Search for direct-slepton and direct-chargino production in final states with two opposite-sign leptons, missing transverse momentum and no jets in 20/fb of pp collisions at sqrt(s) = 8 TeV with the ATLAS detector

Searches for the electroweak production of pairs of sleptons or charginos decaying into final states with two leptons, missing transverse momentum and no reconstructed jets are performed using 20.3 fb-1 of proton-proton collision data at sqrt(s) = 8 TeV recorded with the ATLAS experiment at the Large Hadron Collider. No significant excesses are observed with respect to the prediction from Standard Model processes. Limits are set on the masses of the slepton and of the lightest chargino for different lightest-neutralino mass hypotheses. In scenarios where sleptons decay directly into the lightest neutralino and a charged lepton, common values for left and right-handed slepton masses between 90 GeV and 320 GeV are excluded at 95% confidence level for a massless neutralino. In the scenario of chargino pair production, with wino-like charginos decaying into the lightest neutralino via an intermediate slepton, chargino masses between 130 GeV and 450 GeV are excluded at 95% confidence level for a 20 GeV neutralino. In the scenario of chargino pair production followed by the C1 -> WN1 decay, the excluded cross-section is above the model cross-section by a factor 1.9-2.8 in the C1 mass range of 100-190 GeV and then degrades gradually to 4.7 when reaching a C1 mass of 250 GeV.