Natural MSSM after the LHC 8 TeV run

TL;DR

This paper assesses how recent LHC SUSY searches constrain natural MSSM scenarios, showing most natural points are already excluded, impacting the model's viability and fine-tuning considerations.

Contribution

It provides a detailed analysis of LHC search impacts on various natural MSSM scenarios, including fine-tuning and phenomenological implications.

Findings

Most natural MSSM points are excluded by LHC data.

Including other constraints further reduces the natural parameter space.

Remaining allowed points tend to have higher fine-tuning.

Abstract

We investigate the impact of direct LHC SUSY searches on the parameter space of three natural scenarios in the MSSM. In the first case the spectrum consists of light stops, sbottoms, and Higgsino-like neutralinos, while the other particles are assumed to be out of the experimental reach. In the second case we consider an additional light gluino. Finally we study a more complex spectrum comprising also light sleptons, a wino-like chargino, and a bino-like neutralino. We simulate in detail three LHC searches: stop production at ATLAS with 20.7/fb, CMS 11.7/fb inclusive search for squarks and gluinos with the variable \alpha_T, and CMS 9.2/fb electroweak production with 3 leptons in the final state. For each point in our scans we calculate the exclusion likelihood due to the individual searches and to their statistical combination. We calculate the fine-tuning measure of the points allowed by the LHC and the implications for the Higgs mass and other phenomenological observables: Higgs signal rates, the relic density, BR(Bs --> \mu^+\mu^-), BR(B --> Xs \gamma), and the spin-independent neutralino-proton scattering cross section. We find that points with acceptable levels of fine-tuning are for the most part already excluded by the LHC and including the other constraints further reduces the overall naturalness of our scenarios.