Radiative natural supersymmetry with mixed axion/higgsino cold dark matter

TL;DR

This paper proposes a radiative natural supersymmetry model that achieves low fine-tuning with TeV-scale top squarks and a 125 GeV Higgs, while also addressing dark matter through an axion-higgsino mixture.

Contribution

It introduces a radiative natural SUSY framework with high-scale Higgs mass parameters, enabling low fine-tuning and consistent dark matter predictions including axion and higgsino components.

Findings

Achieves 5-10% electroweak fine-tuning with TeV-scale top squarks.

Predicts a 125 GeV Higgs boson consistent with LHC measurements.

Suggests dark matter as an admixture of axions and higgsinos, potentially detectable.

Abstract

Models of natural supersymmetry seek to solve the little hierarchy problem by positing a spectrum of light higgsinos \lesssim 200 GeV and light top squarks \lesssim 500 GeV along with very heavy squarks and TeV-scale gluinos. Such models have low electroweak finetuning and are safe from LHC searches. However, in the context of the MSSM, they predict too low a value of m(h) and the relic density of thermally produced higgsino-like WIMPs falls well below dark matter (DM) measurements. Allowing for high scale soft SUSY breaking Higgs mass m_{H_u}> m_0 leads to natural cancellations during RG running, and to radiatively induced low finetuning at the electroweak scale. This model of radiative natural SUSY (RNS), with large mixing in the top squark sector, allows for finetuning at the 5-10% level with TeV-scale top squarks and a 125 GeV light Higgs scalar h. If the strong CP problem is solved via the PQ mechanism, then we expect an axion-higgsino admixture of dark matter, where either or both the DM particles might be directly detected.