2013/10/24 by Jean-Loı̈c Kneur, Kneur, J-L., André Neveu +1
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.1310.6724
openalex publication_date 2013/10/24 · openalex created_date 2019/06/27 · openalex updated_date 2026/07/28
A new version of the so-called optimized perturbation (OPT), implementing consistently renormalization group properties, is used to calculate the nonperturbative ratio Fπ/Λ of the pion decay constant and the basic QCD scale in the MS scheme. Using the experimental Fπ input value it provides a new determination of Λ for nf=2 and nf=3, and of the QCD coupling constant αS at various scales once combined with a standard perturbative evolution. The stability and empirical convergence properties of the RGOPT modified series is demonstrated up to the third order. We examine the difference sources of theoretical uncertainties and obtain αS (mZ) =0.1174 +.0010-.0005 ± .001 ± .0005evol, where the first errors are estimates of the intrinsic theoretical uncertainties of our method, and the second errors come from present uncertainties in Fπ/F0, where F0 is Fπ in the exact chiral SU(3) limit.