Improved measurement of the branching fraction of $h_c\to \gamma {\eta }^{\prime }/\eta$ and search for $h_c\to \gamma {\pi }^0$

Abstract

The processes $h_c\to \gamma P(P={\eta }^{\prime },\eta ,{\pi }^0)$ are studied with a sample of $(27.12\pm 0.14)\times 10^8$ $\psi (3686)$ events collected by the BESIII detector at the BEPCII collider. The decay $h_c\to \gamma \eta$ is observed for the first time with the significance of $9.0\sigma$, and the branching fraction is determined to be $(3.77\pm 0.55\pm 0.13\pm 0.26)\times 10^{-4}$, while $\mathcal{B}(h_c\to \gamma {\eta }^{\prime })$ is measured to be $(1.40\pm 0.11\pm 0.04\pm 0.10)\times 10^{-3}$, where the first uncertainties are statistical, the second systematic, and the third from the branching fraction of $\psi (3686)\to {\pi }^0{h}_c$. The combination of these results allows for a precise determination of $R_{h_c}=\frac{\mathcal{B}(h_c\to \gamma \eta )}{\mathcal{B}(h_c\to \gamma {\eta }^{\prime })}$, which is calculated to be $(27.0\pm 4.4\pm 1.0)\%$. The results are valuable for gaining a deeper understanding of $\eta -{\eta }^{\prime }$ mixing, and its manifestation within quantum chromodynamics. No significant signal is found for the decay $h_c\to \gamma {\pi }^0$, and an upper limit is placed on its branching fraction of $\mathcal{B}(h_c\to \gamma {\pi }^0)<5.0\times 10^{-5}$, at the 90$\%$ confidence level.

References in corpus (10)

• The Precision Monte Carlo Event Generator KK For Two-Fermion Final States In e+e- Collisions
• Coherent Exclusive Exponentiation For Precision Monte Carlo Calculations
• Mixing and Decay Constants of Pseudoscalar Mesons
• Quark structure of pseudoscalar mesons
• Combined estimation for multi-measurements of branching ratio
• ${\pi }^0$-$\eta$-${\eta }^{\prime }$ mixing from $V\to P\gamma$ and $P\to V\gamma$ decays
• Revisiting the radiative decays $J/\psi \to \gamma {\eta }^{(\prime )}$ in perturbative QCD
• Revisiting the $P$-wave charmonium radiative decays $h_c\to \gamma {\eta }^{(\prime )}$ with relativistic corrections
• Radiative decays of $h_c$ to the light mesons ${\eta }^{(\prime )}$: A perturbative QCD calculation
• Study on the radiative decays of $h_c$ via intermediate meson loops model

Cited by in corpus (2)

• Amplitude Analysis of the Isospin-Violating Decay $J/\psi \to \gamma \eta {\pi }^0$
• Observation of Charmonium $h_c$ Radiative Decays to Multiple Light Hadrons and the Tensor State $f_2(1270)$