Phenomenology of 2HDM with vectorlike quarks

In this paper, we examine the consistency of the Large Hadron Collider (LHC) data collected during Runs 1 and 2 by the ATLAS and CMS experiments with the predictions of a 2-Higgs doublet model embedding vectorlike quarks (VLQs) for $pp\to H$, $A$ production and $H$, $A\to \gamma \gamma $ decay mechanisms, respectively, of (nearly) degenerate $CP$-even ($H$) and $CP$-odd ($A$) Higgs bosons. We show that a scenario containing one single VLQ with electromagnetic charge $2/3$ can explain the above ATLAS and CMS data for masses in the region $350\text{}\text{}\mathrm{GeV}\le {m}_{\mathrm{VLQ}}\le 1.5\text{}\text{}\mathrm{TeV}$ or so, depending on $\mathrm{tan}\beta $, and for several values of the mixing angle between the top quark ($t$) and its VLQ counterpart ($T$). We then perform a global fit onto the model by including all relevant experimental as well as theoretical constraints. The surviving samples of our analysis are discussed within $2\sigma $ of the LHC measurements. Additionally, we also comment on the recent anomalous result reported by CMS using Run 2 data on the associated Standard Model Higgs boson production with top quark pairs $pp\to t\overline{t}h$ with an observed significance of $3.3\sigma $. Other than these specific examples, we also present a phenomenological analysis of the main features of the model, including the most promising $T$ decay channels.