The cross section for the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$ is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using $9\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of $(4222.0\ifmmode\pm\else\textpm\fi{}3.1\ifmmode\pm\else\textpm\fi{}1.4)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and a width of $(44.1\ifmmode\pm\else\textpm\fi{}4.3\ifmmode\pm\else\textpm\fi{}2.0)\text{ }\text{ }\mathrm{MeV}$, while the second one has a mass of $(4320.0\ifmmode\pm\else\textpm\fi{}10.4\ifmmode\pm\else\textpm\fi{}7.0)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and a width of $(101.{4}_{\ensuremath{-}19.7}^{+25.3}\ifmmode\pm\else\textpm\fi{}10.2)\text{ }\text{ }\mathrm{MeV}$, where the first errors are statistical and second ones are systematic. The first resonance agrees with the $Y(4260)$ resonance reported by previous experiments. The precision of its resonant parameters is improved significantly. The second resonance is observed in ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$ for the first time. The statistical significance of this resonance is estimated to be larger than $7.6\ensuremath{\sigma}$. The mass and width of the second resonance agree with the $Y(4360)$ resonance reported by the BABAR and Belle experiments within errors. Finally, the $Y(4008)$ resonance previously observed by the Belle experiment is not confirmed in the description of the BESIII data.
Precise Measurement of the e+e−→π+π−J/ψ Cross Section at Center-of-Mass Energies from 3.77 to 4.60 GeV | Litlas
