On power corrections in the dispersive approach

Power corrections in QCD (both conventional and unconventional ones arising from the ultraviolet region) are discussed within the infrared finite coupling-dispersive approach. It is shown how power corrections in Minkowskian quantities can be derived from the corresponding ones in associated Euclidean quantities through analyticity, allowing a parametrization in term of the Euclidean coupling and a renormalon-free perturbative expansion. A phenomenology of hypothetical 1/Q2 terms of ultraviolet origin is set-up. Models for non-perturbative contributions to the (universal) QCD coupling are suggested. Issues of renormalization scheme dependence are also commented upon. (author)