Higher order proton structure corrections to the Lamb shift in muonic   hydrogen
  The recent conundrum with the proton charge radius inspires reconsideration of the corrections that enter into determinations of the proton size. We study the two-photon proton-structure corrections, with special consideration of the non-pole subtraction term in the dispersion relation, and using fits to modern data to evaluate the energy contributions. We find that individual contributions change more than the total, and present results with error estimates. 
Carl E. Carlson (Helmholtz Institut Mainz, and William and Mary) and   Marc Vanderhaeghen (U. Mainz)
hep-ph nucl-th physics.atom-ph