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DTSTART;TZID=America/New_York:20220621T090000
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SUMMARY:Joint BHI/CMSA Conference on Flat Holography
DESCRIPTION: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). \nThe 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. \nThe conference was held in room G10 of the CMSA\, 20 Garden Street\, Cambridge\, MA. \nOrganizers: \n\nDaniel Kapec\, CMSA\nAndrew Strominger\, BHI\nShing-Tung Yau\, Harvard & Tsinghua\n\nConfirmed Speakers: \n\nNima Arkani-Hamed\, IAS\nShamik Banerjee\, Bhubaneswar\, Inst. Phys.\nMiguel Campiglia\, Republica U.\, Montevido\nGeoffrey Compere\, Brussels\nLaura Donnay\, Vienna\nNetta Engelhardt\, MIT\nLaurent Freidel\, Perimeter\nAlex Lupsasca\, Princeton\nJuan Maldacena\, IAS\nLionel Mason\, Oxford\nNatalie Paquette\, U. Washington\nSabrina Pasterski\, Princeton/Perimeter\nAndrea Puhm\, Ecole Polytechnique\nAna-Maria Raclariu\, Perimeter\nMarcus Spradlin\, Brown\nTomasz Taylor\, Northeastern\nHerman Verlinde\, Princeton\nAnastasia Volovich\, Brown\nBin Zhu\, Northeastern\n\nShort 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) \n\n\nSchedule\nMonday\, June 20\, 2022 \n\n\n\n\n\nArrival\n\n\n7:00–9:00 pm\nWelcome Reception at Andy’s residence\n\n\n\n\n  \nTuesday\, June 21\, 2022 \n\n\n\n\n9:00–9:30 am\nBreakfast\nlight breakfast provided\n\n\n\nMorning Session\nChair: Dan Kapec\n\n\n9:30–10:00 am\nHerman Verlinde\nTitle: Comments on Celestial Dynamics\n\n\n10:00–10:30 am\nJuan Maldacena\nTitle: What happens when you spend too much time looking at supersymmetric\nblack holes?\n\n\n10:30–11:00\nCoffee break\n\n\n\n11:00–11:30 am\nMiguel Campiglia\nTitle: Asymptotic symmetries and loop corrections to soft theorems\n\n\n11:30–12:00 pm\nGeoffrey Compere\nTitle: Metric reconstruction from $Lw_{1+\infty}$ multipoles \nAbstract: 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.\n\n\n12:00–2:00 pm\nLunch break\n\n\n\n\nAfternoon Session\nChair: Eduardo Casali\n\n\n2:00–2:30 pm\nNatalie Paquette\nTitle: New thoughts on old gauge amplitudes\n\n\n2:30–3:00 pm\nLionel Mason\nTitle: An open sigma model for celestial gravity \nAbstract: 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.\n\n\n3:00–3:30 pm\nCoffee break\n\n\n\n3:30–4:30 pm\nShort Talks\nDaniel Kapec: Soft Scalars and the Geometry of the Space of Celestial CFTs \nAlbert Law: Soft Scalars and the Geometry of the Space of Celestial CFTs \nSruthi Narayanan: Soft Scalars and the Geometry of the Space of Celestial CFTs \nStéphane Detournay: Non-conformal symmetries and near-extremal black holes \nFrancisco Rojas: Celestial string amplitudes beyond tree level \nTemple He: An effective description of energy transport from holography\n\n\n4:30–5:00 pm\nNima Arkani-Hamed\n(Dual) surfacehedra and flow particles know about strings\n\n\n\n\n  \nWednesday\, June 22\, 2022 \n\n\n\n\n9:00–9:30 am\nBreakfast\nlight breakfast provided\n\n\n\nMorning Session\nChair: Alfredo Guevara\n\n\n9:30–10:00 am\nLaurent Freidel\nTitle: Higher spin symmetry in gravity \nAbstract: In this talk\, I will review how the gravitational conservation laws at infinity reveal a tower of symmetry charges in an asymptotically flat spacetime.\nI will show how the conservation laws\, at spacelike infinity\, give a tower of soft theorems that connect to the ones revealed by celestial holography.\nI’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:\nsuch 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.\n\n\n10:00–10:30 am\nAna-Maria Raclariu\nTitle: Eikonal approximation in celestial CFT\n\n\n10:30–11:00 am\nCoffee break\n\n\n\n11:00–11:30 am\nAnastasia Volovich\nTitle: Effective Field Theories with Celestial Duals\n\n\n11:30–12:00 pm\nMarcus Spradlin\nTitle: Loop level gluon OPE’s in celestial holography\n\n\n12:00–2:00 pm\nLunch break\n\n\n\n\nAfternoon Session\nChair: Chiara Toldo\n\n\n2:00–2:30 pm\nNetta Engelhardt\nTitle: Wormholes from entanglement: true or false?\n\n\n2:30–3:00 pm\nShort Talks\nLuke Lippstreu: Loop corrections to the OPE of celestial gluons \nYangrui Hu: Light transforms of celestial amplitudes \nLecheng Ren: All-order OPE expansion of celestial gluon and graviton primaries from MHV amplitudes\n\n\n3:00–3:30 pm\nCoffee break\n\n\n\n3:30–4:30 pm\nShort Talks\nNoah Miller: C Metric Thermodynamics \nErin Crawley: Kleinian black holes \nRifath Khan: Cauchy Slice Holography: A New AdS/CFT Dictionary \nGonçalo Araujo-Regado: Cauchy Slice Holography: A New AdS/CFT Dictionary \nTianli Wang: Soft Theorem in the BFSS Matrix Model \nAdam Tropper: Soft Theorem in the BFSS Matrix Model\n\n\n7:00–9:00 pm\nBanquet\nMaharaja Restaurant\, 57 JFK Street\, Cambridge\, MA\n\n\n\n\n  \nThursday\, June 23\, 2022 \n\n\n\n\n9:00–9:30 am\nBreakfast\nlight breakfast provided\n\n\n\nMorning Session\nChair: Jordan Cotler\n\n\n9:30–10:00 am\nLaura Donnay\nTitle: A Carrollian road to flat space holography\n\n\n10:00–10:30 am\nAndrea Puhm\nTitle: Celestial wave scattering on Kerr-Schild backgrounds\n\n\n10:30–11:00 am\nCoffee break\n\n\n\n11:00–11:30 am\nSabrina Pasterski\nTitle: Mining Celestial Symmetries \nAbstract: 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. \nCome prepared to debate the central charge\, loop corrections\, contour prescriptions\, and orders of limits!\n\n\n11:30–12:00 pm\nShamik Banerjee\nTitle: Virasoro and other symmetries in CCFT \nAbstract:  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.\n\n\n12:00–2:00 pm\nLunch break\n\n\n\n\nAfternoon Session\nChair: Albert Law\n\n\n2:00–2:30 pm\nTomasz Taylor\nTitle: Celestial Yang-Mills amplitudes and D=4 conformal blocks\n\n\n2:30–3:00 pm\nBin Zhu\nTitle:  Single-valued correlators and Banerjee-Ghosh equations \nAbstract:  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.\n\n\n3:00–3:30 pm\nCoffee break\n\n\n\n3:30–4:00 pm\nAlex Lupsasca\nTitle: Holography of the Photon Ring\n\n\n4:00–5:30 pm\nShort Talks\nElizabeth Himwich: Celestial OPEs and w(1+infinity) symmetry of massless and massive amplitudes \nAdam Ball: Perturbatively exact $w_{1+\infty}$ asymptotic symmetry of quantum self-dual gravity \nRomain Ruzziconi: A Carrollian Perspective on Celestial Holography \nJordan Cotler: Soft Gravitons in 3D \nAlfredo Guevara: Comments on w_1+\inf \nAndrew Strominger: Top-down celestial holograms \nEduardo Casali: Celestial amplitudes as AdS-Witten diagrams \nWalker Melton: Top-down celestial holograms\n\n\n\n\n  \nFriday\, June 24\, 2022 \n\n\n\n\n9:00–9:30 am\nBreakfast\n\n\n9:30–12:30 pm\nOpen Discussion\n\n\n12:30–2:30 pm\nLunch provided at the BHI\n\n\n\nDeparture\n\n\n\n\n 
URL:https://cmsa.fas.harvard.edu/event/joint-bhi-cmsa-conference-on-flat-holography/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Conference,Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Flat-Holography_2022_small.png
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