QCD corrections to J/ψ production via color-octet states at the Tevatron and LHC

The Next-To-Leading-Order (NLO) QCD corrections to J/ψ production via S-wave color-octet states at the Tevatron and LHC are calculated. There are only slight changes to the transverse momentum pt distributions of J/ψ production and polarization. By fitting the pt distribution of J/ψ production measured at Tevatron with both color-singlet and color-octet included, we obtain the color-octet matrix elements at NLO. The resulting pt distribution of J/ψ polarization still does not coincide with the experimental data. Therefore, we have reached the conclusion that the large discrepancy of J/ψ polarization between theory and experimental data cannot be solved by just including NLO corrections within non-relativistic QCD framework and then one has to explore solution from different angles.