Enhanced antiproton production in Pb(160 AGeV)+Pb reactions: evidence   for quark gluon matter?
  The centrality dependence of the antiproton per participant ratio is studied in Pb(160 AGeV)+Pb reactions. Antiproton production in collisions of heavy nuclei at the CERN/SPS seems considerably enhanced as compared to conventional hadronic physics, given by the antiproton production rates in $pp$ and antiproton annihilation in $\bar{p}p$ reactions. This enhancement is consistent with the observation of strong in-medium effects in other hadronic observables and may be an indication of partial restoration of chiral symmetry. 
M. Bleicher, M. Belkacem, S.A. Bass, S. Soff, H. St\"ocker (LBNL,   Univ. Minnesota, Michigan State Univ., Frankfurt Univ.)