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

The three-body final-state reaction of charged single-pion production, $pp\to {\pi }^{+}\mathrm{pn}$, and that for charged double-pion production, $pp\to {\pi }^{-}{\pi }^{-}pp$, have been studied at $T_P=800\mathrm{}$ MeV by measuring the momentum spectra for ${\pi }^{+}$ and ${\pi }^{-}$ 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.