Abstract: The most general vacuum solution to Einstein’s field equations with no incoming radiation can be constructed perturbatively from two infinite sets of canonical multipole moments, which are found to be exchanged under gravitational electric-magnetic duality at the non-linear level. We demonstrate that in non-radiative regions such spacetimes are completely determined by a set of conserved celestial charges, which uniquely label transitions among non-radiative regions caused by radiative processes. The algebra of the conserved celestial charges is derived from the real $Lw_{1+\infty}$ algebra. The celestial charges are expressed in terms of multipole moments, which allows to holographically reconstruct the metric in de Donder, Newman-Unti or Bondi gauge outside of sources.

Abstract: A global twistor construction for conformally self-dual split signature metrics on $S²\times S²$  was developed 15 years ago by Claude LeBrun and the speaker.  This encodes the conformal metric into the location of a finite deformation of the real twistor space inside the flat complex twistor space, $\mathbb{CP}³$. This talk adapts the construction to construct global SD Einstein metrics from conformal boundary data and perturbations around the self-dual sector.  The construction entails determining a family of holomorphic discs in $\mathbb{CP}³$ whose boundaries lie on the deformed real slice and the (chiral) sigma model controls these discs in the Einstein case and provides amplitude formulae.

Albert Law: Soft Scalars and the Geometry of the Space of Celestial CFTs

Sruthi Narayanan: Soft Scalars and the Geometry of the Space of Celestial CFTs

Stéphane Detournay: Non-conformal symmetries and near-extremal black holes

Francisco Rojas: Celestial string amplitudes beyond tree level

Temple He: An effective description of energy transport from holography

Abstract: In this talk, I will review how the gravitational conservation laws at infinity reveal a tower of symmetry charges in an asymptotically flat spacetime.
I will show how the conservation laws, at spacelike infinity, give a tower of soft theorems that connect to the ones revealed by celestial holography.
I’ll present the expression for the symmetry charges in the radiative phase space, which opens the way to reveal the structure of the algebra beyond the positive helicity sector. Then, if time permits I’ll browse through many questions that these results raise:
such as the nature of the spacetime symmetry these charges represent, the nature of the relationship with multipole moments, and the insights their presence provides for quantum gravity.

Yangrui Hu: Light transforms of celestial amplitudes

Lecheng Ren: All-order OPE expansion of celestial gluon and graviton primaries from MHV amplitudes

Erin Crawley: Kleinian black holes

Rifath Khan: Cauchy Slice Holography: A New AdS/CFT Dictionary

Gonçalo Araujo-Regado: Cauchy Slice Holography: A New AdS/CFT Dictionary

Tianli Wang: Soft Theorem in the BFSS Matrix Model

Adam Tropper: Soft Theorem in the BFSS Matrix Model

Abstract: The aim of this talk is to delve into the common thread that ties together recent work with H. Verlinde, L. Donnay, A. Puhm, and S. Banerjee exploring, explaining, and exploiting the symmetries encoded in the conformally soft sector.

Come prepared to debate the central charge, loop corrections, contour prescriptions, and orders of limits!

Abstract:  In this talk I will briefly describe my ongoing work with Sabrina Pasterski. In this work we revisit the standard construction of the celestial stress tensor as a shadow of the subleading conformally soft graviton.  In its original formulation, we find that there is an obstruction to reproducing the expected $TT$ OPE in the double soft limit. This obstruction is related to the existence of the $SL_2$ current algebra symmetry of the CCFT. We propose a modification to the definition of the stress tensor which circumvents this obstruction and also discuss its implications for the existence of other current algebra (w_{1+\infty}) symmetries in CCFT.

Abstract:  Low-point celestial amplitudes are plagued with singularities resulting from spacetime translation. We consider a marginal deformation of the celestial CFT which is realized by coupling Yang-Mills theory to a background dilaton field, with the (complex) dilaton source localized on the celestial sphere. This picture emerges from the physical interpretation of the solutions of the system of differential equations discovered by Banerjee and Ghosh. We show that the solutions can be written as Mellin transforms of the amplitudes evaluated in such a dilaton background. The resultant three-gluon and four-gluon amplitudes are single-valued functions of celestial coordinates enjoying crossing symmetry and all other properties expected from standard CFT correlators.

Adam Ball: Perturbatively exact $w_{1+\infty}$ asymptotic symmetry of quantum self-dual gravity

Romain Ruzziconi: A Carrollian Perspective on Celestial Holography

Jordan Cotler: Soft Gravitons in 3D

Alfredo Guevara: Comments on w_1+\inf

Andrew Strominger: Top-down celestial holograms

Eduardo Casali: Celestial amplitudes as AdS-Witten diagrams

Walker Melton: Top-down celestial holograms