# High precision determination of $\alpha_s$ from a global fit of jet rates

## TL;DR

This paper achieves a highly precise measurement of the strong coupling constant _s by fitting jet rates in electron-positron collisions using advanced theoretical predictions, reducing uncertainties and aligning with the world average.

## Contribution

It provides the first extraction of _s using Nb0LO+NNLL predictions for jet rates, incorporating correlations and a comprehensive data set from multiple colliders.

## Key findings

- _s(M_Z) = 0.11881 b1 0.00133 total uncertainty
- Perturbative uncertainty is smaller than hadronization uncertainty
- Results agree with the latest world average

## Abstract

We present state-of-the-art extractions of the strong coupling based on N$^3$LO+NNLL accurate predictions for the two-jet rate in the Durham clustering algorithm at $e^+e^-$ collisions, as well as a simultaneous fit of the two- and three-jet rates taking into account correlations between the two observables. The fits are performed on a large range of data sets collected at LEP and PETRA colliders, with energies spanning from $35$ GeV to $207$ GeV. Owing to the high accuracy of the predictions used, the perturbative uncertainty is considerably smaller than that due to hadronization. Our best determination at the $Z$ mass is $\alpha_s(M_Z) = 0.11881 \pm 0.00063(exp.) \pm 0.00101(hadr.) \pm 0.00045(ren.) \pm 0.00034(res.)$, which is in agreement with the latest world average and has a comparable total uncertainty.