Nucleon resonances within a dynamical coupled-channels model of pi N and gamma N reactions

Understand

The nucleon resonances are investigated within a dynamical coupled-channels model of pi N and gamma N reactions up to the invariant mass W = 2 GeV.

• The meson-baryon (MB) channels included in the calculations are MB = pi N, eta N, K Lambda, K Sigma, and pi pi N that has pi Delta, rho N, and sigma N resonant components.
• The meson-baryon amplitudes T_{M'B',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'B',MB} derived from phenomenological Lagrangian, and (b) vertex interactions N* --> MB for describing the transition of a bare excited nucleon state N* to a channel MB.
• The parameters of v_{M'B',MB} are mainly constrained by the fit to the data of pi N --> pi N in the low energy region up to W =1.4 GeV.