Speaker
Description
Electron-nucleon scattering at beam energies ~few 100 MeV explores the large-distance dynamics in the baryon sector of QCD, governed by chiral pion-nucleon interactions and the excitation of the Delta isobar. We discuss what specific features could be studied by combining positron and electron-nucleon scattering in this energy range. This includes:
(i) Chiral dynamics in low-Q2 nucleon form factors and peripheral charge/magnetization densities; (ii) Single-spin asymmetries from two-photon exchange in low-energy electron/positron-nucleon scattering; (iii) Charged/neutral pion electroproduction and Delta isobar excitation using positrons (Re/Im ratio). Such measurements could be considered with the planned low-energy positron beam at Jefferson Lab.
