402 research outputs found

    Geophysical Research

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    Contains reports on two research projects.National Aeronautics and Space Administration (Grant NGR-22-009-131)National Aeronautics and Space Administration (Grant NGR-22-009-114)National Aeronautics and Space Administration (Contract NAS 12-436

    Universal behavior of multiplicity differences in quark-hadron phase transition

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    The scaling behavior of factorial moments of the differences in multiplicities between well separated bins in heavy-ion collisions is proposed as a probe of quark-hadron phase transition. The method takes into account some of the physical features of nuclear collisions that cause some difficulty in the application of the usual method. It is shown in the Ginzburg-Landau theory that a numerical value γ\gamma of the scaling exponent can be determined independent of the parameters in the problem. The universality of γ\gamma characterizes quark-hadron phase transition, and can be tested directly by appropriately analyzed data.Comment: 15 pages, including 4 figures (in epsf file), Latex, submitted to Phys. Rev.

    A Color Mutation Model of Soft Interaction in High Energy Hadronic Collisions

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    A comprehensive model, called ECOMB, is proposed to describe multiparticle production by soft interaction. It incorporates the eikonal formalism, parton model, color mutation, branching and recombination. The physics is conceptually opposite to the dynamics that underlies the fragmentation of a string. The partons are present initially in a hadronic collision; they form a single, large, color-neutral cluster until color mutation of the quarks leads to a fission of the cluster into two color-neutral subclusters. The mutation and branching processes continue until only qqˉq\bar q pairs are left in each small cluster. The model contains self-similar dynamics and exhibits scaling behavior in the factorial moments. It can satisfactorily reproduce the intermittency data that no other model has been able to fit.Comment: 24 pages including 11 figures in revtex epsf styl

    Modified Gravity on the Brane and Dark Energy

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    We analyze the dynamics of an AdS5 braneworld with matter fields when gravity is allowed to deviate from the Einstein form on the brane. We consider exact 5-dimensional warped solutions which are associated with conformal bulk fields of weight -4 and describe on the brane the following three dynamics: those of inhomogeneous dust, of generalized dark radiation, and of homogeneous polytropic dark energy. We show that, with modified gravity on the brane, the existence of such dynamical geometries requires the presence of non-conformal matter fields confined to the brane.Comment: Revised version published in Gen. Rel. Grav. Typos corrected, updated reference and some remarks added for clarity. 11 pages, latex, no figure
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