The global electroweak fit at NNLO and prospects for the LHC and ILC

TL;DR

This paper updates the global electroweak fit using NNLO predictions, analyzes uncertainties, and explores future constraints on Higgs couplings from the LHC and ILC, enhancing tests of the Standard Model and new physics scenarios.

Contribution

It provides the latest NNLO-based electroweak fit results and assesses future experimental prospects at the LHC and ILC for constraining Higgs couplings.

Findings

Updated electroweak fit results with NNLO predictions

Detailed analysis of experimental and theoretical uncertainties

Comparison of indirect fit constraints with direct LHC measurements

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 free parameters of the SM, such as the Higgs and top masses. Today, all fundamental SM parameters entering these fits are experimentally determined, including information on the Higgs couplings, 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 fits. This paper presents updated electroweak fit results using newest NNLO theoretical predictions, and prospects for the LHC and ILC. The impact of experimental and theoretical uncertainties is analysed in detail. We compare constraints from the electroweak fit on the Higgs couplings with direct LHC measurements, and examine present and future prospects of these constraints using a model with modified couplings of the Higgs boson to fermions and bosons.