On June 21–24, 2022, the Harvard Black Hole Initiative and the CMSA hosted the Joint BHI/CMSA Conference on Flat Holography (and related topics).
The recent discovery of infinitely-many soft symmetries for all quantum theories of gravity in asymptotically flat space has provided a promising starting point for a bottom-up construction of a holographic dual for the real world. Recent developments have brought together previously disparate studies of soft theorems, asymptotic symmetries, twistor theory, asymptotically flat black holes and their microscopic duals, self-dual gravity, and celestial scattering amplitudes, and link directly to AdS/CFT.
The conference was held in room G10 of the CMSA, 20 Garden Street, Cambridge, MA.
Organizers:
- Daniel Kapec, CMSA
- Andrew Strominger, BHI
- Shing-Tung Yau, Harvard & Tsinghua
Confirmed Speakers:
- Nima Arkani-Hamed, IAS
- Shamik Banerjee, Bhubaneswar, Inst. Phys.
- Miguel Campiglia, Republica U., Montevido
- Geoffrey Compere, Brussels
- Laura Donnay, Vienna
- Netta Engelhardt, MIT
- Laurent Freidel, Perimeter
- Alex Lupsasca, Princeton
- Juan Maldacena, IAS
- Lionel Mason, Oxford
- Natalie Paquette, U. Washington
- Sabrina Pasterski, Princeton/Perimeter
- Andrea Puhm, Ecole Polytechnique
- Ana-Maria Raclariu, Perimeter
- Marcus Spradlin, Brown
- Tomasz Taylor, Northeastern
- Herman Verlinde, Princeton
- Anastasia Volovich, Brown
- Bin Zhu, Northeastern
Short talks by: Gonçalo Araujo-Regado (Cambridge), Adam Ball (Harvard), Eduardo Casali (Harvard), Jordan Cotler (Harvard), Erin Crawley (Harvard), Stéphane Detournay (Brussels), Alfredo Guevara (Harvard), Temple He (UC Davis), Elizabeth Himwich (Harvard), Yangrui Hu (Brown), Daniel Kapec (Harvard), Rifath Khan (Cambridge), Albert Law (Harvard), Luke Lippstreu (Brown), Noah Miller (Harvard), Sruthi Narayanan (Harvard), Lecheng Ren (Brown), Francisco Rojas (UAI), Romain Ruzziconi (Vienna), Andrew Strominger (Harvard), Adam Tropper (Harvard), Tianli Wang (Harvard), Walker Melton (Harvard)
Schedule
Monday, June 20, 2022
Arrival | |
7:00–9:00 pm | Welcome Reception at Andy’s residence |
Tuesday, June 21, 2022
9:00–9:30 am | Breakfast | light breakfast provided |
Morning Session | Chair: Dan Kapec | |
9:30–10:00 am | Herman Verlinde | Title: Comments on Celestial Dynamics |
10:00–10:30 am | Juan Maldacena | Title: What happens when you spend too much time looking at supersymmetric black holes? |
10:30–11:00 | Coffee break | |
11:00–11:30 am | Miguel Campiglia | Title: Asymptotic symmetries and loop corrections to soft theorems |
11:30–12:00 pm | Geoffrey Compere | Title: Metric reconstruction from $Lw_{1+\infty}$ multipoles
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. |
12:00–2:00 pm | Lunch break | |
Afternoon Session | Chair: Eduardo Casali | |
2:00–2:30 pm | Natalie Paquette | Title: New thoughts on old gauge amplitudes |
2:30–3:00 pm | Lionel Mason | Title: An open sigma model for celestial gravity
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. |
3:00–3:30 pm | Coffee break | |
3:30–4:30 pm | Short Talks | Daniel Kapec: Soft Scalars and the Geometry of the Space of Celestial CFTs
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 |
4:30–5:00 pm | Nima Arkani-Hamed | (Dual) surfacehedra and flow particles know about strings |
Wednesday, June 22, 2022
9:00–9:30 am | Breakfast | light breakfast provided |
Morning Session | Chair: Alfredo Guevara | |
9:30–10:00 am | Laurent Freidel | Title: Higher spin symmetry in gravity
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. |
10:00–10:30 am | Ana-Maria Raclariu | Title: Eikonal approximation in celestial CFT |
10:30–11:00 am | Coffee break | |
11:00–11:30 am | Anastasia Volovich | Title: Effective Field Theories with Celestial Duals |
11:30–12:00 pm | Marcus Spradlin | Title: Loop level gluon OPE’s in celestial holography |
12:00–2:00 pm | Lunch break | |
Afternoon Session | Chair: Chiara Toldo | |
2:00–2:30 pm | Netta Engelhardt | Title: Wormholes from entanglement: true or false? |
2:30–3:00 pm | Short Talks | Luke Lippstreu: Loop corrections to the OPE of celestial gluons
Yangrui Hu: Light transforms of celestial amplitudes Lecheng Ren: All-order OPE expansion of celestial gluon and graviton primaries from MHV amplitudes |
3:00–3:30 pm | Coffee break | |
3:30–4:30 pm | Short Talks | Noah Miller: C Metric Thermodynamics
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 |
7:00–9:00 pm | Banquet | Maharaja Restaurant, 57 JFK Street, Cambridge, MA |
Thursday, June 23, 2022
9:00–9:30 am | Breakfast | light breakfast provided |
Morning Session | Chair: Jordan Cotler | |
9:30–10:00 am | Laura Donnay | Title: A Carrollian road to flat space holography |
10:00–10:30 am | Andrea Puhm | Title: Celestial wave scattering on Kerr-Schild backgrounds |
10:30–11:00 am | Coffee break | |
11:00–11:30 am | Sabrina Pasterski | Title: Mining Celestial Symmetries
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! |
11:30–12:00 pm | Shamik Banerjee | Title: Virasoro and other symmetries in CCFT
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. |
12:00–2:00 pm | Lunch break | |
Afternoon Session | Chair: Albert Law | |
2:00–2:30 pm | Tomasz Taylor | Title: Celestial Yang-Mills amplitudes and D=4 conformal blocks |
2:30–3:00 pm | Bin Zhu | Title: Single-valued correlators and Banerjee-Ghosh equations
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. |
3:00–3:30 pm | Coffee break | |
3:30–4:00 pm | Alex Lupsasca | Title: Holography of the Photon Ring |
4:00–5:30 pm | Short Talks | Elizabeth Himwich: Celestial OPEs and w(1+infinity) symmetry of massless and massive amplitudes
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 |
Friday, June 24, 2022
9:00–9:30 am | Breakfast |
9:30–12:30 pm | Open Discussion |
12:30–2:30 pm | Lunch provided at the BHI |
Departure |