A natural mechanism for a SM-like Higgs boson in the 2HDM without decoupling

TL;DR

This paper discusses how the two-Higgs doublet model can naturally produce a Higgs boson with properties very similar to the Standard Model Higgs without requiring the heavy decoupling of additional particles, through symmetry considerations.

Contribution

It explores the Higgs alignment limit in the 2HDM, showing how approximate symmetries can naturally lead to a SM-like Higgs without decoupling.

Findings

Higgs alignment can be achieved naturally via symmetries

Softly-broken symmetries extend to Yukawa sector

SM-like Higgs properties arise without decoupling

Abstract

The properties of the Higgs boson discovered at the Large Hadron Collider are very well described by the Standard Model (SM). Thus, any theory that invokes an extended Higgs sector must explain why the neutral scalar observed at the LHC so closely resembles the SM Higgs boson. In this talk, I review the Higgs alignment limit, in which one neutral scalar state of the Higgs sector is SM-like. An approximate Higgs alignment can be achieved "naturally" either via decoupling or via an approximate symmetry. Using the two-Higgs doublet model as a prototype for an extended Higgs sector, I examine the symmetries of the scalar potential and their soft breakings that may be responsible for the SM-like properties of the observed Higgs boson, and I demonstrate how to extend such (softly-broken) symmetries to the Yukawa sector of the model.