Z'-> ggg decay in left-right symmetric models with three and four fermion families

TL;DR

This paper analyzes the decay of a Z' boson into three gluons within left-right symmetric models, exploring effects of a fourth fermion family and providing estimated branching ratios for various Z' masses.

Contribution

It presents the calculation of the Z'-> ggg decay branching ratio in left-right symmetric models, including the impact of a fourth fermion family and threshold effects.

Findings

Branching ratio BR(Z'-> ggg) is (1.2-2.8) x 10^{-5} for Z' masses 700-1500 GeV.

Enhanced branching ratios near the b' b' threshold due to the fourth family.

BR(Z'-> ggg) can reach (1-6) x 10^{-5} considering fourth-generation quark masses.

Abstract

We study the Z'-> ggg decay in the context of a left-right symmetric gauge theory. We obtain a branching ratio BR(Z'-> ggg)=\Gamma(Z'->ggg)/ \Gamma(Z'-> q\bar{q})= (1.2-2.8) x 10^{-5} for m_{Z'}=(700-1500) GeV. We also study the contribution of a fourth fermion family. We find an enhancement in the branching ratio for Z' masses close to the \bar{b'}b' threshold and a dip for Z' masses close to the \bar{t'}t' threshold. Using the values of the fourth generation quark masses allowed by electroweak precision data we obtain a branching ratio BR(Z'-> ggg)= (1-6)x 10^{-5} for m_{Z'}=(700-1500) GeV.