Precision measurements of branching fractions for $\ddot{I}{ˆ}^{\prime }\to \ddot{I}{€}^{0}J\ddot{I}ˆ$ and $\hat{I}\cdot J\ddot{I}ˆ$

Abstract

We present a precision study of the $\psip\toπ^0 J/ψ$ and $\hat{I}\cdot J/\ddot{I}ˆ$ decay modes. The measurements are obtained using $106\times 10^6$ $\ddot{I}{ˆ}^{\prime }$ events accumulated with the BESIII detector at the BEPCII $\ee$ collider operating at a center-of-mass energy corresponding to the $\psip$ mass. We obtain $\mathcal{B}(\psip\toπ^0 J/ψ)=(1.26\pm0.02{\rm (stat.)}\pm0.03{\rm (syst.)})\times 10^{-3}$ and $\mathcal{B}(\psip\toηJ/ψ)=(33.75\pm0.17{\rm (stat.)}\pm0.86{\rm (syst.)})\times 10^{-3}$. The branching fraction ratio $R=\frac{\mathcal{B}(\psip\toπ^0 J/ψ)}{\mathcal{B}(\psip\toηJ/ψ)}$ is determined to be $(3.74\pm 0.06(stat.)\pm 0.04(syst.))\times 10^{-2}$. The precision of these measurements of $\mathcal{B}(\psip\toπ^{0} J/ψ)$ and $R$ represent a significant improvement over previously published values.

four figures, 12 pages