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

Abstract

The beam-helicity asymmetry in associated electroproduction of real photons, $ep\to eγπN$, 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, $ep\to eγπ^0 p$ and $ep\to eγπ^+ n$, from a data set collected with a recoil detector. All asymmetry amplitudes are found to be consistent with zero.

17 pages, 4 figures, (minor changes wit respect to previous arXiv version)