Production of theΔ++in the reactionpp→pπ+nat 800 MeV

Abstract

Kinematically complete data for the reaction $\mathrm{pp}\to p{\pi }^{+}n$ at 800 MeV have been accumulated at four proton lab angles (15°, 20°, 25°, and 30°) where the cross section $\frac{d^5\sigma }{d{p}_{1}d{\Omega }_{1}d{\Omega }_2}$ is dominated by ${\Delta }^{++}$ production. The data, spanning four momentum transfers $t_{{\Delta }^{++}}$ between 0.07 and 0.3 (GeV/c)${}_{}{}^2{}_{}{}^{},\mathrm{h}\mathrm{a}\mathrm{v}\mathrm{e}$ been compared to the predictions of a pion and $\rho$ exchange model with various baryonic intermediate states. The best agreement between the theoretical and experimental cross sections was obtained with the form factor range parameters ${\Lambda }_{\pi }=0.78\mathrm{}$ GeV/c and ${\Lambda }_{\rho }=1.8\mathrm{}$ GeV/c. The integrated $\mathrm{pp}\to n{\Delta }^{++}$ cross section was calculated to be 13.4 mb, which, in agreement with isospin predictions of the isobar model, accounts for 75% of the estimated experimental $\mathrm{pp}\to N\Delta$ cross section of 19±3 mb.