2025 Simons Collaboration on Celestial Holography Annual Meeting

Kevin Costello
Perimeter Institute

Non-Perturbative Aspects of Self-Dual Gauge Theory

Self-dual gauge theory is conformal in perturbation theory but has a non-trivial beta-function when instanton effects are included. Kevin Costello will give two computations of this beta-function, one based on the Grothendieck-Riemann-Roch formula and one using holography in the topological string. This leads to two new ways to compute the standard QCD beta-function at one loop, without using Feynman diagrams. If time permits, Costello will also discuss how instantons effect scattering amplitudes.
 

Wei Song
Tsinghua University

The TsT/TTbar Correspondence: A Top-Down Approach of Non-AdS Holography

The TsT/TTbar correspondence is an example of non-AdS holography constructed from string theory. Beginning with Type IIB string theory on AdS₃ × N with NS-NS three-form flux, and applying TsT transformations (comprising T-duality, a shift, and another T-duality), one can obtain an asymptotically flat spacetime featuring a linear dilaton in the string frame. The holographic dual of this configuration is closely connected to a single-trace version of the TTbar-deformed conformal field theory (CFT) in two dimensions. Wei Song will discuss various aspects of this model, such as the spectrum, black holes, symmetries, and correlation functions.
 

Raphael Bousso
University of California, Berkeley

Holograms in Asymptotically Flat Space

[Based on joint works with Geoff Penington and with Sami Kaya.] Raphael Bousso will review and refine the construction of generalized entanglement wedges. Bousso will then specialize to the case of asymptotically flat spacetimes and classify the asymptotic boundaries of wedges and entanglement wedges. Raphael will recover the notion of entanglement wedge complementarity, which are richer and more subtle than in AdS.
 

David Skinner
University of Cambridge

Celestial Holography and Self-Dual Einstein Gravity

To date, top-down constructions of celestial holography involve a combination of twisted holography and twistor theory. In the original (Burns) model of Costello-Paquette-Sharma, the gravitational theory is the B model living in a suitable twistor space, and corresponds to a theory of self-dual conformal gravity in four dimensions. David Skinner will discuss a variant of this model coming from a CY 5-fold that admits a K3 fibration over twistor space and yields a theory of self-dual Einstein gravity in four dimensions. This is based on work in progress with Roland Bittleston, Kevin Costello, and Atul Sharma.
 

Nima Arkani-Hamed
Institute for Advanced Study

1/n

TBA
 

Edward Witten
Institute for Advanced Study

A Background Independent Algebra in Quantum Gravity

Edward Witten will consider the algebra of observables along the worldline of an observer as a background independent algebra in quantum gravity.
 

Sabrina Pasterski
Perimeter Institute

Lifting Swing Surfaces to AdS

The entanglement entropy for regions in a BMS field theory living at null infinity has been proposed to be holographically dual to certain ‘swing surfaces’ in flat space. Sabrina Pasterski will lift this construction to AdS/CFT and revisit both bulk and boundary aspects of this proposal.
 

Ashoke Sen
International Center for Theoretical Sciences

Classical Gravitational Wave Tails from Soft Theorem

If a set of massive objects collide in space, and the fragments disperse, possibly forming black holes, then this process will emit gravitational waves. Computing the detailed gravitational wave-form associated with this process is a complicated problem, not only due to the non-linearity of gravity but also due to the fact that during the collision and subsequent fragmentation the objects could undergo complicated non-gravitational interactions. Nevertheless, the classical soft graviton theorem determines the power law fall-off of the wave-form at late and early times, including logarithmic corrections, in terms of only the momenta of the incoming and outgoing objects without any reference to what transpired during the collision. Ashoke will explain the results, briefly outline the derivation of these results and discuss possible generalizations and applications.

Participation in the meeting falls into the following four categories. An individual’s participation category is communicated via their letter of invitation.

The Simons Foundation will never ask for credit card information or require payment for registration to our events.

Group A – PIs and Speakers

Economy Class: For flights that are three hours or less to your destination, the maximum allowable class of service is Economy class.
Premium Economy Class: For flights where the total air travel time (excluding connection time) is more than three hours and less than seven hours per segment to your destination, the maximum allowable class of service is premium economy.
Business Class: When traveling internationally (or to Hawaii/Alaska) travelers are permitted to travel in Business Class on those segments that are seven hours or more. If the routing is over budget, a premium economy or mixed-class ticket will be booked.

Group B – Funded Participants

The foundation will arrange and pay for round-trip air or train travel to the conference as well as hotel accommodations and reimbursement of local expenses. Economy-class airfare will be booked for all flights.

Group C – Unfunded Participants

Individuals in Group C will not receive financial support, but are encouraged to enjoy all conference-hosted meals.

Group D – Remote Participants

Individuals in Group D will participate in the meeting remotely.

Air and Rail

For funded individuals, the foundation will arrange and pay for round-trip travel from their home city to the conference.

All travel and hotel arrangements must be booked through the Simons Foundation’s preferred travel agency.

Travel Deviations

The following travel specifications are considered deviations and will only be accommodated if the cost is less than or equal to the amount the Simons Foundation would pay for a standard round-trip ticket from your home city to the conference city:

• Preferred airline
• Preferred travel class
• Specific flights/flight times
• Travel dates outside those associated with the conference
• Arriving or departing from an airport other than your home city or conference city airports, i.e. multi-segment or triangle trips.

All deviations must be reviewed and approved by the Simons Foundation and, if the cost is in excess of what would normally be paid, a reimbursement quote must be obtained through the foundation’s travel agency before proceeding to booking and paying for travel out of pocket. All reimbursements for travel booked directly will be paid after the conclusion of the meeting.

Changes After Ticketing

All costs related to changes made to ticketed travel are to be paid for by the participant and are not reimbursable. Please contact the foundation’s travel agency for further assistance.

Personal & Rental Cars

Personal car and rental trips over 250 miles each way require prior approval from the Simons Foundation via email.

Rental cars must be pre-approved by the Simons Foundation.

The James NoMad Hotel offers valet parking. Please note there are no in-and-out privileges when using the hotel’s garage, therefore it is encouraged that participants walk or take public transportation to the Simons Foundation.

Hotel

Funded individuals who require hotel accommodations are hosted by the foundation for a maximum of three nights at The James NoMad Hotel, arriving one day before the meeting and departing one day after the meeting.

Any additional nights are at the attendee’s own expense. To arrange accommodations, please register at the link included in your invitation.

The James NoMad Hotel
22 E 29th St
New York, NY 10016
(between 28th and 29th Streets)
https://www.jameshotels.com/new-york-nomad/

For driving directions to The James NoMad, please click here.

Overview

In-person participants will be reimbursed for meals and local expenses including ground transportation. Expenses should be submitted through the foundation’s online expense reimbursement platform after the meeting’s conclusion.

Expenses accrued as a result of meetings not directly related to the Simons Foundation-hosted meeting (a meeting held at another institution, for example) will not be reimbursed by the Simons Foundation and should be paid by other sources.

Below are key reimbursement takeaways; a full policy will be provided with the final logistics email circulated approximately 2 weeks prior to the meeting’s start.

Meals

The daily meal limit is $125; itemized receipts are required for expenses over $24 USD. The foundation DOES NOT provide a meal per diem and only reimburses actual meal expenses up the following amounts.

• Breakfast $20
• Lunch $30
• Dinner $75

Allowable Meal Expenses

• Meals taken on travel days (when you traveled by air or train).
• Meals not provided on a meeting day, dinner on Friday for example.
• Group dinners consisting of fellow meeting participants paid by a single person will be reimbursed up to $75 per person and the amount will count towards each individual’s $125 daily meal limit.

Unallowable Meal Expenses

• Meals taken outside those provided by the foundation (breakfast, lunch, breaks and/or dinner).
• Meals taken on days not associated with Simons Foundation-coordinated events.
• Minibar expenses.
• Meal expenses for a non-foundation guest.

• Ubers, Lyfts, taxis, etc., taken to and from restaurants in Manhattan.

  • Accommodations will be made for those with mobility restrictions.

Ground Transportation

Expenses for ground transportation will be reimbursed for travel days (i.e. traveling to/from the airport or train station) as well as subway and bus fares while in Manhattan are reimbursable.

Transportation to/from satellite meetings are not reimbursable.

Attendance

In-person participants and speakers are expected to attend all meeting days. Participants receiving hotel and travel support wishing to arrive on meeting days which conclude at 2:00 PM will be asked to attend remotely.

Entry & Building Access

Upon arrival, guests will be required to show their photo ID to enter the Simons Foundation and Flatiron Institute buildings. After checking-in at the meeting reception desk, guests will be able to show their meeting name badge to re-enter the building. If you forget your name badge, you will need to provide your photo ID.

The Simons Foundation and Flatiron Institute buildings are not considered “open campuses” and meeting participants will only have access to the spaces in which the meeting will take place. All other areas are off limits without prior approval.

If you require a private space to conduct a phone call or remote meeting, please contact your meeting manager at least 48-hours ahead of time so that they may book a space for you within the foundation’s room reservation system.

Guests & Children

Meeting participants are required to give 24 hour advance notice of any guests meeting them at the Simons Foundation either before or after the meeting. Outside guests are discouraged from joining meeting activities, including meals.

With the exception of Simons Foundation and Flatiron Institute staff, ad hoc meeting participants who did not receive a meeting invitation directly from the Simons Foundation are not permitted.

Children under the age of 18 are not permitted to attend meetings at the Simons Foundation. Furthermore, the Simons Foundation does not provide childcare facilities or support of any kind. Special accommodations will be made for nursing parents.

Meeting & Policy Questions

Meghan Fazzi
Senior Manager, Events & Administration, MPS
mfazzi@simonsfoundation.org

Travel & Hotel Support

FCM Travel Meetings & Events
SimonsFoundationEventTravel@us.fcm.travel
Hours: M-F, 8:30 AM-5:00 PM ET
+1-877-300-7108