Theoretical Particle Physics

Sebastian Jaeger

Note: The two projects below are indicative of a ‘top-down’, more theoretical and ‘bottom-up’, more phenomenological approach. These are complementary, and it is possible that over the course of a PhD project, both aspects may be touched upon.

Model-building for flavour near the TeV scale

The main consideration in constructing a successor to the Standard Model has long been the problem of stability (naturalness) of the electroweak scale, giving rise to the supersymmetry and composite Higgs paradigms. While the non-observation (so far) of the expected new particles is puzzling, there is increasingly compelling indirect evidence for new particles in the 1-10 TeV range in a number of precision, flavour-physics measurements, of a kind that is not generically expected in the standard paradigms. The aim of this project is to construct viable theoretical mechanisms that give rise to the observed effects, while addressing the naturalness problem and the absence of the signals usually associated with it, and explore possible connections with other phenomena (e.g., dark matter and evolution of the early universe).

Beyond the Standard Model at the intensity frontier: charting the course for discovery with flavour

Physics at the intensity frontier -- the precise study of symmetry-violating processes that are small or forbidden in the Standard Model -- has the potential to probe energy/mass scales that are well beyond the reach of direct search experiments. For example, it provides the strongest present constraints on supersymmetry and its breaking, and on strongly-coupled new physics models. Perhaps most excitingly, there are currently a number of apparent deviations from the Standard Model of particle physics in B- and K-physics measurements. The aim of this project is to make state-of-the-art predictions for new observables in B, K, top, and Higgs physics and confront these predictions with data. The outcome will be to characterise possible explanations of the current anomalies; to constrain and rule out candidate models; or, if new particles are discovered in direct searches, crucial ways for determining their couplings.