The following Master’s projects are currently being offered by members of our group:

Probing Fundamental Physics with Gravitational Waves

The recent detection of gravitational waves by the LIGO collaboration marks the dawn of a new era of gravitational wave astronomy and precision tests of gravity. In this thesis, the student will explore what can be learned about the fundamental laws of physics from future gravitational wave observations. In other words, how can physics beyond standard model (of both particle physics and gravity) manifest itself in the gravitational wave signals? The nature of the project will be exploratory, so the precise research direction will be developed in collaboration with the supervisor and is expected to evolve over time. The thesis will require a strong background in theoretical physics, especially in quantum field theory and general relativity.

Supervisor: Daniel Baumann

**Searching for New Physics with Cosmological Observations**

*Description to appear.*

Supervisor: Daniel Baumann

Cosmological Constraints from Quantum Gravity and Their Consequences

Cosmological observations might very well be our only probe of quantum gravity. As a consequence it is of crucial interest to determine the potential limitations on effective field theory descriptions of primordial cosmology in general and de Sitter or inflationary vacua in particular. The origin of these limitations could range from dynamical effects due to the presence of cosmological horizons, to selection effects due to specific boundary conditions. This can either be addressed from the bottom-up, based on general and sometimes phenomenological expectations, or from the top-down using ingredients from string theory. At the very least this should make (inflationary) cosmology more predictive, and in addition carries the promise of providing a (indirect) probe of quantum gravity. The details of a research project in this direction will be determined along the way, depending on the interest and development of the student.

Supervisor: Jan-Pieter van der Schaar

**Higgs Cosmology**

The Higgs boson is a special particle in the Standard Model (SM), as it is responsible for the breaking of the electroweak symmetry, as well as for providing mass to the quarks and leptons. Many processes in the early universe — e.g. inflation and phase transitions — are described in terms of (effective) scalar fields. As the Higgs is the only scalar field in the SM, it is natural to ask whether it can play a special role in cosmology as well. There are many aspects to Higgs cosmology; the direction of the research project will be determined together with the student. Two possible avenues are:

*Electroweak baryogenesis.*The matter- antimatter asymmetry of the universe may be created during the electroweak phase transition. Such a scenario has the added benefit that it may be tested by the LHC and/or other experiments.

*Higgs inflation and reheating.*In models where the Higgs field is responsible for inflation, the process of reheating — how at the end of inflation all energy is transferred from the Higgs field to the thermal bath of SM particles — can be studied in a concrete setting, as all couplings are known.

Supervisor: Marieke Postma

**Explorations in Quantum Gravity**

I typically develop masters projects in collaboration with students, so feel free to come with your own ideas for projects. Some suggestions I can make:

*Quantum teleportation.*What does it feel like to be quantum teleported? This doesn’t sound like a very scientific question, but it was the subject of a fascinating recent paper by Maldacena, Stanford, and Yang. The project would be to understand various aspects of the physics of black holes, wormholes, and quantum teleportation.

*Gravitational instability of Anti-de Sitter spacetime.*I have been trying to understand under what circumstances matter coupled to classical gravity in Anti-de Sitter spacetime is unstable to gravitational collapse (one review article is https://arxiv.org/abs/1312.5544). I have an extremely boring possible Master’s project that would lead to calculating some interaction coefficients that are important in this problem. This project will involve tedious but tractable quantum field theory calculations, and hopefully lead to a published paper, but I do not expect it to be the most intellectually exciting project.

*Weak gravity conjecture and vacuum decay.*I claimed in a recent paper that all solutions in string theory can decay to a lower energy state. Is this claim true? Can it be supported by calculations?

Supervisor: Ben Freivogel