We present results by the ALPHA collaboration for the Λ-parameter in
3-flavour QCD and the strong coupling constant at the electroweak scale,
αs​(mZ​), in terms of hadronic quantities computed on the CLS gauge
configurations. The first part of this proceedings contribution contains a
review of published material \cite{Brida:2016flw,DallaBrida:2016kgh} and yields
the Λ-parameter in units of a low energy scale, 1/Lhad​. We
then discuss how to determine this scale in physical units from experimental
data for the pion and kaon decay constants. We obtain ΛMS(3)​=332(14) MeV which translates to αs​(MZ​)=0.1179(10)(2)
using perturbation theory to match between 3-, 4- and 5-flavour QCD.Comment: 21 pages. Collects contributions of A. Ramos, S. Sint and R. Sommer
to the 34th annual International Symposium on Lattice Field Theory; LaTeX
input encoding problem fixe