Coupled-channel dynamics in the reactions πN → πN, ηN, KΛ, KΣ

Abstract

Elastic πN scattering and the world data of the family of reactions π − p → ηn, K 0 Λ, K 0 Σ 0 , K + Σ − , and π + p → K + Σ + are described simultaneously in an analytic, unitary, coupled-channel approach. SU(3) flavor symmetry is used to relate both the t-and the u-channel exchanges that drive the meson-baryon interaction in the different channels. Angular distributions, polarizations, and spin-rotation parameters are compared with available experimental data. Partial-wave amplitudes are determined and the resonance content is extracted from the analytic continuation, including resonance positions and branching ratios, and possible sources of uncertainties are discussed. The results provide the final-state interactions for the ongoing analysis of photo-and electroproduction data.

Reexamination of the role of theΔ*resonances in thepp→nK+Σ+reaction

“…I. This is also in line with the study of the π + p → K + Σ + reaction in different models [25][26][27][28][29][30][31][32][33][34], which usually include only one of the P 31 states. Correspondingly we will consider these two solutions in the π + p → K + Σ + reaction in the following calculation.…”

“…The GWU analysis find one P 31 pole at M = 1771 MeV but assigned it as the ∆ * (1910) resonance due to its BreitWigner mass located at above 2.0 GeV [49]. The Juelich model find a dynamical generated P 31 state around 1750 MeV besides the genuine ∆ * (1910) resonance [25][26][27][28]. However, the ∆ * (1750) is only a one-star state in PDG [37].…”

“…The Juelich model [25][26][27][28] finds that the ∆ * (1620) is dominant in the low en-ergies of this reaction, while the Bonn-Gatchina partial wave analysis identifies the ∆ * (1920) as the most essential contribution [29,30]. The Giessen model with the K-matrix approximation claims the vital role of the ∆ * (1750) at close-threshold range [31][32][33][34].…”

From Extraction of Nucleon Resonances to LQCD

“…It has been observed in Ref. [1] that three such multi-channel analyses [1][2][3] agree well for the N * states with energies below about 1.6 GeV, but disagree very significantly at higher energies. In the first part of this contribution, we use several exactly soluble ππ scattering models to investigate the sources of these differences and discuss how a dynamical approach used in the ANL-Osaka [1] analysis can help reduce the uncertainties in extracting the nucleon resonances.…”

Pion-nucleon scattering in covariant baryon chiral perturbation theory with explicit Delta resonances

“…From the theory side, in order to describe such a fundamental process, dispersion relations for πN scattering have been investigated several decades ago [3][4][5] and many phenomenological models and different approaches have been proposed (see, e.g., refs. [6][7][8][9][10][11][12][13]). Roy-Steiner equations for the pion-nucleon scattering have been also analysed recently [14][15][16][17].…”