24,286 research outputs found

    ROSAT Detection and High Precision Localization of X-ray Sources in the November 19, 1978 Gamma-Ray Burst Error Box

    Get PDF
    We report on observations of the 1978, November 19 Gamma-Ray Burst source, performed with the ROSAT X-ray HRI experiment. Two sources were detected, one of which is possibly variable. The latter source is identical to the source discovered in 1981 by the EINSTEIN satellite, and recently detected by ASCA. The precise localization of these sources is given, and our data are compared with optical, radio and previous X-ray data.Comment: 10 pages with 2 figures, Accepted for publication in the Astrophysical Journal (Letters), Latex, aastex macros neede

    Critical behavior at Mott-Anderson transition: a TMT-DMFT perspective

    Full text link
    We present a detailed analysis of the critical behavior close to the Mott-Anderson transition. Our findings are based on a combination of numerical and analytical results obtained within the framework of Typical-Medium Theory (TMT-DMFT) - the simplest extension of dynamical mean field theory (DMFT) capable of incorporating Anderson localization effects. By making use of previous scaling studies of Anderson impurity models close to the metal-insulator transition, we solve this problem analytically and reveal the dependence of the critical behavior on the particle-hole symmetry. Our main result is that, for sufficiently strong disorder, the Mott-Anderson transition is characterized by a precisely defined two-fluid behavior, in which only a fraction of the electrons undergo a "site selective" Mott localization; the rest become Anderson-localized quasiparticles.Comment: 4+ pages, 4 figures, v2: minor changes, accepted for publication in Phys. Rev. Let

    Operator analysis of pTp_T-widths of TMDs

    Get PDF
    Transverse momentum dependent (TMD) parton distribution functions (PDFs), TMDs for short, are defined as the Fourier transform of matrix elements of nonlocal combinations of quark and gluon fields. The nonlocality is bridged by gauge links, which for TMDs have characteristic paths (future or past pointing), giving rise to a process dependence that breaks universality. It is possible, however, to construct sets of universal TMDs of which in a given process particular combinations are needed with calculable, process-dependent, coefficients. This occurs for both T-odd and T-even TMDs, including also the {\it unpolarized} quark and gluon TMDs. This extends the by now well-known example of T-odd TMDs that appear with opposite sign in single-spin azimuthal asymmetries in semi-inclusive deep inelastic scattering or in the Drell-Yan process. In this paper we analyze the cases where TMDs enter multiplied by products of two transverse momenta, which includes besides the pTp_T-broadening observable, also instances with rank two structures. To experimentally demonstrate the process dependence of the latter cases requires measurements of second harmonic azimuthal asymmetries, while the pTp_T-broadening will require measurements of processes beyond semi-inclusive deep inelastic scattering or the Drell-Yan process. Furthermore, we propose specific quantities that will allow for theoretical studies of the process dependence of TMDs using lattice QCD calculations.Comment: 10 pages, no figures; expanded discussions, matches version accepted by JHE

    Single spin asymmetries from a single Wilson loop

    Get PDF
    We study the leading-power gluon transverse momentum dependent distributions (TMDs) of relevance to the study of asymmetries in the scattering off transversely polarized hadrons. Next-to-leading-order perturbative calculations of these TMDs show that at large transverse momentum they have common dynamical origins, but that in the limit of small longitudinal momentum fraction xx only one origin remains. We find that in this limit only the dipole-type gluon TMDs survive and become identical to each other. At small xx they are all given by the expectation value of a single Wilson loop inside the transversely polarized hadron, the so-called spin-dependent odderon. This universal origin of transverse spin asymmetries at small xx is of importance to current and future experimental studies, paving the way to a better understanding of the role of gluons in the three-dimensional structure of spin-polarized protons.Comment: 5 pages, 1 figure. Various changes to the text, additional references, conclusions unchanged, version accepted for publication in Physical Review Letter

    Flexible Automatic Scheduling For Autonomous Telescopes: The MAJORDOME

    Full text link
    We have developped a new method for the scheduling of astronomical automatic telescopes, in the framework of the autonomous TAROT instrument. The MAJORDOME software can handle a variety of observations, constrained, periodic, etc., and produces a timeline for the night, which may be modified at any time to take into account the specific conditions of the night. The MAJORDOME can also handle target of opportunity observations without delay.Comment: 16 pages, 6 figures, to appear in Experimental Astronom

    The development of a resource-efficient photovoltaic system

    No full text
    This paper presents the measures taken in the demonstration of the photovoltaic case study developed within the European project ‘Towards zero waste in industrial networks’ (Zerowin), integrating the D4R (Design for recycling, repair, refurbishment and reuse) criteria at both system and industrial network level. The demonstration is divided into three phases. The first phase concerns the development of a D4R photovoltaic concept, the second phase focused on the development of a specific component of photovoltaic systems and the third phase was the demonstration of the D4R design in two complete photovoltaic systems (grid-connected and stand-alone). This paper includes a description of the installed photovoltaic systems, including a brief summary at component level of the lithium ion battery system and the D4R power conditioning system developed for the pilot installations. Additionally, industrial symbioses within the network associated with the photovoltaic systems and the production model for the network are described

    Sum rules for correlation functions of ionic mixtures in arbitrary dimension d≄2d\geq 2

    Full text link
    The correlations in classical multi-component ionic mixtures with spatial dimension d≄2d\geq 2 are studied by using a restricted grand-canonical ensemble and the associated hierarchy equations for the correlation functions. Sum rules for the first few moments of the two-particle correlation function are derived and their dependence on dd is established. By varying dd continuously near d=2d=2 it is shown how the sum rules for the two-dimensional mixture are related to those for mixtures at higher dd.Comment: 19 page

    Further search for a neutral boson with a mass around 9 MeV/c2

    Get PDF
    Two dedicated experiments on internal pair conversion (IPC) of isoscalar M1 transitions were carried out in order to test a 9 MeV/c2 X-boson scenario. In the 7Li(p,e+e-)8Be reaction at 1.1 MeV proton energy to the predominantly T=0 level at 18.15 MeV, a significant deviation from IPC was observed at large pair correlation angles. In the 11B(d,n e+e-)12C reaction at 1.6 MeV, leading to the 12.71 MeV 1+ level with pure T=0 character, an anomaly was observed at 9 MeV/c2. The compatibility of the results with the scenario is discussed.Comment: 12 pages, 5 figures, 2 table

    Detecting Dark Matter Annihilation with CMB Polarization : Signatures and Experimental Prospects

    Full text link
    Dark matter (DM) annihilation during hydrogen recombination (z ~ 1000) will alter the recombination history of the Universe, and affect the observed CMB temperature and polarization fluctuations. Unlike other astrophysical probes of DM, this is free of the significant uncertainties in modelling galactic physics, and provides a method to detect and constrain the cosmological abundances of these particles. We parametrize the effect of DM annihilation as an injection of ionizing energy at a rate e_{dm}, and argue that this simple "on the spot'' modification is a good approximation to the complicated interaction of the annihilation products with the photon-electron plasma. Generic models of DM do not change the redshift of recombination, but change the residual ionization after recombination. This broadens the surface of last scattering, suppressing the temperature fluctuations and enhancing the polarization fluctuations. We use the temperature and polarization angular power spectra to measure these deviations from the standard recombination history, and therefore, indirectly probe DM annihilation. (abridged)Comment: 13 pages, 8 figures, submitted to PR
    • 

    corecore