Test of Quantum Electrodynamics by Electron-Electron Scattering

We have measured the differential cross section for electron-electron scattering at a total energy of 1112 MeV in the center-of-mass system. Using the Feynman regulator as a model for violation, with $K$ a cutoff momentum, we find ${K}^{\ensuremath{-}2}=0.044\ifmmode\pm\else\textpm\fi{}0.049 {(\frac{\mathrm{GeV}}{c})}^{\ensuremath{-}2}$. The error quoted represents a statistical contribution of \ifmmode\pm\else\textpm\fi{}0.042 combined in quadrature with \ifmmode\pm\else\textpm\fi{}0.025 representing the uncertainty of possible systematic contributions. This result is one of the most sensitive high-momentum-transfer tests of the photon propagator in quantum electrodynamics.