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 − → 4jet events at √ s = M Z 0 , using angular variable analyses and comparisons with e + e − → 3jetγ events. We find that QCD effects are largely enhanced in b-quark samples with respect to 'unflavoured' ones, where energyordering 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.

Full one-loop electro-weak corrections to three-jet observables at theZpole and beyond

“…Another relevant phenomenological aspect of our calculation would pertain to the case in which the bremsstrahlung photon is resolved, so that a three-jet plus one-photon sample can be defined and compared to a four-jet sample in order to extract genuine non-Abelian QCD effects, as detailed in[17] -and references therein -but we postpone this analysis to a future work.…”