December 2001 arXiv papers — page 14

Tanmoy Bhattacharya, Salman Habib, Kurt Jacobs, Kosuke Shizume

We investigate the quantum-classical transition in the delta-kicked rotor and the attainment of the classical limit in terms of measurement-induced state-localization. It is possible to study the transition by fixing the environmentally induced disturbance at a sufficiently small value, and examining the dynamics as the system is made more macroscopic. When

Glenn Decker, Om Singh

The Advanced Photon Source (APS) was commissioned in 1995 as a third-generation x-ray user facility. At that time orbit control was performed exclusively with broadband rf beam position monitors (BPMs). Since then, emphasis has been placed on incorporating x-ray beam position monitors into the orbit control algorithms. This has resulted in an order of magnit

Josef Frisch, Linda Hendirckson, Thomas Himel, Andrei Seryi

The nanometer scale beam sizes at the interaction point in linear colliders limit the allowable motion of the final focus magnets. We have constructed a prototype system to investigate the use of active vibration damping to control magnet motion. Inertial sensors are used to measure the position of a test mass, and a DSP based system provides feedback using

E. G. Bessonov, Yukio Shibata, Satoshi Sasaki, Kimihiro Ishi

Elements of a vector theory of open resonators and experiments on excitation of a fundamental mode with transverse and longitudinal polarization in such resonators are discussed.

Rudolph C. Hwa, Thomas C. Ferree

The fluctuation properties of the human electroencephalogram (EEG) time series are studied using detrended fluctuation analysis. For all 128 channels in each of 18 subjects studied, it is found that the standard deviation of the fluctuations exhibits scaling behaviors in two regions. Topographical plots of the scaling exponents reveal the spatial structure o

T. Masuda, T. Ohata, T. Asaka, H. Dewa

We integrated an injector linac control system to the SPring-8 standard system on September 2000. As a result of this integration, the SPring-8 accelerator complex was controlled by one unified system. Because the linac was continuously running as the electron beam injector not only for the SPring-8 storage ring but also for New SUBARU, we had to minimize th

A. S. Botvina, O. V. Lozhkin, W. Trautmann

Isotopic effects observed in fragmentation reactions induced by protons, deuterons, and alpha particles of incident energies between 660 MeV and 15.3 GeV on 112-Sn and 124-Sn targets are discussed. The exponential scaling of the yield ratios with the third component of the fragment isospin (N-Z)/2 is observed in all reactions, with scaling parameters that de

M. J. Vicente Vacas, E. Oset

The meson meson interaction in the scalar isoscalar channel at finite baryonic density is studied in the framework of a chiral unitary approach which generates the f0 and sigma resonances and reproduces well the meson meson phase shifts in vacuum. We investigate the sigma spectral function, its mass and its width as a function of the baryon density and discu

C. Keil, H. Lenske, C. Greiner

We introduce a microscopic and relativistic theory describing free scattering and finite nuclei for the octet baryons in a consistent quantum field theoretical framework based on Dirac-Brueckner theory and nuclear mean-field. In a first quantitative approach - yet still heuristic for dealing with the $Λ$ hyperon - the quality of the description of finite (hy

A. Keranen, F. Becattini

Enforcing exact conservation laws instead of average ones in statistical thermal models for relativistic heavy ion reactions gives raise to so called canonical effect, which can be used to explain some enhancement effects when going from elementary (e.g. pp) or small (pA) systems towards large AA systems. We review the recently developed method for computati

Mariusz Michalec

The grand-canonical version of the thermal model is used to analyze the ratios of particle abundances measured in ultra-relativistic heavy-ion collisions. Exactly the same model is applied to study the heavy-ion reactions at BNL AGS, CERN SPS, and BNL RHIC. A very good description is achieved for Pb+Pb collisions at SPS, and for Au+Au collisions at RHIC. In

Juergen Vollmer, Laszlo Matyas, Tamas Tel

In summer 1997 we were sitting with Bob Dorfman and a few other friends interested in chaotic systems and transport theory on a terrace close to Oktogon in Budapest. While taking our (decaf) coffee after a very nice Italian meal, we discussed about logarithmic divergences in the entropy production of systems with absorbing boundary conditions and their conse

Ramon Ortega, Mariano Santander

This paper contains a thorough study of the trigonometry of the homogeneous symmetric spaces in the Cayley-Klein-Dickson family of spaces of 'complex Hermitian' type and rank-one. The complex Hermitian elliptic CP^N and hyperbolic CH^N spaces, their analogues with indefinite Hermitian metric and some non-compact symmetric spaces associated to SL(N+1,

D. B. Fairlie

A further class of complex covariant field equations is investigated. These equations possess several common features: they may be solved, or partially solved in terms of implicit functional relations, they possess an infinite number of inequivalent Lagrangians which vanish on the space of solutions of the equations of motion, they are invariant under linear

Allen Knutson, Terence Tao

We generalize our puzzle formula for ordinary Schubert calculus on Grassmannians, to a formula for the T-equivariant Schubert calculus. The structure constants to be calculated are polynomials in {y_{i+1} - y_i}; they were shown (abstractly) to have positive coefficients in [Graham] math.AG/9908172. Our formula is the first to be manifestly positive in this

Carla Dionisi, Claudio Fontanari

This work is a modern revisitation of a classical paper by Alessandro Terracini, going back to 1915, which suggests an elementary but powerful method for studing Grassmann defective varieties. In particular, the case of Veronese surfaces is completely understood, giving an positive answer to the so-called Waring problem for pairs of homogeneous polynomials i

Miguel Navarro

Our number system is a magnificent tool. But it is far from perfect. Can it be improved? In this paper some possibilities are discussed, including the use of a different base or directed (negative as well as positive) numerals. We also put forward some suggestions for further research.

Volker Kaibel

The edge expansion of a graph is the minimum quotient of the number of edges in a cut and the size of the smaller one among the two node sets separated by the cut. Bounding the edge expansion from below is important for bounding the ``mixing time'' of a random walk on the graph from above. It has been conjectured by Mihail and Vazirani that the graph

William Y. C. Chen, Victor J. W. Guo

The Ramanujan polynomials were introduced by Ramanujan in his study of power series inversions. In an approach to the Cayley formula on the number of trees, Shor discovers a refined recurrence relation in terms of the number of improper edges, without realizing the connection to the Ramanujan polynomials. On the other hand, Dumont and Ramamonjisoa independen

Alexandr Yelnikov

Quantum mechanics in the presence of $δ$-function potentials is known to be plagued by UV divergencies which result from the singular nature of the potentials in question. The standard method for dealing with these divergencies is by constructing self-adjoint extensions of the corresponding Hamiltonians. Two particularly interesting examples of this kind are

Dumitru Astefanesei, Robert C. Myers

We generalize the basic enhancon solution of Johnson, Peet and Polchinski by constructing solutions without spherical symmetry. A careful consideration of boundary conditions at the enhancon surface indicates that the interior of the supergravity solution is still flat space in the general case. We provide some explicit analytic solutions where the enhancon

Sonia Stanciu

This is a brief review of some recent results on the geometric approach to symmetric D-branes in group manifolds, both twisted and untwisted. We describe the geometry of the gluing conditions and the quantisation condition in the boundary WZW model, and we illustrate this by determining the consistent twisted and untwisted D-branes in the Lie group SU_3.

T. Dereli, R. W. Tucker

We argue that a spontaneous breakdown of local Weyl invariance offers a mechanism in which gravitational interactions contribute to the generation of particle masses and their electric charge. The theory is formulated in terms of a spacetime geometry whose natural connection has both dynamic torsion and non-metricity. Its structure illuminates the role of dy

Sarmishtha Kumar

We consider models involving the higher (third) derivative extension of the abelian Chern-Simons (CS) topological term in D=2+1 dimensions. The polarisation vectors in these models reveal an identical structure with the corresponding expressions for usual models which contain, at most, quadratic structures. We also investigate the Hamiltonian structure of th

Seok Kim, Choonkyu Lee

We present the N=2 supersymmetric formulation for the classical and quantum dynamics of a nonrelativistic charged particle on a curved surface in the presence of a perpendicular magnetic field. For a particle moving on a constant-curvature surface in a constant magnetic field, our Hamiltonian possesses the shape-invariance property in addition. On the surfac

A. A. Arkhipov

Simple theoretical formula describing the global structure of pp and p\bar p total cross-secrions in the whole range of energies available up today has been derived. The fit to the experimental data with the formula has been made. It is shown that there is a very good correspondence of the theoretical formula to the existing experimental data.

Gerhard Baur, Kai Hencken, Dirk Trautmann, Serguei Sadovsky

Due to coherence, there are strong electromagnetic fields of short duration in very peripheral collisions. They give rise to photon-photon and photon-nucleus collisions with a high flux up to an invariant mass region hitherto unexplored experimentally. After a general survey of the field equivalent photon numbers and photon-photon luminosities, especially fo

Steve Reucroft

A brief review of the energy spectrum of primary cosmic rays above $10^{10}$ eV and the measurement techniques used to investigate the ultra high energy ones is given. This is followed by a discussion of the atmospheric shower profile of the highest energy event observed using the Fly's Eye detector. Finally, cosmic ray simulation tools are discussed and

Joseph Schechter

A brief introduction to the effective Lagrangian treatment of QCD (in the sense of using fields representing physical particles rather than quarks and gluons) will be given. The historical evolution of the subject will be discussed. Some background material related to a recent model for Gamma Ray Bursters will be given. Finally, some recent work on low energ

Chao-Shang Huang, Chun Liu, Shi-Lin Zhu

The HQET sum rule analysis for the Λ_b matrix element of the four-quark operator relevant to its lifetime is reported. Our main conclusion is that the lifetime ratio τ(Λ_b)/τ(B^0) can be as low as 0.91.

Jean-Paul Blaizot

The entropy of the quark-gluon plasma can be calculated from QCD using (approximately) self-consistent approximations. Lattice results for pure gauge theories are accurately reproduced down to temperatures of the order of 2.5$T_c$. Comparisons with other approaches to the thermodynamics of the quark-gluon plasma are briefly discussed.

Bernd A. Kniehl, Lennart Zwirner

We calculate the cross section of J/psi plus jet associated production in ep deep-inelastic scattering within the factorization formalism of nonrelativistic quantum chromodynamics. Our analytic results disagree with previous analyses, both for the colour-singlet and colour-octet channels. Our theoretical predictions agree reasonably well with recent data tak

Holger Gies, Kurt Langfeld

A numerical technique for calculating effective actions of electromagnetic backgrounds is proposed, which is based on the string-inspired worldline formalism. As examples, we consider scalar electrodynamics in three and four dimensions to one-loop order. Beyond the constant-magnetic-field case, we analyze a step-function-like magnetic field exhibiting a nonl

M. Iwasaki, K. Yamaguchi, O. Miyamura

We investigate fluctuation effects of a gap parameter in color-superconductors. The fluctuation modes in the super phase are described by two scalar fields of diquarks. One of them is a Nambu-Goldstone boson and the other is a diquark boson whose mass is about twice of the gap energy (an extended quasi-supersymmetry). In the normal phase the fluctuation beco

A. Aste, G. Baur, K. Hencken, D. Trautmann

The results concerning the $e^+e^-$ production in peripheral highly relativistic heavy-ion collisions presented in a recent paper by Baltz {\em{et al.}} are rederived in a very straightforward manner. It is shown that the solution of the Dirac equation directly leads to the multiplicity, i.e. to the total number of electron-positron pairs produced by the ele

S. Kretzer, D. Mason, F. Olness

Experimental analyses of charged current deep inelastic charm production -- as observed through dimuon events in neutrino-iron scattering -- measure the strangeness component of the nucleon sea. A complete analysis requires a Monte Carlo simulation to account for experimental detector acceptance effects; therefore, a fully differential theoretical calculatio

S. Dawson

Higgs boson production rates at hadron colliders are reviewed with particular emphasis on progress in the calculation of higher order QCD effects. Emphasis is placed on the uncertainties in the predictions for Higgs boson production. A firm understanding of these uncertainties is crucial for extracting new physics signals.

J. Budczies, S. Nonnenmacher, Ya. Shnir, M. R. Zirnbauer

The color-flavor transformation, an identity that connects two integrals, each of which is over one of a dual pair of Lie groups acting in the fermionic Fock space, is extended to the case of the special unitary group. Using this extension, a toy model of lattice QCD is studied: N_f species of spinless fermions interacting with strongly coupled SU(N_c) latti

H. J. Yo, J. M. Nester

We examine several higher spin modes of the Poincaré gauge theory (PGT) of gravity using the Hamiltonian analysis. The appearance of certain undesirable effects due to non-linear constraints in the Hamiltonian analysis are used as a test. We find that the phenomena of field activation and constraint bifurcation both exist in the pure spin 1 and the pure spin

Marcelo S. Berman, Luis A. Trevisan

We show that Gravitational Waves are exponetially amplified in the inflationary phase in Brans-Dicke theory, so that it would be possible to detect them and in this way verify several features of physical reality.

Naomi Dushay

With the increasing technical sophistication of both information consumers and providers, there is increasing demand for more meaningful experiences of digital information. We present a framework that separates digital object experience, or rendering, from digital object storage and manipulation, so the rendering can be tailored to particular communities of

G. Gervais, K. Yawata, N. Mulders, W. P. Halperin

The nucleation of the first order phase transition of superfluid 3He-B from superfluid 3He-A is quite remarkable since it requires a seed of the order of a micron. We have studied this nucleation for 3He confined to a very dilute silica aerogel. This dirty superfluid behaves in a manner similar to previous reports for the pure superfluid. But we have discove

Özgür E. Müstecaplıoğlu, L. You

We present a family of generalized unitary transformations that simplifies the Hamiltonian for a harmonically trapped two level atom (or ion) interacting with a plane wave laser field. Novel near resonant single as well as double vibrational phonon dynamical regimes are found. The validity condition of the often used motional rotating wave approximation (MRW

C. Keller, Florian Marquardt, C. Bruder

We consider an experimentally relevant model of a geometric ratchet in which particles undergo drift and diffusive motion in a two-dimensional periodic array of obstacles, and which is used for the continuous separation of particles subject to different forces. The macroscopic drift velocity and diffusion tensor are calculated by a Monte-Carlo simulation and

Rodrigo P. A. Lima, Marcelo L. Lyra, Elton M. Nascimento, Antonio D. de Jesus

We study one-magnon excitations in a random ferromagnetic Heisenberg chain with long-range correlations in the coupling constant distribution. By employing an exact diagonalization procedure, we compute the localization length of all one-magnon states within the band of allowed energies $E$. The random distribution of coupling constants was assumed to have a

S. Drozdz, J. Kwapien, J. Speth, M. Wojcik

Complexity is an interdisciplinary concept which, first of all, addresses the question of how order emerges out of randomness. For many reasons matrices provide a very practical and powerful tool in approaching and quantifying the related characteristics. Based on several natural complex dynamical systems, like the strongly interacting quantum many-body syst

R. W. Hill, Cyril Proust, Louis Taillefer, P. Fournier

The behaviour of electrons in solids is remarkably well described by Landau's Fermi-liquid theory, which says that even though electrons in a metal interact they can still be treated as well-defined fermions, called ``quasiparticles''. At low temperature, the ability of quasiparticles to transport heat is strictly given by their ability to transp

Julienne M. Hill, David C. Johnston, Lance L. Miller

The reaction of Sr2CuO3 with air and liquid water was studied to address the origin of the reported variable Curie-Weiss impurity contribution to the magnetic susceptibility X of this compound at low temperatures. Sr2CuO3 was found to decompose upon exposure to either of these environments. The compound Sr2Cu(OH)6 was identified as the primary reaction produ

H. R. Schober

The motion of the structure determining components is highly collective, both in amorphous solids and in undercooled liquids. This has been deduced from experimental low temperature data in the tunneling regime as well as from the vanishing isotope effect in diffusion in glasses and undercooled liquids. In molecular dynamics simulations of glasses one observ

C. Tsallis, B. J. C. Cabral, A. Rapisarda, V. Latora

Schmidt et al (Phys Rev Lett 86, 1191 (2001)) observe and analyze a negative specific heat in Na clusters. The analysis is done within the framework of Boltzmann-Gibbs equilibrium statistical mechanics. We argue that this is not the only physical possibility to be taken into account. A possible connection with nonextensive statistical mechanics is considered

J. Sadowski, R. Mathieu, P. Svedlindh, M. Karlsteen

We have studied the magnetic properties of (GaMnAs)m/(GaAs)n superlattices with magnetic GaMnAs layers of thickness between 8 and 16 molecular layers (ML) (23-45 Å), and with nonmagnetic GaAs spacers from 4 ML to 10 ML (11-28 Å). While previous reports state that GaMnAs layers thinner than 50 Åare paramagnetic in the whole Mn composition range achievable usi

Henrique J. P. Freire, J. Carlos Egues

Here we investigate the spin-dependent subband structure of newly-developed Mn-based modulation-doped quantum wells. In the presence of an external magnetic field, the s-d exchange coupling between carriers and localized d electrons of the Mn impurities gives rise to large spin splittings resulting in a magnetic-field dependent subband structure. Within the

R. Mélin, Y. -C. Lin, P. Lajkó, H. Rieger

The effect of quenched disorder on the low-energy properties of various antiferromagnetic spin ladder models is studied by a numerical strong disorder renormalization group method and by density matrix renormalization. For strong enough disorder the originally gapped phases with finite topological or dimer order become gapless. In these quantum Griffiths pha

A. Serquis, R. Schulze, Y. T. Zhu, J. Y. Coulter

We studied the influence of sample preparation and defects in the superconducting properties samples using atomic ratios of Mg:B=1:1 and Mg:B=1:2. Samples were characterized by SEM, and XRD, and the magnetization properties were examined in a SQUID magnetometer. The presence of Mg vacancies was determined by Rietveld analysis. Most of the samples exhibited s

Dana I. Dinescu

Recent stellar populations and chemical abundance studies point to an accreted origin of omega Cen. In this light, and given the retrograde, small size orbit of omega Cen, we search for a kinematical signature left by bits hypothetical parent galaxy in the Solar neighborhood. We analyze the largets-to-date sample of metal poor stars (Beers et al. 2000) and w

Vahe' Petrosian, Timothy Q. Donaghy, James M. McTiernan

The discovery of hard X-ray sources near the top of a flaring loop by the HXT instrument on board the YOHKOH satellite represents a significant progress towards the understanding of the basic processes driving solar flares. In this paper we extend the previous study of limb flares by Masuda (1994) by including all YOHKOH observations up through August 1998.

E. Steinbring, D. Crampton, J. B. Hutchings

We have undertaken a program of high-resolution imaging of high-redshift radio galaxies (HzRGs) using adaptive optics on the Canada-France-Hawaii Telescope. We report on deep imaging in J, H,and K bands of 6 HzRGs in the redshift range 1.1 to 3.8. At these redshifts, near-infrared bandpasses sample the rest-frame visible galaxian light. The radio galaxy is r

M. O. Calvao, J. R. T. de Mello Neto, I. Waga

Redshift distortions, both geometrical and kinematical, of quasar clustering are simulated, for the Two-Degree Field QSO Redshift Survey (2QZ), showing that they are very effective to constrain the cosmological density and equation of state parameters, Omega_{m0}, Omega_{x0} and w. Particularly, it emerges that, for the cosmological constant case, the test i

R. C. Lamb, D. J. Macomb, T. A. Prince, W. A. Majid

We report the serendipitous detection of two previously unreported pulsars from the direction of the Small Magellanic Cloud, with periods of 16.6 and 25.5 seconds. The detections are based on archival PCA data from the Rossi X-ray Timing Explorer (RXTE). The observation leading to these detections occurred in September 2000 extending over 2.1 days with an ex

Nicholas G. Phillips, A. Kogut

We present a neural net algorithm for parameter estimation in the context of large cosmological data sets. Cosmological data sets present a particular challenge to pattern-recognition algorithms since the input patterns (galaxy redshift surveys, maps of cosmic microwave background anisotropy) are not fixed templates overlaid with random noise, but rather are

John P. Blakeslee

I summarize recent work comparing relative distances measured to individual galaxies with independent methods. The comparisons include: ground-based surface brightness fluctuation (SBF) and fundamental plane distances to 170 galaxies, distances predicted from galaxy velocities and the inferred gravity field, HST SBF measurements to seven early-type hosts of

Yves A. Gallant, Eric van der Swaluw, John G. Kirk, Abraham Achterberg

We review recent theoretical developments on pulsar winds, their nebulae and relativistic shock acceleration, and show how they illuminate unsolved problems in plerion spectra, in particular the multiple spectral breaks in the Crab and the low-frequency breaks of plerions such as G 21.5-0.9 and 3C 58. Recent work on Fermi acceleration theory at relativistic

John Heise, Jean in 't Zand

We discuss three classes of x-ray transients to highlight three new types of transients found with the Wide Field Cameras onboard BeppoSAX. First there are the transients related to Low Mass X-ray Binaries in outburst, typically lasting weeks to months and reaching luminosities of the Eddington limit for a few solar masses. Recently another subclass of outbu

Jeffrey D. Goldader, Gerhardt Meurer, Timothy M. Heckman, Mark Seibert

In an effort to better understand the UV properties of ultraluminous infrared galaxies (ULIGs), and compare them to the rest-frame UV properties of high redshift sub-mm and Lyman-break galaxies, we have obtained far- and near-UV imaging observations (lambda_{eff}=1457Å, lambda_{eff}=2364Å, respectively) of two luminous infrared galaxies (LIGs--VV 114 and IC

V. P. Reshetnikov, M. Faundez-Abans, M. de Oliveira-Abans

We present the results of B, V, R surface photometry of ESO603-G21 - a galaxy with a possible polar ring. The morphological and photometric features of this galaxy are discussed. The central round object of the galaxy is rather red and presents a nearly exponential surface brightness distribution. This central structure is surrounded by a blue warped ring or

Charles R. Keeton

By directly probing mass distributions, gravitational lensing offers several new tests of the CDM paradigm. Lens statistics place upper limits on the dark matter content of elliptical galaxies. Galaxies built from CDM mass distributions are too concentrated to satisfy these limits, so lensing extends the ``concentration problem'' in CDM to elliptical

V. Castellani, S. Degl'Innocenti, S. Petroni, G. Piotto

Taking advantage of recent HST data for field stars in the region of the Galactic globular cluster NGC 6397, we tested the predictions of several Galactic models with star counts reaching a largely unexplored range of magnitudes, down to $V$$\sim$ 26.5. After updating the input stellar ($V-I$) colors, we found that the two-component Bahcall-Soneira (B&S) mod

T. X. Thuan, Y. I. Izotov

By extrapolating to O/H = N/H = 0 the empirical correlations Y-O/H and Y-N/H defined by a relatively large sample of ~ 45 Blue Compact Dwarfs (BCDs), we have obtained a primordial 4Helium mass fraction Yp= 0.2443+/-0.0015 with dY/dZ = 2.4+/-1.0. This result is in excellent agreement with the average Yp= 0.2452+/-0.0015 determined in the two most metal-defici

D. Erspamer, P. North

This paper presents an automated method to determine detailed abundances for A and F-type stars. This method is applied on spectra taken with the ELODIE spectrograph. Since the standard reduction procedure of ELODIE is optimized to obtain accurate radial velocities but not abundances, we present a more appropriate reduction procedure based on IRAF. We descri

J. A. Rose, A. E. Gaba, W. A. Christiansen, D. S. Davis

Multi-fiber spectroscopy has been obtained for 335 galaxies in the field of the double cluster A3128/A3125, using the 2dF multi-fiber positioner on the AAT. A total of 532 objects in the double cluster now have known redshifts. We have also obtained a 20 ks Chandra ACIS-I image of A3128 and radio imaging with the MOST and the ATCA. The spatial-kinematic dist

Kazuyuki Omukai, Shu-ichiro Inutsuka

We analytically investigate the formation of an HII region in the accreting envelope of a newborn star. Special care is taken to examine the role of ionizing radiation force. This effect modifies velocity and density distributions and thereby affects the expansion of the HII region. As a result, the upper limit of the stellar mass imposed by the growth of an

Yael Fuchs

SS433 is a jet emitting X-ray binary surrounded by the W50 radio nebula. The SS433/W50 system is an excellent laboratory for studying relativistic jet interaction with the surrounding interstellar medium. In this context, part of the W50 nebula has been mapped with ISOCAM at 15 micron. I will show the results particularly on the W50 west lobe, and on 2 emitt

M. Bellazzini, F. Fusi Pecci, M. Messineo, L. Monaco

We present the first results of a deep WFPC2 photometric survey of the loose galactic globular cluster NGC 288. The fraction of binary systems is estimated from the color distribution of objects near the Main Sequence (MS) with a method analogous to that introduced by Rubenstein & Bailyn(1997). We have unequivocally detected a significant population of binar

Niruj R. Mohan, A. Cimatti, H. J. A. Roettgering, P. Andreani

We present the results of sub-mm, mm (850 um, 450 um and 1250 um) and radio (1.4 and 4.8 GHz) continuum observations of a sample of 27 K-selected Extremely Red Objects, or EROs, (14 of which form a complete sample with K < 20 and I-K > 5) aimed at detecting dusty starbursts, deriving the fraction of UltraLuminous Infrared Galaxies (ULIGs) in ERO samples, and

Matt J. Jarvis, Steve Rawlings, Steve Eales, Katherine M. Blundell

Using a new radio sample, 6C* designed to find radio galaxies at z > 4 along with the complete 3CRR and 6CE sample we extend the radio galaxy K-z relation to z~4.5. The 6C* K-z data significantly improve delineation of the K-z relation for radio galaxies at high redshift (z >2). In a spatially flat universe with a cosmological constant (Omega_M=0.3 and Omega

Christofer Gunnarsson

We investigate the effect of gravitational lensing on the farthest known supernova, SN1997ff. The SN was found at z~1.7 in the Hubble Deep Field North and is most likely of Type Ia. Due to our poor knowledge of the properties of the lensing foreground galaxies, we conclude that large magnification effects are possible for reasonable lens parameter values imp

Yael Fuchs, Lydie Koch-Miramond, Peter Abraham

We present ISOPHOT spectrophotometric observations of SS433 at four different orbital phases in 1996 and 1997. The HeI+HeII lines in both spectra of SS433 and the Wolf-Rayet star WR147, a WN8+BO5 binary system, closely match. The 2.5-12 micron continuum radiation is due to an expanding wind free-free emission in an intermediate case between optically thick a

Giovanni Vladilo

An analytical expression is presented that allows gas-to-dust elemental depletions to be estimated in interstellar environments of different types, including Damped Ly alpha systems, by scaling an arbitrary depletion pattern chosen as a reference. As an improvement on previous work, the scaling relation allows the dust chemical composition to vary and includ

T. W. Berghoefer, S. Bowyer

Kaastra et al. (1999) have used the BeppoSAX LECS instrument to search for excess EUV emission in Abell 2199. They claim that the results obtained confirm an independent report of an excess EUV emission in this cluster (Lieu et al. 1999). Using an inflight derived procedure that is better suited to the analysis of extended sources and which avoids uncertaint

Joel R. Primack

This article summarizes the possible roles of neutrinos in cosmology, from the first three minutes onward. The fact that primordial neutrinos are about as numerous as the photons of the cosmological background radiation means that neutrino (or ``hot&#39;&#39;) dark matter can have a significant impact upon how matter is distributed in the universe. Over the

S. K. Leggett, Peter H. Hauschildt, F. Allard, T. R. Geballe

We present 0.9-2.5um spectroscopy with R~800 and 1.12-1.22um spectroscopy with R~5800 for the M dwarfs Gl 229A and LHS 102A, and for the L dwarf LHS 102B. We also report IZJHKL&#39; photometry for both components of the LHS 102 system, and L&#39; photometry for Gl 229A. The data are combined with previously published spectroscopy and photometry to produce fl

P. S. Smith, G. D. Schmidt, D. C. Hines, R. M. Cutri

Optical broad-band polarimetry is presented for near-infrared color-selected AGN classified QSOs based on their K-band luminosity. More than 10% of a sample of 70 QSOs discovered in the Two Micron All Sky Survey (2MASS) with J-K > 2 and M_K < -23 show high broad-band linear polarization (P > 3%), and values range to a maximum of P = 11%. High polarization te

F. Reale, F. Bocchino, G. Peres

Long-lasting, intense, stellar X-ray flares may approach conditions of breaking magnetic confinement and evolving in open space. We explore this hypothesis with hydrodynamic simulations of flares occurring in a non-confined corona: model flares are triggered by a transient impulsive heating injected in a plane-parallel stratified corona. The plasma evolution

Joel R. Primack

Cold Dark Matter (CDM) has become the standard modern theory of cosmological structure formation. Its predictions appear to be in good agreement with data on large scales, and it naturally accounts for many properties of galaxies. But despite its many successes, there has been concern about CDM on small scales because of the possible contradiction between th

Gregory A. Fiete, Gergely Zarand, Bertrand I. Halperin, Yuval Oreg

Motivated by recent scanning tunneling microscope (STM) experiments on cobalt clusters adsorbed on single wall metallic nanotubes [Odom {\em et al.}, Science {\bf 290}, 1549 (2000)], we study theoretically the size dependence of STM spectra and spin-flip scattering of electrons from finite size ferromagnetic clusters adsorbed on metallic surfaces. We study t

Andrew E. Dolphin

A comprehensive study of the measurement of star formation histories from colour-magnitude diagrams (CMDs) is presented, with an emphasis on a variety of subtle issues involved in the generation of model CMDs and maximum likelihood solution. Among these are the need for a complete sampling of the synthetic CMD, the use of of proper statistics for dealing wit

E. V. Shuryak

We discuss simple generic model of ``jet quenching&#39;&#39; in which matter absorption is defined by one parameter. We show that as absorption grows, the azimuthal asymmetry v_2 grows as well, reaching the finite limit with a simple geometric interpretation. It turns out, that this limit is still below the experimental values for 6 > p_t > 2 GeV, according

Massimo Bianchi, Daniel Z. Freedman, Kostas Skenderis

We systematically develop the procedure of holographic renormalization for RG flows dual to asymptotically AdS domain walls. All divergences of the on-shell bulk action can be cancelled by adding covariant local boundary counterterms determined by the near-boundary behavior of bulk fields. This procedure defines a renormalized action from which correlation f

P. H. Damgaard, M. C. Diamantini, P. Hernandez, K. Jansen

Using quenched chiral perturbation theory we compute meson correlation functions at finite volume and fixed gauge field topology. We also present the corresponding analytical predictions for the unquenched theory at fixed gauge field topology. These results can be used to measure the low-energy parameters of the chiral Langrangian from lattice simulations in

Z. Chacko, Eduardo Ponton

We consider models which are natural extensions of those where supersymmetry is broken at low energy scales and transmitted to visible matter by gauge interactions. We investigate the situation where the quark and lepton superfields of the MSSM are localized to a brane in a higher dimensional space while the messenger fields and the sector which breaks super

Andreas Brandhuber

We construct several new G(2) holonomy metrics that play an important role in recent studies of geometrical transitions in compactifications of M-theory to four dimensions. In type IIA string theory these metrics correspond to D6 branes wrapped on the three-cycle of the deformed conifold and the resolved conifold with two-form RR flux on the blown-up two-sph

S. Skadhauge

We investigate the recently suggested scheme of independent mass matrices for neutrinos and antineutrinos. Such a CPT violating scheme is able to account for all neutrino data with the three known flavors. For atmospheric neutrinos this means that it is possible to have different mass squared differences driving the oscillation for neutrinos and antineutrino

Marco Frasca

We analyze the unitary time evolution of a conduction electron, described by a two-level system, interacting with two-level systems (spins) through a spin-spin interaction and prove that coherent spin states of the conduction electron are obtained in the strong coupling regime, when the number of the spins is taken to be, formally, infinitely large (thermody

Andrea Brignole, Giuseppe Degrassi, Pietro Slavich, Fabio Zwirner

We compute the O(alpha_t^2) two-loop corrections to the neutral CP-even Higgs boson mass matrix in the Minimal Supersymmetric Standard Model, for arbitrary values of mA and of the parameters in the stop sector, in the effective potential approach. In a large region of parameter space these corrections are sizeable, increasing the prediction for mh by several

Shinji Mukohyama, Lev Kofman

Four dimensional gravity in the low energy limit of a higher dimensional theory has been expected to be a (generalized) Brans-Dicke theory. A subtle point in brane world scenarios is that the system of four dimensional effective gravitational equations is not closed due to bulk gravitational waves and bulk scalars. Nonetheless, weak gravity on the brane can

David Polarski

General expressions are given for the generation of Primordial Black Holes (PBH) in a universe with a presently accelerated expansion due to a(n effective) cosmological constant. We give expressions both for a powerlaw scalefree primordial spectrum and for spectra which are not of that type. Specializing to the case of a pure cosmological constant $Λ$ and as

Ilia A. Solov&#39;yov, Andrey V. Solov&#39;yov, Walter Greiner

We have investigated structure and properties of small metal clusters using all-electron ab initio theoretical methods based on the Hartree-Fock approximation and density functional theory, perturbation theory and compared results of our calculations with the available experimental data and the results of other theoretical works. We have systematically calcu

M. D. Tonasse

We consider the problem of the ordinary charged fermion mass patterns in the framework of a version of the 3-3-1 electroweak gauge model, which includes charged heavy leptons. The masses of the top and the bottom quarks are given at the tree level. All the other charged fermions get their masses at the one loop level. The Yukawa coupling strength can be univ

Marcus Bleicher, Stefan Hofmann, Sabine Hossenfelder, Horst Stöcker

The production of black holes in large extra dimensions is studied for Tevatron energies. We find that black holes may have already been created in small abundance in $\bar p p$ collisions at $\sqrt s=1.8$ TeV. For the next Tevatron run ($\sqrt s=2.0$ TeV) large production rates for black holes are predicted.

S. Krivenko, A. Yaresko, G. Khaliullin, H. Fehske

We present a theory for spin excitations in ferromagnetic metallic manganites and demonstrate that orbital fluctuations have strong effects on the magnon dynamics in the case these compounds are close to a transition to an orbital ordered state. In particular we show that the scattering of the spin excitations by low-lying orbital modes with cubic symmetry c