output of photon identification classifier. Events with ${\ensuremath{\sigma_{m}^{D}}\xspace}>0.030$ are discarded (shaded gray region in Fig. \[fig:sigmaMoverM\]). The efficiency of the photon identification selection is roughly 80% for signal events in the fiducial phase space, discussed in Section \[sec:observables\]. The categories obtained from the optimization process correspond approximately to the configurations where both photons are reconstructed in the central barrel ($\abs{\eta}<1$) for the first category, both photons are reconstructed in the barrel with at least one falling outside the central barrel for the second category, and at least one photon reconstructed in the endcap regions of the ECAL for the last category.

Observables and fiducial phase space {#sec:observables}
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The analysis provides measurements of the production cross section of the Higgs boson in a fiducial phase space. This is defined by a set of selection criteria at generator level based on kinematic, geometrical and isolation variables, as well as on the topology of the event. By defining a fiducial phase space, the measurements are compared to the theoretical predictions while avoiding the extrapolation to the full phase space and the consequent uncertainty. In order to extend such a comparison to future and alternative theoretical calculations, it is important to have a 