A Symmetry in terms of Lagrangian

[zaman786]

TL;DR

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]

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

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.

 

[zaman786]

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.

ok- got it - thanks