Probing the low mass pseudoscalar in flipped Two Higgs Doublet Model

TL;DR

This paper investigates the potential to detect a light pseudoscalar particle in the flipped Two Higgs Doublet Model at the LHC, proposing a specific search channel and demonstrating high detection prospects with advanced analysis techniques.

Contribution

It identifies a viable parameter space for a light pseudoscalar in flipped 2HDM and proposes an effective search strategy for its detection at the LHC.

Findings

Light pseudoscalar $A$ can exist in 20-60 GeV range within experimental constraints.

The $pp ightarrow A Z ightarrow bar{b} \, \ell^+ \ell^-$ channel is promising for detection.

High statistical significance achievable at high-luminosity LHC, especially for $m_A$ around 30-40 GeV.

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 $pp \rightarrow A Z(Z^{*}) \rightarrow b\bar{b} \ell^+ \ell^-$. 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.