The production cross section of prompt $\mathrm{ \Lambda_{ c}^{ +}}$ charm baryons was measured with the ALICE detector at the LHC at midrapidity in proton-proton (pp) and proton-lead (p-Pb) collisions at a centre-of-mass energy per nucleon pair of $\sqrt{ s_\mathrm{ NN}} = 5.02$ TeV. The $\mathrm{ \Lambda_{ c}^{ +}}$ and $\rm { \overline{ \Lambda}{ }_c^-}$ baryons were reconstructed in the hadronic decay channels $\rm \Lambda_{ c}^{ +} \rightarrow p K^{ -}\pi^{ +}$ and $\rm \Lambda_{ c}^{ +}\to p K^{ 0}_{ S}$ and respective charge conjugates. The measured differential cross sections as a function of transverse momentum ($p_{ \rm T}$) and the $p_{ \rm T}$-integrated $\mathrm{ \Lambda_{ c}^{ +}}$ production cross section in pp and in p-Pb collisions are presented. The $\mathrm{ \Lambda_{ c}^{ +}}$ nuclear modification factor ($R_\mathrm{ pPb}$), calculated from the cross sections in pp and in p-Pb collisions, is presented and compared with the $R_\mathrm{ pPb}$ of D mesons. The $\mathrm { \Lambda_{ c}^{ +}}/\mathrm { D^0}$ ratio is also presented and compared with the light-flavour baryon-to-meson ratios p$/\pi$ and $\Lambda /\mathrm { K^0_S}$, and measurements from other LHC experiments. The results are compared to predictions from model calculations and Monte Carlo event generators.
Categories: nucl-ex hep-ex