# alphas-2019: Workshop on precision measurements of the QCD coupling constant

ALPHAS2019
11-15 February 2019
ECT*, Villazzano Trento
published September 13, 2019

The strong coupling constant alpha_S is the least well known of all constants of nature, which play a role in the Standard Model (SM) of
particle physics and related fields such as cosmology and astrophysics. For many searches for new physics beyond the SM as well as for some important precision tests of the SM using collider data the uncertainty on the value of ?? is a limiting factor. In recent years progress in theoretical predictions of Quantum Chromodynamics (QCD), and the availability of collider data at the highest energies has led to many improved determinations of alpha_S. The current world average quotes an uncertainty of less than 1%. However, there are noticeable discrepancies between different categories of
determinations of alpha_S, which may limit the ultimate precision of future world averages. We plan to bring together in this workshop the
leading experts on determinations of alpha_S from theory and experiment and all important categories. With presentations of the latest results and intense discussion by all participants we will focus on a global view of advantages and problems of each method.

### Editorial Board

• David d’Enterria
CERN
• Stefan Kluth
Max-Planck-Institut fur Physik (DE)
Sessions
Overview and Introduction
$a_S$ from $e^+e^-$ hadronic and tau pair final states
$a_S$ from electroweak observables
$a_S$ at hadron colliders
$a_S$ from DIS & PDFs
$a_S$ from tau decays
$a_S$: Lattice OCD
Conclusion
 Overview and Introduction Pre-2019 summaries of $α_s$ PoS(ALPHAS2019)001 S. Bethke $a_S$ from $e^+e^-$ hadronic and tau pair final states Old and new observables for $α_S$ from $e^+e^-$ to hadrons PoS(ALPHAS2019)002 G. Somogyi, A. Kardos, S. Kluth, Z. Trocsanyi, Z. Tulipant and A. Verbytskyi $a_S$ from energy-energy correlations and jet rates in $e^+e^-$ collisions PoS(ALPHAS2019)003 A. Verbytskyi, A. Banfi, A. Kardos, S. Kluth, P.F. Monni, G. Somogyi, Z. Szőr, Z. Trocsanyi, Z. Tulipant and G. Zanderighi The strong coupling from $e^+e^-$ to hadrons PoS(ALPHAS2019)004 M. Golterman, D. Boito, A. Keshavarzi, K. Maltman, D. Nomura, S. Peris and T. Teubner $a_S$ from soft QCD jet fragmentation functions PoS(ALPHAS2019)005 R. Pérez Ramos and D. d’Enterria $a_S$ from electroweak observables The QCD coupling $αs$ (Q2)at all momentum scales and the elimination of renormalization scale uncertainties PoS(ALPHAS2019)006 S.J. Brodsky Higgs-boson, tau-lepton, and Z-boson decay ratesin fourth order and the five-loop $β$ function of QCD PoS(ALPHAS2019)007 J. Kühn, P. Baikov and K. Chetyrkin High-precision $α_S$ from W and Z hadronic decays PoS(ALPHAS2019)008 D. d’Enterria $a_S$ at hadron colliders $α_s$ from jets in $pp$ collisions PoS(ALPHAS2019)009 J.R. Pires Jet substructure and a possible determination of the QCD coupling PoS(ALPHAS2019)010 F. Ringer Extractions of the QCD coupling in ATLAS PoS(ALPHAS2019)011 F. Barreiro Alonso and  on behalf of the ATLAS Collaboration $a_S$ determinations from CMS PoS(ALPHAS2019)012 K. Rabbertz and  on behalf of the CMS Collaboration $a_S$ extraction from inclusive W and Z cross sections in pp collisions at the LHC PoS(ALPHAS2019)013 A. Poldaru, D. d’Enterria and X. Weichen Determination of $a_S(m_Z)$ from the Z-boson transverse momentum distribution PoS(ALPHAS2019)014 S. Camarda $a_S$ from DIS & PDFs $a_S$ from pdfs PoS(ALPHAS2019)015 J.W. Huston $a_S$, ABM PDFs, and heavy-quark masses PoS(ALPHAS2019)016 S. Alekhin, J. Blümlein and S.O. Moch $a_S$ from H1 jets PoS(ALPHAS2019)017 D. Britzger and  on behalf of the H1 and NNLOJET Collaboration $a_S$ from tau decays $a_S$ from non-strange hadronic tau decays PoS(ALPHAS2019)018 S. Peris, D. Boito, M. Golterman and K. Maltman QCD coupling: scheme variations and tau decays PoS(ALPHAS2019)019 R. Miravitllas and M. Jamin $a_S$: Lattice OCD The 2019 lattice FLAG $a_S$ average PoS(ALPHAS2019)020 R. Sommer, T. Onogi and R. Horsley Strong coupling constant from moments of quarkonium correlators PoS(ALPHAS2019)021 P. Petreczky $a_S$ from the ALPHA collaboration (part I) PoS(ALPHAS2019)022 S. Sint $a_S$ from the ALPHA collaboration (part II) PoS(ALPHAS2019)023 M. Dalla Brida $a_S$ from the QCD static energy PoS(ALPHAS2019)024 N. Brambilla, A. Bazavov, X. Garcia i Tormo, P. Petreczky, J. Soto, A. Vairo and J.H. Weber $a_S$ determination from static QCD potential with renormalon subtraction PoS(ALPHAS2019)025 H. Takaura Conclusion $\alpha_s$(2019) discussions summary PoS(ALPHAS2019)026 D. d’Enterria, S. Alekhin, F. Barreiro Alonso, S. Bethke, N. Brambilla, D. Britzger, S.J. Brodsky, S. Camarda, M. Dalla Brida, M. Golterman, J.W. Huston, S. Kluth, J. Kühn, R. Miravitllas, R. Pérez Ramos, S. Peris, P. Petreczky, J.R. Pires, A. Poldaru, K. Rabbertz, F. Ringer, S. Sint, R. Sommer, G. Somogyi, H. Takaura and A. Verbytskyi