Next-to-leading-order QCD corrections to [formula omitted] production at the LHC

Abstract

In this work, we calculate the next-to-leading-order (NLO) QCD corrections to the process p + p → J / ψ + γ via the color-singlet mechanism at the LHC. The results show that the partial cross section ( p t J / ψ > 3 GeV and | y J / ψ , γ | < 3 ) is enhanced by a factor of about 2.0, and the differential cross section can be enhanced by two orders of magnitude in the large transverse momentum region of J / ψ . Furthermore, the polarization of J / ψ changes from transverse polarization at leading-order to longitudinal polarization at NLO. For the inclusive J / ψ hadroproduction, it is known that the color-octet contributions are one order of magnitude larger than the color-singlet contribution, and the polarization distribution is dominated by the color-octet behavior at NLO. In contrast, for J / ψ + γ production the color-singlet contribution is of the same order as the color-octet contribution, and the polarization distribution arises from both the color-singlet and color-octet. Therefore, measurements of J / ψ production associated with a direct photon at the hadron collider could be an important supplement to testify the theoretical framework treating with the heavy quarkonium. In addition, an NLO QCD correction to ϒ + γ production at the LHC is also presented in this Letter.