 Kinoshita–Lee–Nauenberg theorem

The Kinoshita–Lee–Nauenberg theorem is a result in the field of quantum field theory and particle physics that addresses the issue of how certain types of divergences in amplitudes of scattering processes should be handled when considering the effects of external legs in perturbative calculations. The theorem is particularly relevant in high-energy physics, where particle processes can be complicated due to the presence of many interacting fields.