Search for pseudoscalar Higgs boson $A_0$ of the Bestest Little Higgs model at the LHC and FCC-hh

Abstract: We analyse the sensitivity of the Large Hadron Collider (LHC) and the Future Circular Collider-hadron-hadron (FCC-hh) to the existence of pseudoscalar Higgs boson $A_0$ predicted by the Bestest Little Higgs model. We study the tree-level (two and three body) and one-loop decays of the pseudoscalar, $$A_0 \to b\bar b, t \bar t, \gamma t\bar t, \gamma b \bar b, Zt\bar t, Zb \bar b, Wt\bar b, h_0 t \bar t, h_0 b \bar b$$, and $A_0 \to \gamma\gamma, \gamma Z, ZZ, gg, WW$, respectively. In addition, we perform a phenomenological study of the production of the pseudoscalar $A_0$ via gluon fusion $gg \to A_0 \to Y$ processes, where $Y \equiv \gamma\gamma, \gamma Z, ZZ, gg, WW$. From the cross section of the processes of interest and the expected integrated luminosity of the LHC and FCC-hh, we determined the number of events that could be produced in both colliders.