First observations of $h_c \to$ hadrons

TL;DR

This paper reports the first observation of three hadronic decay modes of the $h_c$ charmonium state, using a large dataset from the BESIII detector, and measures their branching fractions.

Contribution

First observation of three $h_c$ hadronic decay modes with measured branching fractions and significance levels, expanding understanding of $h_c$ decay channels.

Findings

First-time observation of $h_c o p ar{p} ho$, $h_c o ho ho ho$, and $h_c o 2( ho ho) ho$ decays.

Measured branching fractions for these decays with statistical and systematic uncertainties.

Established upper limits for two other decay modes.

Abstract

Based on $(4.48 \pm 0.03) \times 10^{8}$ $\psi(3686)$ events collected with the BESIII detector, five $h_c$ hadronic decays are searched for via process $\psi(3686) \to \pi^0 h_c$. Three of them, $h_c \to p \bar{p} \pi^+ \pi^-$, $\pi^+ \pi^- \pi^0$, and $2(\pi^+ \pi^-) \pi^0$ are observed for the first time, with statistical significances of 7.4$\sigma$, $4.9\sigma$, and 9.1$\sigma$, and branching fractions of $(2.89\pm0.32\pm0.55)\times10^{-3}$, $(1.60\pm0.40\pm0.32)\times10^{-3}$, and $(7.44\pm0.94\pm1.56)\times10^{-3}$, respectively, where the first uncertainties are statistical and the second systematic. No significant signal is observed for the other two decay modes, and the corresponding upper limits of the branching fractions are determined to be $B(h_c \to 3(\pi^+ \pi^-) \pi^0)<8.7\times10^{-3}$ and $B(h_c \to K^+ K^- \pi^+ \pi^-)<5.8\times10^{-4}$ at 90% confidence level.