Natural Supersymmetry without Light Higgsinos
In this study, we present a mechanism that allows a large Higgsino mass without large fine-tuning. The Higgs is a pseudo-Nambu-Goldstone boson (PNGB) of the global symmetry breaking pattern SO(5)→SO(4). Because of the PNGB nature of the light Higgs, the SO(5) invariant Higgsino mass does not directly contribute to the Higgs mass. Large couplings in the Higgs sector that spontaneously breaks SO(5) minimize the tuning, and are also motivated by the requirements of generating a sufficiently large Higgs quartic coupling and of maintaining a natural approximate global SO(5) symmetry. When these conditions are imposed, theories of this type predict heavy Higgsinos. This construction differs from composite Higgs models in that no new particles are introduced to form complete SO(5) multiplets involving the top quark—the stop is the only top partner. Compatibility with Higgs coupling measurements requires cancellations among contributions to the Higgs mass-squared parameter at the 10% level. An important implication of this construction is that the compressed region of stop and sbottom searches can still be natural.