Theoretical uncertainties in exclusive electroproduction of S-wave heavy quarkonia

In this work, we revise the conventional description of J/ ψ(1 S) , Υ (1 S) , ψ^′(2 S) and Υ ^′(2 S) elastic photo- and electroproduction off a nucleon target within the color dipole picture and carefully study various sources of theoretical uncertainties in calculations of the corresponding electroproduction cross sections. For this purpose, we test the corresponding predictions using a bulk of available dipole cross section parametrisations obtained from deep inelastic scattering data at HERA. Specifically, we provide the detailed analysis of the energy and hard-scale dependencies of quarkonia yields employing the comprehensive treatment of the quarkonia wave functions in the Schrödinger equation based approach for a set of available c- c¯ and b- b¯ interquark interaction potentials. Besides, we quantify the effect of Melosh spin rotation, the Q²-dependence of the diffractive slope and an uncertainty due to charm and bottom quark mass variations.