Pseudoscalar Quarkonium+gamma Production at NLL+NLO accuracy

Understand

We consider the exclusive pseudoscalar heavy-quarkonium (eta_{b,c}) production in association with a photon at future lepton colliders where the collider energies of O(10^2) GeV are far greater than the quarkonium mass.

• At these energies, the logarithm of mass to collision energy becomes increasingly large hence its resummation becomes particularly important.
• By making use of the light-cone-distribution factorization formula, we resum the logarithms up to next-to-leading-logarithmic accuracy (NLL) that corresponds to order-alpha_s accuracy.
• We combine the resummed result with a known fixed-order result at next-to-leading order (NLO) such that both resummed-logarithmic terms and non-logarithmic terms are included at the same order in alpha_s.