Resummation of relativistic corrections to heavy quarkonium +\,γ production at Z factory

Cross sections of the heavy quarkonium production process e⁺e⁻→ H + γ at the c.m. energy of Z⁰-boson resonance are calculated at leading order in αₛ with relativistic corrections resummed within the framework of nonrelativistic QCD (NRQCD). S- and P-wave charmonia and bottomonia are considered. For J/ψ(Υ) production, the result of vector-meson-dominance (VMD) approach is also given. Relativistic contributions to charmonium production are of the same magnitude as next-to-leading order QCD corrections, decreasing cross section 20-30%. Relativistic corrections to bottomonium production are negligible, not exceeding 2%.