Abstract:Hadronic Z decay data taken with the ALEPH detector at LEP1 are used to measure the three-jet rate as well as moments of various event-shape variables. The ratios of the observables obtained from b-tagged events and from an inclusive sample are determined. The mass of the b quark is extracted from a fit to the measured ratios using a next-to-leading order prediction including mass effects. Taking the first moment of the y 3 distribution, which is the observable with the smallest hadronization corrections and s… Show more
“…The jet rates (especially the Durham and Cambridge algorithms and certain members of the JADE family) are among the few observables for which the pure NLO calculation gives a reasonable description of the distribution (cf table 3 of [88]). One particularly interesting set of NLO studies makes use of the three-jet rate as a function of y cut (this is just the integral of the distribution of y 23 ) in events with primary b-quarks as compared to light-quark events [176][177][178][179][180] (some of the analyses use other observables, such as the four-jet rate or the thrust). Using NLO calculations which account for massive quarks [181][182][183] makes it possible, in such studies, to extract a value for the b mass at a renormalization scale of M Z , giving first evidence of the (expected) running of the b-quark mass, since all the analyses find M b (M Z ) in the range 2.6-3.3 GeV (with rather variable estimates of the theoretical error).…”
Abstract. This article reviews the status of event-shape studies in e + e − annihilation and DIS. It includes discussions of perturbative calculations, of various approaches to modelling hadronisation and of comparisons to data.
“…The jet rates (especially the Durham and Cambridge algorithms and certain members of the JADE family) are among the few observables for which the pure NLO calculation gives a reasonable description of the distribution (cf table 3 of [88]). One particularly interesting set of NLO studies makes use of the three-jet rate as a function of y cut (this is just the integral of the distribution of y 23 ) in events with primary b-quarks as compared to light-quark events [176][177][178][179][180] (some of the analyses use other observables, such as the four-jet rate or the thrust). Using NLO calculations which account for massive quarks [181][182][183] makes it possible, in such studies, to extract a value for the b mass at a renormalization scale of M Z , giving first evidence of the (expected) running of the b-quark mass, since all the analyses find M b (M Z ) in the range 2.6-3.3 GeV (with rather variable estimates of the theoretical error).…”
Abstract. This article reviews the status of event-shape studies in e + e − annihilation and DIS. It includes discussions of perturbative calculations, of various approaches to modelling hadronisation and of comparisons to data.
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