Abstract
We consider a method for determining the QCD strong coupling constant using fits of perturbative predictions for event shape averages to data collected at the LEP, PETRA, PEP and TRISTAN colliders. To obtain highest accuracy predictions we use a combination of perturbative {{{mathcal {O}}}}(alpha _{S}^{3}) calculations and estimations of the {{{mathcal {O}}}}(alpha _{S}^{4}) perturbative coefficients from data. We account for non-perturbative effects using modern Monte Carlo event generators and analytic hadronization models. The obtained results show that the total precision of the alpha _{S} determination cannot be improved significantly with the higher-order perturbative QCD corrections alone, but primarily requires a deeper understanding of the non-perturbative effects.
Highlights
Measurements using hadronic final states in e+e− annihilation have provided detailed experimental tests of Quantum Chromodynamics (QCD), the theory of the strong interaction in the Standard Model
Differential perturbative QCD (pQCD) calculations for the production of three partonic jets in e+e− hadronic annihilation are available to O(αS3) accuracy [1,2,3,4,5,6], which corresponds to next-to-nextto-leading order (NNLO) in QCD perturbation theory for this process
When confronting calculations based on QCD perturbation theory with data, it must be kept in mind that in e+e− annihilation strong interactions occur only in the final state, the observed quantities are affected by hadronization and power corrections
Summary
Measurements using hadronic final states in e+e− annihilation have provided detailed experimental tests of Quantum Chromodynamics (QCD), the theory of the strong interaction in the Standard Model These measurements were based on comparisons of moments and differential distributions of event shapes or jet rates to perturbative predictions. When confronting calculations based on QCD perturbation theory (of any order) with data, it must be kept in mind that in e+e− annihilation strong interactions occur only in the final state, the observed quantities are affected by hadronization and power corrections These corrections must either be extracted from Monte Carlo predictions or computed using analytic models. We expect that the presented analysis will provide valuable input for the planing of αS(MZ ) measurements and data taking at future e+e− facilities
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