Study of the process e(+) e(-) -> p(p)over-bar via initial state radiation at BESIII

Abstract

The Born cross section for the process e(+) e(-)-> p (p) over bar is measured using the initial state radiation technique with an undetected photon. This analysis is based on datasets corresponding to an integrated luminosity of 75 fb(-1), collected with the BESIII detector at the BEPCII collider at center of mass energies between 3.773 and 4.600 GeV. The Born cross section for the process e(+) e(-)-> p (p) over bar and the proton effective form factor are determined in the p (p) over bar invariant mass range between 2.0 and 3.8 GeV/c(2) divided into 30 intervals. The proton form factor ratio (vertical bar G(E)vertical bar/vertical bar G(M)vertical bar) is measured in 3 intervals of the p (p ) over bar invariant mass between 2.0 and 3.0 GeV/c(2).