Binkley, M.E.
E+ E- --> 3JET
DSIG/DX
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Investigation of the splitting of quark and gluon jets.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 4 (1998) 1-17, 1998.
Inspire Record 467927 DOI 10.17182/hepdata.49547

The splitting processes in identified quark and gluon jets are investigated using longitudinal and transverse observables. The jets are selected from symmetric three-jet events measured in Z decays with the Delphi detector in 1991-1994. Gluon jets are identified using heavy quark anti-tagging. Scaling violations in identified gluon jets are observed for the first time. The scale energy dependence of the gluon fragmentation function is found to be about two times larger than for the corresponding quark jets, consistent with the QCD expectation CA/CF. The primary splitting of gluons and quarks into subjets agrees with fragmentation models and, for specific regions of the jet resolution y, with NLLA calculations. The maximum of the ratio of the primary subjet splittings in quark and gluon jets is 2.77±0.11±0.10. Due to non-perturbative effects, the data are below the expectation at small y. The transition from the perturbative to the non-perturbative domain appears at smaller y for quark jets than for gluon jets. Combined with the observed behaviour of the higher rank splittings, this explains the relatively small multiplicity ratio between gluon and quark jets.

14 data tables
Table 1

Scaled energy distribution of charged hadrons produced in Quark jets in 'Y'topology 3-JET events.

Table 2

Scaled energy distribution of charged hadrons produced in Gluon jets in 'Y'topology 3-JET events.

Table 3

Scaled energy distribution of charged hadrons produced in Quark jets in 'Mercedes' topology 3-JET events.

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Comparison of Inclusive Fractional Momentum Distributions of Quark and Gluon Jets Produced in $e^+ e^-$ Annihilation

The TASSO collaboration Braunschweig, W. ; Gerhards, R. ; Kirschfink, F.J. ; et al.
Z.Phys.C 45 (1989) 1, 1989.
Inspire Record 277210 DOI 10.17182/hepdata.15299

Inclusive charged particle production ine+e− annihilation into hadrons is studied in terms of the particle fractional momentumxp. Thexp distribution for gluon jets is extracted by comparing two data samples measured in the TASSO detector: nearly symmetric three jet events at centre-of-mass energyW∼35 GeV and two jet events atW∼22 GeV, yielding quark and gluon jets of similar energies (∼11.5 GeV). No significant difference is observed between quark and gluon jets. Monte Carlo models based on parton showers describe the trend and energy variation of the data better than a model with second order matrix element in αs.

3 data tables
Table 1

2 JET data at sqrt(s) = 35 GeV.

Table 2

3 JET data at sqrt(s) = 22 GeV.

Table 3

Gluon jet data at sqrt(s) = 11.5 GeV.


Inclusive Charged Particle Distribution in Nearly Threefold Symmetric Three Jet Events at $e$({CM}) = 29-{GeV}

Petersen, A. ; Abrams, G.S. ; Amidei, D. ; et al.
Phys.Rev.Lett. 55 (1985) 1954, 1985.
Inspire Record 216850 DOI 10.17182/hepdata.20285

We report a measurement of the inclusive charged-particle distribution for gluon jets derived from nearly threefold-symmetric three-jet events taken at center-of-mass energy of 29 GeV in e+e− annihilation. The charged-particle spectrum for these jets is observed to fall off more rapidly than those of quark jets of the same energy.

1 data table
Table 1

Errors include both statistics and the uncertainty in correction factors. X is defined at the energy of the individual particle divided by the total energy of the jet to which it is assigned.