When calulating near resonant cross sections one usually inserts a mass width in the denominator of the propagator. This should, at least as I have understood it, correspond to taking the higher order diagrams into account.(adsbygoogle = window.adsbygoogle || []).push({});

What I would like to see is a proof for the equivalence between inserting a mass width and calculating the process to higer orders. Anyone's got a reference to this?

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Mass width in the propagator?

**Physics Forums | Science Articles, Homework Help, Discussion**