Speaker
Description
The decoupling strategy by the ALPHA collaboration uses simultaneous decoupling of $N_{\rm f}=3$ heavy quark flavours to obtain a controlled connection between the $\Lambda$-parameters in QCD with $N_{\rm f}=3$ and $N_{\rm f}=0$ quark flavours, respectively, in terms of a common decoupling scale. Corrections are either power suppressed in the heavy quark mass, or perturbatively suppressed by powers of $\alpha_s$ at the scale of the heavy quark mass. In this talk I review the theoretical formalism (for results cf.~subsequent talk by R.~H\"ollwieser).
The Symanzik effective theory and the heavy quark mass expansion are combined and analyzed using recent results by Husung et al. on the leading logarithmic modifications of powers in $a$ or the inverse quark mass. The application to finite volume couplings in a gradient flow scheme, together with perturbative 4-loop results on decoupling from the literature, then yield the basis for the analysis of the continuum and decoupling limits.
