UC San Diego

A search for Z boson production with associated top- antitop pairs is performed with a final state which contains trileptons and b-tagged jets. The measurement is performed on the complete dataset of pp collisions at a center-of-mass energy of 8 TeV collected at the CMS detector, for a total instantaneous luminosity of 19.5 fb⁻¹. A cross section is calculated for this final state and compared to the standard model prediction. The cross section for tt̄Z production is measured to be sigma=194⁺¹⁰⁵ /₋₈₉ fb. The measured cross section to theoretical cross section ratio is 0.94⁺⁰̇̇̇·⁵¹/₋₄₃. The process is measured with a significance of 2.33. This measurement is then combined with an outside 4 lepton channel measurement for an equivalent cross section measurement of sigma=200⁺⁹⁰/₋₇₆ fb and a significance of 3.1