alpha_S(2022): Workshop on precision measurements of the strong coupling constant

31 January 2022 — 04 February 2022

The strong coupling constant alpha_S is the leading parameter of the theory of the strong interaction (Quantum chromodynamics, QCD), it is the least well-known of all interaction constants of nature, and it plays a key role in the Standard Model (SM) of particle physics with a direct impact on all cross sections and decays involving strongly-interacting particles. For many searches for new physics beyond the SM, as well as for important precision tests of the SM using collider data, the uncertainty on the value of alpha_S is today a limiting factor. In recent years, progress in theoretical perturbative QCD predictions at next-to-next-to-leading order accuracy and beyond, and the availability of precision collider data at the highest energies has led to updated determinations of alpha_S. The current world average quotes an uncertainty of around 1%. However, there are still discrepancies between different categories of determinations of alpha_S, which may limit the ultimate precision of future alpha_S world averages. We plan to bring together in this workshop the leading experts on the extraction of alpha_S from theory and experiment to discuss current and newly proposed observables. The presentations of the latest results, followed by intense discussions among participants, will provide a global view of the advantages and problems of each method, and of the ultimate precision achievable on the determination of alpha_S.

The workshop aims at exploring in-depth the current status and upcoming prospects in the determination of the QCD coupling constant alpha_S(m_Z) from the key observables where high precision measurements and theoretical calculations are (or will be) available: lattice QCD, hadronic decays of tau leptons, deep-inelastic electron-proton scattering and global parton density analyses, QCD corrections to electroweak precision observables, and analysis of hadronic final states in high energy particle collisions (e+e-, ep, and pp).


  • David d'Enterria (CERN/CH)
  • Stefan Kluth (Max-Planck-Institute for Physics / Werner-Heisenberg-Institute (MPP))
  • Giulia Zanderighi (Max-Planck-Institute for Physics)
See complete details and information

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