Analysis of the [formula omitted] reaction at 5.7 GeV/ c

Abstract

From 63 760 four pronged events we have selected 10 960 events of the p pπ +π − final state. We have studied baryon resonances production and the associated production of Δ(1236) Δ(1236) isobars. We find (48.5 ± 2.6)% of Δ ++ Δ ++ and (4.5 ± 0.5)% of Δ 0 Δ 0 . Study of the various mass spectra shows that they are essentially described by the introduction of Δ ++ ( Δ ++ ) production. Introduction of the strong t dependence of the Δ ++ ( Δ ++ ) changes this description only slightly. A study of the interaction radius of the p π system reveals a best value of r = 1.6 ± 0.4 fm. Bumps observed in the p π + π − + c.c. system at 1450 and 1690 MeV when treated as resonances give rates of (4.0 ± 0.4)% and (4.5 ± 0.4)% respectively. We arrive at the conclusion that the reaction p p → p pπ +π − at 5.7 GeV/ c proceeds almost entirely via the production of baryon resonances.