QCD radiative corrections to χcJ production at hadron colliders

To clarify the outstanding problem in charmonium production that existing theories cannot explain the observed cross sections of chi(cJ)(J = 0, 1, 2) and ratio R-chi c = sigma(chi c2)/sigma(chi c1) approximate to 0.75(in contrast to the spin counting value 5/3) at the Tevatron, we study the complete next-to-leading order radiative corrections in nonrelativistic QCD, and find next-to-leading order contributions of P-3(J)vertical bar 1 vertical bar are more important than leading order at high p(T), and P-3(1)vertical bar 1 vertical bar decreases slower than P-3(2)vertical bar 1 vertical bar, implying a natural explanation for the R-chi c puzzle. By fitting R-chi c, the predicted cross sections of chi(cJ) are found to agree with data. The result indicates coloroctet contribution is crucially needed, thus providing a unique test for heavy quarkonium production mechanisms. Feed-down contributions of chi(cJ) to prompt J/psi production are estimated to be substantial, about 30%-40% at p(T) = 20 GeV. Production of chi(cJ)(J = 0, 1, 2) at the LHC is also predicted.