Source: wikibot/kallen-function
= Källén function
{wiki=Källén_function}
The Källén function, named after the Swedish physicist Gunnar Källén, is a function used in quantum field theory and particle physics that describes the relationship between the invariant mass squared \\( s \\) of a system of particles and the squared momenta of the particles involved. It is particularly useful in the context of scattering processes and interaction between particles.