November 1999 arXiv papers — page 11

Hideo Iguchi, Tomohiro Harada, Ken-ichi Nakao

A naked singularity occurs in the generic collapse of an inhomogeneous dust ball. We study the even-parity mode of gravitational waves from a naked singularity of the Lema\^ıtre-Tolman-Bondi spacetime. The wave equations for gravitational waves are solved by numerical integration using the single null coordinate. The result implies that the metric perturbati

Jeffrey P. Gardner, Neal Katz, Lars Hernquist, David H. Weinberg

We use hydrodynamic cosmological simulations to study damped Lyman-alpha (DLA) and Lyman limit (LL) absorption at redshifts z=2-4 in five variants of the cold dark matter scenario. Our standard simulations resolve the formation of dense concentrations of neutral gas in halos with circular velocity v_c roughly 140 km/s for Omega_m=1 and 90 km/s for Omega_m=0.

Ashish Ahuja, Sanjiv Kapoor

This paper describes a quantum algorithm for finding the maximum among N items. The classical method for the same problem takes O(N) steps because we need to compare two numbers in one step. This algorithm takes O(sqrt(N)) steps by exploiting the property of quantum states to exist in a superposition of states and hence performing an operation on a number of

M. N. Sergeenko

The properties of relativistic particles in the quasiclassical region are investigated. The relativistic semiclassical wave equation appropriate in the quasiclassical region is derived. It is shown that the leading-order WKB quantization rule is the appropriate method to solve the equation obtained.

G. Gilat

The presence of chirality in the main molecules of life may well be not just a structural artifact, but of pure biological advantage. The possibility of the existence of a phenomenon of a special mode of interaction, labeled as "chiral interaction" (CI), for which structural chirality is a necessary condition, is the main reason for such an advantage

Louis H. Kauffman

This paper gives a summary of our approach to invariants of three manifolds via right integrals on finite dimensional Hopf algebras and their relation to the Kirby calculus.

Cameron McA. Gordon

We give a summary of known results on the maximal distances between Dehn fillings on a hyperbolic 3-manifold that yield 3-manifolds containing a surface of non-negative Euler characteristic that is either essential or Heegaard.

G. Corach, A. Maestripieri, D. Stojanoff

Let A be a unital C* algebra with involution * represented in a Hilbert space H, G the group of invertible elements of A, U the unitary group of A, G^s the set of invertible selfadjoint elements of A, Q={e in G : e^2 = 1} the space of reflections and P = Q\cap U. For any positive a in G consider the a-unitary group U_a={g in G : a^{-1} g^* a = g^{-1}}, i.e.

N. J. Kalton

Johnson and Zippin recently showed that if $X$ is a weak^*-closed subspace of $\ell_1$ and T:X-> C(K) is any bounded operator then T can extended to a bounded operator $\tilde T:\ell_1\to C(K).$ We give a converse result: if X is a subspace of $\ell_1$ so that $\ell_1/X$ has a (UFDD) and every operator T:X -> C(K) can be extended to $\ell_1$ then there is an

Inhyeop Yi

We define canonical subshift of finite type cover for Williams' 1-dimensional generalized solenoids, and use resulting invariants to distinguish some closely related solenoids.

E. Andruchow, G. Corach, D. Stojanoff

Based on the projective matrix spaces studied by B. Schwarz and A. Zaks, we study the notion of projective space associated to a C*-algebra A with a fixed projection p. The resulting space P(p) admits a rich geometrical structure as a holomorphic manifold and a homogeneous reductive space of the invertible group of A. Moreover, several metrics (chordal, sphe

D. Gurevich, Z. Mriss

To a vector space V equipped with a non-quasiclassical involutary solution of the quantum Yang-Baxter equation and a partition $λ$, we associate a vector space $\Vl$ and compute its dimension. The functor $V\mapsto \Vl$ is an analogue of the well-known Schur functor. The category generated by the objects $\Vl$ is called the Schur-Weyl category. We suggest a

Francisco J. Herranz

By starting from the non-standard quantum deformation of the sl(2,R) algebra, a new quantum deformation for the real Lie algebra so(2,2) is constructed by imposing the former to be a Hopf subalgebra of the latter. The quantum so(2,2) algebra so obtained is realized as a quantum conformal algebra of the (1+1) Minkowskian spacetime. This Hopf algebra is shown

Martin Barlow, Krzysztof Burdzy, Haya Kaspi, Avi Mandelbaum

We prove that two skew Brownian motions with the same skewness parameter (different from 0) and driven by the same Brownian motion coalesce a.s.

Marcelo Laca

When S is a discrete subsemigroup of a discrete group G such that G = S^{-1} S, it is possible to extend circle-valued multipliers from S to G; to dilate (projective) isometric representations of S to (projective) unitary representations of G; and to dilate/extend actions of S by injective endomorphisms of a C*-algebra to actions of G by automorphisms of a l

Marcelo Laca, Iain Raeburn

We compute explicitly the primitive ideal space of the Bost-Connes Hecke C*-algebra by embedding it as a full corner in a transformation group C*-algebra and applying a general theorem of Williams. This requires the computation of the quasi-orbit space for the action of the multiplicative positive rationals on the space of finite adeles. We then carry out a

E. Andruchow, G. Corach, D. Stojanoff

Let A be a unital C*-algebra. Denote by P the space of selfadjoint projections of A. We study the relationship between P and the spaces of projections P_a determined by the different involutions #_a induced by positive invertible elements a in A. The maps f_p: P \to P_a sending p to the unique q in P_a with the same range as p and Ω_a: P_a \to P sending q to

Joel Hass, Peter Scott

We study configurations of immersed curves in surfaces and surfaces in 3-manifolds. Among other results, we show that primitive curves have only finitely many configurations which minimize the number of double points. We give examples of minimal configurations not realized by geodesics in any hyperbolic metric.

I. Ya. Aref'eva, A. S. Koshelev, P. B. Medvedev

We study the spectrum of SU(2) x SO(2) matrix supersymmetric quantum mechanics. We use angular coordinates that allow us to find an explicit solution of the Gauss law constraints and single out the quantum number n (the Lorentz angular momentum). Energy levels are four-fold degenerate with respect to n and are labeled by n_q, the largest n in a quartet. The

Ofer Aharony

This is a brief review of the current state of knowledge on "little string theories", which are non-gravitational theories having several string-like properties. We focus on the six dimensional maximally supersymmetric "little string theories" and describe their definition, some of their simple properties, the motivations for studying them, t

H. Reinhardt, M. Engelhardt, K. Langfeld, M. Quandt

The vortex picture of confinement is studied. The deconfinement phase transition is explained as a transition from a phase in which vortices percolate to a phase of small vortices. Lattice results are presented in support of this scenario. Furthermore the topological properties of magnetic monopoles and center vortices arising, respectively, in Abelian and c

C. Bizdadea, S. O. Saliu, E. N. Tîmneanu

Spin-5/2 gauge fields are quantized in an irreducible way within both the BRST and BRST-anti-BRST manners. To this end, we transform the reducible generating set into an irreducible one, such that the physical observables corresponding to these two formulations coincide. The gauge-fixing procedure emphasizes on the one hand the differences among our procedur

C. Bizdadea, S. O. Saliu

p-form gauge theories with Stueckelberg coupling are quantized in an irreducible antifield-BRST way. As a consequence, neither the ghosts of ghosts nor their antifields appear. Some irreducible gauge conditions are inferred naturally within our formalism. In the end we briefly discuss the interacting case.

C. Bizdadea, S. O. Saliu

The irreducible antifield formalism for $p$-form gauge theories with gauge invariant interaction terms is exposed. The ghosts of ghosts do not appear. The acyclicity of the Koszul-Tate operator is ensured without introducing antifields at resolution degrees higher that two.

S. R. Das, S. Kalyana Rama, S. P. Trivedi

We study Type IIB supergravity in the presence of (euclidean) D3 branes and nonzero self-dual B-fields. We point out that the Einstein frame metric is identical to the full geometry for D3 branes without B fields turned on. Furthermore, in a decoupling limit in which the theory is conjectured to be dual to noncommutative Yang-Mills theory, the entire Einstei

Carlos Castro

It is shown that a Moyal deformation quantization of the SO(4k) Generalized Yang-Mills (GYM) theory action in D=4k dimensions, for spacetime independent field configurations, in the $\hbar \to 0$ limit, yields the Dirac-Nambu-Goto p-brane actions (obtained from the conformally invariant Dolan-Tchrakian p-brane actions after elimination of the auxiliary world

Norberto N. Scoccola

We report on the result of some investigations concerning the radiative decays of decuplet baryons and the non-leptonic weak decays of the octet baryons in the context of topological chiral soliton models. Our results are compared with those of alternative baryon models. For the radiative decays we find that the predictions are similar to those of quark mode

Norberto N. Scoccola

Low-lying multibaryon configurations are studied within the bound state approach to the SU(3) Skyrme model. We use approximate ansaetze for the static background fields based on rational maps which have the same symmetries of the exact solutions. To determine the explicit form of the collective Hamiltonians and wave functions we only make use of these symmet

Laura Covi

We study models of inflation where the inflaton corresponds to a flat direction in field space and its mass term is generated by gravity mediated soft supersymmetry breaking at high scale. Assuming the inflaton to have non negligible couplings to other fields, its mass runs with scale and can reach the small value required by slow roll inflation at a lower s

F. del Aguila

The top flavour-changing neutral couplings can be large in extended models with vector-like quarks. In the next decade(s) the CERN Large Hadron Collider will allow to measure (bound) them with a precision of few per cent.

M. G. Mustafa, A. Schaefer, M. H. Thoma

We evaluate the quark-photon vertex non-perturbatively taking into account the gluon condensate at finite temperature. This vertex is related to the previously derived effective quark propagator by a QED like Ward-Takahashi identity. The importance of the effective vertex for the dilepton production rate from a quark-gluon plasma is stressed.

Kh. M. Beshtoev

In the framework of the Standard Model the probability (and time) of pi --> K transitions (oscillations) are computed. These transitions are virtual ones since masses of pi and K mesons differ considerably. These transitions (oscillations) can be registered through K decays after transitions of virtual K mesons to their own mass shell by using their quasiela

Yu Zeng-Hui, Herbert. Pietschmann, Ma Wen-Gan, Han Liang

We studied the process $e^{+}e^{-} \to t\bar{c}+c\bar{t}$ in a R_{p} violating supersymmetric model with effects from both B- and L-violating interactions. The calculation shows that it is possible to either detect the R_{p} violating signal at the Next Linear Collider or get more stringent constraints on the heavy-flavor $\rlap/R_{p}$ couplings. A comparisi

H. Neuberger

The overlap formulation of regulated vectorial and chiral gauge theories is reviewed. Ostensibly new constructions, based on the Ginsparg-Wilson relation are essentially just overlap with new notation. At present there exists no satisfactory realization of chiral symmetries outside perturbation theory which is structurally different from the overlap.

F. Vannucci

Little is known on radiative decays of numu and nutau. Lifetimes can be constrained, or the process discovered, by a search for flavour conversion in a superconducting RF cavity installed in a neutrino beam. The lifetimes tested with such a method can be of interest for astrophysics and cosmology. In particular the conjecture which explains both the LSND and

J. A. Aguilar-Saavedra

We present an algorithm which allows a fast numerical computation of Feldman-Cousins confidence intervals for Poisson processes, even when the number of background events is relatively large. This algorithm incorporates an appropriate treatment of the singularities that arise as a consequence of the discreteness of the variable.

Miroslav Sukenik, Jozef Sima

The model of Expansive Nondecelerative Universe exploiting the Vaidya metrics is used as a tool for unification of gravitation and strong interactions. The proposed approach stems from the capability to localize the energy of gravitational field and enables to reach a certain level in unifying the general theory of relativity and quantum chromodynamics. A re

James E. Lidsey

It is shown that any anisotropic and inhomogeneous cosmological solution to the lowest-order, four-dimensional, dilaton-graviton string equations of motion may be employed as a seed to derive a curved, three-brane cosmological solution to five-dimensional heterotic M-theory compactified on a Calabi-Yau three-fold. This correspondence formally relates a weakl

D. V. Fursaev

The basic assumption of the induced gravity approach is that Einstein theory is an effective, low energy-form of a quantum theory of constituents. In this approach the Bekenstein-Hawking entropy S^{BH} of a black hole can be interpreted as a measure of the loss of information about constituents inside the black hole horizon. To be more exact, S^{BH} is deter

Yasunori Fujii

We discuss some of the issues which we encounter when we try to invoke the scalar-tensor theories of gravitation as a theoretical basis of quintessence. One of the advantages of appealing to these theories is that they allow us to implement the scenario of a ``decaying cosmological constant,'' which offers a reasonable understanding of why the observ

Masanori Ichioka, Kazushige Machida

Focusing on La_{2-x}Sr_{x}CuO_{4}, we study the stripe structure by the self-consistent mean-field theory of the Hubbard model. By introducing the realistic Fermi surface topology, the SDW-gapped insulator is changed to metallic. The solitonic features of the stripe structure and the contribution of the mid-gap states are presented. We consider the band disp

J. S. Dodge, A. B. Schumacher, D. S. Chemla, N. Ingle

We have created a nonequilibrium population of antiferromagnetic spin-waves in Cr2O3, and characterized its dynamics, using frequency- and time-resolved nonlinear optical spectroscopy of the exciton-magnon transition. We observe a time-dependent pump-probe line shape, which results from excitation induced renormalization of the spin-wave band structure. We p

V. Petkov, I-K. Jeong, F. Mohiuddin-Jacobs, Th. Proffen

High resolution total and indium differential atomic pair distribution functions (PDFs) for In_(0.5)Ga_(0.5)As alloys have been obtained by high energy and anomalous x-ray diffraction experiments, respectively. The first peak in the total PDF is resolved as a doublet due to the presence of two distinct bond lengths, In-As and Ga-As. The In differential PDF,

R. J. Radwanski

The understanding of magnetic and electronic properties of rare-earth intermetallics is summarized. The properties of NdNi5 or ErNi5 are understood by considering a few electronic subsystems like the f electronic subsystem and the conduction-electron subsystem. The localized f electrons can give a substantial contribution to the low temperature specific heat

S. Daul, D. J. Scalapino, Steven R. White

Antiferromagnetic and d_{x2-y2}-pairing correlations appear delicately balanced in the 2D Hubbard model. Whether doping can tip the balance to pairing is unclear and models with additional interaction terms have been studied. In one of these, the square of a local hopping kinetic energy H_W was found to favor pairing. However, such a term can be separated in

G. M. Maksimova, D. Yu. Vodolazov, I. L. Maksimov

The magnetic characteristics for superconducting samples of different geometries (plates and films of various widths) and orientation with respect to external field are compared. A similarity is established between the magnetization curves M(H) and the corresponding susceptibilities. A sign reversal is predicted for the 3rd harmonic of the ac susceptibillity

O. A. Starykh, D. L. Maslov, W. Häusler, L. I. Glazman

We investigate possible nontrivial phases of a two-subband quantum wire. It is found that inter- and intra-subband interactions may drive the electron system of the wire into a gapped state. If the nominal electron densities in the two subbands are sufficiently close to each other, then the leading instability is the inter-subband charge-density wave (CDW).

Trinh Xuan Hoang, Nazar Sushko, Mai Suan Li, Marek Cieplak

Reaching a ground state of a spin system is analogous to a protein evolving into its native state. We study the ``folding'' times for various random Ising spin systems and determine characteristic temperatures that relate to the ``folding''. Under optimal kinetic conditions, the ``folding'' times scale with the system size as a power

J. Kolacek, P. Lipavsky, V. Spicka

Generally it is accepted that electric field E in type II superconductors is created by the vortex motion, so that it is proportional to the vortex velocity v_L. This assertion is based on the Josephson relation E = - v_L x B, which was derived and is valid if no transport current is present. We present arguments showing that if transport current is present,

J. Kolacek, R. Tesar, Z. Simsa

Measurements of the far infrared magnetotransmission of YBa2(ZnxCu(1-x))3O(7-d) thin film (x = 0.025) deposited on a wedged MgO substrate are reported. The application of magnetic field perpendicular to the ab plane produces at low temperature a linear increase of transmission for frequencies below 30 cm-1. We present a model of high frequency vortex dynamic

S. A. Morgan

In this paper we develop a gapless theory of BEC which can be applied to both trapped and homogeneous gases at zero and finite temperature. The many-body Hamiltonian for the system is written in a form which is approximately quadratic with higher order cubic and quartic terms. The quadratic part is diagonalized exactly by transforming to a quasiparticle basi

M. Antoni, R. Cafiero

A two parameter model for single lane car-following is introduced and its equilibrium and non-equilibrium properties are studied. Despite its simplicity, this model exhibits a rich phenomenology, analogous to that observed in real traffic, like transitions between different dynamical regimes and hysteresis in the fundamental flux-density diagram. We show tha

Yves Elskens

A hierarchy of equations was introduced recently to describe the kinetics of homogeneous cooling of the gas of inelastic hard spheres. It is argued that this hierarchy does not describe this system accurately, and a simple test for this is proposed. A stochastic interpretation of the hierarchy is presented.

L. J. Lewis, P. Jensen, N. Combe, J-L. Barrat

We present a detailed molecular-dynamics study of the diffusion and coalescence of large (249-atom) gold clusters on graphite surfaces. The diffusivity of monoclusters is found to be comparable to that for single adatoms. Likewise, and even more important, cluster dimers are also found to diffuse at a rate which is comparable to that for adatoms and monoclus

G. Giacomelli, R. Hegger, A. Politi, M. Vassalli

We conjecture that in one-dimensional spatially extended systems the propagation velocity of correlations coincides with a zero of the convective Lyapunov spectrum. This conjecture is successfully tested in three different contexts: (i) a Hamiltonian system (a Fermi-Pasta-Ulam chain of oscillators); (ii) a general model for spatio-temporal chaos (the complex

J. Nevalainen, M. Markevitch, W. R. Forman

We calibrate the galaxy cluster mass - temperature relation using the temperature profiles of intracluster gas observed with ASCA (for hot clusters) and ROSAT (for cool groups). Our sample consists of apparently relaxed clusters for which the total masses are derived assuming hydrostatic equilibrium. The sample provides data on cluster X-ray emission-weighte

Barney Rickett, Bill Coles, Jussi Markkanen

Weak interstellar scintillations of pulsar B0809+74 were observed at two epochs using a 30m EISCAT antenna at 933 MHz. These have been used to constrain the spectrum, the distribution and the transverse velocity of the scattering plasma with respect to the local standard of rest (LSR). The Kolmogorov power law is a satisfactory model for the electron density

Mark L. Houdashelt, Roger A. Bell, Allen V. Sweigart

We present new grids of colors and bolometric corrections for F-K stars having 4000 K < Teff < 6500 K, 0.0 < log g < 4.5 and -3.0 < [Fe/H] < 0.0. A companion paper extends these calculations into the M giant regime. Colors are tabulated for Johnson U-V and B-V; Cousins V-R and V-I; Johnson-Glass V-K, J-K and H-K; and CIT/CTIO V-K, J-K, H-K and CO. We have de

Hendrik Lambert, Barney Rickett

We develop the theory of interstellar scintillation as caused by an irregular plasma having a power-law spatial density spectrum with a spectral exponent of 4 corresponding to a medium with abrupt changes in its density. An ``outer scale&#39;&#39; is included in the model representing the typical scale over which the density of the medium remains uniform. Su

Eric R. Tittley, H. M. P. Couchman

The significance of hierarchical clustering on the density profile and mass-temperature scaling relation for galaxy clusters is examined using hydrodynamic N-body simulations. Clusters formed hierarchically are compared with clusters formed with the initial density fluctuations on sub-cluster scales removed via smoothing. The universal profile, as described

Vahe Petrosian

Observational aspects of solar flares relevant to the acceleration process of electrons and protons are reviewed and it is shown that most of these observations can be explained by the interaction with flare plasma of a power law energy distribution of electrons (and protons) that are injected at the top of a flaring loop, in the so-called thick target model

Yu. A. Fadeyev, D. Gillet

Models of steady-state plane-parallel shock waves propagating through the unperturbed hydrogen gas of temperature T=6000K and density rho = 1e-10 gm/cm^3 are computed for upstream velocities from 15 km/s to 70 km/s. The shock wave structure is considered in terms of the self-consistent solution of the radiation transfer, fluid dynamics and rate equations for

Chip Kobulnicky, Karl Gebhardt

The [O II] lambda3727 emission lines and absorption features from stellar Balmer and Ca H&K lines are the most accessible kinematic diagnotics in galaxies at z~1. We investigate the kinematics of 22 local late-type galaxies using these spectral features and we compare the results to 21-cm neutral hydrogen spectra in order to assess the utility of each diagno

Frederic A. Rasio

Particle methods play an important role in the study of a wide variety of astrophysical fluid dynamics problems. The different methods currently in use are all variants of the so-called Smoothed Particle Hydrodynamics (SPH) scheme introduced by Lucy and Gingold & Monaghan more than twenty years ago. This paper presents a complete introduction to SPH in its m

Kate Scholberg

World-wide, several detectors currently running or nearing completion are sensitive to a prompt core collapse supernova neutrino signal in the Galaxy. The SNEWS system will be able to provide a robust early warning of a supernova&#39;s occurrence to the astronomical community using a coincidence of neutrino signals around the world. This talk describes the n

Rosemary F. G. Wyse

I discuss various proposed formation scenarios for the metal-poor components of the Milky Way Galaxy, emphasising the stellar halo and the thick disk. Interactions and accretion played a significant role in Galactic evolution, in particular at earlier epochs. The present observations favour a scenario by which the thick disk formed through the heating of a p

Rosemary F. G. Wyse, Gerard Gilmore, Sofia Feltzing, Mark Houdashelt

Low-mass stars, those with main-sequence lifetimes that are of order the age of the Universe, provide unique constraints on the Initial Mass Function (IMF) when they formed. Star counts in systems with simple star-formation histories are particularly straightforward to interpret, and those in old systems allow one to determine the low-mass stellar IMF at lar

S. C. Chapman, N. W. Watkins, G. Rowlands

Recently, the paradigm that the dynamic magnetosphere displays sandpile-type phenomenology has been advanced, in which energy dissipation is by means of avalanches which do not have an intrinsic scale. This may in turn imply that the system is in a self organised critical (SOC) state. Indicators of internal processes are consistent with this, examples are th

G. Lagache, L. M. Haffner, R. J. Reynolds, S. L. Tufte

We have used the WHAM H_alpha survey and Leiden/Dwingeloo HI data to decompose the Far-infrared emission (from 100 to 1000 micron) at high Galactic latitude into components associated with the Warm Ionised Medium (WIM) and the Warm Neutral Medium (WNM). This decomposition is possible for the first time thanks to preliminary WHAM data that cover a significant

M. Franx, P. G. van Dokkum, D. G. Fabricant, D. Kelson

We used the Hubble Space Telescope to take a wide field, multicolor image of the high redshift cluster MS1054-03 at z=0.83. The Keck telescope was used to take 200 redshifts in the field. We have a total of 81 spectroscopically confirmed cluster members with deep WFPC2 imaging. A surprisingly large number of these cluster members are mergers: 13 out of 77 ga

S. Covino, G. Tagliaferri, R. Pallavicini, R. Mewe

IIPeg is an ideal target to study stellar activity and flares, since intense and long lasting flares have been frequently detected from this system at all wavelengths. We report here about a BeppoSAX observation of IIPeg. We followed the system for ~19 hours on December 5 and 6 1997 with BeppoSAX and the X-ray light curve resembles the typical behavior of a

W. K. Huchtmeier, I. D. Karachentsev, V. E. Karachentseva, M. Ehle

We present HI observations of the galaxies in the first list of the Karachentsev catalog of previously unknown nearby dwarf galaxies (Karachentseva & Karachentsev 1998). This survey covers all known nearby galaxy groups within the Local Volume (i.e. within 10 Mpc) and their environment, that is about 25% of the total sky. A total of 257 galaxies have been ob

D. Blaschke, D. M. Sedrakian, K. M. Shahabasyan

Within recent nonperturbative approaches to the effective quark interaction the diquark condensate forms a superconductor of second kind. Therefore the magnetic field will not be expelled from the superconducting quark core in accordance with observational data which indicate that life times of pulsar magnetic fields exceed 10^7 years.

J. B. Hearnshaw, I. A. Bond, N. J. Rattenbury, S. Noda

A review of the MOA (Microlensing Observations in Astrophysics) project is presented. MOA is a collaboration of approximately 30 astronomers from New Zealand and Japan established with the aim of finding and detecting microlensing events towards the Magellanic Clouds and the Galactic bulge, which may be indicative of either dark matter or of planetary compan

Xiang-Ping Wu, Yan-Jie Xue

Numerical simulations of structure formation have suggested that there exists a good correlation between the halo concentration c (or the characteristic density delta_c) and the virial mass Mvir for any virialized dark halo described by the Navarro, Frenk & White (1995) density profile. In this Letter, we present an observational determination of the c-Mvir

Sergey P. Trudolyubov, Konstantin N. Borozdin, William C. Priedhorsky

We present an analysis of the RXTE observations of 4U 1630-47 during its outburst of 1998. The light curve and the spectral evolution of the outburst were distinctly different from the outbursts of the same source in 1996 and in 1999. Special emphasis of our analysis was on the observations taken during the initial rise of the flux and during the maximum of

E. V. Gotthelf, G. Vasisht

We propose a simple explanation for the apparent dearth of radio pulsars associated with young supernova remnants (SNRs). Recent X-ray observations of young remnants have revealed slowly rotating (P ~ 10-s) central pulsars with pulsed emission above 2 keV, lacking in detectable radio emission. Some of these objects apparently have enormous magnetic fields, e

Alan Stockton

We describe the current status of two complementary programs to search for objects with strong emission lines in a ~300 A gap, centered at 9150 A, in the strong airglow emission. Both programs are being carried out with LRIS on the Keck II telescope. The first of these uses broad-band and narrow-band filter photometry to select candidates, followed by multi-

N. J. Curro, P. C. Hammel, B. J. Suh, M. Hücker

We report Cu and La nuclear magnetic resonance (NMR) measurements in the title compound that reveal an inhomogeneous glassy behavior of the spin dynamics. A low temperature peak in the La spin lattice relaxation rate and the ``wipeout&#39;&#39; of Cu intensity both arise from these slow electronic spin fluctuations that reveal a distribution of activation en

B. J. Suh, P. C. Hammel, M. Hücker, B. Büchner

We present La and Cu NMR relaxation measurements in single crystal La_{1.67}Eu_{0.2}Sr_{0.13}CuO_4. A strong peak in the La spin-lattice relaxation rate observed in the spin ordered state is well-described by the BPP mechanism[1] and arises from continuous slowing of electronic spin fluctuations with decreasing temperature; these spin fluctuations exhibit XY

S. D. Dalosto, J. Riera

A model of coupled antiferromagnetic spin-1/2 Heisenberg ladders is studied with numerical techniques. In the case of ferromagnetic interladder coupling we find that the dynamic and static structure factor has a peak at $(π,π/2)$ where the first (second) direction is along (transversal) to the ladders. Besides, we suggest that the intensity of this peak and

S. Deser

I present, in any D$\geq$4, closed-form type B conformal anomaly effective actions incorporating the logarithmic scaling cutoff dependence that generates these anomalies. Their construction is based on a novel class of Weyl-invariant tensor operators. The only known type A actions in D$\geq$4 are extensions of the Polyakov integral in D=2; despite contrary a

Neil R. Constable, Robert C. Myers, Oyvind Tafjord

We examine noncommutative solutions of the nonabelian theory on the world-volume of N coincident D-strings. These solutions can be interpreted in terms of noncommutative geometry as funnels describing the nonabelian D-string expanding out into an orthogonal D3-brane. These configurations are `dual&#39; to the bion solutions in the abelian world-volume theory

Andri M. Gretarsson, Gregory M. Harry, Steven D. Penn, Peter R. Saulson

We report on the mechanical loss in fused silica samples with various surface treatments and compare them with samples having an optical coating. Mild surface treatments such as washing in detergent or acetone were not found to affect the mechanical loss of flame-drawn fused silica fibers stored in air. However, mechanical contact (with steel calipers) signi

S. Groote, J. G. Körner, A. A. Pivovarov

We present analytical next-to-leading order results for the correlator of baryonic currents at the three loop level with one finite mass quark. We obtain the massless and the HQET limit of the correlator from the general formula as particular cases. We also give explicit expressions for the moments of the spectral density.

Xuedong Hu, S. Das Sarma

We study theoretically a double quantum dot hydrogen molecule in the GaAs conduction band as the basic elementary gate for a quantum computer with the electron spins in the dots serving as qubits. Such a two-dot system provides the necessary two-qubit entanglement required for quantum computation. We determine the excitation spectrum of two horizontally coup

V. Guimaraes, J. J. Kolata, D. Peterson, P. Santi

The angular distribution for the breakup of 8B into 7Be+p on a 58Ni target has been measured at an incident energy of 25.75 MeV. The data are inconsistent with first-order theories but are remarkably well described by calculations including higher-order effects. The comparison with theory illustrates the importance of the exotic proton halo structure of 8B i

F. Bastianelli, S. Frolov, A. A. Tseytlin

We consider free superconformal theories of n=8 scalar multiplet in d=3 and (2,0) tensor multiplet in d=6 and compute 2-point and 3-point correlators of their stress tensors. The results for the 2-point and 3-point correlators for a single d=3 and d=6 multiplet differ from the &#34;strong-coupling&#34; AdS_4 and AdS_7 supergravity predictions by the factors

Sheng Li, Yong Zhang, Zhongyuan Zhu

We give a general decomposition of SU(N) connection and derive a generalized Skyrme-Faddeev action as the effective action of SU(N) QCD in the low energy limit. The result is obtained by separating the topological degrees which describes the non-Abelian monopoles from the dynamical degree of gauge potential, and integrating all the dynamical degrees of SU(N)

M. P. Fry

We consider the effective action for massive two-dimensional QED in flat Euclidean space-time in the background of a general square-integrable magnetic field with finite range. It is shown that its small mass limit is controlled by the chiral anomaly. New results for the low-energy scattering of electrons in 2+1 dimensions in static, inhomogenous magnetic fi

Johan Bijnens, Joaquim Prades

We show how the scheme- and scale-dependence of the short-distance operator product expansion with four-quark operators can be correctly accounted for in the framework of the $1/N_c$-expansion once the hadronization of two-quark currents has been fixed. We show formulas explicitly in the case of the $B_K$-parameter. We then use them with our earlier estimate

Boguslaw Broda, Malgorzata Bakalarska

A study of the partition function of a 3-dimensional scalar-vector model formally related via duality to the Rozansky-Witten topological sigma-model is presented. The partition function is shown to consist of such topological quantities of a 3-dimensional manifold M like a lattice sum, the Reidemeister-Ray-Singer torsion and the Massey product.

Joao Magueijo

We extend a previous bispectrum analysis of the Cosmic Microwave Background temperature anisotropy, allowing for the presence of correlations between different angular scales. We find a strong non-Gaussian signal in the ``inter-scale&#39;&#39; components of the bispectrum: their observed values concentrate close to zero instead of displaying the scatter expe

P. R. Eastham, P. B. Littlewood

We study the equilibrium properties of a system of dipole-active excitons coupled to a single photon mode at fixed total excitation. Treating the presence or absence of a trapped exciton as a two-level system produces a model that is exactly soluble. It gives a simple description of the physics of polariton condensation in optical cavities beyond the low-den

S. J. Sciutto

The AIRES (AIR-shower Extended Simulations) system is a set of programs and subroutines to realistically simulate particle showers produced after the incidence of high energy cosmic rays on the Earth's atmosphere, and to manage all the related output data. The current version includes a series of improvements with respect to previous releases that are explai

A. Wallraff, A. V. Ustinov, V. V. Kurin, I. A. Shereshevsky

Experiments indicating the excitation of whispering gallery type electromagnetic modes by a vortex moving in an annular Josephson junction are reported. At relativistic velocities the Josephson vortex interacts with the modes of the superconducting stripline resonator giving rise to novel resonances on the current-voltage characteristic of the junction. The

A. B. Apyan, R. O. Avakian, S. M. Darbinian, K. A. Ispirian

A method for photon linear polarization determination based on the measurement of the asymmetry of pairs produced by polarized photons in single crystals within the optimal intervals of pair particles energies is proposed. In difference to the well known methods the asymmetry in this case is essentially larger. The optimal orientation of crystal is found whi

A. M. Shvaika

A perturbation theory scheme in terms of electron hopping, which is based on the Wick theorem for Hubbard operators, is developed. Diagrammatic series contain single-site vertices connected by hopping lines and it is shown that for each vertex the problem splits into the subspaces with ``vacuum states&#39;&#39; determined by the diagonal Hubbard operators an

Mihai Visinescu

A necessary condition that a Stäckel-Killing tensor of valence 2 be the contracted product of a Killing-Yano tensor of valence 2 with itself is re-derived for a Riemannian manifold. This condition is applied to the generalized Euclidean Taub-NUT metrics which admit a Kepler type symmetry. It is shown that in general the Stäckel-Killing tensors involved in th

Andrew M. Martin, Markus Buttiker

In the white-noise limit current correlations measured at different contacts of a mesoscopic conductor are negative due to the antisymmetry of the wave function (Pauli principle). We show that current fluctuations at capacitive contacts induced via the long range Coulomb interaction as consequence of charge fluctuations in the mesoscopic sample can be {\it p