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arXiv · 2501.18173

Fits of $\alpha_s$ from event-shapes in the three-jet region: extension to all energies

Paolo Nason·Giulia Zanderighi
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Abstract

This work is an extension of a previous publication [1] where we fitted the strong coupling $\alpha_s$ together with the non-perturbative parameter $\alpha_0$ from event-shape and jet-shape distributions using power corrections computed in the three-jet region. In ref. [1] only ALEPH data at the $Z$-pole were used in the fit. Here, instead, we include a large data sample from various $e^+e^-$ experiments at energies ranging from 22 to 207 GeV and revisited the treatment of theoretical uncertainties. We find that the inclusion of different energies, while not changing the central fit result considerably, helps to disentangle the dependence of perturbative and non-perturbative corrections. Our best fit result is $\alpha_s(M_Z) = 0.1181 (+0.0002 -0.0005) (+0.0018 -0.0021)$, where the first error includes experimental uncertianties and the second one includes uncertainties associated with scale variation, mass effects, fit limits, non-perturbative schemes and non-perturbative uncertainties.

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Paolo Nason, Giulia Zanderighi. 2025-01-30. Fits of $\alpha_s$ from event-shapes in the three-jet region: extension to all energies. https://arxiv.org/abs/2501.18173

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