Searches for Supersymmetry with multiple b-jets with the ATLAS detector

This thesis presents two searches for supersymmetry using proton-proton collision data collected with the ATLAS detector from 2015 to 2018 corresponding to the Run 2 dataset with a total integrated luminosity of $139\mathrm{fb}^{-1}$ at $\sqrt{s}=13$ TeV. The calibration of the DL1r algorithm responsible for the identification of jets originating from $b$-hadrons (\bjets) for jets reconstructed using the ParticleFlow algorithm and the \RunTwo dataset, is also presented. The first search targets the supersymmetric signature of pair-produced gluinos decaying to top-anti-top or bottom-anti-bottom pairs and the lightest neutralino. The resulting detector signature is expected to contain multiple \bjets\xspace and large amounts of missing transverse energy. The second search presents a model-independent strategy that utilises a Gaussian function to search for excesses above the Standard Model (SM) in a observable sensitive to beyond the SM (BSM) events. No significant excesses above the SM prediction were observed from either search. Subsequently, 95% confidence limits (CL) were set in the gluino-neutralino mass plane and for the cross section of a signal distributed according to Gaussian function, respectively. Additionally, model-independent limits on the number of BSM events at 95% CL have also been set.