Amplitude analysis and branching fraction measurement of $J/\ddot{I}ˆ\to \hat{I}›\bar{\hat{I}}{\pounds }^0\hat{I}\cdot +c.c$

Abstract

Based on a sample of $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events collected with the BESIII detector, a partial-wave analysis of $J/\ddot{I}ˆ\to \hat{I}›{\overline{\hat{I}\pounds }}^0\hat{I}\cdot +c.c$ is performed for the first time. The dominant contributions are found to be excited $\hat{I}›$ states with $J^P=1/2^{-}$ and $J^P=1/2^{+}$ in the $\hat{I}\cdot \hat{I}›$ mass spectra. The measured masses and widths are $M=1668.8\pm 3.1\pm 21.2$ MeV/$c^2$ and $\hat{I}“=52.7\pm 4.2\pm 17.8$ MeV for the $\hat{I}›(1670)$, and $M=1881.5\pm 16.5\pm 20.3$ MeV/$c^2$ and $\hat{I}“=82.4\pm 18.2\pm 8.9$ MeV for the $\hat{I}›(1810)$, respectively. The branching fraction is determined to be $\mathcal{B}(J/\ddot{I}ˆ\to \hat{I}›{\overline{\hat{I}\pounds }}^0\hat{I}\cdot +c.c)$ = $(3.44\pm 0.11\pm 0.13)\times 10^{-5}$. The first uncertainties are statistical and the second systematic.