125 GeV Higgs, Type III Seesaw and Gauge-Higgs Unification

TL;DR

This paper explores how a 125 GeV Higgs boson influences new physics models, including type III seesaw and gauge-Higgs unification, to address vacuum stability and predict Higgs mass.

Contribution

It demonstrates that certain new physics scenarios can naturally accommodate a 125 GeV Higgs and lower the vacuum stability bound, linking the Higgs mass to the cutoff scale.

Findings

Type III seesaw allows a 125 GeV Higgs with TeV-scale seesaw.

Effective cutoff at 10^{11} GeV yields a 125 GeV Higgs bound.

Gauge-Higgs unification predicts a Higgs mass around 121 GeV.

Abstract

Recently, both the ATLAS and CMS experiments have observed an excess of events that could be the first evidence for a 125 GeV Higgs boson. This is a few GeV below the (absolute) vacuum stability bound on the Higgs mass in the Standard Model (SM), assuming a Planck mass ultraviolet (UV) cutoff. In this paper, we study some implications of a 125 GeV Higgs boson for new physics in terms of the vacuum stability bound. We first consider the seesaw extension of the SM and find that in type III seesaw, the vacuum stability bound on the Higgs mass can be as low as 125 GeV for the seesaw scale around a TeV. Next we dicuss some alternative new physics models which provide an effective ultraviolet cutoff lower than the Planck mass. An effective cutoff \Lambda \simeq 10^{11} GeV leads to a vacuum stability bound on the Higgs mass of 125 GeV. In a gauge-Higgs unification scenario with five-dimensional flat spacetime, the so-called gauge-Higgs condition allows us to predict a Higgs mass of 125 GeV, with the compactification scale of the extra-dimension being identified as the cutoff scale \Lambda \simeq 10^{11} GeV. Identifying the compactification scale with the unification scale of the SM SU(2) gauge coupling and the top quark Yukawa coupling yields a Higgs mass of 121\pm 2 GeV.