Measurement of the e+e- --> p anti-p cross section in the energy range from 3.0 to 6.5 GeV

Understand

The e+ e- --> p anti-p cross section and the proton magnetic form factor have been measured in the center-of-mass energy range from 3.0 to 6.5 GeV using the initial-state-radiation technique with an undetected photon.

• This is the first measurement of the form factor at energies higher than 4.5 GeV.
• The analysis is based on 469 fb-1 of integrated luminosity collected with the BABAR detector at the PEP-II collider at e+e- center-of-mass energies near 10.6 GeV.
• The branching fractions for the decays J/psi --> p anti-p and psi(2S) --> p anti-p have also been measured.