Test of the flavour independence of αs using next-to-leading order calculations for heavy quarks

OPAL Collaboration (1999) Test of the flavour independence of αs using next-to-leading order calculations for heavy quarks. European Physical Journal C: Particles and Fields, 11 (4). pp. 643-659. ISSN 1434-6044

Abstract

We present a test of the flavour independence of the strong coupling constant for charm and bottom quarks with respect to light (uds) quarks, based on a hadronic event sample obtained with the OPAL detector at LEP. Five observables related to global event shapes were used to measure αs in three flavour tagged samples (uds, c and b). The event shape distributions were fitted by O(α2s) calculations of jet production taking into account mass effects for the c and b quarks. We find: αcs/αuds = 0.997 ± 0.038 (stat.) ± 0.030 (syst.) ± 0.012 (theory) and αbs/αuds = 0.993 ± 0.008 (stat.) ± 0.006 (syst.) ± 0.011 (theory).