In the case of the signal process , top quarks are produced more abundantly relative to their antiquark partners due to the charge asymmetry of the W boson radiated from the initial - state quark in pp collisions at the LHC . This leads to a higher relative background contamination in the l − final state arising from top antiquark decay compared to the l + final state from top quark decay , as shown in Fig . 7 . As a result , the measurement in the l − final state is more sensitive to the sources that significantly alter the background contributions along with the signal , compared to the ones that impact the signal contribution only . This is reflected in Table 3 where the uncertainties from the signal modeling are lower for the l − case ; whereas other sources , except for the ones listed under flavor - dependent JES , that alter the background contributions along with the signal have a larger impact on the total uncertainty . In the case of the flavor - dependent Table 3 : Summary of the m t uncertainties in GeV for each final - state lepton charge configuration . The statistical uncertainties are obtained by performing the fits again in each case while fixing the nuisance parameters to their estimated values from data . With the exception of the flavor - dependent JES sources , the total systematic uncertainty is obtained from the quadrature sum of the individual systematic sources . The amount of statistical fluctuations in the systematic shifts are quoted within parentheses whenever alternative simulated samples with systematic variations have been used . These are determined from 1000 pseudo - experiments in each case . Entries with < 0.01 denote that the magnitude of the systematic bias is less than 0.01 .