We utilize the Parton Cascade Model to study the evolution of charm quarks propagating through a thermal brick of QCD matter. We determine the energy loss and the transport coefficient 'q' for charm quarks. The calculations are done at a constant temperature of 350 MeV and the results are compared to analytical calculations of heavy quark energy loss in order to validate the applicability of using a Parton Cascade Model for the study of heavy quarks dynamics in hot and dense QCD matter.

Xe+Xe collision at relativistic energies may provide us with a partonic system whose size is approximately in between those produced by p+p and Pb+Pb collisions. The experimental results on anisotropic flow in Xe+Xe and Pb+Pb collisions should provide us with an opportunity to study system size dependence of v2. In the present work, we have used AMPT transport model to calculate charged particles' v2 for Xe+Xe collisions at √ sNN =5.44 TeV. We have also tried to demonstrate the no. of constituent quark, Nq, and mT scaling of the elliptic flow. We find that nq scaling of v2 is not observed for the identified hadrons. The v2 results from Xe+Xe collisions have also been compared to Pb+Pb collisions at √ sNN = 5.02 TeV. We find that flow of charged particles in (50-60)% central collisions for Xenon nuclei is almost 30% less than particle flow developed in lead ion collisions, implying the important role the system size play in development of particle collective motion in relativistic heavy ion collisions.

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Abstract.We study the production of heavy quarks, charm at BNL-RHIC ( √ s = 200 GeV/nucleon) and CERN-LHC ( √ s = 5.5 TeV/nucleon) and bottom at CERN-LHC from heavy ions colliding at relativistic energies. We consider initial fusion of gluons (and quark-anti-quark annihilation), pre-thermal parton interactions and interactions in thermalized quark gluon plasma. We also consider free-streaming partons as another extreme and compare the results with those from a thermalized plasma of partons. The pre-thermal contribution is calculated by considering interaction among partons having large transverse momenta (jet-partons) after the initial interaction, and from passage of these partons through a thermalized quark gluon plasma. Charm production from pre-thermal processes is found to be comparable to that from prompt (initial) interactions at LHC. It is suggested that this may have important implications for the study of nuclear modification factor, R AA as well as for back-to-back correlation of heavy quarks and production of dileptons having a large mass.PACS numbers:

We study the correlations of heavy quarks produced in relativistic heavy ion collisions and find them to be quite sensitive to the effects of the medium and the production mechanisms. In order to put this on a quantitative footing, as a first step, we analyze the azimuthal, transverse momentum, and rapidity correlations of heavy quark-anti quark (QQ) pairs in pp collisions at O(α 3 s ). This sets the stage for the identification and study of medium modification of similar correlations in relativistic collision of heavy nuclei at the Large Hadron Collider. Next we study the additional production of charm quarks in heavy ion collisions due to multiple scatterings, viz., jet-jet collisions, jet-thermal collisions, and thermal interactions. We find that these give rise to azimuthal correlations which are quite different from those arising from prompt initial production at leading order and at next to leading order.