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QCD corrections to J/psi production via color octet states at Tevatron and LHC

The remarkable discrepancy between theory and data on the p_t distribution of J/psi polarization in the process pp -> J/psi+X has been standing as a puzzle for a long time. Our early work indicates that if only considering the color-singlet state, NLO corrections may drastically change the distribution, but are not sufficient to accommodate the data. The color-octet intermediate state was suggested to make up the gap. Therefore a direct motivation is to evaluate if the NLO corrections to the J/psi production via a color-octet can indeed remedy the problem. Unfortunately, our results show that even the NLO corrections to both color-singlet and octet states are accounted, the data cannot be understood yet in the framework of the present theory, but there, as observed, still a small window remains, namely a P-wave octet might substantially contribute.