Proton Compton effect: A measurement of the electric and magnetic polarizabilities of the proton

Abstract

We have measured the Compton-scattering cross section on hydrogen at 60° and 135° using monochromatic tagged photons spanning the energy between 32 and 72 MeV. These data, when analyzed with a low-energy expansion of the scattering cross-section formula, provides a determination of values for the electric and magnetic polarizabilities of the proton. We find, respectively, α¯=(10.9±2.2±1.3)×${10}^{\mathrm{-}4}$ ${\mathrm{fm}}^3$ and β¯=(3.3∓2.2∓1.3)×${10}^{\mathrm{-}4}$ ${\mathrm{fm}}^3$, assuming the model-independent constraint α¯+β¯=14.2×${10}^{\mathrm{-}4}$ ${\mathrm{fm}}^3$.