Prompt inclusive production of $J/ψ$, $ψ'$ and $χ_{c}$ mesons at $\sqrt{s}$ $=$ $68.5$ $GeV$ energy within NRQCD $k_t$-factorization approach

Abstract

We discuss prompt production of $J/ψ$ mesons in proton-proton collisions at the $\sqrt{s}$ $=$ $68.5$ $GeV$ energy within NRQCD $k_t$-factorization approach using different unintegrated gluon distributions functions (UGDFs). We include both direct color-singlet production ($g g \to J/ψg$) as well as a feed-down from $χ_c \to J/ψγ$ and $ψ' \to J/ψX$ decays. The production of the decaying mesons $χ_c$ or $ψ'$ is also calculated within NRQCD $k_t$-factorization approach. Differential distributions in rapidity and transverse momentum of $J/ψ$ are calculated and compared with experimental data of the LHCb collaborations. The LHCb fixed target data allow to test UGDFs in a new range of $x$.