Production and decays of the light pseudoscalar boson $\eta$ at the LHC in the simplest little Higgs model

TL;DR

This paper investigates the production and decay signatures of a light pseudoscalar boson $ ext{ exteta}$ in the simplest little Higgs model at the LHC, highlighting promising channels for detection and their phenomenological implications.

Contribution

It provides detailed calculations of $ ext{ exteta}$ production and decay modes at the LHC within the simplest little Higgs model, emphasizing the $ au^+ au^-$ decay channel and associated production with top quarks.

Findings

$tar t ext{ exteta}$ production yields sizable events.

The $ ext{ exteta}$ decay to $ au^+ au^-$ is significant below the $bar b$ threshold.

Associated production channels can effectively suppress backgrounds.

Abstract

In many extensions of the standard model, the Higgs sector often contains an additional pseudoscalar boson. A good example is the SU(3) simplest little Higgs model, which accommodates a light pseudoscalar boson $\eta$ with quite different characteristics from those in other multi-Higgs-doublet models. We study various phenomenological signatures of the $\eta$ at the LHC. In particular, we calculate in details both production and decays in the Drell-Yan type channel $q \bar{q} \to Z/Z' \to h \eta$, and in the associated production with a $t\bar t$ pair, $gg (q\bar q) \to t \bar t \eta$. We emphasize the $\tau^+ \tau^-$ decay mode of the $\eta$ boson when its mass is below the $b\bar b$ threshold. We show that $t\bar t \eta$ production is in fact large enough to give a sizable number of events while suppressing the backgrounds. We also comment on the direct gluon fusion process and the indirect decay from the heavy $T$ quark ($T \to t \eta$)