OBSERVABILITY OF SAME-CHARGE LEPTON TOPOLOGIES IN FULLY LEPTONIC TOP QUARK PAIR EVENTS IN CMS

摘要

At the Large Hadron Collider dileptonic tt(+jets) events can be selected with a relatively high signal-to-noise ratio and efficiency, with background events produced via Standard Model diagrams. Within the clean sample of these events, both isolated leptons have an opposite electric charge. In several models beyond the Standard Model tt/tt(+jets) topologies are predicted, kinematically similar to the Standard Model tt(+jets) signature, where both leptons have an equal electric charge. Such a signal of new physics can be diluted by the mis-identification of the leptons or their electric charge in Standard Model tt(+jets) events. The observability of an excess of same-charge dilepton signals above the mis-reconstruction of the Standard Model background is presented, assuming the same topology. With an integrated luminosity of 30 fb~(-1), a same-charge dilepton signature of pp → tt/tt events with a cross section larger than 1.2 pb is visible in the measurement of the ratio between same-charge and opposite-charge lepton pair events [J. D'Hondt, S. Lowette, G. Hammad, J. Heyninck, P. Van Mulders, "Observability of same-charge lepton topology in dileptonic events tt", CERN-CMS-NOTE-2006-065.].