Theoretical investigations in preparation and for the next generation of measurements of the magnetic moment of the muon

• Applicant: Professor Dr. Dominik Stöckinger
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 264075790

The anomalous magnetic moment (g-2) of the muon is one of the most precisely calculated and measured quantities in elementary particle physics. Future, even more precise measurements will play an important, complementary role in analysing and interpreting physics beyond the Standard Model, which may be discovered at the Large Hadron Collider. In the course of an earlier DFG project, the Principal Investigator has contributed to the successful proposal for a new (g-2) experiment at Fermilab/USA, and in Germany he is the only member of the new (g-2) collaboration and reponsible particularly for the interpretation of the results in terms of physics beyond the Standard Model. Hence, the overarching goal of the project is to prepare this interpretation of possible future (g-2) measurements. For this purpose a broad research programme will be pursued. First, the precition of the prediction in important models (the Standard Model and its supersymmetric extension) will be increased by multiloop precision calculations, applying the developed expertise and infrastructure. Second, the predictions for (g-2) will be computed and compared in many alternative scenarios for physics beyond the Standard Model. The focus will not only be on standard supersymmetry, which has been studied comprehensively already. Rather, less well studied, but well motivated, qualitatively different scenarios within supersymmetry, and the Randall-Sundrum model with extra spacetime dimensions will be investigated. The aim is to identify which models allow significant contributions to (g-2) in the light of LHC-data. Third, we will investigate models in which no significant contributions to (g-2) are known. For these we will find the largest possible contributions or identity conditions under which significant contributions are possible. Finally, we will investigate two topics which contribute to a refinement of the Standard Model prediction. On the one hand, a contribution to the so-called hadronic light-by-light corrections will be computed. On the other hand, a recently increasingly discussed question will be considered: are the usually assumed relations between theory and experiment correct? The respective equations shall be checked and possibly corrected using insights and methods from quantum field theory, and the implications on the comparison theory--experiments shall be quantified.

• DFG Programme: Research Grants