level the requirement on the output of the photon identification classifier applied on reconstructed quantities, as described in Section \[sec:selection\]. Further requirements, that depend on the observable under study, can be applied on top of this “baseline” phase space definition. For observables involving only one jet, events with at least one jet with $\abs{\eta^j}<2.5$, selected as described in Section \[sec:selection\], are retained, corresponding to $\sim$35% of the signal events in the baseline phase space. Observables involving two jets are studied by requiring at least two jets with $\abs{\eta^j}<4.7$ and defined as in Section \[sec:selection\], further restricting the region of the phase space to $\sim$16% of the baseline selection. A VBF-enriched region of the fiducial phase space, where a subset of the two-jet observables is measured, is defined by requiring the presence of two reconstructed and selected jets within $\abs{\eta^j}<4.7$, with a combined invariant mass ${\ensuremath{m^{{\ensuremath{j_{\text{1}}}}{\ensuremath{j_{\text{2}}}}}}\xspace}$ greater than $200$and a pseudorapidity gap between the jets ${\ensuremath{\abs{\Delta\eta^{{\ensuremath{j_{\text{1}}}},{\ensuremath{j_{\text{2}}}}}}}\xspace}$ greater than $3.5$, exploiting the main kinematic features of the VBF production mode. This set of criteria selects $\sim$3.8% of the signal events contained in the baseline phase space. The definition of the four regions of the fiducial phase space is summarized in Table \[tab:observables\], 