2000/09/10 by D. V. Shirkov, Shirkov, D. V.
Physics and Astronomy · #Black Holes and Theoretical Physics #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/0009106
12 pages, LaTeX2e
openalex publication_date 2000/09/10 · arxiv created 2001/01/23 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We analyze the effect of π2-terms in the QCD perturbative expansions for the s-channel effective coupling and observables, the effect known from the 80s. We remind that these terms can be collected into specific functions -- strong s-channel coupling \tildaαs and its effective powers \mathfrak A(s) free of ghost singularities. Further on, we study the structure of perturbation theory for observables and its reformulation in terms of nonpower perturbation expansion over the set \\mathfrak A(s)\.\par values of αs as extracted from experiments. The main result is that the common two-loop (NLO, NLLA) approximation widely used in the five-quark (10 \GeV\lesssim √(s)\lesssim 170 \GeV) region for a shape analysis contains a systematic negative error of a 1-2 per cent order of magnitude for the extracted αs(2). Our physical conclusion is that the αs(MZ) value averaged over the f=5 data f=5 ≃ 0.124 appreciably differs from the currently accepted "world average" (=0.118).