Supersymmetry remains one of the best motivated and most extensively studied extensions of the Standard Model. Supersymmetric scenarios with compressed mass spectra offer natural solutions to several Standard Model shortcomings, but are challenging due to their subtle experimental signatures. We present recent searches for higgsino production with the ATLAS experiment using the full Run 2 dataset, aiming to close the sensitivity gap between LEP and the LHC for mass splittings of 0.1–3 GeV. New developments in lepton identification—extending down to transverse momenta of 0.5–1 GeV—are employed to target promptly decaying higgsinos. Meanwhile, more long-lived higgsinos are addressed by reconstructing soft pions from their decays or chargino tracklets for the most long-lived scenarios. These search results establish some of the most stringent mass limits to date on compressed supersymmetric scenarios.

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