New extraction of the Re+e- elastic scattering cross-section ratio based on a simplified phenomenological hard two-photon-exchange correction approach

In this work, we present a prediction of the positron-proton and electron-proton elastic scattering cross-section ratio Re+e- based on a new phenomenological parametrization of the hard two-photon-exchange (TPE) corrections to electron-proton elastic scattering cross section σR. The TPE parametrization proposed in this work is rather simple, as it only requires the use of suitable global fits of both the Rosenbluth magnetic GM, and the true magnetic GM form factors, or alternatively, the electric form factors GE and GE. We compare our results to recent extractions, and world's data on Re+e- with emphasis mainly on the kinematics range of the recent direct measurements from the CLAS, VEPP-3, and OLYMPUS experiments. With the proper choice of GM and GM parametrizations, and while our results are in generally good agreement with Re+e- measurements taken at high ϵ points and for all Q2 range, they agree remarkably well, within the error bands of the predictions, with Re+e- measurements taken at low-ϵ points for Q2=1.0 and 1.5(GeV/c)2, where emphasis should be placed for evidence of hard TPE correction. Finally, we believe that the assumption that hard TPE corrections could account for the discrepancy on the proton's form factors ratio μpGE/GM is still an open question as more measurements of Re+e- are clearly needed for Q2>2.1(GeV/c)2, in the region where the discrepancy is significant.