Coupled-channels study of theπ−p→ηnprocess

Abstract

The reaction π − p → ηn is 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 , σ N, and ρN. The nonresonant meson-baryon interactions of the model are derived from a set of Lagrangians by using a unitary transformation method. One or two excited nucleon states in each of S, P , D, and F partial waves are included to generate the resonant amplitudes. Data of the π − p → ηn reaction from threshold up to a total center-of-mass energy of about 2 GeV are satisfactorily reproduced and the roles played by the following nine nucleon resonances are investigated: . The reaction mechanism and the predicted ηN scattering length are discussed.

Poles as the only true resonant-state signals extracted from a worldwide collection of partial-wave amplitudes using only one, well controlled pole-extraction method

“…The unpublished set [43] in a way supersedes the former 2008 analysis [38] where unpleasantly large change of πN elastic partial waves was needed to accommodate for the second channel. We have analyzed both sets of amplitudes wandering whether a significant change in poles between the two is found.…”

Dynamical coupled-channels study of meson production reactions from EBAC@JLab

“…The πN → ηN reaction: It is known that for the π − p → ηn reaction underlying inconsistencies exist among data sets from different experimental groups [4]. In our analysis, we follow the strategy described in Ref.…”

“…In our analysis, we follow the strategy described in Ref. [4] for how to (middle panels), and π − p → K 0 Λ 0 (right panels). The data are from Refs.…”

“…In this model, the reaction amplitudes T α,β (p, p ′ ; E) are calculated from the following coupled-channels integral equations, [3] and πN → ηN [4] up to W = 2 GeV, and γN → πN [5] and N(e, e ′ π)N [6] up to W = 1.6 GeV. Then, the model was applied to πN → ππN [7] and γN → ππN [8] to predict cross sections and examine consistency of the coupled-channels framework.…”

Nuclear reactions at intermediate energies

“…The effective methods that are used to describe the dynamics of meson production reactions, include explicitly the baryon resonance states whose properties are extracted by comparing the predictions of the theory with the experimental data [9][10][11][13][14][15][16][17]. However, for a reliable realization of this goal, a model is required that can analyze different reactions over the entire energy range using a single Lagrangian density, which generates all non-resonance contributions from Born, u-and t-channel contributions without introducing new parameters.…”