Scrutinizing Vacuum Stability in IDM with Type-III Inverse seesaw

TL;DR

This paper investigates the stability of the electroweak vacuum in an extended Standard Model with an inert Higgs doublet and Type-III inverse seesaw neutrino mass mechanism, analyzing the effects of triplet fermions and gauge couplings.

Contribution

It provides a detailed two-loop analysis of vacuum stability considering multiple triplet fermion generations and their impact on gauge coupling running and model parameters.

Findings

Two-generation extension favors Planck scale stability.

Bounds on Higgs quartic and Yukawa couplings are established.

Phenomenological implications at LHC are discussed.

Abstract

We consider the extension of the Standard Model (SM) with an inert Higgs doublet that also contains two or three sets of $SU(2)_L$ triplet fermions with hypercharge zero and analyze the stability of electroweak vacuum for the scenarios. The model represents a Type-III inverse seesaw mechanism for neutrino mass generation with a Dark matter candidate.An effective potential approach calculation with two-loop beta function have been carried out in deciding the fate of the electroweak vacuum. Weak gauge coupling $g_2$ shows a different behaviour as compared to the Standard Model. The modified running of $g_2$, along with the Higgs quartic coupling and Type-III Yukawa couplings become crucial in determining the stability of electroweak vacuum. The interplay between two and three generations of such triplet fermions reveals that extensions with two generations is favoured if we aspire for Planck scale stability. Bounds on the Higgs quartic couplings, Type-III Yukawa and number of triplet fermion generations are drawn for different mass scale of Type-III fermions. The phenomenologies of inert doublet and Type-III fermions at the LHC and other experiments are commented upon.