Heavy Higgs boson coupled to vectorlike quarks: Strong CP problem and search prospects at the 14 TeV LHC

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 vectorlike quarks enhancing its production cross section whose dominant decays are into weak bosons. The masses of the vectorlike 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 -> ZZ -> l(+)l(-)l'(+)l'(-) search channel using boosted decision trees to better discriminate between signals and backgrounds and to tame systematic uncertainties in the background rates.