Energy evolution of the moments of the hadron distribution in QCD jets including NNLL resummation and NLO running-coupling corrections
Redamy Pérez-Ramos (Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), F-40014 Jyväskylä, Finland); David d’Enterria (CERN, PH Department, CH-1211 Geneva 23, Switzerland)
The moments of the single inclusive momentum distribution of hadrons in QCD jets, are studied in the next-to-modified-leading-log approximation (NMLLA) including next-to-leading-order (NLO) corrections to the α s strong coupling. The evolution equations are solved using a distorted Gaussian parametrisation, which successfully reproduces the spectrum of charged hadrons of jets measured in e + e − collisions. The energy dependencies of the maximum peak, multiplicity, width, kurtosis and skewness of the jet hadron distribution are computed analytically. Comparisons of all the existing jet data measured in e + e − collisions in the range s ≈ 2 − 200 $$ \sqrt{\mathrm{s}}\approx 2-200 $$ GeV to the NMLLA + NLO * predictions allow one to extract a value of the QCD parameter Λ QCD , and associated two-loop coupling constant at the Z resonance α s (m Z 2 ) = 0.1195 ± 0.0022, in excellent numerical agreement with the current world average obtained using other methods.
