Wing Sheung Chan

112 Statistical interpretation and results Table 6.1.: A summary of the postfit uncertainties and their impacts on the measured signal branching fraction. The statistical uncertainties include those in the determination of the total yields from fakes and Z → ττ or Z → `τ decays. The uncertainties in the Z -boson modelling include those in the correction of the simulated transverse momentum and the measured production cross section of the Z boson. Uncertainty Impact on the signal branching fraction [ 10 − 6 ] eτ µτ Statistical ± 3.5 ± 2.8 Systematic ± 2.3 ± 1.6 Tau ± 1.9 ± 1.5 Energy calibration ± 1.3 ± 1.4 Jet rejection ± 0.3 ± 0.3 Electron rejection ± 1.3 Light leptons ± 0.4 ± 0.1 E miss T , jets and flavour tagging ± 0.6 ± 0.5 Z -boson modelling ± 0.7 ± 0.3 Luminosity and other minor backgrounds ± 0.8 ± 0.3 Total ± 4.1 ± 3.2 Table 6.2.: Best-fit values and uncertainties of B ( Z → `τ ) and the background normalisation factors. The uncertainties include both the statistical and systematic contributions. eτ µτ B ( Z → `τ ) [ 10 − 6 ] − 0 . 1 ± 4 . 1 4 . 3 ± 3 . 3 µ Z 1 . 02 ± 0 . 02 0 . 97 ± 0 . 02 µ 1P fakes 0 . 98 ± 0 . 02 1 . 00 ± 0 . 02 µ 3P fakes 1 . 03 ± 0 . 04 1 . 14 ± 0 . 04