Trilepton Signatures of Light Charged and CP-odd Higgs Bosons in Top Quark Decays

TL;DR

This paper explores how light CP-odd Higgs bosons in certain models can alter top quark decay signatures, proposing new search strategies at the LHC to detect these effects and constrain the model parameters.

Contribution

It introduces a novel scenario where charged Higgs decays predominantly into W and a light CP-odd Higgs, and suggests specific LHC search strategies to probe this parameter space.

Findings

The scenario remains unconstrained in large parameter regions due to decay mode dominance.

A proposed search in 8 TeV LHC data can effectively constrain most of the allowed parameter space.

Existing trilepton searches lack sensitivity due to isolation criteria.

Abstract

In singlet extensions of the two Higgs doublet model, a light CP-odd Higgs boson (A) can significantly modify decay modes of the charged Higgs, without necessarily affecting decay modes of the standard model-like Higgs boson. These effects can be sizable even if the doublet component of the light CP-odd Higgs is small, so that constraints from Upsilon decays and direct CP-odd Higgs production do not apply. We study a scenario in which the charged Higgs is produced in top quark decays, t -> H+ b, with dominant H+ -> W A. We focus on the CP-odd Higgs mass range below the bb threshold. We summarize all current experimental constraints and find that, as a result of H+ -> W A dominance, this scenario is not constrained in a large region of tan(beta), mH+, and CP-odd Higgs doublet component. We discuss search strategies based on A -> tau tau, with both taus decaying leptonically, and on the subleading decay mode A -> mu mu. We show that a search for t -> H+ b, H+ -> W A, A -> mu mu in 20 fb^-1 of 8 TeV LHC data can constrain most of the currently allowed parameter space. Existing trilepton searches are not sensitive to this signal due to the adopted isolation criteria.