Heavy Higgs Coupled to Vector-like Quarks: Strong CP Problem and Search Prospects at the 14 TeV LHC

TL;DR

This paper proposes a model where a heavy Higgs boson interacts with vector-like quarks, potentially explaining the ATLAS diboson excess and predicting discoverability at the 14 TeV LHC up to 1 TeV mass.

Contribution

It introduces a novel heavy Higgs model linked to vector-like quarks and a Peccei-Quinn scalar, addressing the strong CP problem and LHC search prospects.

Findings

The model can explain the ATLAS diboson excess.

LHC at 14 TeV can discover heavy Higgs up to 1 TeV.

Boosted decision trees improve signal-background discrimination.

Abstract

Motivated by a solution to the strong CP problem we propose a model where a new heavy neutral CP-even Higgs boson couples to vector-like quarks enhancing its production cross section whose dominant decays are into weak bosons. The masses of the vector-like quarks are generated through interactions with a singlet scalar field charged under a broken global $U(1)$ symmetry providing a solution to the strong CP problem by means of the Peccei-Quinn mechanism. The diboson excess observed by the ATLAS Collaboration is discussed as the new heavy Higgs boson is a candidate to explain a possible signal in this channel. We also show that the 14 TeV LHC is capable of discovering this heavy Higgs with masses up to 1 TeV in the $H\to ZZ\to \ell^+\ell^-\ell^{\prime +}\ell^{\prime -}$ search channel using boosted decision trees to better discriminate between signals and backgrounds and to tame systematic uncertainties in the background rates.