Measurements of Σ+ and Σ− time-like electromagnetic form factors for center-of-mass energies from 2.3864 to 3.0200 GeV

The Born cross sections of the e + e − → Σ + Σ ¯ − and e + e − → Σ − Σ ¯ + processes are determined for center-of-mass energy from 2.3864 to 3.0200 GeV with the BESIII detector. The cross section lineshapes can be described properly by a pQCD function and the resulting ratio of effective form factors for the Σ + and Σ − is consistent with 3. In addition, ratios of the Σ + electric and magnetic form factors, | G E / G M | , are obtained at three center-of-mass energies through an analysis of the angular distributions. These measurements, which are studied for the first time in the off-resonance region, provide precision experimental input for understanding baryonic structure. The observed new features of the Σ ± form factors require more theoretical discussions for the hyperons.