The γn → ηn quasi-free cross section reveals a resonant structure at W ~ 1.675 GeV. This structure may be a manifestation of a baryon resonance. A priori its propreties, the possibly narrow width and the strong photocoupling to the neutron, look surprising. This structure may also signal the existence of a narrow state.
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V. Kuznetsov, O. Bartalini, V. Bellini, M. Castoldi, A. D’Angelo, J. P. Didelez, R. Di Salvo, A. Fantini, D. Franco, G. Gervino, F. Ghio, B. Girolami, A. Giusa, M. Guidal, E. Hourany, R. Kunne, A. Lapik, P. Levi Sandri, D. Moricciani, L. Nicoletti, C. Randieri, N. Rudnev, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge.
NSTAR 2005, Proceedings of Workshop on the Physics of Excited Nucleons, Florida State University, Tallahassee (USA), 12-15 October 2005. World Scientific Publishing Co. Pte. Ltd., June 2006, pp. 336-339, doi: 10.1142/9789812773333_0045.
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