In this Letter we report the first results on pi, K, p, production at midrapidity (jyj < 0:5) in central Pb-Pb collisions at sNN= 2.76 TeV, measured by the ALICE experiment at the LHC. The pT distributions and yields are compared to previous results at sNN= 200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with fsNN= 2.76, 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 √sNN=2.76TeV / Abelev, B.; Adam, J.; Adamová, D.; Adare, A. M.; Aggarwal, M. M.; Aglieri Rinella, G.; Agocs, A. G.; Aguilar Salazar, S.; Bufalino, S.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 109:25(2012), p. 252301. [10.1103/PhysRevLett.109.252301]

### Pion, kaon, and proton production in central Pb-Pb collisions at √sNN=2.76TeV

#### Abstract

In this Letter we report the first results on pi, K, p, production at midrapidity (jyj < 0:5) in central Pb-Pb collisions at sNN= 2.76 TeV, measured by the ALICE experiment at the LHC. The pT distributions and yields are compared to previous results at sNN= 200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with fsNN= 2.76, 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.
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Descrizione: Pion, Kaon, and Proton Production in Central Pb-Pb Collisions at sNN=2.76 TeV
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Utilizza questo identificativo per citare o creare un link a questo documento: `https://hdl.handle.net/11583/2711806`