Searching for pair production of top squarks in $\sqrt s$ = 7 TeV and $\sqrt s$ = 8 TeV proton-proton collisions and final state swith two leptons at the ATLAS experiment

The search for Supersymmetric extensions of the Standard Model (SUSY) remains a hot topic in high energy physycs in the light of the discovery of the Higgs boson with mass of 125 GeV. Supersymmetric particles can cancel out the quadratically-divergent loop corrections to the Higgs boson mass and can explain presence of Dark Matter in the Universe. Moreover, SUSY can unify the gauge couplings of the Standard Model at high energy scales. Under certain theoretical assumptions, the supersymmetric partner of the top quark, i.e. the top squark, is preferred to be lighter than one TeV and its discovery can thus be accessible at the LHC.