Hadron masses and power corrections to event shapes
G. P. Salam, D. Wicke
TL;DR
This work shows that hadron masses induce significant, non-universal power corrections to event-shape observables beyond the traditional 1/Q term, scaling like $(\ln Q)^A/Q$ with $A\approx1.6$. Using an extended tube-model framework, the authors derive mass-dependent corrections characterized by $\delta c_V$ functions and show how mass effects break simple universality in the general scheme, while preserving a universal structure in the $E$-scheme where mass contributions align with the same $c_V$ coefficient. They provide explicit expressions for mass corrections across key observables, analyze their impact in comparison with Monte Carlo generators, and discuss implications for extracting perturbative and non-perturbative parameters. The results suggest the possibility of disentangling traditional hadronisation from mass-related effects in fits to data, with practical guidance on observable definitions and scheme choices.
Abstract
It is widely believed that hadronisation leads to 1/Q corrections to e+e- event shapes. We show that there are further corrections, proportional to (ln Q)^A/Q with A=4C_A/beta_0~=1.6, associated with hadron masses and whose relative normalisations can be calculated from one observable to another. At today's energies these extra corrections can be of the same order of magnitude as `traditional' 1/Q corrections. They fall into two classes: universal and non-universal. The latter can be eliminated by suitable redefinitions of the observables.