Symmetry in terms of Lagrangian

zaman786 said:

TL;DR Summary: how can we check symmetry of SM in terms of Lagrangian

Hi, as we know SM is symmetric under SU(3) X SU(2) X U(1) , But my question is , how can we check the invariance of terms in Lagrangian under these symmetries - thanks

Orodruin said:

You have to ensure that any of the terms entering the Lagrangian is in the trivial representation of the SM gauge groups. If they are, then the term is gauge invariant. If not it is not.