Abstract
The ALICE measurement of and production at midrapidity in Pb-Pb collisions at is presented. The transverse momentum () spectra are shown for several collision centrality intervals and in the range from ( for ) to . The dependence of the ratios exhibits maxima in the vicinity of , and the positions of the maxima shift towards higher 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 is not observed in interactions at and at . Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured spectra above progressively decouple from hydrodynamical-model calculations. For higher values of , models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the dependence of the ratio.
- Received 29 July 2013
DOI:https://doi.org/10.1103/PhysRevLett.111.222301
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© 2013 CERN, for the ALICE Collaboration