Precision measurement of the branching fractions of $\hat{I}{\cdot }^{\prime }$ decays

Abstract

Based on a sample of $(1310.6\pm 7.0)\times 10^{6}J/\ddot{I}ˆ$ events collected with the BESIII detector, we present measurements of $J/\ddot{I}ˆ$ and $\hat{I}{\cdot }^{\prime }$ absolute branching fractions using the process $J/\ddot{I}ˆ\to {\hat{I}}^3\hat{I}{\cdot }^{\prime }$. By analyzing events where the radiative photon converts into an $e^{+}{e}^{-}$ pair, the branching fraction for $J/\ddot{I}ˆ\to {\hat{I}}^3\hat{I}{\cdot }^{\prime }$ is measured to be $(5.27\pm 0.03\pm 0.05)\times 10^{-3}$. The absolute branching fractions of the five dominant decay channels of the $\hat{I}{\cdot }^{\prime }$ are then measured independently for the first time and are determined to be $\mathcal{B}(\hat{I}{\cdot }^{\prime }\to {\hat{I}}^3\ddot{I}{€}^{+}\ddot{I}{€}^{-})$ = (29.90$\pm$0.03$\pm$0.55)%, $\mathcal{B}(\hat{I}{\cdot }^{\prime }\to \hat{I}\cdot \ddot{I}{€}^{+}\ddot{I}{€}^{-})$ = (41.24$\pm$0.08$\pm$1.24)%, $\mathcal{B}(\hat{I}{\cdot }^{\prime }\to \hat{I}\cdot \ddot{I}{€}^0\ddot{I}{€}^0)$ = (21.36$\pm$0.10$\pm$0.92)%, $\mathcal{B}(\hat{I}{\cdot }^{\prime }\to {\hat{I}}^3\ddot{I}‰)$ = (2.489$\pm$0.018$\pm$0.074)%, and $\mathcal{B}(\hat{I}{\cdot }^{\prime }\to {\hat{I}}^3{\hat{I}}^3)$ = (2.331$\pm$0.012$\pm$0.035)%, where the first uncertainties are statistical and the second systematic.

7 pages, 1 figures