Power corrections and renormalon resummation for the average thrust

Abstract

Infrared power corrections for the average thrust < T > in e+e- annihilation are analyzed in the framework of renormalon resummation, motivated by analogy with the skeleton expansion in QED and the BLM approach. Performing the ``massive gluon'' renormalon integral a renormalization scheme invariant result is obtained. We find that a major part of the discrepancy between the known next-to-leading order (NLO) calculation and experiment can be explained by resummation of higher order perturbative terms. This fact does not preclude the infrared finite coupling interpretation with a substantial 1/Q power term. Fitting the regularized perturbative sum plus a 1/Q term to experimental data yields alpha_s^{MSbar}(M_Z)=0.110 \pm 0.006.

Comments: Talk given by E. Gardi at the QCD'99 conference, Montpellier, July 1999. 4 pages, 3 figures