Gauge theories and boundaries: from superselection to soft modes and memory

          @misc{ scivideos_PIRSA:24100139,
            doi = {10.48660/24100139},
            url = {https://pirsa.org/24100139},
            author = {Riello, Aldo},
            keywords = {Quantum Gravity},
            language = {en},
            title = {Gauge theories and boundaries: from superselection to soft modes and memory},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2024},
            month = {oct},
            note = {PIRSA:24100139 see, \url{https://scivideos.org/index.php/pirsa/24100139}}
          }
          

Abstract

I present an overview of the work I have done over the last few years on the phase space structure of gauge theories in the presence of boundaries. Starting with primers on the covariant phase space and symplectic reduction, I then explain how their generalization when boundaries are present fits into the reduction-by-stages framework. This leads me to introduce the concept of (classical) superselection sectors, whose physical meaning is clarified by a gluing theorem. Applying the framework developed this far to a null hypersurface, I then discuss how the extension of the Ashtekar-Streubel symplectic structure by soft modes emerges naturally, and how electric memory ties to superselection. If time allows, and depending on the audience’s interests, I will finally compare reduction-by-stages with the edge-mode formalism or discuss its relation to dressings and “gauge reference frames”. An overarching theme will be the nonlocal nature of gauge theories. This seminar is based on work done with Gomes and Schiavina.   References: The general framework: 2207.00568 Null Yang-Mills: 2303.03531 Gluing: 1910.04222 A pedagogical introduction: 2104.10182 Dressings and reference frames: 1808.02074, 2010.15894, 1608.08226