[IP2I seminar] F. Nortier (IP2I, Lyon) - UV/IR Mixing: Bridging the Graviton and the Higgs Boson

mardi 13 oct. 2026, 14:00 → 15:00 Europe/Paris

The hierarchy problem—specifically, the naturalness issue of how an elementary Higgs boson can be so light compared to the Planck scale—has been one of the major open questions in particle physics for nearly 50 years. It arises from the Wilsonian approach to effective theories, which relies on the decoupling of ultraviolet (UV) and infrared (IR) scales—the fundamental organizing principle of modern physics. Conventional symmetry-based solutions (such as supersymmetry) predict the existence of new particles near the electroweak scale that should have been discovered at the LHC; this discrepancy is known as the "little hierarchy problem." In this seminar, I will present the classic arguments suggesting that gravity—particularly through black hole physics—challenges the Wilsonian paradigm by introducing a mixing between UV and IR scales. I will then outline my research program at IP2I, which revisits the "classicalization" scenario; this approach seeks to reproduce a UV/IR mixing analogous to that of gravity through a scalar interaction, such as the one mediated by the Higgs boson. The result is a compromise between naturalness and consistency, which requires the existence of a "little hierarchy" between the mass of this scalar boson and a new strong-coupling scale, thereby offering a unique opportunity for future colliders.