Hadronic Vacuum Polarization and the Lamb Shift
  Recent improvements in the determination of the running of the fine-structure constant also allow an update of the hadronic vacuum-polarization contribution to the Lamb shift. We find a shift of -3.40(7) kHz to the 1S level of hydrogen. We also comment on the contribution of this effect to the determination by elastic electron scattering of the r.m.s. radii of nuclei. 
J.L. Friar, J. Martorell, and D.W.L. Sprung