Two- and three particle azimuthal correlations of high-pT charged hadrons in Pb-Au collisions at 158 AGeV/c

The suppression of high-pT particles observed in heavy-ion collisions at RHIC has been connected to a significant final state interaction of the hard-scattered parton with a dense color-charged medium. A recent re-evaluation of high-pt data from SPS indicates that moderate suppression may also be observed at SPS energy. The analysis of azimuthal correlations of charged hadrons at high-pT provides deeper insight into modifications of the fragmentation process and the response of the medium. Similar to observations at RHIC, significant modifications of the di-jet structure have also been observed by the CERES experiment at SPS. In order to discriminate between different scenarios of the parton-medium interaction, such as jet deflection or shock wave creation, the study has been extended to investigations of three-particle correlations. We present recent results on two- and three particle correlations from the CERES experiment and discuss possible implications on the mechanism of parton interaction with the hot and dense medium created in heavy-ion collisions at SPS. (orig.)