Subprojekt C5: Multiloop-Calculations with Heavy Fermions in the SM and MSSM

Project leaders:
Prof. Dr. Matthias Steinhauser, Institute of Theoretical Particle Physics, Karlsruhe Institute of Technologie (KIT)
Dr. Luminita Mihaila, Institute of Theoretical Particle Physics, Karlsruhe Institute of Technologie (KIT)

In the project ``Multi-loop calculation with heavy fermions in the SM and MSSM'' physical quantities are considered where heavy fermions play a crucial role. We consider quantum corrections both in the Standard Model (SM) and its extension, the Minimal Supersymmetric Standard Model (MSSM).

One aspect of this project deals with quantum effects to rare decays of B mesons. In the current funding period a next-to-next-to-leading order (NNLO) prediction has been published. It has to be improved by incorporating results which only became available recently. Furthermore, the calculations within the MSSM also have to be extended to NNLO.

An approach has been developed to systematically compute higher order loop corrections within supersymmetric theories. First phenomenological results have already been obtained, e.g., the three-loop β function and the three-loop corrections to the Higgs boson mass in supersymmetric QCD. Currently the following problems are under consideration

  1. Yukawa corrections to the lightest Higgs boson mass;
  2. three-loop threshold corrections for αs and mb;
  3. threshold corrections at the GUT scale;
  4. supersymmetric corrections to the Higgs boson production and decay.
It is common to all topics that massive particles, in particular massive fermions, play an important role.

Last Change: 8th June 2011