Testing the running of the QCD coupling in particle energy spectra

Abstract

The spectra of charged particles in the energy variable $\xi =\log 1/x$ (``the hump backed plateau'') are analyzed in terms of moments in order to investigate the sensitivity to the running of ${\alpha }_s$ in particular towards small scales, and to further test thereby the local parton hadron duality picture. The modified leading log approximation (MLLA) of QCD provides a very satisfying description of the $e^{+}{e}^{-}$ data in the full range of c.m. energies from about 1 up to 91 GeV. The same calculation but with fixed coupling ${\alpha }_s$ yields moments which are inconsistent with the data already close to threshold. In particular the soft particles ($E\le 1$~GeV) reflect directly the running of ${\alpha }_s$.

14 pages including 3 figures, uuencoded gz-compressed PS-file

References in corpus (2)

• Measurement of multiplicity and momentum spectra in the current fragmentation region of the Breit frame at HERA
• A Study of the Fragmentation of Quarks in $e^{-}p$ Collisions at HERA

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• Theory of Multiparticle Production in the Soft Region
• Perturbative description of inclusive energy spectra
• Perturbative universality in QCD jet physics
• Perturbative QCD Description of Mean Jet and Particle Multiplicities in e+e- annihilation