Electron-Positron Elastic Scattering at a Center-of-Mass Energy of 4 GeV

Abstract

We have measured the cross section for electron-positron elastic scattering at 4 GeV center-of-mass energy for scattering angles between 50° and 130°. We have calculated the theoretical (quantum-electrodynamics) cross section including a radiative correction calculated using the peaking approximation. The ratio of the experimental and theoretical cross sections is 0.88 ± 0.10. We therefore obtain new bounds on the quantum-electrodynamics breakdown parameters, ${\Lambda }_{+}>12\mathrm{}$ GeV and ${\Lambda }_{-}>6\mathrm{}$ GeV.