Measurement of the Z boson invisible width at $\sqrt{s}=13$ TeV with the ATLAS detector

A measurement of the invisible width of the \ZBoson\ using events with jets and missing transverse momentum, \MET, is presented using 37 \ifb of 13 \TeV\ proton-proton data collected by the ATLAS detector in 2015 and 2016. To obtain this result, the ratio of \Zinv to \Zll events is measured and corrected for all detector effects. Events with at least one energetic central jet with $\pT \geq 110~\GeV$ are selected for both \Zinv and \Zll final states in order to obtain a similar phase space between the numerator and the denominator of the ratio. The invisible width is measured to be \ZinvValue and is the single most precise recoil-based measurement. The result is in agreement with the most precise determination from LEP and the Standard Model prediction based on three neutrino generations.