2013/05/31 by H. Kamano, Satoshi Nakamura, S. X. Nakamura +3
Physics and Astronomy · #Nuclear physics research studies #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1103/physrevc.88.035209
published as Phys. Rev. C 88, 035209 (2013) · 83 pages, 47 figures. Typos are corrected and references are added. Version to appear in PRC
arxiv created 2013/09/27 · openalex publication_date 2013/09/27 · arxiv updated 2013/09/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
The nucleon resonances are investigated within a dynamical coupled-channels model of \ensuremathπN and \ensuremathγN reactions up to the invariant mass W=2 GeV. The meson-baryon (MB) channels included in the calculations are MB= \ensuremathπN, \ensuremathηN, K\ensuremathΛ, K\ensuremathΣ, and \ensuremathπ\ensuremathπN that has \ensuremathπ\ensuremathΔ, \ensuremathρN, and \ensuremathσN resonant components. The meson-baryon amplitudes T_M^\ensuremath'B^\ensuremath',MB(W) are calculated from solving a set of coupled-channels integral equations defined by an interaction Hamiltonian consisting of (a) meson-exchange interactions v_M^\ensuremath'B^\ensuremath',MB derived from phenomenological Lagrangian and (b) vertex interactions N*\ensuremath→MB for describing the transition of a bare excited nucleon state N* to a meson-baryon channel MB. The parameters of v_M^\ensuremath'B^\ensuremath',MB are mainly constrained by the fit to the data of \ensuremathπN\ensuremath→\ensuremathπN in the low-energy region up to W=1.4 GeV. The bare masses of N* and the N*\ensuremath→MB parameters are then determined in simultaneous fits to the data of \ensuremathπN\ensuremath→\ensuremathπN up to W=2.3 GeV and those of \ensuremathπN\ensuremath→\ensuremathηN,K\ensuremathΛ,K\ensuremathΣ and \ensuremathγN\ensuremath→\ensuremathπN,\ensuremathηN,K\ensuremathΛ,K\ensuremathΣ up to W=2.1 GeV. The pole positions and residues of nucleon resonances are extracted by analytically continuing the meson-baryon amplitudes T_M^\ensuremath'B^\ensuremath',MB(W) to the complex Riemann energy surface. From the extracted residues, we have determined the N*\ensuremath→\ensuremathπN,\ensuremathγN,\ensuremathηN,K\ensuremathΛ,K\ensuremathΣ transition amplitudes at resonance poles. We compare the resonance pole positions from our analysis with those given by the Particle Data Group and the recent coupled-channels analyses by the J"ulich and Bonn-Gatchina groups. Four results agree well only for the first N* in each spin-parity-isospin (JP,I) channel. For higher mass states, the number of states and their resonance positions from four results do not agree well. We discuss the possible sources of the discrepancies and the need of additional data from new hadron facilities such as the Japan Proton Accelerator Research Complex.