Non-perturbative evaluation of some QED contributions to the muonic   hydrogen $\bm{n=2}$ Lamb shift and hyperfine structure
  The largest contributions to the $n=2$ Lamb-shift, fine structure interval and $2s$ hyperfine structure of muonic hydrogen are calculated by exact numerical evaluations of the Dirac equation, rather than by a perturbation expansion in powers of $1/c$, in the framework of non-relativistic quantum electrodynamics. Previous calculations and the validity of the perturbation expansion for light elements are confirmed. The dependence of the various effects on the nuclear size and model are studied 
Paul Indelicato (LKB - Jussieu)
physics.atom-ph