#### Hall 123

#### Towards flat space holography

#### Aneesh P B

##### IMSc

*I will review the story of asymptotic symmetries of asymptotically flat spacetimes in 4 dimensions. The progress in this direction seems to suggest a putative holographic theory (a celestial CFT) that lives on a 2-d sphere called the celestial sphere. The correlators that one computes in this theory are related to the Mellin transform of the S-matrix for massless particles. In particular this suggests a codimension-2 type holography.*

Independently, if one parallels the AdS/CFT story where we have a codimension-1 holographic theory, one is led to suspect that a putative holographic theory should live at scri. Given the null nature of scri, this suggests that the putative holographic theory should be a conformal Carrollian field theory.

One is naturally led to the question if these two approaches are equivalent/related. I will motivate a possible way to relate the two via a modified Mellin transform.

Done