We review the ALPHA collaboration strategy for obtaining the QCD coupling at high scale. In the three-flavor effective theory it avoids the use of perturbation theory at α∼ >0.2 and at the same time has the physical scales small compared to the cutoff 1/a in all stages of the computation. The result ΛMS‾ (3)=332(14)MeV is translated to αMS‾(mZ)=0.1179(10)(2) by use of (high order) perturbative relations between the effective theory couplings at the charm and beauty quark “thresholds”. The error of this perturbative step is discussed and estimated as 0.0002
Bruno, M., Dalla Brida, M., Fritzsch, P., Korzec, T., Ramos, A., Schaefer, S., et al. (2017). The determination of αs by the ALPHA collaboration. Intervento presentato a: 6th Workshop on Theory, Phenomenology and Experiments in Flavour Physics : Interplay of Flavour Physics with electroweak symmetry breaking. (Capri 2016), Anacapri, Capri, Italy [10.1016/j.nuclphysbps.2017.03.024].
The determination of αs by the ALPHA collaboration
Bruno, M;Dalla Brida, M;
2017
Abstract
We review the ALPHA collaboration strategy for obtaining the QCD coupling at high scale. In the three-flavor effective theory it avoids the use of perturbation theory at α∼ >0.2 and at the same time has the physical scales small compared to the cutoff 1/a in all stages of the computation. The result ΛMS‾ (3)=332(14)MeV is translated to αMS‾(mZ)=0.1179(10)(2) by use of (high order) perturbative relations between the effective theory couplings at the charm and beauty quark “thresholds”. The error of this perturbative step is discussed and estimated as 0.0002
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Descrizione: Nucl.Part.Phys.Proc. 285-286 (2017) 132-138
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