Precise determination of the Higgs mass in supersymmetric models with vectorlike tops and the impact on naturalness in minimal GMSB

TL;DR

This paper provides a highly precise calculation of the Higgs mass in supersymmetric models with vectorlike tops, highlighting the importance of threshold and two-loop corrections, and assesses the impact on naturalness within a GMSB framework.

Contribution

It introduces comprehensive one- and two-loop corrections, including threshold effects, to improve Higgs mass predictions in supersymmetric models with vectorlike tops, and evaluates electroweak fine-tuning in a UV-complete GMSB scenario.

Findings

Threshold corrections significantly affect Higgs mass predictions.

Two-loop effects can alter the Higgs mass by up to 10 GeV in certain parameter regions.

Gluino mass limits are more critical for fine-tuning than Higgs mass constraints.

Abstract

We present a precise analysis of the Higgs mass corrections stemming from vectorlike top partners in supersymmetric models. We reduce the theoretical uncertainty compared to previous studies in the following aspects: (i) including the one-loop threshold corrections to SM gauge and Yukawa couplings due to the presence of the new states to obtain the $\bar{\text{DR}}$ parameters entering all loop calculations, (ii) including the full momentum dependence at one-loop, and (iii) including all two-loop corrections but the ones involving $g_1$ and $g_2$. We find that the additional threshold corrections are very important and can give the largest effect on the Higgs mass. However, we identify also parameter regions where the new two-loop effects can be more important than the ones of the MSSM and change the Higgs mass prediction by up to 10 GeV. This is for instance the case in the low $\tan\beta$, small $M_A$ regime. We use these results to calculate the electroweak fine-tuning of an UV complete variant of this model. For this purpose, we add a complete $\textbf{10}$ and $\bar{\textbf{10}}$ representation of $SU(5)$ to the MSSM particle content. We embed this model in minimal Gauge Mediated Supersymmetry Breaking and calculate the electroweak fine-tuning with respect to all important parameters. It turns out that the limit on the gluino mass becomes more important for the fine-tuning than the Higgs mass measurements which is easily to satisfy in this setup.