Measurement of Higgs boson decay to a pair of muons in proton-proton collisions at $\sqrt{s}=13\,\mathrm{TeV}$

A measurement of the Higgs boson decay to a pair of muons is presented. This result combines searches in four exclusive categories targeting the production of the Higgs boson via gluon fusion, via vector boson fusion, in association with a weak vector boson, and in association with a pair of top quarks. The measurement is performed using ${\sqrt{s}=13\,\mathrm{TeV}}$ proton-proton (pp) collision data, corresponding to an integrated luminosity of ${137\,\mathrm{fb}^{-1}}$, recorded by the CMS experiment at the CERN LHC. An excess of events is observed in data with a significance of 3.0 standard deviations, where the expectation for the standard model (SM) Higgs boson with ${m_{\mathrm{H}} = 125.38\,\mathrm{GeV}}$ is 2.5. The measured signal strength, relative to the SM expectation, is ${1.19^{+0.41}_{-0.39}(\mathrm{stat})^{+0.17}_{-0.16}(\mathrm{sys})}$. The combination of this result with that from data recorded at centre-of-mass energies of 7 and ${8\,\mathrm{TeV}}$ improves both expected and observed sensitivity by $1\%$. This result constitutes the first evidence for the Higgs boson decay to fermions of the second generation.