Eductions of Edge Mode Effects

Abstract: Edge modes in gauge theories, whose raison d'etre is in the nature of the test functions used for imposing the Gauss law, have implications in many physical contexts. I discuss two such cases: 1) how edge modes are related to the interface term in the BFK formula and how they generate the so-called contact term for entanglement entropy in gauge theories, 2) how they describe the dynamics of particles in generalizing the Einstein-Infeld-Hoffmann approach to particle dynamics in theories of gravity.