Natural SUSY at the ILC: from MZ to the GUT scale

The most basic requirement for naturalness in supersymmetric models is theexistence of rather light partners of the Higgs boson, the Higgsinos, atmasses not too far above M_Z. Despite the pressure from LHC data on the simplesthigh-scale models (like the cMSSM), such light Higgsinos can still berealised in different types of GUT-scale models from NUHM2 to mirageunification models. The ILC will offer the unique discovery potentialfor the elusive higgsino particles and allow for precision measurementsof their properties. In this contribution, prospects for the achievableprecisions for masses, the very small mass splittings and polarised productioncross sections will be presented. Based on these, we studied the possibilities todetermine the SUSY parameters at the weak scale, and to extrapolate theirrunning to the GUT scale. We will discuss the prospects to therebydifferentiate between various GUT-scale models and SUSY breaking schemes andto predict the masses of the remaining SUSY particles. In particular thelatter could provide important guidance for the energy scale of the next hadron collider after the LHC