First measurement of Λc+ production down to pT=0 in pp and p-Pb collisions at √sNN=5.02 TeV

The production of prompt Lambda(+)(c) baryons has been measured at midrapidity in the transverse momentum interval 0 < pT < 1 GeV/c for the first time, in pp and p-Pb collisions at a center-of-mass energy per nucleon-nucleon collision root s(NN) = 5.02 TeV. The measurement was performed in the decay channel Lambda(+)(c) . pK0 S by applying new decay reconstruction techniques using a Kalman-Filter vertexing algorithm and adopting a machine-learning approach for the candidate selection. The pT -integrated Lambda(+)(c) production cross sections in both collision systems were determined and used along with the measured yields in Pb-Pb collisions to compute the pT -integrated nuclear modification factors RpPb and RAA of Lambda(+)(c) baryons, which are compared to model calculations that consider nuclear modification of the parton distribution functions. The Lambda(+)(c) /D0 baryon-to-meson yield ratio is reported for pp and p-Pb collisions. Comparisons with models that include modified hadronization processes are presented, and the implications of the results on the understanding of charm hadronization in hadronic collisions are discussed. A significant (3.7s) modification of the mean transverse momentum of Lambda(+)(c) baryons is seen in p-Pb collisions with respect to pp collisions, while the pT -integrated Lambda(+)(c) /D0 yield ratio was found to be consistent between the two collision systems within the uncertainties.