Improving probes of $hAA$ coupling in the Type-X two Higgs Doublet Model scenario: the crucial role of $\ddot{I}„$-jet charge identification

Abstract

The exotic decay modes of the already discovered 125-GeV scalar into a pair of light pseudoscalars is a good probe of those new physics scenarios where such pseudoscalars exist. Searches in the mass region where the pseudoscalar ($A$) is lighter than 62.5 GeV have yielded null findings so far. No search has yet examined $m_A>62.5$ GeV where the cross section is suppressed by the off-shell pseudoscalar. We point out a possible enhancement of the sensitivity of probing $hAA$ coupling in the context of a Type-X two Higgs doublet model. We focus on $h\to A{A}^{(\ast )}\to 4\ddot{I}„$, and select events with two same-sign $\ddot{I}„$-jets along with a pair of same-sign leptons. This enables much more effective background elimination than in the erstwhile proposed channels. Taking two values of the $\ddot{I}„\ddot{I}„A$ coupling into account, we obtain limits on the $hAA$ coupling that can be probed at 2$\ddot{I}ƒ$ and 3$\ddot{I}ƒ$ significance, for $m_A$ ranging up to 85 GeV. For $m_A<62.5$ GeV, too, we find the probe through our suggested channel exhibits considerable improvement upon the usual $2\hat{I}¼2\ddot{I}„$-based searches conducted at the LHC. Within this region, achieving the reach of $\hat{I}{»}_{hAA}$ coupling at 3000 fb${}^{-1}$ luminosity using our strategy would require approximately $\sim$ 3.6$\times 10^5$ fb${}^{-1}$ luminosity using conventional $2\hat{I}¼2\ddot{I}„$-based searches.

23 pages, 2 figures