Higgs-Sector Predictions from Maximally Symmetric multi-Higgs Doublet Models

TL;DR

This paper explores maximally symmetric multi-Higgs doublet models, which predict Higgs sector properties beyond the Standard Model, with potential testability at colliders, by leveraging an $ ext{Sp}(2n)$ symmetry to derive scalar spectra and couplings.

Contribution

It introduces a framework based on $ ext{Sp}(2n)$ symmetry for multi-Higgs models, providing explicit predictions for scalar spectra and couplings with minimal input parameters.

Findings

Predictions for scalar mass spectra in MS-2HDM and MS-3HDM.

SM-like Higgs couplings derived from symmetry considerations.

Models maintain natural alignment and unification up to the Planck scale.

Abstract

Maximally Symmetric $n$-Higgs Doublet Models (MS-$n$HDMs)define very economic settings that enable sharp Higgs-sector predictions beyond the Standard Model (SM) potentially testable at high-energy colliders. The scalar potential of a MS-$n$HDM obeys an $\mathrm{Sp(2}n)$ symmetry, which is softly broken by bilinear scalar masses and explicitly by hypercharge and Yukawa couplings through renormalisation-group effects. The $\mathrm{Sp(2}n)$ also ensures natural SM alignment and allows for quartic coupling unification up to the Planck scale. As typical examples, we consider maximally symmetric realisations of the Type-II 2HDM and the Type-V 3HDM. We show how in terms of a few input parameters, definite predictions for the entire scalar mass spectrum of the MS-2HDM and MS-3HDM are obtained, including the SM-like Higgs-boson couplings to the gauge bosons and fermions.