7,100 research outputs found

    Early thermalization of quark-gluon matter by elastic 3-to-3 scattering

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    The early thermalization is crucial to the quark-gluon plasma as a perfect liquid and results from many-body scattering. We calculate squared amplitudes for elastic parton-parton-parton scattering in perturbative QCD. Transport equations with the squared amplitudes are established and solved to obtain the thermalization time of initially produced quark-gluon matter and the initial temperature of quark-gluon plasma. We find that the thermalization times of quark matter and gluon matter are different.Comment: 5 pages, 1 figure, proceedings for Extreme QCD 201

    Early Thermalization at RHIC

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    Triple-gluon elastic scatterings are briefly reviewed since the scatterings explain the early thermalization puzzle in Au-Au collisions at RHIC energies. A numerical solution of the transport equation with the triple-gluon elastic scatterings demonstrates gluon momentum isotropy achieved at a time of the order of 0.65 fm/c. Triple-gluon scatterings lead to a short thermalization time of gluon matter.Comment: LaTex, 8 pages and 4 figures, talk presented in the Weihai workshop on relativistic heavy ion collision

    Early thermalization of quark-gluon matter initially created in high-energy nucleus-nucleus collisions

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    Elastic parton-parton-parton scattering is briefly reviewed and is included in transport equations of quark-gluon matter. We solve the transport equations and get thermal states from initially produced quark-gluon matter. Both gluon matter and quark matter take early thermalization, but gloun matter has a shorter thermalization time than quark matter.Comment: 7 pages, 4 figures, proceedings for the 29th Winter Workshop on Nuclear Dynamic

    Origin of Temperature of Quark-Gluon Plasma in Heavy Ion Collisions

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    Initially produced quark-gluon matter at RHIC and LHC does not have a temperature. A quark-gluon plasma has a high temperature. From this quark-gluon matter to the quark-gluon plasma is the early thermalization or the rapid creation of temperature. Elastic three-parton scattering plays a key role in the process. The temperature originates from the two-parton scattering, the three-parton scattering, the four-parton scattering and so forth in quark-gluon matter.Comment: 6 pages, proceedings for the XXX-th International Workshop on High Energy Physic

    Integral bases of cluster algebras and representations of tame quivers

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    In \cite{CK2005} and \cite{SZ}, the authors constructed the bases of cluster algebras of finite types and of type A~1,1\widetilde{A}_{1,1}, respectively. In this paper, we will deduce Z\mathbb{Z}-bases for cluster algebras of affine types.Comment: 28 pages, an improvement of arXiv:0811.367

    Temperature dependence of cross sections for meson-meson nonresonant reactions in hadronic matter

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    We study unpolarized cross sections for the endothermic nonresonant reactions: pion pion to rho rho for I=2, KK to K*K* for I=1, KK* to K*K* for I=1, pion K to rho K* for I=3/2, pion K* to rho K* for I=3/2, rho K to rho K* for I=3/2, and pion K* to rho K for I=3/2, which take place in hadronic matter. We provide a potential that is given by perturbative QCD with loop corrections at short distances, becomes a distance-independent and temperature-dependent value at long distances, and has a spin-spin interaction with relativistic modifications. The Schrodinger equation with the potential yields temperature-dependent meson masses and mesonic quark-antiquark relative-motion wave functions. In the first Born approximation with the quark-interchange mechanism, the temperature dependence of the potential, meson masses and wave functions brings about temperature dependence of unpolarized cross sections for the seven nonresonant reactions. Noticeably, rapid changes of pion and K radii cause an increase in peak cross sections while the temperature approaches the critical temperature. Parametrizations of the numerical cross sections are given for their future applications in heavy ion collisions.Comment: 24 pages, 8 figure

    A Z\mathbb{Z}-basis for the cluster algebra associated to an affine quiver

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    The canonical bases of cluster algebras of finite types and rank 2 are given explicitly in \cite{CK2005} and \cite{SZ} respectively. In this paper, we will deduce Z\mathbb{Z}-bases for cluster algebras for affine types A~n,n,D~\widetilde{A}_{n,n},\widetilde{D} and E~\widetilde{E}. Moreover, we give an inductive formula for computing the multiplication between two generalized cluster variables associated to objects in a tube.Comment: 21 page

    Relation between quark-antiquark potential and quark-antiquark free energy in hadronic matter

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    In the high-temperature quark-gluon plasma and its subsequent hadronic matter created in a high-energy nucleus-nucleus collision, the quark-antiquark potential depends on the temperature. The temperature-dependent potential is expected to be derived from the free energy obtained in lattice gauge theory calculations. This requires one to study the relation between the quark-antiquark potential and the quark-antiquark free energy. When the system's temperature is above the critical temperature, the potential of a heavy quark and a heavy antiquark almost equals the free energy, but the potential of a light quark and a light antiquark, of a heavy quark and a light antiquark and of a light quark and a heavy antiquark is substantially larger than the free energy. When the system's temperature is below the critical temperature, the quark-antiquark free energy can be taken as the quark-antiquark potential. This allows one to apply the quark-antiquark free energy to study hadron properties and hadron-hadron reactions in hadronic matter.Comment: 11 page

    Charmonium dissociation in collision with phi meson in hadronic matter

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    The phi-charmonium dissociation reactions in hadronic matter are studied. Unpolarised cross sections for 12 reactions are calculated in the Born approximation, in the quark-interchange mechanism and with a temperature-dependent quark potential. The potential leads to remarkable temperature dependence of the cross sections. With the cross sections and the phi distribution function we calculate the dissociation rates of the charmonia in the interactions with the phi meson in hadronic matter. The dependence of the rates on temperature and charmonium momentum is meaningful to the influence of phi mesons on charmonium suppression.Comment: 21 pages, 12 figure

    Realizing Enveloping Algebras via Varieties of Modules

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    By using the Ringel-Hall algebra approach, we investigate the structure of the Lie algebra L(Λ)L(\Lambda) generated by indecomposable constructible sets in the varieties of modules for any finite dimensional C\mathbb{C}-algebra Λ.\Lambda. We obtain a geometric realization of the universal enveloping algebra R(Λ)R(\Lambda) of L(Λ).L(\Lambda). This generalizes the main result of Riedtmann in \cite{R}. We also obtain Green's theorem in \cite{G} in a geometric form for any finite dimensional C\mathbb{C}-algebra Λ\Lambda and use it to give the comultiplication formula in $R(\Lambda).
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