Theoretical Particle Physics

One of the great successes of twentieth century physics was that all the forces in nature, however diverse they might appear, were reduced to only four fundamental interactions. Three of those, the electro-magnetic, the weak and the strong forces, are very well understood. Together they constitute what is known as the Standard Model of particle physics - whose final verification was achieved with the discovery of the Brout-Englert-Higgs particle at CERN in 2012. The force which is most familiar to us, the gravitational force, is also the least understood one! Thanks to Einstein, we do have a very good classical description of gravity: the theory of general relativity. While it works very well at larger distances, we expect that quantum mechanical effects come into play when studying gravity at tiny scales. However, general relativity and quantum mechanics turn out to be hard to reconcile. So then a fundamental question is what is the quantum theory of gravity? Answering this question is essential in order to tackle some of the biggest puzzles in physics, related to black holes and the big bang. The leading proposal for a theory of quantum gravity is string theory (links to introductions to string theory can be found below).

The VUB Theoretical High Energy Physics group was founded in 1995. Originally it was focused on the more formal aspects of string theory and supersymmetric field theories, which remains a key research direction of the group. In recent years the group has put a particular effort in developing lines of research which would connect more formal ideas with experiments and observations. One way to do this is via cosmology, which since many years has been an important research topic. A second approach is concerned with the search for physics beyond the standard model at accelerators, in particular the LHC. This line of research has been initiated in 2010 in close collaboration with the experimental high energy physics group at the VUB. A third way to make contact with experiments is via applications of holography to strongly coupled physical systems, the canonical example being the study of the formation and the behavior of the quark-gluon plasma in heavy ion collisions (at RHIC and at the LHC).