K0s and Lambda production in Pb–Pb collisions at sqrt(sNN)=2.76 TeV

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2.76 TeV
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The ALICE measurement of K0s 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/K0s 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 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 pT, mechanisms involving recombination of constituent quarks were proposed. They are able to describe approximately the shape of the
pT dependence of Lambda/K0s ratio.

Info: arXiv version significantly longer than PRL and contains two more figures:
ALI-PUB-55067  (CERN, arXiv, PRL)
ALI-PUB-55071  (CERN, arXiv)
ALI-PUB-55075  (CERN, arXiv)
ALI-PUB-55079  (CERN, arXiv, PRL)
ALI-PUB-55083  (CERN, arXiv, PRL)