Measurements of the Generalized Electric and Magnetic Polarizabilities of the Proton at Low Q~2 Using the Virtual-Compton-Scattering Reaction

摘要

The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q~2 = 0.057 GeV~2/c~2 are in agreement with O(p~3) heavy baryon chiral perturbation theory. The data support the dominance of mesonic effects in the polarizabilities.