Strong Coupling Constant Determination from Dijet Events in Thrust

by Gherardo Vita

Monday 10 Feb 2025, 14:00 → 16:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

In this talk I will present a determination of the strong coupling constant from a global analysis of thrust data in electron-positron annihilation, updating the 2010 analysis by Abbate et al. and restricting the dataset to a region which is more clearly dominated by dijet events.
I'll motivate the theoretical framework showing that the hierarchy between physical scales entering the thrust distribution naturally organizes it in regions with clearly defined and improvable expansions. 
I'll discuss the leading power description of the dijet region and how to systematically include non-perturbative corrections via well-defined quantum field theory objects. 
I'll detail the new ingredients that have become available in recent years, discuss their impact on the fits, and highlight the importance of higher-order resummation in ensuring the convergence and stability of results.
Special emphasis will be placed on the validation of the dijet factorization approach, the impact of three-jet power corrections, hadron mass effects, as well as the estimate of perturbative uncertainties, including the sensitivity to various renormalon gap subtraction schemes.
Our refined analysis yields αs(mZ) = 0.1136 ± 0.0012 with chi^2/dof = 0.86 in very good agreement with data outside of the fit range and fully compatible with earlier results using a larger fit range.
I will conclude with an outlook on further theory improvements for the strong coupling determination from event shapes, and the role of new experimental data from future (and past) experiments.