NLO Corrections and Parton Showers in the LHC Era

The Large Hadron Collider provides a challenging environment, not only for experimentalists. Precise predictions are needed in order to use its potential to full capacity. This thesis focuses on predictions including higher-order corrections in a twofold way. Both results for a pure parton level calculation and for a calculation incorporating a parton shower are presented. Higgs boson plus photon production via vector boson fusion was implemented in a fully flexible parton-level Monte-Carlo program. The results at next-to-leading order accuracy are discussed. It is found that the corrections are large in some regions of phase space. For the simulation of a parton shower matched to a next-to-leading order matrix element, a mixed-language runtime interface was established to use existing matrix elements for Higgs boson production via vector boson fusion. Results are discussed for different parton shower algorithms and matching schemes. The simulation is shown to have a substantial dependence on the shower algorithm and matching scheme in some of the examined observables. This indicates a significant systematical uncertainty in such calculations.