First Measurement of the Absolute Branching Fraction of $\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3$

Abstract

We apply a tag-and-probe method to precisely measure the absolute branching fraction of the decay $\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3$ with the BESIII experiment at BEPCII. Starting with a large initial sample of $2712.4\pm 14.3$ million $\ddot{I}ˆ(3686)$ events, a sample of 0.16 million $\hat{I}{\cdot }_c$ events are tagged via the golden channel $\ddot{I}ˆ(3686)\to \ddot{I}{€}^0{h}_c$, $h_c\to {\hat{I}}^3\hat{I}{\cdot }_c$, effectively avoiding interference effects. The absolute branching fraction of $\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3$ is measured for the first time to be $\mathcal{B}(\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3)=(2.45\pm 0.48_{stat.}\pm 0.09_{syst.})\times 10^{-4}$. Using the world average value of the total width of the $\hat{I}{\cdot }_c$, the partial decay width of $\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3$ is calculated to be $\hat{I}“(\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3)=(7.48\pm 1.48_{stat.}\pm 0.30_{syst.})\mathrm{keV}$.

11 pages, 3 figures