QCD effects and $b$-tagging at LEP I

Abstract

We analyze the impact of using $b$-tagged samples in studying non-Abelian effects due to QCD in e^+e^-\ar 4jet events at $\sqrt s=M_{Z^0}$, using angular variable analyses and comparisons with e^+e^-\ar 3 \mbox{jet}\gamma events. We find that QCD effects are largely enhanced in $b$-quark samples with respect to `unflavoured' ones, where energy-ordering is used to distinguish between gluon and quark jets. We show that the $b$-quark mass influences the angular distributions significantly and should not be neglectedComment: 16 pages, latex, 11 figures appended (tarred and uuencoded), the complete paper is available via anonymous ftp at ftp://cpt1.dur.ac.uk/pub/preprints/dtp94/dtp94104/ (get dtp94104_*.ps