Calculation of higher order corrections for TeV colliders

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Our current understanding about the constituents of matter is summarized in the so-called Standard Model (SM) of Elementary Particle Physics. This model has been established and tested over the past decades at several high energy particle colliders around the world. However, one ingredient of this model, the Higgs boson, is still missing. Further, there are theoretical reasons to believe that the SM is only an effective theory at low energies of a more fundamental underlying theory behind. Candidates for such theories are supersymmetry, supergravity or string theories/theories with more than four space-time dimensions. To find the Higgs boson and to find out about a more fundamental theory, particle collisions at higher energies than in past experiments have to be investigated. To this aim, a Large Hadron Collider (LHC) is built at CERN (Geneva) where two protons are lead to collision, each having an energy which will be sufficient to produce Higgs bosons if the Standard Model assumptions are right. However, in order to extract such Higgs production events (called 'signals') from the huge amount of 'uninteresting' collisions (called 'background'), precise calculations and simulations of the signal as well as the background events are necessary. Such calculations are subject of the proposed research. In order to achieve the required precision and to simulate the experimental environment as close as possible, so-called 'radiative corrections' have to be calculated. Some techniques for such calculations already have been established over the last years, but only for a very limited class of processes, i.e. processes where only few particles in the final state are detected. For multi-particle production, the calculations are quite involved and require the development of new methods, largely based on powerful computer resources. Further, an international electron-positron Linear Collider is planned where measurements of an unseen precision at very high energy can be performed in order to learn more about the properties of the new particles which should be discovered at the LHC and to find particles which could not be detected so far.. In order to make theoretical predictions with a precision needed for such a machine, the calculation of radiative corrections has to be pushed even further. The proposed project will lead to a very precise theoretical prediction for a process where three so-called 'jets' are produced, which are clusters of particles bound together by strong interactions. This calculation will enable the measurement of the strong coupling constant with an unprecedented precision and also open the door to high precision predictions for other processes. In summary, the project aims at the construction of highly automated programs in order to make precise theoretical predictions for the wealth of data which will be produced at future high energy colliders.