Aggarwal, M.M.
OPAL
E+ E- --> 3JET
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Measurement of three jet distributions sensitive to the gluon spin in e+ e- annihilations at S**(1/2) = 91-GeV

The OPAL collaboration Alexander, G. ; Allison, John ; Allport, P.P. ; et al.
Z.Phys.C 52 (1991) 543-550, 1991.
Inspire Record 317142 DOI 10.17182/hepdata.14852

None

4 data tables
Table 1

Data at Parton level.

Table 2

Ratio data/(Monte Carlo) at Parton level.

Table 3

Data at Parton level.. Distribution of Ellis-Karliner angle.

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A Direct observation of quark - gluon jet differences at LEP

The OPAL collaboration Alexander, G. ; Allison, J. ; Allport, P.P. ; et al.
Phys.Lett.B 265 (1991) 462-474, 1991.
Inspire Record 316872 DOI 10.17182/hepdata.48454

Quark and gluon jets in e + e − three-jet events at LEP are identified using lepton tagging of quark jets, through observation of semi-leptonic charm and bottom quark decays. Events with a symmetry under transposition of the energies and directions of a quark and gluon jet are selected: these quark and gluon jets have essentially the same energy and event environment and as a consequence their properties can be compared directly. The energy of the jets which are studied is about 24.5 GeV. In the cores of the jets, gluon jets are found to yield a softer particle energy spectrum than quark jets. Gluon jets are observed to be broader than quark jets, as seen from the shape of their particle momentum spectra both in and out of the three-jet event plane. The greater width of gluon jets relative to quark jets is also visible from the shapes of their multiplicity distributions. Little difference is observed, however, between the mean value of particle multiplicity for the two jet types.

1 data table
Table 1

QUARK means QUARK or QUARKBAR.


A Study of Jet Production Rates and a Test of QCD on the Z0 Resonance

The OPAL collaboration Akrawy, M.Z. ; Alexander, G. ; Allison, J. ; et al.
Phys.Lett.B 235 (1990) 389-398, 1990.
Inspire Record 283783 DOI 10.17182/hepdata.29753

Relative production rates of multijet hadronic final states of Z 0 boson decays, observed in e + e − annihilation around 91 GeV centre of mass energy, are presented. The data can be well described by analytic O( α s 2 ) QCD calculations and by QCD shower model calaculations with parameters as determined at lower energies. A first judgement of Λ MS and of the renormalization scale μ 2 in O( α s 2 ) QCD results in values similar to those obtained in the continuum of e + e − annihilations. Significant scaling violations are observed when the 3-jet fractions are compared to the corresponding results from smaller centre of mass energies. They can be interpreted as being entirely due tot the energy dependence of α s , as proposed by the nonabelian nature of QCD, The possibility of an energy independent coupling constant can be excluded with a significance of 5.7 standard deviations.

1 data table
Table 1

Data are corrected for final acceptance and resolution of the detector. No explicit corrections for hadronisation effects are applied.