The goal of High Energy Theory research at EPFL is to shed light on the basic mysteries in physics. These are the origin of mass scales (weak scale, vacuum energy density), the origin of flavor, the structure of fundamental forces and their possible unification, the content of the universe (the nature of dark matter, the origin of matter-antimatter asymmetry) and the origin of Big Bang. While that is perhaps too ambitious a goal, we are luckily entering an era where crucial data will be collected in both the lab and the cosmos. Those data will likely help us unveil some of the above mysteries and possibly reshape our formulation of the others.

### The following groups are part of HET@EPFL

LPPC is working on the interplay between particle physics and Cosmology. Cosmology provides the key evidence that the canonical Standard Model (SM) of particle physics, although extremely successful in explaining existing accelerator data, is not a complete theory of Nature. In particular, it contradicts to the observed neutrino oscillations, does not provide a dark matter (DM) candidate, and gives no explanation for the observed excess of matter over anti-matter in the Universe. It also does not explain the present accelerated expansion of the Universe, and does not lead to primordial inflation. We take these facts as a guiding principle for the quest for a fundamental theory. Other directions of research of LPPC include various approaches to effective quantum theory of gravity, to the strong CP problem, the role of quantum anomalies in physics, phase transitions in gauge theories at high temperatures and their cosmological applications, model independent study of Dark Matter and structure formation in the Universe, the search for decaying Dark Matter.

LPTP focusses on the open problems in our present understanding of fundamental physics. A grand goal is to unveil a more fundamental description behind the Standard Model of particle physics, one which could at the same time overcome its shortcomings and explain its remarkable structural features. Electroweak symmetry breaking, flavor and the unification of forces are aspects of major concern. Another major direction of exploration is tied to cosmological evolution, and find its clues in the Big Bang, in present day accelerated expansion and in the mystery of Dark Matter. LPTP approaches the above grand questions both through a broad structural exploration of Quantum Field Theory and through careful consideration of the available data. In particular, we eagerly await the data from the next run of the Large Hadron Collider.

The Fields and Strings Laboratory develops research in the context of Quantum Field Theory (QFT) and String Theory. QFT is the mathematical framework that describes Particle Physics and long distance phenomena in Condensed Matter. However, our understanding of QFT is still rather incomplete when interactions are strong. The FSL develops new non-perturbative methods to study QFT. In particular, the conformal bootstrap approach is a central tool in our research activities. One of our concrete goals is to map out the space of (conformal) field theories with a few low dimension operators. Another reason to study QFT is the gauge/gravity duality. This allows us to translate questions about quantum gravity into QFT. We explore the gauge/gravity duality to investigate questions like the quantum dynamics of black holes and the emergence of spacetime locality.

My research group concentrates on the study of scale invariant systems. These play a major role in theoretical physics, connecting critical phenomena in condensed matter to theories of quantum gravity and particle physics and their description is elegantly captured by the formalism of Conformal Field Theories (CFTs). Our group aims to explore new directions and push forward the frontiers of the conformal bootstrap, both on the numerical and analytic side, with the ultimate objective of a detailed classification and understanding of scale invariant systems and their properties.

### Scientists/Lecturers

The research of my group focuses on the study of the fundamental interactions among particles. The Standard Model (SM) of particle physics gives a successful description of high-energy processes but leaves many questions unanswered, like the origin of the electroweak symmetry breaking or the nature of the Dark Matter in the Universe. Finding an extension of the SM and a solution to these puzzles is the ultimate goal guiding our work. We are interested both in the construction of new models and in the investigation of their phenomenological consequences. An important role in this sense is played by physics at current and future colliders. Searches for new particles and a precise determination of the properties of the newly-discovered Higgs boson give powerful probes of new physics and are among the topics studied by our group.

The research of my group (Sergey Sibiryakov, Mikhail Ivanov) is centered around open problems in gravitational physics and cosmology. General relativity (GR), which identifies gravity with space-time geometry, has been remarkably successful in explaining gravitational phenomena in many regimes from table-top experiments to astrophysics. However, combined with the principles of quantum mechanics (QM), GR is doomed to fail at extremely short distances, where it must be substituted by a more fundamental description. This raises many fascinating questions shaping our research: What are the key features of quantum gravity? How they are related to the principles of GR and QM? What are implications of quantum gravity for the physics of other fundamental forces? Though far beyond the reach of present Earth-based experiments, quantum gravity may be testable through its influence on the first instances of the life of the universe. Rapid progress in cosmological observations during recent years has provided first precision data about this epoch and the amount of information is expected to greatly increase in the near future. However, precise knowledge of the evolution of the universe at late times is required to properly decipher this information. In our work we aim to advance the understanding of the late-time universe and shed light on the properties of dark matter and dark energy