Measurement of fiducial, differential and production cross sections in the $H\to\gamma\gamma$ decay channel with 13.3 fb$^{-1}$ of 13 TeV proton-proton collision data with the ATLAS detector

This note presents preliminary measurements of the Higgs boson properties measured in the $H\to\gamma\gamma$ decay channel using 13.3 fb$^{-1}$ of proton-proton collision data taken at $\sqrt{s}=$ 13 TeV by the ATLAS experiment at the LHC. Fiducial and differential cross section measurements are presented in a variety of phase space regions and as a function of several kinematic variables. The fiducial cross section is measured to be $ \sigma_{\rm fid} = 43.2 \pm 14.9\, ({\rm stat.}) \pm 4.9 \, ({\rm syst.})\,\mathrm{fb}$ for a Higgs boson of mass 125.09 GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity $|\eta|<2.37$, excluding the region $1.37 < |\eta|<1.52$. The Standard Model prediction for the same fiducial region is $62.8 \, ^{+3.4}_{-4.4}\,$fb. Finally, production cross section measurements for a Higgs boson rapidity $|y_H|<$ 2.5 and in the full phase space are presented for gluon fusion, vector boson fusion, and Higgs boson production in association with a vector boson or a top-antitop pair. In addition, the signal strength, defined as the ratio of the observed signal yield to the expected signal yield, is measured for the same production processes as well as globally. No significant deviation from the Standard Model expectations is observed.