Coherent pion production and the excited states of5He

Abstract
A cluster model is developed to relate the amplitudes for the 4He(p, pi +)5He (1985) reaction to those for 3He(p, pi +)4He. The low-lying states of 5He are described in terms of separable potentials acting in the n-4He system. The model reproduces well the 5He excitation energy spectra observed in the reaction and also the shape of the angular distribution of the produced pion, both close to threshold and at high energies.