Observation of thepππDecay Mode of theN12*(1400)Resonance inppInteractions at 22 GeV/c

Approximately 12 000 four-pronged interactions of 22-GeV/c protons in a hydrogen bubble chamber have been measured. In a sample of 1234 $\mathrm{pp}{\pi }^{+}{\pi }^{-}$ events the final state is dominated by ${\Delta }^{++}\mathrm{}\left(1236\right)\mathrm{}$ production. Approximately 120 of these events are attributed to the $p{\pi }^{+}{\pi }^{-}$ decay of a resonant state with mass 1443 ± 15 MeV and width 100 ± 25 MeV identified with the $N_{\frac{1}{2}}^{}{}_{}{}^{*}\mathrm{}\left(1400\right)\mathrm{}$ resonance. There is also strong evidence for a $p\pi \pi$ enhancement with a central mass value of 1693 MeV.