Λ c+ production in Pb–Pb collisions at s NN =5.02 TeV

A measurement of the production of prompt Lambda+c baryons in Pb–Pb collisions at √sNN=5.02TeV with the ALICE detector at the LHC is reported. The Lambda+c and anti-Lambda−c were reconstructed at midrapidity (|y| <0.5) via the hadronic decay channel Lambda+c→pK0S (and charge conjugate) in the transverse momentum and centrality intervals 6 <12GeV/c and 0–80%. The Lambda+c/D0 ratio, which is sensitive to the charm quark hadronisation mechanisms in the medium, is measured and found to be larger than the ratio measured in minimum-bias pp collisions at √s=7TeV and in p–Pb collisions at √sNN=5.02TeV. In particular, the values in p–Pb and Pb–Pb collisions differ by about two standard deviations of the combined statistical and systematic uncertainties in the common pT interval covered by the measurements in the two collision systems. The Lambda+c/D0 ratio is also compared with model calculations including different implementations of charm quark hadronisation. The measured ratio is reproduced by models implementing a pure coalescence scenario, while adding a fragmentation contribution leads to an underestimation. The Lambda+cnuclear modification factor, RAA, is also presented. The measured values of the RAA of Lambda+c, D+s and non-strange D mesons are compatible within the combined statistical and systematic uncertainties. They show, however, a hint of a hierarchy (RD0AA