Résumé
We re-examine a modification of perturbative expansions, valid for asymptotically free theories, producing “variationally improved” expansions of physical quantities relevant to dynamical (chiral) symmetry breaking. The large order behaviour of this expansion is drastically improved, with respect to the original perturbative expansion (making the series at least Borel summable, in a certain range of renormalization scheme parameters). We argue that non-perturbative estimates of the order parameters of QCD chiral symmetry breaking are therefore possible in this framework.