Ta. Heim et al., Coherent and incoherent atomic scattering: formalism and application to pionium interacting with matter, J PHYS B, 33(18), 2000, pp. 3583-3604
Citations number
25
Categorie Soggetti
Physics
Journal title
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
The experimental determination of the lifetime of pionium provides a very i
mportant test of chiral perturbation theory. This quantity is determined in
the DIRAC experiment at CERN. In the analysis of this experiment, the brea
kup probabilities of pionium in matter are needed to high accuracy as a the
oretical input. We study in detail the influence of the target electrons. T
hey contribute through screening and incoherent effects. We use Dirac-Hartr
ee-Fock-Slater wavefunctions in order to determine the corresponding form f
actors. We find that the inner-shell electrons contribute less than the wea
kly bound outer electrons. Furthermore, we establish a more rigorous estima
te for the magnitude of the contribution from the transverse current (magne
tic terms thus far neglected in the calculations).