Theses Projects
The group focuses on exploring extensions of the Standard Model (SM) of particle physics to address fundamental open questions. Key research areas include extended Higgs sectors, searches for additional particles (e.g. extra gauge bosons, scalar leptoquarks, SUSY partners), and precision calculations within BSM extensions using perturbative methods such as NLO/NNLO corrections and consistent renormalisation schemes. The work also addresses the treatment of very heavy particles in phenomenological studies.
In the following we list concrete examples for topics that are of relevance. Working on them means to directly contribute to the research conducted in the group. You are always invited to contact us to discuss these and other possible topics you are interested in. If you are interested, please don’t hesitate to contact me at heidi.rzehak(at)physik.uni-freiburg.de.
Phenomenology in extended scalar sectors
Abstract: Study the Georgi–Machacek (GM) model, a scalar extension of the SM introducing two SU(2) Higgs triplets. The GM model can avoid large contributions to precision low-energy observables and can help explain small neutrino masses. Similarly, other extensions of the SM can be studied.
- Objectives: Test model predictions of observables with current experimental results; derive and/or study impact of higher-order corrections across the model parameter space.
- Methodology: Compute predictions in the considered model and compare with experiment (Python/Fortran/Mathematica).
- Literature: for e.g. the GM model: arxiv.org/pdf/1404.2640, arxiv.org/pdf/1709.03501
Dark Matter Candidates in a Model with an Extra Gauge Boson (DASM)
Abstract: The Dark Abelian Sector Model (DASM) extends the SM gauge group by an additional U(1), introducing an extra gauge boson, a Higgs singlet to generate its mass, and an additional neutral fermion. Possible dark matter candidates include the new gauge boson, a neutral Higgs boson, and the new fermion.
- Objectives: Investigate the viability of dark matter candidates, and optionally extend to cosmological/collider studies.
- Methodology: Compute predictions and compare with experiment.
- Literature: arXiv.org/pdf/2308.07845
Revisiting Perturbativity Bounds in the NMSSM
Abstract: We seek to construct extensions of the SM that are able to describe physics up to the largest energy scales. The energy-dependence of the couplings (such as e.g. of the strong force) plays a crucial role in this game. It was shown in the past that the requirement of perturbatively small couplings up to the Planck scale puts strong bounds on possible interactions of SM particles with yet undiscovered particles. Meanwhile LHC experiments are pushing the actual energy scale of said particles beyond the TeV scale in some scenarios.
- Objectives: Study how heavy BSM particles affect high-energy behaviour in the NMSSM context.
- Methodology: Solve coupled differential equations numerically with varying boundary conditions using tools like C, Fortran, Mathematica, Python.
- Literature: arxiv.org/pdf/0910.1785 (Chapter 3).
Vacuum Stability in the NMSSM
Abstract: The ground state of the theory describing nature should be stable on the scales of the lifetime of the universe. This requirement can put tight constraints on extensions of the SM scalar sector. SUSY adds one scalar degree of freedom for each Weyl fermion which leads to a multi-dimensional field space and an inherently complicated calculation of many tunneling rates. Similarly, other extensions of the SM can be studied.
- Methodology: Implement the NMSSM in the EVADE program to map vacuum-stable and -unstable regions in parameter space.
- Literature / Tools: arxiv.org/pdf/1812.04644 / gitlab.com/jonaswittbrodt/EVADE
