Closing the Wedge: Search Strategies for Extended Higgs Sectors with Heavy Flavor Final States

TL;DR

This paper explores search strategies for extended Higgs sectors at the high-luminosity LHC, focusing on multi-top final states within a Two Higgs Doublet Model, and assesses their effectiveness in constraining heavy Higgs bosons.

Contribution

It introduces optimized search channels for heavy Higgs bosons in extended sectors using multi-top final states and evaluates their sensitivity at the high-luminosity LHC.

Findings

Single and 3 lepton final states can constrain heavy Higgs masses up to ~750 GeV at low tanβ.

Systematic uncertainties significantly affect the power of the 3 lepton final state.

Constraints are limited for Higgs bosons with couplings to tops smaller than the top Yukawa.

Abstract

We consider search strategies for an extended Higgs sector at the high-luminosity LHC14 utilizing multi-top final states. In the framework of a Two Higgs Doublet Model, the purely top final states ($t\bar t, \, 4t$) are important channels for heavy Higgs bosons with masses in the wedge above $2\,m_t$ and at low values of $\tan\beta$, while a $2 b 2t$ final state is most relevant at moderate values of $\tan \beta$. We find, in the $t\bar t H$ channel, with $H \rightarrow t \bar t$, that both single and 3 lepton final states can provide statistically significant constraints at low values of $\tan \beta$ for $m_A$ as high as $\sim 750$ GeV. When systematics on the $t \bar t$ background are taken into account, however, the 3 lepton final state is more powerful, though the precise constraint depends fairly sensitively on lepton fake rates. We also find that neither $2b2t$ nor $t \bar t$ final states provide constraints on additional heavy Higgs bosons with couplings to tops smaller than the top Yukawa due to expected systematic uncertainties in the $t \bar t$ background.