March 2001 arXiv papers — page 5

L. S. Schulman

Under unitary evolution, systems move gradually from state to state. An unstable atom has amplitude in its original state after many lifetimes ($τ_L$). But in the laboratory, transitions seem to go instantaneously, as suggested by the term "quantum jump." The problem studied here is whether the "jump" can be assigned a duration, in theory and

V. M. Chabanov, B. N. Zakhariev

The possibility of the resonance reflection (100 % at maximum) is revealed. The corresponding exactly solvable models with the controllable numbers of resonances, their positions and widths are presented.

John V. Corbett, Dipankar Home

A tripartite system with entangled non-orthogonal states is used to transfer retrievable or usable information without requiring an external channel, ipso-information-transfer (IIT). The non-Schmidt decomposable entanglement couples two independent interactions through which the information is transferred between a pair of non-interacting components of the s

G. D. Lewen, W. Bialek, R. R. de Ruyter van Steveninck

We study a wide field motion sensitive neuron in the visual system of the blowfly {\em Calliphora vicina}. By rotating the fly on a stepper motor outside in a wooded area, and along an angular motion trajectory representative of natural flight, we stimulate the fly's visual system with input that approaches the natural situation. The neural response is a

D. Mulhall, V. Zelevinsky, A. Volya

Recent developments in many-body quantum chaos have raised the issue of correlations between different families of levels in the spectra of random fermionic systems. It seems that rotational invariance is sufficient to force an otherwise random system to have statistically ordered spectra where the ground state can have zero spin or the maximum spin allowed

N. Itaco, A. Covello, A. Gargano

We have investigated the effects of the neutron-proton interaction in several doubly odd deformed nuclei within the framework of the particle-rotor model. In this paper, we show some selected results of our study which evidence the importance of the tensor-force effects.

J. P. Draayer, G. Popa, J. G. Hirsch

Energy levels of the four lowest bands in 160,162,164Dy and 168Er, B(E2) transition strengths between the levels, and the B(M1) strength distribution of the ground state, all calculated within the framework of pseudo-SU(3) model, are presented. Realistic single-particle energies and quadrupole-quadrupole and pairing interaction strengths fixed from systemati

Marek Gazdzicki, Stanislaw Mrowczynski

Charge fluctuations studied on event-by-event basis have been recently suggested to provide a signal of the equilibrium quark-gluon plasma produced in heavy-ion collisions at high energies. It is argued that the fluctuations generated at the early collision stage when the energy is released can fake the signal.

Luca Degiovanni, Franco Magri, Vincenzo Sciacca

We study a class of deformations of infinite-dimensional Poisson manifolds of hydrodynamic type which are of interest in the theory of Frobenius manifolds. We prove two results. First, we show that the second cohomology group of these manifolds, in the Poisson-Lichnerowicz cohomology, is ``essentially'' trivial. Then, we prove a conjecture of B. Dubr

J. A. Zagrodzinski, T. Nikiciuk

The addition relation for the Riemann theta functions and for its limits, which lead to the appearance of exponential functions in soliton type equations is discussed. The presented form of addition property resolves itself to the factorization of N-tuple product of the shifted functions and it seems to be useful for analysis of soliton type continuous and d

Zakaria Giunashvili

We study variuos homological structures associated with Poisson algebra, the canonical differential complex for singular Poisson structure and the analogue of the star operator for such manifolds. Give the interpretation of the classical Koszul differential of exterior forms, as the supercommutator with some second order element. Describe the space of invari

Fabien Besnard

It is well known that the Lie-algebra structure on quantum algebras gives rise to a Poisson-algebra structure on classical algebras as the Planck constant goes to 0. We show that this correspondance still holds in the generalization of super- algebra introduced by Scheunert, called epsilon-algebra. We illustrate this with the example of Number Operator Algeb

Juan C. Migliore, Uwe Nagel

It is well known that for a subscheme $V$ in ${\mathbb P}^{n}$ of codimension two, the conditions (1) $V$ is ACM, and (2) $V$ is "licci" (i.e. $V$ is in the liaison class of a complete intersection) are equivalent. In higher codimension, (2) implies (1) but the converse is false. For Gorenstein liaison the analog of (2) is: $(2')$ $V$ is "gli

R. M. Asherova, Yu. F. Smirnov, V. N. Tolstoy

We present the projection operator method in combination with the Wigner-Racah calculus of the subalgebra U_q(su(2)) for calculation of Clebsch-Gordan coefficients (CGCs) of the quantum algebra U_q(su(3)). The key formulas of the method are couplings of the tensor and projection operators and also a tensor form for the projection operator of U_q(su(3)). We o

Igor V. Dolgachev, Jonghae Keum

We find generators of the group of birational automorphisms of the Hessian surface of a general cubic surface. Its nonsingular minimal model is a K3 surface with the Picard lattice of rank 16. The latter embeds naturally in the even unimodular lattice $II^{1,25}$ of rank 26 and signature $(1,25)$ as the orthogonal complement of a root sublattice of rank 10.

Valentin Deaconu, Paul S. Muhly

In this note we analyze the C*-algebra associated with a branched covering both as a groupoid C*-algebra and as a Cuntz-Pimsner algebra. We determine conditions when the algebra is simple and purely infinite. We indicate how to compute the K-theory of several examples, including one related to rational maps on the Riemann sphere.

Raimundas Vidunas, Nico M. Temme

Computer algebra algorithms are developed for evaluating the coefficients in Airy-type asymptotic expansions that are obtained from integrals with a large parameter. The coefficients are defined from recursive schemes obtained from integration by parts. An application is given for the Weber parabolic cylinder function.

Jean-Christophe Aval, Francois Bergeron, Nantel Bergeron

The space $M_{μ/i,j}$ spanned by all partial derivatives of the lattice polynomial $Δ_{μ/i,j}(X;Y)$ is investigated in math.CO/9809126 and many conjectures are given. Here, we prove all these conjectures for the $Y$-free component $M_{μ/i,j}^0$ of $M_{μ/i,j}$. In particular, we give an explicit bases for $M_{μ/i,j}^0$ which allow us to prove directly the cen

A. Raouf Chouikha

We interest in the behaviour of the period function for equations of the type $u'' + g(u) = 0$ and $u'' + f(u)u' + g(u) = 0$ with a center at the origin 0. $g$ is a function of class $C^k$. For the conservative case, if $k \geq 2$ one shows that the Opial criterion is the better one among those for which these the necessary condition $g&#

L. Barbieri-Viale

The goal of this paper is to introduce Hodge 1-motives of algebraic varieties and to state a corresponding cohomological Grothendieck-Hodge conjecture, generalizing the classical Hodge conjecture to arbitrarily singular proper schemes.

Anna Erschler-Dyubina

We estimate growth rates for small cancellation groups. In particular we show that there is a continuum possible values for exponential growth rates.

Hirotaka Tamanoi

We introduce the notion of generalized orbifold Euler characteristic associated to an arbitrary group, and study its properties. We then calculate generating functions of higher order (p-primary) orbifold Euler characteristic of symmetric products of a G-manifold M. As a corollary, we obtain a formula for the number of conjugacy classes of d-tuples of mutual

H. Endo, M. Korkmaz, D. Kotschick, B. Ozbagci

We construct examples of Lefschetz fibrations with prescribed singular fibers. By taking differences of pairs of such fibrations with the same singular fibers, we obtain new examples of surface bundles over surfaces with non-zero signature. From these we derive new upper bounds for the minimal genus of a surface representing a given element in the second hom

Jason Fulman

First we survey generating function methods for obtaining useful probability estimates about random matrices in the finite classical groups. Then we describe a probabilistic picture of conjugacy classes which is coherent and beautiful. Connections are made with symmetric function theory, Markov chains, potential theory, Rogers-Ramanujan type identities, quiv

Ashok Das, J. Maharana, A. Melikyan

We study the dynamics of an open membrane with a cylindrical topology, in the background of a constant three form, whose boundary is attached to p-branes. The boundary closed string is coupled to a two form potential to ensure gauge invariance. We use the action, due to Bergshoeff, London and Townsend, to study the noncommutativity properties of the boundary

Carl E. Dolby, Stephen F. Gull

A reformulation of fermionic QFT in electromagnetic backgrounds is presented which uses methods analogous to those of conventional multiparticle quantum mechanics. Emphasis is placed on the (Schrödinger picture) states of the system, described in terms of Slater determinants of Dirac states, and not on the field operator $\hatψ(x)$ (which is superfluous in t

Akira Kokado, Gaku Konisi, Takesi Saito

We construct a vertex operator which describes an emission of the ground-state tachyon of the closed string out of the noncommutative open string. Such a vertex operator is shown to exist only when the momentum of the closed-string tachyon is subject to some constraints coming from the background $B$ field. The vertex operator has a multiplicative coupling c

Adrian Dumitru, Miklos Gyulassy

The evolution of the gluon plasma produced with saturation initial conditions is calculated via Boltzmann transport theory for nuclear collisions at high energy. The saturation scale increases with the nuclear size and the beam energy, and thus we find that the perturbative rescattering rate decreases relative to the initial longitudinal expansion rate of th

Ulrich Loering, Bernard Ch. Metsch, Herbert R. Petry

This is the third of a series of papers treating light baryon resonances up to 3 GeV within a relativistically covariant quark model based on the Bethe-Salpeter equation with instantaneous two- and three-body forces. In this last paper we extend our previous work on non-strange baryons to a prediction of the complete strange baryon spectrum and a detailed co

Ulrich Loering, Bernard Ch. Metsch, Herbert R. Petry

This is the second of a series of three papers treating light baryon resonances up to 3 GeV within a relativistically covariant quark model based on the three-fermion Bethe-Salpeter equation with instantaneous two- and three-body forces. In this paper we apply the covariant Salpeter framework (which we developed in the first paper) to specific quark model ca

John Ellis

After recalling the motivations for expecting supersymmetry to appear at energies below 1 TeV, the reasons why the lightest supersymmetric particle is an ideal candidate for cold dark matter are reviewed from a historical perspective. Recent calculations of the relic density including coannihilations and rapid annihilations through direct-channel Higgs boson

Ulrich Loering, Klaus Kretzschmar, Bernard Ch. Metsch, Herbert R. Petry

This is the first of a series of three papers treating light baryon resonances (up to 3 GeV) within a relativistically covariant quark model based on the three-fermion Bethe-Salpeter equation with instantaneous two- and three-body forces. In this paper we give a unified description of the theoretical background and demonstrate how to solve the Bethe-Salpeter

Andre Martin, Jean-Marc Richard

We re-examine V. Gribov's theorem of 1960 according to which the total cross-section cannot approach a finite non-zero limit with, at the same time, a diffraction peak having a finite slope. We are very close to proving by an explicit counter-example that elastic unitarity in the elastic region is an essential ingredient of the proof. By analogy, we rais

Per Osland, Tai Tsun Wu

We review recent work on analytical solutions to the MSW equations for three neutrino flavours, for exponential and linear potentials. An application to a particular mass matrix is also discussed. The three neutrino masses are determined, respectively, to be 0.001--0.004, and roughly 0.01 and 0.05 eV.

A. V. Anisovich, V. V. Anisovich, V. A. Nikonov

Partial widths of the radiative decays $ϕ(1020)\toγf_0(980)$, $γη$, $γη'$, $γπ^0$ and $f_0(980)\toγγ$ are calculated assuming all mesons under consideration to be $q\bar q$ states: $ϕ(1020)$ is dominantly an $s\bar s$ state ($n\bar n$ component $\lesssim 1%$), $η$, $η'$ and $π^0$ are standard $q\bar q$ states, $η= n\bar n\cosθ- s\bar s\sinθ$ and $η&#

The OPAL collaboration, G. Abbiendi

Measurements of the tau lepton polarization and forward-backward polarization asymmetry near the Z resonance using the OPAL detector are described. The measurements are based on analyses of tau -> e nu_e nu_tau, tau -> mu nu_mu nu_tau, tau -> pi nu_tau, tau -> rho nu_tau and tau -> a1 nu_tau decays from a sample of 144810 e+e- -> tau+ tau- candidates corresp

Bernard Kelly, Pablo Laguna, Keith Lockitch, Jorge Pullin

Numerical codes based on a direct implementation of the standard ADM formulation of Einstein's equations have generally failed to provide long-term stable and convergent evolutions of black hole spacetimes when excision is used to remove the singularities. We show that, for the case of a single black hole in spherical symmetry, it is possible to circumve

A. A. Sen, S. Sen

We have investigated the cosmological scenarios with a four dimensional effective action which is connected with multidimensional, supergravity and string theories. The solution for the scale factor is such that initially universe undergoes a decelerated expansion but in late times it enters into the accelerated expansion phase. Infact, it asymptotically bec

B. V. Ivanov

New expanding, axisymmetric pure-radiation solutions are found, exploiting the analogy with the Euler-Darboux equation for aligned colliding plane waves.

B. V. Ivanov

Pure-radiation solutions are found, exploiting the analogy with the Euler- Darboux equation for aligned colliding plane waves and the Euler-Tricomi equation in hydrodynamics of two-dimensional flow. They do not depend on one of the spacelike coordinates and comprise the Hauser solution as a special subcase.

B. V. Ivanov

The system of Einstein-Maxwell equations for fields mentioned in the title is simplified. Known pure radiation solutions are systematized and new solutions are given by separating the variables.

V. R. Gavrilov, V. N. Melnikov

D-dimensional cosmological model describing the evolution of a perfect fluid with negative pressure (x-fluid) and a fluid possessing both shear and bulk viscosity in n Ricci-flat spaces is investigated. The second equations of state are chosen in some special form of metric dependence of the shear and bulk viscosity coefficients. The equations of motion are

Nir Friedman, Joseph Y. Halpern

We examine carefully the rationale underlying the approaches to belief change taken in the literature, and highlight what we view as methodological problems. We argue that to study belief change carefully, we must be quite explicit about the ``ontology'' or scenario underlying the belief change process. This is something that has been missing in prev

Francis Chu, Joseph Y. Halpern

Consider a very simple class of (finite) games: after an initial move by nature, each player makes one move. Moreover, the players have common interests: at each node, all the players get the same payoff. We show that the problem of determining whether there exists a joint strategy where each player has an expected payoff of at least r is NP-complete as a fu

Amy Y. Liu, I. I. Mazin, Jens Kortus

Density-functional calculations of the phonon spectrum and electron-phonon coupling in MgB$_2$ are presented. The $E_{2g}$ phonons, which involve in-plane B displacements, couple strongly to the $p_{x,y}$ electronic bands. The isotropic electron-phonon coupling constant is calculated to be about 0.8. Allowing for different order parameters in different bands

M. Paranthaman, C. Cantoni, H. Y. Zhai, H. M. Christen

Superconducting MgB(2) films with Tc = 38.6 K were prepared using a precursor-deposition, ex-situ post-processing approach. Precursor films of boron, ~0.5 micrometer thick, were deposited onto Al(2)O(3) (102) substrates by e-beam evaporation; a post-anneal at 890 deg C in the presence of bulk MgB(2) and Mg metal produced highly crystalline MgB(2) films. X-ra

L. Ottaviano, G. Profeta, L. Petaccia, C. Nacci

Direct comparison of scanning tunneling microscopy and high resolution core level photo-emission experiments provides a rationale for the mechanism of formation of a two dimensional (2D) binary alloy (1/3 mono-layer (ML) Sn(1- x)Six/Si(111)-\sqrt3X\sqrt3R30). In contrast with recent theoretical predictions, the pure metal surface (x=0) results partitioned in

J. Batle, M. Casas M. Fortes, M. A. Solís, M. de Llano

Cooper pair (CP) binding with both zero and nonzero center-of-mass momenta (CMM) is studied with a set of renormalized equations assuming a short-ranged (attractive) pairwise interfermion interaction. Expanding the associated dispersion relation in 2D in powers of the CMM, in weak-to-moderate coupling a term {\it linear} in the CMM dominates the pair excitat

K V Tabunshchyk

A method of consideration of gaussian fluctuations of the effective mean field within the framework of the GRPA scheme is applied to investigation of thermodynamical properties of a pseudospin-electron model (PEM). The grand canonical potential, pseudospin mean value, as well as the mean squares of fluctuations are calculated. Obtained results are compared w

Sadhan K. Adhikari

We present a numerical study of the coupled time-dependent Gross-Pitaevskii equation, which describes the Bose-Einstein condensate of several types of trapped bosons at ultralow temperature with both attractive and repulsive interatomic interactions. The same approach is used to study both stationary and time-evolution problems. We consider up to four types

G. Yusa, H. Shtrikman, I. Bar-Joseph

We study the photoluminescence spectrum of a low density ($ν<1$) two-dimensional electron gas at high magnetic fields and low temperatures. We find that the spectrum in the fractional quantum Hall regime can be understood in terms of singlet and triplet charged-excitons. We show that these spectral lines are sensitive probes for the electrons compressibility

F. Buyukkilic, H. Uncu, D. Demirhan

In this study, The particles of the quantum gases, namely bosons and fermions are regarded as g-ons by the paremeter of the fractional exclusion statistics g. With this point of departure, the distribution function of the g-on gas is obtained by the variational, steepest descent and statistical methods. The distribution functions which are found by means of

Sze-Shiang Feng, Bin Wang, Elcio Abdalla

By acting on the excited states at half-filling in the positive-$U$ Hubbard model with the $η$-pairing operators, we found some new superconducting states in the Hubbard model away from half-filling. Such eigenstates are different from the zero-pair and one-pair states introduced by Yang. It is shown that the one-pair states are not the ground-states and pos

S. Bellucci, J. Gonzalez

We study graphene-based electron systems with long-range Coulomb interaction by performing an analytic continuation in the number of dimensions. We characterize in this way the crossover between the marginal Fermi liquid behavior of a graphite layer and the Luttinger liquid behavior at $D = 1$. The former persists for any dimension above $D = 1$. However, th

Daniel M. Mueth

Experimental measurements of particle dynamics on the lower surface of a 3D Couette cell containing monodisperse spheres are reported. The average radial density and velocity profiles are similar to those previously measured within the bulk and on the lower surface of the 3D cell filled with mustard seeds. Observations of the evolution of particle velocities

Barry M. McCoy

I use recent advances in the study of the susceptibility of the Ising model to propose a new mechanism for the freezing transition which is observed in three dimensional hard spheres.

Enrico Celeghini, Mario Rasetti

A quantitative analysis of the process of condensation of bosons both in harmonic traps and in gases is made resorting to two ingredients only: Bose classical distribution and spectral discretness. It is shown that in order to take properly into account statistical correlations, temperature must be defined from first principles, based on Shannon entropy, and

V. I. Yukalov

An ensemble of resonance atoms is considered, which are doped into a medium with well developed polariton effect, when in the spectrum of polariton states there is a band gap. If an atom with a resonance frequency inside the polariton gap is placed into the medium, the atomic spontaneous emission is suppressed. However, a system of resonance atoms inside the

Masamichi Nishino, Keiji Saito, Seiji Miyashita

We study effect of noise on the tunneling process of the magnetization in a sweeping field from the viewpoint of the nonadiabatic transition. The tunneling probability depends on the properties of the noise, e.g. the direction, the amplitude, and the relaxation time of the autocorrelation function. We investigate the tunneling process in the presence of nois

A. S. Mishchenko, N. Nagaosa

The self-trapping by the nondiagonal particle-phonon interaction between two quasi-degenerate energy levels of excitonic system, is studied. We propose this is realized in charge transfer exciton, where the directions of the polarization give the quasi-degeneracy. It is shown that this mechanism, unlike the conventional diagonal one, allows a coexistence and

Yu Zhu, Qing-feng Sun, Tsung-han Lin

We study Andreev bound states and $π$-junction transition in a superconductor / quantum-dot / superconductor (S-QD-S) system by Green function method. We derive an equation to describe the Andreev bound states in S-QD-S system, and provide a unified understanding of the $π$-junction transition caused by three different mechanisms: (1) {\it Zeeman splitting.}

F. Buyukkilic, I. Sokmen, D. Demirhan

Thermodynamical quantities of the blackbody radiation, such as free energy, entropy, total radiation energy, specific heat are calculated within the Tsallis thermostatistics where factorization method is incorparated. It is shown that basic thermodynamical relation of the blackbody radiation is form invariant with respect to nonextensivity entropic index q.

David E. Trilling, David W. Koerner, Jason W. Barnes, Christ Ftaclas

We present ground-based near-infrared (H-band) imaging of the circumstellar disk around the nearby classical T Tauri star TW Hydrae. The scattered light image shows a face-on disk with radius 4 arcseconds (corresponding to 225 AU) and a morphology which agrees with recent images from the Hubble Space Telescope and the Very Large Array. The best fit power-law

J. Zzimbe

It is only human nature to be reluctant to accept something new and different. This feeling is exacerbated given the success of the Big Bang model. However, there are cogent reasons for considering this new model. Some of the advantages of this new model over the existing Big Bang model are as follows: (1) It does not violate any known laws of physics. This

Liese van Zee, John J. Salzer, Evan D. Skillman

We present the results of high spatial resolution HI synthesis observations of six blue compact dwarf (BCD) galaxies. Optically, the selected galaxies have smooth, symmetric isophotes, and thus are the most likely of the BCD class to fade into an object morphologically similar to a dwarf elliptical when the current starburst ends. The neutral gas in all six

Charles W. Danforth, You-Hua Chu

New observations of the Magellanic Cloud Luminous Blue Variable candidate S119 (HD269687) show the relationship of the star to its environs. Echelle spectroscopy and high-resolution HST imagery reveal an expanding bubble centered on the star. This bubble appears in both Halpha and [NII] and is noticeably brighter on the near (blue-shifted) side. The systemic

R. Bacon, Y. Copin, G. Monnet, Bryan W. Miller

A new integral-field spectrograph, SAURON, is described. It is based on the Tiger principle, and uses a lenslet array. SAURON has a large field of view and high throughput, and allows simultaneous sky subtraction. Its design is optimized for studies of the stellar kinematics, gas kinematics, and line-strength distributions of nearby early-type galaxies. The

A. A. Breeveld, E. M. Puchnarewicz, C. Otani

We present ASCA data on RE J2248-511, extending existing optical and soft X-ray coverage to 10 keV, and monitoring the soft component. These data show that, despite a very strong ultrasoft X-ray excess below 0.3 keV and a soft 0.3--2 keV spectral index in earlier ROSAT data, the hard X-ray spectrum (alpha~ -0.8; 0.6-10 keV) is typical of type 1 AGN, and the

V. Filinov, M. Bonitz, D. Kremp, W. -D. Kraeft

The results of analytical approximations and extensive calculations based on a path integral Monte Carlo (PIMC) scheme are presented. A new (direct) PIMC method allows for a correct determination of thermodynamic properties such as energy and equation of state of dense degenerate Coulomb systems. In this paper, we present results for dense partially ionized

Duccio Fanelli, Marco Merafina, Stefano Ruffo

We introduce a one-dimensional toy model of globular clusters. The model is a version of the well-known gravitational sheets system, where we take additionally into account mass and energy loss by evaporation of stars at the boundaries. Numerical integration by the &#34;exact&#34; event-driven dynamics is performed, for initial uniform density and Gaussian r

T. P. Krichbaum, A. Witzel, J. A. Zensus

We monitored 3C273 with VLBI at 15-86 GHz since 1990. We discuss component trajectories, opacity effects at the jet base, a rotating and perhaps precessing jet, and outburst-ejection relations from Gamma-ray to radio bands.

T. P. Krichbaum, D. A. Graham, A. Witzel, J. A. Zensus

We show results from a 7 year VLBI monitoring programme of 3C273 at millimeter wavelengths. We find evidence for component acceleration, motion or rotation of fluid dynamical patterns in the VLBI jet, and evidence for an outburst-ejection relation between Gamma-ray flares and the appearance of new jet components.

K. G. Noeske, J. Iglesias-Paramo, J. M. Vilchez, P. Papaderos

We have searched for companion galaxies in the close environment of 98 star-forming dwarf galaxies (SFDGs) from field and low density environments, using the NASA Extragalactic Database. Most of the companions are dwarf galaxies which due to observational selection effects were previously disregarded in environmental studies of SFDGs. A subsample at low reds

B. J. Mochejska, J. Kaluzny, K. Z. Stanek, D. D. Sasselov

DIRECT is a project to directly obtain the distances to two important galaxies in the cosmological distance ladder, M31 and M33, using detached eclipsing binaries and Cepheids. As part of our search for these variables, we have obtained photometry and positions for thousands of stellar objects within the monitored fields, covering an area of 557.8 arcmin^2.

B. J. Mochejska, L. M. Macri, D. D. Sasselov, K. Z. Stanek

We investigate the influence of blending on the Cepheid distance scale. Blending is the close association of a Cepheid with one or more intrinsically luminous stars. High-resolution HST images are compared to our ground-based data, obtained as part of the DIRECT project, for a sample of 102 Cepheids in the M33 galaxy. The average (median) flux contribution f

A. C. Fabian

Deep observations of the X-ray Sky have now resolved most of the X-ray Background. Obscured active galaxies are a key component. The obscured objects which dominate at fluxes above $10^{-15}\ergpcmsqps$ are discussed and models in which the growth of wind-blowing active nuclei determine both black hole and galaxy mass are presented. The power from accretion

A. C. Fabian

The observations and interpretation of broad iron lines in the X-ray spectra of Seyfert 1 galaxies are reviewed. The line profiles observed from MCG--6-30-15 and NGC 3516 show extended red wings to the line explained by large gravitational redshifts. The results are consistent with the emission expected from an X-ray irradiated flat accretion disc orbiting v

Neal Dalal, Kim Griest, Jason Pruet

If gamma-ray burst (GRB) emission is strongly collimated then GRBs occur throughout the Universe at a rate much higher than is detected. Since the emission from the optical afterglow is thought to be more isotropic than the gamma-ray emission, it has been hypothesized that a search for orphan afterglows (those without the triggering GRB) would allow strong c

B. Gladman, M. Holman, T. Grav, J. Kavelaars

By telescopic tracking, we have established that the orbit of the trans-neptunian object (2000 CR$_{105}$) has a perihelion of $\simeq$44 AU, and is thus outside the domain controlled by strong gravitational close encounters with Neptune. Because this object is on a very large, eccentric orbit (with semimajor axis $a\simeq$216 AU and eccentricity $e\simeq$0.

Herve Dole, Richard Gispert, Guilaine Lagache, Jean-Loup Puget

The FIRBACK (Far Infrared BACKground) survey is one of the deepest imaging surveys carried out at 170 microns with ISOPHOT onboard ISO, and is aimed at the study of the structure of the Cosmic Far Infrared Background. This paper provides the analysis of resolved sources. After a validated process of data reduction and calibration, we perform intensive simula

Guilaine Lagache, Herve Dole

We present the final reduction and calibration of the FIRBACK ISOPHOT data. FIRBACK is a deep cosmological survey performed at 170 microns. This paper deals with the ISOPHOT C200 camera with the C160 filter. We review the whole data reduction process and compare our final calibration with DIRBE (for the extended emission) and IRAS (for point sources). The FI

C. A. Tremonti, D. Calzetti, C. Leitherer, T. M. Heckman

We investigate the star formation history of both the bright star clusters and the diffuse `field star&#39; population in the dwarf starburst galaxy NGC 5253 using STIS longslit ultraviolet spectroscopy. Our slit covers a physical area of 370 x 1.6 pc and includes 8 apparent clusters and several inter-cluster regions of diffuse light which we take to be the

R. A. Remillard

Recent X-ray timing and spectral observations of black hole binaries in outburst have redefined methods for investigating the properties of Galactic black holes and the physics of accretion flows. High-frequency X-ray QPOs in 5 systems (60--300 Hz) continue to be investigated as a possible means to constrain black hole mass and spin via interpretation as osc

Lucio Mayer, Fabio Governato, Monica Colpi, Ben Moore

We present results from high-resolution N-Body/SPH simulations of rotationally supported dwarf irregular galaxies moving on bound orbits in the massive dark matter halo of the Milky Way.The dwarf models span a range in disk surface density and the masses and sizes of their dark halos are consistent with the predictions of cold dark matter cosmogonies. We sho

Pavel Kroupa, Andreas Burkert

Pre-main sequence and main-sequence binary systems are observed to have periods, P, ranging from one day to 10^(10) days and eccentricities, e, ranging from 0 to 1. We pose the problem if stellar-dynamical interactions in very young and compact star clusters may broaden an initially narrow period distribution to the observed width. N-body computations of ext

H. Pierre Noyes

A decade ago bit-string physics predicted that the baryon/photon ratio at the time of nucleogenesis $η= 1/256^4$ and that the dark matter/baryonic matter ratio $Ω_{DM}/Ω_B= 12.7$. Accepting that the normalized Hubble constant is constrained observationally to lie in the range $0.6 < h_0 < 0.8$, this translates into a prediction that $0.325 > Ω_M > 0.183 $. T

Shamit Kachru, John McGreevy

We demonstrate that M-theory compactifications on 7-manifolds of G_2 holonomy, which yield 4d N=1 supersymmetric systems, often admit at special loci in their moduli space a description as type IIA orientifolds. In this way, we are able to find new dualities of special IIA orientifolds, including dualities which relate orientifolds of IIA strings on manifold

Alexei Yung

We study Abrikosov-Nielsen-Olesen (ANO) flux tubes on the Higgs branch of N=2 QCD with SU(2) gauge group and two flavors of fundamental matter. In particular, we consider this theory near Argyres-Douglas (AD) point where the mass of monopoles connected by these ANO strings becomes small. In this regime the effective QED which describes the theory on the Higg

Gregory Leibon

Given a Delaunay decomposition of a compact hyperbolic surface, one may record the topological data of the decomposition, together with the intersection angles between the `empty disks&#39; circumscribing the regions of the decomposition. The main result of this paper is a characterization of when a given topological decomposition and angle assignment can be

Allan Adams, Eva Silverstein

We find that tachyonic orbifold examples of AdS/CFT have corresponding instabilities at small radius, and can decay to more generic gauge theories. We do this by computing a destabilizing Coleman-Weinberg effective potential for twisted operators of the corresponding quiver gauge theories, generalizing calculations of Tseytlin and Zarembo and interpreting th

Johanna Erdmenger

A quantum-field theoretical interpretation is given to the holographic RG equation by relating it to a field-theoretical local RG equation which determines how Weyl invariance is broken in a quantized field theory. Using this approach we determine the relation between the holographic C theorem and the C theorem in two-dimensional quantum field theory which r

Ralf Hofmann

Based on general renormalization group arguments, Polyakov&#39;s loop-space formalism, and recent analytical lattice arguments, suggesting, after Abelian gauge fixing, a description of pure gluodynamics by means of a Georgi-Glashow like model, the corresponding vacuum fields are defined in a non-local way. Using lattice information on the gauge invariant fie

Mark G. Jackson

We determine the stability conditions for a radially symmetric noncommutative scalar soliton at finite noncommutivity parameter $\theta$. We find an intriguing relationship between the stability and existence conditions for all level-1 solutions, in that they all have nearly-vanishing stability eigenvalues at critical $\theta m^2$. The stability or non-stabi

T. W. Murphy, B. T. Soifer, K. Matthews, L. Armus

Imaging spectroscopy using the new Palomar Integral Field Spectrograph is presented for the Pa-alpha line in four ultraluminous infrared galaxies. In most cases, we are able to establish the geometry of the merger, and thus estimate the time in the merger process at which we are viewing the system. The resulting range in estimated ages, some of which are ver

Christopher D. Sogge, Steve Zelditch

On any compact Riemannian manifold $(M, g)$ of dimension $n$, the $L^2$-normalized eigenfunctions $\{ϕ_λ\}$ satisfy $||ϕ_λ||_{\infty} \leq C λ^{\frac{n-1}{2}}$ where $-Δϕ_λ = λ^2 ϕ_λ.$ The bound is sharp in the class of all $(M, g)$ since it is obtained by zonal spherical harmonics on the standard $n$-sphere $S^n$. But of course, it is not sharp for many Rie

A. Hasenfratz, F. Knechtli

We introduce a new smearing transformation, the hypercubic (HYP) fat link. The hypercubic fat link mixes gauge links within hypercubes attached to the original link only. Using quenched lattices at beta = 5.7 and 6.0 we show that HYP fat links improve flavor symmetry by an order of magnitude relative to the thin link staggered action. The static potential me

Adrian Dragulescu, Victor M. Yakovenko

We present the data on wealth and income distributions in the United Kingdom, as well as on the income distributions in the individual states of the USA. In all of these data, we find that the great majority of population is described by an exponential distribution, whereas the high-end tail follows a power law. The distributions are characterized by a dimen

Andrew S. Ackerman, Mark S. Marley

We present a method to calculate vertical profiles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent diffusion and sedimentation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with results from previous methods. An adjustable par

V. M. Braun, D. Yu. Ivanov, A. Schaefer, L. Szymanowski

We calculate the cross section of a pion diffraction dissociation in two jets with large transverse momenta originating from a hard gluon exchange between the pion constituents. To the leading logarithmic accuracy (in energy), the contribution coming from small transverse separations between the quark and the antiquark in the pion acquires the expected facto

V. Latora, A. Rapisarda, C. Tsallis

We study the dynamics of a system of N classical spins with infinite-range interaction. We show that, when the thermodynamic limit is taken before the infinite-time limit, the system does not relax to the Boltzmann-Gibbs equilibrium, but exhibits different equilibrium properties, characterized by stable non-Gaussian velocity distributions and dynamical power