DOI 10.1007/s100520000474
Measurements of the structure of quark
and gluon jets in hadronic Z decays
The ALEPH Collaboration
R. Barate - et al.
Laboratoire de Physique des Particules (LAPP), IN2P3-CNRS,
74019 Annecy-le-Vieux Cedex, France
Received: 2 February 1998 / Published online: August 9, 2000 - © Springer-Verlag 2000
Abstract
An experimental investigation of the structure of
identified quark and gluon jets is presented. Observables related to both
the global and internal structure of jets are measured; this allows for
tests of QCD over a wide range of transverse momentum scales.
The observables include distributions of jet-shape variables, the mean
and standard deviation of the subjet multiplicity distribution
and the fragmentation function for charged particles. The data
are compared with predictions of perturbative QCD as well as QCD-based
Monte Carlo models. In certain kinematic regions the measurements are
sensitive mainly to perturbatively calculable effects, allowing for
a test of QCD. The comparisons are also extended into
regions where nonperturbative effects become large, and in this way
the transition from hard to soft QCD is investigated.
It is found that by including leading and next-to-leading
logarithmic contributions in the QCD predictions, the agreement with the
data can be extended to lower transverse momentum scales, especially
for gluon jets.
Copyright Società Italiana di Fisica, Springer-Verlag 2000
