We employ data taken by the JADE and OPAL experiments for an integrated QCD study in hadronic e+e- annihilations at c.m.s. energies ranging from 35 GeV through 189 GeV. The study is based on jet-multiplicity related observables. The observables are obtained to high jet resolution scales with the JADE, Durham, Cambridge and cone jet finders, and compared with the predictions of various QCD and Monte Carlo models. The strong coupling strength, alpha_s, is determined at each energy by fits of O(alpha_s^2) calculations, as well as matched O(alpha_s^2) and NLLA predictions, to the data. Matching schemes are compared, and the dependence of the results on the choice of the renormalization scale is investigated. The combination of the results using matched predictions gives alpha_s(MZ)=0.1187+{0.0034}-{0.0019}. The strong coupling is also obtained, at lower precision, from O(alpha_s^2) fits of the c.m.s. energy evolution of some of the observables. A qualitative comparison is made between the data and a recent MLLA prediction for mean jet multiplicities.
Overall result for ALPHAS at the Z0 mass from the combination of the ln R-matching results from the observables evolved using a three-loop running expression. The errors shown are total errors and contain all the statistics and systematics.
Weighted mean for ALPHAS at the Z0 mass determined from the energy evolutions of the mean values of the 2-jet cross sections obtained with the JADE and DURHAMschemes and the 3-jet fraction for the JADE, DURHAM and CAMBRIDGE schemes evaluted at a fixed YCUT.. The errors shown are total errors and contain all the statistics and systematics.
Combined results for ALPHA_S from fits of matched predicitions. The first systematic (DSYS) error is the experimental systematic, the second DSYS error isthe hadronization systematic and the third is the QCD scale error. The values of ALPHAS evolved to the Z0 mass using a three-loop evolution are also given.
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The production of collinear muon pairs has been studied using the JADE detector at thee+e− storage ring at PETRA. Results for the total cross section and the angular distribution were obtained at centre of mass (cm) energies ranging from 12 to 46 GeV. The data correspond to an integrated luminosity offLdt>90 pb−1, of which 71.2 pb−1 were taken at\(\left\langle {\sqrt s } \right\rangle \)=34.4 GeV and 17 pb−1 at\(\left\langle {\sqrt s } \right\rangle \)=42.4 GeV. The results are compared to electroweak theories, in particular the “Standard Model”.
QED comparison is to point like cross section.
Angular distributions - data requested from authors.
Forward-backward asymmetry calculated from a fit to the angular distribution of the form 1: + cos(theta)**2 + Bcos(theta).. Asymmetries quoted here are extrapolated to full solid angle. The asymmetry at sqrt(s) = 34.4 is -11.10 +- 1.75 +- 1.0 pct if the end-cap points are included.
The forward-backward charge asymmetry for the process e + e − → b b ̄ → μ ± + hadrons has been measured using the JADE detector at PETRA. An asymmetry of (−22.8 ± 6.0 ± 2.5)% was observed at an average center of mass energy of 34.6 GeV. For comparison, an asymmetry of −25.2% is expected on the basis of the standard Glashow-Salam-Weinberg model.
THE VALUE OF CONST HAVE BEEN RESCALED TO DEFINITION I3(Q) = 1/2 BY OPY.
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Energy-energy-correlations (EEC) have been measured with the JADE detector at c.m. energies of 14 GeV, 22 GeV and in the region 29 GeV<Ecm<36 GeV. Corrected results are presented of EEC and their asymmetry, which can be directly compared to theoretical predictions. At 〈Ecm〉=34 GeV a comparison with second order QCD predictions yields good agreement for the string model fragmentation resulting in a value of the strong coupling constant αs=0.165±0.01 (stat.). The independent fragmentation models, which yield values of αs between 0.10 and 0.15 depending on the treatment of energy and momentum conservation and of the gluon splitting, do not provide a satisfactory description of the data over the full angular range.
TABLES GIVEN HERE CONTAIN SELF CORRELATION. THIS IS SUBTRACTED IN THE FIGURE.
VALUE OF ASSYMETRY IN CORRELATIONS.
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RHO0 CROSS SECTION HAS BEEN EXTRAPOLATED OUTSIDE TO 0.1 < X < 0.7 RANGE.
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The inclusive production of D ∗± mesons in single tagged photon-photon collisions is investigated using the JADE detector at PETRA. D ∗± mesons are reconstructed through their decay into D 0 +π ± where the D 0 decays via D 0 →Kππ 0 . The event rate and topology are compared to the expectations of c quark production in the quark-parton model: γγ→c c .
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Total and differential cross sections for exclusive production of proton-antiproton pairs in photon-photon collisions have been measured using the JADE detector at PETRA. The total cross section in the CM angular |cos θ ∗ | < 0.6 reaches a maximum value of 3.8 nb for a γγ invariant mass of W γγ = 2.25 GeV, and decreases rapidly for higher values of W γγ . In the range 2.0 GeV < W γγ < 2.6 GeV the angular distribution is not isotopic. The nucleons are preferentially emitted at large angles to the collision axis.
Data read off graph.
Data read off graph.
The energy dependence of the relative production rate of three-jet events is studied in hadronic e + e − annihilation events at center of mass energies between 22 and 46.7 GeV. Three-jet events are defined by a jet finding algorithm which is closely related to the definition of resolvable jets used in O( α s 2 ) perturbative QCD calculations, where the relative production rate of three-jet events is roughly proportional to the size of the strong coupling strength. The production rates of three-jet events in the data decrease significantly with increasing centre of mass energy. The experimental rates, which are independent of fragmentation model calculations, can be directly compared to theoretically calculated jet production rates and are in good agreement with the QCD expectations of a running coupling strength. The hypothesis of an energy independent coupling constant can be excluded with a significance of four standard derivations.
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The production and decay of τ-pairs was studied with the JADE detector at PETRA at center-of-mass energies of 30 ⩽√ s ⩽ 46.78 GeV. The total production cross section for τ-pairs agreed with QED predictions to order α 3 . Lower limits on QED cut-off parameters of Λ + > 285 GeV and Λ − > 210 GeV at 95% confidence level were ontained. The decay branching fractions into one and three charged particles were determined to be (86.1 ± 0.5 ± 0.9)% and (13.6±0.5 ±0.80)%. In the angular distributions a forward-backward asymmetry was observed, from which the axial-vector weak charge to the τ was determined to be a τ = −0.74 ± 0.22 in agreement with the standard model. An analysis of the process e + e − → τ + τ − γ showed agreement with QED calculations to O(α 3 ).
Includes data from earlier analysis at lower energy - M. Nozaki - Tokyo - UTLICEPP-82-02.
Angular distributions - data requested from authors.
Forward-backward asymmetry determined from fit to angular distribution of form N*(1 + cos(theta)**2 + (3/8)*A*cos(theta)).
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