The Extraction of the Near-Threshold J/ψ-Meson Photoproduction Reaction from Experimental Electroproduction Data

The use of a method developed in the CLAS collaboration (Jefferson Lab, USA) to extract events of quasi-real photoproduction on nuclei from experimental data of electroproduction, as applied to the reaction of near-threshold photoproduction of the J/psi-meson is described in this paper. Experimental data of electroproduction on a liquid hydrogen target, which was obtained on CLAS12 experimental setup, were analyzed. The photoproduction of e(+)e(-) pairs were studied from ep -> p'e(+)e(-)X reaction, where e(+)e(-) lepton pair is formed during the decay of the vector meson or virtual photon, p' is the recoil proton. The method of selection of fully exclusive of the final state e(+)e(-)p'(e') reaction is given, where the lepton pair, e(+)e(-) is formed during the decay of the J/psi-meson, and the kinematics of the scattered electron, e', is derived from the analysis of the missing momentum of the system.