Measurement of the branching fraction of $J/\psi\rightarrow\rho\pi$ at KEDR

TL;DR

This paper reports a precise measurement of the branching fraction of the decay $J/\psi \rightarrow \rho\pi$ using data from the KEDR detector, improving the accuracy over previous measurements.

Contribution

The study provides the most precise measurement to date of the $J/\psi \rightarrow \rho\pi$ branching fraction based on 5.2 million events.

Findings

Branching fraction $J/\psi \rightarrow \rho\pi$ measured as (2.072 ± 0.017 ± 0.062)×10⁻².

Branching fraction $J/\psi \rightarrow \pi^+\pi^-\pi^0$ measured as (1.878 ± 0.013 ± 0.051)×10⁻².

Results are more precise than previous measurements.

Abstract

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