Threshold resummation effects on the parton distribution function of the pion and time-reversal-odd single-spin asymmetries

By means of perturbative QCD an analysis of experimental data from different hadronic processes can be employed to extract so-called parton distribution functions, which parameterize the internal structure of hadrons. Several such analyses have been performed to determine the parton distributions of the proton to a very good accuracy. The same approach has also been used to uncover the internal structure of mesons, especially the pion. Most of the available information comes from Drell-Yan dimuon production. We perform a new analysis of pion Drell-Yan data including threshold-resummation effects in the calculation of the cross section. In contrast to all previous fixed-order analyses, the extracted valence parton distribution of the pion agrees with predictions based on the QCD parton model and perturbative QCD. Another topic studied in this thesis are single-spin asymmetries. In this thesis we calculate the leading perturbative contribution to the single longitudinal-spin asymmetry in semi-inclusive deep-inelastic scattering. (orig.)