Abstract

For a long time, global fits of the electroweak sector of the Standard Model (SM) have been used to exploit measurements of electroweak precision observables at lepton colliders (LEP, SLC), together with measurements at hadron colliders (Tevatron, LHC), and accurate theoretical predictions at multi-loop level, to constrain the free parameters of the SM, like the Higgs and top masses.   Today, all fundamental SM parameters, including information on the  Higgs couplings, are experimentally determined and the global fits  are used as powerful tools to assess the validity of the theory and  to constrain scenarios for new physics. Future measurements at the  Large Hadron Collider (LHC) and the International Linear Collider (ILC)  promise to improve the experimental precision of key observables used  in the fit. After an update of the current electroweak fit results based on latest 2-loop calculations, we present the prospects for the LHC and ILC. We perform a  detailed analysis of the impact of present and future sources of systematic  uncertainties on the fit predictions. By using LHC measurements of the signal  strength of Higgs production and decay channels we examine the present and future  impact of electroweak precision observables on a model with modified  couplings of the Higgs boson to fermions and bosons.