The LHC, being a “top quark factory”, can very efficiently assist in precise measurement of various properties of the top quark. We carefully study a particular observable, namely, the invariant mass of the b-jet and the lepton (mbℓ) assuming leptonic decay of the W ± boson arising from pair produced top quarks. Our goal is to check if there exist a BSM particle with mass around mt, can it cause any deviation in the mbℓ distribution. This method applies to any BSM theory that can accommodate an exotic particle with mass around mt and can give rise to a final state similar to fully leptonic decay of pair produced top-quarks. Here, as an example, we consider the Minimal Supersymmetric Standard Model (MSSM) with the mass of the lightest stop around the mass of the top quark. We evaluate the light top squark pair production followed by decays such that the final state is a pair of b−jets + a pair of opposite sign leptons + /ET and hence calculate and compare mbℓ obtained from MSSM signal against that obtained from top pair production. We observe some excess due to this signal in the mbℓ distribution after the acceptance cuts at √s = 13 TeV.