The 4th China LHC Physics Workshop (CLHCP 2018)

A search for new physics in top quark production is performed in proton-proton collisions at 13 TeV. The data set corresponds to an integrated luminosity of 35.9 fb^-1, and was collected in 2016 by the CMS detector. Events with two opposite-sign isolated leptons (electrons or muons) and b quark jets in the final state are selected. The search is sensitive to new physics in top quark pair production and in single top quark production in association with a W boson. This is the first search for new physics that uses the tW process. No significant deviation from the standard model expectation is observed. Results are interpreted in the framework of an effective field theory and constraints on the relevant effective couplings are set using a dedicated multivariate analysis.