Complete study on polarization of γ(nS) hadroproduction at QCD next-to-leading order

By applying the nonrelativistic quantum chromodynamics factorization formalism to γ（1 S,2 S,3 S） hadroproduction,a complete analysis of the polarization parameters λ;,λ;,and λ;for the production is presented at QCD next-to-leading order.With the long-distance matrix elements extracted from experimental data for the production rate and polarization parameter λ;of γ hadroproduction,our results provide a good description of the measured parameters λ;and λ;in both the helicity and Collins-Soper frames.In our calculations,the frame invariant parameter ■ is consistent in the two frames.Finally,we mention that there are discrepancies between the available experimental data and corresponding theoretical predictions for ■.