2-9 July 2014
Valencia, Spain
Europe/Madrid timezone

Precise alpha_s determination from the low-z parton-to-hadron fragmentation functions

5 Jul 2014, 10:50
Sala 1 ()

Sala 1

Oral presentation Strong Interactions and Hadron Physics Strong Interactions and Hadron Physics


Dr. David d'Enterria (CERN)


We present a new precise method to extract the QCD coupling constant alpha_s from the energy evolution of the moments of the parton-to-hadron fragmentation functions measured in e+e- annihilation and DIS e-p collisions. The evolution of the moments (multiplicity, peak, width, skewness) of the low momentum charged-hadron distribution in jets is computed at NMLLA+NLO accuracy and compared to the experimental data. Values of Lambda_QCD, and corresponding two-loop coupling constant at the Z resonance, are obtained in excellent numerical agreement with the current world average obtained using other methods at NLO accuracy. A detailed study of the (small) systematic uncertainties associated with this procedure will be also presented. [1] R. Perez-Ramos and D. d'Enterria, "Energy evolution of the moments of the hadron distribution in QCD jets including NNLL resummation and NLO running-coupling corrections''; arXiv:1310.8534. [2] D. d'Enterria and R. Perez-Ramos, "Determination of the strong coupling alpha_s from the energy evolution of the distributions of low momentum hadrons in QCD jets", in preparation.

Primary author


Redamy Perez-Ramos (Jyvaskyla Univ.)

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