Triplet Extended MSSM: Fine Tuning vs Perturbativity and Experiment

TL;DR

This paper evaluates the Triplet Extended MSSM's compatibility with experimental data, focusing on perturbativity, fine-tuning, and Higgs observables, revealing a tension between naturalness and experimental constraints.

Contribution

It provides a detailed analysis of the TESSM's parameter space, including two-loop beta functions, and assesses its phenomenological viability against current collider and flavor physics data.

Findings

Perturbativity is maintained for |λ| < 1.34.

Fine-tuning is reduced for |λ| ≳ 0.8.

Experimental data favors small |λ| despite naturality considerations.

Abstract

In this study we investigate the phenomenological viability of the $Y=0$ Triplet Extended Supersymmetric Standard Model (TESSM) by comparing its predictions with the current Higgs data from ATLAS, CMS, and Tevatron, as well as the measured value of the $B_s\to X_s \gamma$ branching ratio. We scan numerically the parameter space for data points generating the measured particle mass spectrum and also satisfying current direct search constraints on new particles. We require all the couplings to be perturbative up to the scale $\Lambda_{\rm UV}=10^4$ TeV, by running them with newly calculated two loop beta functions, and find that TESSM retains perturbativity as long as $\lambda$, the triplet coupling to the two Higgs doublets, is smaller than 1.34 in absolute value. For $|\lambda|\gtrsim 0.8$ we show that the fine-tuning associated to each viable data point can be greatly reduced as compared to values attainable in MSSM. Finally, we perform a fit by taking into account 58 Higgs physics observables along with $\mathcal{B}r(B_s\to X_s \gamma)$, for which we calculate the NLO prediction within TESSM. We find that, although naturality prefers a large $|\lambda|$, the experimental data disfavors it compared to the small $|\lambda|$ region, because of the low energy observable $\mathcal{B}r(B_s\to X_s \gamma)$.