Coherent and incoherent atomic scattering: formalism and application to pionium interacting with matter

T A Heim, K Hencken, D Trautmann, G Baur
2000 Journal of Physics B: Atomic, Molecular and Optical Physics  
The experimental determination of the lifetime of pionium provides a very important test on chiral perturbation theory. This quantity is determined in the DIRAC experiment at CERN. In the analysis of this experiment, the breakup probabilities of of pionium in matter are needed to high accuracy as a theoretical input. We study in detail the influence of the target electrons. They contribute through screening and incoherent effects. We use Dirac-Hartree- Fock-Slater wavefunctions in order to
more » ... mine the corresponding form factors. We find that the inner-shell electrons contribute less than the weakly bound outer electrons. Furthermore, we establish a more rigorous estimate for the magnitude of the contributions form the transverse current (magnetic terms thus far neglected in the calculations).
doi:10.1088/0953-4075/33/18/308 fatcat:a5i4qp5buvbn3l4cvbuamjw6o4