Top quark polarization as a probe of charged Higgs bosons

TL;DR

This paper investigates how the polarization of top quarks produced in charged Higgs boson decays at the LHC can reveal the underlying Higgs mechanism and distinguish between different 2HDM models based on their Yukawa couplings.

Contribution

It demonstrates that top quark polarization and decay observables can differentiate between Type-I and Type-Y 2HDM realizations of charged Higgs bosons at the LHC.

Findings

Top quark polarization depends on the Higgs Yukawa coupling structure.

Inclusive and exclusive observables can identify charged Higgs signals.

Distinct polarization patterns differentiate 2HDM types.

Abstract

We study the production and decay of a heavy charged Higgs boson in the $bg\to tH^-$ and $H^-\to b\bar t$ processes at the Large Hadron Collider (LHC). We show that the chiral structure of the $H^-t\bar b$ vertex entering both stages is sensitive to the underlying Higgs mechanism of Electro-Weak Symmetry Breaking (EWSB) and we specifically demonstrate that one could distinguish between two popular realizations of a 2-Higgs Double Model (2HDM) embedding a new $H^\pm$ state, i.e., those with Type-I and -Y Yukawa couplings. The chiral structure of such a vertex, which is different in the two cases, in turn triggers a particular spin state of the top quark which is then transmitted to its decay products. Hence, both inclusive rates and exclusive observables can be used to extract the presence of such a charged Higgs boson state in LHC data.