Nucleon Polarizability Contribution to the Hydrogen Lamb Shift and   Hydrogen -- Deuterium Isotope Shift
  The correction to the hydrogen Lamb shift due to the proton electric and magnetic polarizabilities is expressed analytically through their static values, which are known from experiment. The numerical value of the correction to the hydrogen 1S state is $ - 71 \pm 11 \pm 7$ Hz. Correction to the H-D 1S-2S -- isotope shift due to the proton and neutron polarizabilities is estimated as $ 53 \pm 9 \pm 11$ Hz. 
I.B. Khriplovich and R.A. Sen'kov