2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/200090Within the set of schemes defined by generalized, manifestly gauge invariant exact renormalization groups for QED, it is argued that the beta-function in the four dimensional massless theory cannot possess any nonperturbative power corrections. Consequently, the perturbative expression for the beta-function must be resummable. This argument cannot be extended to flows of the other couplings or to the anomalous dimension of the fermions and so perturbation theory does not define a unique trajectory in the critical surface of the Gaussian fixed point. Thus, resummability of the beta-function is not inconsistent with the expectation that a non-trivial fixed point does not exist.7 pages, 2 figs; v2 published version, some very minor rewording; v3 typo correctedHigh Energy Physics - TheoryHigh Energy Physics - Phenomenologytext