Measurement of the branching fractions of $\chi_{cJ} \to \pi^{+}\pi^{-}\pi^{0}\pi^{0}$ via $\psi(3686) \to \gamma\chi_{cJ}$

TL;DR

This study measures the branching fractions of $ ext{chi}_{cJ}$ decays into four pions using a large dataset from BESIII, improving precision over previous results and identifying $ ho^+ ho^-$ as the dominant intermediate state.

Contribution

The paper provides the most precise measurements to date of $ ext{chi}_{cJ} o ext{4-pion}$ branching fractions via $ ext{psi}(3686)$ decays, with detailed analysis of intermediate states.

Findings

Branching fractions for $ ext{chi}_{c0,1,2}$ decays are precisely measured.

Dominant intermediate state identified as $ ho^+ ho^-$.

Results significantly improve upon previous measurements.

Abstract

Using $(2712.4\pm14.3)\times 10^6$ $\psi(3686)$ events collected with the BESIII detector operating at BEPCII, the branching fractions of $\chi_{cJ}\to\pi^+\pi^-\pi^0\pi^0$ ($J=0,~1,~2$) are measured via the radiative transition $\psi(3686)\to\gamma\chi_{cJ}$. The results are $\mathcal{B}(\chi_{c0} \to \pi^{+}\pi^{-}\pi^{0}\pi^{0}) = (3.10 \pm 0.01 \pm 0.14) \times 10^{-2}$, $\mathcal{B}(\chi_{c1} \to \pi^{+}\pi^{-}\pi^{0}\pi^{0}) = (1.16 \pm 0.01 \pm 0.05) \times 10^{-2}$, and $\mathcal{B}(\chi_{c2} \to \pi^{+}\pi^{-}\pi^{0}\pi^{0}) = (1.92 \pm 0.01 \pm 0.08) \times 10^{-2}$, where the first uncertainties are statistical and the second systematic. The dominant intermediate states are found to be $\chi_{cJ}\to\rho^+\rho^-$. These results supersede the previous most precise measurements and provide significantly improved precision.