Radiative Corrections to Double Dalitz Decays: Effects on Invariant Mass   Distributions and Angular Correlations
  We review the theory of meson decays to two lepton pairs, including the cases of identical as well as non-identical leptons, as well as CP-conserving and CP-violating couplings. A complete lowest-order calculation of QED radiative corrections to these decays is discussed, and comparisons of predicted rates and kinematic distributions between tree-level and one-loop-corrected calculations are presented for both pi-zero and K-zero decays. 
A. R. Barker, H. Huang, P. A. Toale, and J. Engle