Prompt charmonia production and polarization at LHC in the NRQCD with kT-factorization. II. χc mesons

In the framework of the k(T)-factorization approach, the production of prompt psi(2S) mesons in pp collisions at the LHC energies is studied. Our consideration is based on the off-shell amplitudes for hard partonic subprocesses g*g* -> chi(cJ) and nonrelativistic QCD formalism for bound states. The transverse-momentum-dependent (unintegrated) gluon densities in a proton were derived from the Ciafaloni-Catani-Fiorani-Marchesini evolution equation or, alternatively, were chosen in accordance with the Kimber-Martin-Ryskin prescription. Taking into account both color-singlet and color-octet contributions, we deduce the corresponding nonperturbative long-distance matrix elements from the fits to the latest ATLAS data on chi(c1) and chi(c2) transverse-momentum distributions at root s = 7 TeV. We find that these distributions at small and moderate p(T) are formed mainly by the color-singlet components. We successfully described the data on the relative production rates sigma(chi(c2))/sigma(chi(c1)) presented by the ATLAS, CMS, and LHCb Collaborations. We find that the fit points to unequal wave functions of chi(c1) and chi(c2) states.