Top Quark Properties in Little Higgs Models

TL;DR

This work addresses how Little Higgs theories modify top-quark gauge couplings. It computes shifts in the $t\bar{t}Z$ and $t\bar{b}W$ vertices arising from mixing with a TeV-scale heavy top $T$ and from gauge-boson mixing, considering both the Littlest Higgs (LH) and the LH with T parity (LHT). The analysis, based on the LH $SU(5)/SO(5)$ framework with a reduced gauge group, shows that these corrections can reach several percent and remain within the ILC’s sensitivity across natural parameter ranges, while the LHC has more limited reach for these observables. The results provide a direct probe of the top sector in Little Higgs theories and help test the naturalness-driven parameter space.

Abstract

We study the shifts in the gauge couplings of the top quark induced in the Littlest Higgs model with and without T parity. We find that the ILC will be able to observe the shifts throughout the natural range of model parameters.