LHC Higgs signatures from extended electroweak gauge symmetry

Abstract

We study LHC Higgs signatures from the extended electroweak gauge symmetry SU(2) x SU(2) x U(1). Under this gauge structure, we present an effective UV completion of the 3-site moose model with ideal fermion delocalization, which contains two neutral Higgs states (h, H) and three new gauge bosons (W', Z'). We study the unitarity, and reveal that the exact E^2 cancellation in the longitudinal WW scattering amplitudes is achieved by the joint role of exchanging both spin-1 new gauge bosons and spin-0 Higgs bosons. We identify the lighter Higgs state h with mass 125GeV, and derive the unitarity bound on the mass of heavier Higgs boson H. The parameter space of this model is highly predictive. We study the production and decay signals of this 125GeV Higgs boson h at the LHC. We demonstrate that the h Higgs boson can naturally have enhanced signals in the diphoton channel $gg \to h \to\gamma\gamma$, while the events rates in the reactions $gg \to h \to WW^*$ and $gg \to h \to ZZ^*$ are generally suppressed relative to the SM expectation. Searching the h Higgs boson via associated productions and vector boson fusions are also discussed for our model. We further analyze the LHC signals of the heavier Higgs boson H as a distinctive new physics discriminator from the SM. For wide mass-ranges of H, we derive constraints from the existing LHC searches, and study the discovery potential of H at the LHC(8TeV) and LHC(14TeV).