Supersymmetric Naturalness Beyond MSSM

TL;DR

This paper suggests that physics beyond the MSSM might better explain LHC data, showing that less fine-tuning is possible with higher cut-off scales, indicating new directions for supersymmetric theories.

Contribution

It demonstrates that theories with a higher cut-off scale can achieve naturalness with less fine-tuning, challenging the minimal MSSM paradigm.

Findings

Lowering the cut-off scale reduces fine-tuning.

Natural supersymmetric theories with multi-TeV spectra are possible at ~100 TeV scale.

Special parameter behaviors further decrease fine-tuning.

Abstract

The experiments at the Large Hadron Collider (LHC) have pushed the limits on masses of supersymmetric particles beyond the $\sim$TeV scale. This compromises naturalness of the simplest supersymmetric extension of the Standard Model, the minimal supersymmetric Standard Model (MSSM). In this paper we advocate that perhaps the current experimental data are actually hinting towards the physics beyond MSSM. To illustrate this, we treat MSSM as a low energy limit of a more fundamental yet unspecified theory at a scale $\Lambda$, and compute the fine-tuning measure $\Delta$ for generic boundary conditions on soft SUSY breaking parameters and various cut-off scales. As a general trend we observe reduction in fine-tuning together with lowering $\Lambda$. In particular, perfectly natural [$\Delta \lesssim \mathcal{O}(10)$] theories with a multi-TeV spectrum of supersymmetric particles and consistent with all current observations can be obtained for $\Lambda \sim \mathcal{O}(100)$TeV. The lowering of the fine-tuning for large cut-off scales can also be observed in theories exhibiting special quasi-fixed point behaviours of parameters. Our observations call for a more throughout exploration of possible alternative ultraviolet completions of MSSM.