Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in $\sqrt{s}$ = 13 TeV $pp$ collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splitting near the electroweak scale decaying via on-shell $W$ and $Z$ bosons is presented in a three-lepton final state. The analyzed proton-proton collision data taken at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV was collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$^{-1}$. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory frame variables, is performed. The two excesses observed with the 2015-2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are consistently reproduced. Results with the full dataset are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at 95% confidence level on simplified models of chargino-neutralino pair production for masses between 100 GeV and 350 GeV.