Search for direct top squark pair production in final states with two leptons in $\sqrt{s} = 8$ TeV pp collisions using 20 fb$^{-1}$ of ATLAS data

A search is presented for direct top squark pair production in final states with two leptons (electrons or muons) of opposite charge using 20.3~fb$^{-1}$ of $pp$ collision data at $\sqrt{s}=8$ TeV, collected by the ATLAS experiment at the Large Hadron Collider in 2012. No excesses over Standard Model expectations are observed, and the results are interpreted under the separate assumptions that the lightest top squark decays to a $b$-quark and the lightest chargino, or to a $t$-quark and the lightest neutralino.