A study of pion absorption by 16O using realistic interactions - I. Two-nucleon emission following bound-pion absorption

Matrix element of the Galilean invariant non-relativistic reduction of the pseudoscalar-pseudovector interaction has been calculated assuming the reaction to be a direct process with bound π-being absorbed by a correlated pair of nucleons. The Hartree-Fock wavefunctions obtained with the unitary-model-operator approach starting with the realistic nucleon-nucleon interaction have been used for π-capturing nucleon pair in the initial state. The calculations have been done with and without antisymmetrising the initial state wave-function of the pion absorbing pair. For the final state nucleon-nucleon interaction has been taken into account. The strong π-nucleus interaction together with the Coulomb interaction with the finite nuclear size on the bound pion wavefunction is taken into account. Angular distributions of the emitted nucleon-pair, the branching ratios and the total absorption rates are calculated for 16O with and without antisymmetrisation effect. The calculated results are compared with the experimental and other theoretical work. (author)