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K^0_S and {\Lambda} production in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV

Abstract : The ALICE measurement of K^0_S and {\Lambda} production at mid-rapidity in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV is presented. The transverse momentum (pT) spectra are shown for several collision centrality intervals and in the pT range from 0.4 GeV/c (0.6 GeV/c for {\Lambda}) to 12 GeV/c. The pT dependence of the {\Lambda}/K^0_S ratios exhibits maxima in the vicinity of 3 GeV/c, and the positions of the maxima shift towards higher pT with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate pT is not observed in pp interactions at sqrt(s) = 0.9 TeV and at sqrt(s) = 7 TeV. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured pT spectra above 2 GeV/c progressively decouple from hydrodynamical-model calculations. For higher values of pT, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the pT dependence of the {\Lambda}/K^0_S ratio.
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Contributor : Sylvie Flores <>
Submitted on : Tuesday, July 23, 2013 - 8:00:07 AM
Last modification on : Wednesday, September 16, 2020 - 4:08:18 PM

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B. Abelev, Laurent Aphecetche, A. Baldisseri, V. Barret, N. Bastid, et al.. K^0_S and {\Lambda} production in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV. Physical Review Letters, American Physical Society, 2013, 111, pp.222301. ⟨10.1103/PhysRevLett.111.222301⟩. ⟨in2p3-00847194⟩



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