May 2002 arXiv papers — page 16

A. Ya. Kazakov

The sending station being the classical device can be eavesdropped by classical means. Dense coding and quantum nature of wave function give the additional resource to raise the safety of the quantum channel as a whole.

Wolfgang Dür, Christoph Simon, J. Ignacio Cirac

Several experiments and experimental proposals for the production of macroscopic superpositions naturally lead to states of the general form $|ϕ_1>^{\otimes N}+|ϕ_2>^{\otimes N}$, where the number of subsystems $N$ is very large, but the states of the individual subsystems have large overlap, $|łϕ_1|ϕ_2 \r|^2=1-ε^2$. We propose two different methods for assi

W. P. Bowen, R. Schnabel, N. Treps, H. A. Bachor

We propose and demonstrate a system that produces squeezed vacuum using a pair of optical parametric amplifiers. This scheme allows the production of phase sidebands on the squeezed vacuum which facilitate phase locking in downstream applications. We observe strong, stably locked, continuous wave vacuum squeezing at frequencies as low as 220 kHz. We propose

Wang Xiang-bin

We propose a simple scheme to produce the polarization entangled photon pairs without the type II phase match. The same scheme can also be used to produce the macroscopic entangled photon states in both photon number space and the polarization space(A. Lamas-Linares, J.C. Howell and D. Bouwmeester, Nature, 412887(2001)). Advantages and applications of our sc

Giacomo Sguazzoni

The ALEPH Silicon Vertex Detector for LEP2 featured a laser survey system to monitor its mechanical stability. The analysis of laser system data from 1997 to 2000 showed that VDET suffered a time-dependent displacement. It resulted to be compatible with a deformation of the support structure that made the device to slowly rotate during the data-taking. A max

K. H. Mariwalla, N. D. Hari Dass

Sir Joseph LARMOR showed in 1897 that an oscillating electric charge emits radiation energy proportional to (acceleration)$^2$. At first sight,the result appears to be valid for arbitrary accelerations. But, perpetual uniform acceleration has been a case of nagging doubts, as radiation reaction vanishes and the equivalence principle, as also conformal symmet

M. R. Mahdavi

In this note we wish to demonstrate that the concept of efficiency loophole, as far as a local realistic model is concerned, is a self-defeating one since it implies that the static fields (for example, electric or gravitational) of and elementary particle must be in the form of quantized superluminal pulses. The Idea, however, may still be advocated by the

V. Greco, M. Colonna, M. Di Toro, F. Matera

We discuss a fully relativistic Landau Fermi liquid theory based on the Quantum Hadro-Dynamics ($QHD$) effective field picture of Nuclear Matter ({\it NM}). From the linearized kinetic equations we get the dispersion relations of the propagating collective modes. We focus our attention on the dynamical effects of the interplay between scalar and vector chann

A. M. Mukhamedzhanov, F. M. Nunes

The low-energy behavior of the astrophysical S-factor for E1 direct radiative captures a(p,gamma)b leading to loosely bound final states (b=a+p) is investigated. We derive a first-order integral representation for S(E) and focus on the properties around zero energy. We show that it is the competition between various effects, namely the remnant Coulomb barrie

W. M. Alberico, A. Lavagno, P. Quarati

We show that non-conventional statistical effects (due to the presence of long range forces, memory effects, correlations and fluctuations) can be very relevant in the interpretation of the experimental observables in relativistic heavy-ions collisions. Transverse mass spectrum, transverse momentum fluctuations and rapidity spectra are analysed in the framew

Jong-Won Kim, Edward Ott

We study the statistics and characteristics of rare intense events in two types of two dimensional Complex Ginzburg-Landau (CGL) equation based models. Our numerical simulations show finite amplitude collapse-like solutions which approach the infinite amplitude solutions of the nonlinear Schrödinger (NLS) equation in an appropriate parameter regime. We also

Ricardo Lopez-Ruiz, G. B. Mindlin, C. Perez-Garcia, J. R. Tredicce

We show the possibility of achieving experimentally a Takens-Bogdanov bifurcation for the nonlinear interaction of two transverse modes ($l = \pm 1$) in a $CO_2$ laser. The system has a basic O(2) symmetry which is perturbed by some symmetry-breaking effects that still preserve the $Z_2$ symmetry. The pattern dynamics near this codimension two bifurcation un

Stephen Doty, Anne Henke

We use tilting modules to study the structure of the tensor product of two simple modules for the algebraic group $\SL_2$, in positive characteristic, obtaining a twisted tensor product theorem for its indecomposable direct summands. Various other related results are obtained, and numerous examples are computed.

Valerio Toledano-Laredo

We review the Kohno-Drinfeld theorem as well as a conjectural analogue relating quantum Weyl groups to the monodromy of a flat connection D on the Cartan subalgebra of a complex, semi-simple Lie algebra g with poles on the root hyperplanes and values in any g-module V. We sketch our proof of this conjecture when g=sl(n) and when g is arbitrary and V is a vec

A. P. Veselov, J. P. Ward

The behaviour of real zeroes of the Hurwitz zeta function $$ζ(s,a)=\sum_{r=0}^{\infty}(a+r)^{-s}\qquad\qquad a > 0$$ is investigated. It is shown that $ζ(s,a)$ has no real zeroes $(s=σ,a)$ in the region $a >\frac{-σ}{2πe}+\frac{1}{4πe}\log (-σ) +1$ for large negative $σ$. In the region $0 < a < \frac{-σ}{2πe}$ the zeroes are asymptotically located at the lin

S. Kitaev, T. Mansour

In [BabStein] Babson and Steingr\&#39;ımsson introduced generalized permutation patterns that allow the requirement that two adjacent letters in a pattern must be adjacent in the permutation. In [Kit1] Kitaev considered simultaneous avoidance (multi-avoidance) of two or more 3-patterns with no internal dashes, that is, where the patterns correspond to contig

Myunghyun Oh, Kevin Zumbrun

We establish instability of periodic traveling waves arising in conservation laws featuring phase transition. The analysis uses the Evans function framework introduced by R.A. Gardner in the periodic case. The main new tool is a periodic generalization of the stability index introduced by Gardner and Zumbrun in the traveling front or pulse case.

Masanobu Kaneko, Hiroyuki Ochiai

We give a formula for the coefficients of the Yablonskii-Vorob&#39;ev polynomial. Also the reduction modulo a prime number of the polynomial is studied.

Claudio Meneghini

We extend Painlevé&#39;s determinateness theorem from the theory of ordinary differential equations in the complex domain allowing more general &#39;multiple-valued&#39; Cauchy&#39;s problems. We study $C^0-$continuability (near singularities) of solutions.

Frank Sottile, Thorsten Theobald

We show that there are 3 \cdot 2^(n-1) complex common tangent lines to 2n-2 general spheres in R^n and that there is a choice of spheres with all common tangents real.

Wayne R. Lundberg

A geometric relationship between loop quantum gravity and partitioned (triangulated) string theory is discussed. Combinatorial analysis reveals that three spatial and three curvature dimensions, intrinsic to the partitioned string, are necessary to replicate Standard Model particles and interactions. This analysis has established that particulate mass is det

Rajesh Gopakumar

We argue that string interactions in a PP-wave spacetime are governed by an effective coupling $g_{eff}=g_s(μp^+\apm)f(μp^+ \apm)$ where $f(μp^+ \apm)$ is proportional to the light cone energy of the string states involved in the interaction. This simply follows from generalities of a Matrix String description of this background. $g_{eff}$ nicely interpolate

V. Popkov, M. E. Fouladvand, G. M. Schuetz

We propose a dynamical matrix product ansatz describing the stochastic dynamics of two species of particles with excluded-volume interaction and the quantum mechanics of the associated quantum spin chains respectively. Analyzing consistency of the time-dependent algebra which is obtained from the action of the corresponding Markov generator, we obtain suffic

Martin Cederwall, Bengt E. W. Nilsson, Dimitrios Tsimpis

We compute the spinorial cohomology of ten-dimensional abelian SYM at order alpha&#39;^3 and we find that it is trivial. Consequently, linear supersymmetry alone excludes the presence of alpha&#39;^3-order corrections. Our result lends support to the conjecture that there may be a unique supersymmetric deformation of ordinary ten-dimensional abelian SYM.

Sudipta Mukherji, Shesansu Sekhar Pal

We calculate the correction to the Bekenstein-Hawking entropy formula for five dimensional AdS-Schwarzschild black holes due to thermodynamic fluctuations. The result is then compared with the boundary gauge theory entropy corrections via AdS/CFT correspondence. We then further generalise our analysis for the rotating black hole in five dimensional AdS space

C. Bachas

I analyze the asymptotic symmetries of a theory of gravity in a background consisting of two patches of ${\rm AdS}_3$ spacetime glued together along an ${\rm AdS}_2$ brane. These are generated by a single Virasoro algebra, as expected from the conjectured dual description in terms of a scale-invariant interface separating two conformal field theories. Contri

Bernd-Dietrich Doerfel

We propose a Lie-algebra model for noncommutative coordinate and momentum space . Based on a rigid commutation relation for the commutators of space time operators the model is quite constrained if one tries to keep Lorentz invariance as much as possible. We discuss the question of invariants esp. the definition of a mass.

U. Lindström

This set of lectures contain a brief review of some basic supersymmetry and its representations, with emphasis on superspace and superfields. Starting from the Poincaré group, the supersymmetric extensions allowed by the Coleman-Mandula theorem and its generalisation to superalgebras, the Haag, Lopuszanski and Sohnius theorem, are discussed. Minkowski space

Ulf Lindstrom

On a historical note, we first describe the early superspace construction of counterterms in supergravity and then move on to a brief discussion of selected areas in string theory where higher order supergravity invariants enter the effective theories. Motivated by this description we argue that it is important to understand $p$-brane actions with $\k$-invar

Carlo Oleari

We discuss the status of the next-to-next-to-leading order calculation in scattering processes, describing briefly the challenges that have been overcome and what challenges are still to be resolved.

M. Bleicher, F. M. Liu, J. Aichelin, H. J. Drescher

A novel mechanism of H^0 and strangelet production in hadronic interactions within the Gribov-Regge approach is presented. In contrast to traditional distillation approaches, here the production of multiple (strange) quark bags does not require large baryon densities or a QGP. The production cross section increases with center of mass energy. Rapidity and tr

Christine Davies

A general introduction to lattice QCD suitable for graduate students in experimental and theoretical particle physics. Aimed at those who want to know how lattice calculations are done, and what the pitfalls are, without having to do the calculations themselves.

S. Groot Nibbelink

In this talk we review calculations of FI-tadpoles in 5 dimensional (non-)supersymmetric orbifold theories. Some consequences of these tadpoles are discussed: quadratic Higgs-mass sensitivity to a high scale, and localization of bulk matter fields to the orbifold fixed points.

Jan Kalinowski

It is shown how the fundamental gaugino and higgsino parameters of the chargino and neutralino system in the MSSM can completely be determined in high--precision experiments at e+e- linear colliders even if in their initial phase only the light charginos $\tildeχ^\pm_1$ and the light neutralinos $\tildeχ^0_1$ and $\tildeχ^0_2$ are kinematically accessible.

Victor Novozhilov, Yuri Novozhilov

We consider extended chiral group $Eχ$ of gauge plus chiral transformations of the quark path integral in the background gauge and present novel type of color solitons described by the effective action resulting from bosonization. O(3) solitons are formed by a chiral field including parameters with diquark quantum numbers within symplectic subgroup of $Eχ$,

John B. Kogut, Dominique Toublan, D. K. Sinclair

SU(2) lattice gauge theory with four flavors of quarks is simulated at nonzero chemical potential $μ$ and temperature $T$ and the results are compared to the predictions of Effective Lagrangians. Simulations on $16^4$ lattices indicate that at zero $T$ the theory experiences a second order phase transition to a diquark condensate state. Several methods of an

R. D. Young, D. B. Leinweber, A. W. Thomas, S. V. Wright

We extend to quenched QCD an earlier investigation of the chiral structure of the masses of the nucleon and the delta in lattice simulations of full QCD. Even after including the meson-loop self-energies which give rise to the leading and next-to-leading non-analytic behaviour (and hence the most rapid variation in the region of light quark mass), we find su

CDF Collaboration

The exclusive gamma-met signal has a small standard model cross-section and is thus a good channel in which to look for signs of new physics. This signature is predicted by models with a superlight gravitino or with large extra spatial dimensions. We search for such signals at the CDF detector at the Tevatron, using 87 pb^-1 of data at sqrt(s) = 1.8 TeV, and

Dieter Best

We report recent results in the search for the rare B meson decays B-->rho gamma and B0-->pi0 pi0. These results are based on 56.4 1/fb collected by the BaBar Collaboration at the SLAC PEP-II e+e- B Factory. We set new 90% confidence level upper limits BR(B0 --> rho0 gamma) < 1.5 x 10^-6, BR(B+ --> rho+ gamma) < 2.8 x 10^-6, and BR(B0 --> pi0 pi0) < 3.4 x 10

ALEPH Collaboration

A search for the Higgsstrahlung process ${\rm e}^+{\rm e}^- \to {\rm HZ}$ is carried out, covering decays of the Higgs boson into any quark pair, a gluon pair or a tau pair. The analysis is based on the $630 {\rm pb}^{-1}$ of data collected by the ALEPH detector at LEP at centre-of-mass energies from 189 to 209 GeV. A 95% C.L. lower mass limit of 109.1\mc2 i

S. Mohrdieck

An overview of recent results from the H1 and ZEUS collaborations on vector meson production in electron-proton collisions at HERA is given. For diffractive vector meson production the energy dependence is discussed. The dependences on different scales, M_VM, Q^2 and |t|, are investigated. The data are compared to pQCD theoretical calculations. In addition n

T. Alderweireld

The data collected by the DELPHI experiment up to the highest LEP2 energies were used to put constraints on the Anomaly Mediated SUSY Breaking model with a flavour independent m0 parameter. The experimental searches covered several possible signatures experimentally accessible at LEP, with either the lightest neutralino, the sneutrino or the stau being the L

Andrea Longhin

A selection of topics on open heavy quark production at HERA are reviewed here. Measurements of charm fragmentation parameters will be presented together with developments in the study of D* di-jet angular distributions. Charm production in deep inelastic scattering (DIS) is also discussed. Finally we deal with recent measurements of b cross sections using i

Akimasa Ishikawa

We report on the results of penguin-mediated B decays at the Belle experiment. The analyses were based on approximately 32 million $B\bar{B}$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+e^-$ storage ring. The $b \to s γ$ transition was studied through exclusive decays: $B \to K^{*} γ$, $B^0 \to K_{2}^{*}(1430)^0 γ$, $B^+

M. Verzocchi

Run 2 of the Tevatron collider at Fermilab has begun in the spring of 2001. During its first year of operation the Tevatron has delivered a luminosity of approximately 30/pb to the Dzero experiment. These data have been used to commission the detector. The progress in understanding the detector performance and the prospects for an exciting physics program to

Mark D. Roberts

In many circumstances the perfect fluid conservation equations can be directly integrated to give a Geometric-Thermodynamic equation: typically that the lapse $N$ is the reciprocal of the enthalphy $h$, ($ N=1/h$). This result is aesthetically appealing as it depends only on the fluid conservation equations and does not depend on specific field equations suc

Gioel Calabrese, Jorge Pullin, Olivier Sarbach, Manuel Tiglio

We study the stability properties of the Kidder-Scheel-Teukolsky (KST) many-parameter formulation of Einstein&#39;s equations for weak gravitational waves on flat space-time from a continuum and numerical point of view. At the continuum, performing a linearized analysis of the equations around flat spacetime, it turns out that they have, essentially, no non-

D. V. Ahluwalia, N. Dadhich, M. Kirchbach

We unearth spacetime structure of massive vector bosons, gravitinos, and gravitons. While the curvatures associated with these particles carry a definite spin, the underlying potentials cannot be, and should not be, interpreted as single spin objects. For instance, we predict that a spin measurement in the rest frame of a massive gravitino will yield the res

H. -Th. Elze, O. Schipper

We study a classical reparametrization-invariant system, in which ``time&#39;&#39; is not a priori defined. It consists of a nonrelativistic particle moving in five dimensions, two of which are compactified to form a torus. There, assuming a suitable potential, the internal motion is ergodic or more strongly irregular. We consider quasi-local observables whi

Zolt&#39;an Perj&#39;es

A pair of simple wave equations is presented for the symmetric gravitational and electromagnetic perturbations of a charged black hole. One of the equations is uncoupled, and the other has a source term given by the solution of the first equation. The derivation is presented in full detail for either axially symmetric or stationary perturbations, and is quit

T. P. Shestakova

Several years ago the so-called quantum geometrodynamics in extended phase space was proposed. The main role in this version of quantum geometrodynamics is given to a wave function that carries information about geometry of the Universe as well as about a reference frame in which this geometry is studied. We consider the evolution of a physical object (the U

Carlos Barcelo, Matt Visser

The tension, if not outright inconsistency, between quantum physics and general relativity is one of the great problems facing physics at the turn of the millennium. Most often, the problems arising in merging Einstein gravity and quantum physics are viewed as Planck scale issues (10^{19} GeV, 10^{-34} m, 10^{-45} s), and so safely beyond the reach of experi

Amir H. Abbassi, Amir M. Abbassi

According to a simple model of inertia a Machianized theory of special and general relativity named as relational relativity is presented.

Menno M. van Zaanen

This thesis introduces a new unsupervised learning framework, called Alignment-Based Learning, which is based on the alignment of sentences and Harris&#39;s (1951) notion of substitutability. Instances of the framework can be applied to an untagged, unstructured corpus of natural language sentences, resulting in a labelled, bracketed version of that corpus.

Fei Zhou, Boris Spivak

The boundary condition in Eq.6 is invalid.

Leon Balents, Pierre Le Doussal

We study thermally activated dynamics using functional renormalization within the field theory of randomly pinned elastic systems, a prototype for glasses. It appears through an essentially non-perturbative boundary layer in the running effective action, for which we find a consistent scaling ansatz to all orders. We find that in the statics the boundary lay

Henk van Beijeren

The short time behavior of nucleation probabilities is studied by representing nucleation as diffusion in a potential well with escape over a barrier. If initially all growing nuclei start at the bottom of the well, the first nucleation time on average is larger than the inverse nucleation frequency. Explicit expressions are obtained for the short time proba

B. Derrida, J. L. Lebowitz, E. R. Speer

We consider the asymmetric exclusion process (ASEP) in one dimension on sites $i = 1,..., N$, in contact at sites $i=1$ and $i=N$ with infinite particle reservoirs at densities $ρ_a$ and $ρ_b$. As $ρ_a$ and $ρ_b$ are varied, the typical macroscopic steady state density profile $\bar ρ(x)$, $x\in[a,b]$, obtained in the limit $N=L(b-a)\to\infty$, exhibits shoc

R. I. Dzhioev, V. L. Korenev, I. A. Merkulov, B. P. Zakharchenya

We report on the optical manipulation of the electron spin relaxation time in a GaAs based heterostructure. Experimental and theoretical study shows that the average electron spin relaxes through hyperfine interaction with the lattice nuclei, and that the rate can be controlled by the electron-electron interactions. This time has been changed from 300 ns dow

E. V. Tsiper, Z. G. Soos, W. Gao, A. Kahn

The electronic polarization energies, P = (P+) + (P-), of a PTCDA (perylenetetracarboxylic acid dianhydride) cation and anion in a crystalline thin film on a metallic substrate are computed and compared with measurements of the PTCDA transport gap on gold and silver. Both experiments and theory show that P is 500 meV larger in a PTCDA monolayer than in 50 A

Weixing Lu, Charles M. Knobler, Robijn F. Bruinsma, Michael Dennin

The maximum pressure a two-dimensional surfactant monolayer is able to withstand is limited by the collapse instability towards formation of three-dimensional material. We propose a new description for reversible collapse based on a mathematical analogy between the formation of folds in surfactant monolayers and the formation of Griffith Cracks in solid plat

John Lauridsen, Michael Twardos, Michael Dennin

We report on experimental measurements of the flow behavior of a wet, two-dimensional foam under conditions of slow, steady shear. The initial response of the foam is elastic. Above the yield strain, the foam begins to flow. The flow consists of irregular intervals of elastic stretch followed by sudden reductions of the stress, i.e. stress drops. We report o

Manuel Valin-Rodriguez, Antonio Puente, Llorens Serra, Vidar Gudmundsson

The dipole modes of non-parabolic quantum dots are studied by means of their current and density patterns as well as with their local absorption distribution. The anticrossing of the so-called Bernstein modes originates from the coupling with electron-hole excitations of the two Landau bands which are occupied at the corresponding magnetic fields. Non-quadra

L. S. Levitov, A. M. Tsvelik

Electron interactions reinforce minigaps induced in metallic nanotubes by an external field and turn the gap field dependence into a universal power law. An exactly solvable Gross-Neveau model with an SU(4) symmetry is derived for neutral excitations near half-filling. Charge excitations, described by a sin-Gordon perturbation of Luttinger liquid theory, are

A. V Boris, D. Munzar, N. N. Kovaleva, B. Liang

The far-infrared (FIR) c axis conductivity of a Bi2223 crystal has been measured by ellipsometry. Below T$_c$ a strong absorption band develops near 500 cm $^{-1}$, corresponding to a transverse Josephson-plasmon. The related increase in FIR spectral weight leads to a giant violation of the Ferrell-Glover-Tinkham sum-rule. The gain in c axis kinetic energy a

Jaroslav Fabian, Igor Zutic, S. Das Sarma

The interplay between spin and charge transport in electrically and magnetically inhomogeneous semiconductor systems is investigated theoretically. In particular, the theory of spin-polarized bipolar transport in magnetic p-n junctions is formulated, generalizing the classic Shockley model. The theory assumes that in the depletion layer the nonequilibrium ch

F. H. Zong, C. Lin, D. M. Ceperley

To determine the state of spin polarization of the 3D electron gas at very low densities and zero temperature, we calculate the energy versus spin polarization using Diffusion Quantum Monte Carlo methods with backflow wavefunctions and twist averaged boundary conditions. We find a second order phase transition to a partially polarized phase at r_s = 50 \pm 2

D. V. Livanov, A. A. Varlamov

We report the calculation of paraconductivity in carbon nanotubes above the superconducting transition temperature. The complex behavior of paraconductivity depending upon the tube radius, temperature and magnetic field strength is analyzed. The results are qualitatively compared with recent experimental observations in carbon nanotubes of an inherent transi

Baigeng Wang, Jian Wang

It is well known that the particles in a beam of Boson obeying Bose-Einstein statistics tend to cluster (bunching effect), while the particles in a degenerate beam of Fermion obeying Fermi-Dirac statistics expel each other (anti-bunching effect). Here we investigate, for the first time, the statistical correlation effect for the composite Boson, which is for

Satya N. Majumdar, David S. Dean

Motivated by a computer science algorithm known as `linear probing with hashing&#39; we study a new type of percolation model whose basic features include a sequential `dropping&#39; of particles on a substrate followed by their transport via a `pushing&#39; mechanism. Our exact solution in one dimension shows that, unlike the ordinary random percolation mod

Peiqing Tong, Baowen Li, Bambi Hu

The energy spectra and quantum diffusion of an electron in a 1D incommensurate Frenkel-Kontorova (FK) model are studied numerically. We found that the spectral and dynamical properties of electron display quite different behaviors in invariance circle regime and in Cantorus regime. In the former case, it is similar to that of the Harper model, whereas in the

Hyun C. Lee

The optical conductivities of two one-dimensional narrow-gap semiconductors, anticrossing quantum Hall edge states and carbon nanotubes, are studied using bosonization method. A lowest order renormalization group analysis indicates that the bare band gap can be treated perturbatively at high frequency/temperature. At very low energy scale the optical conduct

Sune Norhoj Jespersen

We use molecular dynamics simulations to study a model of the gelation transition with a dynamic bond forming procedure. After establishing evidence for 3D percolation as the static universality class, we turn our attention to the dynamics of clusters at the gelation point, focusing in particular on the behavior of the diffusion constant D(s) as a function o

Baowen Li, Lei Wang, Bambi Hu

Heat conduction in three types of 1D channels are studied. The channels consist of two parallel walls, right triangles as scattering obstacles, and noninteracting particles. The triangles are placed along the walls in three different ways: (a) periodic, (b) disordered in height, and (c) disordered in position. The Lyapunov exponents in all three models are z

V. Yu. Irkhin

First-order field-induced spin reorientation transitions in multisublattice intermetallic compounds are considered within an anisotropic Heisenberg model. Unlike previous works, only leading-order anisotropy constants of the sublattices are included. The exchange interactions both between the rare-earth (RE) and transition metal (TM) sublattices and within t

Joel M. Weisberg, Joseph H. Taylor

We have carefully measured the pulse profile of the binary pulsar PSR B1913+16 at 21 cm wavelength for twenty years, in order to search for variations that result from general relativistic geodetic precession of the spin axis. The profile width is found to decrease with time in its inner regions, while staying essentially constant on its outer skirts. We fit

Richard D. Robinson, Myron A. Smith, Gregory W. Henry

gamma Cas (B0.5e) is known to be a unique X-ray source because ot its moderate L_x, hard X-ray spectrum, and light curve punctuated by ubiquitous flares and slow undulations. Its X-ray peculiarities have led to a controversy concerning their origin: either from wind infall onto a putative degenerate companion, as for typical Be/X-ray binaries, or from the Be

Patrick J. Lowrance, J. Davy Kirkpatrick, Charles A. Beichman

Upsilon Andromedae is an F8V star known to have an extrasolar system of at least 3 planets in orbit around it. Here we report the discovery of a low-mass stellar companion to this system. The companion shares common proper motion, lies at a projected separation of ~750 AU, and has a spectral type of M4.5V. The effect of this star on the radial velocity of th

E. I. Chiang

Beneath the fusion-encrusted surfaces of the most primitive stony meteorites lies not homogeneous rock, but a profusion of millimeter-sized igneous spheres. These chondrules, and their centimeter-sized counterparts, the calcium-aluminum-rich inclusions, comprise more than half of the volume fraction of chondritic meteorites. They are the oldest creations of

E. I. Chiang, N. Murray

The orbits of the outer two known planets orbiting Upsilon Andromedae are remarkably eccentric. Planet C possesses an orbital eccentricity of e1 = 0.253. For the more distant planet D, e2 = 0.308. Previous dynamical analyses strongly suggest that the two orbits are nearly co-planar and are trapped in an apsidal resonance in which the difference between their

Abraham Loeb, Eli Waxman

We show that if the sources of ultra-high energy cosmic rays (UHECRs) with energies E>10^{19}eV are associated with galaxies, then the production of UHECRs must occur in transient events. Our galaxy is currently at a dim state in between transients. The time interval between transients is >3x10^4 years if the minimum Lorentz factor to which protons are accel

I. Rogachevskii, N. Kleeorin

It is demonstrated that the two-point correlation function of the magnetic helicity in the case of zero mean magnetic field has anomalous scalings for both, compressible and incompressible turbulent helical fluid flow. The magnetic helicity in the limit of very high electrical conductivity is conserved. This implies that the two-point correlation function of

Vladimir Yurchenko, John Anthony Murphy, Jean-Michel Lamarre

We study the electromagnetic coupling of the array of Gaussian and multi-moded horn antennas to the dual-reflector submillimeter-wave telescope on the ESA PLANCK Surveyor designed for measuring the temperature anisotropies and polarization characteristics of the cosmic microwave background. In this paper, we present the results of our analysis concerning the

Bacham E. Reddy, David L. Lambert, Chris Laws, Guillermo Gonzalez

Using very high-resolution (R$\sim$ 125,000) and high quality (S/N $\geq$ 350) spectra, we have searched for $^{6}$Li in stars hosting extra-solar planets. From detailed profile-fitting of the Li {\sc i} resonance line at 6707.7 Å, we find no significant amount of $^{6}$Li relative to the $^{7}$Li for any of 8 planet bearing stars ($^{6}$Li/$^{7}$Li $\leq$ 0

Michael Doran, Christof Wetterich

Quintessence -- the energy density of a slowly evolving scalar field -- may constitute a dynamical form of the homogeneous dark energy in the universe. We review the basic idea in the light of the cosmological constant problem. Cosmological observations or a time variation of fundamental `constants&#39; can distinguish quintessence from a cosmological consta

N. Kleeorin, D. Moss, I. Rogachevskii, D. Sokoloff

We demonstrate that the inclusion of the helicity flux in the magnetic helicity balance in the nonlinear stage of galactic dynamo action results in a radical change in the magnetic field dynamics. The equilibrium value of the large-scale magnetic field is then approximately the equipartition level. This is in contrast to the situation without the flux of hel

Poonam Chandra, Alak Ray, Sanjay Bhatnagar

Multi-frequency observations of two radio bright SNe (SN1993J, SN1979C) carried out over a year with GMRT are presented. Their radio light curves trace the evolution of the mass loss in the stellar wind before the pre-supernova star exploded. Their spectra at low frequencies distinguish between the synchrotron self-absorption and free-free absorption based m

A. Tarchi, C. Henkel, A. B. Peck, K. M. Menten

We report the detection of 22 GHz water vapor emission toward the starburst galaxy NGC2146, made using the Effelsberg 100-m telescope. Interferometric observations with the Very Large Array (VLA) show that a part of the emission originates from two prominent sites of star formation that are associated with compact radio continuum sources, likely ultra-compac

Vladimir Yurchenko

We analyze the polarization properties of the tilted off-axis dual-reflector submillimeter-wave telescope on the ESA PLANCK Surveyor designed for measuring the temperature anisotropies and polarization characteristics of the cosmic microwave background.

Abhas Mitra

There are many observational evidences for the existence of massive compact condensations in the range $10^6 -10^{10} M_\odot$ at the core of various galaxies. At present such condensations are commonly interpreted as Black Holes (BHs). However, we point out that while such Black Hole Candidates (BHCs) must be similar to BHs in many respects they, actually,

B. F. Liu, S. Mineshige, K. Shibata

We construct a simple model for a magnetic reconnection heated corona above a thin accretion disk in AGNs and Galactic black hole candidates(GBHCs). The basic assumptions are that (1) the magnetic reconnection heat is cooled down overwhelmingly by Compton scattering in the corona and that (2) thermal conduction is dominantly cooled by evaporation of the chro

F. Royer, S. Grenier, M. -O. Baylac, A. E. Gomez

This work is the second part of the set of measurements of vsini for A-type stars, begun by Royer et al. (2002). Spectra of 249 B8 to F2-type stars brighter than V=7 have been collected at Observatoire de Haute-Provence (OHP). Fourier transforms of several line profiles in the range 4200--4600 A are used to derive vsini from the frequency of the first zero.

Laura Maraschi, Fabrizio Tavecchio

We discuss the relation between the power carried by relativistic jets and the nuclear power provided by accretion, for a group of blazars including FSRQs and BL Lac objects. They are characterized by good quality broad band X-ray data provided by the Beppo SAX satellite. The jet powers are estimated using physical parameters determined from uniformly modell

J. Guy, P. Vincent, J. P. Tavernet, M. Rivoal

The KASKADE and CORSIKA air shower generators are compared to the data collected by MASS2 balloon experiment in 1991. The test of longitudinal profile for proton, helium and muon flux production provide good constraints on these air shower generators. KASKADE and CORSIKA especially with the new simulator UrQMD for low energies are found to fit these data wel

S. I. Ipatov

A considerable portion of near-Earth objects could have come from the trans-Neptunian belt. Some of them have aphelia deep inside Jupiter&#39;s orbit during more than 1 Myr.

G. Mark Voit, Greg L. Bryan, Michael L. Balogh, Richard G. Bower

We present a set of cluster models that link the present-day properties of clusters to the processes that govern galaxy formation. These models treat the entropy distribution of the intracluster medium as its most fundamental property. Because convection strives to establish an entropy gradient that rises with radius, the observable properties of a relaxed c

Andrew Bunker, Hyron Spinrad, Ross McLure, Arjun Dey

We present high-resolution imaging in the rest-frame optical of the weak radio source LBDS53W091. Previous optical spectroscopy has shown that this object has an evolved stellar population of age >3Gyr at z=1.55, determined from the amplitude of rest-frame UV spectral breaks. We have obtained deep Hubble Space Telescope imaging over 10 orbits with NICMOS cam

Rolando Cardenas, Osmel Martin, Israel Quiros

We briefly comment on a paper by Rubano and Scudellaro [astro-ph/0103335] where they found general exact solutions for two classes of exponential potentials in a scalar field model for quintessence. In that paper the authors were led to some interesting conclusions after a proper choice of the integration constants. By using dimensionless variables we show t

Krzysztof Belczynski, Tomasz Bulik

Using the StarTrack population synthesis code we analyze the possible formation channels of the Galactic microquasar GRS 1915+105 harboring the most massive known stellar black hole. We find that we are able to reproduce the evolution and the current state of GRS 1915+105 in a model with lowered wind mass loss rates in massive stars. We conclude that the exi

L. V. Panina, A. N. Grigorenko, D. P. Makhnovskiy

A new type of metal-dielectric composites has been proposed that is characterised by a resonance-like behaviour of the effective permeability in the infrared and visible spectral ranges. This material can be referred to as optomagnetic medium. The analytical formalism developed is based on solving the scattering problem for considered inclusions with impedan