Radiative corrections to W+jet production at hadron colliders with a leptonic decay of the W boson

The production of W bosons and additional jets at hadron colliders is a topic of great phenomenological interest, because such processes have large cross sections and, owing to the clear decay signature of the W boson, can for instance be used to monitor and calibrate the collider's luminosity, as well as for a precise determination of the W-boson mass and width. Thus, a profound theoretical understanding of this process class is mandatory. In order to improve the accuracy of the theoretical predictions, this thesis is devoted to the calculation of the electroweak radiative corrections to the production of one W boson with one associated jet at the LHC and the Tevatron within the Standard Model. Since these corrections are at first evaluated on the parton level in a perturbative approach, we work in the parton model, where the hadronic cross section is obtained by folding the partonic contributions with the parton distribution functions that contain the non-perturbative information of the proton structure and have to be determined by experiment. We provide results for a stable W boson that is produced on its mass shell as well as for an intermediate (off-shell) W boson decaying into a charged lepton and a neutrino. For a consistent calculation of the next-to-leading order corrections, we have to take into account the virtual one-loop contributions, as well as the real bremsstrahlung corrections caused by radiation of one additional photon. Within both contributions, mass singularities appear that have to be treated with care within the numerical evaluation. In the calculation with a stable W boson in the final state, we use the method of phase-space slicing in order to exclude such singularities from the numerical phase-space integration and calculate them analytically in the problematic phase-space regions. For the off-shell calculation, however, we use the more sophisticated dipole subtraction technique to subtract the infrared-singular structures on the integrand level to allow for a stable numerical evaluation. Within this thesis, we extend this method to also enable the consistent treatment of non-collinear-safe observables related to photon radiation off muons. Additionally, the calculation of radiative corrections to processes involving an unstable W boson leads to the problem that a finite particle width has to be consistently introduced in the calculation. If this is done carelessly, gauge invariance might be destroyed even at the leading order of the perturbative series. Thus, we work in the complex-mass scheme to account for a proper inclusion of a finite W-boson width in our calculation. This particular scheme respects gauge invariance and can be applied in all phase-space regions. Our results are implemented into a flexible Monte Carlo code that allows for the calculation of total cross sections and differential distributions, where in principle any event-selection criteria that might be of physical interest can be applied. In the numerical analysis we observe large negative electroweak corrections at large transverse momenta that can be attributed to universal Sudakov logarithms. Moreover, relevant deviations in the shape of the transverse-mass distribution of the final-state lepton pair near the resonance are induced that are important with regard to a precise determination of the W mass. Thus, our code can provide crucial information as a tool for the analysis of LHC data. (orig.)