New measurement of Sigma beam asymmetry for eta meson photoproduction on the proton

Ajaka, J.; Anghinolfi, M.; Bellini, V.; Berrier, G.; Bocquet, J. P.; Breuer, M.; Calvat, P. M.; Capogni, M.; Casano, L. E.; Castoldi, M.; Ciciani, L.; Corvisiero, P.; D'Angelo, A.; Didelez, J. P.; Di Salvo, R.; Djalali, C.; Duval, M. A.; Frascaria, R.; Gervino, Gianpiero; Ghio, F.; Girard, P.; Girolami, B.; Guinault, E.; Hoffmann Rothe, P.; Hourany, E.; Kilvington, I.; Kouznetsov, V.; Lapik, A.; Sandri, P. L.; Moricciani, D.; Morlet, M.; Nedorezov, V.; Nicoletti, L.; Perrin, C.; Rebreyend, D.; Renard, F.; Ripani, M.; Rosier, L.; Rossi, P.; Roudot, F.; Russew, T.; Sanzone, M.; Schaerf, C.; Sperduto, M. L.; Sudov, A.; Taiuti, M.; Turinge, A.; Van de, J.; Zucchiatti, A.

We present new Sigma beam asymmetry data for eta meson photoproduction on the proton, using a novel tagged, laser backscattered, linearly polarized photon beam up to 1.1 GeV. The data show large, positive asymmetries, at all incident photon energies. In addition to the S-11(1535) and D-13(1520) resonances necessary to reproduce the cross sections, P-13(1720) and D-15(1675) "four stars" resonances contribute to the Sigma observable, but cannot reproduce the strong forward asymmetries measured at energies higher than 900 MeV.