Study of e+e-→pp̄ via initial-state radiation at BABAR

Abstract

The process e+e-→pp̄γ is studied using 469 fb-1 of integrated luminosity collected with the BABAR detector at the SLAC National Accelerator Laboratory, at an e+e - center-of-mass energy of 10.6 GeV. From the analysis of the pp̄ invariant mass spectrum, the energy dependence of the cross section for e+e-→pp̄ is measured from threshold to 4.5 GeV. The energy dependence of the ratio of electric and magnetic form factors, |GE/GM|, and the asymmetry in the proton angular distribution are measured for pp̄ masses below 3 GeV. The branching fractions for the decays J/ψ→pp̄ and ψ(2S)→pp̄ are also determined. © 2013 American Physical Society.