March 2001 arXiv papers — page 15

D. S. Gorbunov, G. G. Raffelt, D. V. Semikoz

If Ultra High Energy Cosmic Rays (UHECRs) with E>4 10^{19} eV originate from BL Lacertae at cosmological distances as suggested by recent studies, the absence of the GZK cutoff can not be reconciled with Standard-Model particle properties. Axions would escape the GZK cutoff, but even the coherent conversion and back-conversion between photons and axions in l

J. Alexander, CLEO Collaboration

We report on the observation of B-> D(*) pi+ pi- pi- pi^o decays. The branching ratios for D*+ and D*o are (1.72+/-0.14+/-0.24)% and (1.80+/-0.24+/-0.27)%, respectively. Each final state has a D* omega pi- component, with branching ratios (0.29+/-0.03+/-0.04)% and (0.45+/-0.10+/-0.07)% for the D*+ and D*o modes, respectively. We also observe B -> D omega pi-

A. Prados, J. J. Brey

The dynamical behavior of a kind of models with hierarchically constrained dynamics is investigated. The models exhibit many properties resembling real structural glasses. In particular, we focus on the study of time-dependent temperature processes. In cooling processes, a phenomenon analogous to the laboratory glass transition appears. The residual properti

C. Volpe, N. Auerbach, G. Colo, N. Van Giai

We present theoretical results on the non flux-averaged $^{208}Pb(ν_{e},e^-)^{208}Bi$ and $^{208}Pb(ν_μ,μ^-)^{208}Bi$ reaction cross sections, obtained within the charge-exchange Random-Phase-Approximation. A detailed knowledge of these cross sections is important in different contexts. In particular, it is necessary to assess the possibility of using lead a

J. Hwang, H. Noh

We consider the evolution of perturbed cosmological spacetime with multiple fluids and fields in Einstein gravity. Equations are presented in gauge-ready forms, and are presented in various forms using the curvature (Φor ϕ_χ) and isocurvature (S_{(ij)} or δϕ_{(ij)}) perturbation variables in the general background with K and Λ. We clarify the conditions for

Hideyuki Umeda, Ken'ichi Nomoto

We calculate nucleosynthesis in core-collapse explosions of massive Pop III stars, and compare the results with abundances of metal-poor halo stars to constrain the parameters of Pop III supernovae. We focus on iron-peak elements and, in particular, we try to reproduce the large [Zn/Fe] observed in extremely metal-poor stars. The interesting trends of the ob

V. N. Oraevsky, V. B. Semikoz

The relativistic kinetic equations (RKE) for lepton plasma in the presence of a strong external magnetic field are derived in Vlasov approximation. The new RKE for the electron spin distribution function includes the weak interaction with neutrinos originated by the axial vector current ($\sim c_A$) and provided by the parity nonconservation. In a polarized

A. Echeverría-Enríquez, J. Marín-Solano, M. C. Muñoz-Lecanda, N. Román-Roy

The ``time-evolution operator'' in mechanics is a powerful tool which can be geometrically defined as a vector field along the Legendre map. It has been extensively used by several authors for studying the structure and properties of the dynamical systems (mainly the non-regular ones), such as the relation between the Lagrangian and Hamiltonian forma

Navot Israeli, Daniel kandel

We propose a novel approach to continuum modeling of the dynamics of crystal surfaces. Our model follows the evolution of an ensemble of step configurations, which are consistent with the macroscopic surface profile. Contrary to the usual approach where the continuum limit is achieved when typical surface features consist of many steps, our continuum limit i

Manfred Lindner, Tommy Ohlsson, Walter Winter

Neutrino decay in vacuum has often been considered as an alternative to neutrino oscillations. Because non-zero neutrino masses imply the possibility of both neutrino decay and neutrino oscillations, we present a model-independent formal treatment of these combined scenarios. For that, we show for the example of Majoron decay that in many cases decay product

Enrico Ramirez-Ruiz, Neil Trentham, A. W. Blain

The properties of gamma-ray bursts (GRBs) and their afterglows are used to investigate the location of star formation activity through the history of the Universe. This approach is motivated by the following: (i) GRBs are thought to be associated with the deaths of massive stars and so the GRB rate ought to follow the massive star formation rate, (ii) GRBs a

P. Alberto, M. Fiolhais, B. Golli, J. Marques

The Roper resonance is described in a chiral version of the chromodielectric model as a cluster of three quarks in radial-orbital configuration (1s)$^2$(2s)$^1$, surrounded by $π$ and $σ$-meson clouds and by a chromodielectric field which assures quark dynamical confinement. Radial profiles for all fields are determined self-consistently for each baryon. Tra

K. -P. Bohnen, R. Heid, B. Renker

We present a first principles investigation of the lattice dynamics and electron-phonon coupling of the superconductor MgB_2 and the isostructural AlB_2 within the framework of density functional perturbation theory using a mixed-basis pseudopotential method. Complete phonon dispersion curves and Eliashberg functions α^2F are calculated for both systems. We

Hartmut Wachter, Michael Wohlgenannt

In this paper we present explicit formulas for the *-product on quantum spaces which are of particular importance in physics, i.e., the q-deformed Minkowski space and the q-deformed Euclidean space in 3 and 4 dimensions, respectively. Our formulas are complete and formulated using the deformation parameter q. In addition, we worked out an expansion in powers

D. I. Khomskii, K. I. Kugel

We argue that elastic interactions between ions in different valence states can play an essential role in stabilization of stripes(or 2D "sheets")in doped oxides. These interactions are in general long-range and anisotropic (attractive in certain directions and repulsive in others). This can naturally give rise to stripe-like structures in insulating

Shigenori Seki

We study orbifold group actions on locally defined fields upon M-theory branes in a three-form C-fields background. We derive some constraints from the consistency of the orbifold group actions. We show the possibility of the existence of M-theory discrete torsion for the fields on the worldvolume and discuss its features.

Y. Kazama, T. Muramatsu

As a step toward clarification of the power of supersymmetry (SUSY) in Matrix theory, a complete calculation, including all the spin effects, is performed of the effective action of a probe D-particle, moving along an arbitrary trajectory in interaction with a large number of coincident source D-particles, at one loop at order 4 in the derivative expansion.

Y. Ono, R. Bulla, A. C. Hewson, M. Potthoff

We have studied the critical behaviour of a doped Mott insulator near the metal-insulator transition for the infinite-dimensional Hubbard model using a linearized form of dynamical mean-field theory. The discontinuity in the chemical potential in the change from hole to electron doping, for $U$ larger than a critical value $U_c$, has been calculated analytic

Bing Zhang, Peter Meszaros

We investigate two high energy radiation mechanisms, the proton synchrotron and the electron inverse Compton emission, and explore their possible signatures in the broad-band spectra and in the keV to GeV light curves of gamma-ray burst afterglows. We develop a simple analytical approach, allowing also for the effects of photon-photon pair production, and ex

John F. Gunion, Stephen Mrenna

For some choices of soft SUSY--breaking parameters, the LSP is a stable neutralino, the NLSP is a chargino almost degenerate in mass with the LSP (with mass difference $\sim m_π-$few GeV), and all other sparticles are relatively heavy. We discuss the potential of a $\sqrt{s}\sim 600\gev$ $e^+e^-$ collider for studying such models.

M. D. Bowdrey, D. K. L. Oi, A. J. Short, J. A. Jones

We give a simple way of characterising the average fidelity between a unitary and a general operation on a single qubit which only involves calculating the fidelities for a few pure input states.

O. A. Olkhov

A new approach is proposed for an electromagnetic field geometrisation. We show that interacting Maxwell and Dirac fields can be considered as a single connected space-time 4-manifold. The Dirac spinors appear wihtin such approach as basic fanctions for the manifold fundamental group representation and electric and magnertic fields appear as components of a

Guo-Ping Guo, Chuan-Feng Li, Guang-Can Guo

Quantun non-demolition (QND) variables are generlized to the nonlocal ones by proposing QND measurement networks of Bell states and multi-partite GHZ states, which means that we can generate and measure them without any destruction. One of its prospective applications in the quantum authentication system of the Quantum Security Automatic Teller Machine (QSAT

Xiao-Hua Wu, HongShi Zong, Hou-Rong Pang, Fan Wang

Choosing four entangled stets to form an orthogonal and complete basis for a two-particle system, we argue that a local hidden variable model should give the probability of each entangled state if the two-particle system is described by a mixed state. Under this condition, a new Bell inequality is derived for the Werner states, and a nonlocality proof can be

C. King

It is conjectured that the Holevo capacity of a product channel Ω\otimes Φis achieved when product states are used as input. Amosov, Holevo and Werner have also conjectured that the maximal p-norm of a product channel is achieved with product input states. In this paper we establish both of these conjectures in the case that Ωis arbitrary and Φis a CQ or QC

Nguyen Ba An

We introduce a generalized class of states called K-quantum nonlinear coherent states. Each K-state has K j-components corresponding to one and the same eigenvalue. Each Kj-component can be composed of K K=1-states in a correlated manner. The introduced states are shown to be realized in the long-term behavior of the vibrational motion of an ion properly tra

Yoel Lana-Renault

An explicit expression for P-wave velocity is proposed to develop a novel tomographic technique in a spherically symmetric model of the Earth (MZY). The distribution of the P velocity structure in the mantle is determined using only 34 P- and 2 PcP-observed traveltimes. By applying a non-linear inversion, the P-residuals in the range between 0 and 100 degree

Elcio Abdalla, Bouchra Maroufi, Bertha Cuadros Melgar, Moulay Brahim Sedra

We study the problem of information propagation in brain microtubules. After considering the propagation of electromagnetic waves in a fluid of permanent electric dipoles, the problem reduces to the sine-Gordon wave equation in one space and one time dimensions. The problem of propagation of information is thus set.

S. Succi, A. Gabrielli, G. Smith, E. Kaxiras

We investigate the effects of geometrical micro-irregularities on the conversion efficiency of reactive flows in narrow channels of millimetric size. Three-dimensional simulations, based upon a Lattice-Boltzmann-Lax-Wendroff code, indicate that periodic micro-barriers may have an appreciable effect on the effective reaction efficiency of the device. Once ext

J. Carbonell

The recent calculation of the four nucleon continuum spectrum are reviewed. Faddeev-Yakubovsky equations in configuration space have been solved for the four nucleon system with special interest in their scattering states. We present results concerning the structure of the first $^4$He, scattering states in different (T,S) channels including the first inelat

J. Carbonell

The Faddeev-Yakubovsky equations in configuration space have been solved for the four nucleon system with special interest in their scattering states. We present results concerning the structure of the first $^4$He, scattering states in different (T,S) channels including the first inelatic threshold N+3N$\to$NN+NN and the n-t cross section using realistic po

V. E. Oberacker, A. S. Umar, J. Chen, E. Teran

We have developed a new HFB code that specifically addresses nuclear structure physics near the driplines. The HFB equations are solved on a two-dimensional lattice for axially symmetric even-even nuclei using B-Spline techniques. The quasiparticle energy spectrum is obtained by direct diagonalization of the HFB lattice Hamiltonian with LAPACK. The energy sp

S. Sakakihara, Y. Tanaka

Charge radii of Sn, Ba, Yb, and Pb isotopes are calculated within Hartree-Fock-Bogoliubov theory with a Skyrme force and a density-dependent delta-force pairing. We investigate mean field effects of the pairing upon odd-even staggering of isotope shifts. HFB equations are solved in the canonical basis. Odd nuclei are treated in the blocking approximation.

C. Fuchs, Amand Faessler, S. El-Basaouny, E. Zabrodin

The dependence of $K^+$ production on the nuclear equation of state is investigated in heavy ion collisions. An increase of the excitation function of $K^+$ multiplicities obtained in heavy ($Au+Au$) over light ($C+C$) systems when going far below threshold which has been observed by the KaoS Collaboration strongly favours a soft equation of state. This obse

M. M. Pavan, J. T. Brack, F. Duncan, A. Feltham

A precision measurement of absolute pi+p and pi-p elastic differential cross sections at incident pion laboratory kinetic energies from T_pi= 141.15 to 267.3 MeV is described. Data were obtained detecting the scattered pion and recoil proton in coincidence at 12 laboratory pion angles from 55 to 155 degrees for pi+p, and six angles from 60 to 155 degrees for

Steve K. Lamoreaux

The working notes which led to the physics demonstration ultracold neutron source that has been operated at Los Alamos are transcribed here. In addition to the transcribed notes, included are a Prologue that describes the path that led to be basic idea, and an Epilogue that describes some of the discoveries in the implementation of the idea.

A. Abd El-Hady, A. Y. Abul-Magd, M. H. Simbel

We study the effect of gradual symmetry breaking in a non-integrable system on the level fluctuation statistics. We consider the case when the symmetry is represented by a quantum number that takes one of two possible values, so that the unperturbed system has a spectrum composed of two independent sequences. When symmetry-breaking perturbation is represente

Ko van der Weele, Devaraj van der Meer, Michel Versluis, Detlef Lohse

Granular material is vibro-fluidized in N=2 and N=3 connected compartments, respectively. For sufficiently strong shaking the granular gas is equi-partitioned, but if the shaking intensity is lowered, the gas clusters in one compartment. The phase transition towards the clustered state is of 2nd order for N=2 and of 1st order for N=3. In particular, the latt

Devaraj van der Meer, Ko van der Weele, Detlef Lohse

The bifurcation diagram for a vibro-fluidized granular gas in N connected compartments is constructed and discussed. At vigorous driving, the uniform distribution (in which the gas is equi-partitioned over the compartments) is stable. But when the driving intensity is decreased this uniform distribution becomes unstable and gives way to a clustered state. Fo

Florian Girelli, Thomas Krajewski, Pierre Martinetti

In this talk, we show how the Connes-Kreimer Hopf algebra morphism can be extended when taking into account the wave-function renormalization. This leads us to a semi-direct product of invertible power series by formal diffeomorphisms.

Derong Qiu, Xianke Zhang

Consider elliptic curves $ E=E_σ: y^2 = x (x+σp) (x+σq), $ where$ σ=\pm 1, $ $p$ and $ q$ are prime numbers with $p+2=q$. (1) The Selmer groups $ S^{(2)}(E/{\mathbf{Q}}), S^{(ϕ)}(E/{\mathbf{Q})}$, and $\ S^{(\hatϕ)}(E/{\mathbf{Q})} $ are explicitly determined, e.g., $\ S^{(2)}(E_{+1}/{\mathbf{Q}})= $ $({\mathbf{Z}}/2{\mathbf{Z}})^2; $ $ ({\mathbf{Z}}/2{\math

Derong Qiu, Xianke Zhang

$L-$series attached to two classical families of elliptic curves with complex multiplications are studied over number fields, formulae for their special values at $s=1, $ bound of the values, and criterion of reaching the bound are given. Let $ E_1: y^{2}=x^{3}-D_1 x $ be elliptic curves over the Gaussian field $K=\Q(\sqrt{-1}), $ with $ D_1 =π_{1} ... π_{n}

Greg W. Anderson

We say that a group is {\em almost abelian} if every commutator is central and squares to the identity. Now let $G$ be the Galois group of the algebraic closure of the field $\QQ$ of rational numbers in the field of complex numbers. Let $G^{\ab+ε}$ be the quotient of $G$ universal for homomorphisms to almost abelian profinite groups and let $\QQ^{\ab+ε}/\QQ$

Stephen J. Wright

We show that the effects of finite-precision arithmetic in forming and solving the linear system that arises at each iteration of primal-dual interior-point algorithms for nonlinear programming are benign, provided that the iterates satisfy centrality and feasibility conditions of the type usually associated with path-following methods. When we replace the s

M. Fernandez-Lebron, L. Narvaez-Macarro

Let $k$ be a perfect field of characteristic $p>0$, $k(t)_{per}$ the perfect closure of $k(t)$ and $A$ a $k$-algebra. We characterize whether the ring $A\otimes_k k(t)_{per}$ is noetherian or not. As a consequence, we prove that the ring $A\otimes_k k(t)_{per}$ is noetherian when $A$ is the ring of formal power series in $n$ indeterminates over $k$.

Welleda Baldoni-Silva, Michèle Vergne

In these notes, we explain residue formulae for volumes of convex polytopes, and for Ehrahrt polynomials based on the notion of total residue. We apply this method to the computation of the volume of the Chan-Robbins polytope. The final computation is based on a total residue formula for the system $A_n$, similar to Morris identity. For flow polytopes, a for

C. Duval, V. Ovsienko

We extend projectively equivariant quantization and symbol calculus to symbols of pseudo-differential operators. An explicit expression in terms of hypergeometric functions with noncommutative arguments is given. Some examples are worked out, one of them yielding a quantum length element on $S^3$.

N. Ginoux, B. Morel

We give lower bounds for the eigenvalues of the submanifold Dirac operator in terms of intrinsic and extrinsic curvature expressions. We also show that the limiting cases give rise to a class generalizing that of Killing spinors. We conclude by translating these results in terms of intrinsic twisted Dirac operators.

J. Denef, F. Loeser

We prove several results on monodromies associated to Macdonald integrals, that were used in our previous work on the finite field analogue of a conjecture of Macdonald. We also give a new proof of our formula expressing recursively the zeta function of the local monodromy at the origin of the discriminant of a finite Coxeter group in terms of the degrees of

D. Castro, J. L. Montana, L. M. Pardo, J. San Martin

We show that rational data of bounded input length are uniformly distributed with respect to condition numbers of numerical analysis. We deal both with condition numbers of Linear Algebra and with condition numbers for systems of multivariate polynomial equations. For instance, we show that for any $w>1$ and for any $n\times n$ rational matrix $M$ of bit len

Shun-Jen Cheng, Weiqiang Wang

We classify anti-involutions of Lie superalgebra $\hsd$ preserving the principal gradation, where $\hsd$ is the central extension of the Lie superalgebra of differential operators on the super circle $S^{1|1}$. We clarify the relations between the corresponding subalgebras fixed by these anti-involutions and subalgebras of $\hat{gl}_{\infty|\infty}$ of types

D. Schuetz

We consider the closed orbit structure of generic gradient flows of Morse closed 1-forms. The torsion of a chain homotopy equivalence between the Novikov complex and the completed simplicial chain complex of the universal cover detects the eta function of the flow. We extend this result to arbitrary Morse closed 1-forms. The case of rational forms was consid

Elias Gravanis, Nick E. Mavromatos

We study a four-dimensional spacetime induced by the recoil of a D(irichlet)-particle, embeded in it, due to scattering by a moving string. The induced spacetime has curvature only up to a radius that depends on the energy of the incident string. Outside that region (`bubble') the spacetime is matched with the Minkowski spacetime. The interior of the bub

Shin-Ichiro Kuroki, Keiichi Morikawa, Takuya Morozumi

We derive an effective Lagrangian for meson fields. This is done in the light-cone gauge for two-dimensional large-N_c QCD by using the bilocal auxiliary field method. The auxiliary fields are bilocal on light-cone space and their Fourier transformation determines the parton momentum distribution. As the first test of our method, the 't Hooft equation is

Cihan Saclioglu

We discuss the possible relevance of some recent mathematical results and techniques on four-manifolds to physics. We first suggest that the existence of uncountably many R^4's with non-equivalent smooth structures, a mathematical phenomenon unique to four dimensions, may be responsible for the observed four-dimensionality of spacetime. We then point out

A. Chuvakin, J. Smith

A new code for the scale evolution of modified-minimal-subtraction-scheme parton densities is described. Through next-to-leading order the program uses exact splitting functions. In next-to-next-to-leading order approximate splitting functions are used. For efficiency the program includes analytical results for the evaluation of the weights required for the

Matt Dobbs

A method for incorporating information from next-to-leading order QCD matrix elements for hadronic diboson production into showering event generators is presented. In the hard central region (high jet transverse momentum) where perturbative QCD is reliable, events are sampled according to the first order tree level matrix element. In the soft and collinear r

F. E. Close, A. Kirk

Lattice QCD predictions have motivated several recent studies of the mixing between the predicted JPC = 0++ glueball and a qqbar nonet in the 1.3 to 1.7 GeV region. We show that results from apparently different approaches have some common features, explain why this is so and abstract general conclusions. We place particular emphasis on the flavour dependent

A. I. L'vov, S. Scherer, B. Pasquini, C. Unkmeir

We present a phenomenological discussion of spin-independent, generalized dipole polarizabilities of hadrons entering the virtual Compton scattering process gamma* h -> gamma h. We introduce a new method of obtaining a tensor basis with appropriate Lorentz-invariant amplitudes which are free from kinematical singularities and constraints. We then motivate a

V. V. Kiselev, A. K. Likhoded

We consider general physical characteristics of doubly heavy baryons: the spectroscopy in the framework of potential approach and sum rules of QCD, mechanisms of production in various interactions on the basis of fragmentation model with account of preasymptotic corrections caused by higher twists over the transverse momentum of baryon, inclusive decays and

R. Ouyed, F. Sannino

We construct the effective Lagrangian describing the light glueballs associated with the unbroken and confining SU(2) color subgroup for the 2 flavor superconductive phase of QCD. This Lagrangian constitutes a key ingredient for understanding the non perturbative physics of 2 flavor color superconductivity. We estimate the two photon decay process of the lig

R. Kenna, J. C. Sexton

The nature of the phase transition in the lattice Gross-Neveu model with Wilson fermions is investigated using a new analytical technique. This involves a new type of weak coupling expansion which focuses on the partition function zeroes of the model. Its application to the single flavour Gross-Neveu model yields a phase diagram whose structure is consistent

Rajiv V. Gavai, Sourendu Gupta

We report first results on the strange quark number susceptibility, chi_s, over a large range of temperatures, mainly in the plasma phase of QCD. Chi_s jumps across the phase transition temperature, T_c, and grows rapidly with temperature above but close to T_c. For all quark masses and susceptibilities in the entire temperature range studied, we found signi

The DELPHI Collaboration, P. Abreu

The DELPHI detector at LEP has collected 54 pb^{-1} of data at a centre-of-mass energy around 183 GeV during 1997, 158 pb^{-1} around 189 GeV during 1998, and 187 pb^{-1} between 192 and 200 GeV during 1999. These data were used to measure the average charged particle multiplicity in e+e- -> b bbar events, <n>_{bb}, and the difference delta_{bl} between <n>_

The DELPHI Collaboration, P. Abreu

Production of Sigma- and Lambda(1520) in hadronic Z decays has been measured using the DELPHI detector at LEP. The Sigma- is directly reconstructed as a charged track in the DELPHI microvertex detector and is identified by its Sigma -> n pi decay leading to a kink between the Sigma- and pi-track. The reconstruction of the Lambda(1520) resonance relies strong

J. Damgov, V. Genchev, S. Cht. Mavrodiev

CMS calorimeter energy calibration was done in the full CMS simulated geometry for the pseudorapidity region eta = 0. The samples of single pion events were generated with a set of incident energies from 10 GeV to 3 TeV. The analysis of the simulated data shows that standard calibration using just sampling coefficients for calorimeter parts with different sa

Bernard S. Kay

Several situations of physical importance may be modelled by linear quantum fields propagating in fixed spacetime-dependent classical background fields. For example, the quantum Dirac field in a strong and/or time-dependent external electromagnetic field accounts for the creation of electron-positron pairs out of the vacuum. Also, the theory of linear quantu

J. N. Butterfield

I discuss J. Barbour&#39;s Machian theories of dynamics, and his proposal that a Machian perspective enables one to solve the problem of time in quantum geometrodynamics (by saying that there is no time). I concentrate on his recent book &#39;The End of Time&#39; (1999).

K. Glampedakis, N. Andersson

We study the late-time behaviour of a dynamically perturbed rapidly rotating black hole. Considering an extreme Kerr black hole, we show that the large number of virtually undamped quasinormal modes (that exist for nonzero values of the azimuthal eigenvalue m) combine in such a way that the field (as observed at infinity) oscillates with an amplitude that de

Diego Pavon, Roberto A. Sussman

We consider the Lema\^ıtre-Tolman-Bondi metric with an inhomogeneous viscous fluid source satisfying the equation of state of an interactive mixture of radiation and matter. Assuming conditions prior to the decoupling era, we apply Extended Irreversible Thermodynamcs (EIT) to this mixture. Using the full transport equation of EIT we show that the relaxation

Claus Lämmerzahl, Mark P. Haugan

Recent proposals for improved optical tests of Special Relativity have renewed interest in the interpretation of such tests. In this paper we discuss the interpretation of modern realizations of the Michelson-Morley experiment in the context of a new model of electrodynamics featuring a vector-valued photon mass. This model is gauge invariant, unlike massive

Vladimir S. Mashkevich

Current physics is faced with the fundamental problem of unifying quantum theory and general relativity, which would have resulted in quantum gravity. The main effort to construct the latter has been bent on quantizing spacetime structure, in particular metric. Meanwhile, taking account of the indeterministic aspect of the quantum description of matter, whic

Wolfhard Janke, Ralph Kenna

We discuss a numerical analysis employing the density of partition function zeroes which permits effective distinction between phase transitions of first and second order, elucidates crossover between such phase transitions and gives a new way to measure their strengths in the form of latent heat and critical exponents. Application to a number of models demo

W. Janke, R. Kenna

The Ising model in two dimensions with the special boundary conditions of Brascamp and Kunz is analysed. Leading and sub-dominant scaling behaviour of the Fisher zeroes are determined exactly. The finite-size scaling, with corrections, of the specific heat is determined both at the critical and pseudocritical points. The shift exponents associated with scali

C. P. Moca, E. Macocian

We performed a self-consistent calculation of the transport properties of a d-wave superconductor. We used for calculations the T-matrix approximation. The coresponding equations were evaluated numerically directly on the real frequecy axis. We studied the ab-plane charge dynamics in the coherent limit. For the c-axis charge dynamics, we considered both, the

D. Reith, B. Mueller, F. Mueller-Plathe, S. Wiegand

This work adresses the question of the scaling behaviour of polyelectrolytes in solution for a realistic prototype: We show results of a combined experimental (light scattering) and theoretical (computer simulations) investigation of structural properties of poly (acrylic acid) (PAA). Experimentally, we determined the molecular weight (M_W) and the hydrodyna

Eddy Timmermans, Kyoko Furuya, Peter W. Milonni, Arthur K. Kerman

We show that composite fermi/bose superfluids can be created in cold-atom traps by employing a Feshbach resonance or coherent photoassociation. The bosonic molecular condensate created in this way implies a new fermion pairing mechanism associated with the exchange of fermion pairs between the molecular condensate and an atomic fermion superfluid. We predict

U. Lundin, I. Sandalov, O. Eriksson, B. Johansson

The mechanism of f-electron delocalization is investigated within the multi-orbital Anderson lattice model by means of diagrammatic perturbation theory from the atomic limit. The derived equations couple the intra-atomic transition energies, their spectral weights and population numbers of the many-electron states. Its self-consistent solution for praseodymi

Urban Lundin, Olle Eriksson

It is demonstrated that the commonly applied self interaction correction (SIC) used in density functional theory does not remove all self interaction. We present as an alternative a novel method which, by construction, is totally free from self interaction. The method has the correct asymptotic 1/r dependence. We apply the new theory to localized $f$-electro

U. Lundin, I. Sandalov, O. Eriksson, B. Johansson

We show that incorporation of strong electron correlations into the Kohn-Sham scheme of band structure calculations leads to a modification of the standard model of the lanthanides and that this procedure removes the existing discrepancy between theory and experiment concerning the ground state properties. Within the picture suggested, part of the upper Hubb

Alexis Lefevre, Laurent J. Lewis, Ludvik Martinu, Michael R. Wertheimer

Classical molecular-dynamics simulations have been carried out to investigate densification mechanisms in silicon dioxide thin films deposited on an amorphous silica surface, according to a simplified ion-beam assisted deposition (IBAD) scenario. We compare the structures resulting from the deposition of near-thermal (1 eV) SiO$_{2}$ particles to those obtai

D. J. J. Farnell, K. A. Gernoth, R. F. Bishop

The coupled cluster method (CCM) is applied to the spin-one anisotropic Heisenberg antiferromagnet (HAF) on the square lattice at zero temperature using a new high-order CCM ground-state formalism for general quantum spin number ($s \ge 1/2$). The results presented constitute the first such application of this new formalism, and they are shown to be among th

Joerg Rissler, Florian Gebhard, Peter Schwerdtfeger, Heinz Baessler

Ground state properties and excited states of ladder-type paraphenylene oligomers are calculated applying semiempirical methods for up to eleven phenylene rings. The results are in qualitative agreement with experimental data. A new scheme to interpret the excited states is developed which reveals the excitonic nature of the excited states. The electron-hole

Jian-Sheng Wang

The basic problem in equilibrium statistical mechanics is to compute phase space average, in which Monte Carlo method plays a very important role. We begin with a review of nonlocal algorithms for Markov chain Monte Carlo simulation in statistical physics. We discuss their advantages, applications, and some challenge problems which are still awaiting for bet

Nobuo Furukawa, Yukitoshi Motome, Hisaho Nakata

A new algorithm for Monte Carlo calculation of the double exchange model is studied. The algorithm is commonly applicable to wide classes of strongly correlated electron systems which involve itinerant electrons coupled with thermodynamically fluctuating fields. Using moment expansions of the density of states with Chebyshev polynomials, the algorithm provid

Cesar R. de Oliveira, Giancarlo Q. Pellegrino

It is reported a combined numerical approach to study the localization properties of the one-dimensional tight-binding model with potential modulated along the prime numbers. A localization-delocalization transition was found as function of the potential intensity; it is also argued that there are delocalized states for any value of the potential intensity.

A. M. Hopkins, A. J. Connolly, D. B. Haarsma, L. E. Cram

Different wavelength regimes and methods for estimating the space density of the star-formation rate (SFR) result in discrepant values. While it is recognised that ultra-violet (UV) and H-alpha emission line data must be corrected for the effects of extinction, the magnitude of the required correction is uncertain. Even when these corrections are made there

C. L. Carilli, F. Bertoldi, M. Rupen, Xiaohui Fan

We present observations at 250 GHz (1.2 mm), 43 GHz, and 1.4 GHz of a sample of 41 QSOs at z > 3.7 found in the Sloan Digital Sky Survey. We detect 16 sources with a 250 GHz flux density greater than 1.4 mJy. The combination of centimeter and millimeter wavelength observations indicates that the 250 GHz emission is most likely thermal dust emission. Assuming

Paolo Padoan, Sungeun Kim, Alyssa Goodman, Lister Staveley--Smith

We propose a new method to measure and map the gas scale height of nearby disk galaxies. This method is applied successfully to the Australia Telescope Compact Array interferometric HI survey of the Large Magellanic Cloud (LMC); it could also be applied to a significant number of nearby disk galaxies, thanks to the next generation of interferometric faciliti

V. La Parola, G. Peres, G. Fabbiano, D. W. Kim

The source X-9 was discovered with the {\it Einstein Observatory} in the field of M81, and is located in the dwarf galaxy Holmberg IX. X-9 has a 0.2-4.0 keV luminosity of $\sim 5.5\times 10^{39}$ ergs~s$^{-1}$, if it is at the same distance as Holmberg IX (3.4 Mpc). This luminosity is above the Eddington luminosity of a 1~$M_{\odot}$ compact accreting object

J. E. Bjorkman, Kenneth Wood

We describe a general radiative equilibrium and temperature correction procedure for use in Monte Carlo radiation transfer codes with sources of temperature-independent opacity, such as astrophysical dust. The technique utilizes the fact that Monte Carlo simulations track individual photon packets, so we may easily determine where their energy is absorbed. W

Sergei Sazonov, Rashid Sunyaev

Measured values of the brightness temperature of low-frequency synchrotron radiation emitted by powerful extragalactic sources reach 10^11--10^12 K. If some amount of nonrelativistic ionized gas is present within such sources, it should be heated as a result of induced Compton scattering of the radiation. If this heating is counteracted by cooling due to inv

H. Liszt, R. Lucas

Using the Plateau de Bure interferometer, we observed the 3mm absorption lines of CN, HCN and HNC from some of the diffuse clouds which lie toward our well-studied sample of compact extragalactic mm-wave continuum sources. The column densities of these species all vary by a factor of about fifty and are prominent in only a limited subset of the clouds seen i

H. Liszt

Collisional excitation of the 21cm HI hyperfine transition is not strong enough to thermalize it in warm neutral (``intercloud&#39;&#39;) interstellar gas, which we show by simultaneously solving the equations of ionization and collisional equilibrium under typical conditions. Coupling of the 21cm excitation temperature and local gas motions may be establish

Haralambi Markov, Nedka Spassova, Plamen Baev

We present stellar photometry in the UBV passbands for the globular cluster M5 = NGC5904. The observations, short-exposured photographic plates and CCD frames, were obtained in the RC-focus of the 2m telescope of the Natl. Astron. Obs. &#39;Rozhen&#39;. All stars in an annulus with radius 1 < r < 5.5 arcmin were measured. We show that the UV CMDs describe di

Arne Henden, Ulisse Munari

We present accurate and deep UBVRI photometric sequences for an additional 20 symbiotic stars. As for the 20 targets of Paper I, the sequences extend over wide brightness and color ranges, and are suited to cover both quiescence and outburst phases. The sequences are intended to assist both present time photometry as well as measurement of photographic plate

D. L. Clements, F-X. Desert, A. Franceschini

We present the first results of our followup programme of optical imaging and spectroscopy of a deep 12 micron survey conducted with the ISO satellite (Clements et al. 1999). We find that the objects are typically of fairly low redshift (z ~ 0.1-0.2), but with a tail that extends to high redshifts. The highest redshift object is a previously unknown quasar a

V. M. Woolf, R. Aznar Cuadrado, G. Pandey, C. Simon Jeffery

We report a photometric and spectroscopic study of the hot extreme helium star LSS 5121. We found photometric variability, but no period was evident in its periodogram. This is consistent with the previous proposal, based on spectral line variations, that LSS 5121 is a non-radial pulsator similar to other hot extreme helium stars.

James S. Dunlop

I review our knowledge of the properties of the host galaxies of radio-loud and radio-quiet quasars, both in comparison to each other and in the context of the general galaxy population. It is now clear that the hosts of radio-loud and radio-quiet quasars with M_V < -23.5 are virtually all massive elliptical galaxies. The masses of these spheroids are as exp

R. A. Jansen, P. Jakobsen

The evolution of the shape and size of the ejecta of SN 1987A is analyzed over a period of ~ 8 years based on HST images and spectra taken between 1278 and 4336 days after the supernova outburst. We combine both proprietary and archival HST data obtained with the FOC, WFPC2 and STIS. The low resolution near-UV prism FOC spectrum obtained at day 3043 has not