Abstract:
Electron-positron event shapes are among the oldest and most established observables for extracting the strong coupling constant. The most precise determinations based on the thrust and C-parameter distributions yielded values, however, that are currently in tension with the PDG world average. We therefore revisited the theoretical foundation of the event-shape fits, in particular their implementation of non-perturbative effects.
Interestingly, we found that the combined effect of altering the renormalon subtraction scheme and perturbative scale parameters can lead to a few-percent-level impacts on the extracted alpha_s value, indicating a potentially important systematic theory uncertainty that should be accounted for.
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Meeting ID: 933 4269 3866 Passcode: 185096