J/ψ Polarization at Hadron Colliders in Nonrelativistic QCD

With nonrelativistic QCD factorization, we present a full next-to-leading order computation of the polarization observable for J/psi production at hadron colliders including all important Fock states, i.e., S-3(1)[1,8], S-1(0)[8], and P-3(J)[8]. We find the P-3(J)[8] channel contributes a positive longitudinal component and a negative transverse component, so the J/psi polarization puzzle may be understood as the transverse components canceling between the S-3(1)[8] and P-3(J)[8] channels, which results in mainly the unpolarized (even slightly longitudinally polarized) J/psi. This may give a possible solution to the long-standing J/psi polarization puzzle. Predictions for J/psi polarization at the LHC are also presented.