Baryon electromagnetic form factors at BESIII

Helmholtz-Institut Mainz, Germany

^* e-mail: adbeyssi@uni-mainz.de

Published online: 27 March 2017

Abstract

Electromagnetic form factors are fundamental quantities which parameterize the electric and magnetic structure of hadrons. This contribution reports on the measurements of baryon electromagnetic form factors at the BESIII experiment in Beijing. The Beijing e⁺e⁻ collider BEPCII is a double-ring symmetric collider running at √s between 2.0 and 4.6 GeV. Baryon electromagnetic form factors can be measured at BESIII in direct e⁺e⁻-annihilation and in initial state radiation processes. Based on the data collected by the BESIII detector at 12 center of mass energies between 2.23 and 3.67 GeV, the e⁺e⁻ → p̄p cross section and the time-like proton form factor is measured. Preliminary results from the analysis of the initial state radiation process e⁺e⁻ → p̄pγ using a data set of 7.408 fb⁻¹ collected at center-of-mass energies between 3.773 and 4.6 GeV, are also presented. The cross section for $$e^{+}{e}^{-}\to \overline{\Lambda }\Lambda$$ is measured based on 40.5 pb⁻¹ data collected at 4 energy points from the threshold up to 3.08 GeV. Preliminary results on the total cross section and the Λ effective form factor are shown. Ongoing analysis based on the high luminosity energy scan from 2015 and from radiative return at different √s are also described.