Please teach me this:(adsbygoogle = window.adsbygoogle || []).push({});

Why the Lagrangian in QFT must involve derivative of field? Is it correct that because fermions and bosons(meaning all things) obey Dirac and Klein-Gordon equations,then the corresponding Lagrangians include the derivative of field?

(I know that the derivative has a important role in Gauge Local Symmetries(leading to comparator that reserve the Gauge Symmetry of the derivative))

Thank you very much for your kind helping.

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

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

# Why the Lagrangian must involve derivative of field?

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