QCD Description of Particle Spectra up to LEP-1.5 Energies and the Running of ${\alpha }_s$

Abstract

Recent results on the energy spectra in QCD jets are reported. Within the Modified Leading Logarithmic Approximation (MLLA) and the Local Parton Hadron Duality (LPHD) model one finds a very good description of the $e^{+}{e}^{-}$ data from the lowest up to the LEP 1.5 energies. A model with fixed ${\alpha }_s$ can be excluded, already in certain finite energy intervals. The fits also extrapolate smoothly into the region of small particle energies, in particular, the data follow a scaling prediction for the low energy limit derived from the colour coherence of the soft gluon emission.

Comments: LaTeX, 6 pages, 3 figures, uses stwol.sty and epsfig.sty, to appear in the Proc. of the 28th International Conference on High Energy Physics, 25-31 July 1996, Warsaw, Poland