Diboson excess in the Higgs singlet and vectorlike quark models

Diboson resonance with mass of 1.8-2 TeV is reported successively by CMS and ATLAS experiments in proton-proton collisions at s=8 TeV. We investigate the potentiality of Higgs singlet as the TeV resonance. The challenges of low production cross section and high width for a fundamental scalar could be got over by three factors: (1) larger Yukawa couplings, (2) larger number of heavy quarks and (3) smaller mixing angle with standard model Higgs. We find that the required factors could be realized in the framework of two vectorlike triplet quarks (VLTQs) and the resulting production cross section and decay fraction of heavy Higgs σ(pp→H)×BR(H→W+W-+ZZ) can be of O(10) fb when masses of new heavy quarks are 1 TeV, the values of Yukawa couplings are around 3 and the mixing angle is sinθ∼0.11. We also find that the SM Higgs production and its decay in the process pp→h→γγ could be still consistent with current data when a color-triplet scalar (3,3)1/3 is considered. Furthermore, we study the product of VLTQ-pair production cross section and the BRs of VLTQ decays, and find that the cross sections in the decay channels, such as u4,5→bW+, d5→tW- and d4→bh(Z) could be 7-17 fb at 13 TeV LHC.