The status of the energy dependence of the chemical freeze-out temperature and chemical potential obtained in heavy ion collisions is presented. Recent proposals for chemical freeze-out conditions are compared.

We present some of the universal properties in ion-atom interaction derived from a newly formulated quantum-defect theory for the -1/r4 type of long-range interactions. For bound states, we present the universal bound spectrum, namely, the equivalent of the Rydberg formula, for ion-atom systems. For scattering, we introduce the concept of a universal resonance spectrum to give a systematic unde...

Dilepton production associated with minijets is calculated in ultrarela-tivistic heavy ion collisions using the first order approximation of the dilepton fragmentation functions of quarks and gluons. The full QCD evolution of the fragmentation functions is also studied. We find that the dilepton pairs from the fragmentation of minijets are comparable to direct Drell-Yan at √ s = 200 AGeV for sm...

Ue discuss in this paper some theoritical informations that one can get from experimental results of heavy ions beams-target interaction in the case of gas and plasma with electronic density 17 18 — 3 ranging between 10 and 10 e.cm We focus on tuo particular points : Corrections to the dominant behavior of stopping pouer and dynamical influence on beam charge state.