Faddeev calculations of pμ + p collisions: effect of hyperfine splitting on the cross sections

The Faddeev equations, modified to remove long-range coupling between different channels, are solved in the total-angular-momentum representation for pμ+p collisions. S-wave elastic and hyperfine-transition cross sections are calculated with and without explicit inclusion of the hyperfine splitting ΔE. For hyperfine quenching the simpler approach without hyperfine splitting is found to be adequate at collision energies above about ΔE, but for elastic scattering it does not become adequate until somewhat higher energies. The present cross sections tend to fall in between earlier calculations performed using a large standard adiabatic expansion and those performed using a two-state improved adiabatic expansion, but are closer to the former. (Author)