Scenarii for interpretations of the LHC diphoton excess: two Higgs doublets and vector-like quarks and leptons

TL;DR

This paper investigates various theoretical models involving two Higgs doublets and vector-like fermions to explain the 750 GeV diphoton excess observed at the LHC, highlighting the need for additional particles beyond minimal models.

Contribution

It demonstrates that minimal two-Higgs doublet models cannot explain the excess and proposes that vector-like quarks or leptons enhance Higgs couplings to photons and gluons.

Findings

Minimal models are insufficient to explain the diphoton excess.

Additional vector-like fermions can enhance Higgs couplings.

Enhanced couplings can account for the observed resonance.

Abstract

An evidence for a diphoton resonance at a mass of 750 GeV has been observed in the data collected at the LHC run at a center of mass energy of 13 TeV. We explore several interpretations of this signal in terms of Higgs-like resonances in a two-Higgs doublet model and its supersymmetric incarnation, in which the heavier CP-even and CP-odd states present in the model are produced in gluon fusion and decay into two photons through top quark loops. We show that one cannot accommodate the observed signal in the minimal versions of these models and that an additional particle content is necessary. We then consider the possibility that vector-like quarks or leptons strongly enhance the heavy Higgs couplings to photons and eventually gluons, without altering those of the already observed 125 GeV state.