Radiative decays Z_H-> V_i Z (V_i=\gamma, Z) in little Higgs models

TL;DR

This paper investigates the rare radiative decays of an extra neutral gauge boson, Z_H, into a photon or Z boson and a Z, within little Higgs models, analyzing their potential detectability at colliders.

Contribution

It provides the first detailed calculation of Z_H -> V_i Z decays at one-loop level in two little Higgs models, highlighting their dependence on anomaly cancellation mechanisms.

Findings

Z_H -> γ Z branching ratios can be comparable to tree-level decays.

Z_H -> Z Z decay is highly suppressed.

Future colliders like the linear collider improve detection prospects.

Abstract

The study of the phenomenology of an extra neutral gauge boson, Z_H, can can help us to unravel the underlying theory. We study the decay of such a particle into two neutral gauge bosons, Z_H -> V_i Z (V_i=\gamma, Z), in two popular versions of the little Higgs model: the littlest Higgs model (LHM) and the simplest little Higgs model (SLHM). These decays are induced at the one-loop level by a fermion triangle and are interesting as they are strongly dependent on the mechanism of anomaly cancellation of the model. All the relevant tree-level two- and three-body decays of the Z_H gauge boson are also calculated. It is found that the branching ratios for the Z_H-> \gamma Z decays can be as large as that of a tree-level three-body decay but the Z_H-> ZZ decay is very suppressed. We also discuss the experimental prospects for detecting these decays at the LHC and a future linear collider. We conclude that the latter would offer more chances for the detection of such rare decays.