Measurement of the branching ratios $\psi^\prime \to e^+ e^-$, $\psi^\prime \to J/\psi \pi \pi$ and $\psi^\prime \to J/\psi \eta$

TL;DR

This paper reports precise measurements of several decay branching ratios of the $\psi^\prime$ particle, including its decays into electron pairs, J/psi with pions, and J/psi with eta, based on data from the FNAL E835 experiment.

Contribution

The study provides new experimental measurements of $\psi^\prime$ decay branching ratios and the dipion mass distribution, improving the accuracy of these fundamental parameters.

Findings

Measured ${ m B}(\psi^\prime o e^+ e^-)$ as 0.0068 with uncertainties.

Determined ${ m B}(\psi^\prime o J/\psi \pi^+ \pi^-)$ as 0.292.

Presented the dipion mass distribution in $\psi^\prime o J/\psi \pi \pi$ decays.

Abstract

We have measured several branching ratios for $\psi^\prime$ decay using the data collected by FNAL E835 experiment during year 2000, obtaining ${\cal B}(\psi^\prime \to e^+ e^-) = 0.0068\pm0.0001\pm0.0004$, ${\cal B}(\psi^\prime \to J/\psi \pi^+ \pi^-) = 0.292\pm0.005\pm0.018$, ${\cal B}(\psi^\prime \to J/\psi \pi^0 \pi^0) = 0.167\pm0.005\pm0.014$ and ${\cal B}(\psi^\prime \to J/\psi \eta) = 0.028\pm0.002\pm0.002$. We also present a measurement of the dipion mass distribution in the decays $\psi^\prime \to J/\psi \pi \pi$.