2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 13, 573-589
DOI 10.1007/s100520000313

Measurement of the gluon fragmentation function and a comparison of the scaling violation in gluon and quark jets

The DELPHI Collaboration

P.Abreu22 - et al.

22 LIP, IST, FCUL - Av. Elias Garcia, 14-1o, 1000 Lisboa Codex, Portugal

Received: 5 November 1999 / Published online: 25 February 2000 - © Springer-Verlag 2000

Abstract
The fragmentation functions of quarks and gluons are measured in various three-jet topologies in Z decays from the full data set collected with the DELPHI detector at the Z resonance between 1992 and 1995. The results at different values of transverse momentum-like scales are compared. A parameterization of the quark and gluon fragmentation functions at a fixed reference scale is given. The quark and gluon fragmentation functions show the predicted pattern of scaling violations. The scaling violation for quark jets as a function of a transverse momentum-like scale is in a good agreement with that observed in lower energy $\mbox{e}^+\mbox{e}^-$ annihilation experiments. For gluon jets it appears to be significantly stronger.
The scale dependences of the gluon and quark fragmentation functions agree with the prediction of the DGLAP evolution equations from which the colour factor ratio CA/CF is measured to be:

\begin{eqnarray*}\frac{C_A}{C_F} = 2.26 \pm 0.09_{stat.} \pm 0.06_{sys.}
\pm 0.12_{clus.,scale}\, .
\end{eqnarray*}



Copyright Società Italiana di Fisica, Springer-Verlag 2000