Partial-wave analysis of the low-massπ+π+π−system produced by incidentπ+mesons at 13GeVc

Results are presented of a spin-parity analysis of the (${\pi }^{+}{\pi }^{+}{\pi }^{-}$) system formed opposite a proton by incident $13-\frac{\mathrm{GeV}}{c} {\pi }^{+}$ mesons in a bubble chamber exposure of 750 000 pictures in hydrogen. Relative proportions of the contributing $J^P$ states are given for ${\left(3\mathrm{}\pi \right)}^{+}$ masses between 0.9 and 1.4 $\frac{\mathrm{GeV}}{c^2}$ and their dependence on $t_{\pi }^{\prime }\to 3\pi$ is also discussed. Measurement of the phase between interfering production amplitudes gives information about the resonance status of the $A_1$, $A_2$ mesons. The method employs the University of Illinois three-body partial-wave analysis program.