33,538 research outputs found

    Hard exclusive photoproduction of Φ\Phi and J/ΨJ/\Psi mesons

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    We present predictions for differential cross sections for the reaction γp→Φp\gamma p \to \Phi p and give an outlook to which extent our calculations may be generalized to the photoproduction of J/ΨJ/\Psi mesons. Our results are obtained within perturbative QCD treating the proton as a quark-diquark system.Comment: 4 pages, 1 figure, uses Elsevier style espcrc1.st

    Evidence for an oscillatory singularity in generic U(1) symmetric cosmologies on T3Ă—RT^3 \times R

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    A longstanding conjecture by Belinskii, Lifshitz, and Khalatnikov that the singularity in generic gravitational collapse is locally oscillatory is tested numerically in vacuum, U(1) symmetric cosmological spacetimes on T3Ă—RT^3 \times R. If the velocity term dominated (VTD) solution to Einstein's equations is substituted into the Hamiltonian for the full Einstein evolution equations, one term is found to grow exponentially. This generates a prediction that oscillatory behavior involving this term and another (which the VTD solution causes to decay exponentially) should be observed in the approach to the singularity. Numerical simulations strongly support this prediction.Comment: 15 pages, Revtex, includes 12 figures, psfig. High resolution versions of figures 7, 8, 9, and 11 may be obtained from anonymous ftp to ftp://vela.acs.oakland.edu/pub/berger/u1genfig

    Hunting Local Mixmaster Dynamics in Spatially Inhomogeneous Cosmologies

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    Heuristic arguments and numerical simulations support the Belinskii et al (BKL) claim that the approach to the singularity in generic gravitational collapse is characterized by local Mixmaster dynamics (LMD). Here, one way to identify LMD in collapsing spatially inhomogeneous cosmologies is explored. By writing the metric of one spacetime in the standard variables of another, signatures for LMD may be found. Such signatures for the dynamics of spatially homogeneous Mixmaster models in the variables of U(1)-symmetric cosmologies are reviewed. Similar constructions for U(1)-symmetric spacetimes in terms of the dynamics of generic T2T^2-symmetric spacetime are presented.Comment: 17 pages, 5 figures. Contribution to CQG Special Issue "A Spacetime Safari: Essays in Honour of Vincent Moncrief

    Inefficiency and productivity growth in banking: a comparison of stochastic econometric and thick frontier methods

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    A comparison of alternative methods for estimating inefficiency and productivity growth in banking, showing that inefficiencies are sufficiently large to dominate scale economies and that measured technological progress has been small, or even negative, as a result of institutional events that occurred during 1977-88.Banks and banking - Costs ; Production (Economic theory)

    Numerical simulations of generic singuarities

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    Numerical simulations of the approach to the singularity in vacuum spacetimes are presented here. The spacetimes examined have no symmetries and can be regarded as representing the general behavior of singularities. It is found that the singularity is spacelike and that as it is approached, the spacetime dynamics becomes local and oscillatory.Comment: typos correcte

    Covariant baryon charge radii and magnetic moments in a chiral constituent quark model

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    The charge radii and magnetic moments of all the light and strange baryons are investigated within the framework of a constituent quark model based on Goldstone-boson-exchange dynamics. Following the point-form approach to relativistic quantum mechanics, the calculations are performed in a manifestly covariant manner. Relativistic (boost) effects have a sizeable influence on the results. The direct predictions of the constituent quark model are found to fall remarkably close to the available experimental data.Comment: 6 pages, 4 table

    Consistency conditions for regulatory analysis of financial institutions: a comparison of frontier efficiency methods

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    We propose a set of consistency conditions that frontier efficiency measures should meet to be most useful for regulatory analysis or other purposes. The efficiency estimates should be consistent in their efficiency levels, rankings, and identification of best and worst firms, consistent over time and with competitive conditions in the market, and consistent with standard nonfrontier measures of performance. We provide evidence on these conditions by evaluating and comparing efficiency estimates on U.S. bank efficiency from variants of all four of the major approaches -- DEA, SFA, TFA, and DFA -- and find mixed results.Financial institutions ; Bank supervision
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