Measurement of the cross section for $e^{+}e^{-}rightarrowXi^{-}barXi^{+}$ and observation of an excited $Xi$ baryon

Using a total of 11.0 fb$^{-1}$ of $e^{+}e^{-}$ collision data with center-of-mass energies between 4.009 GeV and 4.6 GeV and collected with the BESIII detector at BEPCII, we measure fifteen exclusive cross sections and effective form factors for the process $e^{+}e^{-}rightarrowXi^{-}barXi^{+}$ by means of a single baryon-tag method. After performing a fit to the dressed cross section of $e^{+}e^{-}rightarrowXi^{-}barXi^{+}$, no significant $psi(4230)$ or $psi(4260)$ resonance is observed in the $Xi^{-}barXi^{+}$ final states, and upper limits at the 90% confidence level on $Gamma_{ee}mathcal{B}$ for the processes $psi(4230)$/$psi(4260)rightarrowXi^{-}barXi^{+}$ are determined. In addition, an excited $Xi$ baryon at 1820 MeV/$c^{2}$ is observed with a statistical significance of 6.2 $sim$ 6.5$sigma$ by including the systematic uncertainty, and the mass and width are measured to be $M = (1825.5 pm 4.7 pm 4.7)$~MeV/$c^{2}$ and $Gamma = (17.0 pm 15.0 pm 7.9)$~MeV, which confirms the existence of the $J^{P}=frac{3}{2}^{-}$ state $Xi(1820)$.