Abstract
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, |GE/GM|, 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.
Highlights
Nucleons, as the lightest baryons, are the largest component of the observable matter in the universe, and were shown to be non-pointlike particles in the middle of last century [1,2]
Despite the fact that much work has been done on the EM structures of protons in both the space-like and time-like regions [9,10,11,12,13,14], experimental information regarding the Electromagnetic form factors (EMFFs) of hyperons remains limited [15,16,17,18]
− c is observed by the BESIII experiment [29], where the cross section of plateau near threshold is around 240 pb
Summary
As the lightest baryons, are the largest component of the observable matter in the universe, and were shown to be non-pointlike particles in the middle of last century [1,2]. For charged point-like fermion pairs, the cross section at threshold is non-zero, σ (4m2B ) = π 2α3/2m2B = 848(mp /mB ) pb, where mp is the proton mass [28], and grows with increasing β. The cross section of plateau near threshold is consistent with the 848 pb expectation for a point-like charged particle. In this case, the p pis produced by a virtual photon with Q 2 =. − c is observed by the BESIII experiment [29], where the cross section of plateau near threshold is around 240 pb This is 1.6 times the predicted value for point-like charged particles. To understand the nature of these threshold effects, experimental measurements of the near threshold charged pair production of other hyperons will be of critical importance
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call