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

作者：Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; An, Q.; Anita; Bai, Y.; Bakina, O.; Ferroli, R. Baldini; Balossino, I; Ban, Y.; Begzsuren, K.; Bennett, J., V; Berger, N.; Bertani, M.; Bettoni, D.; Bianchi, F.; Biernat, J.; Bloms, J.; Bortone, A.; Boyko, I; Briere, R. A.; Cai, H.; Cai, X.; Calcaterra, A.; Cao, G. F.; Cao, N.; Cetin, S. A.; Chang, J. F.; Chang, W. L.; Chelkov, G.; Chen, D. Y.; Chen, G.; Chen, H. S.; Chen, M. L.; Chen, S. J.; Chen, X. R.

来源：Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics , 2021, 814: 136110.

DOI：10.1016/j.physletb.2021.136110

• BESIII
• Sigma hyperon
• Cross section
• Electromagnetic form factor

The Born cross sections of the e(+)e(-) -> Sigma(+)(Sigma) over bar (-) and e(+)e(-)-> Sigma(-)(Sigma) over bar (+) processes are determined for centerof-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 Sigma(+) and Sigma(-) is consistent with 3. In addition, ratios of the Sigma(+) electric and magnetic form factors, vertical bar G(E)/G(M)vertical bar. 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 Sigma(+/-) form factors require more theoretical discussions for the hyperons.