June 2000 arXiv papers — page 9

Mladen Bozin

From the curved spacetime Lagrangian the first approximation scalar particle quantum equation was obtained following the canonical formalism. The roots of this equation in Schwarzschild's pseudo flat space were found. As it was shown in a more general curved spacetime it is tedious to find equation's roots. The massless particle limiting case was con

Yuan-Zhong Zhang, Jun Luo, Yu-Xin Nie

We study two type effects of gravitational field on mechanical gyroscopes (i.e. rotating extended bodies). The first depends on special relativity and equivalence principle. The second is related to the coupling (i.e. a new force) between the spins of mechanical gyroscopes, which would violate the equivalent principle. In order to give a theoretical predicti

P. Desgrolard, M. Giffon, E. Martynov, E. Predazzi

The exchange-degeneracy of the mesonic $f$, $ω$, $ρ$ and $a_{2}$ Regge trajectories, dominant at moderate and high energies in hadron elastic scattering, is analyzed from two viewpoints. The first one concerns the masses of the resonances lying on these trajectories; the second one deals with the total cross-sections and the ratios of the real to the imagina

P. Facchi, H. Nakazato, S. Pascazio

The temporal evolution of an unstable quantum mechanical system undergoing repeated measurements is investigated. In general, by changing the time interval between successive measurements, the decay can be accelerated (inverse quantum Zeno effect) or slowed down (quantum Zeno effect), depending on the features of the interaction Hamiltonian. A geometric crit

Taichi Itoh, Phillial Oh

We consider higher derivative CP(N) model in 2+1 dimensions with the Wess-Zumino-Witten term and the topological current density squared term. We quantize the theory by using the auxiliary gauge field formulation in the path integral method and prove that the extended model remains renormalizable in the large N limit. We find that the Maxwell-Chern-Simons th

Taichi Itoh, Phillial Oh

We construct a fourth-order derivative CP(N) model in 1+1 dimensions by incorporating the topological charge density squared term into the Lagrangian. We quantize the theory by reformulating with auxiliary fields and then performing the path integral explicitly. We discuss the renormalizability in the large N limit and relevance of the effective action with

W. Y. Wang, Y. L. Wu

Within the complete heavy quark effective field theory (HQEFT), the QCD sum rule approach is used to evaluate the decay constants including 1/m_Q corrections and the Isgur-Wise function and other additional important wave functions concerned at 1/m_Q for the heavy-light mesons. The 1/m_Q corrections to the scaling law f_M \sim F/\sqrt{m_M} are found to be sm

P. Castelo Ferreira, F. P. Mancini, M. Tragtenberg

This paper has been withdrawn by the authors due to several major changes in concepts and results. New version will follow briefly as a new e-print.

Weidong Li, Alexei V. Filippenko, R. R. Treffers, A. G. Riess

We have compiled a sample of 45 Type Ia supernovae (SNe Ia) discovered by the Lick Observatory Supernova Search (LOSS) and the Beijing Astronomical Observatory Supernova Survey (BAOSS), and determined the rate of spectroscopically peculiar SNe Ia (i.e., SN 1986G-like, SN 1991bg-like, and SN 1991T-like objects) and the luminosity function of SNe Ia. Because o

Weidong Li, Alexei V. Filippenko, Adam G. Riess

We have performed Monte Carlo simulations of type Ia supernova (SN Ia) surveys to quantify their efficiency in discovering peculiar overluminous and underluminous SNe Ia. We determined how the type of survey (magnitude-limited, distance-limited, or a hybrid) and its characteristics (observations frequency and detection limit) affect the discovery of peculiar

A. F. Huss, N. Peer, R. Lammegger, E. A. Korsunsky

We demonstrate the efficient generation of Raman sidebands in a medium coherently prepared in a dark state by continuous-wave low-intensity laser radiation. Our experiment is performed in sodium vapor excited in $Λ$ configuration on the D$_{1}$ line by two laser fields of resonant frequencies $ω_{1}$ and $ω_{2}$, and probed by a third field $% ω_{3}$. First-

G. P. Berman, F. Borgonovi, F. M. Izrailev, V. I. Tsifrinovich

We examine a single-pulse preparation of the uniform superpositional wave function, which includes all basis states, in a spin quantum computer. The effective energy spectrum and the errors generated by this pulse are studied in detail. We show that, in spite of the finite width of the energy spectrum bands, amplitude and phase errors can be made reasonably

A. Tomita

A solid state device to discriminate all the four Bell states is proposed. The device is composed of controlled absorption crystals, rotators, and retarders. The controlled absorption, where the state of one photon affects the absorption of the other photon, is realized by two photon absorption in a cubic crystal. The controlled absorption crystal detects a

N. E. Bonesteel

The possibility of using the two-fold topological degeneracy of spin-1/2 chiral spin liquid states on the torus to construct quantum error correcting codes is investigated. It is shown that codes constructed using these states on finite periodic lattices do not meet the necessary and sufficient conditions for correcting even a single qubit error with perfect

Mikhail V. Ivanov

Fully numerical mesh solutions of 2D and 3D quantum equations of Schroedinger and Hartree-Fock type allow us to work with wavefunctions which possess a very flexible geometry. This flexibility is especially important for calculations of atoms and molecules in strong external fields where neither the external field nor the internal interactions can be conside

M. Bleicher, J. Randrup, R. Snellings, X. -N. Wang

The factorial moments of the pion multiplicity distributions are calculated with HIJING and UrQMD and found to be independent of the pT range included, in contrast to recent simulations with the linear sigma model which leads to large enhancements for pions with transverse kinetic energies below 200 MeV. This supports the use of the ratio of the factorial mo

M. M. Sharma, A. R. Farhan

Evolution of the shell structure of nuclei near the neutron drip line is investigated in the Relativistic Hartree-Bogoliubov (RHB) theory. By introducing the vector self-coupling of $ω$ meson in the RHB theory, we reproduce successfully the experimental data on the shell effects about the waiting-point nucleus $^{80}$Zn. With this basis, it is shown that the

S. Liran, A. Marinov, N. Zeldes

A semiempirical shell model mass equation applicable to superheavy elements up to Z = 126 is presented and shown to have a high predictive power. The equation is applied to the recently discovered superheavy nuclei Z = 118, A = 293 and Z = 114, A = 289 and their decay products.

K. Markenroth, L. Axelsson, S. Baxter, M. J. G. Borge

The level structure of the unbound nucleus 11N has been studied by 10C+p elastic resonance scattering in inverse geometry with the LISE3 spectrometer at GANIL, using a 10C beam with an energy of 9.0 MeV/u. An additional measurement was done at the A1200 spectrometer at MSU. The excitation function above the 10C+p threshold has been determined up to 5 MeV. A

Boris Chirikov

Large entropy fluctuations in a nonequilibrium steady state of classical mechanics were studied in extensive numerical experiments on a simple 2-freedom model with the so-called Gauss time-reversible thermostat. The local fluctuations (on a set of fixed trajectory segments) from the average heat entropy absorbed in thermostat were found to be non-Gaussian. A

A. S. Carstea

Extending the gauge-invariance principle for $τ$ functions of the standard bilinear formalism to the supersymmetric case, we define ${\cal N}=1$ supersymmetric Hirota bilinear operators. Using them we bilinearize supersymmetric nonlinear evolution equations. The super-soliton solutions are discussed. As a quite strange paradox it is shown that the Lax integr

Kurt Johansson

Consider an $N\times N$ hermitian random matrix with independent entries, not necessarily Gaussian, a so called Wigner matrix. It has been conjectured that the local spacing distribution, i.e. the distribution of the distance between nearest neighbour eigenvalues in some part of the spectrum is, in the limit as $N\to\infty$, the same as that of hermitian ran

Michel Dubois-Violette

These notes contain a survey of some aspects of the theory of graded differential algebras and of noncommutative differential calculi as well as of some applications connected with physics. They also give a description of several new developments.

Toufik Mansour, Alek Vainshtein

We find an explicit expression for the generating function of the number of permutations in S_n avoiding a subgroup of S_k generated by all but one simple transpositions. The generating function turns out to be rational, and its denominator is a rook polynomial for a rectangular board.

Claudio Hermida

Given a 2-category $\twocat{K}$ admitting a calculus of bimodules, and a 2-monad T on it compatible with such calculus, we construct a 2-category $\twocat{L}$ with a 2-monad S on it such that: (1)S has the adjoint-pseudo-algebra property. (2)The 2-categories of pseudo-algebras of S and T are equivalent. Thus, coherent structures (pseudo-T-algebras) are trans

B. Toen

We define and compare two different definitions of Chow motives for Deligne-Mumford stacks, associated with two definitions of Chow rings. The main result we prove is that both categories of motives are equivalent to the usual category of motives of algebraic varieties, but the motives of a given stack associated with both theories are not isomorphic. We wil

Nikita Sidorov

Let $T$ be an algebraic automorphism of $\mathbb{T}^{m}$ having the following property: the characteristic polynomial of its matrix is irreducible over $\mathbb{Q}$, and a Pisot number $β$ is one of its roots. We define the mapping $ϕ_{\mathbf{t}}$ acting from the two-sided $β$-compactum onto $\mathbb{T}^{m}$ as follows: \[ ϕ_{\mathbf{t}}(\barε)= \sum_{k\in\

Holger Spielberg

We study the fix point components of the big torus action on the moduli space of stable maps into a smooth projective toric variety, and apply Graber and Pandharipande's localization formula for the virtual fundamental class to obtain an explicit formula for the Gromov-Witten invariants of toric varieties. Using this formula we compute all genus-0 3-poin

Juan Gonzalez-Meneses

We prove that the pure braid groups on closed, orientable surfaces are bi-orderable, and that the pure braid groups on closed, non-orientable surfaces have generalized torsion, thus they are not bi-orderable.

Michele Grassi

In the first part of this paper we begin the study of polysymplectic manifolds, and of their relationship with PDE's. This notion provides a generalization of symplectic manifolds which is very well suited for the geometric study of PDE's with values in a smooth manifold. Some of the standard tools of analytical mechanics, such as the Legendre transf

R. Brak, J. W. Essam, A. L. Owczarek

We state and prove several theorems that demonstrate how the coordinate Bethe Ansatz for the eigenvectors of suitable transfer matrices of a generalised inhomogeneous five-vertex model on the square lattice, given certain conditions hold, is equivalent to the Gessel-Viennot determinant for the number of configurations of $N$ non-intersecting directed lattice

Anand Dessai

Let $M$ be a simply-connected closed manifold of dimension $\geq 5$ which does not admit a metric with positive scalar curvature. We give necessary conditions for $M$ to admit a scalar-flat metric. These conditions involve the first Pontrjagin class and the cohomology ring of $M$. As a consequence any simply-connected scalar-flat manifold of dimension $\geq

Michel Dubois-Violette

These notes contain a survey of some aspects of the theory of differential modules and complexes as well as of their generalization, that is, the theory of $N$-differential modules and $N$-complexes. Several applications and examples coming from physics are discussed. The commun feature of these physical applications is that they deal with the theory of cons

R. Arnowitt, B. Dutta

Recent advances in 11 dimensional Horava-Witten M-theory based on non-standard embeddings with torus fibered Calabi-Yau manifolds have allowed the construction of three generation models with Wilson line breaking to the Standard Model gauge symmetry. Central to these constructions is the existence of a set of 5-branes in the bulk. We examine within this fram

Thibault Damour, Marc Henneaux

Some spatially homogeneous Bianchi type I cosmological models filled with homogeneous ``electric'' $p$-form fields are shown to mimic the never-ending oscillatory behaviour of generic string cosmologies established recently. The validity of the ``Kasner-free-flights plus collisions-on-potential-walls'' picture is also illustrated in the case

S. Majid

Quantum groups emerged in the latter quarter of the 20th century as, on the one hand, a deep and natural generalisation of symmetry groups for certain integrable systems, and on the other as part of a generalisation of geometry itself powerful enough to make sense in the quantum domain. Just as the last century saw the birth of classical geometry, so the pre

S. Majid

This is an introduction for nonspecialists to the noncommutative geometric approach to Planck scale physics coming out of quantum groups. The canonical role of the `Planck scale quantum group' $C[x]\bicross C[p]$ and its observable-state T-duality-like properties are explained. The general meaning of noncommutativity of position space as potentially a ne

L. Hoffmann, L. Mesref, W. Ruehl

We develop a method of singularity analysis for conformal graphs which, in particular, is applicable to the holographic image of AdS supergravity theory. It can be used to determine the critical exponents for any such graph in a given channel. These exponents determine the towers of conformal blocks that are exchanged in this channel. We analyze the scalar A

Hyeong-Chan Kim, Jae Hyung Yee, Mu-In Park

We find two types [called (S) and (A)] of new vacuum solutions of open, flat, and closed universes which are inflating in the brane-world scenario. We show that the warp factor of the stabilized metric is universal for the three different kinds of universes. For (S) type solution, we show that one positive-tension brane universe solution is admitted as well

D. M. Medeiros, R. R. Landim, C. A. S. Almeida

Starting from a recently proposed abelian topological model in (2+1) dimensions, we use the method of the consistent deformations to prove that a topologically massive model involving the Kalb-Ramond two form field does not admit a nonabelian generalization. The introduction of a connection-type one form field keeps the previous result. However we show that

Lorenzo Magnea

The quark form factor is known to exponentiate within the framework of dimensionally regularized perturbative QCD. The logarithm of the form factor is expressed in terms of integrals over the scale of the running coupling. I show that these integrals can be evaluated explicitly and expressed in terms of renormalization group invariant analytic functions of t

B. Dressler, M. Maul, C. Weiss

We study the twist-4 contribution to the unpolarized nucleon structure functions, F_L and F_2, in an approach where the vacuum structure of QCD is described by a dilute medium of instantons ($\barρ/ \bar R \ll 1$). The dominant power corrections come from the twist-4 quark-gluon operators and are of the order $1/(\barρ^2 Q^2)$. The contributions from four-qu

H. J. Drescher, M. Hladik, S. Ostapchenko, T. Pierog

We argue that most commonly used models for nuclear scattering at ultra-relativistic energies do not treat energy conservation in a consistent fashion. Demanding theoretical consistency as a minimal requirement for a realistic model, we provide a solution for the above-mentioned problem, the so-called ``Parton-Based Gribov-Regge Theory''. In order to

R. Peschanski

We apply the AdS/CFT correspondence to derive expressions for the scattering amplitudes at high energy for gauge theories at strong coupling. A method is proposed based on the computation of correlators of Wilson loop operators by their stringy duals in AdS spaces using either the supergravity (weak field) or classical (minimal surface) approximations.

I. I. Bigi

Even in 2010 the CKM parameters $V_{cs}$, $V_{cd}$ and $V_{ub}$ will be known with less than desirable accuracy; the discovery potential for New Physics in charm decays -- in particular their CP asymmetries -- will be far from exhausted; important tests of our theoretical tools will not have been performed. I sketch the impact a $ν$fact could have in these a

A. P. Bakulev, S. V. Mikhailov, R. Ruskov

We present new models of the rho-meson leading-twist light-cone distribution amplitudes based on the QCD sum rule approach with nonlocal condensates. Their shapes differ noticeably from that known in the literature. The phenomenological consequences for physically important process B --> rho e nu are discussed in the framework of the light-cone sum rules. Th

E. Frlez, Ch. Broennimann, B. Krause, D. Pocanic

We have measured scintillation properties of pure CsI crystals used in the shower calorimeter built for a precise determination of the pi+ -> pi0 e+ nu decay rate at the Paul Scherrer Institute (PSI). All 240 individual crystals painted with a special wavelength-shifting solution were examined in a custom-build detection apparatus (RASTA=radioactive source t

CDF Collaboration, T. Affolder

We report on the first measurement of the rapidity distribution dsigma/dy over nearly the entire kinematic region of rapidity for e^+e^- pairs in the Z-boson region of 66<M_{ee}<116 GeV/c^2 and at higher mass M_{ee}>116 GeV/c^2. The data sample consists of 108 pb^{-1} of ppbar collisions at \sqrt{s}=1.8 TeV taken by the Collider Detector at Fermilab during 1

Simonetta Frittelli, Ezra T. Newman

We describe an approach to the issue of the singularities of null hypersurfaces, due to the focusing of null geodesics, in the context of the recently introduced formulation of GR via null foliations.

Remo Garattini

Following the subtraction procedure for manifolds with boundaries, we calculate by variational methods, the Schwarzschild-Anti-de Sitter and the Anti-de Sitter space energy difference. By computing the one loop approximation for TT tensors we discover the existence of an unstable mode at zero temperature, which can be stabilized by the boundary reduction met

Yi-Dong Shen, Li-Yan Yuan, Jia-Huai You

We introduce a method of verifying termination of logic programs with respect to concrete queries (instead of abstract query patterns). A necessary and sufficient condition is established and an algorithm for automatic verification is developed. In contrast to existing query pattern-based approaches, our method has the following features: (1) It applies to a

Subir Sachdev

This paper presents a unified perspective on the results of two recent works (C. Buragohain and S. Sachdev cond-mat/9811083 and S. Sachdev cond-mat/9810399) along with additional background. We describe the low frequency, non-zero temperature, order parameter relaxational dynamics of a number of systems in the vicinity of a quantum critical point. The dynami

Mathias Wagner

A recently demonstrated quantum electron pump is discussed within the framework of photon-assisted tunneling. Due to lack of time-reversal symmetry, different results are obtained for the pump current depending on whether or not final-state Pauli blocking factors are used when describing the tunneling process. Whilst in both cases the current depends quadrat

A. R. Denton

Interparticle interactions in charge-stabilized colloidal suspensions, of arbitrary salt concentration, are described at the level of effective interactions in an equivalent one-component system. Integrating out from the partition function the degrees of freedom of all microions, and assuming linear response to the macroion charges, general expressions are o

Sherryl Manalo, Ulf Klein

We compare the theoretical anisotropic upper critical field $H_{C}(Θ,T)$ of a quasi-two-dimensional d-wave superconductor with recent $H_{c2}$ data for the layered organic superconductor $κ-(BEDT-TTF)_2Cu(NCS)_2$. We find agreement both with regard to the angular and the temperature dependence of $H_{C}$. This supports the suggestion that the Fulde-Ferrell-L

D. Mihailovic, J. Demsar, R. Hudej, V. V. Kabanov

We show that low-energy spectral features in the cuprates can be separated into different components by the measurement of the recombination dynamics of different low-energy excitations in real-time using femtosecond laser spectroscopy. Quasiparticle (QP) recombination across the gap and intra-gap localized state relaxation processes exhibit qualitatively di

Maziar Nekovee, Peter V. Coveney, Hudong Chen, Bruce M. Boghosian

We develop our recently proposed lattice-Boltzmann method for the non-equilibrium dynamics of amphiphilic fluids (Chen, Boghosian, Coveney and Nekovee, Proc. Roy. Soc. London A, 456, 1431 (2000).) Our method maintains an orientational degree of freedom for the amphiphilic species and models fluid interactions at a microscopic level by introducing self-consis

J. Demsar, R. Hudej, J. Karpinski, V. V. Kabanov

Following recent progress in understanding the relaxation dynamics of photoexcited carriers in materials exhibiting a small gap in the low-energy excitation spectrum we have performed pump-probe measurements on near optimally doped Hg-1223. We show that the behavior is very similar as in optimally-doped YBCO, where the data can be interpreted with the coexis

J. Schnack

Systematic properties of the first excited state are presented for various ring sizes and spin quantum numbers which are only partly covered by the theorem of Lieb, Schultz and Mattis. For odd ring sizes the first excited energy eigenvalue shows unexpected degeneracy and related shift quantum numbers. As a byproduct the ground state energy as well as the ene

Alexander K. Hartmann, Martin Weigt

The vertex-cover problem is studied for random graphs $G_{N,cN}$ having $N$ vertices and $cN$ edges. Exact numerical results are obtained by a branch-and-bound algorithm. It is found that a transition in the coverability at a $c$-dependent threshold $x=x_c(c)$ appears, where $xN$ is the cardinality of the vertex cover. This transition coincides with a sharp

R. Parthasarathy, R. Sridhar

By considering the enlarged thermal system including the heat bath, it is shown that this system has supersymmetry which is not broken at finite temperature. The super algebra is constructed and the Hamiltonian is expressed as the anti-commutator of two kinds of super charges. With this Hamiltonian and the thermal vacuum $\mid 0(β)>$, this supersymmetry is f

Niurka R. Quintero, Angel Sanchez, Franz G. Mertens

We study whether or not sine-Gordon kinks exhibit internal modes or ``quasimodes.&#39;&#39; By considering the response of the kinks to ac forces and initial distortions, we show that neither intrinsic internal modes nor ``quasimodes&#39;&#39; exist in contrast to previous reports. However, we do identify a different kind of internal mode bifurcating from th

Niurka R. Quintero, Angel Sanchez, Franz G. Mertens

We study the dynamics of $ϕ^4$ kinks perturbed by an ac force, both with and without damping. We address this issue by using a collective coordinate theory, which allows us to reduce the problem to the dynamics of the kink center and width. We carry out a careful analysis of the corresponding ordinary differential equations, of Mathieu type in the undamped c

Yoshihiro Nishiyama

Chiral order of the Josephson-junction ladder with half a flux quantum per plaquette is studied by means of the exact diagonalization method. We consider an extreme quantum limit where each superconductor grain (order parameter) is represented by S=1/2 spin. So far, the semi-classical S -> \infty case, where each spin reduces to a plane rotator, has been con

Pasquale Blasi, Ravi Sheth

The decay of very heavy metastable relics of the Early Universe can produce ultra-high energy cosmic rays (UHECRs) in the halo of our own Galaxy. On distance scales of the order of the halo size, energy losses are negligible---no Greisen-Zatsepin-Kuzmin cutoff is expected. In this letter we show that, as a consequence of the hierarchical build up of the halo

M. Polletta, T. J. -L. Courvoisier, E. J. Hooper, B. J. Wilkes

Continuum observations at radio, millimetre, infrared and soft X-ray energies are presented for a sample of 22 quasars, consisting of flat and steep spectrum radio loud, radio intermediate and radio quiet objects. The primary observational distinctions, among the different kinds of quasars in the radio and IR energy domains are studied using large observatio

D. I. Dinescu, S. R. Majewski, T. M. Girard, K. M. Cudworth

We have measured the absolute proper motion of the young globular cluster Pal 12 with respect to background galaxies, using plate material spanning a 40-year time baseline, and measuring stars down to a magnitude V~22. The measured absolute proper motion has an uncertainty of 0.3 mas/yr in each coordinate. Pal 12&#39;s young age for a globular cluster led to

Sebastian Wolf, Bringfried Stecklum, Thomas Henning

We present the results of a study performed with the goal to investigate whether low-mass pre-main sequence binary stars are formed by multiple fragmentation or via stellar capture. If binaries form preferentially by fragmentation, we expect their disks to be co-planar. On the other hand, the capture scenario will lead to a random distribution of disk orient

M. Demianski, A. G. Doroshkevich, V. Turchaninov

The observed redshift distribution of Ly-$α$ lines and metal systems is examined in order to discriminate and to trace the evolution of structure elements observed in the galaxy distribution, at small redshifts, and to test the theoretical description of structure evolution. We show that the expected evolution of filamentary component of structure describes

M. Demianski, A. Doroshkevich, V. Turchaninov

The main observed properties of Ly-$α$ absorbers are investigated on the basis of theoretical model of formation and evolution of DM structure elements. This model is generally consistent with simulations of absorbers formation and with statistical description of structure evolution based on the Zel&#39;dovich theory. The analysis of redshift variations of c

B. D. Blout, E. J. Daw, M. P. Decowski, Paul T. P. Ho

The axion is a hypothetical elementary particle and a cold dark matter candidate. It could dominate potential wells of most astrophysical objects. Axions spontaneously decay into nearly monochromatic microwave photons. We present results from a radio telescope search for these axion decay photons of mass between 298 and 363 micro-eV in Local Group dwarf gala

Hugo Martel, Paul R. Shapiro

As an idealized model of the effects of energy release by supernovae during galaxy formation, we consider an explosion at the center of a halo which forms at the intersection of filaments in the plane of a cosmological pancake by gravitational instability during pancake collapse. Such halos resemble the virialized objects found in N-body simulations in a CDM

G. Giardino, F. Favata

We present the detection of CII and CII* absorption in the z = 3.0543 damped Ly-alpha system toward Q0000-2619. The derived population ratio implies a fine structure excitation temperature between 19.6 and 21.6 K. The upper value sets a strict upper limit on the CMB temperature at this redshift, which is consistent with the predicted value of 11.05 K from st

L. Sidoli, A. N. Parmar, T. Oosterbroek

Results of a 1999 November 16--17 BeppoSAX observation of the low-mass X-ray binary X2127+119 located in the globular cluster NGC7078 are presented. The system is believed to be one where the central neutron star is normally obscured by the accretion disk, and only X-rays scattered into our line of sight by an extended accretion disk corona (ADC) are observe

Riccardo Scarpa, C. Megan Urry, Paolo Padovani, Daniela Calzetti

The HST NICMOS Camera 2 was used for H-band imaging of 12 BL Lacertae objects taken from the larger sample observed with the WFPC2 in the R band (Urry et al. 2000; Scarpa et al. 2000). Ten of the 12 BL Lacs are clearly resolved, and the detected host galaxies are large, bright ellipticals with average H-band absolute magnitude M=-26.2+-0.45 mag and effective

W. Hillebrandt, J. C. Niemeyer

Because calibrated light curves of Type Ia supernovae have become a major tool to determine the local expansion rate of the Universe and also its geometrical structure, considerable attention has been given to models of these events over the past couple of years. There are good reasons to believe that perhaps most Type Ia supernovae are the explosions of whi

STACEE Collaboration, S. Oser, D. Bhattacharya, L. M. Boone

The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a new ground-based atmospheric Cherenkov telescope for gamma-ray astronomy. STACEE uses the large mirror area of a solar heliostat facility to achieve a low energy threshold. A prototype experiment which uses 32 heliostat mirrors with a total mirror area of ~ 1200\unit{m^2} has been construc

F. Zagury

In 1998 Gordon, Witt and Friedmann wrote of detection of ERE in diffuse galactic light at high latitudes. The comparaison of diffuse galactic light and starlight over a few regions of the sky cannot, according to the authors, be fully explained by extinction of starlight. 50% of the red interstellar light needs to come from an interstellar emitting process.

J. Rossa, R. -J. Dettmar

We present narrowband H-alpha imaging data of a small survey of nearby edge-on spiral galaxies, aiming at the detection of `extraplanar&#39; diffuse ionized gas (DIG). A few of our studied edge-on spirals show signs of disk-halo interaction (DHI), where extended line emission far above the galactic plane of these galaxies is detected. In some cases an extrap

A. Rosenberg, A. Aparicio, I. Saviane, G. Piotto

In this paper we present the second and final part of a large and photometrically homogeneous CCD color-magnitude diagram (CMD) data base, comprising 52 nearby Galactic globular clusters (GGC) imaged in the V and I bands. The catalog has been collected using only two telescopes (one for each hemisphere). The observed clusters represent 75% of the known Galac

M. Perri, P. Giommi

We present an analysis of the spatial fluctuations of the 2-10 keV Cosmic X-ray Background (CXB) as measured from 22 high galactic latitude (|b| > 25 deg) fields observed with the MECS instrument on-board BeppoSAX. This technique allowed us to probe extragalactic source counts a factor 3-4 fainter than is possible with direct measurements of pointlike source

Sujan Sengupta, Vinod Krishan

We investigate the formation of methane line at 2.3 ${\rm μm}$ in Brown Dwarf Gliese 229B. Two sets of model parameters with (a) $T_{\rm eff}=940 $K and $\log (g) =5.0$, (b) $T_{\rm eff}=1030 $K and $ \log(g)=5.5$ are adopted both of which provide excellent fit for the synthetic continuum spectra with the observed flux at a wide range of wavelengths. In the

M. Sarzi, E. M. Corsini, A. Pizzella, J. C. Vega Beltran

We report the case of the early-type disk galaxy NGC 4672 as a new example of a galaxy characterized by the orthogonal geometrical decoupling between bulge and disk. The morphological features of this galaxy are discussed as well as the velocity curves and velocity dispersion profiles of stars and ionized gas along both its major and minor axis. We conclude

J. Barnstedt, N. Kappelmann, I. Appenzeller, A. Fromm

During the second flight of the ORFEUS-SPAS mission in November/December 1996, the Echelle spectrometer was used extensively by the Principal and Guest Investigator teams as one of the two focal plane instruments of the ORFEUS telescope. We present the in-flight performance and the principles of the data reduction for this instrument. The wavelength range is

J. Barnstedt, W. Gringel, N. Kappelmann, M. Grewing

During the second flight of the ORFEUS-SPAS mission in November/December 1996, the Echelle spectrometer was used extensively by the Principal and Guest Investigator teams as one of the two focal plane instruments of the ORFEUS telescope. The spectrum of HD 93521 was obtained during this mission with a total integration time of 1740 s. This spectrum shows num

Eiichiro Komatsu, Hiroshi Matsuo, Tetsu Kitayama, Makoto Hattori

We report on mapping observations toward the region of the most luminous X-ray cluster RXJ1347-1145 (z=0.45) through the Sunyaev-Zel&#39;dovich effect at 21GHz and 150GHz with the Nobeyama 45-m telescope. While a low angular resolution image at 21GHz (beam-size of 76&#39;&#39;) shows a consistent feature with the ROSAT/HRI X-ray image, a higher angular resol

Jo Ann Eder, James Schombert

We present Arecibo neutral hydrogen data on a sample of optically selected dwarf galaxies. The sample ranges in HI mass from 10^6 M_sun to 5x10^9 M_sun, with a mean of 7.9x10^8 M_sun. Using estimated HI radii, the HI surface densities range from 0.6 to 20 M_sun pc^-2, all well below the critical threshold for star formation (Kennicutt 1998). M_HI/L values of

Sanjaye Ramgoolam

T-duality (Fourier-Mukai duality) and properties of classical instanton moduli spaces can be used to deduce some properties of $α^{\prime}$-corrected moduli spaces of branes for Type IIA string theory compactified on $K3$ or $T^4$. Some interesting differences between the two compactifications are exhibited.

David Garfinkle, G. Comer Duncan

We report a numerical evolution of axisymmetric Brill waves. The numerical algorithm has new features, including (i) a method for keeping the metric regular on the axis and (ii) the use of coordinates that bring spatial infinity to the edge of the computational grid. The dependence of the evolved metric on both the amplitude and shape of the initial data is

Karl Gebhardt, Ralf Bender, Gary Bower, Alan Dressler

We describe a correlation between the mass M_BH of a galaxy's central black hole and the luminosity-weighted line-of-sight velocity dispersion sigma_e within the half-light radius. The result is based on a sample of 26 galaxies, including 13 galaxies with new determinations of black hole masses from Hubble Space Telescope measurements of stellar kinematics.

S. Majid

We construct noncommutative `Riemannian manifold&#39; structures on dual quasitriangular Hopf algebras such as $C_q[SU_2]$ with its standard bicovariant differential calculus, using the quantum frame bundle formalism introduced previously. The metric is provided by the braided-Killing form on the braided-Lie algebra on the tangent space and the $n$-bein by t

Nima Arkani-Hamed, Hsin-Chia Cheng, Bogdan A. Dobrescu, Lawrence J. Hall

If the gauge fields of the Standard Model propagate in TeV-size extra dimensions, they rapidly become strongly coupled and can form scalar bound states of quarks and leptons. If the quarks and leptons of the third generation propagate in 6 or 8 dimensions, we argue that the most tightly bound scalar is a composite of top quarks, having the quantum numbers of

Enrico Nardi, Jorge I. Zuluaga

A convincing explanation for the observed pulsar large peculiar velocities is still missing. We argue that any viable particle physics solution would most likely involve the resonant production of a non-interacting neutrino $ν_s$ of mass $m_{ν_s}\sim 20$--50 keV. We propose a model where anisotropic magnetic field configurations strongly bias the resonant sp

David W. Hogg, Judith G. Cohen, Roger Blandford

A clustering analysis is performed on two samples of $\sim 600$ faint galaxies each, in two widely separated regions of the sky, including the Hubble Deep Field. One of the survey regions is configured so that some galaxy pairs span angular separations of up to 1 deg. The median redshift is $z_{med}\approx 0.55$. Strong clustering is obvious, with every penc

John Schliemann, S. M. Girvin, A. H. MacDonald

At small layer separations, the ground state of a nu=1 bilayer quantum Hall system exhibits spontaneous interlayer phase coherence and has a charged-excitation gap E_g. The evolution of this state with increasing layer separation d has been a matter of controversy. In this letter we report on small system exact diagonalization calculations which suggest that

F. R. Klinkhamer, J. Nishimura

The CPT anomaly, which was first seen in perturbation theory for certain four-dimensional chiral gauge theories, is also present in the exact result for a class of two-dimensional chiral U(1) gauge theories on the torus. Specifically, the chiral determinant for periodic fermion fields changes sign under a CPT transformation of the background gauge field. The

A. Crotts, R. Uglesich, A. Gould, G. Gyuk

January 2000 completes the first season of intensive, wide-field observations of microlensing and stellar variability in M31 by MEGA (Microlensing Exploration of the Galaxy and Andromeda) at the Isaac Newton 2.5m Telescope, the KPNO 4m, and the 1.3m and 2.5m telescopes of MDM Observatory. In preliminary analysis, we detect ~50000 variable objects, including

L. Bellier-Castella, M. J. P. Gingras, P. C. W. Holdsworth, R. Moessner

The classical Heisenberg antiferromagnet on the pyrochlore lattice is macroscopically and continuously degenerate and the system remains disordered at all temperatures, even in the presence of weak dilution with nonmagnetic ions. We show that, in stark contrast, weak bond disorder lifts the ground state degeneracy in favour of locally collinear spin configur

Friedemann Brandt, Alexander Kling, Maximilian Kreuzer

We present all NSR superstring and super-D-string actions invariant under a set of prescribed gauge transformations, and characterize completely their global symmetries. In particular we obtain locally supersymmetric Born-Infeld actions on general backgrounds in a formulation with extra target space dimensions. The nontrivial global symmetries of the superst

Shogo Tanimura

We formulate path integrals on any Riemannian manifold which admits the action of a compact Lie group by isometric transformations. We consider a path integral on a Riemannian manifold M on which a Lie group G acts isometrically. Then we show that the path integral on M is reduced to a family of path integrals on a quotient space Q=M/G and that the reduced p