We present transverse momentum distributions of inclusive charged particles and identified hadrons in $pp$ and Pb--Pb collisions at $rs= 2.76$ TeV, measured by ALICE at the LHC. The Pb--Pb data are presented in intervals of collision centrality and c
over transverse momenta up to 50 GeV/$c$. Nuclear medium effects are studied in terms of the nuclear modification factor raa. The results indicate a strong suppression of high-$p_T$ particles in Pb--Pb collisions, consistent with a large energy loss of hard-scattered partons in the hot, dense and long-lived medium created at the LHC. We compare the preliminary results for inclusive charged particles to previous results from RHIC and calculations from energy loss models. Furthermore, we compare the nuclear modification factors of inclusive charged particles to those of identified $pi^0$, $pi^{pm}$, K$^0_s$, and $Lambda$.
A high statistics study of high-$p_t$ two-particle azimuthal correlations in Pb-Au at $sqrt{s_{rm NN}}=17.2$ GeV, performed by the CERES experiment at the CERN-SPS, is presented. A broad away-side correlation with significant dip at $Deltaphiapproxpi
$ is observed. The shape and magnitude of the correlation is similar to measurements at RHIC. In comparison to PYTHIA calculations, we observe a significant excess of soft particles at the away-side. A study of charge correlations between trigger and associated particles disfavors vacuum fragmentation of the away-side jet and suggests significant energy transfer of the hard-scattered parton to the medium.
