Azimuthal asymmetries in J/?-photon production at the EIC

We calculate azimuthal asymmetries in back-to-back production of J/psi and a photon in electron-proton scattering process at the future electron-ion collider using the transverse momentum dependent parton distribution (TMD) factorization framework. We consider the cases where the proton is unpolarized or transversely polarized. For the formation of J/psi, nonrelativistic QCD is used. We find that the cross section gets contributions from only one color octet state. As a result, the azimuthal modulations become independent of the long-distance matrix elements, and thus can be used to probe, in particular the gluon TMDs which are dominant in this kinematics. We show estimates of the upper bounds of different azimuthal asymmetries using the positivity bounds on TMDs. In addition, we show an estimate of asymmetries using the Gaussian parametrization of the TMDs.

Automated summary

In this study, we calculate the azimuthal asymmetries in back-to-back production of J/psi and a photon in electron-proton scattering process at the future electron-ion collider using the transverse momentum dependent parton distribution (TMD) factorization framework. We consider both unpolarized and transversely polarized proton cases. The formation of J/psi is described using nonrelativistic QCD, and we find that the cross section is contributed by only one color octet state. This results in azimuthal modulations that are independent of long-distance matrix elements, making them suitable for probing the dominant gluon TMDs in this kinematics. We provide estimates of the upper bounds of different azimuthal asymmetries using positivity bounds on TMDs, as well as an estimate of the asymmetries using the Gaussian parametrization of the TMDs.