Could somebody please remind me why the e-values of the Casimir operator p.p (4-vector product) are the mass^2. This relation is clear to me when the field in question fulfils the Klein-Gordon equation but what about the general case?(adsbygoogle = window.adsbygoogle || []).push({});

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

Join Physics Forums Today!

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

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

# Casimir operator

Loading...

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