Using $(27.12\pm0.14) \times 10^{ 8}$ $\psi(2S)$ events collected by the BESIII detector operating at BEPCII, we search for the decay $\eta_c(2S)\to p\bar{ p}$ via the process $\psi(2S)\to \gamma\eta_c(2S)$, and only find a signal with a significance of $1.7\,\sigma$. The upper limit of the product branching fraction at the 90% confidence level is determined to be $\mathcal{ B}(\psi(2S)\to \gamma\eta_c(2S))\times \mathcal{ B}(\eta_c(2S)\to p\bar{ p})<2.4\times 10^{ -7}$. The branching fractions of $\chi_{ cJ}\to p\bar{ p}~(J=0,1,2)$ are also measured to be $\mathcal{ B}(\chi_{ c0}\to p\bar{ p})=(2.51\pm0.02\pm0.08)\times 10^{ -4}$, $\mathcal{ B}(\chi_{ c1}\to p\bar{ p})=(8.16\pm0.09\pm0.25)\times 10^{ -4}$, and $\mathcal{ B}(\chi_{ c2}\to p\bar{ p})=(8.33\pm0.09\pm0.22)\times 10^{ -4}$, where the first uncertainty is statistical and the second systematic.
Categories: hep-ex