The measurements of the inclusive and differential fiducial cross sections of
the Higgs boson decaying to a pair of photons are presented. The analysis is performed
using proton-proton collisions data recorded with the CMS detector at the LHC at a
centre-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 137 fb−1.
The inclusive fiducial cross section is measured to be σfid = 73.4+5.4
−5.3(stat)+2.4
−2.2(syst) fb, in
agreement with the standard model expectation of 75.4 ± 4.1 fb. The measurements are
also performed in fiducial regions targeting different production modes and as function of
several observables describing the diphoton system, the number of additional jets present
in the event, and other kinematic observables. Two double differential measurements are
performed. No significant deviations from the standard model expectations are observed.