\to 4\ell}\xspace}$ and ${\ensuremath{\PZ \to 4\ell}\xspace}$ measurements ($50 < m_{4\ell} < 140\GeV$) are shown in Fig. \[fig:mass4l\_PAS\] for the 7 and 8data sets, and compared to the SM expectations.

![Distributions of the $m_{4\ell}$ observable in 7(left) and 8(right) data, as well as expectations for the SM Higgs boson ($m_{\PH}=125.0\GeV$) and other contributing SM processes, including resonant ${\ensuremath{\PZ \to 4\ell}\xspace}$ decays.[]{data-label="fig:mass4l_PAS"}](plots/Mass4l_DataMC_7TeV_mH125GeV_fullRange.pdf "fig:"){width="48.00000%"} ![Distributions of the $m_{4\ell}$ observable in 7(left) and 8(right) data, as well as expectations for the SM Higgs boson ($m_{\PH}=125.0\GeV$) and other contributing SM processes, including resonant ${\ensuremath{\PZ \to 4\ell}\xspace}$ decays.[]{data-label="fig:mass4l_PAS"}](plots/Mass4l_DataMC_8TeV_mH125GeV_fullRange.pdf "fig:"){width="48.00000%"}

Fiducial phase space definition {#sec:Fiducial}
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The acceptance and selection efficiency for the ${\ensuremath{\PH \to 4\ell}\xspace}$ decays can vary significantly between different Higgs boson production mechanisms and different exotic models of Higgs boson properties. In processes with large jet activity (such as the ${\ensuremath{\PQt \PAQt \PH}\xspace}$ production), or with low invariant mass of the second lepton pair (such as $\PH \to  \PZ\gamma^{*}(\gamma^{*}\gamma^{*})  \to 4 \ell$ processes), or with the ${\ensuremath{\PH \to 4\ell}\xspace}$ kinematics different from the SM estimation (such as exotic Higgs-like spin-one models), the inclusive acceptance of signal events can differ by up to 70% from the inclusive acceptance estimated for SM ${\ensuremath{\PH \to 4\ell}\xspace}$ decays.

