Two-photon exchange contribution to elastic $e^{-}$-proton scattering: Full dispersive treatment of $\ddot{I}€N$ states and comparison with data

Abstract

We evaluate the two-photon exchange correction to the elastic electron-proton scattering cross section within a dispersive framework. Besides the elastic contribution, we account for all $\ddot{I}€N$ intermediate state contributions using the phenomenological MAID fit as an input. We develop a novel method for the analytical continuation of the two-photon exchange amplitudes into the unphysical region and generalize our previous work to the momentum transfer region $0.064{\mathrm{GeV}}^2\lesssim Q^2\lesssim 1{\mathrm{GeV}}^2$. We compare our results with recent OLYMPUS, CLAS and VEPP-3 data as well as with empirical fits and estimates in the forward angular region.

43 pages, 21 figures, version published in Phys. Rev. D 96, 096001 (2017)