Elliptic flow from a parton cascade

The dependence of elliptic flow at RHIC energies on the effective parton scattering cross section is calculated using the ZPC parton cascade model. We show that the v_2 measure of elliptic flow saturates early in the evolution before the hadronization transition to a rather large value ~0.05-0.15 as \sigma_g varies from 2-10 mb and thus is a sensitive probe of the dynamics in the plasma phase.Comment: 13 pages, 4 figure

Energy loss of partons traversing a QGP fluid

We analyse the azimuthal correlation function for high p_T charged hadrons in Au+Au collisions at the RHIC energy. By using a dynamical model in which hydrodynamics is combined with explicit propagation of high p_T partons, we study the effect of the intrinsic transverse momentum of initial partons on the azimuthal back-to-back correlations.Comment: 4 pages, 2 figures, talk given at PaNic02, Osaka, Japan, September 30 - October 4, 200

Heavy Quark Radiative Energy Loss in QCD Matter

Heavy quark medium induced radiative energy loss is derived to all orders in opacity, $(L/\lambda_g)^n$. The analytic expression generalizes the GLV opacity expansion for massless quanta to heavy quarks with mass $M$ in a QCD plasma with a gluon dispersion characterized by an asymptotic plasmon mass, $m_g=gT/\sqrt{2}$. Remarkably, we find that the general result is obtained by simply shifting all frequencies in the GLV series by $(m_g^2+x^2 M^2)/(2 x E)$. Numerical evaluation of the first order in opacity energy loss shows that both charm and bottom energy losses are much closer to the incoherent radiation limit than light partons in nuclear collisions at both RHIC and LHC energies. However, the radiation lengths of heavy quarks remain large compared to nuclear dimensions and hence high $p_T$ heavy quark production is volume rather than surface dominated.Comment: 32 pages, 14 figure

Jet Tomography of Au+Au Reactions Including Multi-gluon Fluctuations

Jet tomography is the analysis of the attenuation pattern of high transverse momentum hadrons to determine certain line integral transforms of the density profile of the QCD matter produced in ultra-relativistic nuclear collisions. In this letter, we calculate the distortion of jet tomography due to multi-gluon fluctuations within the GLV radiative energy loss formalism. We find that fluctuations of the average gluon number, ~ 3 for RHIC initial conditions, reduce the attenuation of pions by approximately a factor Z ~ 0.4-0.5. Therefore the plasma density inferred from jet tomography without fluctuations must be enhanced by a factor 1/Z ~ 2.Comment: 6 pages, 4 .eps figures, uses REVTEX and bbox.st

Jet quenching in thin plasmas

We investigate the energy loss of quarks and gluons produced in hard processes resulting from final state rescatterings in a finite quark-gluon plasma. The angular distribution of the soft gluon bremsstrahlung induced by n_s=1 rescatterings in the plasma is computed in the Gyulassy-Wang model. Special focus is on how the interference between the initial hard radiation amplitude, the multiple induced Gunion-Bertsch radiation amplitudes, and gluon rescattering amplitudes modifies the classical parton cascade results.Comment: 4 pages in Latex and 3 EPS figures, Proceedings of the Quark Matter'99 Conference, 10-15 May, 1999, Torin

Where is the charm quark energy loss at RHIC?

Heavy quark energy loss in a hot QCD plasma is computed taking into account the competing effects due to suppression of zeroth order gluon radiation below the plasma frequency and the enhancement of gluon radiation due to first order medium induced Bremsstrahlung. The results suggest a surprising degree of cancellation between the two medium effects for charm quarks and provides a possible explanation for the null effect observed by PHENIX in the prompt electron spectrum in Au+Au at $\surd s=$ 130 AGeV.Comment: 9 pages with 3 ps figure

Finding the remnants of lost jets at RHIC

A fast jet propagating through partonic matter loses energy by medium-induced gluon radiation. We propose a method to detect the energy loss of jets and the final-state interaction of the radiated gluons and the jets with the partonic medium. By embedding jets and radiated energy into a parton cascade, we find that the fate of lost jets can be studied by analyzing the momentum distribution of soft hadrons relative to the jet axis.Comment: 5 pages, Revtex, 2 figs, Revised Version, To appear in PL

Searching for the Next Yukawa Phase of QCD

QCD predicts that the interactions between quarks and gluons change from a confining to a screened Yukawa form above a critical temperature $T_c\sim 150$ MeV. In this talk, I review some of the key observables in heavy ion reactions which are being used to search for this new partonic Yukawa phase at SPS and RHIC. These include collective observables such as $dE_\perp/dyd^2p_\perp$, meson interferometry, jet quenching, and $J/\psi$ suppression.Comment: 24 pages (PTPTex style files included) with 26 eps,ps figures using epsf,psfig. To appear in Proc. of 14th Nishinomiya-Yukawa Memorial Symposium Nov. 1999, Japan; updated with a critique of the CERN press release Feb. 8, 200

The Next Yukawa Phase of QCD at RHIC

QCD predicts the existence of a new partonic Yukawa phase above a critical temperature $T_c\sim 150$ MeV. I review some of the key observables which will be used in heavy ion reactions to search for this new phase at RHIC. Systematics of collective observables ($N_{ch},E_\perp)$, flow patterns, meson interferometry, jet quenching, and $J/\psi$ suppression are discussed. This talk is updated with the first data from RHIC.Comment: 18 pages, including 18 figures. Invited talk given at the 7th International Conference on Nucleus-Nucleus Collisions (NN2000), Strasbourg, 3-7 July 2000, to appear in the Proceedings in Nucl. Phys. A (W. Noerenberg, D. Guerreau, and V. Metag, editors