Evidence for Two Excited $\hat{I}{\text{c◯}}^{-}$ Hyperons

Abstract

Using $e^{+}{e}^{-}$ collision data corresponding to an integrated luminosity of 19,fb${}^{-1}$ collected by the BESIII detector at center-of-mass energies ranging from 4.13 to 4.70,GeV, we report the first evidence for a new excited $\hat{I}{\text{c◯}}^{-}$ hyperon, the $\hat{I}\text{c◯}(2109{)}^{-}$, through the process $e^{+}{e}^{-}\to \hat{I}\text{c◯}(2109{)}^{-}\bar{\hat{I}}{\text{c◯}}^{+}+c.c.$ with a significance of 4.1 $\ddot{I}ƒ$. The mass and width of $\hat{I}\text{c◯}(2109{)}^{-}$ are measured to be $2108.5\pm 5.2_{\mathrm{stat}}\pm 0.9_{\mathrm{syst}}\mathrm{MeV}/c^2$ and $18.3\pm 16.4_{\mathrm{stat}}\pm 5.7_{\mathrm{syst}}\mathrm{MeV}$, respectively. We also present evidence for a new production mechanism for the previously identified $\hat{I}\text{c◯}(2012{)}^{-}$ via the process $e^{+}{e}^{-}\to \hat{I}\text{c◯}(2012{)}^{-}\bar{\hat{I}}{\text{c◯}}^{+}+c.c.$ with a significance of 3.5 $\ddot{I}ƒ$.

8 pages, 2 figures