May 2003 arXiv papers — page 6

Burc Gokden

In this paper we briefly define distance vector routing algorithms, their advantages and possible drawbacks. On these possible drawbacks, currently widely used methods split horizon and poisoned reverse are defined and compared. The count to infinity problem is specified and it is classified to be a halting problem and a proposition stating that entangled st

B. Nagorny, Th. Elsaesser, A. Hemmerich

We report on collective non-linear dynamics in an optical lattice formed inside a high finesse ring cavity in a so far unexplored regime, where the light shift per photon times the number of trapped atoms exceeds the cavity resonance linewidth. We observe bistability and self-induced squeezing oscillations resulting from the retro-action of the atoms upon th

Sabine Kreidl, Gebhard Gruebl, Hans G. Embacher

The computation of detection probabilities and arrival time distributions within Bohmian mechanics in general needs the explicit knowledge of a relevant sample of trajectories. Here it is shown how for one-dimensional systems and rigid inertial detectors these quantities can be computed without calculating any trajectories. An expression in terms of the wave

B. Meulenbroek, A. Rocco, U. Ebert

Spontaneous branching of discharge channels is frequently observed, but not well understood. We recently proposed a new branching mechanism based on simulations of a simple continuous discharge model in high fields. We here present analytical results for such streamers in the Lozansky-Firsov limit where they can be modelled as moving equipotential ionization

D. Bazeia, J. Menezes, R. Menezes

We investigate the presence of defects in systems described by real scalar field in (D,1) spacetime dimensions. We show that when the potential assumes specific form, there are models which support stable global defects for D arbitrary. We also show how to find first-order differential equations that solve the equations of motion, and how to solve models in

Gianluca Bande, Amine Hadjar

We introduce a new geometric structure on differentiable manifolds. A \textit{Contact} \textit{Pair}on a manifold $M$ is a pair $(α,η) $ of Pfaffian forms of constant classes $2k+1$ and $2h+1$ respectively such that $α\wedge dα^{k}\wedgeη\wedge dη^{h}$ is a volume form. Both forms have a characteristic foliation whose leaves are contact manifolds. These foli

John Fredsted

The paper has been withdrawn by the author, due to it being fundamentally flawed. The author apologizes for any inconvenience it may have caused.

A. Rabhi

Self-consistent random phase approximation (SCRPA) is applied to the exactly solvable model with fermion boson coupling proposed by Schütte and Da-Providencia. Very encouraging results in comparison with the exact solution of the model for various observables are obtained. The transition from the normal phase to the phase with a spontaneously broken symmetry

M. A. Thompson, G. H. Macdonald

We have carried out a molecular line survey of the candidate massive protostar IRAS 23385+6053, covering a 27.2 GHz frequency range in the 330--360 GHz atmospheric window. We detected 27 lines originating from a total of 11 species.Over a third of the identified molecular lines are from the asymmetric top molecule methanol (CH$_{3}$OH). We did not detect any

Matt Broadhead, John McDonald

It has been shown that hybrid inflation may end with the formation of non-topological solitons of inflaton field. As a first step towards a fully realistic picture of the post-inflation era and reheating in supersymmetric hybrid inflation models, we study the classical scalar field equations of a supersymmetric hybrid inflation model using a semi-analytical

Kenzo Inoue, Nao-aki Yamashita

A new mechanism is proposed to explain neutrino masses and their mixing via SU(1,1) horizontal symmetry breaking. Based on this mechanism smallness of neutrino masses is naturally realized and inverted hierarchical spectrum with large mixing is given.

Peter Fiebig

We show that the structure of blocks outside the critical hyperplanes of category O over any symmetrizable Kac-Moody algebra depends only on the corresponding integral Weyl group and its action on the parameters of the Verma modules by giving a combinatorial description of the projective objects. As an application we derive the Kazhdan-Lusztig conjecture for

Shun-ichiro Koh

Gas-liquid condensation (GLC) in an attractive Bose gas is studied on the basis of statistical mechanics. Using some results in combinatorial mathematics, the following are derived: (1) With decreasing temperature, the Bose-statistical coherence grows in the many-body wave function, which gives rise to the divergence of the grand partition function prior to

J. S. Rozowsky, R. R. Volkas, K. C. Wali

We study kink (domain wall) solutions in a model consisting of two complex scalar fields coupled to two independent Abelian gauge fields in a Lagrangian that has $U(1)\times U(1)$ gauge plus $\mathbb{Z}_2$ discrete symmetry. We find consistent solutions such that while the U(1) symmetries of the fields are preserved while in their respective vacua, they are

Masayuki Asaoka

We give complete classification of C^2-regular and non-degenerate projectively Anosov flows on three dimensional manifolds. More precisely, we prove that such a flow on a connected manifold must be either an Anosov flow or represented as a finite union of $T^2 \times [0,1]$-models.

J. D. Franson, T. B. Pittman, J. P. Dowling

This paper has been withdrawn by the authors due to an error first noted by M. Lukin.

A. Messikh, Z. Ficek, M. R. B. Wahiddin

We show that two definitions of spin squeezing extensively used in the literature [M. Kitagawa and M. Ueda, Phys. Rev. A {\bf 47}, 5138 (1993) and D.J. Wineland {\it et al.}, Phys. Rev. A {\bf 50}, 67 (1994)] give different predictions of entanglement in the two-atom Dicke system. We analyze differences between the definitions and show that the Kitagawa and

A. Kuzmich, W. P. Bowen, A. D. Boozer, A. Boca

Quantum information science attempts to exploit capabilities from the quantum realm to accomplish tasks that are otherwise impossible in the classical domain [1]. Although sufficient conditions have been formulated for the physical resources required to achieve quantum computation and communication [2], there is an evolving understanding of the power of quan

Francesco Ticozzi, Augusto Ferrante, Michele Pavon

Robust open-loop steering of a finite-dimensional quantum system is a central problem in a growing number of applications of information engineering. In the present paper, we reformulate the problem in the classical control-theoretic setting, and provide a precise definition of {\em robustness} of the control strategy. We then discuss and compare some signif

H. H. Erbil

By using a simple procedure the general solution of the time-independent radial Schrodinger Equation for spherical symmetric potentials was made without making any approximation. The wave functions are always periodic. It appears two diffucilties: one of them is the solution of the equation E= U(r), where E and U(r) are the total an effective potential energ

D. Asthagiri, Lawrence R. Pratt, J. D. Kress, M. A. Gomez

The HO$^-$(aq) ion participates in myriad aqueous phase chemical processes of biological and chemical interest. A molecularly valid description of its hydration state, currently poorly understood, is a natural prerequisite to modeling chemical transformations involving HO$^-$(aq). Here it is shown that the statistical mechanical quasi-chemical theory of solu

A. I. Rahachou, I. V. Zozoulenko

We perform numerical studies of the effect of sidewall imperfections on the resonant state broadening of the optical microdisk cavities for lasing applications. We demonstrate that even small edge roughness causes a drastic degradation of high-Q whispering gallery (WG) mode resonances reducing their Q-values by many orders of magnitude. At the same time, low

B. F. Bayman, F. Zardi

We present a new method of obtaining time-dependent matrix elements of the electromagnetic pulse produced by a highly-relativistic projectile. These matrix elements are used in a coupled-channel calculation to predict the cross-sections for population of 1- and 2-phonon states of the giant dipole resonance. Comparisons are made with the predictions of the lo

R. J. Fries, B. Muller, C. Nonaka, S. A. Bass

We show that hadron production in relativistic heavy ion collisions at transverse momenta larger than 2 GeV/c can be explained by the competition of two different hadronization mechanisms. Above 5 GeV/c hadron production can be described by fragmentation of partons that are created perturbatively. Below 5 GeV/c recombination of partons from the dense and hot

A. Sulaksono, T. Buervenich, J. A. Maruhn, P. -G. Reinhard

We relate the relativistic finite range mean-field model (RMF-FR) to the point-coupling variant and compare the nonlinear density dependence. From this, the effective Hamiltonian of the nonlinear point-coupling model in the nonrelativistic limit is derived. Different from the nonrelativistic models, the nonlinearity in the relativistic models automatically y

Henryk Fukś

We demonstrate that the concept of a conservation law can be naturally extended from deterministic to probabilistic cellular automata (PCA) rules. The local function for conservative PCA must satisfy conditions analogous to conservation conditions for deterministic cellular automata. Conservation condition for PCA can also be written in the form of a current

Richard Kenyon, Jean-Marc Schlenker

Given a finite or infinite planar graph all of whose faces have degree 4, we study embeddings in the plane in which all edges have length 1, that is, in which every face is a rhombus. We give a necessary and sufficient condition for the existence of such an embedding, as well as a description of the set of all such embeddings.

Ola Bratteli, Palle E. T. Jorgensen, Vasyl Ostrovskyi

Let O_d be the Cuntz algebra on generators S_1,...,S_d, 2 \leq d < \infty, and let D_d \subset O_d be the abelian subalgebra generated by monomials S_αS_α^* =S_{α_{1}}...S_{α_{k}}S_{α_{k}}^*...S_{α_{1}}^* where α=(α_1...α_k) ranges over all multi-indices formed from {1,...,d}. In any representation of O_d, D_d may be simultaneously diagonalized. Using S_i(S_

Marius Junge

Using free random varaibles we find an embedding of the operator space $OH$ in the predual of a von Neumann algebra. The properties of this embedding allow us to determined the projection constant of $OH_n$, i.e. there exists a projection $P:B(\ell_2)\to OH_n$ whose completely bounded norm behaves as n^{1/2}/(1+ln n)^{1/2}. According to recent results of Pis

A. N. Zubkov

We introduce a new concept of mixed representations of quivers that is a generalization of ordinary representations of quivers and orthogonal (symplectic) representations of symmetric quivers introduced recently by Derksen and Weyman. We describe the generating invariants of mixed representations of quivers (First Fundamental Theorem) and prove additional re

Erik Koelink

The second order hypergeometric q-difference operator is studied for the value c=-q. For certain parameter regimes the corresponding recurrence relation can be related to a symmetric operator on the Hilbert space l^2(Z). The operator has deficiency indices (1,1) and we describe as explicitly as possible the spectral resolutions of the self-adjoint extensions

Matthias Aschenbrenner, Wai-Yan Pong

We study the set of monomial ideals in a polynomial ring as an ordered set, with the ordering given by reverse inclusion. We give a short proof of the fact that every antichain of monomial ideals is finite. Then we investigate ordinal invariants for the complexity of this ordered set. In particular, we give an interpretation of the height function in terms o

Donald Mills

We demonstrate, using character sum arguments, the existence of primitive polynomials of degree n over a finite field GF(q) with the coefficients for x^(n-1), x^(n-2), and x^(n-3) prescribed, so long as char(GF(q)) is at least 5 and n is at least 9. The cases n=7, 8 are also considered.

Patrick Popescu-Pampu

We associate to any irreducible germ S of complex quasi-ordinary hypersurface an analytically invariant semigroup. We deduce a direct proof (without passing through their embedded topological invariance) of the analytical invariance of the normalized characteristic exponents. These exponents generalize the generic Newton-Puiseux exponents of plane curves. In

Klaus-Detlef Kuersten, Elmar Wagner

An operator theoretic approach to invariant integration theory on non-compact quantum spaces is introduced on the example of the quantum (n,1)-matrix ball O_q(Mat_{n,1}). In order to prove the existence of an invariant integral, operator algebras are associated to O_q(Mat_{n,1}) which allow an interpretation as ``rapidly decreasing&#39;&#39; functions and as

Hjalmar Rosengren

Recently, Kajihara gave a Bailey-type transformation relating basic hypergeometric series on the root system An, with different dimensions n. We give, with a new, elementary, proof, an elliptic analogue of this transformation. We also obtain further Bailey-type transformations as consequences of our result, some of which are new also in the case of basic and

A. N. Panov

We study the irreducible representations of quantum solvable algebras at roots of 1 which lie over a point of the variety of center. We characterize the quiver of fiber algebra and present the formulas on the dimension and the number of these representations in terms of Poisson structure of the variety of center.

Sever Silvestru Dragomir

An Ostrowski type integral inequality for convex functions and applications for quadrature rules and integral means are given. A refinement and a counterpart result for Hermite-Hadamard inequalities are obtained and some inequalities for pdf&#39;s and (HH)-divergence measure are also mentioned.

Sever Silvestru Dragomir

A generalised trapezoid inequality for convex functions and applications for quadrature rules are given. A refinement and a counterpart result for the Hermite-Hadamard inequalities are obtained and some inequalities for pdf&#39;s and (HH)-divergence measure are also mentioned.

Sever Silvestru Dragomir

A new counterpart of Schwarz&#39;s inequality in inner product spaces and applications for isotonic functionals, integrals and sequences are provided.

Iain Raeburn, Aidan Sims

There has recently been much interest in the $C^*$-algebras of directed graphs. Here we consider product systems $E$ of directed graphs over semigroups and associated $C^*$-algebras $C^*(E)$ and $\mathcal{T}C^*(E)$ which generalise the higher-rank graph algebras of Kumjian-Pask and their Toeplitz analogues. We study these algebras by constructing from $E$ a

Iain Raeburn, Aidan Sims, Trent Yeend

We generalise the theory of Cuntz-Krieger families and graph algebras to the class of finitely aligned $k$-graphs. This class contains in particular all row-finite $k$-graphs. The Cuntz-Krieger relations for non-row-finite $k$-graphs look significantly different from the usual ones, and this substantially complicates the analysis of the graph algebra. We pro

Leopoldo Roman

Let $L$ be a complete orthomodular lattice. There is a one to one correspondence between complete boolean subalgebras of $L$ contained in the center of $L$ and endomorphisms $j$ of $L$ satisfying the Borceux-Van den Bossche conditions.

Wolfgang Bühring

An asymptotic expansion for a ratio of products of gamma functions is derived.

Theodora Ioannidou

The behavior of solitons in integrable theories is strongly constrained by the integrability of the theory, that is by the existence of an infinite number of conserved quantities that these theories are known to possess. As a result the soliton scattering of such theories are expected to be trivial (with no change of direction, velocity or shape). In this pa

Maja Buric, Voja Radovanovic

In this paper we calculate the divergent part of the one loop effective action for QED on noncommutative space using the background field method. The effective action is obtained up to the second order in the noncommutativity parameter $θ$ and in the classical fields.

Thorsten Leonhardt, Ruben Manvelyan, Werner Ruehl

We show that AdS two-point functions can be obtained by connecting two points in the interior of AdS space with one point on its boundary by a dual pair of Dobrev&#39;s boundary-to-bulk intertwiners and integrating over the boundary point.

Wang-Chang Su

Recently, Hirayama and Yamashita have presented an ansatz that allows us to construct a class of solutions for the SU(2) Skyrme model. Though these solutions are not solitonic, they provide us with an example on how the plane wave solutions arise in nonlinear field theories. In this paper, we investigate the applicability of the ansatz for the SU(3) Skyrme m

Mitsuo Hiragane, Yukinori Yasui, Hideki Ishihara

We investigate the Einstein equation with a positive cosmological constant for $4n+4$-dimensional metrics on bundles over Quaternionic Kähler base manifolds whose fibers are 4-dimensional Bianchi IX manifolds. The Einstein equations are reduced to a set of non-linear ordinary differential equations. We numerically find inhomogeneous compact Einstein spaces w

Nelia Mann, Joseph Polchinski

We study the holographic description of string theory in a plane wave spacetime by taking the Penrose limit of the usual AdS/CFT correspondence. We consider three-point functions with two BMN operators and one non-BMN operator; the latter should go over to a perturbation of the dual CFT. On the string side we take the Penrose limit of the metric perturbation

O-Kab Kwon, Piljin Yi

We study classical dynamics of an open string tachyon $T$ of unstable D$p$-brane coupled to the gauge field $A_μ$. In the vacuum with vanishing potential, V=0, two fluid-like degrees of freedom, string fluid and tachyon matter, survive the tachyon condensation. We offer general analysis of the associated Hamiltonian dynamics in arbitrary background. The cano

Jeffrey A. Bowers

We investigate color superconducting phases of cold quark matter at densities relevant for the interiors of compact stars. At these densities, electrically neutral and weak-equilibrated quark matter can have unequal numbers of up, down, and strange quarks. The QCD interaction favors Cooper pairs that are antisymmetric in color and in flavor, and a crystallin

F. Bezrukov, D. Levkov, C. Rebbi, V. Rubakov

We present a semiclassical study of the suppression of topology changing, baryon number violating transitions induced by particle collisions in the electroweak theory. We find that below the sphaleron energy the suppression exponent is remarkably close to the analytic estimates based on a low energy expansion about the instanton. Above the sphaleron energy,

Daniel Boer

A short review is given of QCD spin physics and its major aims: obtaining the polarized gluon density, the transversity distribution and understanding single spin asymmetries. The importance of the Drell-Yan process, the role of electron-positron colliders and the use of polarization to probe other, not spin specific physics are emphasized.

T. Teshima, I. Kitamura, N. Morisita

We analyze the mass spectroscopy of low and high mass scalar mesons and get the result that the coupling strengths of the mixing between low and high mass scalar mesons are very strong and the strengths of mixing for $I=1, 1/2$ scalar mesons and those of I=0 scalar mesons are almost same. Next, we analyze the decay widths and decay ratios of these mesons and

Osamu Yasuda

Degeneracies of the neutrino oscillation parameters are explained using the $\sin^22θ_{13}$--$s^2_{23}$ plane. Measurements of $\sin^22θ_{13}$ by reactor experiments are free from the parameter degeneracies which occur in accelerator appearance experiments, and reactor experiments play a role complementary to accelerator experiments. It is shown that the rea

Haiyan Gao, Bo-Qiang Ma

It is shown that the exotic non-qqq hadrons of pentaquark $qqqq\bar{q}$ states can be clearly distinguished from the conventional qqq-baryon resonances or their hybrids if the flavor of $\bar{q}$ is different from any of the other four quarks. We suggest the physical process $p(e,e&#39;K^-)Z(uuud\bar{s})$, which can be investigated at the Thomas Jefferson Na

Ying Li, Cai-Dian Lu

The rare decay B^+ \to D_s^+ \bar K^{*0} can occur only via annihilation diagrams in the Standard Model. We calculate the branching ratio in perturbative QCD approach based on k_T factorization theorem. We found that the branching ratio of this decay is about of order 10^{-8}, which may be sensitive to new physics.

F. L. Bezrukov, D. S. Gorbunov, Yu. G. Kudenko

We find that the normal muon polarization in the decay K->mu nu_mu gamma is very sensitive to the values of the kaon vector F_V and axial-vector F_A form factors. It is shown that the ongoing KEK-E246 experiment can definitely determine the signs of the sum of the form factors if their difference is fixed from other considerations. This method can also verif

V. Azcoiti, G. Di Carlo, A. Galante, V. Laliena

We apply to the $CP^9$ model two recently proposed numerical techniques for simulation of systems with a theta term. The algorithms, successfully tested in the strong coupling limit, are applied to the weak coupling region. The results agree and errors have been evaluated and are at % level. The results scale well with the renormalization group equation and

E. W. Vaandering

We describe a document database, developed for BTeV, which has now been adopted for use by other collaborations. A single web based database and archival system is used to maintain public and internal documents as well as documents for a related collaboration. The database performs archiving, versioning, access control, and easy remote access and submission.

R. Esposito, P. Mastroserio, G. Tortone, F. M. Taurino

Physics applications often involve large amounts of data and/or computing and often require secure resource sharing across organizational boundaries, and are thus not easily handled by today&#39;s Internet and Web infrastructures. Pamela (a Payload Antimatter Matter Exploration and Light-nuclei Astrophysics), is a permanent magnet core facility with a variet

G. Wagner

We present a measurement of the total width, Gamma_tot, and mass, M, of the eta_c meson with the BABAR detector at the PEP-II B-factory at SLAC. The results based on a data sample of 88 fb^-1 are Gamma_tot = (33.3 +- 2.5(stat.) +- 0.8(sys.))MeV and M = (2983.3 +- 1.2 +- 1.8) MeV. An enhancement observed around 3.63 GeV can be interpreted as an evidence for t

L3 Collaboration

Exclusive rho rho production in two-photon collisions involving a single highly virtual photon is studied with data collected at LEP at centre-of-mass energies 89GeV < \sqrt{s} < 209GeV with a total integrated luminosity of 854.7pb^-1 The cross section of the process gamma gamma^* -> rho rho is determined as a function of the photon virtuality, Q^2 and the t

T. Anticic, J. P. Baud, F. Carena, W. Carena

The ALICE experiment at CERN will propose unprecedented requirements for event building and data recording. New technologies will be adopted as well as ad-hoc frameworks, from the acquisition of experimental data up to the transfer onto permanent media and its later access. These issues justify a careful, in-depth planning and preparation. The ALICE Data Cha

Guillaume Faye, Gerhard Schaefer

The gravitational radiation-reaction force acting on perfect fluids at 3.5 post-Newtonian order is cast into a form which is directly applicable to numerical simulations. Extensive use is made of metric-coefficient changes induced by functional coordinate transformations, of the continuity equation, as well as of the equations of motion. We also present an e

Yury E. Pokrovsky

For slowly spinning matter the rate of energy loss via radiation of gravitational waves is estimated in General Relativity (GR) within a generally covariant superenergy approach. This estimation differs from Einstein&#39;s Quadrupole Formula (EQF) by a suppression factor ($Π\ll1$). For a symmetric two-body-like distribution of scalar matter $Π$ is estimated

Carl E. Dolby

The history of the particle concept is briefly reviewed, with particular emphasis on the `foliation dependence&#39; of many particle creation models, and the possible connection between our notion of particle and our notion of simultaneity. It is argued that the concept of `radar time&#39; (originally introduced by Sir Hermann Bondi in his work on k-calculus

Mauricio Osorio, Juan Antonio Navarro, Jose Arrazola

We present some applications of intermediate logics in the field of Answer Set Programming (ASP). A brief, but comprehensive introduction to the answer set semantics, intuitionistic and other intermediate logics is given. Some equivalence notions and their applications are discussed. Some results on intermediate logics are shown, and applied later to prove p

Hans C. Fogedby

We consider the combined influence of linear damping and noise on a dynamical finite-time-singularity model for a single degree of freedom. We find that the noise effectively resolves the finite-time-singularity and replaces it by a first-passage-time or absorbing state distribution with a peak at the singularity and a long time tail. The damping introduces

Grzegorz Szamel

A new theory for dynamics of concentrated colloidal suspensions and the colloidal glass transition is proposed. The starting point is the memory function representation of the density correlation function. The memory function can be expressed in terms of a time-dependent pair-density correlation function. An exact, formal equation of motion for this function

P. Pedri, D. Guéry-Odelin, S. Stringari

By means of a scaling ansatz, we investigate an approximated solution of the Boltzmann-Vlasov equation for a classical gas. Within this framework, we derive the frequencies and the damping of the collective oscillations of a harmonically trapped gas and we investigate its expansion after release of the trap. The method is well suited to studying the collisio

Boris Reusch, Hermann Grabert

We present detailed results of Unrestricted Hartree-Fock (UHF) calculations for up to eight electrons in a parabolic quantum dot. The UHF energies are shown to provide rather accurate estimates of the ground-state energy in the entire range of parameters from high densities with shell model characteristics to low densities with Wigner molecule features. To e

M. Cahay, S. Bandyopadhyay

A transfer matrix technique is used to model phase coherent spin transport in the weakly disordered quasi one-dimensional channel of a gate-controlled electron spin interferometer [Datta and Das, Appl. Phys. Lett., 56, 665 (1990)]. It includes the effects of an axial magnetic field in the channel of the interferometer (caused by the ferromagnetic contacts),

R. Mahendiran, P. Schiffer

We report studies of polycrystalline samples of the metallic ferromagnet Pr0.5Sr0.5CoO3 through measurements of the magnetization, a.c. magnetic susceptibility, resistivity, and specific heat. We find an unusual anomaly around TA = 120 K, much below the ferromagnetic transition (TC = 226 K). The anomaly is manifested in field cooled magnetization as a downwa

Houman Falakshahi, Zoltan Adam Nemeth, Jean-Louis Pichard

For an interacting system of N electrons, we study the conditions under which a lattice model of size L with nearest neighbor hopping t and U/r Coulomb repulsion has the same ground state as a continuum model. For a fixed value of N, one gets identical results when the inter-electron spacing to the Bohr radius ratio r_s < r_s^*. Above r_s^*, the persistent c

Cecile Monthus

We consider the dynamics of the disordered trap model, which is known to be completely out-of-equilibrium and to present strong localization effects in its aging phase. We are interested into the influence of an external force, when it is applied from the very beginning at $t=0$, or only after a waiting time $t_w$. We obtain a &#34;non-linear Fluctuation The

Sunil Nair, A. Banerjee

The second order para-ferromagnetic phase transition in a series of amorphous alloys (Fe{_5}Co{_{50}}Ni{_{17-x}}Cr{_x}B{_{16}}Si{_{12}}) is investigated using nonlinear susceptibility. A simple molecular field treatment for the critical region shows that the third order suceptibility (chi{_3}) diverges on both sides of the transition temperature, and changes

Zoltan Adam Nemeth, Jean-Louis Pichard

In this second paper, using N=3 polarized electrons (spinless fermions) interacting via a U/r Coulomb repulsion on a two dimensional L * L square lattice with periodic boundary conditions and nearest neighbor hopping, we show that a single unpaired fermion can co-exist with a correlated two particle Wigner molecule for intermediate values of the Coulomb ener

S. Sanvito

We present an extensive density functional theory study of the electronic, magnetic and transport properties of GaAs and AlAs digital ferromagnetic heterostructures. These can be obtained by $δ$-doping with Mn the GaAs layers of a GaAs/AlAs superlattice. Our analysis spans a range of Mn concentrations and considers the presence of compensating defects such a

Wellington da Cruz

We consider the fractal characteristic of the quantum mechanical paths and we obtain for any universal class of fractons labeled by the Hausdorff dimension defined within the interval 1$ $$ < $$ $$h$$ $$ <$$ $$ 2$, a fractal distribution function associated with a fractal von Neumann entropy. Fractons are charge-flux systems defined in two-dimensional multip

D. van der Marel

The f-sum rule is introduced and its applications to electronic and vibrational modes are discussed. A related integral over the intra-band part of sigma(omega) which is also valid for correlated electrons, becomes just the kinetic energy if the only hopping os between nearest-neighbor sites. A summary is given of additional sum-rule expressions for the opti

Stephane Courteau, David R. Andersen, Matthew A. Bershady, Lauren A. MacArthur

We present new data exploring the scaling relations, such as the Tully-Fisher relation (TFR), of bright barred and unbarred galaxies. A primary motivation for this study is to establish whether barredness correlates with, and is a consequence of, virial properties of galaxies. Various lines of evidence suggest that dark matter is dominant in disks of bright

M. L. Luhman, S. Satyapal, J. Fischer, M. G. Wolfire

We present a study of the [CII] 157.74 um fine-structure line in a sample of 15 ultraluminous infrared (IR) galaxies (L_IR>10^12 Lsun; ULIRGs) using the Long Wavelength Spectrometer (LWS) on the Infrared Space Observatory (ISO). We confirm the observed order of magnitude deficit (compared to normal and starburst galaxies) in the strength of the [CII] line re

T. Kiang

A more clear-cut answer to the title question is, ``Yes&#39;&#39; if the universal expansion started with a big bang; ``No&#39;&#39; if it started infinitely slowly.

Asantha Cooray

The measurement of angular diameter distance to galaxy clusters, through combined Sunyaev-Zel&#39;dovich (SZ) effect data with X-ray emission observations, is now a well-known probe of cosmology. Using a combination of SZ data and a map of the lensed CMB anisotropies by the galaxy cluster potential, we propose an alternative geometric technique to measure di

Masao Sako

Radiative transfer effects due to overlapping X-ray lines in a high-temperature, optically-thick, highly-ionized medium are investigated. One particular example, where the O VIII Ly-alpha doublet coincide in frequency with the N VII Ly-zeta lines is studied in detail to illustrate the effects on the properties of the emergent line spectrum. We solve the radi

R. B. C. Henry

Intermediate mass stars occupy the mass range between 0.8-8 solar masses. In this review, evolutionary models of these stars from numerous sources are compared in terms of their input physics and predicted yields. In particular, the results of Renzini & Voli, van den Hoek & Groenewegen, and Marigo are discussed. Generally speaking, it is shown that yields of

M. A. Stark, Richard A. Wade

Utilizing the Two Micron All Sky Survey (2MASS) Second Incremental Data Release Catalog, we have retrieved near-IR magnitudes for several hundred hot subdwarfs (sdO and sdB stars) drawn from the &#34;Catalogue of Spectroscopically Identified Hot Subdwarfs&#34; (Kilkenny, Heber, & Drilling 1988, 1992). This sample size greatly exceeds that of previous studies

G. G. Pavlov, M. A. Teter, O. Kargaltsev, D. Sanwal

Observations of the Vela pulsar-wind nebula (PWN) with the Chandra X-ray Observatory have revealed a complex, variable PWN structure, including inner and outer arcs, a jet in the direction of the pulsar&#39;s proper motion, and a counter-jet in the opposite direction, embedded in diffuse nebular emission. From the analysis of thirteen Chandra observations sp

Kazutaka Motoyama, Tatsuo Yoshida

Recent observations indicate that some class 0 sources have orders of magnitude higher accretion rates than those of class I. We investigated the conditions for the high accretion rates of some class 0 sources by numerical calculations, modelling an external trigger. For no external trigger, we find that the maximum value of the accretion rate is determined

T. Boeker, U. Lisenfeld, E. Schinnerer

Using the IRAM 30m telescope, we have surveyed an unbiased sample of 47 nearby spiral galaxies of very late (Scd-Sm) Hubble-type for emission in the CO(1-0) and CO(2-1) lines. The sensitivity of our data (a few mK) allows detection of about 60% of our sample in at least one of the CO lines. The median detected H2 mass is $1.4\times 10^7 \msun$ within the cen

J. -J. Tseng, T. -W. Yeh, H. Athar, M. A. Huang

We present a semi-analytic calculation of the tau-lepton flux emerging from the Earth, induced by the incident high energy neutrinos interacting inside the Earth for $10^{5} \leq E_ν/{\rm GeV} \leq 10^{10}$. We obtain results for the energy dependence of the tau-lepton flux coming from the Earth-skimming neutrinos, because of the neutrino-nucleon charged-cur

L. Baldacci, F. Matonti, L. Rizzi, G. Clementini

Results are presented of a study of the variable star populations in the dwarf spheroidal galaxy Leo I and in the dwarf irregular galaxy NGC 6822, based on time series photometry obtained with the Wide Field Imager of the 2.2 m ESO/MPI telescope (Leo I) and the Very Large Telescope (NGC 6822). We found about 250 (lower limit) variables in Leo I most of which

R. Della Ceca, V. Braito, V. Beckmann, A. Caccianiga

We discuss the X-ray, optical and radio properties of AX J0843+2942, a high luminosity Type 2 AGN found in the ASCA Hard Serendipitous Survey. The X-ray spectrum is best described by an absorbed power-law model with photon index of Gamma = 1.72 (+0.3 -0.6) and intrinsic absorbing column density of NH = 1.44 (+0.33 -0.52) x 10E23 cm-2. The intrinsic luminosit

Ya. Tikhomirova, B. E. Stern

Before the BATSE/GRO launch GRBs seem to be a uniform phenomenon with duration up to about 100 seconds. The BATSE has detected many events longer than 100 s and a few longer than 500s. We performed the off-line scan of the 1024 ms continuous BATSE records and revealed several non-triggered episodes of the BATSE GRB triggers which confidently belong to the sa

Jacco Th. van Loon, Joana M. Oliveira

We report on the discovery of a mid-infrared source at a projected distance of only 1200 AU from the O9.5 V star sigma Orionis. The spatially resolved, fan-shaped morphology and the presence of an ionization front, as well as evidence in the spectrum for processed dust grains, all suggest that it is a proto-planetary disk being dispersed by the intense ultra

J. M. Oliveira, R. D. Jeffries, J. Th. van Loon, M. J. Kenyon

The sigma Orionis cluster is a young association evolving under the disruptive influence of its massive O-star namesake. We are analysing this cluster as part of a program to characterise the influence of O-stars on the early stages of stellar evolution. At an age of approximately 4 Myr, this cluster is at a crucial stage in terms of disk evolution and there

Barrie W Jones, David R Underwood, P Nick Sleep

We have shown that Earth-mass planets could survive in variously restricted regions of the habitable zones (HZs) of most of a sample of nine of the 93 main-sequence exoplanetary systems confirmed by May 2003. In a preliminary extrapolation of our results to the other systems, we estimate that roughly a third of the 93 systems might be able to have Earth-mass

K. Heike, H. Awaki, Y. Misao, K. Hayashida

From the analysis of a ~100 ks Chandra observation of the dwarf starburst galaxy NGC 1569, we have found that the X-ray point sources, CXOU 043048.1+645050 and CXOU 043048.6+645058, showed significant time variability. During this observation, the X-ray flux of CXOU 043048.1+645050 increased by 10 times in only 2 x 10^4 s. Since the spectrum in its bright ph