Single and double pion production from 800 MeV proton-proton collisions

The three-body final-state reaction of charged single-pion production, $pp\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\mathrm{pn}$, and that for charged double-pion production, $pp\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}pp$, have been studied at ${T}_{P}=800$ MeV by measuring the momentum spectra for ${\ensuremath{\pi}}^{+}$ and ${\ensuremath{\pi}}^{\ensuremath{-}}$ emitted from proton-proton collisions. The momentum spectra for single-pion production are fit with the peripheral model calculations of VerWest, and a similar model by one of us is discussed. The spectra for double-pion production follow an extrapolation of the Lindenbaum and Sternheimer model from higher energies toward threshold. This result is in disagreement with the results of Cochran et al.