# Branching fraction measurements of $\psi(3686) \to \gamma \chi_{cJ}$

## TL;DR

This paper reports precise measurements of the branching fractions for $ o ext{gamma} ext{chi}_{cJ}$ decays of $ ext{psi}(3686)$ using a large data sample, improving the accuracy of these fundamental charmonium transitions.

## Contribution

The study provides the most precise measurements to date of $ ext{psi}(3686)$ radiative decay branching fractions to $ ext{chi}_{cJ}$ states, including product and individual branching fractions.

## Key findings

- Branching fractions for $ ext{psi}(3686) o ext{gamma} ext{chi}_{cJ}$ measured with improved precision.
- Product branching fractions for $ ext{psi}(3686) o ext{gamma} ext{chi}_{cJ}$ and $ ext{chi}_{cJ} o ext{gamma} J/ ext{psi}$ determined.
- Branching fractions of $ ext{chi}_{cJ} o ext{gamma} J/ ext{psi}$ updated with new measurements.

## Abstract

Using a sample of 106 million $\psi(3686)$ decays, the branching fractions of $\psi(3686) \to \gamma \chi_{c0}, \psi(3686) \to \gamma \chi_{c1}$, and $\psi(3686) \to \gamma \chi_{c2}$ are measured with improved precision to be $(9.389 \pm 0.014 \pm 0.332)\,\%$, $(9.905 \pm 0.011 \pm 0.353)\,\% $, and $(9.621 \pm 0.013 \pm 0.272)\,\% $, respectively, where the first uncertainties are statistical and the second ones are systematic. The product branching fractions of $\psi(3686) \to \gamma \chi_{c1}, \chi_{c1} \to \gamma J/\psi$ and $\psi(3686) \to \gamma \chi_{c2}, \chi_{c2} \to \gamma J/\psi$ and the branching fractions of $\chi_{c1} \to \gamma J/\psi$ and $\chi_{c2} \to \gamma J/\psi$ are also presented.