Top-phobic heavy Higgs boson as the 750 GeV diphoton resonance TOP-PHOBIC HEAVY HIGGS BOSON AS the 750 GeV ⋯ SIN KYU KANG and JEONGHYEON SONG

A hint of a new resonance at a mass of 750 GeV has been shown in the diphoton channel of the Run-2 LHC data. The observed signal rate is usually too large to interpret it as a new scalar boson in the context of weakly coupled renormalizable models. One way is to reduce its total decay rate, which is possible if the CP-even heavy Higgs boson H0 in the aligned two Higgs doublet model becomes top-phobic. To ensure sufficient gluon fusion production, we introduce vector-like quarks (VLQ). The Higgs precision data as well as the exclusion limits from no excesses in other resonance searches through Zγ, bb, τ+τ-, and jj channels at the Run-1 LHC are comprehensively studied. In Type I, the top-phobic H0 cannot simultaneously explain the 750 GeV diphoton excess and the Higgs precision data since the same Yukawa couplings of the up-type and down-type VLQs to H0 always make more contribution to the diphoton signal rate of the standard model Higgs boson than that of H0. In Type II, small Yukawa coupling of the up-type VLQ but sizable Yukawa coupling of the down-type VLQ is shown to explain the signal while satisfying other LHC exclusion limits.