Search for chargino-neutralino pair production in final states with three leptons and missing transverse momentum in $\sqrt{s}$ = 13 TeV p-p collisions with the ATLAS detector

A search for chargino-neutralino pair production in three-lepton final states with missing transverse momentum in $\sqrt{s}$ = 13 TeV p-p collisions with the ATLAS detector is presented. Strategies targeting decays with intermediate $W$, $Z$ bosons or intermediate $W$, Higgs ($h$) bosons are discussed. The search targets a model in which the chargino ($\tilde{\chi}^{\pm}_{1}$) and next-to-lightest neutralino ($\tilde{\chi}^{0}_{2}$) are mass degenerate. The $\tilde{\chi}^{\pm}_{1}$ decays to a lightest neutralino ($\tilde{\chi}^{0}_{1}$) and a $W$ boson, while the $\tilde{\chi}^{0}_{2}$ decays to a $\tilde{\chi}^{0}_{1}$ and a $Z$ or Higgs ($h$) boson. Only leptonic decays of the Standard Model bosons are considered. Strategies targeting scenarios where the mass difference between the $\tilde{\chi}^{\pm}_{1}$/$\tilde{\chi}^{0}_{2}$ and $\tilde{\chi}^{0}_{1}$ is above the $Z$-boson mass, with on-shell $W$ and $Z$ bosons or on-shell $W$ and $h$ bosons, and scenarios where the mass difference is between 10-90 GeV, with off-shell $W^{*}$ and $Z^{*}$ bosons, are discussed. A dataset corresponding to an integrated luminosity of 139 fb$^{-1}$ is used and no significant excess is found in data with respect to the Standard Model predictions. Exclusion limits at 95% confidence level are set on a simplified model of pure wino $\tilde{\chi}^{\pm}_{1}\tilde{\chi}^{0}_{2}$ pair production. Models with $\tilde{\chi}^{\pm}_{1}$ and $\tilde{\chi}^{0}_{2}$ are excluded up to 640 GeV for decays via on-shell $W$ and $Z$ bosons and massless $\tilde{\chi}^{0}_{1}$, up to 300 GeV for decays via off-shell $W^{*}$ and $Z^{*}$ bosons, and up to 185 GeV for on-shell $W$ and $h$ bosons and $\tilde{\chi}^{0}_{1}$ masses less than 20 GeV.