Hadronization properties of b quarks compared to light quarks in e+e- -> q qbar from 183 to 200 GeV

TL;DR

This study measures the charged particle multiplicity differences in b quark events compared to light quark events at energies 183-200 GeV, confirming QCD predictions and challenging mass-independent models.

Contribution

It provides the first measurements of <n>_{bb} and delta_{bl} at these energies, testing QCD predictions against alternative models.

Findings

Measured delta_{bl} values at 183, 189, and 200 GeV.

Results agree with QCD predictions.

Results disfavor models assuming mass-independent multiplicity.

Abstract

The DELPHI detector at LEP has collected 54 pb^{-1} of data at a centre-of-mass energy around 183 GeV during 1997, 158 pb^{-1} around 189 GeV during 1998, and 187 pb^{-1} between 192 and 200 GeV during 1999. These data were used to measure the average charged particle multiplicity in e+e- -> b bbar events, <n>_{bb}, and the difference delta_{bl} between <n>_{bb} and the multiplicity, <n>_{ll}, in generic light quark (u,d,s) events: delta_{bl}(183 GeV) = 4.55 +/- 1.31 (stat) +/- 0.73 (syst) delta_{bl}(189 GeV) = 4.43 +/- 0.85 (stat) +/- 0.61 (syst) delta_{bl}(200 GeV) = 3.39 +/- 0.89 (stat) +/- 1.01 (syst). This result is consistent with QCD predictions, while it is inconsistent with calculations assuming that the multiplicity accompanying the decay of a heavy quark is independent of the mass of the quark itself.