In the framework of the kT​-factorization, the prompt production of
ηc​ mesons at the LHC conditions is studied. Our consideration is based on
the off-shell amplitudes for hard partonic subprocesses and on the
nonrelativistic QCD (NRQCD) formalism for the formation of bound states. We try
two latest parametrizations for noncollinear, or transverse momentum dependent
(TMD) gluon densities derived from the Catani-Ciafaloni-Fiorani-Marchesini
(CCFM) equation. We use the values of the nonperturbative matrix elements
obtained from a combined fit of the ηc​ and J/ψ differential cross
sections. Finally, we show an universal set of parameters that provides a
reasonable simultaneous description for all of the available data on the prompt
J/ψ and ηc​ production at the LHC.Comment: 5 pages, 2 figures, 3 table