Search for $\eta_c(2S)\to p\bar{p}K^+K^-$ and measurement of $\chi_{cJ}\to p\bar{p}K^+K^-$ in $\psi(3686)$ radiative decays

TL;DR

This study searches for the decay $ ext{eta}_c(2S) o par{p}K^+K^-$ and measures branching fractions of $ ext{chi}_{cJ} o par{p}K^+K^-$ in $ ext{psi}(3686)$ radiative decays, finding evidence for the $ ext{eta}_c(2S)$ decay and quantifying related branching ratios.

Contribution

First measurement of $ ext{eta}_c(2S)$ decay to $par{p}K^+K^-$ and detailed branching fraction measurements for $ ext{chi}_{cJ}$ decays in $ ext{psi}(3686)$ radiative processes.

Findings

Evidence for $ ext{eta}_c(2S) o par{p}K^+K^-$ with 3.3$\sigma$ significance.

Branching fraction product for $ ext{psi}(3686) o ext{gamma} ext{eta}_c(2S)$ and $ ext{eta}_c(2S) o par{p}K^+K^-$ is $(1.98\, ext{±}\,0.41_{ ext{stat}}\pm 0.99_{ ext{syst}}) imes 10^{-7}$.

Branching fractions for $ ext{psi}(3686) o ext{gamma} ext{chi}_{cJ}$ and $ ext{chi}_{cJ} o par{p}K^+K^-$ are measured for $J=0,1,2$.

Abstract

A search for $\eta_c(2S)\to p\bar{p}K^+K^-$, together with measurement of branching fractions of $\chi_{cJ(J=0,1,2)}\to p\bar{p}K^+K^-$ in the $\psi(3686) \to \gamma \eta_c(2S)$ and the $\psi(3686) \to \gamma \chi_{cJ}$ radiative decays, is performed with $(2712.4\pm14.3)\times 10^6$ $\psi(3686)$ events collected with the BESIII detector at the BEPCII collider. An evidence for $\eta_c(2S)\to p\bar{p}K^+K^-$ is found, with a significance of $3.3\sigma$. The product branching fraction of $\mathcal{B}[\psi(3686)\to\gamma\eta_c(2S)]\cdot\mathcal{B}[\eta_c(2S)\to p\bar{p}K^+K^-]$ is determined to be $(1.98\mkern 2mu\pm\mkern 2mu0.41_{\text{stat.}}\mkern 2mu\pm\mkern 2mu0.99_{\text{syst.}})\times 10^{-7}$. The product branching fractions of $\mathcal{B}[\psi(3686)\to\gamma\chi_{cJ}]\cdot\mathcal{B}[\chi_{cJ}\to p\bar{p}K^+K^-]$ are measured to be $(2.49\mkern 2mu\pm\mkern 2mu 0.03_{\text{stat.}}\mkern 2mu\pm\mkern 2mu 0.15_{\text{syst.}})\times 10^{-5}$, $(1.83\mkern 2mu \pm\mkern 2mu 0.02_{\text{stat.}}\mkern 2mu \pm\mkern 2mu 0.11_{\text{syst.}})\times 10^{-5}$, and $(2.43\mkern 2mu\pm\mkern 2mu 0.02_{\text{stat.}}\mkern 2mu\pm\mkern 2mu 0.15_{\text{syst.}})\times 10^{-5}$, for $J=0,\ 1$, and 2, respectively.