Resonance wave functions and resonance parameters from the coupled-channel method

Abstract

Abstract The behaviour of the many-particle scattering wave function in the vicinity of a resonance is studied in the frame of the shell-model approach to nuclear reactions. The possibility of defining a meaningful wave function for a resonance is discussed. It is exhibited that the resonance wave function can be described, like in the bound state case, by configuration mixing coefficients which, however, are complex and correspond to single-particle resonances as well as to bound states embedded in the continuum. It is shown how the configuration mixing coefficients and the parameters of the resonances (total width, complex partial widths, resonance energy) can be extracted from the coupled-channel method. Two methods are proposed. Their flexibility is emphasized and exhibited in the example of the main peak of the giant dipole resonance in 40 Ca. The results are compared with those obtained from a standard bound state description of that resonance.