Radiative decay ofJψintoη(1430)and nearby states

Radiative decays of $\frac{J}{\psi }$ into $K^{+}{K}^{-}{\pi }^0$, $K_S^0{K}^{\pm }{\pi }^{\mp }$, $\eta {\pi }^{+}{\pi }^{-}$, and $\rho \gamma$ have been studied in the $\eta \mathrm{}\left(1430\right)\mathrm{}$ mass range from the $8.6\times {10}^6\frac{J}{\psi }\text{'}\mathrm{s}$ produced in the DM2 experiment at the Orsay $e^{+}{e}^{-}$ storage ring (DCI). The $\eta \mathrm{}\left(1430\right)\mathrm{}$ is observed in both $K_S^0{K}^{\pm }{\pi }^{\mp }$ and $K^{+}{K}^{-}{\pi }^0$ channels. A three-body decay-angular analysis of the whole signal supports a $J^P=0^{-}$ assignment. A substantial $K{K}^{*}\mathrm{}\left(892\right)\mathrm{}$ dynamics is present whereas the significance of the $a_0\mathrm{}\left(980\right)\mathrm{}\pi$ contribution cannot be evaluated. The $\eta \mathrm{}\left(1430\right)\mathrm{}$ is not observed in the $\eta \pi \pi$ channel which shows a peak in the $\frac{f_1\mathrm{}\left(1285\right)\mathrm{}}{\eta \mathrm{}\left(1275\right)\mathrm{}}$ mass range and a new state at 1398 MeV/${\mathit{c}}^2$, ≃50 MeV/${\mathit{c}}^2$ wide. An $a_0\mathrm{}\left(980\right)\mathrm{}\pi$ intermediate-state contribution is present at least in the latter state. Finally, the low-statistics $\rho \gamma$ final state gives no evidence of $\eta \mathrm{}\left(1430\right)\mathrm{}$ production.