Dirac Triplet Extension of the MSSM

TL;DR

This paper investigates a triplet extension of the MSSM with Dirac mass terms, demonstrating it can naturally achieve a 125 GeV Higgs mass with minimal fine-tuning and viable light stop squarks under certain conditions.

Contribution

It introduces a novel triplet extension of the MSSM with Dirac masses, showing it can raise the Higgs mass to 125 GeV without large fine-tuning, similar to singlet models.

Findings

Higgs mass can reach 125 GeV without large fine-tuning.

Viable models have small contributions to the T parameter and light stop squarks.

Light stop masses (~300-450 GeV) are compatible with a compressed spectrum.

Abstract

In this paper we explore extensions of the Minimal Supersymmetric Standard Model involving two $SU(2)_L$ triplet chiral superfields that share a superpotential Dirac mass yet only one of which couples to the Higgs fields. This choice is motivated by recent work using two singlet superfields with the same superpotential requirements. We find that, as in the singlet case, the Higgs mass in the triplet extension can easily be raised to $125\,\text{GeV}$ without introducing large fine-tuning. For triplets that carry hypercharge, the regions of least fine tuning are characterized by small contributions to the $\mathcal T$ parameter, and light stop squarks, $m_{\tilde t_1} \sim 300-450\,\text{GeV}$; the latter is a result of the $\tan\beta$ dependence of the triplet contribution to the Higgs mass. Despite such light stop masses, these models are viable provided the stop-electroweakino spectrum is sufficiently compressed.