Beam-helicity asymmetry in associated electroproduction of real photons ep → eγπN in the Δ-resonance region

Abstract

The beam-helicity asymmetry in associated electroproduction of real photons, ep → eγπN, in the Δ(1232)-resonance region is measured using the longitudinally polarized Hera positron beam and an unpolarized hydrogen target. Azimuthal Fourier amplitudes of this asymmetry are extracted separately for two channels, ep → eγπ0 p and ep → eγπ+ n, from a data set collected with a recoil detector. All asymmetry amplitudes are found to be consistent with zero. © 2014 The Author(s).