Lambda-based QCD perturbation theory-: sidestepping the scheme-dependence problem

Abstract

We advocate the replacement of standard alphas(mu)-based QCD perturbation theory, in which the coupling and truncated perturbative predictions are dependent on the chosen renormalisation scheme, by a Lambda-based approach in which QCD observables are directly related to the dimensional transmutation parameter, Lambda, of the theory. The shortcomings of the standard approach are emphasised by formulating it in the Lambda-based language. We show how the Lambda-based approach can be extended to include massive quarks. We also consider the use of Lambda-based perturbation theory in the case when a resummation of large infrared logarithms is required, performing a phenomenological analysis for the e+e- event shape observables thrust and heavy jet mass. We show by fitting to data that smaller power corrections are required than in the standard approach.