Beam-helicity asymmetry in associated electroproduction of real photons $ep\to e{\hat{I}}^3\ddot{I}€N$ in the $\hat{I}”$-resonance region

Abstract

The beam-helicity asymmetry in associated electroproduction of real photons, $ep\to e{\hat{I}}^3\ddot{I}€N$, in the $\hat{I}”$(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, $ep\to e{\hat{I}}^3\ddot{I}{€}^{0}p$ and $ep\to e{\hat{I}}^3\ddot{I}{€}^{+}n$, 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)