No Arabic abstract
We present numerical simulations of the SU(2) Boltzmann-Vlasov equation including both hard elastic particle collisions and soft interactions mediated by classical Yang-Mills fields. We provide an estimate of the coupling of jets to a hot isotropic plasma, which is independent of infrared cutoffs. In addition, we investigate jet propagation in anisotropic plasmas, as created in heavy-ion collisions. The broadening of jets is found to be stronger along the beam line than in azimuth due to the creation of field configurations with B_t>E_t and E_z>B_z via plasma instabilities.
We investigate the quark spectrum in the quark-gluon plasma phase near color superconducting (CS) and chiral phase transitions. Owing to the precursory soft modes of the phase transitions, there appear novel excitaion spectra: In the CS transition, the quark matter shows non-Fermi liquid behavior and leads to the pseudogap in the density of states of quarks. In the chiral transition, three collective excitations appear in the quark spectrum.
We have implemented the LPM effect into a microscopic transport model with partonic degrees of freedom by following the algorithm of Zapp & Wiedemann. The Landau-Pomeranchuk-Migdal (LPM) effect is a quantum interference process that modifies the emission of radiation in the presence of a dense medium. In QCD this results in a quadratic length dependence for radiative energy loss. This is an important effect for the modification of jets by their passage through the QGP. We verify the leading parton energy loss in the model against the leading order Baier-Dokshitzer-Mueller-Peigne-Schiff-Zakharov (BDMPS-Z) result. We apply our model to the recent observations of the modification of di-jets at the LHC.
We study the effect of shear and bulk viscosities on the heavy quark transport coefficient within the matrix model of semi QGP. Dissipative effects are incorporated through the first-order viscous correction in the quark/antiquark and gluon distribution function. It is observed that while the shear viscosity effects reduces the drag of heavy quark the bulk viscosity effects increase the drag and the diffusion coefficients of heavy quark. For finite values of {eta}/s and {xi}/s, Polyakov loop further decreases the drag and the diffusion coefficients as compared to perturbative QCD.
We give a reminder on the major inputs of microscopic hadronic transport models and on the physics aims when describing various aspects of relativistic heavy ion collisions at SPS energies. We then first stress that the situation of particle ratios being reproduced by a statistical description does not necessarily mean a clear hint for the existence of a fully isotropic momentum distribution at hadrochemical freeze-out. Second, a short discussion on the status of strangeness production is given. Third we demonstrate the importance of a new collective mechanism for producing (strange) antibaryons within a hadronic description, which guarantees sufficiently fast chemical equilibration.
Quenching of gluonic jets and heavy quark production in Au+Au collisions at RHIC can be understood within the pQCD based 3+1 dimensional parton transport model BAMPS including pQCD bremsstrahlung $2 leftrightarrow 3$ processes. Furthermore, the development of conical structures induced by gluonic jets is investigated in a static box for the regimes of small and large dissipation.