. It is well-known that a commonly used core of techniques, such as the integration of Sharing with freeness and linearity information, can significantly improve the precision of the analysis. However, a number of other prop

Patricia M. Hill, Enea Zaffanella, Roberto Bagnara

It is well-known that freeness and linearity information positively interact with aliasing information, allowing both the precision and the efficiency of the sharing analysis of logic programs to be improved. In this paper we present a novel combination of set-sharing with freeness and linearity information, which is characterized by an improved abstract uni

Luis A. Zepeda-Ruiz, Joerg Rottler, Seungwu Han, Graeme J. Ackland

We study diffusion of self-interstitial atoms (SIAs) in vanadium via molecular dynamics simulations. The <111>-split interstitials are observed to diffuse one-dimensionally at low temperature, but rotate into other <111> directions as the temperature is increased. The SIA diffusion is highly non-Arrhenius. At T<600 K, this behavior arises from temperature-de

Anna Delin, Erio Tosatti

We have investigated infinitely long, monostrand Pt nanowires theoretically, and found that they exhibit Hund&#39;s rule magnetism. We find a spin moment of 0.6 Bohr magnetons per atom, at the equilibrium bond length. Its magnetic moment increases with stretching. The origin of the wire magnetism is analyzed and its effect on the conductance through the wire

C. H. Lewenkopf, H. A. Weidenmueller

We study the Kondo temperature of a quantum dot embedded into one arm of an Aharonov-Bohm interferometer. The topology of a disordered or chaotic Aharanov-Bohm ring leads to a stochastic term in the scaling equation and in the renormalization procedure. As a result, the Kondo temperature displays significant fluctuations as a function of magnetic flux.

Damien Vandembroucq, Stephane Roux

The depinning of an elastic line interacting with a quenched disorder is studied for long range interactions, applicable to crack propagation or wetting. An ultrametric distance is introduced instead of the Euclidean distance, allowing for a drastic reduction of the numerical complexity of the problem. Based on large scale simulations, two to three orders of

M. Kellogg, J. P. Eisenstein, L. N. Pfeiffer, K. W. West

At total Landau level filling factor $ν_{tot}=1$ a double layer two-dimensional electron system with small interlayer separation supports a collective state possessing spontaneous interlayer phase coherence. This state exhibits the quantized Hall effect when equal electrical currents flow in parallel through the two layers. In contrast, if the currents in th

P. McHale, P. Thalmeier, P. Fulde

There is compelling evidence from inelastic-neutron-scattering and tunneling experiments that the heavy-fermion superconductor UPd$_2$Al$_3$ can be understood as a dual system consisting of magnetic excitons, arising from crystal-field-split U$^{4+}$ levels, coupled to delocalised f-electrons. We have computed the superconducting transition temperature and t

K. Rabenstein, V. A. Sverdlov, D. V. Averin

We have derived explicit non-perturbative expression for decoherence of quantum oscillations in a qubit by low-frequency noise. Decoherence strength is controlled by the noise spectral density at zero frequency while the noise correlation time $τ$ determines the time $t$ of crossover from the $1/\sqrt{t}$ to the exponential suppression of coherence. We also

Alexander P. Zhuravel, Stephen Remillard, Steven M. Anlage, Alexey V. Ustinov

Microwave resonators made from high-temperature superconducting (HTS) films are becoming increasingly commercially competitive in the market of modern communication technologies. However, unlike normal metals, the HTS device performance suffers from intrinsically nonlinear electrodynamics, resulting in harmonic generation and intermodulation (IM) distortion

M. Cozzini, L. P. Pitaevskii, S. Stringari

The elastic oscillations of the vortex lattice of a cold Bose gas (Tkachenko modes) are shown to play a crucial role in the saturation of the compressibility sum rule, as a consequence of the hybridization with the longitudinal degrees of freedom. The presence of the vortex lattice is responsible for a $q^2$ behavior of the static structure factor at small w

Igor A. Larionov

The relaxation function theory of doped two-dimensional $S=1/2$ Heisenberg antiferromagnetic (AF) system in the paramagnetic state is presented taking into account the hole subsystem as well as both the electron and AF correlations. The expression for fourth frequency moment of relaxation shape function is derived within the $t-J$ model. The presentation obe

A. I. Rahachou, I. V. Zozoulenko

We report elastic scattering theory for surface electron waves in quantum corrals defined by adatoms on the surface of noble metals. We develop a scattering-matrix technique that allows us to account for a realistic smooth potential profile of the scattering centers. Our calculations reproduce quantitatively all the experimental observations, which is in con

J. W. Brill

In recent measurements on the charge-density-wave (CDW) conductor blue bronze (K0.3MoO3), the electro-transmittance and electro-reflectance spectra were searched for intragap states that could be associated with solitons created by injection of electrons into the CDW at the current contacts [Eur. Phys. J. B 16, 295 (2000); ibid 35, 233 (2003)]. In this work,

X. N. Lin, V. A. Bondarenko, G. Cao, J. W. Brill

We have measured the specific heat of single crystals of the triple-layer Ruddlesden-Popper material, Sr4Ru3O10, grown both in an image furnace and by flux-growth. The flux grown sample has a sharp mean-field-like anomaly at the onset of magnetic order, Tc = 102 K, but a much broader anomaly, indicative of residual heterogeneity, is observed for the image fu

G. Parisi, T. Rizzo

We study the consequences of supersymmetry breaking in the computation of the number of solutions of the Thouless-Anderson-Palmer (TAP) equations. We show that Kurchan argument that proves the vanishing of the prefactor of the Bray and Moore saddle point for the total number of solutions can be extended to solutions at any given free energy. We also provide

H. Keller, T. Schneider

Granularity, anisotropy, local lattice distortions and their dependence on dopant concentration appear to be present in all cuprate superconductors, interwoven with the microscopic mechanisms responsible for superconductivity. Here we review anisotropy and penetration depth measurements to reassess the evidence for granularity, as revealed by the notorious r

Jesper Lykke Jacobsen, Jane&#39; Kondev

The competition between chain entropy and bending rigidity in compact polymers can be addressed within a lattice model introduced by P.J. Flory in 1956. It exhibits a transition between an entropy dominated disordered phase and an energetically favored crystalline phase. The nature of this order-disorder transition has been debated ever since the introductio

Marco Airoldi

In this paper we present a new methodology for option pricing. The main idea consists to represent a generic probability distribution function (PDF) via a perturbative expansion around a given, simpler, PDF (typically a gaussian function) by matching moments of increasing order. Because, as shown in literature, the pricing of path dependent European options

V. Yu. Irkhin, M. I. Katsnelson

An interplay of the Kondo scattering and exciton effects (d-f Coulomb interaction) in the intermediate valence systems and Kondo lattices is demonstrated to lead to an essential change of the scaling behavior in comparison with the standard Anderson model. In particular, a marginal regime can occur where characteristic fluctuation rate is proportional to flo

B. Delamotte, D. Mouhanna, M. Tissier

Frustrated magnets exhibit unusual critical behaviors: they display scaling laws accompanied by nonuniversal critical exponents. This suggests that these systems generically undergo very weak first order phase transitions. Moreover, the different perturbative approaches used to investigate them are in conflict and fail to correctly reproduce their behavior.

G. M. Bruun

We consider a two-component Fermi gas interacting via a Feshbach molecular state. It is shown that an important energy scale is $E_g=g^4m^3/(64π^2)$ where $g$ is the Feshbach coupling constant and $m$ the mass of the particles. Only when $E_g\gg ε_{\rm F}$ where $ε_{\rm F}$ is the Fermi energy can the gas be expected to enter a universal state in the unitari

V. I. Yukalov, A. Moura, H. Nechad

A general law of energy release is derived for stressed heterogeneous materials, being valid from the starting moment of loading till the moment of materials fracture. This law is obtained by employing the extrapolation technique of the self-similar approximation theory. Experiments are accomplished measuring the energy release for industrial composite sampl

Corrado Di Guilmi, Edoardo Gaffeo, Mauro Gallegati, Antonio Palestrini

Are expansions and recessions more likely to end as their magnitude increases? In this paper we apply parametric hazard models to investigate this issue in a sample of 16 countries from 1881 to 2000. For the total sample we find evidence of positive magnitude dependence for recessions, while for expansions we are not able to reject the null of magnitude inde

Y. Z. Zhang

We use a density matrix renormalization group method to study quantitatively the phase diagram of a one-dimensional extended Hubbard model at half-filling by investigating the correlation functions and structure factors. We confirm the existence of a novel narrow region with long-rang bond-order-wave order which is highly controversial recently between the c

Farhad H Jafarpour

The steady states of three families of one-dimensional non-equilibrium models with open boundaries, first proposed in [22], are studied using a matrix product formalism. It is shown that their associated quadratic algebras have two-dimensional representations, provided that the transition rates lie on specific manifolds of parameters . Exact expressions for

Girish S. Setlur

It is shown that gauge theories with fermions are most naturally studied via a polar decomposition of the field variable. This is the fermionic analog of the preprint cond-mat/0210673. The hope is that these two put together will enable the treatment of neutral nonrelativisitc matter composed of electrons and nuclei in a nonperturbative manner with nuclei an

A. Laeuchli, C. Honerkamp, T. M. Rice

We use exact diagonalization to determine the spectrum of reduced Hamiltonians based on renormalization group flows to strong coupling. For the half-filled two-leg Hubbard ladder we reproduce the known insulating d-Mott groundstate with spin and charge gaps. For the saddle point regions of the two-dimensional Hubbard model near half-filling we find a crossov

M. Tsuchiizu, A. Furusaki

We revisit the ground-state phase diagram of the one-dimensional half-filled extended Hubbard model with on-site (U) and nearest-neighbor (V) repulsive interactions. In the first half of the paper, using the weak-coupling renormalization-group approach (g-ology) including second-order corrections to the coupling constants, we show that bond-charge-density-wa

Marcos Lima, Wayne Hu

Cluster number counts can constrain the properties of dark energy if and only if the evolution in the relationship between observable quantities and the cluster mass can be calibrated. Next generation surveys with ~10000 clusters will have sufficient statistics to enable some degree of self-calibration. The excess variance of counts due to the clustering of

F. Thim, J. G. Hoessel, A. Saha, J. Claver

Repeated imaging observations of NGC 4395 were made with the WIYN 3.5 m and the KPNO 2.1 m telescopes. From the photometry of the resolved brighter stars in this galaxy eleven Cepheids with periods ranging between 12 and 90 days have been identified. The true distance modulus has been derived from the apparent distance moduli in g, r and i. The distance modu

Chris Mihos

Galaxy interactions expel a significant amount of stars and gas into the surrounding environment. I review the formation and evolution of the tidal debris spawned during these collisions, and describe how this evolution depends on the large scale environment in which the galaxies live. In addition to acting as a long-lived tracer of the interaction history o

Todd A. Thompson, Philip Chang, Eliot Quataert

The Kelvin-Helmholtz cooling epoch, lasting tens of seconds after the birth of a neutron star in a successful core-collapse supernova, is accompanied by a neutrino-driven wind. For magnetar-strength ($\sim10^{15}$ G) large scale surface magnetic fields, this outflow is magnetically-dominated during the entire cooling epoch.Because the strong magnetic field f

Stuart Wyithe, Abraham Loeb

The Ly-alpha absorption spectrum of the highest redshift quasars indicates that they are surrounded by giant HII regions, a few Mpc in size. The neutral gas around these HII regions should emit 21cm radiation in excess of the Cosmic Microwave Background, and enable future radio telescopes to measure the transverse extent of these HII regions. At early times,

N. J. Schurch, R. S. Warwick, R. E. Griffiths, S. M. Kahn

We present a detailed analysis of the complex soft X-ray spectrum of NGC 4151 measured by the RGS instruments aboard XMM-Newton. The XMM-Newton RGS spectra demonstrate that the soft X-ray emission is extremely rich in X-ray emission lines and radiative recombination continua (RRC), with no clear evidence for any underlying continuum emission. Line emission,

Ye-Fei Yuan, Ramesh Narayan, Martin J. Rees

The existence of black holes remains open to doubt until other conceivable options are excluded. With this motivation, we consider a model of a compact star in which most of the mass consists of dark particles of some kind, and a small fraction of the mass is in the form of ordinary nucleonic gas. The gas does not interact with the dark matter other than via

J. A. Munoz, E. E. Falco, C. S. Kochanek, B. A. McLeod

We estimate the dust extinction laws in two intermediate redshift galaxies. The dust in the lens galaxy of LBQS1009-0252, which has an estimated lens redshift of zl~0.88, appears to be similar to that of the SMC with no significant feature at 2175 A. Only if the lens galaxy is at a redshift of zl~0.3, completely inconsistent with the galaxy colors, luminosit

Mark Trodden, Sean M. Carroll

These proceedings summarize lectures that were delivered as part of the 2002 and 2003 Theoretical Advanced Study Institutes in elementary particle physics (TASI) at the University of Colorado at Boulder. They are intended to provide a pedagogical introduction to cosmology aimed at advanced graduate students in particle physics and string theory.

Krsna Dev, Marcelo Gleiser

I report on recent work concerning the existence and stability of self-gravitating spheres with anisotropic pressure. After presenting new exact solutions, Chandrasekhar&#39;s variational formalism for radial perturbations is generalized to anisotropic objects and applied to investigate their stability. It is shown that anisotropy can not only support stars

Margarita Safonova

This thesis contributes to the field of gravitational lensing (GL) and observational cosmology. We discuss the use of gravitational lensing as a tool in search of exotic objects in the Universe. In the next chapter the concordance of an alternative cosmological model with the current gravitational lensing observations is explored and also a non-minimally cou

R. Capuzzo-Dolcetta

Globular cluster systems evolve, in galaxies, due to internal and external dynamics and tidal phenomena. One of the causes of evolution, dynamical friction, is responsible for the orbital decay of massive clusters into the innermost galactic regions. It is found that these clusters are effective source of matter to feed a central galactic black hole such to

Michel Tagger, Peggy Varniere, Jerome Rodriguez, Rene Pellat

We present a scenario for the variability of the microquasar GRS 1915+105. This starts from previous works, leading to the tentative identification of the Accretion-Ejection Instability as the source of the low-frequency Quasi-Periodic Oscillation of microquasars and other accreting sources. We follow the physics of this instability: its conditions (the magn

Gerry Gilmore

Surveys of the local and distant Universe are the means to test and improve our models of galaxy formation. Substantial successes in the models are evident, while there is also considerable recent progress in identifying what remains to be learned. The key weaknesses of present models are related to merging histories, and small-scale structures, which are bo

W. R. T. Edge, M. J. Coe, J. L. Galache, A. B. Hill

We report on the analysis of 8 years of MAssive Compact Halo Objects (MACHO) data for the source RX J0520.5-6932. A regular period of 24.4 days has been confirmed, however this is manifest almost entirely in the red part of the spectrum. A major outburst, lasting approximately 200 days, was observed which increased the apparent brightness of the object by ap

W. van Straten

A mathematical framework is presented for use in the experimental determination of the polarimetric response of observatory instrumentation. Elementary principles of linear algebra are applied to model the full matrix description of the polarization measurement equation by least-squares estimation of non-linear, scalar parameters. The formalism is applied to

Michele R. Pestalozzi, Moshe Elitzur, John E. Conway, Roy S. Booth

We present an edge-on Keplerian disc model to explain the main component of the 12.2 and 6.7 GHz methanol maser emission detected toward NGC7538-IRS1 N. The brightness distribution and spectrum of the line of bright masers are successfully modeled with high amplification of background radio continuum emission along velocity coherent paths through a maser dis

R. Ramachandran, D. C. Backer, J. M. Rankin, J. M. Weisberg

We report here the discovery of a significant source of systematic error in the rotation measure determinations of pulsars. Conventional analysis of high sensitivity polarimetric observations of PSR B2016+28 display variation of the rotation measure of $\pm$15 rad m$^{-2}$ (around the mean value of -34.6 rad m$^{-2}$) across the pulse profile. Analysis of si

Solange V. Ramirez, Luisa Rebull, John Stauffer, Thomas Hearty

We present results of a Chandra observation of a field in NGC 2264. The observations were taken with the ACIS-I camera with an exposure time of 48.1 ks. We present a catalog of 263 sources, which includes X-ray luminosity, optical and infrared photometry and X-ray variability information. We found 41 variable sources, 14 of which have a flare-like light curv

Andrei Gruzinov

It is noted that inflation driven by a three form with arbitrary self coupling satisfies a consistency relation $n_S-1=2n_T$, between spectral indices of scalar and tensor cosmological perturbations. The standard consistency relation for the ratio of the amplitudes of perturbations is only valid for quadratic self coupling of the three form.

Tomoko Fujiwara, Hitoshi Yamaoka

The current system of stellar magnitudes first introduced by Hipparchus was strictly defined by Norman Robert Pogson in 1856. He based his system on Ptolemy&#39;s star catalogue `Almagest&#39;, recorded in about 137 A.D., and defined the magnitude-intensity relationship on a logarithmic scale. Stellar magnitudes observed with the naked eye recorded in seven