Tovrards the fate of our Universe: Uncovering the Global Structure of Scalar Potentials

• Applicant: Sebastian Biekötter
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2020 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 444759442

Fundamentally, one of the arguments why we exist and, more importantly, why we are still here is that there is more matter than anti-matter in the universe today. The reason for this imbalance, however, is still an unresolved mystery and arguably one of the most compelling questions in fundamental physics. From a particle physics point of view, the answer might be deeply related to the Higgs boson particle, which was originally introduced to give mass to any particle in our universe. Its experimental discovery at the Large Hadron Collider (LHC) at CERN has established the most successful theory of all known elementary particles, the so-called Standard Model of particle physics.Currently, most theoretical and experimental efforts are focussed on the precise determination of the properties of the Higgs boson at the LHC in order to improve our understanding of how elementary particles acquire their mass. However, some of its features that might lie at the heart of our very existence still elude all tests by the LHC experiments and therefore remain unknown. Most importantly, the LHC experiments cannot possibly measure the global shape of the so-called Higgs potential. Figuratively, the Higgs potential is a landscape with different hills and valleys, describing the amount of energy that can be stored at each point in space. Energies accessible at the LHC can only probe the Higgs potential locally, that is, in the vicinity of a valley. In my proposed research I aim to go beyond these valleys and explore possible ways to access the global structures of the Higgs potential, i.e. also the hills at high energies.In order to do so, I want to consider physical objects, ranging from subatomic to galactic scales, that are sensitive to the global features of the Higgs potential and predict their observable consequences. These objects can be new, hypothetical particles associated to the hills of the Higgs potential, that can be found at particle collider experiments. Intriguingly, this can also include modified gravitational wave signals, which are subject to detection by the recent advances in gravitational wave astronomy put forward by the LIGO experiment. I aim to bridge the gap between these observables that can probe the global shape of the Higgs potential and the local properties of the Higgs boson as determined by the LHC experiments. Therefore, with my research I expect to provide substantial theoretical as well as experimental guidance to drastically enhance the discovery potential for yet unknown physics phenomena that have eluded detection so far.Finally, the implications of my proposed research go far beyond the determination of the properties of the Higgs boson itself and can tremendously deepen our understanding of presumably one of the most fundamental questions about the abundance of matter in the universe that we observe today, i.e. about why we exist and why we are still here.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Professor Dr. Michael Spannowsky