February 2001 arXiv papers — page 4

M. D. Sumption, X. Peng, E. Lee, M. Tomsic

Transport current values of 7.5 x 104 A/cm2 at 4.2 K and self-field are reported for MbB2-based tapes. MgB2 strands were formed by directly filling commercially available MgB2 powder into Nb-lined, monel tubes and wire drawing. The wires were then rolled into tapes 2.56 x 0.32 mm2, with a total superconducting cross section of 0.2319 mm2. Transport measureme

Philip D. Mannheim

With attempts to quench the cosmological constant $Λ$ having so far failed, we instead investigate what could be done if $Λ$ is not quenched and actually gets to be as big as elementary particle physics suggests. Since the quantity relevant to cosmology is actually $Ω_Λ$, quenching it to its small measured value is equally achievable by quenching not $Λ$ but

F. Nicastro, A. Fruscione, M. Elvis, A. Siemiginowska

Mkn 421 was observed by Chandra twice, on November 5, 1999 as part of the Chandra calibration program, with the ACIS-HETG configuration, and on May 29, 2000 following our Target Of Opportunity request aimed to catch the source in an ultra-high state, with both the ACIS-HETG and the HRC-LETG configurations. In this contribution we present and compare the two

Herman J. Mosquera Cuesta, Danays Morejon Gonzalez

Berezinsky, Hnatyk and Vilenkin showed that superconducting cosmic strings could be central engines for cosmological gamma-ray bursts and for producing the neutrino component of ultra-high energy cosmic rays. A consequence of this mechanism would be that a detectable cusp-triggered gravitational wave burst should be released simultaneously with the $γ$-ray s

L. M. Macri, D. D. Sasselov, K. Z. Stanek

We report on the remarkable evolution in the light curve of a variable star discovered by Hubble (1926) in M33 and classified by him as a Cepheid. Early in the 20th century, the variable, designated as V19, exhibited a 54.7 day period, an intensity-weighted mean B magnitude of 19.59+/-0.23 mag, and a B amplitude of 1.1 mag. Its position in the P-L plane was

Igor O. Drozdovsky, Regina E. Schulte-Ladbeck, Ulrich Hopp, Mary M. Crone

We find that NGC6789 is the most nearby example of a Blue Compact Dwarf galaxy known to date. With the help of WFPC2 aboard the Hubble Space Telescope, we resolve NGC6789 into over 15,000 point sources in the V and I bands. The young stars of NGC6789 are found exclusively near the center of the galaxy. The red giant population identified at large galacticent

Tsevi Mazeh, David W. Latham, Elad Goldberg, Guillermo Torres

We present a radial-velocity study of the triple-lined system Gliese 644 and derive spectroscopic elements for the inner and outer orbits with periods of 2.9655 and 627 days. We also utilize old visual data, as well as modern speckle and adaptive optics observations, to derive a new astrometric solution for the outer orbit. These two orbits together allow us

T. Shanks, P. D. Allen, F. Hoyle, N. R. Tanvir

We first discuss why there remains continuing, strong motivation to investigate Hubble's Constant. Then we review new evidence from an investigation of the Galactic Open Clusters containing Cepheids by Hoyle et al. that the metallicity dependence of the Cepheid P-L relation is stronger than expected. This result is supported by a new analysis of mainly H

J. P. Maier, N. M. Lakin, G. A. H. Walker, D. A. Bohlender

The smallest polyatomic carbon chain, C$_{3}$, has been identified in interstellar clouds (A$_{v}\sim$1 mag) towards $ζ$ Ophiuchi, 20 Aquilae, and $ζ$ Persei by detection of the origin band in its $A^{1}Π_{u}-X^{1}Σ^{+}_{g}$ electronic transition, near 4052Å. Individual rotational lines were resolved up to $J$=30 enabling the rotational level column densitie

Tassilo Ott

Adiabatic perturbations in the cosmology of a quintessential scalar field with exponential potential gravitationally coupled to radiation/matter are investigated in a gauge invariant formalism. The main question addressed in this paper is if the inhomogenous fluctuations can be ignored as often argued and the result is that this is not always the case. Conse

Paul D. Allen, Tom Shanks

Using published HST Cepheid data from 25 galaxies, we have found a correlation between the P-L dispersion and host galaxy metallicity which is significant at the ~3sigma level in the V band. This result supports the suggestion that the metallicity dependence of the Cepheid P-L relation may be stronger than expected. The high observed dispersions in the HST C

John M. Carpenter, Lynne A. Hillenbrand, M. F. Skrutskie

We present an analysis of J, H, and K time series photometry obtained with the southern 2MASS telescope over a 0.84 x 6 deg^2 region centered near the Orion Nebula Cluster. These data are used to establish the near-infrared variability properties of pre-main-sequence stars in Orion on time scales of 1-36 days, 2 months, and 2 years. A total of 1235 variable

Eric Perlman, William Sparks, John Biretta, Duccio Macchetto

We summarize HST observations of the M87 jet, concentrating on polarimetry and spectral index maps, and compare its optical and radio structures. The evidence now supports a stratified model for the structure of the jet, whereby high-energy, optical synchrotron emitting particles occupy physically different regions of the jet, closer to the jet axis, with di

Knut A. G. Olsen, Sungeun Kim, Jeremy F. Buss

Stellar spectroscopy, UBV photometry, H$α$ imaging, and analysis of data from the ATCA \ion{H}{1} survey of the LMC are combined in a study of the LMC OB association LH 72 and its surroundings. LH 72 lies on the rim of a previously identified \ion{H}{1} shell, SGS-14, and in the interior of LMC-4, one of the LMC's largest known supergiant shells. Our ana

T. Antoni

The experiment KASCADE observes simultaneously the electron-photon, muon, and hadron components of high-energy extensive air showers (EAS). The analysis of EAS observables for an estimate of energy and mass of the primary particle invokes extensive Monte Carlo simulations of the EAS development for preparing reference patterns. The present studies utilize th

Zheng Zheng, Chris Flynn, Andrew Gould, John N. Bahcall

We study a sample of about 1400 disk M dwarfs that are found in 148 fields observed with the Wide Field Camera 2 (WFC2) on the Hubble Space Telescope and 162 fields observed with pre-repair Planetary Camera 1 (PC1), of which 95 of the WFC2 fields are newly analyzed. The method of maximum likelihood is applied to derive the luminosity function and the Galacti

Marina orio, Roberto Casalegno, Chris Conselice, Jochen Greiner

We report on initial progress in a program of optical identification of supersoft X-ray sources in M31, pursued mainly with the WIYN telescope. We propose the identification of one supersoft X-ray source with a variable star, which we believe to have been a classical or recurrent nova in outburst in September 1990. The nova remnant must have been still a sup

Marina Orio, Arvind Parmar

Nova Vel 1999 (V382 Vel) was observed with BeppoSAX twice, 15 days and 6 months after the optical maximum. A hard X-ray source was detected in the first observation, while the second time also a very luminous supersoft X-ray source was detected. The continuum observed in the supersoft range with the BeppoSAX LECS cannot be fitted with atmospheric models of h

P. Schuecker, H. Boehringer, K. Arzner, T. H. Reiprich

Gaussian stochastic diffusion processes are used to derive cosmic mass functions. To get analytic relations previous studies exploited the sharp $k$-space filter assumption yielding zero drift terms in the corresponding Fokker-Planck (Kolmogorov's forward) equation and thus simplifying analytic treatments significantly (excursion set formalism). In the p

F. Fiore, S. Pellegrini, G. Matt, L. A. Antonelli

BeppoSAX observed NGC4258 on December 1998, when its 2-10 keV luminosity was \~1E41 erg/s. 100% variability is observed in the 3-10 keV band on timescales of a half a day while 20% variability is observed on timescales of one hour. The nuclear component is visible above 2 keV only, being obscured by a column density of (9.5+/-1.2)E22 cm-2; this component is

M. Orio, A. Parmar, R. Benjamin, L. Amati

We present BeppoSAX observations of Nova Velorum 1999 (V382 Vel), done in a broad X-ray band covering 0.1-300 keV only 15 days after the discovery and again after 6 months. The nova was detected at day 15 with the BeppoSAX instruments in the energy range 1.8-10 keV and we attribute the emission to shocks in the ejecta. The plasma temperature was kT~6 keV and

Chenggang Shu, Shude Mao, H. J. Mo

We use the observed sizes and star formation rates of Lyman-break galaxies (LBGs) to understand their properties expected in the hierarchical scenario of galaxy formation. The observed size distribution constrains the masses of the host haloes of LBGs from below, while the observed star-formation distribution constrains the masses from above. Assuming a flat

P. W. Gorham, K. M. Liewer, C. J. Naudet, D. P. Saltzberg

We report on results from about 30 hours of livetime with the Goldstone Lunar Ultra-high energy neutrino Experiment (GLUE). The experiment searches for <10 ns microwave pulses from the lunar regolith, appearing in coincidence at two large radio telescopes separated by about 22 km and linked by optical fiber. The pulses can arise from subsurface electromagnet

S. Boissier, N. Prantzos

We explore the implications for the high redshift universe of ``state-of-the-art&#39;&#39; models for the chemical and spectrophotometric evolution of spiral galaxies. The models are based on simple ``scaling relations&#39;&#39; for discs, obtained in the framework of Cold Dark Matter models for galaxy formation, and were ``calibrated&#39;&#39; as to reprodu

Pavel Naselsky, Jens Schmalzing, Jesper Sommer-Larsen, Steen Hannested

We point out that polarization measurements as planned for the upcoming PLANCK mission can significantly enhance the accuracy of cosmic parameter estimation compared to the temperature anisotropy spectrum alone. In order to illustrate this, we consider a standard cosmological model and several modifications that adjust one parameter each to fit the recently

Daniel Kabat, Arvind Rajaraman

Banks has proposed a relation between the scale of supersymmetry breaking and the cosmological constant in de Sitter space. His proposal has a natural extension to a general FRW cosmology, in which the supersymmetry breaking scale is related to the Hubble parameter. We study one consequence of such a relation, namely that coupling constants change as the uni

Koji Hashimoto, Shinji Hirano

In a tachyon model proposed by Minahan and Zwiebach and derived in the boundary string field theory, we construct various new solutions which correspond to nontrivial brane configurations in string theory. Our solutions include Dp-D(p-2) bound states, (F, Dp) bound states, string junctions, D(p-2)-branes ending on a Dp-brane, D(p-2)-branes suspended between

Koji Hashimoto, Shinji Hirano

We explored a variety of brane configurations in our previous paper within the two derivative truncation of the unstable D9-brane effective theory. In this paper we extend our previous results with emphasis on the inclusion of the higher derivative corrections for the tachyon and the gauge fields computed in the boundary string field theories. We give the ex

Dumitru M. Ghilencea, Graham G. Ross

We estimate the significance of the prediction for the gauge couplings in the MSSM with an underlying unification. The correlation between the couplings covers only (0.2-2)% of the a priori reasonable region of the parameter space, while the prediction for $\sin ^{2}θ_{W}$ is accurate to 1.3%. Given that agreement with experiment to such precision is unlikel

O. V. Teryaev

The crossing properties of the matrix elements of non-local operators, parameterized by Generalized Parton Distribution, are considered. They are especially simple in terms of the Double Distributions which are common for the various kinematical regions. As a result, Double Distributions may be in principle extracted from the combined data in these regions b

Mei Huang, Pengfei Zhuang, Weiqin Chao

The mesonic quantum fluctuations and their corrections on the chiral condensate and pion polarization function are investigated in the self-consistent scheme of SU(2) Nambu-Jona-Lasinio model by exactly calculating the next-to-leading order (NLO) Feynman diagrams in $1/N_c$ expansion. While the fluctuations and corrections depend strongly on the meson&#39;s

V. V. Gvaramadze

It is generally accepted that the PSR B1509-58 is associated with the supernova remnant (SNR) MSH 15-52 (G 320.4-01.2). The spin-down age of the pulsar is \simeq 1700 years, while the size and the general appearance of the SNR suggest that this system is much older. A few possible explanations of this discrepancy have been put forward. We offer an alternativ

A. Basu, S. D. Joglekar

We study the non-local regularization for the case of a spontaneously broken abelian gauge theory in the R_xi gauge with an arbitrary gauge parameter xi. We consider a simple abelian-Higgs model with chiral couplings as an example. We show that if we apply the nonlocal regularization procedure [to construct a nonlocal theory with finite mass parameter ] to t

N. Nasrallah

The extrapolation of the decay amplitudes of the pseudoscalar mesons into two photons from the soft meson limit where it is obtained from the axial-anomaly to the mass shell involves the contribution of the 0^ - continuum. These chiral symmetry breaking corrections turn out to be large. The effects of these corrections on the calculated pi ^0 decay rate, on

Dong Mi, He-Shan Song, Ying An

For a two-body quantum system, any pure state can be represented by a biorthogonal expression by means of Schmidt decomposition. Using this in the composite system which include a thermodynamic system and its surroundings, it is found that the tilde system in thermo field dynamics is just the surroundings of the real system.

A. I. Panin

Approximate solution of the ensemble representability problem for density operators of arbitrary order is obtained. This solution is closely related to the ``Q condition&#39;&#39; of A.J.Coleman. The representability conditions are formulated in orbital representation and are easy to use. They are tested numerically on the base of CI calculation of simple at

Eric Baird

Einstein&#39;s goal of producing an advanced gravitational model that was independent of special relativity&#39;s &#34;non-gravitational&#34; derivations has arguably still not been achieved. The author produced a paper in 1998 outlining a possible method of attack on the problem based on shift equivalence principles (&#34;Doppler mass shift&#34;). Some prob

V. K. B. Kota, R. Sahu

Abstrtact: Random matrix ensembles defined by a mean-field one-body plus a chaos generating random two-body interaction (called embedded ensembles of (1+2)-body interactions) predict for wavefunctions, in the chaotic domain, an essentially one parameter Gaussian forms for the energy dependence of the number of principal components NPC and the localization le

Alexander Strohmaier

This paper investigates wave-equations on spacetimes with a metric which is locally analytic in the time. We use recent results in the theory of the non-characteristic Cauchy problem to show that a solution to a wave-equation vanishing in an open set vanishes in the ``envelope&#39;&#39; of this set, which may be considerably larger and in the case of timelik

Alessandra Iozzi, Dave Witte

Let H be a closed, connected subgroup of a connected, simple Lie group G with finite center. The homogeneous space G/H has a &#34;tessellation&#34; if there is a discrete subgroup D of G, such that D acts properly discontinuously on G/H, and the double-coset space D\G/H is compact. Note that if either H or G/H is compact, then G/H has a tessellation; these a

Yuri Berest, George Wilson

Let $A_1$ be the (first) Weyl algebra, and let $G$ be its automorphism group. We study the natural action of $G$ on the space of isomorphism classes of right ideals of $A_1$ (equivalently, of finitely generated rank 1 torsion-free right $A_1$-modules). We show that this space breaks up into a countable number of orbits each of which is a finite dimensional a

Lee Mosher, Michah Sageev, Kevin Whyte

We characterize the ``best&#39;&#39; model geometries for the class of virtually free groups, and we show that there is a countable infinity of distinct ``best&#39;&#39; model geometries in an appropriate sense--these are the maximally symmetric trees. The first theorem gives several equivalent conditions on a bounded valence, cocompact tree T without valenc

M. R. Razvan

This paper is concerned with index pairs in the sense of Conley index theory for flows relative to pseudo-gradient vector fields for $C^1$-functions satisfying Palais-Smale condition. We prove a deformation theorem for such index pairs to obtain a Lusternik-Schnirelmann type result in Conley index theory.

S. Alam

Keeping in mind the several models of M(atrix) theory we attempt to understand the possible structure of the topological M(atrix) theory ``underlying&#39;&#39; these approaches. In particular we are motivated by the issue about the nature of the structure of the vacuum of the topological M(atrix) theory and how this could be related to the vacuum of the elec

Takeshi Nihei, Leszek Roszkowski, Roberto Ruiz de Austri

We compute the neutralino relic density in the minimal supersymmetric standard model by using exact expressions for the neutralino annihilation cross section into all tree-level final states, including all contributions and interference terms. We find that several final states may give comparable contributions to the relic density, which illustrates the impo

The APE Collaboration

This paper is a slightly modified and reduced version of the proposal of the {\bf apeNEXT} project, which was submitted to DESY and INFN in spring 2000. .It presents the basic motivations and ideas of a next generation lattice QCD (LQCD) computing project, whose goal is the construction and operation of several large scale Multi-TFlops LQCD engines, providin

D. E. Cox, B. Noheda, G. Shirane, Y. Uesu

Strong piezoelectricity in the perovskite-type PbZr(1-x)TixO3 (PZT) and Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) systems is generally associated with the existence of a morphotropic phase boundary (MPB) separating regions with rhombohedral and tetragonal symmetry. An x-ray study of PZN-9%PT has revealed the presence of a new orthorhombic phase at the MPB, and a near

Sher Alam

Following our recent conjecture to model the phenomenona of antiferromagnetism and superconductivity by quantum symmetry groups, we propose in the present note three toy models, namely, one based on SO_{q}(3) the other two constructed with the SO_{q}(4) and SO_{q}(5) quantum groups. Possible motivations and rationale for these choices are outlined. One of th

S. V. Dordevic, E. J. Singley, D. N. Basov, J. H. Kim

We report on generic trends in the behavior of the interlayer penetration depth $λ_c$ of several different classes of quasi two-dimensional superconductors including cuprates, Sr$_2$RuO$_4$, transition metal dichalcogenides and organic materials of the $(BEDT-TTF)_2X$-series. Analysis of these trends reveals two distinct patterns in the scaling between the v

D. W. Wang, S. Das Sarma

We study carrier interaction induced many-body effects on the excitonic optical properties of highly photoexcited one-dimensional semiconductor quantum wire systems by solving the dynamically screened Bethe-Salpeter equation using realistic Coulomb interaction between carriers. Including dynamical screening effects in the electron/hole self-energy and in the

Curtis J. Saxton, Kinwah Wu

We present a general formulation for stability analyses of radiative shocks with multiple cooling processes, longitudinal and transverse perturbations, and unequal electron and ion temperatures. Using the accretion shocks of magnetic cataclysmic variables as an illustrative application, we investigate the shock instabilities by examining the eigenfunctions o

Gregoire Tremblay, Ermanno F. Borra

We have built and tested a 3.7-m diameter liquid mirror that rotates on a ball bearing. We have carried out extensive optical tests. We find that although the ball bearing has a poor quality, the quality of the mirror, with mercury layers 1-mm thick, is surprisingly good. Taken at face values the instantaneous Strehl ratios indicate a mirror, that is not qui

Ermanno F. Borra

Liquid mirror telescopes are of interest to Astronomy because of their very low capital and operating costs. Low cost has a potentially revolutionary impact since it allows one to dedicate a large telescope to a narrowly focused project that needs a large quantity of observations. The technology is now well proven in the laboratory as well as in observatory

Subhabrata Majumdar

Study of the primary anisotropies of the Cosmic Microwave Background (CMB) can be used to determine the cosmological parameters to a very high precision. The power spectrum of the secondary CMB anisotropies due to the thermal Sunyaev-Zel&#39;dovich Effect (SZE) by clusters of galaxies, can then be studied, to constrain more cluster specific properties (like

D0 Collaboration, V. M. Abazov

We present results of searches for technirho, techniomega, and Z&#39; particles, using the decay channels technirho, techniomega, Z&#39; -> e+e-. The search is based on 124.8 pb-1 of data collected by the D0 detector at the Fermilab Tevatron during 1992-1996. In the absence of a signal, we set 95% C.L. upper limits on the cross sections for the processes p p

Zhi-zhong Xing

We interpret the newly observed muon g-2 anomaly in the framework of a leptonic Higgs doublet model with nearly degenerate neutrino masses and nearly bi-maximal neutrino mixing. Useful constraints are obtained on the rates of lepton-flavor-violating rare decays $τ\to μγ$, $μ\to e γ$ and $τ\to e γ$ as well as the $μ$-$e$ conversion ratio $R_{μe}$. We find tha

R. S. Markiewicz, C. Kusko

There is considerable evidence for some form of charge ordering on the hole-doped stripes in the cuprates, mainly associated with the low-temperature tetragonal phase, but with some evidence for either charge density waves or a flux phase, which is a form of dynamic charge-density wave. These three states form a pseudospin triplet, demonstrating a close conn

H. Chakravorty, J. van Mourik, A. C. C. Coolen

In this paper we analyse both the dynamics and the high density physics of the infinite dimensional lattice gas model for random heteropolymers recently introduced in \cite{jort}. Restricting ourselves to site-disordered heteropolymers, we derive exact closed deterministic evolution equations for a suitable set of dynamic order parameters (in the thermodynam

Ioan A. Popescu, Alfred D. Shapere

We derive the central charge and BPS equations from the low-energy effective action for N=2 SU(2) Yang-Mills theory in the Coulomb phase, using a systematic, canonical procedure. We then obtain solutions for monopole and dyon BPS states, whose core structure is described by a dual Lagrangian containing the monopole or dyon as a fundamental field. Spherically

S. E. Palmer, J. T. Chalker

We present the results of an exact diagonalization study of the spin-1/2 Heisenberg antiferromagnet on a two-dimensional version of the pyrochlore lattice, also known as the square lattice with crossings or the checkerboard lattice. Examining the low energy spectra for systems of up to 24 spins, we find that all clusters studied have non-degenerate ground st

Bok Keun Chung, Jin-Mo Chung, Seongtag Kim, Yoonbai Kim

Self-dual solitons of Chern-Simons Higgs theory are examined in curved spacetime. We derive duality transformation of the Einstein Chern-Simons Higgs theory within path integral formalism and study various aspects of dual formulation including derivation of Bogomolnyi type bound. We find all possible rotationally-symmetric soliton configurations carrying mag

Zahir A. Daya, Vatche B. Deyirmenjian, Stephen W. Morris

We report an experimental study of the primary bifurcation in electrically-driven convection in a freely suspended film. A weakly conducting, submicron thick smectic liquid crystal film was supported by concentric circular electrodes. It electroconvected when a sufficiently large voltage $V$ was applied between its inner and outer edges. The film could susta

Ming-qiu Huang, Yuan-ben Dai

Exclusive semileptonic decays B->D_1(2420)l\barνand B->D_2^*(2460)l\barνare studied at the subleading order of the heavy quark expansion. The subleading Isgur-Wise functions resulted from the kinetic energy and chromomagnetic corrections to the HQET Lagrangian are calculated by QCD sum rules in the framework of the heavy quark effective theory. The decay rat

Eric Lewin Altschuler

Besides mathematical interest, knots and knot theory have important applications in physics, chemistry, and biology. Stasiak and colleagues devised a constructive method for a knot &#34;energy&#34; using a Metropolis Monte Carlo algorithm to minimize the length of rope needed to realize a given knot for a rope of a fixed diameter. They called the resulting r

A. Hutt, F. Kruggel

The present report extends the method of fixed point clustering (Phys.Rev. E 61,5, R4691-4693, 2000) by introducing an indirect criterion for the number of clusters. The derived probability function allows an objective distinction of clustered data and data between clusters. Applications on simulated data illustrate the clustering method and the probability

J. Rasmussen, M. A. Walton

We extend our recent results on ordinary su(N) tensor product multiplicities to higher su(N) tensor products. Particular emphasis is put on four-point couplings where the tensor product of four highest weight modules is considered. The number of times the singlet occurs in the decomposition is the associated multiplicity. In this framework, ordinary tensor p

Richard Zach

After a brief flirtation with logicism in 1917-1920, David Hilbert proposed his own program in the foundations of mathematics in 1920 and developed it, in concert with collaborators such as Paul Bernays and Wilhelm Ackermann, throughout the 1920s. The two technical pillars of the project were the development of axiomatic systems for ever stronger and more co

Eduardo D Sontag

This paper deals with the theory of structure, stability, robustness, and stabilization for an appealing class of nonlinear systems which arises in the analysis of chemical networks. The results given here extend, but are also heavily based upon, certain previous work by Feinberg, Horn, and Jackson, of which a self-contained and streamlined exposition is inc

Takehiro Azuma, Satoshi Iso, Hikaru Kawai, Yuhi Ohwashi

We investigate several matrix models based on super Lie algebras, osp(1|32,R), u(1|16,16) and gl(1|32,R). They are natural generalizations of IIB matrix model and were first proposed by Smolin. In particular, we study the supersymmetry structures of these models and discuss possible reductions to IIB matrix model. We also point out that diffeomorphism invari

Guido Altarelli, Ferruccio Feruglio

We analyse proton decay in the context of simple supersymmetric SU(5) grand unified models with an extra compact spatial dimension described by the orbifold S^1/(Z_2 x Z_2&#39;). Gauge and Higgs degrees of freedom live in the bulk, while matter fields can only live at the fixed point branes. We present an extended discussion of matter interactions on the bra

Tran N. Truong

Sum rules for the off-shell isovector form factor pi -> gamma gamma* are given in terms of the pion form factor and the gamma pi ->pi pi experimental data. Similarly the corresponding sum rules for the isoscalar form factor are given in terms of the experimental photon-3 pi form factor and the gamma pi -> 3 pi amplitude. For some set of parameters, e.g. rho

G. L. Kane, M. Shifman

This is the foreword to the book we edited on the origins and early development of supersymmetry, which has been just issued by World Scientific. This book presents a view on the discovery of supersymmetry and pioneering investigations before summer 1976, mainly in the words of people who participated. It combines anecdotal descriptions and personal reminisc

Victor Kromer

The data on 13 typologically different languages have been processed using a two-parameter word length model, based on 1-displaced uniform Poisson distribution. Statistical dependencies of the 2nd parameter on the 1st one are revealed for the German texts and genre of letters.

R. S. Markiewicz

A novel form of Jahn-Teller (JT) effect in the cuprates can be reinterpreted as a conventional JT effect on a lattice with a larger unit cell. There is a triplet of instabilities, parametrized by a pseudospin, consisting of a form of the low-temperature tetragonal phase, a charge density wave phase, and a flux phase (orbital antiferromagnet). On a single 4-C

T. Egami

Recent measurements of neutron elastic and inelastic scattering suggest that the charge states are spatially inhomogeneous at two lengthscales, atomic and nanometer scales, in both the high-temperature superconducting (HTSC) cuprates and colossal magnetoresistive (CMR) manganites. We suggest that the two-phonon mechanism that controls the charge localization

Jian-Xin Li, Chung-Yu Mou, Chang-De Gong, T. K. Lee

Based on the slave-boson theory of the two-dimensional $t-t&#39;-J$ model, we calculate the superconducting condensation energy for optimally doped and overdoped high $T_{c}$ cuprates at finite temperatures using a renormalized random phase approximation. The contributions come from the mean-field part and the antiferromagnetic spin fluctuations. In the pres

Raghuveer Parthasarathy, Xiao-Min Lin, Heinrich M. Jaeger

We investigate the impact of structural disorder on electronic transport in gold nanocrystal monolayers. Arrays ranging from void-filled networks to well-ordered superlattices show clear voltage thresholds V_T due to Coulomb blockade, and temperature-independent conduction indicative of quantum tunneling. Current-voltage characteristics of arrays with and wi

G. A. Pinzon

Based on the Solar Standard Model we developed a solar model in hydrostatic equilibrium using two polytropes that describes both the &#34;radiative&#34; and &#34;convective&#34; zones of the solar interior. Then we apply small periodic and adiabatic perturbations on this bipolytropic model in order to obtain proper frequencies and proper functions. The frequ

C. Vignali, A. Comastri, F. Fiore, F. La Franca

We present a comprehensive study of the soft X-ray properties of the BeppoSAX High-Energy Large Area Survey (HELLAS) sources. A large fraction (about 2/3) of the hard X-ray selected sources is detected by ROSAT. The soft X-ray colors for many of these objects, along with the 0.5-2 keV flux upper limits for those undetected in the ROSAT band, do imply the pre

G. Risaliti, A. Marconi, R. Maiolino, M. Salvati

Quasars selected in optical surveys by means of their blue or UV excess are known to be strong emitters in the X-rays, except for Broad Absorption Line (BAL) objects. In this paper we study the X-ray emission of quasars selected through their emission line spectrum rather than their blue excess. X-ray data are obtained by cross-correlating two optical sample

D. Fargion, M. Grossi, P. G. De Sanctis Lucentini, C. Di Troia

The Ultra High Energy (UHE) neutrino scattering onto relic cosmic neutrinos in galactic and local halos offers an unique way to overcome GZK cut-off. The UHE nu secondary of UHE photo-pion decays may escape the GZK cut-off and travel on cosmic distances hitting local light relic neutrinos clustered in dark halos. The Z resonant production and the competitive

Nissim Kanekar, Jayaram N Chengalur

We report multi-epoch GMRT HI observations of the z = 0.3127 damped absorber towards the quasar PKS 1127-145, which reveal variability in both the absorption profile and the flux of the background source, over a time-scale of a few days. The observed variations cannot be explained by simple inter-stellar scintillation (ISS) models where there are only one or

Guangyong Xu, G. Aeppli, M. E. Bisher, C. Broholm

Magnetic neutron scattering provides evidence for nucleation of antiferromagnetic droplets around impurities in a doped nickel-oxide based quantum magnet. The undoped parent compound contains a spin liquid with a cooperative singlet ground state and a gap in the magnetic excitation spectrum. Calcium doping creates excitations below the gap with an incommensu

Alexander D. Hernandez, Daniel Dominguez

We study the surface barrier for magnetic field penetration in mesoscopic samples of both type I and type II superconductors. Our results are obtained from numerical simulations of the time-dependent Ginzburg-Landau equations. We calculate the dependence of the first field for flux penetration ($H_p$) with the Ginzburg-Landau parameter ($κ$) observing an inc

T. Matos, F. S. Guzman, L. A. Urena-Lopez, D. Nunez

This work is a review of the last results of research on the Scalar Field Dark Matter model of the Universe at cosmological and at galactic level. We present the complete solution to the scalar field cosmological scenario in which the dark matter is modeled by a scalar field $Φ$ with the scalar potential $V(Φ)=V_{0}(cosh {(λ\sqrt{κ_{0}}Φ)}-1)$ and the dark e

Shoichi Sasaki, Tom Blum, Shigemi Ohta

We present results of our numerical calculation of the mass spectrum for isospin one-half and spin one-half non-strange baryons, i.e. the ground and excited states of the nucleon, in quenched lattice QCD. We use a new lattice discretization scheme for fermions, domain wall fermions, which possess almost exact chiral symmetry at non-zero lattice spacing. We m

N. Arbex, F. Grassi, Y. Hama, O. Socolowski

From an analysis of various types of data obtained in relativistic nuclear collisions, the following picture has emerged in thermal and hydrodynamical descriptions: as the fluid expands and cools, particles first undergo a chemical freeze out at T_ch.~160-200 MeV then a thermal freeze out at T_th~100-140 MeV. In this paper we show how to incorporate these se

Kristen Menou, Daniel E. Vanden Berk, Zeljko Ivezic, Rita S. J. Kim

We present 13 Broad Absorption Line (BAL) quasars, including 12 new objects, which were identified in the Sloan Digital Sky Survey (SDSS) and matched within 2&#39;&#39; to sources in the FIRST radio survey catalog. The surface density of this sample of radio-detected BAL quasars is 4.5 +- 1.2 per 100 deg^2, i.e. approximately 4 times larger than previously f

Gia Dvali, Gregory Gabadadze, M. Shifman

We study some possible astrophysical implications of a very weakly coupled ultralight dilaton-type scalar field. Such a field may develop an (approximately stable) network of domain walls. The domain wall thickness is assumed to be comparable with the thickness of the luminous part of the spiral galaxies. The walls provide trapping for galactic matter. This

Nitya Nath, Tod E. Strohmayer, Jean H. Swank

We have modelled X-ray burst oscillations observed with the Rossi X-ray Timing Explorer (RXTE) from two low mass X-ray binaries (LMXB): 4U 1636-53 with a frequency of 580 Hz, and 4U 1728-34 at a frequency of 363 Hz. We have computed least squares fits to the oscillations observed during the rising phase of bursts using a model which includes emission from ei

R. S. Markiewicz, C. Kusko

An electronic phase separation model provides a natural explanation for a large variety of experimental results in the cuprates, including evidence for both stripes and larger domains, and a termination of the phase separation in the slightly overdoped regime, when the average hole density equals that on the charged stripes. Several models are presented for

V. A. Dolgushev

A two-dimensional integrable system being a deformation of the rational Calogero-Moser system is constructed via the symplectic reduction, performed with respect to the Sklyanin algebra action. We explicitly resolve the respective classical equations of motion via the projection method and quantize the system.

H. H. Wen, S. L. Li, Z. W. Zhao, Y. M. Ni

By using transport and magnetic measurement, the upper critical field $H_{c2}(T)$ and the irreversibility line $H_{irr}(T)$ has been determined. A big separation between $H_{c2}(0)$ and $H_{irr}(0)$ has been found showing the existence of a quantum vortex liquid state induced by quantum fluctuation of vortices in the new superconductor $MgB_2$. Further inves

Athanasios Dedes, Howard E. Haber

A light CP-even Higgs boson (h) with a mass of about 10 GeV could explain the recent BNL measurement of the muon anomalous magnetic moment, in the framework of a general CP-conserving two-Higgs-doublet extension of the Standard Model with no tree-level flavor-changing neutral Higgs couplings. However, the allowed Higgs mass window is quite small and the corr

J. L. Tomazelli, L. C. Costa

In this work we reexamine quantum electrodynamics of atomic eletrons in the Coulomb gauge in the dipole approximation and calculate the shift of atomic energy levels in the context of Dalibard, Dupont-Roc and Cohen-Tannoudji (DDC) formalism by considering the variation rates of physical observables. We then analyze the physical interpretation of the ordering

Harald Fritzsch, Zhi-zhong Xing

With the help of the light-quark triangle, which is essentially congruent to the rescaled unitarity triangle for a variety of textures of the quark mass matrices, we calculate the CP-violating quantity \sin 2βand the ratio of |V_{ub}| to |V_{cb}|. We find that \sin 2βis most likely to lie in the range 0.45 \leq \sin 2β\leq 0.60, a result compatible very well

J. Gutowski, G. Papadopoulos

We find a new class of cosmic string solutions with non-vanishing magnetic flux of $\mathcal{N}=1$, D=4 supergravity with a cosmological constant and coupled to any number of Maxwell and scalar multiplets. We show that these magnetic cosmic string solutions preserve 1/2 of supersymmetry. We give an explicit example of such a solution for which the complex sc

A. J. Garcia-Adeva, D. L. Huber

In this work we generalize and subsequently apply the Effective Field Renormalization Group technique to the problem of ferro- and antiferromagnetically coupled Ising spins with local anisotropy axes in geometrically frustrated geometries (kagome and pyrochlore lattices). In this framework, we calculate the various ground states of these systems and the corr

L. Moriconi

We study the intra-planar tunneling between quantum Hall samples separated by a quasi one-dimensional barrier, induced through the interaction of edge degrees of freedom with the charge density waves of a Hall crystal defined in a parallel layer. A field theory formulation is set up in terms of bosonic (2+1)-dimensional excitations coupled to (1+1)-dimension

Chong-Sun Chu, Rodolfo Russo

The multiloop amplitudes for open bosonic string in presence of a constant B-field are derived from first principles. The basic ingredients of the construction are the commutation relations for the string modes and the Reggeon vertex describing the interaction among three generic string states. The modifications due to the presence of the B-field affect non-