Evidence for a $\pi \eta$ Resonance at 970 MeV Produced in $K^{-}p\to \Lambda {\pi }^{+}{\pi }^{-}$ MM at 3.9, 4.6, and 5.0 GeV/c

Evidence is presented for the existence of a boson resonance ($\delta$) with $M=970\mathrm{}\pm 15$ MeV and $\Gamma <~50$ MeV produced in the reaction $K^{-}p\to {\Sigma }^{+}\mathrm{}\left(1385\right)\mathrm{}{\delta }^{-}$, ${\delta }^{-}\to {\pi }^{-}\eta$. By studying the ${\delta }^{-}$ produced in association with ${\Sigma }^{+}\mathrm{}\left(1385\right)\mathrm{}$, we are able to rule out possible kinematic effects as a source of the enhancement in our data. We give upper limits to other decay modes such as $2\pi$, $3\pi$, and $K\overline{K}$.