The Z, Z' → γγγ decays in the minimal 331 model

A complete calculation at one-loop level for the Z, Z' → γγγ decays is presented in the context of the minimal 331 model, which predicts the existence of a new Z' neutral gauge boson, Y++, Y+ charged gauge bosons, new exotic quarks and charged scalars. Bose symmetry is exploited to write a compact and manifest SUC[(3)-invariant vertex function for the γγγV0 coupling. Previous results on the Z → γγγ are reproduced (Br(Z → γγγ) ~ 10−10). It is found that this decay is insensitive to the effects of new heavy particles. This contrasts with the Z' → γγγ decay where the associated branching ratio is of the order of 10−6.