Two-photon exchange in electron deuteron scattering

TL;DR

This paper investigates two-photon exchange effects in elastic electron-deuteron scattering, revealing the structure of generalized form factors and their impact on reaction observables beyond the Born approximation.

Contribution

It identifies the six generalized form factors involved and clarifies that only three combinations influence the cross section, analyzing two-photon exchange diagrams and their effects on observables.

Findings

Two-photon exchange includes interactions with same and different nucleons.

Only three linear combinations of six form factors affect the cross section.

Two-photon exchange impacts reaction observables and polarization measurements.

Abstract

It is shown that the amplitude of elastic ed scattering beyond Born approximation contains six generalized form factors, but only three linearly independent combinations of them (generalized charge, quadrupole and magnetic form factors) contribute to the reaction cross section in the second order perturbation theory. We examine two-photon exchange and find that it includes two types of diagrams, when two virtual photons interact with the same nucleon and when the photons interact with different nucleons.We discuss contribution of the two-photon exchange in reaction observables, generalized \mathcal A and \mathcal B structure functions and tensor polarization of the deuteron.