Naturalness of the Non-Universal MSSM in the light of the recent Higgs results

TL;DR

This paper investigates the naturalness of the non-universal MSSM in light of recent Higgs mass measurements, showing that certain non-universal gaugino mass configurations can significantly reduce fine-tuning.

Contribution

It demonstrates that non-universal gaugino masses can lower fine-tuning in the MSSM, aligning with recent Higgs results and experimental constraints.

Findings

Fine-tuning can be reduced to O(10) for a 125 GeV Higgs.

Lightest neutralino can be lighter than 400 GeV with low fine-tuning.

Gluino mass must be above 1.5 TeV for natural scenarios.

Abstract

We analyse the naturalness of the Minimal Supersymmetric Standard Model (MSSM) in the light of recent LHC results from the ATLAS and CMS experiments. We study non-universal boundary conditions for the scalar and the gaugino sector, with fixed relations between some of the soft breaking parameters, and find a significant reduction of fine-tuning for non-universal gaugino masses. For a Higgs mass of about 125 GeV, as observed recently, we find parameter regions with a fine-tuning of O(10), taking into account experimental and theoretical uncertainties. These regions also survive after comparison with simplified model searches in ATLAS and CMS. For a fine-tuning less than 20 the lightest neutralino is expected to be lighter than about 400 GeV and the lighter stop can be as heavy as 3.5 TeV. On the other hand, the gluino mass is required to be above 1.5 TeV. For non-universal gaugino masses, we discuss which fixed GUT scale ratios can lead to a reduced fine-tuning and find that the recent Higgs results have a strong impact on which ratio is favoured. We also discuss the naturalness of GUT scale Yukawa relations, comparing the non-universal MSSM with the CMSSM.