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

介子的反常磁矩（g-2）是基本粒子物理学中最精确计算和测量的量之一。未来，更精确的测量将在分析和解释标准模型之外的物理方面发挥重要的补充作用，标准模型可能会在大型强子对撞机上被发现。在早期DFG项目的过程中，首席研究员为美国费米实验室的新（g-2）实验的成功提议做出了贡献，在德国，他是新（g-2）合作的唯一成员，并特别负责从标准模型之外的物理角度解释结果。因此，该项目的首要目标是准备对可能的未来（g-2）测量的解释。为此目的，将推行一项广泛的研究方案。首先，重要模型（标准模型及其超对称扩展）的预测精度将通过应用已开发的专业知识和基础设施进行多环精度计算来提高。其次，对（g-2）的预测将在标准模型之外的许多其他物理场景中进行计算和比较。重点将不仅仅是标准超对称，这已经得到了全面的研究。更确切地说，研究得不太好，但动机很好，在超对称和Randall-Sundrum模型中有额外时空维度的定性不同的场景将被调查。其目的是根据大型强子对撞机的数据确定哪些模式可以对（g-2）作出重大贡献。第三，我们将研究对（g-2）没有显著贡献的模型。对于这些，我们将找到可能的最大贡献或可能产生重大贡献的身份条件。最后，我们将探讨有助于改进标准模型预测的两个主题。一方面，对所谓强子光对光修正的贡献将被计算。另一方面，一个最近讨论得越来越多的问题将被考虑：通常假设的理论和实验之间的关系是否正确？应使用量子场论的见解和方法检查并可能纠正各自的方程，并对比较理论-实验的含义进行量化。

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.