2018 Impact factor 4.843
Particles and Fields


Eur. Phys. J. C 19, 257-268
DOI: 10.1007/s100520100611

Charged multiplicities in Z decays into u, d, and s Quarks

The OPAL Collaboration G. Abbiendi and et al.

Dipartimento di Fisica dell' Università di Bologna and INFN, 40126 Bologna, Italy

(Received: 5 October 2000 / Published online: 15 March 2001 -© Springer-Verlag 2001)

Abstract
About 4.4 million hadronic decays of Z bosons, recorded by the OPAL detector at LEP at a centre-of-mass energy of around $\sqrt{s}= 91.2$ GeV, are used to determine the mean charged particle multiplicities for the three light quark flavours. Events from primary u, d, and s quarks are tagged by selecting characteristic particles which carry a large fraction of the beam energy. The charged particle multiplicities are measured in the hemispheres opposite to these particles. An unfolding procedure is applied to obtain these multiplicities for each primary light quark flavour. This yields $
\langle n_{\mathrm{u}}\rangle=\mathrm{17.77\pm
0.51^{\displaystyle
+0.86}_{...
...angle=\mathrm{20.02\pm
0.13^{\displaystyle
+0.39}_{\displaystyle
-0.37}},
$ where statistical and systematic errors are given. The results for $\langle n_{\mathrm{u}}\rangle$ and $\langle
n_{\mathrm{d}}\rangle$ are almost fully statistically anti-correlated. Within the errors the result is consistent with the flavour independence of the strong interaction for the particle multiplicities in events from the light up, down, and strange quarks.



© Società Italiana di Fisica, Springer-Verlag 2001