Determining the strong coupling from fits to thrust and heavy-jet-mass

by Vicent Mateu (University of Salamanca)

Tuesday 27 Jan 2026, 11:00 → 13:00 Europe/Berlin

PH 3344, (5101.01.344) (TUM, Physics Department, Garching)

I will present results for determinations of the strong coupling from fits to the thrust and heavy-jet-mass distributions using theoretical predictions at N³LL + O(α_s³), including renormalon subtractions and non-perturbative power corrections. Data from LEP and other e⁺e^- colliders are used, covering center-of-mass energies between 35 GeV and 207 GeV. I will show that resummation is essential to obtain stable extractions that are not overly sensitive to the choice of datasets. For thrust, fits are restricted to the dijet region, and the impact of non-constant power corrections and different gap-subtraction schemes is studied. For heavy-jet mass, shoulder resummation at NLL and an independent three-jet power-correction parameter are included; with these improvements, values as large as ρ = 0.3 can be included in the fit. Perturbative uncertainties are estimated using a random-scan method for thrust, while for heavy-jet mass a theoretical covariance matrix is employed in the fits.

MateuEShapes.pdf