Towards higher-order calculations of quarkonia production with $$k_T$$-factorization: P-wave charmonia

Abstract

AbstractInclusive P-wave charmonia production in hadronic collisions at high energies is discussed in the framework of non-relativistic QCD and $$k_T$$ k T -factorization formalism. We present two consistent approaches to merge the usual leading order $$k_T$$ k T -factorization calculations with tree-level next-to-leading order off-shell amplitudes. Using these prescriptions, we extracted long-distance matrix elements for $$\chi _c$$ χ c mesons from a combined fit to available Tevatron and LHC data. In contrast to previous (leading order) calculations, our fits do not rule out the equalness of the color singlet wave functions of $$\chi _{c1}$$ χ c 1 and $$\chi _{c2}$$ χ c 2 states. The extracted values of long-distance matrix elements are employed to analyse the $$\chi _c$$ χ c polarization data reported recently by the CMS Collaboration. Our predictions are in a reasonably good agreement with the Tevatron and LHC measurements within the theoretical and experimental uncertainties.