Multichannel treatment of resonant reactions using the quasiparticle method

Abstract

A multichannel resonant reaction formalism is introduced using the quasiparticle method of Grassberger and Sandhas. Contrary to Feshbach's projection operator approach our method can, without difficulty, take the Pauli principle correctly into account and treat rearrangement processes. The direct transition amplitude and the closed channel bound states obey exact onedimensional integral equations. The generalized potentials occurring in them are calculable via an iteration scheme which should rapidly converge in most cases of physical interest. Thus the level shift and level width are finally expressed by accessible quantities.