Research: Physics Beyond the Standard Model

The discovery of the Higgs boson at the Large Hadron Collider (LHC) in 2012 formally completed the Standard Model of particle physics. However, there exist clear experimental evidences that demand physics beyond the Standard Model. The detection of neutrino oscillations which was awarded the physics Nobel Prize in 2015 and the resulting conclusion that neutrinos are massive particles was the first experimental confirmation of physics beyond the Standard Model. Further experimental evidence for physics beyond the Standard Model is the observed baryon asymmetry of the Universe. We do not observe sufficient anti-matter to balance the energy budget of the early Universe. Besides these clear experimental observations, there are further indications that the Standard Model is incomplete: the hierarchy problem, the flavour puzzle, the strong CP problem, the stability of the proton, inflation, dark matter, and dark energy.

Taking into account latest international experimental results such as the observation of gravitational waves and in collaboration with local experimental searches for dark matter, lepton number violation, additional neutrinos, and new neutrino interactions, the theory group of the division explores extensions of the Standard Model of particle physics. Extending the Standard Model requires expertise in rather different fields to connect theoretical concepts to experimental insights. Interesting topics discussed by the group are for example electroweak symmetry breaking, conformal extensions of the Standard Model, phenomenological studies and new models to describe Dark Matter, Grand Unified Theories, extra dimensions, lepton flavour violation, lepton number violation, baryon number conservation, sterile neutrinos, left-right symmetric extensions of the Standard Model, Dark Energy, models of inflation, new theories of gravity, gravitational waves as probes for new physics, neutrino masses and mixings as well as baryogenesis.

Fig. 1: Particles of the Standard Model. The origin of three generations of fermions (I,II,III) is not understood. Theoretical arguments and experimental observations require extensions.