On the Treatment of Colour-Charged Resonances in Precision Calculations of Monte Carlo Generators

This thesis aims at improving theory predictions of particle collisions at the Large Hadron Collider. More specifically it introduces new algorithms for Monte-Carlo event generators, like SHERPA , which are used to simulate the measurements performed at such colliders. In calculating the process of collisions beyond the leading order in perturbation theory, the concept of subtraction schemes and parton showers, is indispensable. However, both of these concepts experience problems if the process in question features intermediate, unstable particles. In particular neither SHERPA's subtraction algorithm nor its showers provide a solution to that issue. To overcome those problems we devise a new subtraction scheme which is based on the use of so-called pseudo-dipoles. In addition we discuss the construction of a resonance-aware shower. To validate and test our findings, we have implemented the new algorithms within SHERPA. A thorough comparison of the newly found results with the established simulations concludes this thesis.