Higgs Boson Mass Bounds in the Standard Model with Type III and Type I Seesaw

TL;DR

This paper explores how type III and type I seesaw mechanisms, involving new fermion fields, influence the bounds on the Standard Model Higgs boson mass, especially near the TeV scale, through renormalization group analysis.

Contribution

It computes the renormalization group equations for type III seesaw and identifies parameter regions that extend the Higgs mass window and unify stability and perturbativity bounds.

Findings

Higgs mass window extended to 125-174 GeV with type III seesaw near TeV scale.

Regions where vacuum stability and perturbativity bounds merge for large Yukawa couplings.

Comparison of bounds and effects between type III and type I seesaw mechanisms.

Abstract

In type III seesaw utilized to explain the observed solar and atmospheric neutrino oscillations the Standard Model (SM) particle spectrum is extended by introducing three SU(2)_L triplet fermion fields. This can have important implications for the SM Higgs boson mass (M_H) bounds based on vacuum stability and perturbativity arguments. We compute the appropriate renormalization group equations for type III seesaw, and then proceed to identify regions of the parameter space such that the SM Higgs boson mass window is enlarged to 125 GeV < M_H < 174 GeV, with the type III seesaw scale close to TeV. We also display regions of the parameter space for which the vacuum stability and perturbativity bounds merge together for large neutrino Yukawa couplings. Comparison with type I seesaw is also presented.