Results from the JADE Collaboration

Results from the JADE experiment at PETRA in the energy range between 27.7 and 35.8 GeV are reported. QED is tested using the reactions $e+e− ⇒ e+e−, μ+μ−, γγ$ and lower limits on hypothetical cut‐off parameters of up to 100 GeV are obtained. Predictions of the standard electro‐weak theory are compared with the data and limits are derived on the values of the vector and axial vector coupling constants. Extended gauge models containing more than one neutral weak boson are also tested and lower limits are placed on the masses of such bosons.

For the reaction $e+e− ⇒ hadrons$ topological distributions of the hadrons are studied. At s√ of about 30 GeV it is shown in a model independent way that the observed planar events actually possess three‐jet structure strongly suggesting gluon bremsstrahlung as the origin of these events. By comparison of the data with the qqg — model we obtain a value for the strong coupling constant of $αs (q2) = 0.17 ± 0.02 ± 0.05$⁠.

At the highest energy of about 35 GeV a search for new flavour production is performed. An average value of $R = 3.9 ± 0.2$ is obtained, compatible with the production of quarks with only the known flavours (u, d, s, c, b). Also the study of the topological distribution of the final state hadrons at this energy shows no evidence for new flavour production.

In the energy range between 12 and 35 GeV a measurement of the neutral energy fraction in multihadronic events is reported. Free quarks with charge $Q = 2/3$ are searched for and upper limits for the production have been derived from dE/dx measurements which are of the order of $0.01· σμμ$⁠. An upper limit of the lifetime of B‐mesons of about $2 · 10−9s$ is obtained.