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Résumé |
The strong coupling constant, $\alpha_s$, is one of the fundamental parameters of
the Standard Model. Its precise determination provides an important test of
Quantum Chromodynamics (QCD) and is essential for precision measurements at
particle colliders, where uncertainties in $\alpha_s$ can affect both theoretical
predictions and the interpretation of experimental results. Reliable
determinations therefore require a careful assessment of perturbative and non-
perturbative effects, as well as a robust understanding of the associated
theoretical uncertainties.
After a brief overview of the current status of ($\alpha_s$) determinations, this
talk will focus on extractions from jet observables and event shapes, highlighting
the discrepancy between determinations based on analytical models of power
corrections, calculated in the two-jet region, and those based on Monte Carlo
event generators. Using the large-$n_f$ limit, we will investigate the impact of
calculating power corrections in the full three-jet region and discuss the
implications for alpha_s determinations.
Finally, we will review recent efforts by a dedicated task force to clarify the
origins of these discrepancies, assess the underlying theoretical assumptions, and
identify a path towards more consistent and reliable determinations of the strong
coupling from jets and event shapes. |
