Jeudi 17 Octobre 2024, 10:00 à IHP, Grisvard (314)	RENC-THEO (Rencontres Théoriciennes)	hep-th
Panos Betzios ( Ghent university )	An Inflationary Cosmology from Wormholes
Abstract:	In the context of inflationary cosmology a natural question arises on what precedes inflation itself. We review aspects of the Hartle-Hawking (no boundary) and Vilenkin (tunneling) proposals, and their relation to the Wheeler- DeWitt equation. These raise some paradoxes that are complementary in nature and in clash with observations. On the other hand theories of quantum gravity are better defined in the presence of a negative cosmological constant. I will propose a new type of wave function of the universe with asymptotically AdS boundary conditions in the far (Euclidean) past. In the semiclassical limit, it describes a Euclidean (half)-wormhole geometry with properties that result in an expanding universe upon analytic continuation to Lorentzian signature. In this context some of the aforementioned phenomenological issues can be resolved.

Jeudi 17 Octobre 2024, 11:45 à IHP, Grisvard (314)	RENC-THEO (Rencontres Théoriciennes)	hep-th
Fabiana De Cesare ( SISSA )	Exploring confinement in Anti-de Sitter space
Abstract:	Anti-de Sitter space acts as an infra-red cutoff for asymptotically free theories, allowing interpolation between a weakly-coupled small-sized regime and a strongly-coupled flat-space regime. I will discuss this interpolation in the context of Yang-Mills theories in AdS from the perspective of boundary conformal theories and its implications for the confinement/deconfinement transition. We find indications that at the transition a singlet scalar operator becomes marginal, destabilizing the deconfined phase existing at a small size and leading to a confined phase that smoothly connects to flat space.