ATLAS sensitivity to winos and higgsinos with a highly compressed mass spectrum at the HL-LHC

This note presents the prospects of two searches for direct chargino and neutralino production ($\tilde{\chi}_{1}^{\pm}\tilde{\chi}_{1}^{\pm}$, $\tilde{\chi}_{1}^{\pm}\tilde{\chi}_{2}^{0}$ and $\tilde{\chi}_{1}^{\pm}\tilde{\chi}_{1}^{0}$), in highly compressed mass scenarios, in proton-proton collisions at a centre-of-mass energy of 14$\mathrm{TeV}$. The first is a disappearing track search that investigates chargino production scenarios, where the chargino decays via a neutralino and a very soft pion, which is not reconstructed. The small mass splitting between the chargino and neutralino implies that the chargino has a significant lifetime and decays within the innermost tracking detector. The second is a two soft lepton search that investigates scenarios where the second lightest neutralino decays to the lightest neutralino and an off-shell $Z$-boson, giving rise to two soft leptons. The results of both searches are interpreted in pure-wino and pure-higgsino scenarios. The reach for these scenarios at the high-luminosity phase of the LHC with an assumed integrated luminosity of 3000$\mathrm{fb}^{-1}$ is presented and significantly extends beyond the current Run 2 limits of the respective analyses.