4-states of16O in the region of 19 MeV excitation

Abstract
A three-state isospin-mixing model is fitted to available data on pion scattering and nucleon pick-up relevant to the 4- states of 16O at 17.79, 18.98 and 19.80 MeV. An excellent fit to all data is obtained, and the state descriptions are shown to be consistent with inelastic proton scattering measurements. The 18.98 MeV state is predominantly 1p-1h T=1, while the other two states have significant isospin mixing and 3p-3h admixtures.