750 GeV Diphoton Resonance in a Vector-like Extension of Hill Model

TL;DR

This paper investigates the 750 GeV diphoton excess using a Hill Model extension with vector-like fermions, identifying parameter space consistent with observed signals and theoretical constraints.

Contribution

It introduces a vector-like fermion extension of the Hill Model to explain the 750 GeV diphoton resonance, analyzing production and decay mechanisms within experimental bounds.

Findings

Diphoton cross section can reach about 6 fb at 13 TeV LHC.

Heavier vector-like fermions require smaller mixing angles.

Mixing angle constrained within | heta|  0.15 for perturbative Yukawa couplings.

Abstract

In this paper, we study the recent 750 GeV diphoton excess in the Hill Model with vector-like fermions, in which the singlet-like Higgs boson is chosen as 750 GeV resonance and is mainly produced by the gluon fusion through vector-like top and bottom quarks. Meanwhile its diphoton decay rate is greatly enhanced by the vector-like lepton. Under the current experimental and theoretical constraints, we present the viable parameter space that fits the 750 GeV diphoton signal strength at 13 TeV LHC. We find that the heavier vector-like fermion masses are, the smaller mixing angle $\theta$ is required. The mixing angle of singlet and doublet Higgs bosons is constrained within $|\sin\theta| \lesssim 0.15$ in the condition of the perturbative Yukawa couplings. In the allowed parameter space, the 750 GeV diphoton cross section can be maximally enhanced to about 6 fb at 13 TeV LHC.