Decays Z --> ggg and Z-prime --> ggg in the minimal 331 model

TL;DR

This paper calculates the one-loop couplings of Z and Z' bosons to three gluons in the minimal 331 model, revealing that Z' decay is significantly affected by exotic quarks while Z decay is not.

Contribution

It provides a complete one-loop calculation of Zggg and Z'ggg couplings in the minimal 331 model, including a compact SU_C(3)-invariant vertex function.

Findings

Z decay is insensitive to exotic quarks.

Z' decay is sensitive to both standard and exotic quarks.

Z' to ggg branching ratio exceeds Z to ggg by about four times.

Abstract

We perform a complete calculation at the one-loop level for the Zggg and Z'ggg couplings in the context of the minimal 331 model, which predicts the existence of a new Z' gauge boson and new exotic quarks. Bose symmetry is exploited to write a compact and manifest SU_C(3)-invariant vertex function for the Vggg (V=Z,Z') coupling. Previous results on the $Z\to ggg$ decay in the standard model are reproduced. It is found that this decay is insensitive to the effects of the new exotic quarks. This in contrast with the $Z'\to ggg$ decay, which is sensitive to both the standard model and exotic quarks, whose branching ratio is larger than that of the $Z\to ggg$ transition by about a factor of 4.