Search for the radiative transitions $\psi (3770)\to \gamma {\eta }_c$ and $\gamma {\eta }_c(2S)$

Abstract

By using a 2.92 fb${}^{-1}$ data sample taken at $\sqrt{s}=3.773$ GeV with the BESIII detector operating at the BEPCII collider, we search for the radiative transitions $\psi (3770)\to \gamma {\eta }_c$ and $\gamma {\eta }_c(2S)$ through the hadronic decays ${\eta }_c({\eta }_c(2S))\to K_S^0{K}^{\pm }{\pi }^{\mp }$. No significant excess of signal events above background is observed. We set upper limits at a 90% confidence level for the product branching fractions to be $\mathcal{B}(\psi (3770)\to \gamma {\eta }_c)\times \mathcal{B}({\eta }_c\to K_S^0{K}^{\pm }{\pi }^{\mp })<1.6\times 10^{-5}$ and $\mathcal{B}(\psi (3770)\to \gamma {\eta }_c(2S))\times \mathcal{B}({\eta }_c(2S)\to K_S^0{K}^{\pm }{\pi }^{\mp })<5.6\times 10^{-6}$. Combining our result with world-average values of $\mathcal{B}({\eta }_c({\eta }_c(2S))\to K_S^0{K}^{\pm }{\pi }^{\mp })$, we find the branching fractions $\mathcal{B}(\psi (3770)\to \gamma {\eta }_c)<6.8\times 10^{-4}$ and $\mathcal{B}(\psi (3770)\to \gamma {\eta }_c(2S))<2.0\times 10^{-3}$ at a 90% confidence level.

10 pages, 4 figures

References in corpus (4)

• Exotic and excited-state radiative transitions in charmonium from lattice QCD
• Measurements of the cross sections for $e^{+}{e}^{-}\to \mathrm{hadrons}$ at 3.650, 3.6648, 3.773 GeV and the branching fraction for $\psi (3770)\to \mathrm{non}-D\bar{D}$
• Measurements of the braching fractions for psi(3770)--> D0D0-bar,D+D-,DD-bar$ and the resonance parameters of psi(3770) and psi(2S)
• Evidence for η_{c}(2S) in ψ(3686) \to γK_{S}^{0}K^{\pm}π^{\mp}π^{+}π^{-}