Exploring the Flavour Structures of Supersymmetric Models

The main goal of the present project is the theoretical analysis of the production of supersymmetric particles at future colliders and the determination of their main parameters. Supersymmetry is at present the most prominent extention of the Standard Model. The reasons for that are mainly theoretical: With supersymmetry we can better achieve the unification of the strong, electromagnetic and weak interactions between fundamental particles. Furthermore, supersymmetry allows us to keep the mass of the Higgs boson stable against quantum corrections. CP violation and flavour violation are two other phenomena which are not completely understood. There are two remarkable deviations of the theoretical predictions of the Standard Model from experimental data related to these phenomena. Firstly, the small amount of CP violation of the Standard Model is not sufficient to explain the observed baryon asymmetry of the universe. On the other hand, supersymmetric extentions of the Standard Model can provid additional sources of CP violation. This is another reason why supersymmetry is attractive. Secondly, recent experimental results on neutrino oscillation have established that neutrinos are massive particles, whereas the Standard Model implies that they are massless. These observations have stimulated growing interest in the phenomenon of lepton flavour violation, both from the experimental as well as from the theoretical side. The reason is because this phenomenon may open a window to physics beyond the Standard Model, whose contributions to lepton flavour violating processes are well below the current experimental upper bounds, which is mainly a consequence of loop suppression. In supersymmetric processes, however, an effect of lepton flavour violation can already occur at tree level. As a consequence, the phenomenon of lepton flavour violation could be accessible at future collider experiments. The experimental search for supersymmetric particles has, therefore, a high priority at all present and future accelerators. If supersymmetric particles are discovered, the next important goal will be the determination of their main parameters like masses, couplings etc. Among others the determination of their flavour violating as well as CP violating parameters will be very important. In order to facilitate the experimental searches as well as the determination of the supersymmetry parameters, many theoretical analyses have to be carried out. In the present project we will study how the supersymmetry parameters, in particular those responsible for flavour violation and CP violation, can be determined from future experimental data. For definiteness, we will consider supersymmetric particle production at the `Large Hadron Collider` LHC at CERN and a future electron-positron collider as the International Linear Collider ILC. We want to add that in the past years we were the only group in Austria working in this field that successfully participated in international collaborations. We made substantial contributions to clarify the problem how supersymmetric particles can be discovered. In our study we also want to treat some problems which came up in recent international workshops and which we want to clarify. We want to achieve the following goals: 1) We will work out which are the most suitable observables to identify an effect of flavour violation and CP violation, and determine the parameters responsible for these effects. 2) We will analyze the predictions of various supersymmetric models for flavour violating observables, in particular also for observables measured in B-physics. 3) We will study R-parity violating decays of supersymmetric particles and calculate their decay widths.

The main goal of the present project is the theoretical analysis of the production of supersymmetric particles at future colliders and the determination of their main parameters. Supersymmetry is at present the most prominent extention of the Standard Model. The reasons for that are mainly theoretical: With supersymmetry we can better achieve the unification of the strong, electromagnetic and weak interactions between fundamental particles. Furthermore, supersymmetry allows us to keep the mass of the Higgs boson stable against quantum corrections. CP violation and flavour violation are two other phenomena which are not completely understood. There are two remarkable deviations of the theoretical predictions of the Standard Model from experimental data related to these phenomena. Firstly, the small amount of CP violation of the Standard Model is not sufficient to explain the observed baryon asymmetry of the universe. On the other hand, supersymmetric extentions of the Standard Model can provid additional sources of CP violation. This is another reason why supersymmetry is attractive. Secondly, recent experimental results on neutrino oscillation have established that neutrinos are massive particles, whereas the Standard Model implies that they are massless. These observations have stimulated growing interest in the phenomenon of lepton flavour violation, both from the experimental as well as from the theoretical side. The reason is because this phenomenon may open a window to physics beyond the Standard Model, whose contributions to lepton flavour violating processes are well below the current experimental upper bounds, which is mainly a consequence of loop suppression. In supersymmetric processes, however, an effect of lepton flavour violation can already occur at tree level. As a consequence, the phenomenon of lepton flavour violation could be accessible at future collider experiments. The experimental search for supersymmetric particles has, therefore, a high priority at all present and future accelerators. If supersymmetric particles are discovered, the next important goal will be the determination of their main parameters like masses, couplings etc. Among others the determination of their flavour violating as well as CP violating parameters will be very important. In order to facilitate the experimental searches as well as the determination of the supersymmetry parameters, many theoretical analyses have to be carried out. In the present project we will study how the supersymmetry parameters, in particular those responsible for flavour violation and CP violation, can be determined from future experimental data. For definiteness, we will consider supersymmetric particle production at the `Large Hadron Collider` LHC at CERN and a future electron-positron collider as the International Linear Collider ILC. We want to add that in the past years we were the only group in Austria working in this field that successfully participated in international collaborations. We made substantial contributions to clarify the problem how supersymmetric particles can be discovered. In our study we also want to treat some problems which came up in recent international workshops and which we want to clarify. We want to achieve the following goals: 1. We will work out which are the most suitable observables to identify an effect of flavour violation and CP violation, and determine the parameters responsible for these effects. 2. We will analyze the predictions of various supersymmetric models for flavour violating observables, in particular also for observables measured in B-physics. 3. We will study R-parity violating decays of supersymmetric particles and calculate their decay widths.