Measurement of the Higgs boson mass with $H \rightarrow γγ$ decays in 140 fb$^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

The mass of the Higgs boson is measured in the $H\to\gamma\gamma$ decaychannel, exploiting the high resolution of the invariant mass of photon pairsreconstructed from the decays of Higgs bosons produced in proton-protoncollisions at a centre-of-mass energy $\sqrt{s}=13$ TeV. The dataset wascollected between 2015 and 2018 by the ATLAS detector at the Large HadronCollider, and corresponds to an integrated luminosity of 140 fb$^{-1}$. Themeasured value of the Higgs boson mass is $125.17 \pm 0.11 \mathrm{(stat.)} \pm0.09 \mathrm{(syst.)}$ GeV and is based on an improved energy scale calibrationfor photons, whose impact on the measurement is about four times smaller thanin the previous publication. A combination with the corresponding measurementusing 7 and 8 TeV $pp$ collision ATLAS data results in a Higgs boson massmeasurement of $125.22 \pm 0.11 \mathrm{(stat.)} \pm 0.09 \mathrm{(syst.)}$GeV. With an uncertainty of 1.1 per mille, this is currently the most precisemeasurement of the mass of the Higgs boson from a single decay channel.