Measurements of the Mass and Full-Width of the ${\eta }_c$ Meson

Abstract

In a sample of 58 million $J/\psi$ events collected with the BES II detector, the process J/$\psi \to \gamma {\eta }_c$ is observed in five different decay channels: $\gamma K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$, $\gamma {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$, $\gamma K^{\pm }{K}_S^0{\pi }^{\mp }$ (with $K_S^0\to {\pi }^{+}{\pi }^{-}$), $\gamma \varphi \varphi$ (with $\varphi \to K^{+}{K}^{-}$) and $\gamma p\bar{p}$. From a combined fit of all five channels, we determine the mass and full-width of ${\eta }_c$ to be $m_{{\eta }_c}=2977.5\pm 1.0(stat.)\pm 1.2(syst.)$ MeV/$c^2$ and ${\Gamma }_{{\eta }_c}=17.0\pm 3.7(stat.)\pm 7.4(syst.)$ MeV/$c^2$.

arXiv comment9 pages, 2 figures and 4 table. Submitted to Phys. Lett. B

References in corpus (7)

• Partial Wave Analysis of $J/\psi \to \gamma ({\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-})$
• S-D Mixing and Searching for the psi(1P1) State at the Beijing Electron-Positron Coolider
• Study of the Hadronic Decays of χ_c States
• Partial Wave Analysis of $J/\psi \to \gamma (K^{\pm }{K}_S^0{\pi }^{\mp })$
• Measurements of the Mass, total Width and Two-Photon Partila Width of the ${\eta }_c$ Meson
• Partial Wave Analysis of $J/\psi \to \gamma (K^{+}{K}^{-}{\pi }^{+}{\pi }^{-})$
• A Measurement of the Mass and Full-Width of the ${\eta }_c$ Meson

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• First Measurements of eta_c Decaying into K^+K^-2(pi^+pi^-) and 3(pi^+pi^-)