Séminaire de Physique ThéoriqueEdge modes in gauge theory and gravity
Marc Geiller (Perimeter Institute, Canada)
Thursday 07 December 2017 14:00 - Tours - Salle 1180 (Bât E2)
Although the physical relevance of edge modes (or boundary degrees of freedom) has been appreciated for a long time, for example in condensed matter and 3d gravity, there is still no general and unified framework for understanding their appearance, their dynamics, and their possible physical implications. In this talk we will show that a proper understanding of gauge transformations in local spatial regions with boundaries requires the construction of an extended phase space containing extra edge mode fields. After motivating why this extension of the phase space is necessary both in classical and quantum theories, we will walk successively through the examples of theories having Abelian, non-Abelian, and diffeomorphism gauge symmetry. We will finish by discussing the relevance of this construction for the study of entanglement and quantum gravity in finite regions.