Looking for New Naturally Aligned Higgs Doublets at the LHC

TL;DR

This paper explores new symmetry-based mechanisms in the Two Higgs Doublet Model that naturally produce SM-like Higgs behavior without decoupling, and proposes collider signals for heavy Higgs detection at the LHC.

Contribution

It introduces a novel symmetry framework for natural alignment in 2HDM, identifying only three such symmetry realizations and analyzing their collider signatures.

Findings

Three symmetry realizations for natural alignment in 2HDM identified

Heavy Higgs signals predominantly produce third-generation quarks

Collider signals can distinguish natural alignment scenarios during LHC Run-II

Abstract

Since the current LHC Higgs data suggest the couplings of the observed 125 GeV Higgs boson to be close to the Standard Model (SM) expectations, any extended Higgs sector must lead to the so-called SM alignment limit, where one of the Higgs bosons behaves exactly like that of the SM. In the context of the Two Higgs Doublet Model (2HDM), this alignment is often associated with either decoupling of the heavy Higgs sector or accidental cancellations in the 2HDM potential. We present a novel symmetry justification for 'natural' alignment without necessarily decoupling or fine-tuning. We show that there exist only three different symmetry realizations of the natural alignment scenario in 2HDM. We analyze new collider signals for the heavy Higgs sector in the natural alignment limit, which dominantly lead to third-generation quarks in the final state and can serve as a useful observational tool during the Run-II phase of the LHC.