well hi poeple i just find out about this site i need a help i think i still didn't get a pint about gauge theory in strong etc interactions so i can imagine it for em interactions and U(1) symm but what happens with SU(2) and SU(3)? also what that is exactly means when you say gauge invariance (largangian of interaction is invariant under some transformations called gauge transf, but what is the exact roll of e.g. SU(3)?)
