Physics of Heavy Ions Collisions: The Summary of Moriond-97

Abstract

CERN dilepton experiments have provided the most exciting data. Strong enhancement at low masses observed by CERES and HELIOS3 indicate strong modification in the vector channel in matter compared to vacuum properties. NA50 data on $J/ψ$ suppression in PbPb collisions show surprising deviation from the previous trend. The question is whether it is the expected early-time signal of QGP, or due to late-time hadronic interactions. Theoretical and experimental suggestions have been made to resolve this issue. BNL and SPS experiments have also provided rather complete data with heavy beams (Au and Pb, respectively). Very strong collective flow effects have been observed at both energies, which allow for the first time to restrict the EOS of the hadronic matter. Several observables (flow, Coulomb effects and HBT) suggest rather long evolution of systems created in heavy ion collisions and very low freeze-out densities relative to previous studies. Theory of jet stopping in QGP is becoming quantitative.