Low scale composite Higgs model and 1.8 ∼2 TeV diboson excess

Abstract

We consider a simple solution to explain the recent diboson excess observed by ATLAS and CMS Collaborations in models with custodial symmetry [Formula: see text]. The [Formula: see text] triplet vector boson [Formula: see text] with mass range of [Formula: see text] TeV would be produced through the Drell–Yan process with sizable diboson decay branching to account for the excess. The other [Formula: see text] bidoublet axial vector boson [Formula: see text] would cancel all deviations of electroweak obervables induced by [Formula: see text] even if the SM fermions mix with some heavy vector-like (composite) fermions which couple to [Formula: see text] (“nonuniversally partially composite”), therefore allows arbitrary couplings between each SM fermion and [Formula: see text]. We present our model in the “General Composite Higgs” framework with [Formula: see text] breaking at scale [Formula: see text] and demand the first Weinberg sum rule and positive gauge boson form factors as the theoretical constraints. We find that our model can fit the diboson excess very well if the left-handed SM light quarks, charged leptons and tops have zero, zero/moderately small and moderate/large composite components for reasonable values of [Formula: see text] and [Formula: see text]. The correlation between tree level [Formula: see text] parameter and the [Formula: see text] suggest a large [Formula: see text] contribution to [Formula: see text] and it is indeed a [Formula: see text] effect in our parameter space which provides a strong hint for our scenario if this diboson excess is confirmed by the [Formula: see text] TeV LHC Run II.