Explaining 750 GeV diphoton excess from top/bottom partner cascade decay in two-Higgs-doublet model extension

TL;DR

This paper explains the 750 GeV diphoton excess using a two-Higgs-doublet model with top/bottom partners and charged scalars, showing it can produce the observed signal within current LHC constraints.

Contribution

It introduces a Zee-Babu extended two-Higgs-doublet model with top/bottom partners to explain the diphoton excess, highlighting the role of charged scalars in enhancing the decay rate.

Findings

The heavy CP-even Higgs can be produced via top/bottom partner decays.

Charged scalars significantly enhance the diphoton decay rate.

The model can fit the observed excess within LHC constraints.

Abstract

In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu extension of the two-Higgs-doublet model by introducing a top partner ($T$)/bottom partner ($B$). In the alignment limit, the 750 GeV resonance is identified as the heavy CP-even Higgs boson ($H$), which can be sizably produced via the QCD process $pp \to T\bar{T}$ or $pp \to B\bar{B}$ followed by the decay $T\to Ht$ or $B \to Hb$. The diphoton decay rate of $H$ is greatly enhanced by the charged singlet scalars predicted in the Zee-Babu extension and the total width of $H$ can be as large as 7 GeV. Under the current LHC constraints, we scan the parameter space and find that such an extension can account for the observed diphoton excess.