On the extension of the SM through a scalar quadruplet

TL;DR

This paper explores extending the Standard Model with a scalar quadruplet, analyzing theoretical constraints, scalar masses, and Higgs couplings to understand potential new physics effects.

Contribution

It provides a detailed analysis of the scalar potential, unitarity, and boundedness conditions for the extended model with a scalar quadruplet, including mass and coupling computations.

Findings

Derived unitarity conditions for the scalar potential

Established bounded-from-below conditions numerically

Calculated new scalar masses and Higgs couplings

Abstract

We consider the extension of the Standard Model (SM) through a scalar quadruplet with hypercharge either $1/2$ or $3/2$; in the first case, we assume $CP$ invariance of the scalar potential (SP). We write down the unitarity conditions on the SP. We use a partly numerical method to find the bounded-from-below conditions on the SP. We determine the masses of the new scalars of the model. We compute the three- and four-Higgs couplings and compare them to the ones of the SM.