Pion, Kaon, and Proton Production in Central Pb-Pb Collisions at s NN = 2.76 TeV

In this Letter we report the first results on π ± , K ± , p, and p production at midrapidity (|y| s NN = 2.76  TeV, measured by the ALICE experiment at the LHC. The p T distributions and yields are compared to previous results at √ s NN = 200  GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with √ s NN, which in hydrodynamic models is expected as a consequence of the increasing particle density. While the K/π ratio is in line with predictions from the thermal model, the p/π ratio is found to be lower by a factor of about 1.5. This deviation from thermal model expectations is still to be understood.