Precision Thrust Cumulant Moments at N^3LL

TL;DR

This paper combines high-precision theoretical predictions with experimental data to extract the strong coupling constant and power corrections from thrust cumulant moments, advancing understanding of QCD effects in event shape observables.

Contribution

It provides a novel analysis of thrust cumulants at N^3LL accuracy, including power corrections, to precisely determine alpha_s and higher order power correction parameters.

Findings

Extracted alpha_s(m_Z) = 0.1141 with detailed uncertainties.

Thrust cumulants n > 1 are insensitive to leading power corrections.

Determined higher order power correction parameter ( ilde Omega'_2)^{1/2} = 0.74 GeV.

Abstract

We consider cumulant moments (cumulants) of the thrust distribution using predictions of the full spectrum for thrust including O(alpha_s^3) fixed order results, resummation of singular N^3LL logarithmic contributions, and a class of leading power corrections in a renormalon-free scheme. From a global fit to the first thrust moment we extract the strong coupling and the leading power correction matrix element Omega_1. We obtain alpha_s(m_Z) = 0.1141 \pm (0.0004)_exp \pm (0.0014)_hadr \pm (0.0007)_pert, where the 1-sigma uncertainties are experimental, from hadronization (related to Omega_1) and perturbative, respectively, and Omega_1 = 0.372 \pm (0.044)_exp \pm (0.039)_pert GeV. The n-th thrust cumulants for n > 1 are completely insensitive to Omega_1, and therefore a good instrument for extracting information on higher order power corrections, Omega'_n/Q^n, from moment data. We find (\tilde Omega'_2)^(1/2) = 0.74 \pm (0.11)_exp \pm (0.09)_pert GeV.