Measurements of the generalized electric and magnetic polarizabilities of the proton at low Q2 using the virtual Compton scattering reaction

Experimental details of a virtual Compton scattering (VCS) experiment performed on the proton at the MIT-Bates out-of-plane scattering facility are presented. The VCS response functions P-LL - P-TT/epsilon and P-LT have been measured at Q(2) = 0.057 GeV2/c(2). The generalized electric and magnetic polarizabilities, alpha(Q(2)) and beta(Q(2)), and the mean-square electric polarizability radius < r(alpha)(2)> are obtained from a dispersion analysis of the data. The results are in good agreement with O(p(3)) heavy baryon chiral perturbation and indicate the dominance of mesonic effects in the polarizabilities.