Naturalness and light Higgsinos: why ILC is the right machine for SUSY discovery

Understand

Radiatively-driven natural supersymmetry, a theoretically and experimentally well-motivated framework, centers around the predicted existence of four light, nearly mass-degenerate Higgsinos with mass $\sim 100-200$ GeV (not too far above $m_Z$).

• The small mass splittings amongst the higgsinos, typically 4-20 GeV, results in very little visible energy arising from decays of the heavier higgsinos.
• Given that other SUSY particles are considerably heavy, this makes detection challenging at hadron colliders.
• On the other hand, the clean environment of an electron-positron collider with $\sqrt{s}>2m_{higgsino}$ would enable a decisive search of these required higgsinos, and thus either the discovery or exclusion of natural SUSY.