Vector-like leptons and extra gauge symmetry for the natural Higgs boson

TL;DR

This paper proposes a model with vector-like leptons and an extra gauge symmetry to naturally explain the 125 GeV Higgs mass without fine-tuning, and explores implications for gauge unification and Higgs decay enhancements.

Contribution

Introduction of vector-like leptons and a non-Abelian gauge extension to achieve a natural Higgs mass and address high-energy behavior, with potential for Higgs decay rate enhancements.

Findings

Higgs mass explained with ~500 GeV stop mass and large Yukawa coupling

Extra leptons allow for less stringent mass bounds and radiative corrections

Gauge extension maintains unification and controls Yukawa coupling growth

Abstract

For raising the radiative Higgs mass without a serious fine-tuning in the Higgs sector, we introduce vector-like lepton doublets and neutral singlets {L,L^c; N,N^c}, and consider their order one Yukawa coupling to the Higgs, W \supset y_NLh_uN^c. The 125 GeV Higgs mass can be naturally explained with the stop mass squared of ~(500 GeV)^2 and even without the "A-term" contributions. It is possible because of the quartic power of y_N in the radiative Higgs mass correction, and much less stringent mass bounds on extra leptonic matter. In order to avoid blowup of y_N at higher energy scales, a non-Abelian gauge extension of the MSSM is attempted, under which {L,L^c; N,N^c} are charged, while all the ordinary MSSM superfields remain neutral. We discuss the gauge coupling unification. This mechanism can be applied also for enhancing h^0 \rightarrow \gamma\gamma with W \supset y_EL^ch_uE, if the charged lepton singlets {E,E^c} are also introduced.