η-production on the proton via electromagnetic and hadronic probes

• 作 者: B.Saghai J.Durand B.Julia-Diaz
• 机 构: Institut de Recheche sur les lois Fondamentales de l'Univers,Excited Baryon Analysis Center (EBAC),
• 出 处: 中国物理C（英文版）
• 发表日期: 2004年期
• 关键词: multichannel scattering meson production baryon resonances
• 基金项目: %%;Consolider Ingenio

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.