TASSO results on e+e- annihilation between 13 and 31.6 GEV and evidence for three jet events

Hadron production by e+eannihilation was analyzed for c.m. energies from 13 up to 31.6 GeV at PETRA. Results are reported on R and on gross features of the final states such as multiplicity and inclusive momentum spectra. No evidence was found for a contribution of the top quark. Jet formation was studied in detail. The transverse momentum of hadrons relative to the jet axis was found to increase strongly with c.m. energy. The broadening of the jets is not uniform in the azimuthal angle around the jet axis but tends to yield planar events with large and growing transverse momenta in the plane and small transverse momenta normal to the plane. The simple q anti q jet picture is ruled out. The observation of planar events shows that there are three basic constituents which turn into hadron jets. Indeed, several events with three well separated jets of hadrons were observed at the highest energies. The data can be naturally understood in terms of hard gluon bremsstrahlung, with the quarks and gluons fragmenting into hadrons with limited transverse momenta. (orig.)