JOURNAL OF HIGH ENERGY PHYSICS, vol.2018, no.4, 2018 (SCI-Expanded)
The p(T)-differential production cross section of prompt Lambda(+)(c) charmed baryons was measured with the ALICE detector at the Large Hadron Collider (LHC) in pp collisions at root s = 7 TeV and in p-Pb collisions at root s(NN) = 5.02 TeV at midrapidity. The Lambda(+)(c) and (Lambda) over bar (-)(c) were reconstructed in the hadronic decay modes Lambda(+)(c) -> pK(-)pi(+), Lambda(+)(c)-> pK(S)(0)) and in the semileptonic channel Lambda(+)(c) -> e(+)nu(e)Lambda (and charge conjugates). The measured values of the Lambda(+)(c)/D-0 ratio, which is sensitive to the c-quark hadronisation mechanism, and in particular to the production of baryons, are presented and are larger than those measured previously in different colliding systems, centre-of-mass energies, rapidity and p(T) intervals, where the Lambda(+)(c) production process may differ. The results are compared with the expectations obtained from perturbative Quantum Chromodynamics calculations and Monte Carlo event generators. Neither perturbative QCD calculations nor Monte Carlo models reproduce the data, indicating that the fragmentation of heavy-flavour baryons is not well understood. The first measurement at the LHC of the Lambda(+)(c) nuclear modification factor, R-ppb, is also presented. The R-ppb is found to be consistent with unity and with that of D mesons within the uncertainties, and consistent with a theoretical calculation that includes cold nuclear matter effects and a calculation that includes charm quark interactions with a deconfined medium.