Observation of an alternative $\ddot{I}{‡}_{c0}(2P)$ candidate in $e^{+}{e}^{-}\to J/\ddot{I}ˆD\bar{D}$

Abstract

We perform a full amplitude analysis of the process $e^{+}{e}^{-}\to J/\ddot{I}ˆD\bar{D}$, where $D$ refers to either $D^0$ or $D^{+}$. A new charmoniumlike state $X^{\ast }(3860)$ that decays to $D\bar{D}$ is observed with a significance of $6.5\ddot{I}ƒ$. Its mass is ($3862_{-32}^{+26}{}_{-13}^{+40}$) MeV/$c^2$ and width is ($201_{-67}^{+154}{}_{-82}^{+88}$) MeV. The $J^{PC}=0^{++}$ hypothesis is favored over the $2^{++}$ hypothesis at the level of $2.5\ddot{I}ƒ$. The analysis is based on the 980 ${\mathrm{fb}}^{-1}$ data sample collected by the Belle detector at the asymmetric-energy $e^{+}{e}^{-}$ collider KEKB.

17 pages, 11 figures