ABSTRACT
The electron e2 receives a large momentum mevp, which is afterwards transferred onto e1. This is possible only if the static correlation of the two electrons in the helium target plays a non-negligible role. The relative importance of this so-called ‘indirect momentum matching’ mechanism has been estimated within the CDW-4B method. However, a proper introduction of the distortion of a free wave would automatically modify the long-range Coulomb perturbation through the emergence of an overall short-range potential which will then restore the usual concept of scattering.
