14,956 research outputs found

    Proof of Factorization of Fragmentation Function in Non-Equilibrium QCD

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    In this paper we prove factorization of fragmentation function in non-equilibrium QCD by using Schwinger-Keldysh closed-time path integral formalism. We use the background field method of QCD in a pure gauge in path integral approach to prove factorization of fragmentation function in non-equilibrium QCD. Our proof is valid in any arbitrary gauge fixing parameter α\alpha. This may be relevant to study hadron production from quark-gluon plasma at high energy heavy-ion colliders at RHIC and LHC.Comment: 13 pages latex, (Final Published Version, Annals of Physics

    Proton-proton physics in ALICE

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    The ALICE experiment has several unique features which makes it an important contributor to proton-proton physics at the LHC, in addition to its specific design goal of studying the physics of strongly interacting matter in heavy-ion collisions. The unique capabilities include its low transverse momentum (\pT) acceptance, excellent vertexing, particle identification over a broad \pT range and jet reconstruction. In this report, a brief review of ALICE capabilities is given for studying bulk properties of produced particles which characterize the underlying events, and the physics of heavy-flavour, quarkonia, photons, di-leptons and jets

    Renormalization Group Equation and QCD Coupling Constant in the Presence of SU(3) Chromo-Electric Field

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    We solve renormalization group equation in QCD in the presence of SU(3) constant chromo-electric field E^a with arbitrary color index a=1,2,...8 and find that the QCD coupling constant \alpha_s depends on two independent casimir/gauge invariants C_1=[E^aE^a] and C_2=[d_{abc}E^aE^bE^c]^2 instead of one gauge invariant C_1=[E^aE^a]. The \beta function is derived from the one-loop effective action. This coupling constant may be useful to study hadron formation from color flux tubes/strings at high energy colliders and to study quark-gluon plasma formation at RHIC and LHC.Comment: 13 pages latex, 4 eps figs, Eur. Phys. J.

    The Expression of Ependymin in C. elegans Roundworms - II

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    DNA and protein sequence homologies of ependymin, a neurotrophic factor of vertebrates, occur in the model organism Caenorhabditis elegans. We employed a new antibody against a bioreactive 8-aa ependymin fragment on C. elegans\u27 four larval developmental stages, to verify its expression. This project utilized immunostaining in conjunction with HRP light, fluorescence, and transmission electron microscopies, to observe ependymin expression from the worm\u27s early embryonic stage onwards to the L2 larval stage. This we witnessed most noticeably in developing embryos and along major nerve cords

    Schwinger Mechanism for Gluon Pair Production in the Presence of Arbitrary Time Dependent Chromo-Electric Field

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    We study Schwinger mechanism for gluon pair production in the presence of arbitrary time-dependent chromo-electric background field Ea(t)E^a(t) with arbitrary color index aa=1,2,...8 in SU(3) by directly evaluating the path integral. We obtain an exact expression for the probability of non-perturbative gluon pair production per unit time per unit volume and per unit transverse momentum dWd4xd2pT\frac{dW}{d^4x d^2p_T} from arbitrary Ea(t)E^a(t). We show that the tadpole (or single gluon) effective action does not contribute to the non-perturbative gluon pair production rate dWd4xd2pT\frac{dW}{d^4x d^2p_T}. We find that the exact result for non-perturbative gluon pair production is independent of all the time derivatives dnEa(t)dtn\frac{d^nE^a(t)}{dt^n} where n=1,2,....∞n=1,2,....\infty and has the same functional dependence on two casimir invariants [Ea(t)Ea(t)][E^a(t)E^a(t)] and [dabcEa(t)Eb(t)Ec(t)]2[d_{abc}E^a(t)E^b(t)E^c(t)]^2 as the constant chromo-electric field EaE^a result with the replacement: Ea→Ea(t)E^a \to E^a(t). This result may be relevant to study the production of a non-perturbative quark-gluon plasma at RHIC and LHC.Comment: 13 pages latex, Published in European Physical Journal

    Photons from Nucleus-Nucleus Collisions at Ultra-Relativistic Energies

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    We compare the photon emission rates from hot hadronic matter with in-medium mass shift and Quark Gluon Plasma (QGP). It is observed that the WA98 data can be well reproduced by hadronic initial state with initial temperature ∼200\sim 200 MeV if the universal scaling of temperature dependent hadronic masses are assumed and the evolution of temperature with time is taken from transport model or (3+1) dimensional hydrodynamics. The data can also be reproduced by QGP initial state with similar initial temperature and non-zero initial radial velocity.Comment: Talk given in the International Nuclear Physics Conference, at the University of California, Berkeley, USA, during July 30 - August 3, 200
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