Amplitude analysis of the ${\chi }_{c1}\to \eta {\pi }^{+}{\pi }^{-}$ decays

M. Ablikim, M. N. Achasov, S. Ahmed +430

Using $448.0\times 10^6$~$\psi (3686)$ events collected with the BESIII detector, an amplitude analysis is performed for $\psi (3686)\to \gamma {\chi }_{c1}$, ${\chi }_{c1}\to \eta {\pi }^{+}{\pi }^{-}$ decays. The most domin…