Observability of same-charge lepton topology in di-leptonic ttbar events

At the Large Hadron Collider di-leptonic ttbar(+jets) events can be selected with a relatively high signal-to-noise ratio and efficiency, where the background events are produced via Standard Model diagrams. Within the clean sample of these events, both leptons have an opposite electric charge. In several models beyond the Standard Model however, tt(+jets) topologies which are kinematically similar to the Standard Model ttbar(+jets) event topology, are predicted where both leptons have an equal electric charge. The signal of new physics can be diluted by the mis-identification of the electric charge of the leptons in Standard Model ttbar(+jets) events. This paper discusses the bservability of the excess of same-sign signals above the mis-reconstruction of the Standard Model background. With an integrated luminosity of 30fb-1, the same-sign signature of pp -> tt events with a cross-section larger than 1pb is visible in the measurement of the ratio between same-sign and different charged leptons pair events.