Resonances Produced in the Reactionπ−p→π−π−π+pat 8 GeV/c

Abstract

A study has been made of the reaction ${\pi }^{-}p\to {\pi }^{-}{\pi }^{-}{\pi }^{+}p$ at an incident momentum of 8.05 GeV/c. We find this reaction to be very peripheral and dominated by production of the ${\rho }^0$ and the $N^{*++}\mathrm{}\left(1236\right)\mathrm{}$. The $A_2$ meson and an additional ${\pi }^{-}{\rho }^0$ enhancement at 1190 MeV are observed. The spins and parities of these resonances are examined with particular attention to the effect of the type and amount of background assumed. There has been much interest in higher-mass boson resonances; we here examine an enhancement in the $3\pi$ mass distribution at 1610 MeV which appears to decay primarily to ${\pi }^{-}{f}^0$. An enhancement in the ${\pi }^{-}{\pi }^{+}p$ system near 1400 MeV is observed. We find that this enhancement cannot be explained by a Deck-type production mechanism, and conclude that the enhancement is due to production of the Roper resonance, the $N^{*}\mathrm{}\left(1400\right)\mathrm{}$.