Rapidity dependence of large-p_t hadron production at RHIC

We study the dependence of parton energy loss (quenching) on rapidity in ultra-relativistic nuclear collisions at RHIC. This can provides invaluable information on the density of the medium, which should be more dilute going away from mid-rapidity, thereby reducing the effect of quenching. We predict a clear effect at moderate transverse momenta $\sim$ 3 GeV.Comment: 4 pages, latex, 3 eps figure

Excitation of Color Degrees of Freedom of Nuclear Matter and J/ψJ/\psi Suppression

In high energy nuclear collisions, the conventional Glauber model is commonly used to evaluate the contribution to $J/\psi$ suppression originating from the inelastic interaction with colorless bound nucleons. This requires an effective value for the $J/\psi$-nucleon absorption cross section which is larger than theoretically expected. On the other hand, multiple nucleon-nucleon collisions mediated by color exchange interactions, excite their color degrees of freedom. We investigate the importance of this effect and find that these excited states provide a larger cross section for $J/\psi$ absorption. We conclude that the related corrections are important to explain the effective value extrapolated from experiment.Comment: 21 pages Latex, 8 postscript figure

The Transverse Structure of the Baryon Source in Relativistic Heavy Ion Collisions

A direct method to reconstruct the transverse structure of the baryon source formed in a relativistic heavy ion collision is presented. The procedure makes use of experimentally measured proton and deuteron spectra and assumes that deuterons are formed via two-nucleon coalescence. The transverse density shape and flow profile are reconstructed for Pb+Pb collisions at the CERN-SPS. The ambiguity with respect to the source temperature is demonstrated and possible ways to resolve it are discussed.Comment: 15 pages LaTeX, 4 postscript figures, uses psfig.sty - Revised version, few minor change

Kinetic description of charmonium production in high-energy nuclear collisions

We study the evolution of charmonia as they collide with the constituents of the fireball produced in high-energy nucleus-nucleus collisions. The latter evolves in a manner controlled by the equation of state as given by lattice QCD, and is constructed in such a way that the observed hadronic spectra are correctly reproduced. A kinetic description of charmonium interactions with both quark-gluon and hadronic degrees of freedom allows to study in detail the evolution in different regimes, controlled by collision energy, kinematics and geometry. The data collected at the CERN-SPS accelerator are well described and new estimates for J/psi production at BNL-RHIC are presented.Comment: 19 pages, LaTeX, 13 .eps figure

Scanning the Quark-Gluon Plasma with Charmonium

We suggest the variation of charmonium suppression with Feynman x_F in heavy ion collisions as a novel and sensitive probe for the properties of the matter created in such reactions. In contrast to the proton-nucleus case where nuclear suppression is weakest at small x_F, final state interactions with the comoving matter create a minimum at x_F=0, which is especially deep and narrow if a quark-gluon plasma is formed. While a particularly strong effect is predicted at SPS, at the higher RHIC energy it overlaps with the expected sharp variation with x_F of nuclear effects and needs comparison with proton-nucleus data. If thermal enhancement of J/\Psi production takes over at the energies of RHIC and LHC, it will form an easily identified peak, rather than dip in x_F dependence. We predict a steep dependence on centrality and suggest that this new probe is complementary to the dependence on transverse energy, and is more sensitive to a scenario of final state interactions.Comment: 5 pages including 3 figures. Stylistic and clarifying corrections are mad

Charmonium production in high-energy nuclear collisions

We discuss some issues concerning the evolution of charmonia as they interact with the constituents of the fireball produced in high-energy nucleus-nucleus collisions. We study in detail the evolution in different regimes, controlled by collision energy, kinematics and geometry