Leading power corrections in the ARES method

by Basem El-Menoufi

Monday Jan 22, 2024, 2:00 PM → 4:00 PM Europe/Zurich

4/3-006 - TH Conference Room (CERN)

It is well known that event shapes in e⁺e⁻ → hadrons receive linear power corrections, proportional to Λ_QCD/Q, from hadronization effects. Accurate fits of the strong coupling from event shapes’ data is impossible without understanding of power corrections. I present a new semi-numerical method to compute leading hadronisation corrections to two-jet event shapes in e⁺e⁻ annihilation. The formalism utilises the dispersive approach, where the magnitude of power corrections is controlled by suitable moments of an effective strong coupling, but it can be adapted to other methods. I focus on observables where the interplay between perturbative and non-perturbative effects is crucial in determining the power corrections. A naive treatment of power corrections for some of these observables gives rise to an unphysical behaviour in the corresponding distributions for moderate observable values, thus considerably limiting the available range to fit the non-perturbative moments and likewise for αs. I present a universal treatment to handle such observables, based on a suitable subtraction procedure, and compare the results to the known analytic result in the case of total broadening. Finally, for the first time I present predictions for the thrust major, which cannot be handled with analytic methods.

ElMenoufi_220124.pdf