Precision calculations in QCD

At the upcoming Large Hadron Collider (LHC) at CERN, the most expensive and ambitious particle physics project ever, we hope to understand the origin and mechanism of electroweak symmetry breaking which is responsible for the masses of all observed particles. The measurements at the LHC might also shed light on other open questions of particle physics such as the origin of flavour, the composition of dark matter and the nature of dark energy, questions which might or might not be related to electroweak symmetry breaking. Based on theoretical arguments like naturalness and fine-tuning, we belief that the Standard Model (SM), the theory which currently is the cornerstone of our understanding of particle dynamics, is deemed to fail around the TeV scale, the energy regime which will be explored by the LHC. We expect therefore to discover signals of new physics at the LHC. These signals might manifest themselves as beautiful resonances or they might be well hidden behind large SM background processes. In order to fully exploit the discovery potential of the LHC and, in a subsequent stage, to match the precision measurements at upgrades of the LHC and at the International Linear Collider (ILC), it is vital to be able to compute both the signals and the background processes with best accuracy. The unifying theme of my research is to provide theoretical studies that can match both the current precision of running colliders, as well as the expected accuracy of upcoming experiments. Specifically, I am working at (i) improving the accuracy of the description of processes involving many particles in the final state that are relevant for the LHC, using general, semi-numerical methods, (ii) computing automatically the dominant corrections to semi-inclusive final state observables to derive new constraints on parton distribution functions, (iii) developing methods to exploit heavy-flavour tagging which is important for searches of new physics, and (iv) using effective theory methods to treat the finite width of unstable particles systematically to higher orders, thereby solving a long-standing problem in quantum field theory. In summary, my research aims at guaranteeing that the theoretical predictions will be of the highest possible standards, in order to match the formidable experimental effort at the LHC and ILC.