Search for new physics in the lepton plus missing transverse momentum final state in proton-proton collisions at 13 TeV center-of-mass energy

A search for physics beyond the standard model in final states with an electron, or muon, and missing transverse momentum is presented. The analysis uses data from proton-proton collisions at 13 TeV center-of-mass energy, collected with the CMS detector at the LHC in 2016, 2017, and 2018 corresponding to a total integrated luminosity of $137~\mathrm{fb}^{-1}$. No significant deviation from the standard model prediction is observed. Model-independent limits are set on the production cross section of $W'$ bosons decaying into lepton plus neutrino final states. This analysis also sets limits on the parameters of other new physics models. The best exclusion limit obtained is 5.7 TeV at $95\%$ confidence level on the mass of a sequential standard model $W'$ boson with standard-model-like couplings and comes from combining electron and muon decay channels. Results on oblique electroweak parameters, in particular on the $W$ parameter, are also presented, for the first time using LHC data.