Measurement of the Higgs boson total decay width using the H $\to$ WW $\to$ e$\nu \mu \nu$ decay channel in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The Higgs boson (H) decay width is determined from the ratio of off- and on-shell production of H $\to$ WW $\to$ e$\nu \mu \nu$ using proton-proton collision data corresponding to an integrated luminosity of 138 fb${}^{-1}$ collected at $\sqrt{s}$ = 13 TeV by the CMS experiment at the Large Hadron Collider. The off-shell signal strength is measured as ${\mu }_{\text{off-shell}}$ = 1.2 ${}_{-0.7}^{+0.8}$. The Higgs boson total decay width is ${\mathrm{\Gamma }}_{\text{H}}$ = 3.9 ${}_{-2.2}^{+2.7}$ MeV, in agreement with the standard model prediction. The uncertainty in this result represents a factor of three improvement over the previous CMS result in this decay channel.