Extraction of $\sigma_{TT}$ for Proton, Neutron, Deuteron and $^3$He from Quasi-real Photon Scattering

Abstract

We report on an extraction of the polarized photoproduction cross-section for the proton, deuteron, neutron and $^3$He, obtained by extrapolating electron scattering data to the real photon point. The data are from the Jefferson Lab E97-110 ($^3$He) and CLAS EG4 (proton and deuteron) experiments. Information on the neutron is extracted from the deuteron or $^3$He data using the weak binding approximation. Comparing with data obtained with real photons, we find that while the proton results agree, our results on the deuteron and the neutron exhibit a larger strength in the $\Delta(1232)$ region, and are more consistent with isospin symmetry when compared with the proton results.