Polarizability of the nucleon

Abstract

The status of the experimental and theoretical investigations of the nucleon is presented. This includes a confirmation of the validity of the previously  introduced recommended  polarizabilities. It is shown that the only meaningful approach to a prediction of the polarizabilities  is obtained from nonsubtracted dispersion theory, where the appropriate degrees of freedon taken from other precise experimental data are taken into account. The present  values of the recommended polarizabilities are \(\alpha_p=12.0\pm 0.5\), \(\beta_p=1.9\mp 0.5\), \(\alpha_n=12.6\pm 1.2\),  \(\beta_n=2.6\mp 1.2\) in units of \(10^{-4}\)fm\(^3\) and \(\gamma^{(p)}_\pi =-36.4 \pm 1.5\),  \(\gamma^{(n)}_\pi=+58.6\pm 4.0\), \(\gamma^{(p)}_0= -0.58\pm 0.20\), \(\gamma^{(n)}_0=+0.38\pm 0.22\) in units of \(10^{-4}\)fm\(^4\).