November 2000 arXiv papers — page 4

Hongsu Kim, Hyun Kyu Lee, Chul H. Lee

In this work, the interaction of electromagnetic fields with a rotating (Kerr) black hole is explored in the context of Born-Infeld (BI) theory of electromagnetism instead of standard Maxwell theory and particularly BI theory versions of the four horizon boundary conditions of Znajek and Damour are derived. Naturally, an issue to be addressed is then whether

B. Cessac, Ph. Blanchard, T. Krueger

We discuss the role played by the Lyapunov exponents in the dynamics of Zhang's model of Self-Organized Criticality. We show that a large part of the spectrum (slowest modes) is associated with the energy transpor in the lattice. In particular, we give bounds on the first negative Lyapunov exponent in terms of the energy flux dissipated at the boundaries

Zurab Kakushadze, Peter Langfelder

We discuss the gravitational Higgs mechanism in domain wall background solutions that arise in the theory of 5-dimensional Einstein-Hilbert gravity coupled to a scalar field with a non-trivial potential. The scalar fluctuations in such backgrounds can be completely gauged away, and so can be the graviphoton fluctuations. On the other hand, we show that the g

Sang-Hyeon Ahn, Hee-Won Lee, Hyung Mok Lee

We investigate the Lyman alpha line transfer in nearby and high redshift starbursting galaxies, where the effect of high optical depths and the role of dust in the scattering medium are expected to be conspicuous and should be treated in a very careful manner. We present our first results in dustless, static, and uniform HI media with moderate Lyman alpha li

X. -G. He, Y. -K. Hsiao, J. -Q. Shi, Y. -L. Wu

We study constraints on the CP violating phase $γ$ in the Kobayashi-Maskawa model using available experimental data. We first follow the conventional method to up date the constraint on $γ$ by performing a $χ^2$ analysis using data from $|ε_K|$, $Δm_{B_{d,s}}$ and $|V_{ub}/V_{cb}|$. We also include the recent information on $\sin2β$ in the analysis. We obtai

Yoram Lithwick, Re'em Sari

As is well-known, the requirement that gamma ray bursts (GRB's) be optically thin to high energy photons yields a lower limit on the Lorentz factor (γ) of the expansion. In this paper, we provide a simple derivation of the lower limit on γdue to the annihilation of photon pairs, and correct the errors in some of the previous calculations of this limit. W

C. P. Burgess, M. Pospelov, T. ter Veldhuis

We propose the simplest possible renormalizable extension of the Standard Model - the addition of just one singlet scalar field - as a minimalist model for non-baryonic dark matter. Such a model is characterized by only three parameters in addition to those already appearing within the Standard Model: a dimensionless self-coupling and a mass for the new scal

Dongsu Bak, Kimyeong Lee, Jeong-Hyuck Park

We study the gauge theories on noncommutative space. We employ the idea of the covariant position to understand the linear and angular momenta, the center of mass position, and to express all gauge invariant observables including the Wilson line. In addition, we utilize the universality of the U(1) gauge theory, which originates from the underlying matrix th

Frank Verstraete, Jeroen Dehaene, Bart De Moor

We consider one single copy of a mixed state of two qubits and investigate how its entanglement changes under local quantum operations and classical communications (LQCC) of the type $ρ'\sim (A\otimes B)ρ(A\otimes B)^{\dagger}$. We consider a real matrix parameterization of the set of density matrices and show that these LQCC operations correspond to lef

Shantilal G. Goradia

General Relativity makes a distinction between mass and space. Mass tells space how to curve and space tells mass how to move. Newtonian gravity equation makes a distinction between them by having its numerator as mass effect and its denominator as inverse square law space effect at macroscopic approximation. At microscopic distances it makes sense to substi

Thomas Gold

I think it important that pilots, the aircraft industry, air safety staff, accident investigators, should all be aware of the possibility of the hazard described in the accompanying article, and also that research shold be directed to establish the severity of this hazard, and find ways of diminishing the risk.

M. Savopulos, J. J. Quenby, M. K. Joshi, M. Fraenz

The first high solar latitude pass of the Ulysses spacecraft revealed the presence of MeV particle increases up to latitudes above 60 degrees, well outside the CIR belt but associated in time with the regular passage of these plasma interfaces at more equatorial latitudes. The particle increases have been explained variously as due to diffusion from a field

E. Garrido, D. V. Fedorov, A. S. Jensen

A theoretical model able to describe fragmentation reactions of three--body halo nuclei on different targets, from light to heavy, is used to compute neutron and core momentum distributions. Both Coulomb and nuclear interactions are simultaneously included. We specify the different reaction mechanisms related to various processes. The method is applied to fr

G. Garbarino

Two different approaches have been employed for the evaluation of the decay widths of Lambda-hypernuclei (ranging from $^5_Λ$He to $^{208}_Λ$Pb) with the polarization propagator method. In ref.[1], the two-nucleon stimulated non-mesonic decay, $ΛNN\to NNN$, has been parameterized phenomenologically by means of data on the pion-nucleus optical potential. The

M. C. Cross, M. Louie, D. Meiron

Numerical studies of the domain chaos state in a model of rotating Rayleigh-Benard convection suggest that finite size effects may account for the discrepancy between experimentally measured values of the correlation length and the predicted divergence near onset.

G. I. Barenblatt, A. J. Chorin, V. M. Prostokishin

A correlation is obtained for the drag coefficient $c '_f$ of the turbulent boundary layer as a function of the effective boundary layer Reynolds number $Re$ that we previously introduced. A comparison is performed also with another correlation for the drag coefficient as a function of the traditional Reynolds number $Re_þ$, based on the momentum thickne

T. Michoel, A. Verbeure

The imperfect Boson gas supplemented with a gentle repulsive interaction is completely solved. In particular it is proved that it has non-extensive Bose-Einstein condensation, i.e., there is condensation without macroscopic occupation of the ground state (k=0) level.

Takashi Hara, Remco van der Hofstad, Gordon Slade

We consider spread-out models of self-avoiding walk, bond percolation, lattice trees and bond lattice animals on the d-dimensional hyper cubic lattice having long finite-range connections, above their upper critical dimensions d=4 (self-avoiding walk), d=6 (percolation) and d=8 (trees and animals). The two-point functions for these models are respectively th

Frederick M. Goodman, Hans Wenzl

We develop an algorithm for computing affine Kazhdan-Lusztig polynomials, for all Lie types. This generalizes our previously published algorithm for type A, which in turn is a faster version of an algorithm due to Lascouz, Leclerc and Thibon (proposed in the setting of Hecke algebras of type A, at roots of unity.)

Michael Roitman

In this paper we classify, under certain restrictions, all homogeneous conformal subalgebras $\goth L$ of a lattice vertex superalgebra $V_Λ$ corresponding to an integer lattice $Λ$. We require that $\goth L$ is graded by an almost finite root system $Δ\subset Λ$ and that $\goth L$ is stable under the action of the Heisenberg conformal algebra $\goth H\subse

Domenico P. L. Castrigiano, Sandra A. Hayes

In this note we prove that whenever a Lie group $G$ acts on a manifold $X$, then the orbit $Gx$ through any point $x$ of $X$ is a weakly embedded submanifold of $X$. The investigation of this problem was inspired by an application to Cat astrophe Theory.

D. P. L. Castrigiano, W. Klopfer

Let a sequence $(P_n)$ of polynomials in one complex variable satisfy a recurre ce relation with length growing slowlier than linearly. It is shown that $(P_n) $ is an orthonormal basis in $L^2_μ$ for some measure $μ$ on $\C$, if and o ly if the recurrence is a $3-$term relation with special coefficients. The supp rt of $μ$ lies on a straight line. This resu

S. J. Dilworth, Ralph Howard, James W. Roberts

Let $n\ge1$ and $B\ge2$. A real-valued function $f$ defined on the $n$-simplex $Δ_n$ is approximately convex with respect to $Δ_{B-1}$ iff f(\sum_{i=1}^B t_ix_i) \le \sum_{i=1}^B t_if(x_i) +1 for all $x_1,...,x_B \in Δ_n$ and all $(t_1,...,t_B)\in Δ_{B-1}$. We determine explicitly the extremal (i.e. pointwise largest) function of this type which vanishes on

Mladen Bestvina, Mark Feighn

Every lattice H in a connected semi-simple Lie group G acts properly discontinuously by isometries on the contractible manifold G/K (K a maximal compact subgroup of G). We prove that if H acts on a contractible manifold W and if either 1) the action is properly discontinuous, or 2) W is equipped with a complete Riemannian metric, the action is by isometries

David Eisenbud, Sorin Popescu, Frank-Olaf Schreyer, Charles Walter

If r\geq 6, r\neq 9, we show that the Minimal Resolution Conjecture fails for a general set of m points in P^r for almost 1/2\sqrt r values of m. This strengthens the result of Eisenbud and Popescu [1999], who found a unique such m for each r in the given range. Our proof begins like a variation of that of Eisenbud and Popescu, but uses exterior algebra meth

Anders Claesson

Recently, Babson and Steingrimsson have introduced generalised permutation patterns that allow the requirement that two adjacent letters in a pattern must be adjacent in the permutation. We consider pattern avoidance for such patterns, and give a complete solution for the number of permutations avoiding any single pattern of length three with exactly one adj

Manoj K. Chari, Michael Joswig

We investigate properties of the set of discrete Morse functions on a simplicial complex as defined by Forman. It is not difficult to see that the pairings of discrete Morse functions of a finite simplicial complex again form a simplicial complex, the discrete Morse complex. It turns out that several known results from combinatorial topology and enumerative

Mircea Neagu

The paper construct a suitable generalized metrical multi-time Lagrange geometrical model for both gravitational and electromagnetic fields, in a general setting. In this construction, the gravitational potentials are described by a distinguished vertical metrical tensor of the form $h^{/alpha/beta}e^{2σ}/phi_{ij}$.

R. Vershynin

This paper addresses the problem of improving properties of a linear operator u in $l_2^n$ by restricting it onto coordinate subspaces. We discuss how to reduce the norm of u by a random coordinate restriction, how to approximate u by a random operator with small "coordinate" rank, how to find coordinate subspaces where u is an isomorphism. The first

Florin G. Radulescu

For an inclusion of the form $\Bbb C\subseteq M_n(\Bbb C)$, where $M_n(\Bbb C)$ is endowed with a state with diagonal weights $λ=(λ_1, ..., λ_n)$, we use Popa's construction, for non-tracial states, to obtain an irreducible inclusion of $II_1$ factors, $N^λ(Q)\subseteq M^λ(Q) $ of index $\sum \frac{1}{λ_i}$. $M^λ(Q)$ is identified with a subfactor inside

Margaret Cheney, David Isaacson, Matti Lassas

We consider the problem of obtaining information about an inaccessible half-space from acoustic measurements made in the accessible half-space. If the measurements are of limited precision, some scatterers will be undetectable because their scattered fields are below the precision of the measuring instrument. How can we make measurements that are optimal for

Alfred Scharff Goldhaber, Andrei Litvintsev, Peter van Nieuwenhuizen

To obtain the one-loop corrections to the mass of a kink by mode regularization, one may take one-half the result for the mass of a widely separated kink-antikink (or sphaleron) system, where the two bosonic zero modes count as two degrees of freedom, but the two fermionic zero modes as only one degree of freedom in the sums over modes. For a single kink, th

C. I. Lazaroiu

I use the universal instanton formalism to discuss quantum effects in the open-closed topological string theory of a Calabi-Yau A-model, in the presence of a multiply-wrapped `Floer' D-brane. This gives a precise meaning (up to the issue of compactifying the relevant moduli spaces) to the instanton corrections which affect sigma model and topological str

G. Modanese

Haisch and Rueda have recently proposed a model in which the inertia of charged particles is a consequence of their interaction with the electromagnetic zero-point field. This model is based on the observation that in an accelerated frame the momentum distribution of vacuum fluctuations is not isotropic. We analyze this issue through standard techniques of r

Thomas Strobl

PhD thesis TU-Vienna, May 1994. Table of Contents: 1. Introduction, 2. Poisson Structure Induced Two Dimensional Field Theories, 3. Models of Gravity in 1+1 Dimensions

J. Froehlich, P. A. Marchetti

We analyze previously proposed order parameters for the confinement - deconfinement transition in lattice SU(2) Yang-Mills theory, defined as vacuum expectation value (v.e.v.) of monopole fields in abelian projection gauges. We show that they exhibit some inconsistency in the treatment of small scales, due to a violation of Dirac quantization condition for f

Andrei Litvintsev, Peter van Nieuwenhuizen

We consider a new momentum cut-off scheme for sums over zero-point energies, containing an arbitrary function f(k) which interpolates smoothly between the zero-point energies of the modes around the kink and those in flat space. A term proportional to df(k)/dk modifies the result for the one-loop quantum mass M^(1) as obtained from naive momentum cut-off reg

E. Kh. Akhmedov

We review new results in neutrino physics, including the latest data of the Super-Kamiokande, SNO and K2K experiments.

J. C. Romao

The simplest unified extension of the Minimal Supersymmetric Standard Model with bi-linear R--Parity violation provides a predictive scheme for neutrino masses which can account for the observed atmospheric and solar neutrino anomalies. Despite the smallness of neutrino masses R-parity violation is observable at present and future high-energy colliders, prov

H. Mueller

Soft hadron production is described as a two-step process, where the interaction of the partonic constituents of the colliding hadrons leads to the production of intermediate subsystems (fireballs), which decay subsequently into hadrons. The weights of the various final states are derived from the corresponding phase-space factors modified by empirical trans

Gregory Mahlon

The weak decay of a polarized top quark has a rich structure of angular correlations among its decay products. We describe some of the noteworthy features of such decays. We then examine the three modes of single top production, with an emphasis on the status of calculations of the degree and direction of polarization at Run II of the Tevatron. The associate

Pankaj Agrawal

We carry out an event generator based study to evaluate the usefulness of the the exclusive signature ``$e^\pm (μ^\pm) + 2$ bottom jets'' in discovering the Higgs boson at the Tevatron. Using an event generator, we show that with enough luminosity, one should be able to detect the Higgs boson up to the mass of about 130 GeV. We consider a slightly mo

Pankaj Agrawal, Glenn Ladinsky

We have computed the cross-section and distributions for the production of two photons and a jet via the process $g g \to γγg$. In the Standard Model, this process occurs at the one-loop level through pentagon and box diagrams. We show that at the LHC this is a significant mechanism for the production of the two photons and a jet. This process is also an imp

H. Burkhardt, J. Lowe, G. Eilam, M. D. Scadron

We extract the K^+-->pi^+e^+e^- amplitude scale at q^2=0 from the recent Brookhaven E865 high-statistics data. We find that the q^2=0 scale is fitted in excellent agreement with the theoretical long-distance amplitude. Lastly, we find that the observed q^2 shape is explained by the combined effect of the pion and kaon form-factor vector-meson-dominance rho,

A. Ya. Berdnikov, Ya. A. Berdnikov, A. N. Ivanov, V. F. Kosmach

The polarization properties of the charmed Lambda^+_c baryon are investigated in weak non-leptonic four-body Lambda^+_c -> p + K^- + pi^+ + pi^0 decay. The probability of this decay and the angular distribution of the probability are calculated in the effective quark model with chiral U(3)XU(3) symmetry incorporating Heavy Quark Effective theory (HQET) and t

Ashok Goyal, Meenu Dahiya

Two flavor Nambu-Jona-Lasinio model with N components is studied in curved space time at finite temperature and density in the leading 1/N expansion. In four space time dimension the model exhibits first order phase transition for positive curvature. Whereas in flat space an increase in temperature induces a second order phase transition even at finite densi

S. V. Goloskokov

We study spin asymmetries in diffractive $Q \bar Q$ and vector meson production which are sensitive to the spin-dependent part of the two-gluon-nucleon coupling. It is found that the $A_{ll}$ and $A_{lT}$ asymmetry in diffractive reactions can be used to study polarized gluon distributions of the proton.

V. N. Baier, V. M. Katkov

Radiative effects are considered for an electron moving in a medium in the presence of an external electromagnetic field. Anomalous magnetic moment (AMM) of the electron in alpha-order is calculated under these conditions in the form of two-dimensional integral. Behavior of AMM of high energy electron under influence of multiple scattering in a medium is ana

T. Csorgo

I argue that a new form of matter is indeed seen in Pb+Pb collisions at CERN SPS. However, this Quark Matter (QM) is different from the theoretically predicted Quark Gluon Plasma (QGP) because its effective degrees of freedom seem to be the massive (dressed) constituent quarks instead of almost massless quarks and gluons. The equation of state of QM is hard,

Ning Wu, Tu-Nan Ruan, Zhi-Peng Zheng

A new meson mass relation for meson nonet is given after considering mixing with glueball. The mixing between pseudoscalar mesons and pseudoscalar glueball will decrease the mass of glueball by about 500 Mev. So, according to the predicted mass of the pure pseudoscalar glueball given by lattice calculation and effective Hamiltonian, the expected mass of mixe

Vincenzo Barone, Alessandro Drago, Bo-Qiang Ma

We show that the quark fragmentation function $D(z)$ and the quark distribution function $q(x)$ are connected in the $z \to 1$ limit by the approximate relation $D(z)/z \simeq q(2-1/z)$, where both quantities are in their physical regions. Predictions for proton production in inelastic $e^+ e^-$ annihilation, based on the new relation and standard parametriz

Darwin Chang

We give an personal overview of some of the unsolved problems related to hyperon decays. We cover nonleptonic decays, radiative decays and magnetic moments. Some of the theoretical issues are also touched upon.

T. Umeda, R. Katayama, O. Miyamura, H. Matsufuru

We study hadron properties near the deconfining transition in the quenched lattice QCD simulation. This paper focuses on the heavy quarkonium states, such as $J/ψ$ meson. In order to treat heavy quarks at $T>0$, we adopt the $O(a)$ improved Wilson action on anisotropic lattice. We discuss $c\bar{c}$ bound state observing the wave function and compare the mes

The KTeV Collaboration

We report on the first observation of the decay KL -> pi0 ee gamma by the KTeV E799 experiment at Fermilab. Based upon a sample of 48 events with an estimated background of 3.6 +/- 1.1 events, we measure the KL -> pi0 ee gamma branching ratio to be (2.34 +/- 0.35 +/- 0.13)x10^{-8}. Our data agree with recent O(p^6) calculations in chiral perturbation theory

V. Uvarov

DELPHI results are presented on the inclusive production of the neutral mesons rho^0, f_0(980), f_2(1270), K^*0_2(1430) and f'_2(1525) in hadronic Z^0 decays. They are based on about 2 million multihadronic events collected in 1994 and 1995, using the particle identification capabilities of the DELPHI Ring Imaging Cherenkov detectors and measured ionizat

Anthony Vaiciulis

Following the confirmation of the top quark discovery at the Tevatron, the next step is to begin studying its properties. Because the scale of electroweak symmetry breaking is of the same order as the measured top mass, the top quark may be very sensitive to new physics. We describe measurements of the total top-antitop cross section, the top-antitop invaria

A. Borowiec, M. Francaviglia, V. I. Smirichinski

The Euler-Lagrange equations of motion for the most general Ricci type gravitational Lagrangians are derived by means of a purely metric formalism.

A. B. Batista, J. C. Fabris, S. V. B. Goncalves, J. Tossa

Quantization in the mini-superspace of a gravity system coupled to a perfect fluid, leads to a solvable model which implies singularity free solutions through the construction of a superposition of the wavefunctions. We show that such models are equivalent to a classical system where, besides the perfect fluid, a repulsive fluid with an equation of state $p_

James M. Nester, Chiang-Mei Chen, Yu-Heui Wu

Energy-momentum (and angular momentum) for the Metric-Affine Gravity theory is considered from a Hamiltonian perspective (linked with the Noether approach). The important roles of the Hamiltonian boundary term and the many choices involved in its selection-which give rise to many different definitions-are emphasized. For each choice one obtains specific boun

A. Pai, S. V. Dhurandhar, P. Hello, J-Y. Vinet

The large scale interferometric gravitational wave detectors consist of Fabry-Perot cavities operating at very high powers ranging from tens of kW to MW for next generations. The high powers may result in several nonlinear effects which would affect the performance of the detector. In this paper, we investigate the effects of radiation pressure, which tend t

Gary T. Horowitz

A very brief review is given of the current state of research in quantum gravity. Over the past fifteen years, two approaches have emerged as the most promising paths to a quantum theory of gravity: string theory and quantum geometry. I will discuss the main achievements and open problems of each of these approaches, and compare their strengths and weaknesse

Horatiu Cirstea

This thesis is devoted to the study of a calculus that describes the application of conditional rewriting rules and the obtained results at the same level of representation. We introduce the rewriting calculus, also called the rho-calculus, which generalizes the first order term rewriting and lambda-calculus, and makes possible the representation of the non-

David Hochberg, Carmen Molina-Paris, Juan Perez-Mercader, Matt Visser

Classical field theories coupled to stochastic noise provide an extremely powerful tool for modeling phenomena as diverse as turbulence, pattern-formation, and the structural development of the universe itself. In this Letter we sketch a general formalism that maps such systems into a field theory language, and demonstrate how to extract the one-loop physics

Daniel Vernon, Martin Howard

We consider a system of particles undergoing the branching and annihilating reactions A -> (m+1)A and A + A -> 0, with m even. The particles move via long-range Levy flights, where the probability of moving a distance r decays as r^{-d-sigma}. We analyze this system of branching and annihilating Levy flights (BALF) using field theoretic renormalization group

V. F. Correa, G. Nieva, F. de la Cruz

Transverse ac permeability measurements in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ single crystals at low fields and temperatures in a vortex configuration free of external forces show that the decrease of the critical current as measured by magnetization loops at the second peak effect is an artifact due to creep. On the other hand, the increase of critical current a

U. Al Khawaja, H. T. C. Stoof

The recently realized multicomponent Bose-Einstein condensates provide opportunities to explore the rich physics brought about by the spin degrees of freedom. For instance, we can study spin waves and phase separation, macroscopic quantum tunneling, Rabi oscillations, the coupling between spin gradients and superfluid flow, squeezed spin states, vortices and

U. Tartaglino, D. Passerone, E. Tosatti, F. Di Tolla

We present a calculation of the change of free energy of a solid surface upon bending of the solid. It is based on extracting the surface stress through a molecular dynamics simulation of a bent slab by using a generalized stress theorem formula, and subsequent integration of the stress with respect to strain as a function of bending curvature. The method is

V. N. Evteev, M. V. Moiseenko, E. V. Zhuravel, E. Ya. Glushko

It is proposed two models describing transport and absorbtion processes that occur in nanoscale fragments of electrical circuits, pulled adsorbed molecules, atomic or molecular chains connecting electrodes. Discrete chain model of a molecular bridge between metallic electrodes considers quantum jumps between atoms containing the chain. The potential approach

S. Choi, K. Burnett, O. M. Friesch, B. Kneer

We propose an ``interferometric'' scheme for Bose-Einstein condensates using near-field diffraction. The scheme is based on the phenomenon of intermode traces or quantum carpets; we show how it may be used in the detection of weak forces.

Anjan Kundu

The well known string solution to Bethe ansatz equations is shown to be inconsistent in its widely accepted form. A valid refinement demanding higher order corrections in subsequent roots is identified. A new alternative string solution is proposed for finite long chains, consistent with the non-Bethe strings observed earlier.

Jonathan Doye, Florent Calvo

We show that the vibrational entropy can play a crucial role in determining the equilibrium structure of clusters by constructing structural phase diagrams showing how the structure depends upon both size and temperature. These phase diagrams are obtained for example rare gas and metal clusters.

F. Mancini, N. B. Perkins, N. M. Plakida

Spin dynamics is calculated in the ferromagnetic (FM) state of the generalized Kondo lattice model taking into account strong on-site correlations between e_g electrons and antiferromagnetic (AFM) exchange among t_{2g} spins. Our study suggests that competing FM double-exchange and AFM super-exchange interaction lead to a rather nontrivial spin-wave spectrum

Giuliano Benenti, Dima L. Shepelyansky

We study the problem of two particles with Coulomb repulsion in a two-dimensional disordered potential in the presence of a magnetic field. For the regime, when without interaction all states are well localized, it is shown that above a critical excitation energy electron pairs become delocalized by interaction. The transition between the localized and deloc

V. I. Anisimov, I. A. Nekrasov, D. E. Kondakov, T. M. Rice

The electronic structures of the metallic and insulating phases of Ca(2-x)Sr(x)RuO(4) (0<= x <= 2) are calculated using LDA, LDA+U and Dynamical Mean-Field Approximation methods. For x=0 the ground state is an orbitally non-degenerate antiferromagnetic insulator. For 0.2<x<0.5 we propose a state with partial orbital and spin ordering. For x>0.5 the observed

Yong Baek Kim, Chetan Nayak, Eugene Demler, N. Read

We consider a number of strongly-correlated quantum Hall states which are likely to be realized in bilayer quantum Hall systems at total Landau level filling fraction ${ν_T}=1$. One state, the $(3,3,-1)$ state, can occur as an instability of a compressible state in the large $d/l_B$ limit, where $d$ and $l_B$ are the interlayer distance and magnetic length,

Xuelei Chen

There is a tension between observed Helium abundance and the prediction of the standard Big Bang Nucleosynthesis. We show that non-minimally quintessence model may help to reduce this tension between theory and observation.

Xuelei Chen

We discuss BBN in the presence of a non-minimally coupled quintessence model. In some of these models, the gravitational constant and cosmic expansion rate are smaller than standard model predicts. The Helium abundance is then smaller, possibly resolve the marginal disagreement between theory and observation. Furthermore, the constraint on neutrino species m

N. Murray, B. Chaboyer, B. Hansen, P. Arras

We study spectroscopically determined iron abundances of 642 solar-type stars to search for the signature of accreted iron-rich material. We find that the metallicity [Fe/H] of a subset of 466 main sequence stars, when plotted as a function of stellar mass, mimics the pattern seen in lithium abundances in open clusters. Using Monte Carlo models we find that,

Zoltan Haiman, Abraham Loeb

The recent discoveries of luminous quasars at high redshifts imply that black holes more massive than a few billion solar masses have been assembled already when the universe was less than a billion years old. We show that the existence of these black holes is not surprising in popular hierarchical models of structure formation. For example, the black hole n

Yurij Baryshev, Arthur Chernin, Pekka Teerikorpi

Our local environment at $r<10$ Mpc expands linearly and smoothly, as if ruled by a uniform matter distribution, while observations show the very clumpy local universe. This is a long standing enigma in cosmology. We argue that the recently discovered vacuum or quintessence (dark energy (DE) component with the equation of state $p_Q = w ρ_Q c^2$, $w \in [-1,

Ignacio Ferrin, D. Rabinowitz, B. Schaefer, J. Snyder

We describe the discovery circumstances and photometric properties of 2000 EB173, now one of the brightest trans-Neptunian objects (TNOs) with opposition magnitude m_R=18.9 and also one of the largest Plutinos, found with the drift-scanning camera of the QUEST Collaboration, attached to the 1-m Schmidt telescope of the National Observatory of Venezuela. We m

S. H. Hansen

We review current astrophysical bounds on MeV sterile neutrinos, and then we discuss why a sterile keV neutrino is a natural warm dark matter candidate.

Thomas K. Gaisser

Several of the models for origin of the highest energy cosmic rays also predict significant neutrino fluxes. A common factor of the models is that they must provide sufficient power to supply the observed energy in the extragalactic component of the cosmic radiation. The assumption that a comparable amount of energy goes into high-energy neutrinos allows a m

Thomas K. Gaisser

I give a brief overview of cosmic ray physics, highlighting some key questions and how they will be addressed by new experiments.

Alice K. Harding, Bing Zhang

We investigate whether gamma-ray pulsars viewed at a large angle to the neutron star magnetic pole could contribute to the new population of galactic unidentified EGRET sources associated with the Gould Belt. The faint, soft nature of these sources is distinctly different from both the properties of unidentified EGRET sources along the galactic plane and of

P. Barmby, J. P. Huchra, J. P. Brodie

We combine our compilation of photometry of M31 globular cluster and probable cluster candidates with new near-infrared photometry for 30 objects. Using these data we determine the globular cluster luminosity function (GCLF) in multiple filters for the M31 halo clusters. We find a GCLF peak and dispersion of V_0^0=16.84 +/-0.11, sigma_t=0.93 +/- 0.13 (Gaussi

E. Kotok, P. Naselsky, D. Novikov, I. Novikov

We discuss some new problems of the modern cosmology which arose after the BOOMERANG and MAXIMA-1 successful missions. Statistics of high peaks of the CMB anisotropy is analyzed and we discuss possible inner structure of such peaks in the observational data of future MAP and PLANCK missions. We have investigated geometrical and statistical properties of the

J. Lim, S. Leon, F. Combes, Dinh-V-Trung

We report the detection of $^{12}$CO~($1 \to 0$) and $^{12}$CO~($2 \to 1$) emission from the central regions ($\lesssim 5$--$10 {\rm kpc}$) of the two powerful radio galaxies 3C~31 and 3C~264. Their individual CO emission exhibits a double-horned line profile that is characteristic of an inclined rotating disk with a central depression at the rising part of

S. Bhattacharyya, R. Misra, A. V. Thampan

General relativistic spectra from accretion disks around rotating neutron stars in the appropriate space-time geometry for several different equation of state, spin rates and mass of the compact object have been computed. The analysis involves the computation of the relativistically corrected radial temperature profiles and the effect of Doppler and gravitat

K. Iwasawa, A. C. Fabian, S. Ettori

We present X-ray imaging spectroscopy of the extremely luminous infrared galaxy IRAS 09104+4109 (z=0.442) obtained with the Chandra X-ray Observatory. With the arcsec resolution of Chandra, an unresolved source at the nucleus is separated from the surrounding cluster emission. A strong iron K line at 6.4 keV on a very hard continuum is detected from the nucl

W. Kluzniak T. Bulik D. Gondek-Rosinska

It has been suggested that both X-ray bursters and millisecond radio pulsars may be strange (quark) stars, rather than neutron stars. Confirming (or rejecting) this suggestion may require knowing what role strong-field effects of general relativity play in the accretion flow of the compact X-ray source in low-mass X-ray binaries (LMXBs). We discuss the range

P. Harmanec, P. Habuda, S. Stefl, P. Hadrava

An analysis of accurate radial velocities (RVs) of the Be star gamma Cas from 295 Reticon spectrograms secured between October 1993 and May 2000 allowed us to prewhiten the RVs for the long-term changes and to obtain the first orbital RV curve of this star. The orbital period is 203d59 and the orbit has an eccentricity of 0.26. The orbital motion is detectab

John F. C. Wardle, Daniel C. Homan

We review recent observations of circularly polarized radiation from AGN made with the VLBA and with the ATCA. We also discuss briefly the detections of the Galactic sources Sag A* and SS433. The origin of the circular polarization is still an open question in most cases, and we discuss four possible mechanisms. Detectable circular polarization is a common p

Sverre J. Aarseth, Rosemary A. Mardling

Multiple systems play an important role in the evolution of star clusters. First we discuss several formation mechanisms which depend on the presence of binaries, either primordial or of dynamical origin. Hierarchical configurations are often stable over long times and yet may experience evolution of the internal orbital parameters. We describe an attempt to

S. A. Levshakov, W. H. Kegel, I. I. Agafonova

We show that the difference between the Ar and Si relative abundance ratio derived from FUSE absorption spectra and from the HII regions of I Zw 18 is a consequence of the microturbulent analysis applied to the absorption spectra. FUSE observations were performed with a large entrance aperture which fully covered the galaxy. This means that the observed prof

J. Martin-Pintado, J. R. Rizzo, P. de Vicente, N. J. Rodriguez-Fernandez

We present observations of C2H5OH toward molecular clouds in Sgr A, Sgr B2 and associated with thermal and non-thermal features in the Galactic center. C2H5OH emission in Sgr A and Sgr B2 is widespread, but not uniform. C2H5OH emission is much weaker or it is not detected in some molecular clouds in both complexes, in particular those with radial velocities

Andreas Burkert, Joseph Silk

The observed relation between central black hole mass and spheroid velocity dispersion is interpreted in terms of a self-regulation model that incorporates a viscous Keplerian accretion disk to feed the black hole, embedded in a massive, self-gravitating star forming disk that eventually populates the spheroid. The model leads to a constant ratio between bla

A. Aloisi, M. Clampin, E. Diolaiti, L. Greggio

We present HST NICMOS photometry of the resolved stellar population in NGC 1569. The CMD in the F110W and F160W photometric bands contains ~2400 stars with a formal photometric error < 0.1 mag down to J~23.5 and H~22.5. We describe the data processing which is required to calibrate the instrumental peculiarities of NICMOS. Two different packages for PSF-fitt

A. Heger, S. E. Woosley, G. Martinez-Pinedo, K. Langanke

Recent shell-model calculations of weak-interaction rates for nuclei in the mass range A = 45 - 65 have resulted in substantial revisions to the hitherto standard set of Fuller, Fowler, & Newman (FFN). In particular, key electron-capture rates, such as that for Co60 are much smaller. We consider here the effects of these revised rates on the presupernova (po

The Macho collaboration, C. Alcock, R. A. Allsman, D. R. Alves

We report on a search for long duration microlensing events towards the Large Magellanic Cloud. We find none, and therefore put limits on the contribution of high mass objects to the Galactic dark matter. At 95% confidence level we exclude objects in the mass range 0.3 solar masses to 30.0 solar masses from contributing more than 4 times 10^11 solar masses t