Probing the low mass pseudoscalar in flipped Two Higgs Doublet Model

Abstract

The phenomenology of the flipped two-Higgs-doublet model (2HDM) is relatively less explored so far, as compared to the other, commonly discussed, types. It is found that this scenario, like several others, admits of a light neutral pseudoscalar $A$ in the mass range 20 - 60 GeV, consistently with all current experimental data and theoretical constraints. However, the fact that such a pseudoscalar decays overwhelmingly into a $b\bar{b}$ pair makes its identification at the Large Hadron Collider (LHC) a challenging task. After identifying the region of the flipped 2HDM parameter space yielding a light pseudoscalar, we identify a useful search channel in the process $pp\to AZ(Z^{\ast })\to b\bar{b}{\ell }^{+}{\ell }^{-}$. A cut-based analysis, followed by one based on Boosted Decision Trees, shows that the light-$A$ scenario in flipped 2HDM should be detectable with rather high statistical significance at the high-luminosity LHC run, even after including systematic uncertainties. Furthermore, part of the parameter space, especially around $m_A=30-40$ GeV is amenable to detection at the discovery level within Run-2 itself.

Comments: 24 pages, 9 figures