Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in 21$\,$fb$^{-1}$ of pp collisions at $\sqrt{s}=8\,$TeV with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three leptons (electrons or muons) and missing transverse momentum is presented. The analysis is based on 20.7]$\,$fb$^{-1}$ of proton-proton collision data delivered by the LHC at $\sqrt{s}\,$=$\,$8$\,$TeV and recorded by the ATLAS detector. No excess above the Standard Model expectation is observed in six signal regions that are either enriched or depleted in $Z$-boson decays. Limits are placed at the 95% confidence level on the masses of the charginos and neutralinos in simplified supersymmetric models. Chargino and heavy neutralino masses are excluded up to 600$\,$GeV if these particles decay through sleptons and up to 315$\,$GeV in cases where they decay via gauge bosons to a massless lightest neutralino.