electrons and muons must have pseudorapidity $|\eta|<2.5$ and $|\eta|<2.4$, respectively. In addition, each lepton must satisfy an isolation requirement computed using the $\pt$ sum of all stable particles within $\Delta R<0.4$ distance from that lepton. The $\pt$ sum excludes any neutrinos, as well as any photon or stable lepton that is a daughter of the lepton for which the isolation sum is being computed. The ratio of this sum and the $\pt$ of the considered lepton must be less than $0.4$, in line with the requirement on the lepton isolation at the reconstruction level [@Chatrchyan:2013mxa]. The inclusion of isolation is an important step in the fiducial phase space definition as it reduces significantly the differences in signal selection efficiency between different signal models. It has been verified in simulation that the signal selection efficiency differs by up to 45% between different models if the lepton isolation requirement is not included. This is especially pronounced in case of large associated jet activity as in the case of ${\ensuremath{\PQt \PAQt \PH}\xspace}$ production mode. Exclusion of neutrinos and FSR photons from the computation of the isolation sum brings the definition of the fiducial phase space closer to the reconstruction level, and improves the 