ITMP Seminar "Celestial CFT Correlators and Conformal Block Decomposition"

Dear Colleagues,

We are pleased to announce that the next ITMP seminar will be held on Wednesday, June 2, at 19:30 (Moscow time). The seminar will be arranged via Zoom. 

Speaker: Dr. Angelos Fotopoulos, Northeastern University, Boston

Title: Celestial CFT Correlators and Conformal Block Decomposition

Abstract: I will shortly review the connection of the Bondi-van der Burg-Metzner-Sachs (BMS) symmetry group of asymptotically flat four-dimensional spacetimes at null infinity to the S-matrix of elementary particles and gravitons. 

Applying Mellin transformations to traditional, momentum space amplitudes we can compute celestial amplitudes. These are conjectured to correspond to correlators of conformal primary fields on a putative two-dimensional celestial sphere. I will elaborate on the proposal of flat holography in which four-dimensional physics is encoded in two-dimensional celestial conformal field theory (CCFT). The symmetry underlying CCFT is the extended BMS symmetry of (asymptotically) flat spacetime. I will show how to use soft and collinear theorems of Einstein-Yang-Mills theory to derive the OPEs of BMS field operators generating the symmetries of the BMS group, superrotations and supertranslations. 

In the second part of my talk, time permitted, I will discuss a proposal for radial quantization of the CCFT and I will present an attempt to decompose gluon celestial amplitudes in conformal blocks. This will reveal some very interesting aspects of the Celestial CFT: the emergence of new operators in the theory and space-time scattering channels which lead to continuous complex spin primary fields. The space-time interpretation of these operators is still unclear. Moreover, CFT crossing symmetry and its relation to four-dimensional spacetime crossing symmetry of the S-matrix are some interesting open problems. 

If you want to join the seminar please register here before 14:00, June 2.

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