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The Standard Model of particle physics collects all known elementary particles and their interactions into a unified framework. It explains all to-date non-gravitational phenomena that are observed in terrestrial experiments. However, today we know that the Standard Model is not complete. From astronomical and cosmological observations it is now evident and a hard fact that about 85% of the Universe’s present matter content is currently not understood. Moreover, many properties of the Standard Model itself, such as the mass of the Higgs particle are puzzling and poorly understood from a theoretical perspective.
New Physics beyond the Standard Model is a necessity and the experimental search as well as the exploration of theoretical possibilities for it is a center activity of modern particle physics. Our theory group participates in this process in a number of ways.
One focus of the group is on the exploration of the theoretical spectrum of ideas that concern the particle character of Dark Matter (DM). The most compelling solution to the Universe's missing mass problem is one in form of a yet undiscovered, fundamental particle of nature, DM. However, the concrete microscopic properties remain essentially unknown to date. In fact DM may comprise an entire hidden sector of particles, contain several states, new dark forces, and feature dark radiation components—with consequences for cosmology, for underground rare event searches, and at high-intensity particle accelerators such as the Large Hadron Collider (LHC). Our work is phenomenologically driven, i.e. we put a special emphasis on the testability of the proposed scenarios in particle physics experiment and astrophysical observation. Thereby we join a global effort that seeks to unravel the particle nature of the hidden sector, and to identify or to conclusively rule out candidates of Dark Matter. These efforts are led by J. Pradler.
A second focus of the group is on technical calculations that relate to experimental signatures of new physics at the LHC and at a possible future Linear Collider, in particular in connection with supersymmetry and with an extended set of Higgs particles. Symmetries have come to play a central role in the formulation of laws of nature. The most general symmetry of space-time is called supersymmetry. It is a symmetry between matter particles (fermions) and force particles (bosons) and it offers the possibility of embedding our today´s knowledge about the basic structure of matter into a larger, more general theory. It furthermore resolves a number of theoretical unpalatable issues of the Standard Model and much of the experimental efforts at LHC are driven by the search for these new symmetries. The theoretical activites on this are led by H. Eberl.