The strong coupling and the top quark mass are among the most important parameters in the Standard Model, and measurements with higher-than-current precision will be pursued at future linear colliders. Effective Field Theories provide a framework for efficiently organizing the computations relevant in this context, such as SCET and HQET. Two related aspects that deserve attention are the convergence of perturbative expansions and the size of nonperturbative corrections, that can be studied within the framework of renormalons. In this talk we present all-order results for SCET and bHQET matching coefficients and jet functions in the large-$\beta_0$ limit, as well as for their anomalous dimensions. We also study the MSR short-distance low-scale mass in this limit. Our results point to a possible solution for a long-standing problem with the normalization of differential cross sections for massless and massive quarks, that can have a significant impact on the extraction of $\alpha_s$ and the top quark mass at future linear colliders.
Néstor González Gracia (Salamanca): Toward massless and massive Event Shapes in the large-$\beta_0$ limit
