Self-coupling of the gauge bosons

Up to this point we have considered only that part of C that contains the Higgs scalars and their coupling to the gauge bosons. 

For the gauge bosons themselves we have the expected gauge invariant terms (see (2.3.19) and (2.3.37)) 

The photon was chosen so that the theory remained invariant under transformations generated by (7 + T3) which for ,0 would be the usual electromagnetic gauge transformations. To check what happens to the photon under this transformation we must set 0 x) = 0 (x) = 0 and 6 x) = 6 x) in (4.2.3). 

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