The holographic principle provides a primary route toward the theory of quantum gravity. According to this principle, quantum theories of gravity are holographic in nature and hence can be equivalently described by a dual quantum field theory that lives on its boundary. Although this principle is very well established for asymptotically AdS spacetimes, the similar picture for asymptotically flat spacetimes is still far from complete. The approach towards building a dual theory of flat spacetimes has taken two routes, Celestial and Carrollian. Celestial holography emerged from a crucial discovery of the infrared triangle that connects soft theorems, memory effect and asymptotic symmetries. This proposal captures the bulk scattering amplitudes by correlation functions of a 2d CFT that lives on the celestial sphere. Soft theorems are then realised as ward identity of 2d celestial CFT.
However, there is a parallel approach where the dual theory is spanned over the null boundary instead of the celestial sphere, hence Carrollian in nature. This perspective has been very successful for lower-dimensional cases but remains much less investigated in higher-dimensional contexts. During my stay at the ESI, I shall study various aspects of Carrollian CFTs on higher dimensions and link up with bulk scattering amplitudes. I shall compute the ward identities of these theories and see the role of these identities at the level of scattering amplitudes, aiming to derive soft theorems in this framework. I also intend to investigate these theories' vacuum structures and possible vacuum transitions, which might lead to the memory effect. Understanding scattering amplitudes and their infrared properties in this framework would provide necessary insights to bridge the gap between these two approaches of flat space holography.
Duration of stay: 1st September 2022 - 31st December 2022
|Sudipta Dutta||Indian Institute of Technology Kanpur|