Prompt charmonia hadroproduction in High Energy Factorization with tree-level NLO corrections

Abstract

We consider prompt $J/\psi$, $\chi_{cJ}$ and $\eta_c$ production in high energy $pp$ collisions in the framework of non-relativistic QCD. We apply high-energy factorization with taking into account tree-level next-to-leading order corrections to the production amplitudes. Using several CCFM-evolved gluon densities in the proton and a previously proposed matching scheme to merge the leading and higher-order contributions, we extract the long-distance matrix elements for the entire charmonium family from a simultaneous fit to available LHC data. We provide predictions for the transverse momentum spectra and relative production rates $\sigma(\psi^\prime)/\sigma(J/\psi)$ and $\sigma(\chi_{cJ})/\sigma(J/\psi)$ and find them to be in good agreement with the LHC data within the theoretical and experimental uncertainties across a wide kinematic region. We demonstrate that taking into account the tree-level NLO corrections improves the global description of the data.