Collection of Ceres Results

CERES is a dilepton experiment at the CERN SPS, known for its observation of enhanced production of low mass ee pairs in collisions between heavy nuclei [ 1]. The fact that the excess pairs had invariant masses above approximately twice the pion mass and that the enhancement was absent in proton induced collisions [ 2] pointed towards pion annihilation ππ → ρ → ee as the additional source of lepton pairs. To fully account for the measured spectrum, however, the shape of the ρ peak needs to be modified. Theoretical models expect a shift of the peak to lower masses [ 3] or a broadening and a slight shift up [ 4] when ρ is immersed in high density hadronic matter. Testing the predictions of (and possibly distinguishing between) the two scenarios was among the objectives of the CERES upgrade. In this note I list several results of the ongoing analysis of the data from the last run of the upgraded CERES. For the sake of limited space two of the topics presented in the talk, the elliptic flow of Λ and the back-to-back correlations, are omitted. These results are described in detail in [ 5] and [ 6], respectively.