Alladi Ramakrishnan Hall

Residual gauge symmetries in Dirac's front form

Sucheta Majumdar

ENS, Lyon

Of the three forms of relativistic dynamics proposed by Dirac, the front
form offers a unique framework for studying symmetries of null
hypersurfaces. The goal of this talk is to discuss residual gauge
symmetries in electromagnetism and gravity in Dirac's front form. Working
in the light-cone gauge, I will demonstrate how the large gauge
transformations and BMS supertranslations may be obtained from residual
gauge invariance of the Hamiltonian action. The residual gauge symmetries
in the front form share some striking similarities with the asymptotic
symmetries found in the conventional (3+1) Hamiltonian or instant form
approach. I will illustrate how the the zero modes play a crucial role in
the front form, akin to boundary degrees of freedom in the asymptotic
analysis at spatial infinity.