Study of theP-Wave Charmonium StateχcJinψ(2S)Decays

The processes $\psi \left(2S\right)\to \gamma {\pi }^{+}{\pi }^{-}$, $\gamma K^{+}{K}^{-}$, and $\gamma p\overline{p}$ have been studied using a sample of $3.79\times {10}^6\psi \left(2S\right)$ decays. We determine the total width of the ${\chi }_{c0\mathrm{}}$ to be ${\Gamma }_{{\chi }_{c0\mathrm{}}}^{\mathrm{tot}}=14.3\mathrm{}\pm 2.0\pm 3.0\mathrm{MeV}$. We present the first measurement of the branching fraction $B({\chi }_{c0\mathrm{}}\to p\overline{p})=(15.9\pm 4.3\pm 5.3)\times {10}^{-5\mathrm{}}$, where the first error is statistical and the second one is systematic. Branching fractions of ${\chi }_{c0,2\mathrm{}}\to {\pi }^{+}{\pi }^{-}$ and $K^{+}{K}^{-}$ are also reported.