Angular distribution and correlation of photons emitted during dielectronic recombination into hydrogen-like ions

In the process of dielectronic recombination into a hydrogen-like ion, the system is not stable until both electrons are de-excited, giving rise to the emission of two photons. A fully relativistic approach employing perturbative methods is carried out and leads to expressions for the total and triple-differential cross sections. This allows the study of correlation effects between both photons