Enhanced production of $Λ_{c}$ in proton-proton collisions at the LHC

Abstract

We calculate cross section for production of $D$ mesons and $Λ_c$ baryons in proton-proton collisions at the LHC. The cross section for production of $c \bar c$ pairs is calculated within $k_T$-factorization approach with the Kimber-Martin-Ryskin unintegrated gluon distributions. 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 $Λ_c$ production with the $c \to Λ_c$ independent parton fragmentation approach. The Peterson fragmentation functions are used. The $f_{c \to Λ_c}$ fragmentation fraction and $\varepsilon_{c}^Λ$ parameter for $c \to Λ_c$ are varied. Although one can agree with the ALICE data using standard estimation of model uncertainties one cannot describe simultaneously the ALICE and the LHCb data with the same set of parameters. The fraction $f_{c \to Λ_c}$ neccessary to describe the ALICE data is much larger than the average value obtained from $e^+ e^-$ or $e p$ experiments. It seems very difficult, if not impossible, to understand the ALICE data within the considered independent parton fragmentation scheme.