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

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 $η$ with quite different characteristics from those in other multi-Higgs-doublet models. We study various phenomenological signatures of the $η$ at the LHC. In particular, we calculate in details both production and decays in the Drell-Yan type channel $q \bar{q} \to Z/Z' \to h η$, and in the associated production with a $t\bar t$ pair, $gg (q\bar q) \to t \bar t η$. We emphasize the $τ^+ τ^-$ decay mode of the $η$ boson when its mass is below the $b\bar b$ threshold. We show that $t\bar t η$ 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 ($T \to t η$)