Production of Λc baryons at the LHC within the kT-factorization approach and independent parton fragmentation picture

We calculate the cross section for the production of D mesons and Lambda(c) baryons in proton-proton collisions at the LHC. The cross section for production of c (c) over bar pairs is calculated within the k(T)-factorization approach with the Kimber-Martin-Ryskin unintegrated gluon distributions obtained on the basis of modern collinear gluon distribution functions. We show that our approach well describes the D-0, D+, and D-s experimental data. We try to understand recent ALICE and LHCb data for Lambda(c) production with the c -> Lambda(c) independent parton fragmentation approach. The Peterson fragmentation functions are used. The integral(c ->Lambda c) fragmentation fraction and epsilon(Lambda)(c) parameter for c -> Lambda(c) are varied. As a control plot we show the transverse momentum distributions of different species of D mesons assuming standard values of the f(c -> D) fragmentation fractions known from the literature. Although one can agree with the ALICE data using the standard estimation of model uncertainties, one cannot describe simultaneously the ALICE and the LHCb data with the same set of parameters. The fraction integral(c ->Lambda c) necessary to describe the ALICE data is much larger than the average value obtained from e(+)e(-) or ep experiments. No drastic modification of the shape of the fragmentation function is allowed by the new ALICE and LHCb data for Lambda(c) production. We also discuss a possible dependence of the Lambda(c)/D-0 baryon-to-meson ratio on rapidity and transverse momentum as recent observations by the ALICE and LHCb collaborations seem to suggest. Three different effects are considered: the value of the epsilon(Lambda)(c) parameter in the Peterson fragmentation function for c -> Lambda(c), a kinematical effect related to the hadronization prescription, and a possible feed-down from higher charmed-baryon excitations. It seems very difficult, if not impossible, to understand the ALICE data within the considered independent parton fragmentation scheme.