Measurement of the branching fraction of $J/\ddot{I}ˆ\to \ddot{I}\ddot{I}€$ at KEDR

Abstract

We present the study of the decay $J/\ddot{I}ˆ\to \ddot{I}\ddot{I}€$. The results are based on of 5.2~million $J/\ddot{I}ˆ$ events collected by the KEDR detector at the VEPP-4M collider. The branching fractions are measured to be $\B(J/ψ\rightarrow ρπ) = \big(2.072\pm 0.017 \pm 0.062 \big)\cdot 10^{-2}$ and $\B(J/ψ\rightarrow π^+π^-π^0) = \big(1.878 \pm 0.013 \pm 0.051 \big)\cdot 10^{-2}$, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.