Precision Measurements of Electroweak Parameters – PMEP

The discovery of the Higgs boson during the LHC Run 1 completes the experimental validation of the Standard Model (SM) of high-energy particle physics. Its particle spectrum is fully established, and definite predictions are available for all interactions. At the quantum level, the SM relates the masses of the heaviest particles the W and Z gauge bosons, the Higgs boson, and the top quark. The Z boson mass is precisely known since LEP1, and the measurement precision of the top quark mass has vastly improved at the TeVatron and LHC. In 2014, the ATLAS and CMS collaborations produced a precise measurement of the Higgs boson mass, based on the full 7 and 8 TeV datasets; in 2016, ATLAS completed a first measurement of mW, using 7 TeV data only, that matches the precision of the best previous results. The present proposal aims at further improvement in the measurements of mW, mZ and the weak mixing angle with ATLAS, exploiting all data available at 8 and 13 TeV. Leptonic final states
play a particular role, and improving the measurement of electrons and muons is our main focus on the experimental side. A set of dedicated measurements is foreseen to bring our understanding of strong interaction effects to the required level. Finally, a global analysis of the electroweak parameters is proposed, accounting for correlations of QCD uncertainties across the different measurements, extending traditional electroweak fits. The involved scientists and institutes have recognized expertise and achievements in the fields spanned by this project. The present call provides a unique opportunity to strengthen our collaboration over a timescale matching the needs of our ambition.