Singlet-to-triplet ratio in the deuteron breakup reaction pd→pnp at 585 MeV

Available experimental data on the exclusive pd→pnp reaction at 585 MeV show a narrow peak in the proton–neutron final-state interaction region. It was supposed previously, on the basis of a phenomenological analysis of the shape of this peak, that the final spin-singlet pn state provided about one third of the observed cross section. By comparing the absolute value of the measured cross section with that of pd elastic scattering using the Fäldt–Wilkin extrapolation theorem, it is shown here that the pd→pnp data can be explained mainly by the spin-triplet final state with a singlet admixture of a few percent. The smallness of the singlet contribution is compatible with existing pN→pNπ data and the one-pion exchange mechanism of the pd→pnp reaction.