The reactions π~-p→ηn and γp→ηp are investigated within a dynamical coupled-channels model of meson production reactions in the nucleon resonance region. The meson-baryon channels included are πN, ηN, π△, σN, and ρN. The direct η-photoproduction process is studied within a formalism based on a chiral constituent quark model approach, complemented with a one-gluon-exchange mechanism, to take into account the breakdown of the SU(6) O(3) symmetry. In the models search, the following known nucleon resonances are embodied: S_(11)(1535), S_(11)(1650), P_(11)(1440), P_(11)(1710), P_(13)(1720), D_(13)(1520), D_(13)(1700), D_(15)(1675), and F_(15)(1680). Data for the π~-p→ηn reaction from threshold up to a total center-of-mass energy of W ≈ 2 GeV are satisfactorily reproduced. For the photoproduction channel, two additional higher mass known resonances, P_(13)(1900) and F_(15)(2000), are also considered. However, reproducing the data for γp→ηp requires, within our approach, two new nucleon resonances, for which we extract mass and width.
multichannel scattering meson production baryon resonances
B.Saghai J.Durand B.Julia-Diaz HE Jun T.-S.H.Lee T.Sato
Institut de Recheche sur les lois Fondamentales de lUnivers,DSM/Irfu,CEA-Saclay,91191 Gif-sur-Yvett Excited Baryon Analysis Center (EBAC),Thomas Jefferson National Accelerator Facility,Newport News,Vi Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China Excited Baryon Analysis Center (EBAC),Thomas Jefferson National Accelerator Facility,Newport News,Vi Excited Baryon Analysis Center (EBAC),Thomas Jefferson National Accelerator Facility,Newport News,Vi