Eur. Phys. J. C (2010) 67: 57-72
https://doi.org/10.1140/epjc/s10052-010-1288-4

Regular Article - Theoretical Physics

Hadronisation effects in event-shape moments

Institut für Theoretische Physik, Universität Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland

^* e-mail: luisonig@physik.uzh.ch

Received: 17 December 2009
Revised: 9 February 2010
Published online: 27 March 2010

Abstract

We study the moments of hadronic event shapes in e ⁺ e ⁻ annihilation within the context of next-to-next-to-leading order (NNLO) perturbative QCD predictions combined with non-perturbative power corrections in the dispersive model. This model is extended to match the NNLO perturbative prediction. The resulting theoretical expression has been compared to experimental data from JADE and OPAL, and a new value for α _s (M _Z ) has been determined, as well as of the average coupling α ₀ in the non-perturbative region below μ _I =2 GeV within the dispersive model: The precision of the α _s (M _Z ) value has been improved in comparison to the previously available next-to-leading order analysis. We observe that the resulting power corrections are considerably larger than those estimated from hadronisation models in multi-purpose event generator programs.