Estimation of non-prompt and fake lepton backgrounds in final states with top quarks produced in proton-proton collisions at \sqrt{s}=8~TeV with the ATLAS detector

This note presents methods for estimating non-prompt and fake lepton backgrounds developed in the context of top analyses using the ATLAS detector. The analysis is performed on the ATLAS 2012 proton-proton collision data sample, collected at the LHC, corresponding to a luminosity of 20.3 fb-1 at sqrt(s)=8 TeV. Final states with lepton+jets and dilepton events are considered. Two different data-driven methods are described and compared. The first method (matrix method) is based on the measurement of efficiencies of leptons with relaxed identification criteria. The second one (fitting method) is based on the construction of templates for non-prompt and fake leptons. For final states with two leptons, the systematic uncertainties of the estimates using the matrix method are 30-100%. For final states with one lepton, the two methods give consistent results within systematic uncertainties, which are 10-50% for the matrix method and 50% for the fitting method.