Speaker
Description
The transverse single-spin asymmetry in inclusive electron-nucleon scattering, e + N(S_T) -> e’ + X, represents a pure two-photon exchange observable and is of fundamental interest for exploring higher-order QED effects in electron scattering. We compute this observable in the resonance region, where excitation of Delta isobars occurs in both intermediate and final states. We employ a novel theoretical method based on the large-Nc limit of QCD, which allows us to consistently combine nucleon and Delta states and predict the elastic, inelastic, and inclusive spin-dependent cross section. Our results aim at disentangling the different contributions of nucleon and Delta states organizing them according to their 1/Nc scaling. The case of the target single spin asymmetry will be discussed in detail. Our predictions could be tested in future measurements of electron nucleon scattering with polarized targets in the few-GeV energy range. Such experiments would complement earlier measurements of the inclusive single-spin asymmetry in the DIS regime (JLab, HERMES) and allow one to study the unknown dependence of two-photon exchange dynamics on the energy/momentum of the probe.
Primary authors: GOITY, Jose (Hampton University, Jefferson Lab); WEISS, Christian (Jefferson Lab); WILLEMYNS, Cintia (University of Mons)