Related papers: Unbiased gluon jet multiplicity from e$^+$e$^-$ th…
The charged particle multiplicities of two- and three-jet events from the reaction e+e- -> Z0 -> hadrons are measured for Z0 decays to light quark (uds) flavors. Using recent theoretical expressions to account for biases from event…
The charged particle multiplicity in hadronic three-jet events from Z decays is investigated. The topology dependence of the event multiplicity is found to be well described by a modified leading logarithmic prediction. A parameter fit of…
Three jet events arising from decays of the $Z^0$ boson, collected by the DELPHI detector at LEP, were used to measure differences in the properties of quark and gluon jet fragmentation. Gluon jets were anti-tagged in $b\bar{b}g$ events, by…
We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e+e- annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria.…
Gluon jets are identified in e+e- hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this…
Gluon jets are identified in hadronic Z0 decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet…
We compared the multiplicities of pizero, eta, Kzero and of charged particles in quark and gluon jets in 3-jet events, as measured by the OPAL experiment at LEP. The comparisons were performed for distributions unfolded to 100% pure quark…
A thorough verification of the distinct differences in the properties of quark and gluon jets is considered as one of the most instructive tests of the basic ideas of QCD. In the real life experiments such a comparison appears to be quite a…
Distinguishing quark-initiated jets from gluon-initiated jets has the potential to significantly improve the reach of many beyond-the-standard model searches at the Large Hadron Collider and to provide additional tests of QCD. To explore…
The properties of quark and gluon jets depend on jet definitions and event selection. I discuss how these can be included in calculations and present jet definitions designed to give unbiased jets.
Flavour inclusive, udsc and b fragmentation functions in unbiased jets, and flavour inclusive, udsc, b and gluon fragmentation functions in biased jets are measured in e+e- annihilations from data collected at centre-of-mass energies of…
We discuss some important issues concerning multiplicities in quark and gluon jets in e+e- annihilation. In QCD the properties of a jet in general depend on two scales, the energy and virtuality of the jet. Frequently theoretical…
Three recent OPAL studies are presented in which the fragmentation process in quark and gluon jets and in identified up, down and strange flavour jets is studied. The first is a measurement of charged particle, pi0, eta and K0…
Differences between the properties of gluon and quark jets have been convincingly established by experiments at LEP. Quantitative tests of QCD analytic predictions for these differences have not been possible, however, because of…
We measure the subjet multiplicity M in jets reconstructed with a successive combination type of jet algorithm (k_T). We select jets with 55<E_T<100 GeV and | \eta | < 0.5. We compare similar samples of jets at sqrt{s} = 1800 and 630 GeV.…
A new method to identify the gluon jet in 3-jet ``{\bf Y}'' decays of $Z^0$ is presented. The method is based on differences in particle multiplicity between quark jets and gluon jets, and is more effective than tagging by leptonic decay.…
We measure the subjet multiplicity M in jets reconstructed with a successive combination type of jet algorithm (kT). We select jets with 55<pT<100 GeV and |eta|<0.5. We compare similar samples of jets at sqrt(s)=1800 and 630 GeV. The HERWIG…
The difference between the ratio of multiplicities and the ratio of their derivatives on energy for gluon and quark jets is calculated up to next-to-next-to leading order of perturbative QCD. Its non-zero value is uniquely defined by the…
Recent developments and results on the comparison of gluon to quark jets are discussed. A most important topic is the introduction of explicit energy scales of the jets. The scaling violation of the fragmentation function and the increase…
Using data collected with the CLEO II detector at the Cornell Electron Storage Ring, we determine the ratio R(chrg) for the mean charged multiplicity observed in Upsilon(1S)->gggamma events, to the mean charged multiplicity observed in e+e-…