Implementation and phenomenology of polarized cross sections in the simulation of vector boson production with the SHERPA event generator

Measurements of vector boson polarization in vector boson production processes offer the possibility to probe the concrete mechanism of electroweak symmetry breaking and the innermost gauge symmetry structure of the Standard Model. In addition, they are sensitive to effects of new physics beyond the Standard Model. Since massive vector bosons can only be observed as intermediate particles, polarized cross section templates from simulation are necessary to extract their polarization from measurable unpolarized distributions. The Monte-Carlo event generator SHERPA is not yet capable of simulating polarized cross sections. In this work, a new implementation allowing the simulation of polarized cross sections for vector boson production processes is presented and validated by comparison with literature data at fixed leading order. It will be released in SHERPA version 3.0.0. With this implementation, polarized cross sections of all possible polarization combinations for an arbitrary number of intermediate vector bosons can be simulated in a single simulation run by applying a spin-correlated narrow-width approximation. In addition, it is possible to directly predict the interference between different polarizations, and various polarization definitions can be studied. NLO QCD corrections on polarized cross sections of vector boson production processes can be approximately calculated, neglecting influences of virtual corrections on polarization fractions. First applications of the implementation demonstrate that differences of this approximation to full NLO QCD predictions are small. Merged calculations are another possibility to obtain NLO QCD polarization corrections which is also tested within this thesis. Furthermore, the influence of different polarization definitions on polarization fractions and polarized distributions of vector boson scattering processes at fixed leading order is studied.