July 1999 arXiv papers — page 20

Charles P. Boyer, Krzysztof Galicki

After observing that the well-known convexity theorems of symplectic geometry also hold for compact contact manifolds with an effective action of a torus whose Reeb vector field corresponds to an element of the Lie algebra of the torus, we use this fact together with a recent symplectic orbifold version of Delzant's theorem due to Lerman and Tolman [LT]

Andre Peshier, Markus H. Thoma

Under very general assumptions we show that the quark dispersion relation in the quark-gluon plasma is given by two collective branches, of which one has a minimum at a non-vanishing momentum. This general feature of the quark dispersion relation leads to structures (van Hove singularities, gaps) in the low mass dilepton production rate, which might provide

M. Bachmann, H. Kleinert, A. Pelster

We present a method for a recursive graphical construction of Feynman diagrams with their correct multiplicities in quantum electrodynamics. The method is first applied to find all diagrams contributing to the vacuum energy from which all n-point functions are derived by functional differentiation with respect to electron and photon propagators, and to the i

Sven Soff, Steffen A. Bass, Marcus Bleicher, Larissa Bravina

The centrality dependence of (multi-)strange hadron abundances is studied for Pb(158 AGeV)Pb reactions and compared to p(158 GeV)Pb collisions. The microscopic transport model UrQMD is used for this analysis. The predicted Lambda/pi-, Xi-/pi- and Omega-/pi- ratios are enhanced due to rescattering in central Pb-Pb collisions as compared to peripheral Pb-Pb or

Shamit Kachru, Jason Kumar, Eva Silverstein

We discuss the fate of certain tachyonic closed string theories from two perspectives. In both cases our approach involves studying directly configurations with finite negative tree-level cosmological constant. Closed string analogues of orientifolds, which carry negative tension, are argued to represent the minima of the tachyon potential in some cases. In

A. Echeverría-Enríquez, M. C. Muñoz-Lecanda, N. Román-Roy

We state the intrinsic form of the Hamiltonian equations of first-order Classical Field theories in three equivalent geometrical ways: using multivector fields, jet fields and connections. Thus, these equations are given in a form similar to that in which the Hamiltonian equations of mechanics are usually given. Then, using multivector fields, we study sever

Ali H. Chamseddine

An action for supersymmetric D0-branes in curved backgrounds is obtained by dimensional reduction of N=1 ten-dimensional supergravity coupled to super Yang-Mills system to 0+1 dimensions. The resultant action exhibits the coset-space symmetry $\frac{SO(9,9+n)}{SO(9)\times SO(9+n)}\times U(1)$ where $n=N^{2}-1$ is the dimension of the SU(N) gauge group.

Ekaterina Christova, Elliot Leader

We show that measurements of semi-inclusive $π^\pm$ asymmetries on $p$ and $n$ with polarized and unpolarized target and beams allow, without any knowledge of the polarized parton densities 1) to test independent fragmentation and SU(2) symmetry for the polarized sea, and 2) to determine separately the polarized strange and valence quark densities, and the r

S V Babak, L P Grishchuk

The search for the gravitational energy-momentum tensor is often qualified as an attempt of looking for ``the right answer to the wrong question''. This position does not seem convincing to us. We think that we have found the right answer to the properly formulated question. We have further developed the field theoretical formulation of the general r

M. Schumann, R. J. Lindebaum, R. D. Viollier

The non-divergent diagrams describing two-gluon exchange and annihilation between quarks and antiquarks are calculated in the Feynman gauge, based on quantum chromodynamics in a spherical cavity. Using the experimental $N$, $Δ$, $Ω$, and $ρ$ masses to fit the free parameters of the M.I.T.\ bag model, the predicted states agree very well with the observed low

M. E. Gomez, G. Lazarides, C. Pallis

The cosmological relic density of the lightest supersymmetric particle of the minimal supersymmetric standard model is calculated under the assumption of gauge and Yukawa coupling unification. We employ radiative electroweak breaking with universal boundary conditions from gravity-mediated supersymmetry breaking. Coannihilation of the lightest supersymmetric

Pedro F. Gonzalez-Diaz

In this paper the problem of the quantum stability of the two-dimensional warp drive spacetime moving with an apparent faster than light velocity is considered. We regard as a maximum extension beyond the event horizon of that spacetime its embedding in a three-dimensional Minkowskian space with the topology of the corresponding Misner space. It is obtained

Ian Smail, R. J. Ivison, F. N. Owen, A. W. Blain

We present deep radio maps from the Very Large Array (VLA) for 16 sources detected in a sub-millimeter (submm) survey of the distant Universe. Our deep VLA 1.4-GHz maps allow us to identify radio counterparts or place stringent limits (<20uJy in the source plane) on the radio flux of the submm sources. We compare the spectral indices of our sources between 8

Fritz Gesztesy

We provide an elementary approach to integrable systems associated with hyperelliptic curves of infinite genus. In particular, we explore the extent to which the classical Burchnall-Chaundy theory generalizes in the infinite genus limit, and systematically study the effect of Darboux transformations for the KdV hierarchy on such infinite genus curves. Our ap

A. Camacho

Resorting to a Gedankenexperiment which is very similar to the famous Aharonov-Bohm proposal it will be shown that, in the case of a Minkowskian spacetime, we may use a nonrelativistic quantum particle and a noninertial coordinate system and obtain geometric information of regions that are, to this particle, forbidden. This shows that the outcome of a nonrel

H. Barnum, C. M. Caves, J. Finkelstein, C. A. Fuchs

In a recent paper (quant-ph/9906015), Deutsch claims to derive the &#34;probabilistic predictions of quantum theory&#34; from the &#34;non-probabilistic axioms of quantum theory&#34; and the &#34;non-probabilistic part of classical decision theory.&#34; We show that his derivation fails because it includes hidden probabilistic assumptions.

G. N. Afanasiev, V. G. Kartavenko, Yu. P. Stepanovsky

We analyse the well-known Tamm problem treating the charge motion on a finite space interval with the velocity exceeding light velocity in medium. By comparing Tamm&#39;s formulae with the exact ones we prove that former do not properly describe Cherenkov radiation terms. We also investigate Tamm&#39;s formula cos(theta)=1/(beta n) defining the position of m

J. C. R. Bloch, V. A. Mizerny, A. V. Prozorkevich, C. D. Roberts

We solve the quantum Vlasov equation for fermions and bosons, incorporating spontaneous pair creation in the presence of back-reactions and collisions. Pair creation is initiated by an external impulse field and the source term is non-Markovian. A simultaneous solution of Maxwell&#39;s equation in the presence of feedback yields an internal current and elect

P. F. Kolb, J. Sollfrank, P. V. Ruuskanen, U. Heinz

We use a hydrodynamic model to study the space-time evolution transverse to the beam direction in ultrarelativistic heavy-ion collisions with nonzero impact parameters. We focus on the influence of early pressure on the development of radial and elliptic flow. We show that at high energies elliptic flow is generated only during the initial stages of the expa

P. J. Barneo, J. E. Amaro, A. M. Lallena

We present an approach to obtain new forms of the nuclear electromagnetic current, which is based on an integral form of the continuity equation. The procedure can be used to restore current conservation in model calculations in which the continuity equation is not verified. Besides, it provides, as a particular result, the so-called Siegert&#39;s form of th

L. Coraggio, A. Covello, A. Gargano, N. Itaco

We have performed shell-model calculations for the N=126 isotones 210Po, 211At, and 212Rn using a realistic effective interaction derived from the Bonn A nucleon-nucleon potential by means of a G-matrix folded-diagram method. The calculted binding energies, energy spectra and electromagnetic properties show remarkably good agreement with the experimental dat

K. Kaneko, M. Hasegawa

We study global features of proton-neutron (p-n) interactions and symmetry energy over a wide range of nuclei, using a schematic model interaction with four forces proposed recently. Calculations are performed by the BCS approximation in N,Z=20-50 and N,Z=50-82 regions. The experimental double differences of binding energies and symmetry energy are reproduce

S. De Bièvre, F. Germinet

We study the one-dimensional random dimer model, with Hamiltonian $H_ω=Δ+ V_ω$, where for all $x\in\Z, V_ω(2x)=V_ω(2x+1)$ and where the $V_ω(2x)$ are i.i.d. Bernoulli random variables taking the values $\pm V, V>0$. We show that, for all values of $V$ and with probability one in $ω$, the spectrum of $H$ is pure point. If $V\leq1$ and $V\neq 1/\sqrt{2}$, the

Arthur W. Apter, Joel David Hamkins

We show that if the weak compactness of a cardinal is made indestructible by means of any preparatory forcing of a certain general type, including any forcing naively resembling the Laver preparation, then the cardinal was originally supercompact. We then apply this theorem to show that the hypothesis of supercompactness is necessary for certain proof schema

Juan C. Migliore, Uwe Nagel

We show how to lift any monomial ideal J in n variables to a saturated ideal I of the same codimension in n+t variables. We show that I has the same graded Betti numbers as J and we show how to obtain the matrices for the resolution of I. The cohomology of I is described. Making general choices for our lifting, we show that I is the ideal of a reduced union

Joel David Hamkins, Daniel Evan Seabold

Infinite time Turing machines with only one tape are in many respects fully as powerful as their multi-tape cousins. In particular, the two models of machine give rise to the same class of decidable sets, the same degree structure and, at least for functions f:R-->N, the same class of computable functions. Nevertheless, there are infinite time computable fun

P. Akueson

We introduce the tangent space $ T({\rm H}_q) $ on the quantum hyperboloid ($ {\cal A}_{0,q}^c $) and equip it with an action on $ {\cal A}_{0,q}^c $ being a deformation of the action of vectors fields on functions. An embedding $ \displaystyle sl(2)_q \longrightarrow T({\rm H}_q) $ of $q$-deformed Lie algebra $ sl(2) $ being an analogue of the anchor $ \dis

Yucai Su, J. W. B. Hughes, R. C. King

To study finite-dimensional modules of the Lie superalgebras, Kac introduced the Kac-modules and divided them into typical or atypical modules according as they are simple or not. For Lambda being atypical, Hughes et al have an algorithm to determine all the composition factors of a Kac-module; they conjectured that there exists a bijection between the compo

A. Yu. Savin, B. Yu. Sternin

An elliptic theory is constructed for operators acting in subspaces defined via odd pseudodifferential projections. Subspaces of this type arise as Calderon subspaces for first order elliptic differential operators on manifolds with boundary, or as spectral subspaces for self-adjoint elliptic differential operators of odd order. Index formulas are obtained f

N. Aizawa

Polynomials of boson creation and annihilation operators which form irreducible tensor operators for Jordanian quantum algebra U_h(sl(2)), called h-symplecton, are introduced and their properties are investigated. It is shown that many properties of symplecton for Lie algebra sl(2) are extended to h-symplecton. The h-symplecton is also a basis of irreducible

P. J. Forrester

A connection is made between the random turns model of vicious walkers and random permutations indexed by their increasing subsequences. Consequently the scaled distribution of the maximum displacements in a particular asymmeteric version of the model can be determined to be the same as the scaled distribution of the eigenvalues at the soft edge of the GUE.

Fiorenzo Bastianelli, Roberto Zucchini

We use the AdS/CFT correspondence to calculate three point functions of chiral primary operators at large N in d=3, N=8 and d=6, N=(2,0) superconformal field theories. These theories are related to the infrared fixed points of world-volume descriptions of N coincident M2 and M5 branes, respectively. The computation can be generalized by employing a gravitati

Mohab Abou Zeid, Christopher M. Hull

We investigate the relation between supersymmetry and geometry for two dimensional sigma models with target spaces of arbitrary signature, and Lorentzian or Euclidean world-sheets. In particular, we consider twisted forms of the two-dimensional $(p,q)$ supersymmetry algebra. Superspace formulations of the $(p,q)$ heterotic sigma-models with twisted or untwis

Carl M. Bender, Kimball A. Milton, Van M. Savage

In recent papers it has been observed that non-Hermitian Hamiltonians, such as those describing $igϕ^3$ and $-gϕ^4$ field theories, still possess real positive spectra so long as the weaker condition of ${\cal PT}$ symmetry holds. This allows for the possibility of new kinds of quantum field theories that have strange and quite unexpected properties. In this

M. Bojowald, H. A. Kastrup

Utilizing the previously established general formalism for quantum symmetry reduction in the framework of loop quantum gravity the spectrum of the area operator acting on spherically symmetric states in 4 dimensional pure gravity is investigated. The analysis requires a careful treatment of partial gauge fixing in the classical symmetry reduction and of the

M. Bojowald, H. A. Kastrup

Given a symmetry group acting on a principal fibre bundle, symmetric states of the quantum theory of a diffeomorphism invariant theory of connections on this fibre bundle are defined. These symmetric states, equipped with a scalar product derived from the Ashtekar-Lewandowski measure for loop quantum gravity, form a Hilbert space of their own. Restriction to

Edward Witten

We use a D-instanton or physical gauge approach to re-derive the heterotic string worldsheet instanton contribution to the superpotential in Calabi-Yau compactification. We derive an analogous formula for worldsheet instanton corrections to the moduli space metric in heterotic string or Type I compactification on a K3 surface. In addition, we give a global a

G. Mussardo, S. Penati

We study an integrable quantum field theory of a single stable particle with an infinite number of resonance states. The exact $S$--matrix of the model is expressed in terms of Jacobian elliptic functions which encode the resonance poles inherently. In the limit $l \to 0$, with $l$ the modulus of the Jacobian elliptic function, it reduces to the Sinh--Gordon

J. Kluson

In the present paper we calculate the statistical partition function for any number of extended objects in Matrix theory in the one loop approximation. As an application, we calculate the statistical properties of K clusters of D0 branes and then the statistical properties of K membranes which are wound on a torus.

B. Kleihaus, D. H. Tchrakian, F. Zimmerschied

A systematic numerical study of the classical solutions to the combined system consisting of the Georgi-Glashow model and the SO(3) gauged Skyrme model is presented. The gauging of the Skyrme system permits a lower bound on the energy, so that the solutions of the composite system can be topologically stable. The solutions feature some very interesting bifur

R. J. Finkelstein

The straightforward description of q-deformed systems leads to transition amplitudes that are not numerically valued. To give physical meaning to these expressions without introducing {\it ad hoc} remedies, one may exploit an &#34;internal&#34; Fock space already defined by the q-algebra. This internal space may be interpreted in terms of internal degrees of

Jun-Chen Su, Lian-You Shan, Ying-Hui Cao

The QCD one-loop renormalization is restudied in a mass-dependent subtraction scheme in which the quark mass is not set to vanish and the renormalization point is chosen to be an arbitrary timelike momentum. The correctness of the subtraction is ensured by the Ward identities which are respected in all the processes of subtraction. By considering the mass ef

Jun-Chen Su, Xue-Xi Yi, Ying-Hui Cao

The QED renormalization is restudied by using a mass-dependent subtraction which is performed at a time-like renormalization point. The subtraction exactly respects necessary physical and mathematical requirements such as the gauge symmetry, the Lorentz- invariance and the mathematical convergence. Therefore, the renormalized results derived in the subtracti

D. Brian Walton, Johann Rafelski

We obtain within Fokker-Planck dynamics an explicit generalization of Einstein&#39;s relation between drag, diffusion and equilibrium distribution for a spatially homogeneous system, considering both the transverse and longitudinal diffusion for dimension n>1. We then provide a complete characterization of when the equilibrium distribution becomes a Boltzman

Carlos L. Schat, Norberto N. Scoccola

We investigate the possible existence of multibaryons with heavy flavor quantum numbers using the bound state approach to the topological soliton model and the recently proposed approximation for multiskyrmion fields based on rational maps. We use an effective interaction lagrangian which consistently incorporates both chiral symmetry and the heavy quark sym

I. I. Bigi

Heavy Quark Expansions for semileptonic decays of beauty hadrons are briefly reviewed. I analyze how $|V(cb)|$ can be extracted from the semileptonic width of $B$ mesons, the average semileptonic width of all weakly decaying beauty hadrons and from $B \ra l νD^*$ at zero recoil. Special attention is paid to present theoretical uncertainties (including correl

M. Anselmino, M. Boglione, F. Murgia

We present a phenomenological approach to the description of single transverse spin asymmetries (STSA) in inclusive hadron production. It generalizes the pQCD formalism for high energies and large p_T inclusive hadron production processes, A+B -> C+X, by incorporating quark intrinsic motion in the spin dependent quark distribution and fragmentation functions

R. Baier, Yu. L. Dokshitzer, A. H. Mueller, D. Schiff

The induced momentum spectrum of soft gluons radiated from a high energy quark propagating through a QCD medium is derived in the BDMPS formalism. A calorimetric measurement for the medium dependent energy lost by a jet with opening angle $θ_{\rm cone}$ is proposed.The fraction of this energy loss with respect to the integrated one appears to be the relevant

I. N. Erofeeva, V. S. Murzin, V. A. Nikonov, Yu. M. Shabelski

The experimental data on $K^0$ and $Λ$ production by $ν$ and $\barν$ beams are compared with the predictions of quark model assuming that the direct production of secondaries dominates. Disagreement of these predictions with the data allows one to suppose that there exists considerable resonance decay contribution to the multiplicities of produced secondarie

Gabriel Amoros, Johan Bijnens, Pere Talavera

The vector and axial-vector two-point functions are calculated to next-to-next-to-leading order in Chiral Perturbation Theory for three light flavours. We also obtain expressions at the same order for the masses, $m_π^2$, $m_K^2$ and $m_η^2$, and the decay constants, $F_π$, $F_K$ and $F_η$. We present some numerical results after a simple resonance estimate

Abhijit Bhattacharyya, Jan-e Alam, Sourav Sarkar, Pradip Roy

We calculate the size distribution of quark nuggets, which could be formed due to first order QCD phase transition in the early universe. We find that there are a large number of stable Quark Nuggets which could be a viable candidate for cosmological dark matter.

2 Collaboration

Radiative decays of the $ϕ$ meson have been studied using a data sample of about 19 million $ϕ$ decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. From selected $e^+e^-\toπ^{0}π^{0}γ$ and $e^+e^-\toηπ^{0}γ$ events the following model independent results have been obtained: \par $Br(ϕ\toπ^{0}π^{0}γ) = (0.92\pm 0.08\pm0.06)\times10^{-4}

2 Collaboration

Radiative decays of the $ϕ$ meson have been studied using a data sample of about 20 million $ϕ$ decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. From selected $e^+e^-\toπ^{+}π^{-}γ$ events the $ϕ\toπ^{+}π^{-}γ$ decay has been observed for the first time. \par Under the assumption that the intermediate $f_{0}(980)γ$ state dominates i

M. N. Achasov, V. M. Aulchenko, A. V. Berdyugin, A. V. Bozhenok

The search for CP-violating K_S\to3π^0 decay was performed with SND detector at VEPP-2M e^+e^- collider. The total amount of data corresponding to 7 million produced K_S mesons was analyzed. No candidate events were found, giving an upper limit of the decay branching ratio: Br(K_S\to3π^0) < 1.4\cdot10^{-5} at 90% confidence level.

A. G. Agnese, M. La Camera

We reconsider the Kerr metric with cosmological term $Λ$ imposing the condition that the angular velocity $ω$ of the dragging of the inertial frames vanishes at spatial boundaries. Some properties of the extreme black holes in the revisited solutions are discussed.

Francesc Fayos, Carlos F Sopuerta

In this paper we study the electromagnetic fields generated by a Killing vector field in vacuum space-times (Papapetrou fields). The motivation of this work is to provide new tools for the resolution of Maxwell&#39;s equations as well as for the search, characterization, and study of exact solutions of Einstein&#39;s equations. The first part of this paper i

Edward Malec

We describe general-relativistically a spherically symmetric stationary fluid accretion onto a black hole. Relativistic effects enhance mass accretion, in comparison to the Bondi model predictions, in the case when backreaction is neglected. That enhancement depends on the adiabatic index and the asymptotic gas temperature and it can magnify accretion by one

David Elworthy

A statistical classification algorithm and its application to language identification from noisy input are described. The main innovation is to compute confidence limits on the classification, so that the algorithm terminates when enough evidence to make a clear decision has been made, and so avoiding problems with categories that have similar characteristic

Atsushi Fujii, Tetsuya Ishikawa

This paper proposes a Japanese/English cross-language information retrieval (CLIR) system targeting technical documents. Our system first translates a given query containing technical terms into the target language, and then retrieves documents relevant to the translated query. The translation of technical terms is still problematic in that technical terms a

Eugene Demler, Eugene H. Kim, S. Das Sarma

Based on the construction of generalized Halperin wave functions, we predict the possible existence of a large class of broken spin symmetry states in bilayer quantum Hall structures, generalizing the recently suggested canted antiferromgnetic phase to many fractional fillings. We develop the appropriate Chern-Simons theory, and establish explicitly that the

J. Oppenlaender, Ch. Haeussler, N. Schopohl

We present a theoretical study on the dynamical properties of three-dimensional arrays of Josephson junctions. Our results indicate that such superconducting networks represent highly sensitive 3D-SQUIDs having some major advantages in comparison with conventional planar SQUIDs. The voltage response function of 3D-SQUIDs is directly related to the vector-cha

T. Jarlborg

The correlation holes for densities of equal and opposite spin around a test electron are determined from the Schrödinger equation with proper boundary conditions. The traditional &#34;exchange&#34; term follows from the boundary condition which respects a spacial exclusion principle for equal spins. The resulting potential compares reasonably well with stan

Franco Dalfovo, Michele Modugno

The expansion of Bose-Einstein condensates with quantized vortices is studied by solving numerically the time-dependent Gross-Pitaevskii equation at zero temperature. For a condensate initially trapped in a spherical harmonic potential, we confirm previous results obtained by means of variational methods showing that, after releasing the trap, the vortex cor

S. M. Fielding, P. Sollich, M. E. Cates

We study theoretically the role of ageing in the rheology of soft materials. We define several generalized rheological response functions suited to ageing samples (in which time translation invariance is lost). These are then used to study ageing effects within a simple scalar model (the &#34;soft glassy rheology&#34; or SGR model) whose constitutive equatio

V. B. Shenoy, R. V. Kukta, R. Phillips

We develop a finite element based dislocation dynamics model to simulate the structure and strength of dislocation junctions in FCC crystals. The model is based on anisotropic elasticity theory supplemented by the explicit inclusion of the separation of perfect dislocations into partial dislocations bounding a stacking fault. We demonstrate that the model re

F. V. Kusmartsev, H. S. Dhillon, M. D. Crapper

To characterize the possible magnetic structures created on magnetic multilayers a model has been formulated and studied. The interlayer inhomogeneous structures found indicate either (i) a regular periodic, (ii) a quasiperiodic change in the magnetization or (iii) spatially chaotic glass states. The magnetic structures created depend mainly on the ratio of

Y. Georgelin, T. Masson, J. -C. Wallet

We analyze various properties of the visibility diagrams that can be used in the context of modular symmetries and confront them to some recent experimental developments in the Quantum Hall Effect. We show that a suitable physical interpretation of the visibility diagrams which permits one to describe successfully the observed architecture of the Quantum Hal

J. D. Lee

The valence level photoemission spectra in the Anderson impurity model for Ce compounds at zero temperature are studied as a function of the photon energy $ω$. Most of former studies on Ce compounds are based on the sudden approximation, which is valid in high energy region. For the photoemission in the adiabatic limit of low energy region, one should consid

S. -K. Yip

We investigate the dependence of the current-phase relationship on the orientation of the order parameter for a pinhole between two $^3$He-B reservoirs. We show that, due to the internal spin structure of the superfluid, the energy of the junction may have a relative minimum at phase difference equals $π$ at low temperatures. The dependence of the supercurre

Egidijus Anisimovas, Peter Johansson

We calculate the energy band structure for electrons in an external periodic potential combined with a perpendicular magnetic field. Electron-electron interactions are included within a Hartree approximation. The calculated energy spectra display a considerable degree of self-similarity, just as the ``Hofstadter butterfly.&#39;&#39; However, screening affect

F. Bonetto, G. Gentile

At the light of recent results in literature we review a conjecture formulated in Math. Phys. Electron. J. 1 (1995), paper 5, 1--13, about the mechanism of breakdown of invariant sets in KAM problems and the identification of the dominant terms in the perturbative expansion of the conjugating function. We show that some arguments developed therein can be car

J. M. Shull, B. D. Savage, J. A. Morse, S. G. Neff

This is the report of the Ultraviolet-Optical Working Group (UVOWG) commissioned by NASA to study the scientific rationale for new missions in ultraviolet/optical space astronomy approximately ten years from now, when the Hubble Space Telescope (HST) is de-orbited. The UVOWG focused on a scientific theme, The Emergence of the Modern Universe, the period from

Tod R. Lauer

An undersampled point spread function may interact with the microstructure of a solid-state detector such that the total flux detected can depend sensitively on where the PSF center falls within a pixel. Such intra-pixel sensitivity variations will not be corrected by flat field calibration and may limit the accuracy of stellar photometry conducted with unde

N. Kameswara Rao, David L. Lambert, Mark T. Adams, David R. Doss

A set of high-resolution optical spectra of RCrB acquired before, during, and after its 1995-1996 decline is discussed. All of the components reported from earlier declines are seen. This novel dataset provides new information on these components including several aspects not previously seen in declines of RCrB and other RCBs. In the latter category is the d

M. A. Bransford, D. A. Thilker, R. A. M. Walterbos, N. L. King

We present the results of an ongoing investigation to provide a detailed view of the processes by which massive stars shape the surrounding interstellar medium (ISM), from pc to kpc scales. In this paper we have focused on studying the environments of Wolf-Rayet (WR) stars in M31 to find evidence for WR wind-ISM interactions, through imaging ionized hydrogen

D. Lynden-Bell, J. P. S. Lemos

The stability of self-similar power-law disks to non-axially symmetrical disturbances of zero frequency (omega = 0) is discussed. It is established that marginally unstable modes either have (omega = 0) or consist of continua with modes of all frequencies becoming unstable together. A careful study of all modes close to omega = 0 yields a remarkable conclusi

Stefanie Komossa, Dieter Breitschwerdt, Hans Boehringer, Janek Meerschweinchen

We present here an analysis of the X-ray properties of a sample of LINER galaxies observed with the ROSAT PSPC and HRI instruments. A spatial analysis shows that the bulk of the X-ray emission is consistent with arising from a point source; some extended emission appears at weak emission levels. The X-ray spectra are formally best described by a powerlaw wit

Chiaki Kobayashi, Nobuo Arimoto

We have re-studied line-strength gradients of 80 elliptical galaxies. Typical metallicity gradients are d[Fe/H]/dlogr = -0.3. The metallicity gradients do not correlate with any physical properties of galaxies, including central and mean metallicities, central velocity dispersions sigma0, absolute B-magnitudes MB, absolute effective radii Re, and dynamical m

Kulinder Pal Singh

An extended component of X-ray emission has been detected in Seyfert galaxies - NGC 1365 and NGC 4051, using the ROSAT HRI. Its size is about 2 kpc and it contains 56% +- 8% of the total observed flux in NGC 1365, and 21% +- 6% in NGC 4051. Extended emission in NGC 1365 is aligned with the inner disk structure, has wings along the east and west direction ali

R. Capuzzo-Dolcetta, R. Di Lisio

We study the problem of the appropriate choice of the interpolating kernel to be used in the evaluation of gradients of functions. Such interpolation technique is often used in applications, e.g. it is typical for Smoothed Particle Hydrodynamics (SPH). We propose a minimization procedure for selecting kernels in n-dimensions, in the class of regular, normali

Monica Colpi, Lucio Mayer, Fabio Governato

The evolution of a small satellite inside a more massive truncated isothermal spherical halo is studied using both the Theory of Linear Response for dynamical friction and N-Body simulations. The analytical approach includes the effects of the gravitational wake, of the tidal deformation and the shift of the barycenter of the primary, so unifying the local v

D. V. Bisikalo, A. A. Boyarchuk, O. A. Kuznetsov, V. M. Chechetkin

Results of 3D gas dynamical simulation of mass transfer in binaries are presented for systems with various values of viscosity. Analysis of obtained solutions shows that in the systems with low value of viscosity the flow structure is qualitatively similar to one for systems with high viscosity. Presented calculations confirm that there is no shock interacti

Leo Girardi

Some fine structures can nowadays be identified in the high-quality colour-magnitude diagrams (CMD) of Local Group galaxies. The clump of red giants, for instance, may present a significant colour spread, and extensions to both brighter and fainter luminosities. Such features are predicted by population synthesis models which consider stars in the complete r

Shardha Jogee, Jeffrey D. P. Kenney, Beverly J. Smith

We present evidence that the peculiar interacting starburst galaxy NGC 2782 (Arp 215) harbors a gas-rich nuclear stellar bar feeding an M82-class powerful central starburst, from a study based on OVRO CO (J=1->0) data, WIYN BVR & Halpha observations, along with available NIR images, a 5 GHz RC map and HST images. NGC 2782 harbors a clumpy, bar-like CO featur

D. V. Bisikalo, A. A. Boyarchuk, V. M. Chechetkin, O. A. Kuznetsov

We present the results of systematic comparison of 2D and 3D numerical models of mass transfer in semidetached binaries. It is shown that only for case of γ\sim 1 (near-isothermal case) the obtained 2D and 3D solutions are qualitatively similar. For higher value of γthe 3D flow structure is drastically changed and for γ=1.2 the accretion disk is not formed i

Y. I. Izotov, P. Papaderos, T. X. Thuan, K. J. Fricke

Hubble Space Telescope (HST) colour - magnitude diagrams in B, V and R along with long-slit Multiple Mirror Telescope (MMT) spectrophotometric data are used to investigate the evolutionary status of the nearby blue compact dwarf (BCD) galaxy I Zw 18. We find that the distance to I Zw 18 should be as high as 20 Mpc, twice the previously accepted distance, to

Andrew Gould, Samir Salim

By combining SIM observations with ground-based photometry, one can completely solve microlensing events seen toward the Galactic bulge. One could measure the mass, distance, and transverse velocity of ~100 lenses to ~5% precision in only ~500 hours of SIM time. Among the numerous applications are 1) measurement of the mass functions (MFs) of the bulge and d

J. Hwang

We introduce a scalar-type perturbation variable $Φ$ which is conserved in the large-scale limit considering general sign of three-space curvature ($K$), the cosmological constant ($Λ$), and time varying equation of state. In a pressureless medium $Φ$ is {\it exactly conserved} in all scales.

Esther M. Hu, Richard G. McMahon, Lennox L. Cowie

We report the discovery of an extremely luminous galaxy lying at a redshift of z=5.74, SSA22-HCM1. The object was found in narrowband imaging of the SSA22 field using a 105 Angstrom bandpass filter centered at 8185 Angstroms during the course of the Hawaii narrowband survey using LRIS on the 10 m Keck II Telescope, and was identified by the equivalent width

Merced Montesinos, Abdel Pérez-Lorenzana

We find a relationship between unitary transformations of the dynamics of quantum systems with time-dependent Hamiltonians and gauge theories. In particular, we show that the nonrelativistic dynamics of spin-$\frac12$ particles in a magnetic field $B^i (t)$ can be formulated in a natural way as an SU(2) gauge theory, with the magnetic field $B^i(t)$ playing

Arun K. Pati

We show that a qubit chosen from equatorial or polar great circles on a Bloch spehere can be remotely prepared with one cbit from Alice to Bob if they share one ebit of entanglement. Also we show that any single particle measurement on an arbitrary qubit can be remotely simulated with one ebit of shared entanglement and communication of one cbit.

L. G. Cabral-Rosetti, J. Bernabeu, J. Vidal, A. Zepeda

We present a computation of the charge and the magnetic moment of the neutrino in the recently developed electro-weak Background Field Method and in the linear $R_ξ^L$ gauge. First, we deduce a formal Ward-Takahashi identity which implies the immediate cancellation of the neutrino electric charge. This Ward-Takahashi identity is as simple as that for QED. Th

Stephan Mertens

The random cost problem is the problem of finding the minimum in an exponentially long list of random numbers. By definition, this problem cannot be solved faster than by exhaustive search. It is shown that a classical NP-hard optimization problem, number partitioning, is essentially equivalent to the random cost problem. This explains the bad performance of

Fuqiang Wang, Scott Pratt

The prospect of using lambda-proton correlations to extract source sizes in relativistic heavy ion collisions is investigated. It is found that the strong interaction induces a large peak in the correlation function that provides more sensitive source size measurements than two-proton correlations under some circumstances. The prospect of using lambda-proton

J. Eisert, T. Felbinger, P. Papadopoulos, M. B. Plenio

We establish a quantitative connection between the amount of lost classical information about a quantum state and the concomitant loss of entanglement. Using methods that have been developed for the optimal purification of mixed states we find a class of mixed states with known distillable entanglement. These results can be used to determine the quantum capa

I. Jack, D. R. T. Jones

We show that the results for the soft couplings in supersymmetric gauge theories recently derived via the superconformal anomaly are equivalent to results obtained earlier from a consideration of exact RG-invariant trajectories. We give a full proof of these results for a general multi-coupling theory. Moreover, we demonstrate the existence of a distinct fin

Marc Toussaint

We will discuss some analogies between internal gauge theories and gravity in order to better understand the charge concept in gravity. A dimensional analysis of gauge theories in general and a strict definition of elementary, monopole, and topological charges are applied to electromagnetism and to teleparallelism, a gauge theoretical formulation of Einstein

Paolo Gambino, Pietro Antonio Grassi

In a generic gauge theory the gauge parameter dependence of individual Green functions is controlled by the Nielsen identities, which originate from an enlarged BRST symmetry. We give a practical introduction to the Nielsen identities of the Standard Model (SM) and to their renormalization and illustrate the power of this elegant formalism in the case of the

Yu. V. Tarasov

The method is proposed adapted for calculating the T=0 conductance of arbitrarily stretched disordered conducting strips in terms of the Kubo theory. The 2D scattering problem is solved through exact one-dimensionalization in mode representation (instead of quasiclassical) that enables to allow reasonably for quantum interference of scattered waves as well a

Pablo M. Gleiser, Francisco A. Tamarit, Sergio A. Cannas

In this work we study the effects of introducing long range interactions in the Bak-Sneppen (BS) model of biological evolution. We analyze a recebtly propopsed version of the BS model where the interactions decay as r^{-alpha}; in this way the first nearest neighbors model is recovered in the limit alpha -> infinity, and the random neighbors version for alph