Ah Ball

EXPERIMENTAL-STUDY OF JETS IN ELECTRON-POSITRON ANNIHILATION

Abstract Data on hadron production by e + e − -annihilation at c.m. energies between 30 GeV and 36 GeV are presented and compared with two models both based on first-order QCD but using different schemes for the fragmentation of quarks and gluons into hadrons. In one model the fragmentation proceeds along the parton momenta, in the other along the colour-anticolour axes. The data are reproduced better by fragmentation along the colour axes.

Test of Quantum Electrodynamics at {PETRA}

Differential cross sections for the reactions e+e− → e+e− and e+e− → γγ are given for energies between 27.7 and 31.6 GeV. The results agree with the predictions of standard quantum electrodynamics and set lower limits to the usual cut-off parameters of up to 104 GeV. A limit on the Weinberg angle, sin2θW < 0.63, is obtained at unprecedentedly high q2.

A measurement of the electroweak induced charge asymmetry in e+e−→bb̄☆

Abstract 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.

Experimental evidence for differences in 〈p⊥〉 between quark jets and gluon jets

Abstract We want to dedicate this work to our friend Peter Dittman who contributed so much to the JADE experiment and who died on 31.8.1982.

BARYON PRODUCTION IN E+E(-)-ANNIHILATION AT PETRA

Abstract Data on p and Λ production by e + e − -annihilation at CM energies between 30 and 36 GeV are presented. Indication for an angular anticorrelation in events with baryon-antibaryon pairs is seen.

PRECISE MEASUREMENT OF TOTAL CROSS SECTIONS FOR THE PROCESS e+e - ~ MULTIHADRONS IN THE CM ENERGY RANGE BETWEEN 12.0 AND 36.4 GeV

The total cross section for the process e+e− → hadrons has been measured in the CM energy range between 12.0 and 36.4 GeV using the JADE detector with a typical systematic error of ±3%. The ratio is found to be constant over this range with an average value of 3.97 ± 0.05 (statistical and point-to-point systematic error) ± 0.10 (normalization error). The data were compared with the standard electro-weak interaction model including QCD corrections.

Observation of a charge asymmetry in e+e− → μ+μ−

The angular distribution and the s dependence of the total cross section for the process e+e− → μ+μ− have been measured using the JADE detector at PETRA. After radiative corrections, a forward-backward asymmetry of −(11.8±3.8) % was observed at an average centre of mass energy of 33.5 GeV. For comparison, an asymmetry of −7.8 % is expected on the basis of the standard Glashow-Salam-Weinberg model.

UPPER LIMIT ON BEAUTY LIFETIME AND LOWER LIMIT ON WEAK MIXING ANGLES

Abstract Muons from a multihadron sample are used to determine an upper limit τ −12 s (95% CL) on the lifetime of beauty particles. The data are obtained with the JADE detector at PETRA. The result is interpreted within the standard model.

Test of Fragmentation Models by Comparison with Three Jet Events Produced in e+ e- ---> Hadrons

Abstract The energy flow and particle flow distributions of planar three-jet events produced in e+e−→ hadrons at CM energies between 29.5 and 36.4 GeV have been interpreted in terms of the reactions e+e−→q q g and compared with the distributions calculated from two different fragmentation schemes, one based on independent parton fragmentation, the other one on fragmentation along colour flux lines. The particle density at angles between the two highest energy jets is found to decrease more strongly with increasing transverse mass of the particles than the particle density at angles between any of these jets and the lowest energy jet. The high momentum particles within the two most energetic jets are emitted at larger angles with respect to the lowest energy jet than the average particles. These observations are well reproduced by fragmentation along colour flux lines, but not by independent parton fragmentation.

Measurement of the processese+e−→e+e− ande+e−→γγ at PETRA

AbstractCross sections for the reactionse+e−→e+e− (Bhabha scattering) ande+e−→γγ are measured for center-of-mass (c.m.) energies