Gravitational Self-Force and Scattering Amplitudes Workshop

4305 (Higgs Centre Seminar Room)


Higgs Centre Seminar Room

James Clerk Maxwell Building Edinburgh EH9 3FD
Riccardo Gonzo (University of Edinburgh), Chris Kavanagh (University College Dublin), Adam Pound (University of Southampton), Mao Zeng (The University of Edinburgh)

Recent developments in scattering amplitudes have given new insights into the classical two-body dynamics in the post-Minkowskian expansion (i.e., expansion in Newton's constant), leveraging extremely efficient computational techniques traditionally used for collider physics. At the same time, the gravitational self-force expansion has allowed the gravitational-wave community to develop a description of the two-body dynamics which is fully non-perturbative in the coupling, while being accurate only in the limit of small mass ratios.

There are exciting prospects in uniting these two complementary approaches, possibly yielding powerful new modeling methods for gravitational-wave astronomy and new insights into the connections between gravity and amplitudes. In the past year there have been notable steps toward this goal, but much more remains to be done to fully benefit from synergies between the two methods. This workshop will bring together experts from both communities to establish new collaborations, with the following topics to be discussed:

  • recovering self-force through resummation of PM results;
  • comparison between self-force and analytical post-Newtonian/post-Minkowskian results;
  • Kerr black holes from amplitudes and point particles;
  • double copy structures in classical gravity and black hole perturbation theory.

Confirmed speakers:

Clifford Cheung, Thibault Damour, Abraham Harte, Tanja Hinderer, Chris Kavanagh, Sonja Klisch, Dimitrios Kosmopoulos, Zhengwen Liu, Oliver Long, Gustav Mogull, Barry Wardell, Chris Whittall


Riccardo Gonzo, Chris Kavanagh, Adam Pound, Mao Zeng

All participants will be treated equally without regard to gender, sexual orientation, race, age, religion, disability, or any other circumstance. Participants from underrepresented and traditionally disadvantaged backgrounds are particularly encouraged to register.

Note: If you are interested in this workshop, we encourage you to register before February 20th 2024. Unfortunately our space is limited, so we will moderate the registration and cannot guarantee at this point to be able to offer to everyone the possibility to attend in person. Talks will be anyway recorded and posted here, so they will be available to everyone.

Workshop Registration
  • Abraham Harte
  • Adam Pound
  • Alan Müller
  • Andres Luna
  • Anton Ilderton
  • Asaad Elkhidir
  • Barry Wardell
  • Bin Zhu
  • Brad Cownden
  • Canxin Shi
  • Chris Kavanagh
  • Christopher Whittall
  • Clifford Cheung
  • David Kosower
  • Davide Usseglio
  • Dimitrios Kosmopoulos
  • Dogan Akpinar
  • Dominik Rist
  • Francesco Alessio
  • Giuseppe De Laurentis
  • Gustav Jakobsen
  • Gustav Mogull
  • Iustin Surubaru
  • Jack Lewis
  • Jakob Neef
  • Jitze Hoogeveen
  • Justin Vines
  • Jørgen Musaeus
  • Karthik Rajeev
  • Mao Zeng
  • Misbah Shahzadi
  • Mohammed Aasir Afzal Khan
  • Nathan Moynihan
  • Ofri Telem
  • Oliver Long
  • Paul Ramond
  • Rafael Porto
  • Riccardo Gonzo
  • Sam Dolan
  • Samuel Upton
  • Saptaswa Ghosh
  • Sonja Klisch
  • Sri Aravind Jaganathan
  • Surajit Ghosh
  • Tanja Hinderer
  • Thibault DAMOUR
  • Tim Adamo
  • Vittorio Del Duca
  • Wei Bu
  • Zhengwen Liu
    • 08:45 09:15
    • 09:15 09:30
      Welcome session
    • 09:30 10:30
      ACV, BCJ, EFT, EOB, MPM, PM, PN, QFT, SF, WQFT and All That (Thibault Damour) 1h

      A personal perspective on the recently explored synergies between various
      approaches to the general relativistic two-body problem will be presented.

      Speaker: Thibault Damour (IHES)
    • 10:30 11:00
      Coffee break 30m
    • 11:00 12:00
      Analytic self-force: Bound and Unbound -PN, PM, SF and just that (Chris Kavanagh) 1h
      Speaker: Chris Kavanagh
    • 12:00 12:10
      Group picture
    • 12:10 13:30
      Lunch 1h 20m
    • 13:30 14:30
      State of the art in gravitational self-force (Barry Wardell) 1h
      Speaker: Barry Wardell
    • 14:30 15:00
      Coffee break 30m
    • 15:00 16:00
      Discussion session: Waveforms, spin and amplitudes (Radu Roiban)
    • 17:00 18:30
      Welcome reception
    • 09:30 10:30
      Self-force in black hole scattering: a scalar-field toy model (Chris Whittall) 1h

      Calculations of the scattering angle in hyperbolic black hole encounters have been of recent cross-disciplinary interest, driven by its potential to advance post-Minkowskian theory and the effective-one-body model of binary dynamics. In this talk I will consider the self-force approach to modelling black hole scattering, starting with a general introduction to self-force theory and the motivation for self-force scattering. I will then introduce the scalar-field toy model that has been widely used in recent self-force scattering research, and describe our efforts to develop a frequency-domain numerical method to calculate the scalar-field self-force during hyperbolic encounters. I will end the talk by discussing some ongoing areas of work in self-force scattering, in particular the use of self-force results to resum analytical post-Minkowskian series, and work to obtain analytical results for the self-force at early and late times along scattering orbits.

      Speaker: Chris Whittall
    • 10:30 11:00
      Coffee break 30m
    • 11:00 12:00
      Comparing numeric and analytic methods for black hole scattering in unequal mass systems (Oliver Long) 1h

      In this talk, we address the significance of studying hyperbolic orbits in gravitational physics by comparing different methods of calculating scattering observables. We begin by detailing a numerical calculation method for the scalar self-force correction to the scattering angle and juxtapose these results with analytical expressions derived from scattering-amplitude methods, up to fourth post-Minkowskian order. We then provide an overview of the current state of modelling scattering orbits within Numerical Relativity. Specifically, we compare preliminary results of unequal mass hyperbolic binary black hole encounters obtained through Numerical Relativity simulations with predictions from post-Minkowskian and Effective One Body methods. Our findings shed light on the strengths and limitations of each method and pave the way for further advancements in understanding hyperbolic encounters in gravitational systems.

      Speaker: Oliver Long (AEI)
    • 12:00 13:30
      Lunch 1h 30m
    • 13:30 14:30
      Wonders of Kerr-Schild geometry (Abraham Harte) 1h

      Kerr-Schild geometry has recently seen a surge of interest, appearing in double-copy constructions, in the highly-regular gauge used in the second-order self-force, and elsewhere. This talk explores some of the remarkable properties of Kerr-Schild geometry: It can be used to eliminate nonlinearities in Einstein's equation, can improve accuracy in perturbation theory, can be used to generate large classes of new solutions to Maxwell's equations, and also to generate new solutions for high-frequency gravitational (and other) waves. These results provide a wealth of new tools which have just begun to be explored.

      Speaker: Abraham Harte
    • 14:30 15:00
      Coffee break 30m
    • 15:00 16:00
      Discussion session: What can PM do for GSF? What can GSF do for PM? (Adam Pound)
    • 09:30 10:30
      Gravitational Self Force from Scattering Amplitudes in Curved Space (Dimitrios Kosmopoulos) 1h

      I will present a novel approach for calculating observables in the context of the binary inspiral problem which is designed to leverage the all-orders-in-G information carried by exact solutions of the Einstein equations. This framework computes scattering amplitudes in the curved-space setup where a light particle of mass m is treated as a probe in the geometry sourced by a heavy particle of mass M. Observables are organized in the gravitational self-force expansion, i.e. as an expansion in m/M. Backreaction of the background is captured via Goldstone bosons associated with the spontaneous breaking of spacetime symmetries. I will discuss advantages introduced by this formalism and cross checks against the literature.

      Speaker: Dimitrios Kosmopoulos
    • 10:30 11:00
      Coffee break 30m
    • 11:00 12:00
      On-shell approaches to self-force using amplitudes on backgrounds (Sonja Klisch) 1h

      At leading order, the self-force expansion describes the geodesic motion of a massive point particle on a non-trivial background. Consequently, if we seek to calculate classical observables in this expansion using scattering amplitudes, a natural starting point is from a QFT on this non-trivial background. Amplitudes here capture the full non-linearities of the theory, including effects such as memory and gravitational tails. In this talk I will present some recent and upcoming work using this approach, including the calculation of the waveform from massive scattering on a gravitational plane wave, scattering amplitudes on Schwarzschild, and amplitudes in Einstein-Maxwell on strong backgrounds.

      Speaker: Sonja Klisch
    • 12:00 13:30
      Lunch 1h 30m
    • 13:30 14:30
      An Effective Field Theory for Extreme Mass Ratios (Clifford Cheung) 1h
      Speaker: Clifford Cheung
    • 14:30 15:00
      Coffee break 30m
    • 15:00 16:00
      Discussion session: Analytical insights to GSF from particle physics (Riccardo Gonzo, Ofri Telem)
    • 19:30 22:30
      Dinner: Amber restaurant, 354 Castlehill, Edinburgh EH1 2NE
    • 09:30 10:30
      Gravitational two-body dynamics at NNNLO in post-Minkowskian approximation (Zhengwen Liu) 1h

      High-accuracy theoretical predictions for the motion of compact binary systems are crucial for maximizing the discovery potential of current and future gravitational-wave observations, such as LIGO-Virgo-Kagra and LISA. The Effective Field Theory methodology, combined with modern multi-loop techniques, has proven to be exceptionally powerful for analytically solving the gravitational two-body inspiralling problem in post-Minkowskian approximation. This talk explore recent advancements in the worldline EFT and its application in computing two-body inspiralling dynamics, with a focus on the recently-obtained results at the fourth PM order (NNNLO).

      Speaker: Zhengwen Liu
    • 10:30 11:00
      Coffee break 30m
    • 11:00 12:00
      Conservative Black Hole Scattering at 5PM-1SF Order (Gustav Mogull) 1h

      In this talk I will discuss our recent calculation of the conservative fifth post-Minkowskian (5PM) scattering angle, at first order in self-force, using the Worldline Quantum Field Theory (WQFT) formalism. This challenging calculation involved performing four-loop Feynman integrals, and surprisingly resulted in a total absence of the elliptic functions present at 4PM order — the entire result is expressed on a basis of weight-3 multiple polylogarithms (MPLs).

      Speaker: Gustav Mogull
    • 12:00 13:00
      Lunch 1h
    • 13:00 14:10
      Colloquium: Probing subatomic physics with gravitational waves from neutron star binary inspirals(Tanja Hinderer)
    • 14:10 14:30
      Closing remarks
    • 14:30 15:00
      Pre-departure Coffee and Tea 30m
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