Determination of the Proton's Electric and Magnetic Spectral Functions

Abstract

We employ the solution of the well-known airfoil equation to determine the spectral functions of the proton. The constraint that the electric and magnetic form factors are equal at threshold for proton-antiproton annihilation into an electron-positron pair is used throughout. A comparison of our results is made with the preliminary measurements of the cross section for this process and the Sachs constraint at infinite momentum transfer is also examined. We find spectral functions with a peak around 780 MeV, a zero around 1150 MeV, and a broad minimum around 1400 MeV.