Tackling light higgsinos at the ILC

Understand

In supersymmetric extensions of the Standard Model, higgsino-like charginos and neutralinos are preferred to have masses of the order of the electroweak scale by naturalness arguments.

• Such light $\widetilde{\chi}^0_1$, $\widetilde{\chi}^0_2$ and $\widetilde{\chi}^{\pm}_1$ states can be almost mass degenerate, and their decays are then difficult to observe at colliders.
• In addition to the generic naturalness argument, light higgsinos are well motivated from a top-down perspective.
• For instance, they arise naturally in certain models of hybrid gauge-gravity mediation.