Theoretical high energy physics describes the interactions and the propagation of elementary particles such as electrons, neutrinos and quarks, protons' and neutrons' constituents. Due to the "smallness" of these particles, classical physics laws cannot be applied to describe them: one should use instead the concepts of quantum mechanics and relativity.
Nowadays, to describe these interactions, we use Quantum Field Theory. The Standard Model of electroweak and strong interactions, proposed in the 70s and tested at the permill precision, is based on the principles of this theory. Recently, this model has received one final spectacular validation from the discovery of the Higgs boson at CERN in Geneva.
There are, however, several experimental observations (neutrino masses, dark matter, accelerated expansion of the universe) which cannot be explained in the framework of the Standard Model. Moreover, a number of important unresolved theoretical issues (the failure of the Standard Model to account for gravity, the hierarchy problem, the strong CP problem, etc.) all seem to indicate that the Standard Model is an incomplete theory and that it therefore must be extended.
Many possible modifications to the Standard Model have been and are currently being actively studied by high energy theoretical physicists; these range from simple Standard Model variants to radically new theories, like String Theory. In all these physical models of fundamental interactions, Quantum Field Theory plays a central role; moreover, it can also be usefully applied to other domains of physics, such as condensed matter. The study of Quantum Field Theory, which aims both to develop new effective computational methods and to deepen our understanding of its mathematical structure, is therefore essential for advancing the theory of fundamental interactions.
In our Department we work in different domains of Theoretical High Energy Physics: