Study of quantum chromodynamical effects in the total cross section of the electron positron annihilation into hadrons

This thesis is concerned with the annihilation of electrons and positrons into hadrons. The data which were obtained by the detector PLUTO at the storage ring PETRA at c.m. energies of 12 - 31.6 GeV are analyzed. In the whole energy range a constant slope of the total cross section with R=sigmasub(tot)/sigmasub(μμ)=4.06+-0.10(stat.) +-0.20 (syst.) is shown. This value prefers the QCD expectation with Rsub(QCD)=3.87 instead of the naive quark-parton model with Rsub(QPM)=3.67. The calculation of αsub(s) resulting from sigmasub(tot) yields regarding the anti Manti S renormalization scheme: αsub(s)=0.30+-0.06(stat.)+-0.14(syst.) and therefore an exclusion of the naive quark-parton model by 2 standard deviations (95% c.l.) at quadratic addition of statistical and systematic errors. In addition the energy distributions, the mean multiplicities, and the inclusive energy spectra both for the charged and for the neutral contributions of the hadronic events are studied. The comparison with a qanti qg Monte Carlo code shows a very good agreement between the data and the theoretical predictions. (HSI)