Global analysis of the experimental data on $\chi_c$ meson   hadroproduction
  We carry out a global analysis of the experimental data on the $\chi_c$ production cross section and the ratio $\sigma(\chi_{c2})/\sigma(\chi_{c1})$ at the LHC and the Tevatron. The related long-distance matrix elements (LDMEs) at both leading order (LO) and next-to-leading order (NLO) in the QCD coupling constant are renewed. We also present the transverse momentum distribution of the $\chi_c$ production cross section and the ratio $\sigma(\chi_{c2})/\sigma(\chi_{c1})$ for several experimental conditions and find that NLO predictions agree with all sets of experimental data. By contrast, at LO, one cannot explain all the data with a unique value of the color-octet LDME. A brief analysis of the nonrelativistic QCD scale dependence of the cross sections shows that, for the conditions we are concerned with in this paper, the dependence can be almost totally absorbed into the LDME. 
Hong-Fei Zhang, Ling Yu, Shao-Xiang Zhang, Lan Jia
hep-ph