The helicity-dependent observable E for the reaction γd→ηn(p) with a spectator proton was recently measured by the A2 Collaboration at MAMI in Mainz. The data were interpreted as further evidence for a narrow resonance with spin and parity JP=1/2+ (P11 wave). However, a full partial wave analysis without any narrow resonance leads to an excellent description of the data, imposing a narrow resonance with the properties suggested by the A2 Collaboration leads to a significant deterioration of the fit quality: there is no need for a narrow resonance.
@article{arxiv.1701.06387,
title = {Is there a narrow $N(1685)$?},
author = {A. V. Anisovich and V. Burkert and E. Klempt and V. A. Nikonov and A. V. Sarantsev and U. Thoma},
journal= {arXiv preprint arXiv:1701.06387},
year = {2017}
}