Pion exchange interaction in the γp → pe+e− reaction

Abstract

The [Formula: see text] interference has been studied in the dilepton invariant mass distribution spectra in the photonuclear reaction, but that is not done for the gamma-nucleon reaction. In the recent past, the [Formula: see text] invariant mass distribution spectrum in the [Formula: see text] reaction, i.e., [Formula: see text] reaction, was measured at Jefferson Laboratory to look for the [Formula: see text] interference in the multi-GeV region. To study the mechanism of this reaction, the differential cross section of the [Formula: see text] invariant mass distribution is calculated in the quoted energy region. The reaction is assumed to proceed as [Formula: see text]; [Formula: see text], where [Formula: see text] denotes a vector meson, i.e., either [Formula: see text] or [Formula: see text] meson. The photoproduction of the vector meson is described by the Vector Meson Dominance (VMD) model which consists of diagonal and off-diagonal processes. The diagonal process is described as [Formula: see text]. The low-energy [Formula: see text] meson photoproduction data is well described by the off-diagonal process which is illustrated as [Formula: see text]. The reaction [Formula: see text] proceeds due to one pion exchange interaction. The differential cross-sections of the [Formula: see text] reaction due to the above processes of VMD model are compared, and the significance of the pion exchange interaction is investigated in the energy region of [Formula: see text] beam available at Jefferson Laboratory.