The breaking of the $SU(2)_L\times U(1)_Y$ symmetry: The 750 GeV resonance at the LHC and perturbative unitarity

TL;DR

This paper discusses how a 750 GeV scalar resonance, potentially explaining the LHC di-photon excess, must be part of a model with additional scalars to maintain perturbative unitarity, favoring the Georgi-Machacek model.

Contribution

It identifies the Georgi-Machacek model as the simplest framework consistent with the 750 GeV resonance and perturbative unitarity constraints.

Findings

The 750 GeV resonance implies additional scalar states.

Perturbative unitarity constrains the scalar sector.

The Georgi-Machacek model fits the data and theoretical requirements.

Abstract

If the di-photon excess at 750 GeV hinted by the 2015 data at the LHC is explained in terms of a scalar resonance participating in the breaking of the electro-weak symmetry, this resonance must be accompanied by other scalar states for perturbative unitarity in vector boson scattering to be preserved. The simplest set-up consistent with perturbative unitarity and with the data of the di-photon excess is the Georgi-Machacek model.