September 2001 arXiv papers — page 9

Darren Creutz, C. E. Silva

We prove that a rank one transformation satisfying a condition called restricted growth is a mixing transformation if and only if the spacer sequence for the transformation is uniformly ergodic. Uniform ergodicity is a generalization of the notion of ergodicity for sequences in the sense that the mean ergodic theorem holds for what we call dynamical sequence

Oliver Johnson

We adapt arguments concerning entropy-theoretic convergence from the independent case to the case of FKG random variables. FKG systems are chosen since their dependence structure is controlled through covariance alone, though in the sequel we use many of the same arguments for weakly dependent random variables. As in previous work of Barron and Johnson, we c

Tony Shaska

In this paper we study genus 2 function fields K with degree 3 elliptic subfields. We show that the number of Aut(K)-classes of such subfields of K is 0,1,2, or 4. Also we compute an equation for the locus of such K in the moduli space of genus 2 curves.

Juan B. Gil, Paul A. Loya

Given a cone pseudodifferential operator $P$ we give a full asymptotic expansion as $t\to 0^+$ of the trace $\Tr Pe^{-tA}$, where $A$ is an elliptic cone differential operator for which the resolvent exists on a suitable region of the complex plane. Our expansion contains $\log t$ and new $(\log t)^2$ terms whose coefficients are given explicitly by means of

Harold Widom

In recent work of Baik, Deift and Rains convergence of moments was established for the limiting joint distribution of the lengths of the first k rows in random Young tableaux. The main difficulty was obtaining a good estimate for the tail of the distribution and this was accomplished through a highly nontrival Riemann-Hilbert analysis. Here we give a simpler

Ryushi Goto

We shall construct a moduli space of pairs of Kähler-Einstein structures and special lagrangians and obtain smoothness of the moduli space of these pairs. Further we show that the moduli space of these pairs is locally embedded in a certain relative cohomology group.

Christian Wolf

For a hyperbolic polynomial automorphism of $\C^2$, we show the existence of a measure of maximal dimension, and identify the conditions under which a measure of full dimension exists.

Michael Kunzinger, Roland Steinbauer

Co lombeau's construction of generalized functions (in its special variant) is extended to a theory of generalized sections of vector bundles. As particular cases, generalized tensor analysis and exterior algebra are studied. A point value characterization for generalized functions on manifolds is derived, several algebraic characterizations of spaces of

Joseph Polchinski, Matthew J. Strassler

We consider high-energy fixed-angle scattering of glueballs in confining gauge theories that have supergravity duals. Although the effective description is in terms of the scattering of strings, we find that the amplitudes are hard (power law). This is a consequence of the warped geometry of the dual theory, which has the effect that in an inertial frame the

Jose Figueroa-O'Farrill

This is the written version of the supersymmetry lectures delivered at the 30th and 31st British Universities Summer Schools in Theoretical Elementary Particle Physics (BUSSTEPP) held in Oxford in September 2000 and in Manchester in August-September 2001.

Tamas Hauer, Morten Krogh

We study IIB string theory on the orbifold R^8/Gamma with discrete torsion where Gamma is an arbitrary subgroup of U(4). We extend some previously known identities for discrete torsion in abelian groups to nonabelian groups. We construct explicit formulas for a large class of fractional D-brane states and prove that the physical states are classified by proj

Guy D. Moore

Recently Garcia Bellido et. al. have proposed that electroweak baryogenesis may occur at the end of inflation, in a scenario where the reheat temperature is too low for electroweak symmetry restoration. I show why the scenario is difficult to test reliably by classical field techniques on the lattice.

Stanley J. Brodsky

The diffractive dissociation of a hadron at high energies, by either Coulomb or Pomeron exchange, has a natural description in QCD as the materialization of the projectile's light-cone wavefunctions; in particular, the diffractive dissociation of a meson, baryon, or photon into high transverse momentum jets measures the shape and other features of the pr

P. M. Stevenson

The Higgs vacuum is a kind of medium. In any medium one generally expects sound waves for sufficiently long wavelengths (>> mean free path). I briefly describe how the broken-symmetry vacuum can be viewed as a Bose-Einstein condensate of `phion' particles. This picture yields a natural notion of the `mean free path'. I speculate that this is at the m

A. Pankov, N. Paver

We discuss electron-electron contact-interaction searches in the process e^+e^- -->e^+e^- at a future e^+e^- Linear Collider with c.m. energy \sqrt{s}=0.5 TeV and with both beams longitudinally polarized. Our analysis is based on the measurement of the polarized differential cross sections, and allows to simultaneously take into account the general set of co

G. Sigl

Cosmic high energy neutrinos are inextricably linked to the origin of cosmic rays which is one of the major unresolved questions in astrophysics. In particular, the highest energy cosmic rays observed possess macroscopic energies and their origin is likely to be associated with the most energetic processes in the Universe. Their existence triggered a flurry

J. O. Eeg, A. Hiorth, A. D. Polosa

We present a calculation of the process B --> D eta' within a heavy-light chiral quark model. We assume that the eta' has a large gluonic component, and its coupling is described via the glue-glue-eta' effective vertex. The main contribution comes from the non-factorizable part of the effective weak Lagrangian at quark level. We find, within our

S. M. Bilenky, T. Lachenmaier, W. Potzel, F. von Feilitzsch

Using the recent result of the SNO solar neutrino experiment, we have demonstrated in a model independent way that the contribution of Be-7 and other medium energy neutrinos to the event rate of the Homestake experiment is 4 sigma smaller than the BP2000 SSM prediction. We have considered the implications of this result for the future BOREXINO experiment.

G. Bonvicini, E. Cheu, J. Dolbeau, P. Gorodetzki

This paper will discuss the physics reach of a solar neutrino TPC containing many tons of He4 under high pressure. Particular attention is given to the LMA and SMA solutions, which are allowed by current data, and which are characterized by a lack of time-dependent phenomena (either summer-winter or day-night asymmetries). In this case, the physics of neutri

Ivan Vitev, Miklos Gyulassy, Peter Levai

Preliminary PHENIX data on $Au+Au$ reactions at $\sqrt{s}= 130$ AGeV suggest that $\bar{p}$ yields may exceed $π^-$ at high $p_{\rm T} > 2$ GeV/c. We propose that jet quenching in central collisions suppresses the hard PQCD component of the spectra in central $A+A$ reactions, thereby exposing a novel non-perturbative component of baryon dynamics. We suggest

Andrzej J. Buras

We review the main aspects of Flavour Physics and CP Violation in the Standard Model. After presenting a grand view of the field including a Master Formula for weak decays we discuss i) Standard analysis of the unitarity triangle, ii) The ratio epsilon'/epsilon, iii) Rare decays K^+ -> pi^+ nu barnu and K_L -> pi^0 nu barnu, iv) CP violation in B decays

V. Gogohia

We propose how to explicitly introduce the Jaffe-Witten mass gap into the quantum Yang-Mills theory. Through the full gluon propagator it is defined as such nonperturbative scale that when it formally goes to zero, then the perturbative phase survives in the theory only. The close link between mass gap and strong infrared singularities which are due to domin

F. A. Berends, R. van Gulik

In this paper a Monte Carlo generator, GaGaRes, is presented which can be used to describe two-photon resonance production in e^+e^- collisions. The program can generate the five lowest-lying C=+1 meson states of any q\bar{q} combination together with the outgoing electron and positron. The dependence on the photon virtualities Q_1^2 and Q_2^2 is fully taken

P. Taxil, J. -M. Virey

Concerning new physics beyond the Standard Model we explore the discovery and analysis potentials of polarized (hadronic) experiments and we compare with the unpolarized case. For discovery, beam polarization is helpful in the case of purely hadronic new interactions. In any case, beam polarization provides us a unique piece of information on the chiral and

Jun Tabei, Hiroshi Hotta

Several parameters of the minimal supergravity model are estimated by the method of the renormalization group. In this model, five arbitrary parameters $(m_0, m_{1/2}, \tanβ, A_0, {sig}(μ))$ are contained. $\tanβ$ is evaluated as 7.5 by the likelihood analysis of the gauge and Yukawa coupling constants. Further, the trilinear coupling constant $A_0$ is fixed

V. A. Nikolaev, O. G. Tkachev

In this talk we try to clarify the problems existing on the way of theorist decided to construct nuclear theory on the generalized Skyrme model background. We conclude that to construct such a model of light nuclei one have to construct a hybrid model where one particle degrees of freedom are concentrated around the surface of the nuclei and soliton with non

C. Hanhart, A. Sibirtsev, J. Speth

We reinvestigate the experimental data on $ω$--meson production in pion-nucleon collisions based on both an analytical approach and a Monte Carlo simulation. Our analysis allows us to study the kinematical peculiarities of the $π^-p{\to}ω{n}$ reaction at energies close to threshold. Based on the hypothesis, that the formalism derived in ref. [1] was applied

R. V. Gavai, Sourendu Gupta, R. Lacaze

We study quenched QCD just above the phase transition temperature using overlap Fermions. Exact zero modes of the overlap operator are localized. Chiral symmetry is restored, as indicated by the behavior of the chiral condensate after subtracting the effects of zero modes. The vector and pseudo-scalar screening masses are close to ideal gas values.

A. Di Giacomo, G. Paffuti

The existing evidence for dual superconductivity as mechanism of color confinement is reviewed. We also discuss what is known on the dual excitations, which produce confinement by condensation, and what are the open problems

KATRIN collaboration

With the compelling evidence for massive neutrinos from recent neutrino-oscillation experiments, one of the most fundamental tasks of particle physics over the next years will be the determination of the absolute mass scale of neutrinos. The absolute value of neutrino-masses will have crucial implications for cosmology, astrophysics and particle physics. We

G. Bonvicini, D. Naples, V. Paolone

In this note the issues surrounding the realization of a solar neutrino TPC are reviewed. The technical challenges can be summarized as building a very large TPC within the low background constraints of solar neutrino experimentation.

V. A. De Lorenci, E. S. Moreira

We derive the gravitational and electrostatic self-energies of a particle at rest in the background of a cosmic dispiration (topological defect), finding that the particle may experience potential steps, well potentials or potential barriers depending on the nature of the interaction and also on certain properties of the defect. The results may turn out to b

Hokyu Lee, Harmeet Sawhney

In the pre-divestiture era, the regulatory environment in the U.S. was fairly uniform and harmonious with the FCC setting the course and the accommodative state PUCs making corresponding changes in their own policies. The divestiture fractured this monolithic system as it forced the PUCs to respond to new forces unleashed in their own backyards. Soon there w

Z. L. Xiao, E. Y. Andrei, Y. Paltiel, E. Zeldov

By comparing the voltage-current (V-I) curves obtained before and after cutting a sample of 2H-NbSe2, we separate the bulk and edge contributions to the transport current at various dissipation levels and derive their respective V- I curves and critical currents. We find that the edge contribution is thermally activated across a current dependent surface bar

Alexander L. Fetter

A dense vortex lattice in a rotating dilute Bose-Einstein condensate is studied with the Thomas-Fermi approximation. The upper critical angular velocity Omega_{c2} occurs when the intervortex separation b becomes comparable with the vortex core radius xi. For a radial harmonic trap, the loss of confinement as Omega approaches omega_perp implies a singular be

J. M. P. van den Oever, F. A. M. Leermakers, G. J. Fleer, V. A. Ivanov

The coil-globule transition has been studied for A-B copolymer chains both by means of lattice Monte Carlo simulations using bond fluctuation algorithm and by a numerical self-consistent field method. Copolymer chains of fixed length with A and B monomeric units with regular, random and specially designed (protein-like) primary sequences have been investigat

Weiping Zhang, Han Pu, Chris Search, Pierre Meystre

The spin dynamics of atomic Bose-Einstein condensates confined in a one-dimensional optical lattice is studied. The condensates at each lattice site behave like spin magnets that can interact with each other through both the light-induced dipole-dipole interaction and the static magnetic dipole-dipole interaction. We show how these site-to-site dipolar inter

T. G. Rappoport, A. Saguia, B. Boechat, M. A. Continentino

A zero temperature real space renormalization group (RG) approach is used to investigate the role of disorder near the quantum critical point (QCP) of a Kondo necklace (XY-KN) model. In the pure case this approach yields $J_{c}=0$ implying that any coupling $J \not = 0 $ between the local moments and the conduction electrons leads to a non-magnetic phase. We

Yong Zhang, Miles Blencowe

We investigate the intrinsic noise of a micro-mechanical displacement detector based on the radio-frequency single-electron transistor (rf-SET). Using the noise analysis of a SET by Korotkov as our starting point, we determine the spectral density of the displacement noise due to the tunneling current shot noise. The resulting mechanical displacement noise d

A. Corcos, J. -P. Eckmann, A. Malaspinas, Y. Malevergne

Imitative and contrarian behaviors are the two typical opposite attitudes of investors in stock markets. We introduce a simple model to investigate their interplay in a stock market where agents can take only two states, bullish or bearish. Each bullish (bearish) agent polls m "friends'' and changes her opinion to bearish (bullish) if there is (1

C. M. Varma

Superfluid helium, describable by a two-component order parameter, exhibits only the Bogolubov mode with energy $\to 0$ at long wavelengths, while a Lorentz-invariant theory with a two-component order parameter exhibits a finite energy mode at long wavelengths (the Higgs Boson), besides the above mass-less mode. The mass-less mode moves to high energies if i

V. M. Krasnov

Operation of a Superconducting Quantum Interference Device (SQUID) made of stacked Josephson junctions is analyzed numerically for a variety of junction parameters. Due to a magnetic coupling of junctions in the stack, such a SQUID has certain advantages as compared to an uncoupled multi-junction SQUID. Namely, metastability of current-flux modulation can be

Keshav N. Shrivastava

We show that illumination by continuous white radiation saturates the population of levels so that some of the transitions are not observed. This reduces the number of observable transitions so that the resolution of transitions is improved. In the case of ν= 11/2 the improved resolution leads to clear observation of zero in the transverse resistivity which

G. B. Martins, J. C. Xavier, L. Arrachea, E. Dagotto

Numerical calculations illustrate the effect of the sign of the next nearest-neighbor hopping term t&#39; on the 2-hole properties of the t-t&#39;-J model. Working mainly on 2-leg ladders, in the -1.0 < t&#39;/t < 1.0 regime, it is shown that introducing t&#39; in the t-J model is equivalent to effectively renormalizing J, namely t&#39; negative (positive) i

A. Lascialfari, T. Mishonov, A. Rigamonti, P. Tedesco

The fluctuating diamagnetic magnetization Mfl at constant field H as a function of temperature and the isothermal magnetization Mfl vs H are measured in MgB2, above the superconducting transition temperature. The expressions for Mfl in randomly oriented powders are derived in the Gaussian approximation of local Ginzburg-Landau theory and used for the analysi

V. N. Naumov, G. I. Frolova, V. V. Nogteva, A. I. Romanenko

The temperature dependence of heat capacity for the samples of 90 K phase of YBa_2Cu_3O_{6+x} with x = 0.85, 0.90 and 0.95 was investigated above T_c. For separating the heat capacity into regular and anomalous contributions the special technique was used. For all the samples the anomalies in intervals 100-200 K (T_{low}), 205-230 K (T_m) and 260-290 K (T_h)

D. Sprinzak, Yang Ji, M. Heiblum, D. Mahalu

We report here on a direct and non-invasive measurement of the charge and its distribution in a Kondo correlated quantum dot (QD). A non-invasive potential-sensitive detector in proximity with the QD reveals that even though the conductance of the QD is significantly enhanced as it enters the Kondo regime the net charge in the QD remains unaffected. This dem

Watson Kuo, C. D. Chen

We theoretically investigate spin dependent transport in ferromagnetic/normal metal/ferromagnetic single electron transistors by applying master equation calculations using a two dimensional space of states involving spin and charge degrees of freedom. When the magnetizations of ferromagnetic leads are in anti-parallel alignment, the spins accumulate in the

M. Duran, E. del Barco, J. M. Hernandez, J. Tejada

Temperature-independent magnetic viscosity in ferritin has been observed from 2 K down to 100 mK, proving that quantum tunneling plays the main role in these particles at low temperature. Magnetic relaxation has also been studied using the Landau-Zener method making the system crossing zero resonant field at different rates, alpha=dH/dt, ranging from 10^{-5}

A. A. Zhukov, A. Purnell, Y. Miyoshi, Y. Bugoslavsky

The microwave power, dc magnetic field, frequency and temperature dependence of the surface resistance of MgB2 films and powder samples were studied. Sample quality is relatively easy to identify by a number of characteristics, the most clear being the breakdown in the omega squared law for poor quality samples. Analysis of the experimental data suggests the

Xiao Fan Wang

We show that two initially weakly coupled chaotic systems can achieve self-organized synchronization by adaptively reducing their speed and/or enhancing the coupling strength. Explicit adaptive algorithms for speed-reduction and coupling-enhancement are provided. We apply these algorithms to the self-organized synchronization of two coupled Lorenz systems. I

D. Sanchez-Portal, Richard M. Martin, S. M. Kauzlarich, W. E. Pickett

The ``14-1-11&#39;&#39; phase compounds based on magnetic Mn ions and typified by Ca14MnBi11 and Ba14MnBi11 show unusual magnetic behavior, but the large number (104) of atoms in the primitive cell has precluded any previous full electronic structure study. Using an efficient, local orbital based method within the local spin density approximation to study th

Y. Shibata, S. Nishimoto, Y. Ohta

We study the charge ordering (CO) in the one-dimensional (1D) extended Hubbard model at quarter filling where the nearest-neighbor Coulomb repulsion and dimerization in the hopping parameters are included. Using the cluster mean-field approximation to take into account the effect of quantum fluctuations, we determine the CO phase boundary of the model in the

Carsten Honerkamp, Manfred Salmhofer

We use a novel temperature-flow renormalization group technique to analyze magnetic and superconducting instabilities in the two-dimensional t-t&#39; Hubbard model for particle densities close to the van Hove filling as a function of the next-nearest neighbor hopping t&#39;. In the one-loop flow at the van Hove filling, the characteristic temperature for the

S. P. Pai, S. Wanchoo, S. C. Purandare, T. Banerjee

We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-d (YBCO). The heterojunctions were grown in situ by sequentially growing LCMO and YBCO films on <100> LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 microns width were

Hitoshi Seo, Masao Ogata, Hidetoshi Fukuyama

A new mechanism of the Verway transition in magnetite (Fe3O4), which has been argued to be a charge ordering transition so far, is proposed. Based on the mean field calculations for the three band model of spinless fermions appropriate for the d electrons of the Fe ions on the B sites, it is indicated that the phase transition should be the bond dimerization

M. H. S. Amin, A. N. Omelyanchouk, A. M. Zagoskin

A theory is offered for a novel device, mesoscopic four-terminal SQUID. The studied system consists of a mesoscopic four-terminal junction, one pair of terminals of which is incorporated in a superconducting ring and the other one is connected with a transport circuit. The nonlocal weak coupling between the terminals leads to effects of phase dragging and ma

Romeel Davé, Neal Katz, Lars Hernquist, David Weinberg

We investigate the X-ray vs. optical scaling relations of poor groups to small clusters (sigma~100-700 km/s) identified in a cosmological hydrodynamic simulation of a Lambda-CDM universe, with cooling and star formation but no pre-heating. We find that the scaling relations between X-ray luminosity, X-ray temperature, and velocity dispersion show significant

D. W. Hoard, S. Wachter, L. Lee Clark, Timothy P. Bowers

Because accretion-generated luminosity dominates the radiated energy of most cataclysmic variables, they have been ``traditionally&#39;&#39; observed primarily at short wavelengths. Infrared observations of cataclysmic variables contribute to the understanding of key system components that are expected to radiate at these wavelengths, such as the cool outer

S. M. Khairul Alam, James S. Bullock, David H. Weinberg

Using an analytic model calibrated against numerical simulations, we calculate the central densities of dark matter halos in a ``conventional&#39;&#39; cold dark matter model with a cosmological constant (LCDM) and in a ``tilted&#39;&#39; model (TLCDM) with slightly modified parameters motivated by recent analyses of Ly-alpha forest data. We also calculate h

G. Fabbiano

This talk discusses the growing impact of Chandra observations on the study of galaxies. In particular, we address progress in the study of X-ray source populations in diverse galaxies and in the study of the hot ISM.

Ian S. McLean, L. Prato, Sungsoo S. Kim, M. K. Wilcox

We report the possible identification of weak methane spectral features in the near-infrared K band in two late L dwarfs, DENIS 0205-11 (L7) and 2MASS 1523+30 (L8). New, high signal-to-noise ratio flux-calibrated spectra, spanning the wavelength interval 1.10 - 2.35 microns with an average resolving power R = 1800 were obtained using NIRSPEC on the Keck II t

T. Fang, D. S. Davis, J. C. Lee, H. L. Marshall

We present the high-resolution X-ray spectrum of the low-redshift quasar H 1821+643 and its surrounding hot cluster observed with the Chandra High Energy Transmission Grating Spectrometer (HETGS). An iron emission line attributed to the quasar at ~6.43 keV (rest frame) is clearly resolved, with an equivalent width of ~100 eV. Although we cannot rule out cont

Philipp Podsiadlowski, Saul Rappaport, Eric Pfahl

As has only recently been recognized, X-ray binaries with intermediate-mass secondaries are much more important than previously believed. To assess the relative importance of low- and intermediate-mass X-ray binaries (LMXBs and IMXBs), we have initiated a systematic study of these systems consisting of two parts: an exploration of the evolution of LMXBs and

F. Hammer, H. Flores

Star formation history shows a gradual decline since the last 8-9 Gyr (z=1). The bulk of present-day stellar mass and metal content was formed at redshifts lower than 2-3, which is consistent with a hierarchical scenario of galaxy formation. Observations of galaxy evolution during the last 2/3 of the Universe age could be done in great details, and provide n

Ruth A. Daly, Erick J. Guerra

FRIIb radio galaxies provide a tool to determine the coordinate distance to sources out to redshifts of two. The coordinate distance depends on the present values of global cosmological parameters, quintessence, and the equation of state of quintessence, and provides one of the cleanest determinations of global cosmological parameters because it does not dep

M. Vestergaard

A large, high-quality spectral data base of well-selected, moderate-redshift radio-loud and radio-quiet quasars is used to characterize the incidence of narrow associated CIV lambda 1549 absorption, and how this may depend on some quasar properties, including radio-type. Preliminary results of this study are presented.

K. Omukai, F. Palla

We investigate the formation by accretion of massive primordial protostars in the range 10 to 300 Msun. The high accretion rate used in the models (4.4 x 10^{-3} Msun/yr) causes the structure and evolution to differ significantly from those of both present-day protostars and primordial zero-age main sequence stars. After an initial expansion of the radius (f

J. C. Jackson

Based upon a simple vacuum Lagrangian, comprising cosmological and quadratic scalar field terms, a cosmological model is presented whose history is indistinguishable from that of an innocuous low-density cold dark matter (CDM) universe, but whose future is very much shorter. For sensible values of the deceleration parameter (0<q_0<1), its age is greater than

J. C. Jackson, Marina Dodgson

Recent observations suggest that Hubble's constant is large, and hence that the Universe appears to be younger than some of its constituents. The traditional escape route, which assumes that the expansion is accelerating, appears to be blocked by observations of Type 1a supernovae, which suggest(ed) that the Universe is decelerating. These observations are r

A. Raig, G. Gonzalez-Casado, E. Salvador-Sole

A modified version of the extended Press-Schechter model for the growth of dark-matter haloes was introduced in two previous papers with the aim at explaining the mass-density relation shown by haloes in high-resolution cosmological simulations. In this model major mergers are well separated from accretion, thereby allowing a natural definition of halo forma

Giovanni Carraro, Ferdinando Patat

In this paper we present and analyze CCD $UBVRI$ photometry in the region of the three young open clusters NGC 3114, Collinder~228, and vdB-Hagen~99,

B. Aschenbach

The performance of the three X-ray telescopes on-board of XMM-Newton is evaluated addressing imaging characteristics and effective collecting area. The agreement with ground calibration data is excellent. The analysis of images and spectra of cosmic X-ray sources, emphazising supernova and supernova remnants, prooves that the telescopes are even better than

V. Burwitz, V. E. Zavlin, R. Neuhaeuser, P. Predehl

We present the Chandra LETGS X-ray spectrum of the nearby (~60 pc) neutron star RX J1856.5-3754. Detailed spectral analysis of the combined X-ray and optical data rules out the nonmagnetic neutron star atmosphere models with hydrogen, helium, iron and solar compositions. We also conclude that strongly magnetized atmosphere models are unable to represent the

Valentina D&#39;Odorico, Patrick Petitjean, Stefano Cristiani

We present preliminary results of an investigation of the clustering properties of high matter density peaks between redshift ~2 and ~3, as traced by Lyman limit and Damped Ly-alpha systems in spectra of close QSO pairs and groups.

M. Boer, H. Pack, C. Pennypacker, A. L. Melchior

Hands-On Universe (HOU) is an educational program that enables students to investigate the Universe while applying tools and concepts from science, math, and technology. Using the Internet, HOU participants around the world request observations from an automated telescope, download images from a large image archive, and analyze them with the aid of user-frie

M. Boer, C. Thiebaut, A. Klotz, G. Buchholtz

The TAROT telescope has for primary goal the search for the prompt optical counterpart of Cosmic Gamma-Ray Bursts. It is a completely autonomous 25cm telescope installed near Nice (France), able to point any location of the sky within 1-2 seconds. The control, scheduling, and data processing activities are completely automated, so the instrument is completel

Tadashi Nakajima, Takashi Tsuji, Kenshi Yanagisawa

We have obtained near-infrared spectra of three L dwarfs discovered by 2MASS, 1506+13 (L3), 1507-16 (L5), and 0920+35 (L6.5). From the comparison of the H and K band spectra of these L dwarfs, we have found the presence of methane absorption in 0920+35. This implies that detectable methane absorption in the H and K bands, usually considered the signature of

Stephen E. Zepf

This paper reviews some recent work on the properties of the outer halos of galaxies. I particularly focus on recent and upcoming advances made with the study of globular clusters. Globular clusters can be observed out to ~100 kpc from the centers of galaxies, allowing the study of galactic halos well beyond the regions probed by many other techniques such a

Jasonjot Singh Kalirai, Paolo Ventura, Harvey B. Richer, Gregory G. Fahlman

We present deep CCD photometry of the very rich, intermediate aged (similar to the Hyades) open star cluster NGC 2099 (M37). The V, B-V color-magnitude diagram (CMD) for the cluster shows an extremely well populated and very tightly constrained main-sequence extending over 12 magnitudes from the turn-off. The CFH12K photometry for this cluster is faint enoug

Kenneth R. Sembach

Our view of the high velocity cloud (HVC) system is changing dramatically with new observations from the Far Ultraviolet Spectroscopic Explorer mission and the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. In particular, the detection of O VI absorption indicates that many HVCs have a hot, collisionally-ionized component in additio

Andrej Vilfan

We discuss a theoretical model for the cooperative binding dynamics of tropomyosin to actin filaments. Tropomyosin binds to actin by occupying seven consecutive monomers. The model includes a strong attraction between attached tropomyosin molecules. We start with an empty lattice and show that the binding goes through several stages. The first stage represen

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

We report on thermal noise from the internal friction of dielectric coatings made from alternating layers of Ta2O5 and SiO2 deposited on fused silica substrates. We present calculations of the thermal noise in gravitational wave interferometers due to optical coatings, when the material properties of the coating are different from those of the substrate and

Peter Gacs

Two infinite walks on the same finite graph are called compatible if it is possible to introduce delays into them in such a way that they never collide. Years ago, Peter Winkler asked the question: for which graphs are two independent walks compatible with positive probability. Up to now, no such graphs were found. We show in this paper that large complete g

Ricardo P. Schiavon, S. M. Faber, James A. Rose, Bruno V. Castilho

We develop a new set of models for intermediate-metallicity single stellar populations in the blue/optical region and use those models to determine the spectroscopic age of 47 Tuc. The models are based on a moderately high-resolution (1.8 A FWHM) empirical spectral library, state-of-the-art theoretical isochrones from M. Salaris and the most recent set from

Ricardo P. Schiavon, S. M. Faber, Bruno V. Castilho, James A. Rose

We perform an empirical synthesis of the blue integrated spectrum of the metal-rich globular cluster 47 Tucanae, based directly on the color-magnitude diagram of the cluster coupled to a moderately high-resolution spectral library. Freed from any significant dependence on theory, we are able to perform a fundamental test of the adequacy of the spectral libra

S. F. Tuan

The suggestion by Jaffe that if $σ$ is a light $q^{2}\bar{q}^{2}$ state $0^{++}$ then even the fundamental chiral transformation properties of the $σ$ becomes {\bf unclear}, has stimulated much interest. Adler pointed out that in fact the seminal work on chiral symmetry via PCAC consistency, is really quite consistent with the $σ$ being predominantly $q^{2}\

Peter M. Woods, Chryssa Kouveliotou, Ersin Gougus, Mark H. Finger

We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of ~4, which persist for several months. Using long baselin

Robert Brandenberger, Damien A. Easson, Dagny Kimberly

Brane Gas Cosmology (BGC) is an approach to M-theory cosmology in which the initial state of the Universe is taken to be small, dense and hot, with all fundamental degrees of freedom near thermal equilibrium. Such a starting point is in close analogy with the Standard Big Bang (SBB) model. The topology of the Universe is assumed to be toroidal in all nine sp

Fiona Hoyle, Michael S. Vogeley

We describe an algorithm to detect voids in galaxy redshift surveys. The method is based on the void finder algorithm of El-Ad & Piran. We apply a series of tests to determine how accurately we are able to recover the volumes of voids using our detection method. We simulate voids of different ellipticity and find that if voids are approximately spherical, ou

Elham Kashefi, Adrian Kent, Vlatko Vedral, Konrad Banaszek

A standard quantum oracle $S_f$ for a general function $f: Z_N \to Z_N $ is defined to act on two input states and return two outputs, with inputs $\ket{i}$ and $\ket{j}$ ($i,j \in Z_N $) returning outputs $\ket{i}$ and $\ket{j \oplus f(i)}$. However, if $f$ is known to be a one-to-one function, a simpler oracle, $M_f$, which returns $\ket{f(i)}$ given $\ket

Miklos Gyulassy, Ivan Vitev, Xin-Nian Wang, Pasi Huovinen

Rapid 3+1D transverse plus Bjorken collective expansion in $A+A$ collisions at ultra-relativistic energies is shown to reduce substantially the azimuthal asymmetry resulting from jet quenching. While the azimuthal asymmetry in non-central collisions, $v_2(p_T>2 \rm{GeV/c})\sim 0.15$ reported by STAR at RHIC, can be accounted for by spatially anisotropic jet

Boris Kastening, Hagen Kleinert, Bruno Van den Bossche

As a step towards deriving universal amplitude ratios of the superconductive phase transition we calculate the vacuum energy density in the symmetric phase of O(N)-symmetric scalar QED in D=4-epsilon dimensions in an epsilon-expansion using the minimal subtraction scheme commonly denoted by MS-bar. From the diverging parts of the diagrams, we obtain the reno

David H. Adams

The index bundle of the Overlap lattice Dirac operator over the orbit space of lattice gauge fields is introduced and studied. Obstructions to the vanishing of gauge anomalies in the Overlap formulation of lattice chiral gauge theory have a natural description in this context. Our main result is a formula for the topological charge (integrated Chern characte

Lee Lindblom, Joel E. Tohline, Michele Vallisneri

Nonlinear evolution of the gravitational radiation (GR) driven instability in the r-modes of neutron stars is studied by full numerical 3D hydrodynamical simulations. The growth of the r-mode instability is found to be limited by the formation of shocks and breaking waves when the dimensionless amplitude of the mode grows to about three in value. This maximu

M. Anselmino, D. Boer, U. D&#39;Alesio, F. Murgia

Following a previous description of Lambda and Lambda-bar polarization in unpolarized p-p interactions, within a perturbative QCD factorization scheme with new polarizing fragmentation functions, here we investigate the transverse polarization of Lambda&#39;s and Lambda-bar&#39;s produced in semi-inclusive DIS. Analytical expressions for both neutral and cha

Alain J. Brizard

The variational formulation for Lie-transform Hamiltonian perturbation theory is presented in terms of an action functional defined on a two-dimensional parameter space. A fundamental equation in Hamiltonian perturbation theory is shown to result from the freedom of choice of the integration path for the action functional.

R. S. Freitas, L. Ghivelder, P. Levy, F. Parisi

We present magnetization studies in a series of phase separated La$_{0.5}$Ca$%_{0.5}$MnO$_{3}$ samples, with different low temperature fractions of the ferromagnetic (FM) and charge ordered-antiferromagnetic (CO-AFM) phases. A particular experimental procedure probes the effect of the magnetic field applied while cooling the samples, which promotes FM fracti

Richard J. Szabo

A pedagogical and self-contained introduction to noncommutative quantum field theory is presented, with emphasis on those properties that are intimately tied to string theory and gravity. Topics covered include the Weyl-Wigner correspondence, noncommutative Feynman diagrams, UV/IR mixing, noncommutative Yang-Mills theory on infinite space and on the torus, M

Hiroyuki Kawamura, Jiro Kodaira, Cong-Feng Qiao, Kazuhiro Tanaka

We investigate the B meson light-cone distribution amplitudes in the heavy-quark limit which are relevant for the QCD factorization approach for the exclusive B meson decays. We derive exact relations between two- and three-particle distribution amplitudes from the QCD equations of motion and heavy-quark symmetry constraint. As solution of these relations, w