Fits of αs using power corrections in the three-jet region

Abstract

In this work we study the impact of recent findings regarding non-perturbative corrections in the three-jet region to e+e− hadronic observables, by performing a simultaneous fit of the strong coupling constant αs and the non-perturbative parameter α0. We extend the calculation of these power corrections, already known for thrust and C-parameter, to other e+e− hadronic observables. We find that for some observables the non-perturbative corrections are reasonably well behaved in the two-jet limit, while for others they have a more problematic behaviour. If one limits the fit to the three-jet region and to the well-behaved observables, one finds in general very good results, with the extracted value of αs agreeing well with the world average. This is the case in particular for the thrust and C-parameter for which notably small values of αs have been reported when non-perturbative corrections have been computed using analytic methods. Furthermore, the more problematic variables are also well described provided one stays far enough from the two-jet limit, while in this same region they cannot be described using the traditional implementation of power-corrections based on two-jet kinematics.