Leptonic $Z$ decays in the littlest $Higgs$ model with T-parity

TL;DR

This paper investigates how T-odd leptons predicted by the littlest Higgs model with T-parity affect leptonic Z decays, providing potential constraints on the model's parameters based on experimental data.

Contribution

It calculates the one-loop contributions of T-odd leptons to leptonic Z decays within the LHT model, highlighting their potential significance and experimental constraints.

Findings

T-odd leptons significantly affect leptonic Z decay branching ratios

Experimental data can constrain LHT model parameters

Most parameter space shows notable contributions from T-odd leptons

Abstract

The littlest $Higgs$ model with T-parity (called the $LHT$ model) predicts the existence of the T-odd leptons, which can generate contributions to some leptonic processes at the one-loop level. We calculate their contributions to the leptonic $Z$ decay processes $Z\to l\bar{l'}$, $Z\to l\bar{l}$, and $Z\rightarro \nu\bar{\nu}$. We find that the T-odd leptons can give significant contributions to the branching ratios of these decay processes in most of the parameter space. The experimental measurement values might generate constraints on the free parameters of the $LHT$ model.