Determination of α_s at NLO*+NNLL from a global fit of the low-z parton-tohadron fragmentation functions in e⁺e⁻ and DIS collisions

¹ Sorbonne Université, UPMC Univ Paris 06, UMR 7589, LPTHE, F-75005, Paris, France
² CNRS, UMR 7589, LPTHE, UPMC Univ. Paris 06, BP 126, 4 place Jussieu, F-75252 Paris Cedex 05, France
³ Department of Physics, P.O. Box 35, FI-40014 University of Jyväskylä, Jyväskylä, Finland
⁴ CERN, PH Department, CH-1211 Geneva 23, Switzerland

^a e-mail: perez@lpthe.jussieu.fr
^b e-mail: dde@cern.ch

Published online: 24 March 2015

Abstract

The QCD coupling α_s is determined from a combined analysis of experimental e⁺e⁻ and e^±p jet data confronted to theoretical predictions of the energy evolution of the parton-to-hadron fragmentation functions (FFs) moments –multiplicity, peak, width, skewness– at low fractional hadron momentum z. The impact of approximate next-to-leading order (NLO*) corrections plus next-to-next-to-leading log (NNLL) resummations, compared to previous LO+NLL calculations, is discussed. A global fit of the full set of existing data, amounting to 360 FF moments at collision energies √s ≈ 1–200 GeV, results in α_s(m_Z²) = 0.1189_−0.0014^+0.0025 at the Z mass.