In this Letter we report the first results on pi(+/-), K-+/-, p, and (p) over bar production at midrapidity (vertical bar y vertical bar < 0.5) in central Pb-Pb collisions at root 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 root s(NN) = 200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with root s(NN), which in hydrodynamic models is expected as a consequence of the increasing particle density. While the K/pi ratio is in line with predictions from the thermal model, the p/pi ratio is found to be lower by a factor of about 1.5. This deviation from thermal model expectations is still to be understood.
Pion, Kaon, and Proton Production in Central Pb-Pb Collisions at sqrt[s_{NN}]=2.76 TeV
BEOLE', Stefania;BERZANO, DARIO CARLO DOMENICO;L. Bianchi;BOTTA, Elena;BUFALINO, STEFANIA;FERRETTI, Alessandro;GAGLIARDI, Martino;GALLIO, Mauro;INNOCENTI, GIAN MICHELE;MASERA, Massimo;MILANO, LEONARDO;ORTONA, GIACOMO;POGHOSYAN, MARTIN;RAMELLO, Luciano;SCOMPARIN, ENRICO;SICILIANO, MELINDA;SITTA, Mario;VERCELLIN, Ermanno;
2012-01-01
Abstract
In this Letter we report the first results on pi(+/-), K-+/-, p, and (p) over bar production at midrapidity (vertical bar y vertical bar < 0.5) in central Pb-Pb collisions at root 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 root s(NN) = 200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with root s(NN), which in hydrodynamic models is expected as a consequence of the increasing particle density. While the K/pi ratio is in line with predictions from the thermal model, the p/pi ratio is found to be lower by a factor of about 1.5. This deviation from thermal model expectations is still to be understood.File | Dimensione | Formato | |
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