January 2001 arXiv papers — page 7

S. Chiantese

Using the higher covariant derivatives regularization of gauge theories in the framework of the background field method, supplemented with one-loop Pauli-Villars regulator fields, we obtain a version of the renormalization group equation for the regulator fields, whose vacuum energy depends on the background gauge field. It is evaluated using an anomalous Wa

Jaroslaw Kijak

The paper presents a comparison of emission altitudes in very young and very old radio pulsars. The author confirmes that altitudes at which radio emission at a given frequency is generated depend on pulsar period and on pulsar age, although the latter dependence is quite weak.

Abhijit Bandyopadhyay, Sandhya Choubey, Srubabati Goswami

We investigate the solar neutrino problem assuming simultaneous presence of MSW transitions in the sun and neutrino decay on the way from sun to earth. We do a global $χ^2$-analysis of the data on total rates in Cl, Ga and Superkamiokande (SK) experiments and the SK day-night spectrum data and determine the changes in the allowed region in the $\dm - \tan^2θ

M. Wellmann

In the framework of causal perturbation theory we consider a massive scalar field coupled to gravity. In the field theoretic approach to quantum gravity (QG) we start with a massless second rank tensor field. This tensor field is then quantized in a covariant way in Minkowski space. This article deals with the adiabatic limit for graviton radiative correctio

P. L. Krotkov, V. P. Mineev, G. A. Vermeulen

We study spin dynamics of a normal Fermi liquid taking into account the demagnetizing field produced by the spin system itself. Linear solutions of the spin dynamics equations in the form of standing spin waves in a finite volume of liquid are found. At almost all known experimental conditions the influence of demagnetizing field can be satisfactorily descri

Edward V. Shuryak

We argue that if the growing part of hadron-hadron cross section (described phenomenologically by the supercritical soft Pomeron) is due to instanton/sphaleron mechanism, one should find certain qualitative features of the produced cluster which differ from the usual string fragmentation. Furthermore, we suggest that this mechanism should be even more import

Gunnar Bjork, Luis L. Sanchez Soto, Jonas Soderholm

We demonstrate a systematic approach to sub-wavelength resolution lithographic image formation on films covering areas larger than a wavelength squared. For example, it is possible to make a lithographic pattern with a feature size resolution of $λ/[2(N+1)]$ by using a particular $2 M$-photon, multi-mode entangled state, where $N < M$, and banks of birefring

Marc-Thierry Jaekel, Serge Reynaud

Quantum algebraic observables representing localization in space-time of a Dirac electron are defined. Inertial motion of the electron is represented in the quantum algebra with electron mass acting as the generator of motion. Since transformations to uniformly accelerated frames are naturally included in this conformally invariant description, the quantum a

Samuel J. Lomonaco

This paper gives an overview from the perspective of Lie group theory of some of the recent advances in the rapidly expanding research area of quantum entanglement. This paper is a written version of the last of eight one hour lectures given in the American Mathematical Society (AMS) Short Course on Quantum Computation held in conjunction with the Annual Mee

Gerhard Kramer, Serap A. Savari

We provide a rate distortion interpretation of the problem of quantum data compression of ensembles of mixed states with commuting density operators. There are two versions of this problem. In the visible case the sequence of states is available to the encoder and in the blind or hidden case the encoder may access only a sequence of measurements. We find the

Giuseppe Nistico&#39;, Roberto Beneduci

We introduce a new notion of consistency for 2-events quantum histories, based on the concept of mirror projection. Contrary to all notions of consistency so far introduced, our consistency, named self-decoherence, is an individual property, i.e., it can be attributed to every single sample of the physical system. Furthermore, self-decoherence forbids contra

M. Dorado

Using Euler&#39;s equations of motion and the Hamiltonian formulation, we obtain the equations of motion of systems with internal angular momentum that are moving with respect to a given reference frame, when subjected to a torque which is permanently perpendicular to the angular momentum vector.

A. M. Gevorkian, R. A. Gevorkian

The paper discusses some aspects of real physical space and time: structure of electrodynamics; structure of gravitational-inert theory in the real world; formation of the real matter; Mach&#39;s principle and the radiational cosmic mass; spread and transmission of information in the space of the real world; fundamental and main physical constants, protostar

Huping Hu, Maoxin Wu

Although more than 150 years have past since the discovery of general anesthetics, how they precisely work remains a mystery. We propose a novel unitary mechanism of general anesthesia verifiable by experiments. In the proposed mechanism, general anesthetics perturb oxygen pathways in both membranes and oxygen-utilizing proteins such that the availabilities

Thomas R. Hemmert

Following up on the plenary talk given by Ulf Meißner, I discuss a generalization of the concept of nucleon spin-polarizabilities in terms of multipole excitation/de-excitation and present an overview of the available theoretical predictions for these elusive but interesting structure parameters of the nucleon.

Thomas R. Hemmert

Chiral effective field theories have a long history studying the process of Compton scattering on the nucleon. In this contribution I want to focus on the new developments that have occured since the last Chiral Dynamics conference in Mainz 1997. I will focus exclusively on the spin-dependent sector, where most of the recent work has been done.

P. K. Deb, K. Amos, S. Karataglidis, M. B. Chadwick

Nucleon total reaction and neutron total cross sections to 300 MeV for 12C and 208Pb, and for 65 MeV spanning the mass range, are predicted using coordinate space optical potentials formed by full folding of effective nucleon-nucleon interactions with realistic nuclear ground state densities. Good to excellent agreement is found with existing data.

Norbert Kaiser

We calculate in (two-loop) chiral perturbation theory the local NN-potentials generated by the three-pion exchange diagrams with one insertion from the second order chiral effective pion-nucleon Lagrangian proportional to the low-energy constants $c_{1,2,3,4}$. The resulting isoscalar central potential vanishes identically. In most cases these $3π$-exchange

K. Wisniewski, P. Crochet, N. Herrmann

The ratio of K- to K+ meson yields has been measured in the systems RuRu at 1.69 A GeV, Ru+Zr at 1.69 A GeV, and Ni+Ni at 1.93 A GeV incident beam kinetic energy. The yield ratio is observed to vary across the measured phase space. Relativistic transport-model calculations indicate that the data are best understood if in-medium modifications of the kaons are

Steve Shkoller

We study the coupled Navier-Stokes Ginzburg-Landau model of nematic liquid crystals introduced by F.H. Lin, which is a simplified version of the Ericksen-Leslie system. We generalize the model to compact n-dimensional Riemannian manifolds, and show that the system comes from a variational principle. We present a new simple proof for the local well-posedness

Nikolaj M. Glazunov

We present some methods and results in the application of algebraic geometry and computer algebra to the study of algebraic vector bundles, foliations and zeta functions. A connection of the methods and results with noncommutative geometry will be consider.

Stefan Rönn

This treatise investigates holomorphic functions defined on the space of bicomplex numbers introduced by Segre. The theory of these functions is associated with Fueter&#39;s theory of regular, quaternionic functions. The algebras of quaternions and bicomplex numbers are developed by making use of so-called complex pairs. Special attention is paid to singular

Jesus Araujo, Juan J. Font

Let M be a complete metric space. It is proved that if the space or scalar-valued bounded continuous functions on M admits an isometric shift, then M is separable.

Frederic Campana, Thomas Peternell

We investigate the universal cover of projective threefolds whose tangent bundle is a direct sum of subbundles in case the Kodaira dimension is not 1 and 2. We also prove results on Fano manifolds with splitting tangent bundles in any dimension.

Y. M. Eliashberg, N. M. Mishachev

In 1969 M. Gromov in his PhD thesis greatly generalized Smale-Hirsch-Phillips immersion-submersion theory by proving what is now called the h-principle for invariant open differential relations over open manifolds. Gromov extracted the original geometric idea of Smale and put it to work in the maximal possible generality. Gromov&#39;s thesis was brought to t

Yu. I. Zhuraev, F. Sharipov

In the present paper the notion of a Hilbert module over a locally C*-algebra is discussed and some results are obtained on this matter. In particular, we give a detailed proof of the known result that the set of adjointable endomorphisms of such modules is itself a locally C*-algebra.

Jaya N. Iyer

In this article, we show that very ample line bundles of type (1,1,d) on an abelian threefold A, with NS(A)\simeq \ze, give projectively normal embeddings, if d=22,26 or when d\geq 28.

G. de Berredo-Peixoto, I. L. Shapiro

We construct a new example of the high derivative four-dimensional conformal operator. This operator acts on fermions, and its contribution to the trace anomaly has opposite sign, as compared to conventional scalars, spinors and vectors. Possible generalizations and applications are discussed.

August Romeo, Aram A. Saharian

The Casimir effect for general Robin conditions on the surface of a cylinder in $D$-spacetime dimensions is studied for massive scalar field with general curvature coupling. The energy distribution and vacuum stress are investigated. We separate volumic and superficial energy contributions, for both interior and exterior space regions. The possibility that s

Roberto Casadio, Benjamin Harms

We study the evaporation of black holes in space-times with extra dimensions of size L. We first obtain a description which interpolates between the expected behaviors of very large and very small black holes and then show that the luminosity is greatly damped when the horizon shrinks towards L from a larger value. Analogously, black holes born with an initi

Christian Rupp, Rainer Scharf, Klaus Sibold

In the Wess-Zumino gauge, supersymmetry transformations become non-linear and are usually incorporated together with BRS transformations in the form of Slavnov-Taylor identities, such that they appear at first sight to be even non-local. Furthermore, the gauge fixing term breaks supersymmetry. In the present paper, we clarify in which sense supersymmetry is

J. F. Vazquez-Poritz

We consider five-dimensional domain-wall solutions which arise from a sphere reduction in M-theory or string theory and have the higher-dimensional interpretation as the near-horizon region of p-branes in constant, background B fields. We analyze the fluctuation spectrum of linearized gravity and find that there is a massive state which is localized and play

Robert L. Jaffe

I review the progress in fundamental spin physics over the past several years and the prospects for the future. The progress is striking and the prospects are excellent.

Thomas G. Rizzo

In the model of Arkani-Hamed and Schmaltz the various chiral fermions of the Standard Model(SM) are localized at different points on a thick wall which forms an extra dimension. Such a scenario provides a way of understanding the absence of proton decay and the fermion mass hierarchy in models with extra dimensions. In this paper we explore the capability of

Elvio Di Salvo

We consider two different spin asymmetries in Drell-Yan processes generated by the collisions of an unpolarized proton beam on transversely polarized protons: the muon helicity asymmetry and the left-right asymmetry. We calculate the asymmetries in the framework of the QCD improved parton model, taking into account the parton transverse momentum and consider

Robert Fleischer, Thomas Mannel

We present a model-independent parametrization of the $B^\pm\to J/ψK^\pm$, $B_d\to J/ψK_S$ decay amplitudes by taking into account the constraints that are implied by the isospin symmetry of strong interactions. Employing estimates borrowed from effective field theory, we explore the impact of physics beyond the Standard Model and introduce -- in addition to

E. E. Boos

In theories like SM or MSSM with a complex gauge group structure the complete set of Feynman diagrams contributed to a particular physics process can be splited to exact gauge invariant subsets. Arguments and examples given in the review demonstrate that in many cases computations and analysis of the gauge invariant subsets are important.

M. Chaichian, K. Huitu, Z. -H. Yu

We study the single production of scalar neutrinos or charginos via $γγ$ collision in an R-parity ($R_{p}$) violating supersymmetric model. It may be possible to detect a sneutrino or a chargino at a Linear Collider (LC) in $γγ$ operation mode, as a test of supersymmetry and $R_p$-violation. Because of the clean background in LC, stringent constraints on $R_

T. Kopaleishvili

Five different versions of the three-dimensional (3D) reduction of the Bethe-Salpeter (BS) equation in the instantaneous approximation for kernel of BS equation for the two-fermion systems are formulated. The normalization condition for the bound-state wave function in all versions are derived. Further, the 3D reduction of BS equation without instantaneous a

A. V. Radyushkin

In these lectures, I describe the techniques used within the QCD sum rule approach. The basic concepts of the approach are introduced using a simple model of quantum-mechanical oscillator in 2+1 dimensions. Then I discuss their field-theoretical extension and the construction of the operator product expansion for current correlators in QCD. The calculation o

Edward K. G. Sarkisyan

A review on recent investigations of local fluctuations and genuine correlations in electron-positron annihilations at LEP and in positron-proton collisions at HERA is given.

R. Prigl, Muon g-2 Collaboration

The muon g-2 experiment at Brookhaven has been taking data since 1997. Analyses of the data taken in 1997 and 1998, which include about 2% of the data taken so far, have improved the experimental accuracy in the muon anomalous magnetic moment to a(mu,expt) = 1 165 921(5) x 10**(-9) (4 ppm). The value agrees with standard theory. Analysis of the 1999 data, ab

P. Antonioli, MONOLITH Collaboration

MONOLITH is a massive magnetized tracking calorimeter, optimized for the detection of atmospheric muon neutrinos, proposed at the Gran Sasso laboratory in Italy. The main goal is to establish (or reject) the neutrino oscillation hypothesis through an explicit observation of the full first oscillation swing (the ``L/E pattern&#39;&#39;). Its performance, stat

Raja Nandakumar

Colour reconnection is the final state interaction between quarks from different sources. It is not yet fully understood and is a source of systematic error for W-boson mass and width measurements in hadronic \WW decays at LEP2. The methods of measuring this effect and the results of the 4 LEP experiments at $183\gev\leq\rts\leq 202\gev$ will be presented.

Claus Lämmerzahl, Christian J. Bordé

The dynamical equations which are basic for the description of the dynamics of quantum felds in arbitrary space--time geometries, can be derived from the requirements of a unique deterministic evolution of the quantum fields, the superposition principle, a finite propagation speed, and probability conservation. We suggest and describe observations and experi

Morteza Mohseni

It is shown that a change in the signature of the space-time metric together with compactification of internal dimensions could occure in a six-dimensional cosmological model. We also show that this is due to interaction with Maxwell fields having support in the internal part of the space-time.

Parampreet Singh, Naresh Dadhich

From the relativistic law of motion we attempt to deduce the field theories corresponding to the force law being linear and quadratic in 4-velocity of the particle. The linear law leads to the vector gauge theory which could be the abelian Maxwell electrodynamics or the non-abelian Yang-Mills theory. On the other hand the quadratic law demands spacetime metr

Peter Gacs

Consider a network of processors (sites) in which each site x has a finite set N(x) of neighbors. There is a transition function f that for each site x computes the next state ξ(x) from the states in N(x). But these transitions (updates) are applied in arbitrary order, one or many at a time. If the state of site x at time t is η(x,t) then let us define the s

Ming-Yang Kao, Stephen R. Tate

In this paper we examine problems motivated by on-line financial problems and stochastic games. In particular, we consider a sequence of entirely arbitrary distinct values arriving in random order, and must devise strategies for selecting low values followed by high values in such a way as to maximize the expected gain in rank from low values to high values.

Paul B. Rundle, John B. Rundle, Kristy F. Tiampo, Jorge S. Sa Martins

Earthquake faults occur in networks that have dynamical modes not displayed by single isolated faults. Using simulations of the network of strike-slip faults in southern California, we find that the physics depends critically on both the interactions among the faults, which are determined by the geometry of the fault network, as well as on the stress dissipa

Ronald Dickman, Mikko Alava, Miguel A. Munoz, Jarkko Peltola

We study a one-dimensional fixed-energy version (that is, with no input or loss of particles), of Manna&#39;s stochastic sandpile model. The system has a continuous transition to an absorbing state at a critical value $ζ_c$ of the particle density. Critical exponents are obtained from extensive simulations, which treat both stationary and transient propertie

Maziar Nekovee, Peter V. Coveney

We report the first results of our three-dimensional, mesoscopic, amphiphilic lattice-Boltzmann model, which has been used to simulate the dynamics of self-assembly of ordered cubic and lamellar phases in binary water-surfactant systems. Our results provide insight into the mechanism of ordering of such mesophases in terms of various molecular forces acting

A. Engel

It is shown that the experimental results reported in cond-mat/0010412 do not invalidate the well-known expression for the Kelvin force density in ferrofluids.

A. Soubret, G. Berginc, C. Bourrely

The problem of an electromagnetic wave scattering by a slab with two rough boundaries is solved by a small-perturbation method under the Rayleigh hypothesis. In order to obtain a perturbative development, we use a systematic procedure which involves integral equations called the reduced Rayleigh equations. Then we will show for a dielectric slab deposited on

Y. Malevergne, D. Sornette

We extend the model of rational bubbles of Blanchard and of Blanchard and Watson to arbitrary dimensions d: a number d of market time series are made linearly interdependent via d times d stochastic coupling coefficients. We first show that the no-arbitrage condition imposes that the non-diagonal impacts of any asset i on any other asset j different from i h

Amandine Aftalion, Qiang Du

In this paper, we provide the different types of bifurcation diagrams for a superconducting cylinder placed in a magnetic field along the direction of the axis of the cylinder. The computation is based on the numerical solutions of the Ginzburg-Landau model by the finite element method. The response of the material depends on the values of the exterior field

F. Tzschichholz, M. Wangen

We review microstructural fracture growth models suitable for the study of hydraulic fracture processes in disordered porous materials and present some basic results. It is shown that microstructural models exhibit certain similarities to corresponding theories of continua. These similarities are most easily demonstrated for simple crack geometries, i.e., st

M. Minakata, Y. Maeno

We report unusual effects of nonmagnetic impurities on the spin-triplet superconductor Sr2RuO4. The substitution of nonmagnetic Ti4+ for Ru4+ induces localized-moment magnetism characterized by unexpected Ising anisotropy with the easy axis along the interlayer c direction. Furthermore, for x(Ti) > 0.03 magnetic ordering occurs in the metallic state with the

M. -Carmen Miguel, R. Pastor-Satorras

We study non-equilibrium velocity fluctuations in a model for the sedimentation of non-Brownian particles experiencing long-range hydrodynamic interactions. The complex behavior of these fluctuations, the outcome of the collective dynamics of the particles, exhibits many of the features observed in sedimentation experiments. In addition, our model predicts a

Avner Peleg, Baruch Meerson, Arkady Vilenkin, Massimo Conti

A long and slender finger can serve as a simple ``test bed&#39;&#39; for different phase ordering models. In this work, the globally-conserved, interface-controlled dynamics of a long finger is investigated, analytically and numerically, in two dimensions. An important limit is considered when the finger dynamics are reducible to the area-preserving motion b

Akito Kobayashi, Atsushi Tsuruta, Tamifusa Matsuura, Yoshihiro Kuroda

High-Tc superconducting materials (HTSC) have anomalous properties such as the pseudo-gap or spin-gap etc., in Hall coefficient, 1/T1T and the density of states etc. First including effects of strong on-site repulsion between d-electrons at Cu-sites, we obtain quasi-particles with super-exchange interaction Js, whose band width tends to zero, i.e., the syste

Jones T. K. Wan, K. W. Yu, G. Q. Gu

We consider a two-particle system in which a particle is held fixed, and the other one rotates around the axis perpendicular to the line joining the particles centers. The rotating particle leads to a displacement of its polarization charge on the surface. Our results show that the rotational motion of the particles generally reduces the force between the pa

C. K. Lo, Jones T. K. Wan, K. W. Yu

We have applied the Ewald-Kornfeld formulation to a tetragonal lattice of point dipoles, in an attempt to examine the effects of geometric anisotropy on the local field distribution. The various problems encountered in the computation of the conditionally convergent summation of the near field are addressed and the methods of overcoming them are discussed. T

John T. Stocke

I describe two difficulties with current research into the cosmic evolution of BL Lacertae Objects: (1). Possible sample incompleteness due to unrecognized (i.e., ``hidden&#39;&#39;) BL Lacs; and (2). The absence of a viable physical model of the evolution, to which current and future observations can be compared.

Christopher P. O&#39;Dea, Anton M. Koekemoer, Stefi A. Baum, William B. Sparks

We present new HST STIS/MAMA near-UV images and archival WFPC2 V and R band images which reveal the presence of four star forming regions in an arc along the edge of the dust lane in the giant (4 Mpc) radio galaxy 3C236. Two of the star forming regions are relatively young with ages of order 1E7 yr, while the other two are older with ages of order 1E8 - 1E9

J. W. Truran, J. J. Cowan, B. D. Fields

We review recent observational studies of heavy element abundances in low metallicity stars and explore some implications of these results for nucleosynthesis and early Galactic chemical evolution.

C. Sneden, J. J. Cowan, J. W. Truran

In a brief review of abundances neutron-capture elements (Z > ~30) in metal-poor halo stars, attention is called to their star-to-star scatter, the dominance of r-process synthesis at lowest metallicities, the puzzle of the lighter members of this element group, and the possibility of a better r-/s-process discriminant.

J. J. Cowan, C. Sneden, J. W. Truran

Observations of metal-poor Galactic halo stars indicate that the abundance pattern of the (heaviest) neutron-capture elements is consistent with the scaled solar system r-process abundances. Utilizing the radioactive (r-process) element thorium, age determinations have been made for several of these same stars, placing constraints on both Galactic and cosmol

L. Guzzo, A. Moretti, S. Campana, S. Covino

We briefly describe the main features of the Brera Multi-Wavelet (BMW) survey of serendipitous X-ray clusters, based on the still unexploited ROSAT-HRI archival observations. Cluster candidates are selected from the general BMW catalogue of 20,000 sources based exclusively on their X-ray extension. Contrary to common wisdom, a clever selection of the HRI ene

Patrick R. Durrell, William E. Harris, Christopher J. Pritchet

We have conducted a wide-field CCD-mosaic study of the resolved red-giant branch (RGB) stars of M31, in a field located 20 kpc from the nucleus along the SE minor axis. In our (I, V-I) color-magnitude diagram, RGB stars in the top three magnitudes of the M31 halo are strongly present. Photometry of a more distant control field to subtract field contamination

Bennett Link, Richard I. Epstein

Pulse timing of the isolated pulsar PSR B1882-11 shows strong Fourier power at periods ~1000, 500 and 250 d, correlated with changes in the pulse profile (Stairs, Lyne & Shemar 2000). We study the extent to which these data can be explained by precession of the star&#39;s rigid crust coupled to the magnetic dipole torque. We find that the correlated changes

J. Klare, J. A. Zensus, T. P. Krichbaum, A. P. Lobanov

The quasar 3C345 is one of the best examples of extragalactic jet with superluminal components moving on helical paths. To get better constraints on the jet physics, we have imaged the source at the highest possible resolution, using mm-VLBI and space-VLBI observations. We observed 3C345 at 5 different epochs so far (1 epoch with 3-mm ground VLBI, and 4 epoc

R. Ramaty, R. E. Lingenfelter, B. Kozlovsky

We discuss the highlights of our recent research, specifically the refractory vs. volatile interpretation of the rise of [O/Fe] with decreasing [Fe/H], and the issue of primary vs. secondary evolution of Be.

Meghan E. Gray, Richard S. Ellis, James R. Lewis, Richard G. McMahon

We present a deep H-band image of the region in the vicinity of the cluster Abell 1942 containing the puzzling dark matter concentration detected in an optical weak lensing study by Erben et al. (2000). We demonstrate that our limiting magnitude, H=22, would be sufficient to detect clusters of appropriate mass out to redshifts comparable with the mean redshi

Francesca Perrotta, Carlo Baccigalupi, Matthias Bartelmann, Gianfranco De Zotti

We present detailed calculations of the magnification distribution, including both weak and strong lensing, using very recent solutions of the Dyer-Roeder (1973) equation for light propagation in a inhomogeneous universe with a cosmological constant and up-to-date models for the evolving cosmological distribution of dark matter halos. We address in particula

M. Scodeggio, A. Zanichelli, B. Garilli, O. Le Fevre

VIMOS main distinguishing characteristic is its very high multiplex capability: in MOS mode up to 800 spectra can be acquired simultaneously, while the Integral Field Unit produces 6400 spectra to obtain integral field spectroscopy of an area approximately 1x1 arcmin in size. To successfully exploit the capabilities of such an instrument it is necessary to e

H. Papathanassiou

The energy spectra of pulses of GRBs are modeled for synchrotron and multiple self-inverse Compton scatterings from a population of thermal and non-thermal $e^-$s. The contribution from pairs that result from annihilation is also taken into account. A high particle density (enhanced by the pairs) will increase absorption but, if the pairs are not accelerated

T. Berkefeld, A. Glindemann, S. Hippler

In order to increase the corrected field of view of an adaptive optics (AO) system, several deformable mirrors (DM) have to be placed in the conjugate planes of the dominant turbulent layers (multi-conjugate adaptive optics, MCAO [Beckers et al.]). The performance of MCAO systems depends on the quality of the wavefront sensing of the individual layers and on

J. U. Fynbo, B. L. Jensen, J. Gorosabel, J. Hjorth

We present the discovery of the optical transient of the long-duration gamma-ray burst GRB000630. The optical transient was detected with the Nordic Optical Telescope 21.1 hours after the burst. At the time of discovery the magnitude of the transient was R = 23.04+-0.08. The transient displayed a power-law decline characterized by a decay slope of alpha = -1

Stefanie Komossa

(abridged) MR2251-178 was the first quasar initially discovered in X-rays, and the first one found to host a warm absorber. The quasar turned out to be an outstanding object in many respects. It has a high ratio of X-ray/optical luminosity, is surrounded by the largest quasar emission-line nebula known, and is located in the outskirts of a cluster of galaxie

Torsten Ekedahl, Trygve Johnsen, Dag Einar Sommervoll

We study each of the 16 types of complete intersection Calabi-Yau threefolds in projective n-space times the projective line, for various n, and prove existence of isolated rational curves of bidegree (d,0) for all positive integers d on a general threefold of each of these types. As a corollary we find isolated rational curves in all degrees on a general CI

A. Katrin Schenk, Phil Arras, Eanna E. Flanagan, Saul A. Teukolsky

We develop the formalism required to study the nonlinear interaction of modes in rotating Newtonian stars in the weakly nonlinear regime. The formalism simplifies and extends previous treatments. At linear order, we elucidate and extend slightly a formalism due to Schutz, show how to decompose a general motion of a rotating star into a sum over modes, and ob

Jean-Luc Thiffeault, P. J. Morrison

We describe a new type of top, the twisted top, obtained by appending a cocycle to the Lie-Poisson bracket for the charged heavy top, thus breaking its semidirect product structure. The twisted top has an integrable case that corresponds to the Lagrange (symmetric) top. We give a canonical description of the twisted top in terms of Euler angles. We also show

Gregory Laughlin, John E. Chambers

We show that short-term perturbations among massive planets in multiple planet systems can result in radial velocity variations of the central star which differ substantially from velocity variations derived assuming the planets are executing independent Keplerian motions. We discuss two alternate fitting methods which can lead to an improved dynamical descr

J. E. McClintock, M. R. Garcia, N. Caldwell, E. E. Falco

Observations of the quiescent X-ray nova XTE J1118+480 with the new 6.5-m MMT have revealed that the velocity amplitude of the dwarf secondary is 698 +/- 14 km/s and the orbital period of the system is 0.17013 +/- 0.00010 d. The implied value of the mass function, f(M) = 6.00 +/- 0.36 solar masses, provides a hard lower limit on the mass of the compact prima

C. Panagiotakopoulos, A. Pilaftsis

A possible discovery of a relatively light charged Higgs boson H^+ in near future experiments, with a mass M_{H+} ~< 110 GeV, together with the present LEP2 direct limits on the chargino and neutral Higgs sectors, would disfavour the minimal supersymmetric standard model as well as its frequently discussed next-to-minimal supersymmetric extension. We show th

D. Jido, E. Oset, J. E. Palomar

We take an approach to the Lambda non-mesonic weak decay in nuclei based on the exchange of mesons. The one pion and one kaon exchange are considered, together with the exchange of two pions, either correlated, leading to an important scalar-isoscalar exchange (sigma-like exchange), or uncorrelated (box diagrams). Extra effects of omega exchange in the scala

Romeel Davé, Todd M. Tripp

We examine the Ly-alpha absorber population at z<0.3 detected in spectra of the QSOs PG0953+415 and H1821+643 taken with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. We compare their statistical properties to those in carefully-constructed mock quasar spectra drawn from a cosmological hydrodynamic simulation of a Lambda-CDM uni

Nobuya Maeshima, Yasuhiro Hieida, Yasuhiro Akutsu, Tomotoshi Nishino

We present a new algorithm to calculate the thermodynamic quantities of three-dimensional (3D) classical statistical systems, based on the ideas of the tensor product state and the density matrix renormalization group. We represent the maximum-eigenvalue eigenstate of the transfer matrix as the product of local tensors which are iteratively optimized by the

Louise M Griffiths, Alessandro Melchiorri, Joseph Silk

In recent years, upper limits on the cosmic microwave background (CMB) anisotropies combined with predictions made by theories of galaxy formation, have been extremely powerful in ruling out purely baryonic dark matter (BDM) universes. However, it has recently been argued that the absence of a prominent second peak in the anisotropy spectrum measured by the

Stephen G. Low

The unitary irreducible representations of the covering group of the Poincare group P define the framework for much of particle physics on the physical Minkowski space P/L, where L is the Lorentz group. While extraordinarily successful, it does not provide a large enough group of symmetries to encompass observed particles with a SU(3) classification. Born pr

S. Capozziello, G. Lambiase, H. -J. Schmidt

For a spatially flat Friedmann model with line element $ds^2=a^2 [ da^2/B(a)-dx^2-dy^2-dz^2 ] $, the 00-component of the Einstein field equation reads $8πG T_{00}=3/a^2$ containing no derivative. For a nonlinear Lagrangian ${\cal L}(R)$, we obtain a second--order differential equation for $B$ instead of the expected fourth-order equation. We discuss this equ

Xavier Tolsa

In this paper we develop a kind of A_p theory for Calderon-Zygmund operators in a non-homogeneous setting. Let μbe a Borel measure on \R^d which may be non doubling. The only condition that μmust satisfy is μ(B(x,r))\leq Cr^n for all x\in\R^d, r>0 and for some fixed n with 0<n\leq d. We introduce a maximal operator N, which coincides with the maximal Hardy-L

V. B. Petkova, J. -B. Zuber

We define generalised chiral vertex operators covariant under the Ocneanu ``double triangle algebra&#39;&#39; {\cal A}, a novel quantum symmetry intrinsic to a given rational 2-d conformal field theory. This provides a chiral approach, which, unlike the conventional one, makes explicit various algebraic structures encountered previously in the study of these

R. Mahendiran, B. Raveau, M. Hervieu, C. Michel

We show that metal-insulator transition in Pr0.5Ca0.5Mn1-xCrxO3 (x = 0.015-0.025) is unstable against thermal cycling. Insulator-metal transition shifts down and low temperature resistivity increases each time when the sample is cycled between a starting temperature TS and a final temperature TF. The effect is dramatic lower is x. Insulator-metal transition

Nir Barnea, Winfried Leidemann, Giuseppina Orlandini

The recently developed effective interaction method for the hyperspherical harmonic formalism is extended to noncentral forces. Binding energies and radii of three- and four-body nuclei are calculated with AV6 and AV14 NN potentials. Excellent results for the convergence of the expansion are found, particularly for the three-nucleon system. Due to the higher

B. Basu-Mallick, Bhabani Prasad Mandal

An exactly solvable many-particle quantum system is proposed by adding some nonhermitian but PT invariant interactions to the $B_N$ Calogero model. We have shown that such extended $B_N$ Calogero model leads to completely real spectrum which obey generalised exclusion statistics. It is also found that the corresponding exchange statistics parameter exhibit `

Samuel M Leach, Misao Sasaki, David Wands, Andrew R Liddle

We show that there exists a simple mechanism which can enhance the amplitude of curvature perturbations on superhorizon scales during inflation, relative to their amplitude at horizon crossing. The enhancement may occur even in a single-field inflaton model, and occurs if the quantity $a\dotϕ/H$ becomes sufficiently small, as compared to its value at horizon

I. Brevik, K. Pettersen

The Casimir effect is considered for a wedge with opening angle $α$, with perfectly conducting walls, when the interior region is filled with an isotropic and nondispersive medium with permittivity $ε$ and permeability $μ$. The electromagnetic energy-momentum tensor in the bulk is calculated, together with the surface stress on the walls. A discussion is giv

M. R. Setare, A. A. Saharian

The creation of massless scalar particles from the quantum vacuum by spherical shell with time varying radius is studied. In the general case of motion the equations are derived for the instantaneous basis expansion coefficients. The examples are considered when the mean number of particles can be explicitly evaluated in the adiabatic approximation.