The dominance of high-spin two-particle one-hole transitions in (p,π−) reactions

Abstract Measurements of broad-range momentum spectra for (p, π − ) reactions near threshold on a number of target nuclei with 13⩽A⩽92 have revealed a striking and systematic selectivity for one or a few low-lying states In the residual nuclei. We propose that the dominant transitions lead to high-spin stretched (or nearly stretched) two-particle one-hole states (with respect to the target-nucleus ground-state configurations), as favored by a two-nucleon pion production mechanism. Experiments which might confirm this explanation and possible future applications of the (p, π − ) selectivity are discussed.