August 2002 arXiv papers — page 16

Giorgio Fontana

It is well known that excited quantum systems can emit gravitons as well as photons. Differently from photon emission, spontaneous graviton emission is characterized by such a low probability that stimulated emission appears the only possible mechanism for producing gravitational radiation with quantum systems. The principles of the gravitational counterpart

Annamaria Borriello, Paolo Salucci, Luigi Danese

We show that the small scatter around the Fundamental Plane (FP) of massive elliptical galaxies can be used to derive important properties of their dark and luminous matter. The central velocity dispersion sigma_0, appearing in (e.g.) the Fundamental Plane, is linked to photometric, dynamical and geometrical properties of (luminous and dark) matter. We find

Debashis Gangopadhyay, Rajsekhar Bhattacharyya, L. P. Singh

This paper has been withdrawn by the authors in order to replace it with a more correct treatment. The basic results remain the same but the treatment is more rigorously correct.

A. Kogan, G. Granger, M. A. Kastner, D. Goldhaber-Gordon

We report sharp peaks in the differential conductance of a single-electron transistor (SET) at low temperature, for gate voltages at which charge fluctuations are suppressed. For odd numbers of electrons we observe the expected Kondo peak at zero bias. For even numbers of electrons we generally observe Kondo-like features corresponding to excited states. For

L. Arevalo Aguilar, H. Moya-Cessa

We study the effects of counter rotating terms in the interaction of quantized light with a two-level atom, by using the method of small rotations. We give an expression for the wave function of the composed system atom plus field and point out one initial wave function that generates a quantum bit of the electromagnetic field with arbitrary amplitudes.

H. Moya-Cessa, R. Juarez-Amaro, I. Ricardez-Vargas

We show that the Q-function corresponding to an electromagnetic field in a lossy cavity can be directly measured by means of a simple scheme, therefore allowing the knowledge of the state of the field despite dissipation.

Hector Moya-Cessa

One of the most prominent quasiprobability functions in quantum mechanics is the Wigner function that gives the right marginal probability functions if integrated over position or momentum. Here we depart from the definition of the position-momentum Wigner function to, in analogy, construct a number-phase Wigner function that, if summed over photon numbers g

Alfredo M. Ozorio de Almeida

The Lindblad equation governs general markovian evolution of the density operator in an open quantum system. An expression for the rate of change of the Wigner function as a sum of integrals is one of the forms of the Weyl representation for this equation. The semiclassical description of the Wigner function in terms of chords, each with its classically defi

N. Linden, W. K. Wootters

We show that almost every pure state of multi-party quantum systems (each of whose local Hilbert space has the same dimension) is completely determined by the state's reduced density matrices of a fraction of the parties; this fraction is less than about two-thirds of the parties for states of large numbers of parties. In other words once the reduced sta

H. K. Cummins, G. Llewellyn, J. A. Jones

We describe the use of composite rotations to combat systematic errors in single qubit quantum logic gates and discuss three families of composite rotations which can be used to correct off-resonance and pulse length errors. Although developed and described within the context of NMR quantum computing these sequences should be applicable to any implementation

Martin Hendrych, Miloslav Dusek, Radim Filip, Jaromir Fiurasek

We present the experimental results of measurements of the overlap of both pure and mixed polarization states of photons. The fidelity and purity of mixed states were also measured. The experimental apparatus exploits the fact that a beam splitter can distinguish the singlet Bell state from the other Bell states, i.e., it realizes projections into the symmet

Shao-Ming Fei, Xiu-Hong Gao, Xiao-Hong Wang, Zhi-Xi Wang

Explicit sufficient and necessary conditions for separability of $N$-dimensional rank two multiparty quantum mixed states are presented. A nonseparability inequality is also given, for the case where one of the eigenvectors corresponding to nonzero eigenvalues of the density matrix is maximally entangled.

Tomohiro Ogawa, Masahito Hayashi

In the simple quantum hypothesis testing problem, upper bounds on the error probabilities are shown based on a key operator inequality between a density operator and its pinching. Concerning the error exponents, the upper bounds lead to a noncommutative analogue of the Hoeffding bound, which is identical with the classical counter part if the hypotheses, com

Jean M. Deken

As part of their efforts to consistently and reliably identify and preserve the archival records of their organizations, archivists are trying to address the issue of appraising and collecting World Wide Web documents. This paper discusses the approach taken at the Stanford Linear Accelerator Center to collect and preserve documentation of the first World Wi

Tatyana Sharpee, Nicole C. Rust, William Bialek

We propose a method that would allow for a rigorous statistical analysis of neural responses to natural stimuli, which are non-Gaussian and exhibit strong correlations. We have in mind a model in which neurons are selective for a small number of stimulus dimensions out of the high dimensional stimulus space, but within this subspace the responses can be arbi

Frank X. Lee

N* masses in the spin-1/2 and spin-3/2 sectors are computed using two non-perturbative methods: lattice QCD and QCD sum rules. States with both positive and negative parity are isolated via parity projection methods. The basic pattern of the mass splittings is consistent with experiments. The mass splitting within the same parity pair is directly linked to t

Calvin W. Johnson, Ionel Stetcu

We calculate the ground-state expectation value of scalar observables in the matrix formulation of the random phase approximation (RPA). Our expression, derived using the quasiboson approximation, is a straightforward generalization of the RPA correlation energy. We test the reliability of our expression by comparing against full diagonalization in 0 h-bar o

Ingo Sick

The charge and magnetic form factors of light nuclei, mainly for mass numbers A<=4, provide a sensitive test of our understanding of nuclei. A number of &#34;exact&#34; calculations of the wave functions starting from the nucleon-nucleon interaction are available. The treatment of two-body effects needed in the calculation of the electromagnetic form factors

Fritz Gesztesy, Helge Holden

We provide a treatment of real-valued, smooth, and bounded algebro-geometric solutions of the Camassa--Holm (CH) hierarchy and describe the associated isospectral torus. We also discuss real-valued algebro-geometric solutions with a cusp behavior.

M. Abel

In this article, it is described how to use statistical data analysis to obtain models directly from data. The focus is put on finding nonlinearities within a generalized additive model. These models are found by the means of backfitting algorithms or more general versions, like the alternating conditional expectation value method. The method is illustrated

Markus J. Pflaum

In the first part of this article we provide a geometrically oriented approach to the theory of orbispaces which originally had been introduced by Chen. We explain the notion of a vector orbibundle and characterize the good sections of a reduced vector orbibundle as the smooth stratified sections. In the second part of the article we elaborate on the quantiz

Tom Weston

Let A be an abelian variety over a number field F with End(A/F) commutative. Let S be a subgroup of A(F) and let x be a point of A(F). Suppose that for almost all places v of F the reduction of x modulo v lies in the reduction of S modulo v. In this paper we prove that x must then lie in S + A(F)_tors. This provides a partial answer to a generalization (due

Sean Cleary, Jennifer Taback

We study some combinatorial properties of the word metric of Thompson&#39;s group F in the standard two generator finite presentation. We explore connections between the tree pair diagram representing an element w of F, its normal form in the infinite presentation, its word length, and minimal length representatives of it. We estimate word length in terms of

Rafe Mazzeo, Andras Vasy

In this paper we continue our program of extending the methods of geometric scattering theory to encompass the analysis of the Laplacian on symmetric spaces of rank greater than one and their geometric perturbations. In our previous work we described the resolvent, and specifically the asymptotic behavior of the Green&#39;s function, on SL(3)/SO(3) using met

Henk Bruin, Stefano Luzzatto, Sebastian van Strien

We consider multimodal C^3 interval maps f satisfying a summability condition on the derivatives D_n along the critical orbits which implies the existence of an absolutely continuous f -invariant probability measure mu. If f is non-renormalizable, mu is mixing and we show that the speed of mixing (decay of correlations) is strongly related to the rate of gro

David Garber, Mina Teicher

In this paper, we give a fully detailed exposition of computing fundamental groups of complements of line arrangements using the Moishezon-Teicher technique for computing the braid monodromy of a curve and the Van-Kampen theorem which induces a presentation of the fundamental group of the complement from the braid monodromy of the curve. For example, we trea

Alexander Polishchuk

This paper is a sequel to math.AG/0011032. Its goal is to show that Witten&#39;s &#34;top Chern class&#34; constructed in loc.cit. satisfies all the axioms of math.AG/9905034.

Grzegorz Karch, Maria E. Schonbek

In the paper, we consider the large time behavior of solutions to the convection-diffusion equation u_t - Delta u + nabla cdot f(u) = 0 in R^n times [0,infinity), where f(u) ~ u^q as u --> 0. Under the assumption that q >= 1+1/(n+beta) and the initial condition u_0 satisfies: u_0 in L^1(R^n), integral_{R^n} u_0(x) dx = 0, and |e^{t Delta}u_0|_{L^1(R^n)} <= C

Saul Schleimer

A surface automorphism is strongly irreducible if every essential simple closed curve in the surface has nontrivial geometric intersection with its image. We show that a three-manifold admits only finitely many inequivalent surface bundle structures with strongly irreducible monodromy.

Tobias H. Colding, Camillo De Lellis

For any 3-manifold M and any nonnegative integer g, we give here examples of metrics on M each of which has a sequence of embedded minimal surfaces of genus g and without Morse index bounds. On any spherical space form S^3/Gamma we construct such a metric with positive scalar curvature. More generally we construct such a metric with Scal>0 (and such surfaces

Shrawan Kumar, Jesper Funch Thomsen

We relate the n! conjecture (by Garsia and Haiman) to the geometry of principal nilpotent pairs, and state a conjecture generalizing the n! conjecture to arbitrary semisimple algebraic groups. We also show, using Borel&#39;s fixed point theorem, how to reduce the n! conjecture to staircase partitions. Finally we study the interplay between characteristic p a

Volker Kaibel, Alexander Schwartz

We show that the problem to decide whether two (convex) polytopes, given by their vertex-facet incidences, are combinatorially isomorphic is graph isomorphism complete, even for simple or simplicial polytopes. On the other hand, we give a polynomial time algorithm for the combinatorial polytope isomorphism problem in bounded dimensions. Furthermore, we deriv

Volker Kaibel, Marc E. Pfetsch

We give an algorithm that constructs the Hasse diagram of the face lattice of a convex polytope P from its vertex-facet incidences in time O(min{n,m}*a*f), where n is the number of vertices, m is the number of facets, a is the number of vertex-facet incidences, and f is the total number of faces of P. This improves results of Fukuda and Rosta (1994), who des

G. Rodrigues

We define Homotopy quantum field theories (HQFT) as Topological quantum field theories (TQFT) for manifolds endowed with extra structure in the form of a map into some background space X. We also build the category of homotopy cobordisms HCobord(n,X) such that an HQFT is a functor from this category into a category of linear spaces. We then derive some very

S. James Gates,, Lubna Rana

We investigate a minimal superspace description for 5D superconformal Killing vectors. The vielbein appropriate for AdS symmetry is discussed within the confines of this minimal supergeometry.

D. Bailin, G. V. Kraniotis, A. Love

We construct a new set of intersecting D4-brane models that yield the (non-supersymmetric) standard model up to vector-like matter and, in some cases, extra U(1) factors in the gauge group. The models are constrained by the requirement that twisted tadpoles cancel, and that the gauge boson coupled to the weak hypercharge U(1)_Y does not get a string-scale ma

Valeri Frolov, Dejan Stojkovic

A small black hole attached to a brane in a higher dimensional space emitting quanta into the bulk may leave the brane as a result of a recoil. We construct a field theory model in which such a black hole is described as a massive scalar particle with internal degrees of freedom. In this model, the probability of transition between the different internal lev

Ruth Gregory

We consider classical solutions for strings ending on magnetically charged black holes in four-dimensional Kaluza-Klein theory. We examine the classical superstring and the global vortex, which can be viewed as a nonsingular model for the superstring. We show how both of these can end on a Kaluza-Klein monopole in the absence of self-gravity. Including gravi

S. A. Alavi

We introduce the perturbative aspects of noncommutative quantum mechanics. Then we study the Berry&#39;s phase in the framework of noncommutative quantum mechanics. The results show deviations from the usual quantum mechanics which depend on the parameter of space/space noncommtativity.

Gia Dvali, Gregory Gabadadze, M. Shifman

We review a solution of the cosmological constant problem in a brane-world model with infinite-volume extra dimensions. The solution is based on a nonlinear generally covariant theory of a metastable graviton that leads to a large-distance modification of gravity. From the extra-dimensional standpoint the problem is solved due to the fact that the four-dimen

Csaba Csaki, Joshua Erlich, John Terning

It has recently been suggested that, in a large N limit, a particular four dimensional gauge theory is indistinguishable from the six dimensional CFT with (0,2) supersymmetry compactified on a torus. We give further evidence for this correspondence by studying the Seiberg-Witten curve for the &#34;deconstructed&#34; theory and demonstrating that along the re

Alakabha Datta, David London

The decays B_{d,s}^0 --> K^{(*)} K-bar^{(*)} can be used to measure the angle alpha of the CKM unitarity triangle. The theoretical error from SU(3) breaking is expected to be small, so that the determination of alpha is clean. Moreover, since B_{d,s}^0 --> K^{(*)} K-bar^{(*)} are pure penguin decays, they are particularly sensitive to the presence of new phy

William B. Kilgore

I report on a calculation of the inclusive Higgs boson production cross section at hadron colliders at next-to-next-to-leading order in QCD. The result is computed as an expansion about the threshold region. By continuing the expansion to very high order, we map the result onto basis functions and obtain the result in closed analytic form.

F. Gelis, Jamal Jalilian-Marian

We consider dilepton production in high energy proton-nucleus (and very forward nucleus-nucleus) collisions. Treating the target nucleus as a Color Glass Condensate and describing the projectile proton (nucleus) as a collection of quarks and gluons as in the parton model, we calculate the differential cross section for dilepton production in quark-nucleus sc

Anne M. Green

Weakly Interacting Massive Particle (WIMP) direct detection experiments are closing in on the region of parameter space where relic neutralinos may constitute the galactic halo dark matter. We discuss two issues in the interpretation of data, in particular the calculation of exclusion limits, from these experiments. Firstly we show that the technique that ha

Wieslaw Placzek

Theoretical calculations for the W-pair production process at LEP2 in terms of Monte Carlo event generators RacoonWW and KorlaW&YFSWW3 are reviewed. The discussion concentrates on precision predictions for the main LEP2 WW observables. The theoretical precision of the above programs is estimated to be ~0.5% for the total WW cross section sigma_{WW}, ~5MeV fo

Johan Hansson

We show that the non-appearance of gluons and quarks as physical particles is a rigorous and automatic result of the full, i.e. nonperturbative, nonabelian nature of the color interaction in quantum chromodynamics. This makes it in general impossible to describe the color field as a collection of elementary quanta (gluons). Neither can a quark be an elementa

Jean-Jacques Dugne, Sverker Fredriksson, Johan Hansson

Quarks, leptons and heavy vector bosons are suggested to be composed of stable spin-1/2 preons, existing in three flavours, combined according to simple rules. Straightforward consequences of an SU(3) preon-flavour symmetry are the conservation of three lepton numbers, oscillations and decays between some neutrinos, and the mixing of the d and s quarks, as w

Harleen Dahiya, Manmohan Gupta

Baryon octet magnetic moments when calculated within the chiral quark model, incorporating the orbital angular momentum as well as the quark sea contribution through the Cheng-Li mechanism, not only show improvement over the non relativistic quark model results but also gives a non zero value for the right hand side of Coleman-Glashow sum rule. When effects

J. Kiskis, R. Narayanan. H. Neuberger

Some results in QCD_2 at large N are presented using the reduced model on the lattice. Overlap fermions are used to compute meson propagators.

Roberto Fiore, Alessandro Papa, Paolo Provero

We study the spectrum of screening masses in the deconfined phase of (3+1)D SU(2) pure gauge theory near criticality and compare it with the spectrum of bound states in the broken symmetry phase of the 3D Ising model, which is related to the gauge theory by universality.

Rajiv V. Gavai, Sourendu Gupta

We report the first investigation of the QCD transition temperature, T_c, for two flavours of staggered quarks with unequal masses at lattice spacings of 1/4T. On changing the u/d quark mass ratio in such a way that m(pi_0)^2/m(pi_+)^2 changes from 1 to 0.78, thus bracketing the physical value of this ratio, we find that T_c remains unchanged in units of bot

Margarita Safonova, Diego F. Torres

We present three different theoretically foreseen, but unusual, astrophysical situations where the gravitational lens equation ends up being the same, thus producing a degeneracy problem. These situations are (a) the case of gravitational lensing by exotic stresses (matter violating the weak energy condition and thus having a negative mass, particular cases

J. G. Pereira, T. Vargas

In the context of the teleparallel equivalent of general relativity, the Weitzenbock manifold is considered as the limit of a suitable sequence of discrete lattices composed of an increasing number of smaller an smaller simplices, where the interior of each simplex (Delaunay lattice) is assumed to be flat. The link lengths between any pair of vertices serve

G. A. Kohring

A novel algorithm for performing parallel, distributed computer simulations on the Internet using IP control messages is introduced. The algorithm employs carefully constructed ICMP packets which enable the required computations to be completed as part of the standard IP communication protocol. After providing a detailed description of the algorithm, experim

A. Serquis, L. Civale, D. L. Hammon, J. Y. Coulter

We report dc transport and magnetization measurements of Jc in MgB2 wires fabricated by the powder-in-tube method, using commercial MgB2 powder with 5 %at Mg powder added as an additional source of magnesium, and stainless steel as sheath material. By appropriate heat treatments, we have been able to increase Jc by more than one order of magnitude from that

Yaroslav Tserkovnyak, David Linton Johnson

We extend earlier work on nonlinear tube wave propagation in permeable formations to study, analytically and numerically, the generation and propagation of a difference frequency, Delta omega = omega_1 - omega_2, due to an initial pulse consisting of carrier frequencies omega_1 and omega_2. Tube waves in permeable formations have very significant linear disp

Todd L. Duncan

Claims of exceptions to the second law of thermodynamics are generally met with extreme skepticism that is quite reasonable given the great confidence placed in the second law. But what specifically is the basis for that confidence? The perspective from which we approach experimental or theoretical results that call into question the absolute status of the s

Yaroslav Tserkovnyak, David Linton Johnson

The theory of the acoustics of patchy-saturation in porous media is used to analyze experimental data on wave velocity and attenuation in partially water saturated limestones. It is demonstrated that the theory can be used to deduce the value of V/A, the ratio of the volume to area of the water patch, and l_f, the Poisson size of the water patch. One can ``h

P. Abbamonte, L. Venema, A. Rusydi, G. A. Sawatzky

An unresolved issue concerning cuprate superconductors is whether the distribution of carriers in the CuO(2) plane is uniform or inhomogeneous. Because the carriers comprise a small fraction of the total charge density and may be rapidly fluctuating, modulations are difficult to detect directly. Here we demonstrate that in anomalous x-ray scattering at the o

T. Scheffler, D. E. Wolf

The dissipation rate due to inelastic collisions between equally charged, insulating particles in a granular gas is calculated. It is equal to the known dissipation rate for uncharged granular media multiplied by a Boltzmann-like factor, that originates from Coulomb repulsion. Particle correlations lead to an effective potential that replaces the bare Coulom

Germano S. Iannacchione, Sungil Park, Carl W. Garland, Robert J. Birgeneau

Liquid crystals offer many unique opportunities to study various phase transitions with continuous symmetry in the presence of quenched random disorder (QRD). The QRD arises from the presence of porous solids in the form of a random gel network. Experimental and theoretical work support the view that for fixed (static) inclusions, quasi-long-range smectic or

M. A. Hein, R. G. Humphreys, P. J. Hirst, S. H. Park

We have investigated the nonlinear microwave properties of electron-beam coevaporated YBaCuO films on MgO, using stripline resonators at 2.3 GHz and temperatures 1.7-80 K. The oxygen content of the films ranged from strongly underdoped to overdoped. Above 20 K, the nonlinear response of the resonators was dominated by the superconductor. We could establish c

R. L. Leheny, S. Park, R. J. Birgeneau, J. -L. Gallani

Comprehensive x-ray scattering studies have characterized the smectic ordering of octylcyanobiphenyl (8CB) confined in the hydrogen-bonded silica gels formed by aerosil dispersions. For all densities of aerosil and all measurement temperatures, the correlations remain short range, demonstrating that the disorder imposed by the gels destroys the nematic (N) t

D. Bolle&#39;, D. R. C. Dominguez, R. Erichsen, E. Korutcheva

The time evolution of the extremely diluted Blume-Emery-Griffiths neural network model is studied, and a detailed equilibrium phase diagram is obtained exhibiting pattern retrieval, fluctuation retrieval and self-sustained activity phases. It is shown that saddle-point solutions associated with fluctuation overlaps slow down considerably the flow of the netw

Silvio Franz, Michele Leone

In this paper we generalize to the case of diluted spin models and random combinatorial optimization problems a technique recently introduced by Guerra (cond-mat/0205123) to prove that the replica method generates variational bounds for disordered systems. We analyze a family of models that includes the Viana-Bray model, the diluted p-spin model or random XO

N. Deo

The Chiral Random Matrix Model or the Gaussian Penner Model (generalized Laguerre ensemble) is re-examined in the light of the results which have been found in double well matrix models [D97,BD99] and subtleties discovered in the single well matrix models [BH99]. The orthogonal polynomial method is used to extend the universality to include non-polynomial po

Matthew T. Glossop, David E. Logan

A non-perturbative local moment approach to single-particle dynamics of the general asymmetric Anderson impurity model is developed. The approach encompasses all energy scales and interaction strengths. It captures thereby strong coupling Kondo behaviour, including the resultant universal scaling behaviour of the single-particle spectrum; as well as the mixe

Holger Ebel, Stefan Bornholdt

We study agents on a network playing an iterated Prisoner&#39;s dilemma against their neighbors. The resulting spatially extended co-evolutionary game exhibits stationary states which are Nash equilibria. After perturbation of these equilibria, avalanches of mutations reestablish a stationary state. Scale-free avalanche distributions are observed that are in

Yevgeni Preezant, Nir Tessler

Self-consistent solution of charge injection and transport in low mobility LEDs is reported . We show that explicit description of the contact region under the same premise as transport equation is needed to accurately evaluate the current-voltage characteristics of polymer or small-molecule based LEDs . The result is compared to widely used models, which tr

M. Molotskii, V. Fleurov

We propose an explanation of the anomalous growth of plasticity in ferromagnets near the Curie point. We demonstrate that this effect is caused by spin-dependent detachment of dislocations from obstacles under an influence of the internal magnetic field. Magnetization fluctuations grow in the vicinity of the Curie point, yield an increase of the detachment p

Sundaram Balasubramanian, Subrata Pal, Biman Bagchi

The dynamics of hydrogen bonds among water molecules themselves and with the polar head groups (PHG) at a micellar surface have been investigated by long molecular dynamics simulations. The lifetime of the hydrogen bond between a PHG and a water molecule is found to be much longer than that between any two water molecules, and is likely to be a general featu

Ligang Chen, Michael W. Deem

How best to design and redesign high-throughput experiments for zeolite synthesis is addressed. A model that relates materials function to chemical composition of the zeolite and the structure directing agent is introduced. Using this model, several Monte Carlo-like design protocols are evaluated. Multi-round protocols are found to be effective, and strategi

C. C. Popescu, R. J. Tuffs

We show that the mean percentage of stellar light re-radiated by dust is ~30 percent for the Virgo Cluster late-spirals measured with ISOPHOT by Tuffs et al. (2002). A strong dependence of this ratio with morphological type was found, ranging from typical values of ~15 percent for early spirals to up to ~50 percent for some late spirals. The extreme BCDs can

C. Palma, S. Zonak, S. Hunsberger, J. Charlton

Hubble Space Telescope Wide Field Planetary Camera 2 images of Hickson Compact Group 79, Seyfert&#39;s Sextet, are presented. Both point sources and extended sources detected on the three WF chips were photometered in four filters: F336W, F439W, F555W, and F814W. Unlike other HCGs that have been imaged with HST, there do not appear to be any candidate young

Anil Seth, Lincoln Greenhill, Benjamin Holder

We have mapped the water maser emission associated with the infrared centers IRS1 and IRS3 of the NGC 2071IR star forming region at four epochs over ~4 months with the Very Long Baseline Array (VLBA). We detected 269 maser features with ~1 km/sec linewidths and measured 30 proper motions. In each infrared center, the water maser emission appears to trace par

Eric M. Splaver, David J. Nice, Zaven Arzoumanian, Fernando Camilo

Orbital, spin and astrometric parameters of the millisecond pulsar PSR J0621+1002 have been determined through six years of timing observations at three radio telescopes. The chief result is a measurement of the rate of periastron advance, omega_dot = 0.0116 +/- 0.0008 deg/yr. Interpreted as a general relativistic effect, this implies the sum of the pulsar m

J. E. Grindlay, F. Camilo, C. O. Heinke, P. D. Edmonds

We report Chandra observations of the complete sample of millisecond pulsars (MSPs) with precise radio positions in the globular clusters 47Tuc (NGC104) and NGC6397. The 47Tuc MSPs are predominantly soft sources suggestive of thermal emission from small (r_x < 0.6km) polar caps on the neutron star rather than magnetospheric emission and are a relatively homo

E. Masciadri, E. M. de Gouveia Dal Pino, A. C. Raga, A. Noriega-Crespo

The giant jets represent a fundamental trace of the historical evolution of the outflow activity over timescales which are comparable to the accretion time of the outflow sources in their main protostellar phase. The study of such huge jets provides the possibility of retrieving important elements related to the life of the outflow sources. In this paper, we

A. Kundu, S. R. Majewski, J. Rhee, H. J. Rocha-Pinto

We describe first results of a spectroscopic probe of selected fields from the Grid Giant Star Survey. Multifiber spectroscopy of several hundred stars in a strip of eleven fields along delta approximately -17^{circ}, in the range 12 <~ alpha <~ 17 hours, reveals a group of 8 giants that have kinematical characteristics differing from the main field populati

T. T. Barnaveli, T. T. Barnaveli, A. P. Chubenko, N. A. Eristavi

The dependence E_h (N_e) of Extensive Air Shower (EAS) hadronic component energy flux on the number N_e of particles in EAS is investigated in the primary energy range of the order of 10^{15} - 10^{17} eV. The work was aimed at checking the existence of irregularities of E_h (N_e)/N_e behavior at these energies in several independent experiments. The investi

O. Vilhu, D. Hannikainen

We propose a scenario for a periodic filling and emptying of the accretion disc of GRS 1915+105, by computing the mass transfer rate from the donor and comparing it with the observed accretion rate. The binary parameters found by Greiner et al. (2001) predict evolutionary expansion of the donor along the giant branch with a conservative mass transfer rate (1

J. Kijak, J. Gil

Structure of mean pulsar radiation patterns is discussed within the nested-cones and patchy beam models. Observational predictions of both these models are analyzed and compared with available data on pulsar waveforms. It is argued that observational properties of pulsar waveforms are highly consistent with the nested-cone model and, in general, inconsistent

Vincent M. Woolf, C. Simon Jeffery

We report the analysis of optical spectra of the extreme helium star LSS 3184 (BX Cir) to determine its effective temperature and gravity throughout its pulsation cycle. The spectra were also used to measure its chemical abundances. We report rest gravity, log g = 3.38 +/- 0.02, and a chemical abundance mixture consistent with those reported earlier in a stu

Marcus Ansorg, Andreas Kleinwächter, Reinhard Meinel

We give a thorough investigation of sequences of uniformly rotating, homogeneous axisymmetric Newtonian equilibrium configurations that bifurcate from highly flattened Maclaurin spheroids. Each one of these sequences possesses a mass-shedding limit. Starting at this point, the sequences proceed towards the Maclaurin sequence and beyond. The first sequence le

J. P. Dietrich, D. I. Clowe, G. Soucail

We present a spectroscopic catalog of the neighboring massive clusters Abell 222 and Abell 223. The catalog contains the positions, redshifts, R magnitudes, V-R color, as well as the equivalent widths for a number of lines for 183 galaxies, 153 of them belonging to the A 222 and A 223 system. We determine the heliocentric redshifts to be z=0.2126+/-0.0008 fo

Mofazzal Azam

The ultra-low density limit of Saha ionization formula suggests that, in this limit, matter would prefer to remain ionized.This has a very important implication for cosmic structures known as Voids.These are ultra-low density (much less than average density of matter in the Universe) regions in the galactic clusters and superclusters.The ionization formula i

Bruce Wilking, Ayman Mikhail, Glenn Carlson, Michael Meyer

We present an analysis of low-resolution infrared spectra for 25 brown dwarf candidates in the NGC 1333 molecular cloud. Candidates were chosen on the basis of their association with the high column density cloud core, and near-infrared fluxes and colors. We compare the depths of water vapor absorption bands in our candidate objects with a grid of dwarf, sub

J. J. Fortney, D. Sudarsky, I. Hubeny, C. S. Cooper

Using a self-consistent atmosphere code, we construct a new model of the atmosphere of the transiting extrasolar giant planet HD 209458b to investigate the disparity between the observed strength of the sodium absorption feature at 589 nm and the predictions of previous models. For the atmospheric temperature-pressure profile we derive, silicate and iron clo

E. Altshuler, T. H. Johansen, Y. Paltiel, Peng Jin

In 1993 Tang proposed [1] that vortex avalanches should produce a self organized critical state in superconductors, but conclusive evidence for this has heretofore been lacking. In the present paper, we report extensive micro-Hall probe data from the vortex dynamics in superconducting niobium, where a broad distribution of avalanche sizes scaling as a power-

N. V. Ustinov

The sets of the integrable lattice equations, which generalize the Toda lattice, are considered. The hierarchies of the first integrals and infinitesimal symmetries are found. The properties of the multi-soliton solutions are discussed.

V. Braguta, A. Chalov, A. Likhoded, R. Rosenfeld

We perform a complete simulation of the process e^+ e^- --> b b-bar nu nu-bar, where nu can be an electron, muon or tau neutrino, in the context of a general Higgs coupling to b quarks. We parametrize the H b b-bar coupling as m_b/v (a + i gamma_5 b). Taking into account interference effects between pure Higgs and Standard Model contributions, we find that s

Rodrigo Aros

In this work the algebra of charges of diffeomorphisms at the horizon of generic black holes is analyzed within first order gravity. This algebra reproduces the algebra of diffeomorphisms at the horizon, (Diff(S^1)), without central extension.

Shinji Mukohyama

We investigate light-cone structure on the world-volume of an unstable D-brane with a tachyon decaying inhomogeneously by using a field theoretical description. It is shown that (i) light-cones governing open strings are narrower than those governing closed strings and will eventually collapse inward in all directions except at kinks, where the tachyon remai

W. Grimus, M. Maltoni, T. Schwetz, M. A. Tortola

In this paper we use solar neutrino data to derive stringent bounds on Majorana neutrino transition moments (TMs). Should such be present, they would contribute to the neutrino--electron scattering cross section and hence alter the signal observed in Super-Kamiokande. Motivated by the growing robustness of the LMA-MSW solution of the solar neutrino problem i

M. J. Duff

The possible time variation of dimensionless fundamental constants of nature, such as the fine-structure constant $α$, is a legitimate subject of physical enquiry. By contrast, the time variation of dimensional constants, such as $\hbar$, $c$, $G$, $e$, $k$,... which are merely human constructs whose number and values differ from one choice of units to the n

J. Bartels, D. Colferai, S. Gieseke, A. Kyrieleis

In this third part of our calculation of the QCD NLO corrections to the photon impact factor we combine our previous results for the real corrections with the singular pieces of the virtual corrections and present finite analytic expressions for the quark-antiquark-gluon intermediate state inside the photon impact factor. We begin with a list of the infrared

Weonjong Lee, Stephen R. Sharpe

We calculate one-loop matching factors for bilinear operators composed of improved staggered fermions. We compare the results for different improvement schemes used in the recent literature, all of which involve the use of smeared links. These schemes aim to reduce, though not completely eliminate, O(a^2) discretization errors. We find that all these improve

Kang Li

By using the two 4-dimensional potential formulation of electromagnetic (EM) field theory introduced in [1], we found that the SO(2) duality symmetric EM field theory can be reduced to the magnetic source free case by a special choice of SO(2) parameter,this special case we called nature picture of the EM field theory, the reduction condition led to a result

D. Bar

The effects of the experiment itself upon the obtained results and, especially, the influence of a large number of experiments are extensively discussed in the literature. We show that the important factor that stands at the basis of these effects is that the involved experiments are related and not independent and detached from each other. This relationship