Measurements of $\mathrm{\Sigma }$ electromagnetic form factors in the time-like region using the untagged initial-state radiation technique

The process $e^{+}{e}^{-}\to {\mathrm{\Sigma }}^{+}{\bar{\mathrm{\Sigma }}}^{-}$ is studied from threshold up to 3.04 GeV/$c^2$ via the initial-state radiation technique using data with an integrated luminosity of 12.0 fb${}^{-1}$, collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of $\mathrm{\Sigma }$ are measured in eleven ${\mathrm{\Sigma }}^{+}{\bar{\mathrm{\Sigma }}}^{-}$ invariant mass intervals from threshold to 3.04 GeV/$c^2$. The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays $J\mathrm{/}\psi \to {\mathrm{\Sigma }}^{+}{\bar{\mathrm{\Sigma }}}^{-}$ and $\psi (3686)\to {\mathrm{\Sigma }}^{+}{\bar{\mathrm{\Sigma }}}^{-}$ are determined and the obtained results are consistent with the previous results of BESIII.