Higgs production and decay in models with extra singlets and doublets - Precise predictions forthe LHC

在大型强子对撞机上发现希格斯粒子是粒子物理学的巨大成功。下一步，必须精确测量这种粒子的性质，并且必须调查新的玻色子是否是标准模型的希格斯玻色子。这就需要研究扩展模型，并将它们与实验数据进行比较。一类有趣的扩展模型是那些具有额外的希格斯单态和双态的模型。这些模型符合精度测试，并且在去耦合极限上接近标准模型，即如果额外的希格斯玻色子的质量变大并且耦合被适当地选择。此外，它们允许对在大型强子对撞机上寻找的额外物理希格斯玻色子进行一致的描述。由于标准模型和这些扩展模型之间的差异可能很小，因此必须进行精确的理论预测，包括对次要顺序的修正。这些修正的计算需要高阶理论的一致表述，特别是重整化。这个项目的目的是研究用额外的希格斯单态或双态来扩展标准模型。我们将特别研究另外一个希格斯单重态或双重态的模型。我们将首先定义这些模型的完全重整化过程，并在次导数级显式地计算出重整化。然后，我们将对重要的希格斯产生和衰变过程进行评估，包括次前导阶强修正和弱电修正。最后，将结果应用到现有的蒙特卡罗程序中。由此产生的代码将提供给实验合作进行数据分析。

The discovery of a Higgs particle at the LHC was a spectacular success of particle physics. As next step the properties of this particle have to be measured precisely and it must be investigated whether the new boson is the Higgs boson of the Standard Model. This requires to study extended models and to compare them to experimental data. An interesting class of extended models are those with additional Higgs singlets and doublets. These models are in accordance with precision tests and approach the Standard Model in the decoupling limit, i.e. if the masses of the extra Higgs bosons get large and the couplings are chosen appropriately. Moreover, they allow for a consistent description of additional physical Higgs bosons which are searched for at the LHC. Since the differences between the Standard Model and these extended models might be small, precise theoretical predictions including corrections of next-to-leading order are mandatory. The calculation of these corrections requires a consistent formulation of these theories in higher orders and, in particular, a renormalization.This project aims at the investigation of Standard Model extensions with additional Higgs singlets or doublets. We will, in particular, study models with one additional Higgs singlet or doublet. We will first define the complete renormalization procedure of these models and work out the renormalization explicitly at next-to-leading order. Then, the important Higgs production and decay processes will be evaluated including next-to-leading-order strong and electroweak corrections. Finally, the results will be implemented into existing Monte Carlo programs. The resulting codes will be made available to the experimental collaborations for data analysis.