Soft open charm production in Heavy-Ion Collisions.

The effects of strong longitudinal color electric fields on the open charm production in nucleus-nucleus (A+A) collisions at 200A GeV are investigated within the framework of the HIJING/BB[over ] v2.0 model. A threefold increase of the effective string tension due to in-medium effects in A+A collisions results in a sizable ( approximately 60%-70%) enhancement of the total charm production cross sections (sigma (cc)(NN)). The nuclear modification factor shows a suppression at moderate transverse momentum (p(T)) consistent with BNL Relativistic Heavy Ion Collider data. At Large Hadron Collider energies the model predicts an increase of sigma (cc)(NN) by approximately an order of magnitude.

Non-Abelian energy loss at finite opacity.

A systematic expansion in opacity, L/lambda, is used to clarify the nonlinear behavior of induced gluon radiation in quark-gluon plasmas. The inclusive differential gluon distribution is calculated up to second order in opacity and compared to the zeroth order (factorization) limit. The opacity expansion makes it possible to take finite kinematic constraints into account that suppress jet quenching in nuclear collisions below RHIC (square root of s = 200 AGeV) energies.

Energy and centrality dependence of rapidity densities at RHIC energies.

The energy and centrality dependence of the charged multiplicity per participant nucleon is shown to be able to differentiate between final state saturation and fixed scale perturbative QCD models of initial entropy production in high-energy heavy-ion collisions. The energy dependence is shown to test the nuclear enhancement of the minijet component of the initial conditions, while the centrality dependence provides a key test of whether gluon saturation is reached at RHIC energies. The HIJING model predicts that the rapidity density per participant increases with centrality, while the saturation model prediction is essentially independent of centrality.

High p(T) azimuthal asymmetry in noncentral A + A at RHIC.

The high p(T)>3 GeV azimuthal asymmetry, v(2)(p(T)), in noncentral nuclear collisions at RHIC is shown to be a sensitive measure of the initial parton density distribution of the produced quark-gluon plasma. A generalization of the Gyulassy-Lévai-Vitev non-Abelian energy loss formalism including Bjorken (1+1)D expansion as well as important kinematic constraints is used.