NAIVE NONABELIANIZATION AND RESUMMATION OF FERMION BUBBLE CHAINS

We propose to extend the Brodsky-Lepage-Mackenzie scale-fixing prescri ption by resumming exactly any number of one-loop vacuum polarization insertions into one-loop diagrams. In this way, one makes maximal use of the information contained in one-loop perturbative corrections comb ined with the one-loop running of the effective coupling. The scale am biguity at leading order is converted into an intrinsic uncertainty of perturbative approximations induced by IR renormalons. Practical impl ementation of this resummation requires only knowledge of one-loop rad iative corrections with non-vanishing gluon mass. We find that higher order corrections to the pole mass and the top quark decay width are d ominated by renormalons already in low orders and demonstrate the impa ct of eliminating the pole mass on the convergence of the perturbative series.