Measurement of the charged multiplicity of events containing bottom hadrons atEc.m.=91GeV

Abstract

Using an impact parameter tag to select an enriched sample of 2'-+ bb events, we have measured the difference between the average charged multiplicity of bb and all hadronic 2' decays to be 2.1&1.8(stat)f0.6(sys) tracks per event. The resulting

Multiplicity difference between heavy- and light-quark jets revisited

“…The experimental measurements of hadron multiplicities in bb and cc events produced in e + e − annihilation were performed in the wide range of c.m.s. energies √ s ≡ W from PEP, at √ s = 29 GeV, to LEP2 at √ s = 206 GeV [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]. For reviews on this topic see, for instance, [46][47][48].…”

Hadronization in decay

“…In addition to studies of the natural flavour mix, light and heavy quark initiated events have been investigated separately [108,109]. A large quark mass reduces phase space and shields the the collinear singularity associated with forward gluon emission, causing a relative suppression of forward hadrons [19].…”

“…A large quark mass reduces phase space and shields the the collinear singularity associated with forward gluon emission, causing a relative suppression of forward hadrons [19]. In practice observation of the reduction in associated multiplicity due to this 'dead cone' [110] is hampered by the presence of the heavy hadron's decay tracks (5.5±0.1 per b-hadron [109]) which actually ensure a higher multiplicity than in u,d,s events. However the difference in multiplicity is predicted [111] and seen to be √ s independent [108,109,112].…”

“…In practice observation of the reduction in associated multiplicity due to this 'dead cone' [110] is hampered by the presence of the heavy hadron's decay tracks (5.5±0.1 per b-hadron [109]) which actually ensure a higher multiplicity than in u,d,s events. However the difference in multiplicity is predicted [111] and seen to be √ s independent [108,109,112]. (A variation of 0.4 tracks is expected from the change in the heavy quark fraction between 12 (Υ(4S)) and 91 (Z 0 ) GeV [109]; this is below the level of the experimental errors).…”

“…However the difference in multiplicity is predicted [111] and seen to be √ s independent [108,109,112]. (A variation of 0.4 tracks is expected from the change in the heavy quark fraction between 12 (Υ(4S)) and 91 (Z 0 ) GeV [109]; this is below the level of the experimental errors).…”