General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 29 Jun 2019 Physics Letters B 286 (1992) We present a study of the inclusive ~/ production based on 300000 hadronic Z ° decays. The measured inclusive momentum distribution can be reproduced by parton shower Monte Carlo programs and also by an analytical QCD calculation. Comparing our results with low energy e+e -data, we find that QCD describes both the shape and the energy evolution of the r/ spectrum. The comparison of q production rates in quark-and gluon-enriched jet samples does not show statistically significant evidence for more abundant production of q mesons in gluon fragmentation. l Deceased. 2 Supported by the German Forschung und Technologie. Bundesministerium f'ti