Measurement of the Z Boson Invisible Width at √s=13 Tev With the Atlas Detector

Abstract

A measurement of the invisible width of the boson using events with jets and missing transverse momentum is presented using 37 fb(-1) of 13 TeV proton-proton data collected by the ATLAS detector in 2015 and 2016. The ratio of Z -> inv to Z -> ll events, where inv refers to non-detected particles and l is either an electron or a muon, is measured and corrected for detector effects. Events with at least one energetic central jet with p(T) >= 110 GeV are selected for both the Z -> inv and Z -> ll final states to obtain a similar phase space in the ratio. The invisible width is measured to be 506 +/- 2 (stat.) +/- 12 (syst.) MeV 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.