The strong coupling constant: State of the art and the decade ahead
D. d'Enterria, S. Kluth, G. Zanderighi, C. Ayala, M. A. Benitez-Rathgeb, J. Bluemlein, D. Boito, N. Brambilla, D. Britzger, S. Camarda, A. M. Cooper-Sarkar, T. Cridge, G. Cvetic, M. Dalla Brida, A. Deur, F. Giuli, M. Golterman, A. H. Hoang, J. Huston, M. Jamin, A. V. Kotikov, V. G. Krivokhizhin, A. S. Kronfeld, V. Leino, K. Lipka, T. Makela, B. Malaescu, K. Maltman, S. Marzani, V. Mateu, S. Moch, P. F. Monni, P. Nadolsky, P. Nason, A. V. Nesterenko, R. Perez-Ramos, S. Peris, P. Petreczky, A. Pich, K. Rabbertz, A. Ramos, D. Reichelt, A. Rodriguez-Sanchez, J. Rojo, M. Saragnese, L. Sawyer, M. Schott, S. Schumann, B. G. Shaikhatdenov, S. Sint, G. Soyez, D. Teca, A. Vairo, M. Vos, C. Waits, J. H. Weber, M. Wobisch, K. Xie
This document provides a comprehensive summary of the state-of-the-art, challenges, and prospects in the experimental and theoretical study of the strong coupling . The current status of the seven methods presently used to determine based on: (i) lattice QCD, (ii) hadronic decays, (iii) deep-inelastic scattering and parton distribution functions fits, (iv) electroweak boson decays, hadronic final-states in (v) e+e-, (vi) e-p, and (vii) p-p collisions, and (viii) quarkonia decays and masses, are reviewed. Novel determinations are discussed, as well as the averaging method used to obtain the PDG world-average value at the reference Z boson mass scale, . Each of the extraction methods proposed provides a "wish list" of experimental and theoretical developments required in order to achieve an ideal permille precision on within the next 10 years.