HEPData Search

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Determination of $alpha_{s}$ in second order {QCD} from hadronic $Z$ decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.

Z.Phys.C 54 (1992) 55-74, 1992.

Inspire Record 333272 DOI 10.17182/hepdata.14603

Distributions of event shape variables obtained from 120600 hadronicZ decays measured with the DELPHI detector are compared to the predictions of QCD based event generators. Values of the strong coupling constant αs are derived as a function of the renormalization scale from a quantitative analysis of eight hadronic distributions. The final result, αs(MZ), is based on second order perturbation theory and uses two hadronization corrections, one computed with a parton shower model and the other with a QCD matrix element model.

9 data tables

Table 1

Experimental differential Thrust distributions.

Table 2

Experimental differential Oblateness distributions.

Table 3

Experimental differential C-parameter distributions.

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Study of electron pair production below the Z mass at the CERN anti-p p collider

The UA2 collaboration Alitti, J. ; Ambrosini, G. ; Ansari, R. ; et al.

Phys.Lett.B 275 (1992) 202-208, 1992.

Inspire Record 322265 DOI 10.17182/hepdata.27115

Results on the cross section for the production of electron pairs in p p collisions at √ s = 630 GeV are presented. The measured value is σ = 405 ± 51 (syst.) ± 84 (syst.) pb, in the invariant mass interval 10 < m < 70 GeV. The results are compared to recent theoretical calculations which include O( α s 2 ) QCD contributions. The comparison of these data with those of lower energy experiments show approximate scaling as a function of the variable √τ = m √s .

3 data tables

Table 1

No description provided.

Table 2

Statistical and systematic errors combined.

Table 3

Statistical errors only.

A Study of Three Jet Events at the {CERN} $\bar{p} p$ Collider

The UA2 collaboration Appel, J.A. ; Bagnaia, P. ; Banner, M. ; et al.

Z.Phys.C 30 (1986) 341, 1986.

Inspire Record 219453 DOI 10.17182/hepdata.15897

The UA2 experiment, running at the CERN SPS$\bar pp$ Collider, has performed a study of events containing three hard jets in the final state. The angular distributions of the three jets show evidence for gluon bremsstrahlung, in good agreement with a QCD model to leading order in the strong coupling constant αs. The yield of three-jet events relative to that of two-jet events provides a measure of the strong coupling constant: ;3K3/K2=0.23±0.01±0.04, whereK2 andK3 represent the contributions arising from higher order corrections in α3 to the two- and three-jet exclusive cross-sections. A detailed discussion of the systematic and theoretical uncertainties is given.

1 data table

Table 1

No description provided.

Measurement of Very Large Transverse Momentum Jet Production at the CERN anti-p p Collider

The UA2 collaboration Bagnaia, P. ; Banner, M. ; Battiston, R. ; et al.

Phys.Lett.B 138 (1984) 430-440, 1984.

Inspire Record 199645 DOI 10.17182/hepdata.30574

The production of very large transverse momentum hadron jets has been measured in the UA2 experiment at the CERN p p Collider for s = 540 GeV using a highly segmented calorimeter. The range of previously available cross sections for inclusive jet production is extended to p T = 150 GeV and the two-jet invariant mass distribution to m jj = 280 GeV with the largely increased data sample collected during the 1983 running period. The results are compared with the predictions of QCD models.

2 data tables

Table 1

LISTED ERRORS INCLUDE STATISTICAL AND THE PT-DEPENDENT UNCERTAINTIES. THE ADDITIONAL OVERALL SYSTEMATIC UNCERTAINTY IS 45PCT.

Table 2

LISTED ERRORS INCLUDE STATISTICAL AND THE M-DEPENDENT UNCERTAINTIES. THE ADDITIONAL OVERALL SYSTEMATIC UNCERTAINTY IS 45PCT.