Precision measurement of the Z invisible width with the CMS experiment in pp collisions at $\sqrt{s}=13~\mathrm{TeV}$

A direct measurement of the invisible width of the Z boson in proton-proton collisions at a center-of-mass energy of $13~\mathrm{TeV}$ is presented using data recorded by the CMS experiment at the LHC corresponding to an integrated luminosity of $36.3~\mathrm{fb}^{-1}$. The result is extracted from a simultaneous fit to data regions containing predominantly Z boson decay to invisible particles and those dominated by Z boson decay to electron and muon pairs. The invisible width is measured to be $523\pm 3\mathrm{(stat)}\pm 16\mathrm{(syst)~\mathrm{MeV}}$. This result is the first measurement of the Z invisible width at a hadron collider and is the single most precise direct measurement in the world, competitive with the combined direct measurement from the LEP experiments.