QCD effects and $b$-tagging at LEP I

We analyze the impact of using $b$-tagged samples in studying non-Abelian effects due to QCD in $e^{+}{e}^{-}\text{ar}4$jet events at $\sqrt{s}=M_{Z^0}$, using angular variable analyses and comparisons with $e^{+}{e}^{-}\text{ar}3jet\gamma$ 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 neglected