HET- seminar: Poulami Nandi

Speaker:  Poulami Nandi

Title: Conformal Carrollian Field Theories on Null Manifolds

Abstract: Conformal Carrollian groups are known to be isomorphic to Bondi-Metzner-Sachs (BMS) groups that arise as the asymptotic symmetries at the null boundary of Minkowski spacetime. The Carrollian algebra is obtained from the Poincare algebra by taking the speed of light to zero, and the conformal version similarly follows. In the first half of the talk, we construct explicit examples of Conformal Carrollian field theories (CCFTs) as limits of relativistic conformal theories where even in dimensions d = 4, there is an infinite enhancement of the underlying symmetry structure. Due to the isomorphism with BMS symmetries, these field theories form prototypical examples of holographic duals to gravitational theories in asymptotically flat spacetimes. Then we discuss the intrinsic approach where we propose an action for the Carrollian scalar electrodynamics. The action formalism neither relies on the limiting approach nor its parent relativistic theory. The action seems to be the first example of any interacting CCFT and it respects the finite and infinite conformal Carrollian symmetries in d = 4. We will see that the infinite Carrollian conformal algebra is satisfied at the level of charges corresponding to the Carrollian symmetries. Our analysis is general enough to suggest that this infinite enhancement is a generic feature of the ultra-relativistic limit that we consider.