Heavy charged scalars from $c\bar{s}$ fusion: A generic search strategy applied to a 3HDM with $\mathrm{U}(1) \times \mathrm{U}(1)$ family symmetry

TL;DR

This paper proposes a search strategy for heavy charged scalars produced via charm-strange fusion, applicable to a class of three Higgs doublet models with specific family symmetries, and demonstrates its effectiveness at the LHC.

Contribution

It introduces a model-independent search method for charged Higgs bosons decaying to W and the 125 GeV Higgs, applicable to 3HDMs with $ ext{U}(1) imes ext{U}(1)$ symmetry.

Findings

Multivariate analysis achieves high discrimination against SM background.

The proposed search strategy is effective for models with similar charged Higgs production channels.

The analysis can be adapted to other models with the same discovery channel.

Abstract

We describe a class of three Higgs doublet models (3HDMs) with a softly broken $\mathrm{U}(1) \times \mathrm{U}(1)$ family symmetry that enforces a Cabibbo-like quark mixing while forbidding tree-level flavour changing neutral currents. The hierarchy in the observed quark masses is partly explained by a softer hierarchy in the vacuum expectation values of the three Higgs doublets. As a consequence, the physical scalar spectrum contains a Standard Model (SM) like Higgs boson $h_{125}$ while exotic scalars couple the strongest to the second quark family, leading to rather unconventional discovery channels that could be probed at the Large Hadron Collider. In particular, we describe a search strategy for the lightest charged Higgs boson $H^{\pm}$, through the process $c\bar s\to H^{+}\to W^+\,h_{125}$, using a multivariate analysis that leads to an excellent discriminatory power against the SM background. Although the analysis is applied to the proposed class of 3HDMs, we employ a model-independent formulation such that it can be applied to any other model with the same discovery channel.