Interplay between perturbative and non-perturbative effects with the ARES method

We present a new semi-numerical method to compute leading hadronisationcorrections to two-jet event shapes ine+e−annihilation. The formalism we present utilisesthe dispersive approach, where the magnitude of power corrections is controlled by suitablemoments of an effective strong coupling, but it can be adapted to other methods. We focuson observables where the interplay between perturbative and non-perturbative effects iscrucial in determining the power corrections. A naive treatment of power corrections forsome of these observables gives rise to an unphysical behaviour in the corresponding distri-butions for moderate observable values, thus considerably limiting the available range to fitthe non-perturbative moments. We present a universal treatment to handle such observ-ables, based on a suitable subtraction procedure, and compare our results to the analyticresult in the case of total broadening. Finally, for the first time we present predictions forthe thrust major, which cannot be handled with analytic methods.