Next-to-leading-order study of J/ψ angular distributions in e+e−→ J/ψ + ηc, χcJ at s≈ 10.6 GeV

A bstract In this paper, we present a detailed next-to-leading-order (NLO) study of J/ψ angular distributions in e + e − → J/ψ + η c , χ cJ ( J = 0 , 1 , 2) within the nonrelativistic QCD factorization (NRQCD). The numerical NLO expressions for total and differential cross sections, i.e., dσ d cos θ = A + B cos 2 θ , are both derived. With the inclusion of the newly-calculated QCD corrections to A and B , the α θ (= B/A ) parameters in J/ψ + χ c 0 and J/ψ + χ c 1 are moderately enhanced, while the magnitude of α θJ/ψ + χc 2 is significantly reduced; regarding the production of J/ψ + η c , the α θ value remains unchanged. By comparing with experiment, we find the predicted α θJ/ψ + ηc is in good agreement with the B elle measurement; however, α θJ/ψ + χc 0 is still totally incompatible with the experimental result, and this discrepancy seems to hardly be cured by proper choices of the charm-quark mass, the renormalization scale, and the NRQCD matrix elements.