Fixed point scenario in the Two Higgs Doublet Model inspired by degenerate vacua

TL;DR

This paper investigates the renormalisation group flow in a two Higgs doublet model inspired by the multiple point principle, analyzing Higgs spectra, couplings, and implications for Higgs production at the LHC.

Contribution

It introduces a MPP-inspired 2HDM with quasi-fixed points, providing new insights into Higgs mass bounds and collider phenomenology.

Findings

Quasi-fixed points emerge for large top Yukawa couplings.

The model predicts an upper bound on the lightest Higgs mass.

Enhanced Higgs production at the LHC due to larger top coupling.

Abstract

We consider the renormalisation group flow of Higgs and Yukawa couplings within the simplest non--supersymmetric two Higgs doublet extension of the Standard Model (SM). In this model the couplings are adjusted so that the multiple point principle (MPP) assumption, which implies the existence of a large set of degenerate vacua at some high energy scale $\Lambda$, is realised. When the top quark Yukawa coupling at the scale $\Lambda$ is large, the solutions of RG equations in this MPP inspired 2 Higgs Doublet Model (2HDM) converge to quasi--fixed points. We analyse the Higgs spectrum and couplings in the quasi--fixed point scenario and compute a theoretical upper bound on the lightest Higgs boson mass. When the scale $\Lambda$ is low, the coupling of the SM--like Higgs scalar to the top quark can be significantly larger in the considered model than in the SM, resulting in the enhanced production of Higgs bosons at the LHC.