Partial wave analysis of the π−π−π+ and π−π0π0 systems and the search for a JPC=1−+ meson

A partial wave analysis (PWA) of the ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ and ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ systems produced in the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}(3\ensuremath{\pi}{)}^{\ensuremath{-}}p$ at $18\text{ }\text{ }\mathrm{GeV}/c$ was carried out using an isobar model assumption. This analysis is based on 3.0 M ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ events and 2.6 M ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ events and shows production of the ${a}_{1}(1260)$, ${a}_{2}(1320)$, ${\ensuremath{\pi}}_{2}(1670)$, and ${a}_{4}(2040)$ resonances. Results of detailed studies of the stability of partial wave fits are presented. An earlier analysis of 250 K ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ events from the same experiment showed possible evidence for a ${J}^{PC}={1}^{\ensuremath{-}+}$ exotic meson with a mass of $\ensuremath{\sim}1.6\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ decaying into $\ensuremath{\rho}\ensuremath{\pi}$. In this analysis of a higher statistics sample of the $(3\ensuremath{\pi}{)}^{\ensuremath{-}}$ system in two charged modes we find no evidence of an exotic meson.