ACV, BCJ, EFT, EOB, MPM, PM, PN, QFT, SF, WQFT and All That (Thibault Damour)

• Thibault Damour (IHES)

Room: 4305 A personal perspective on the recently explored synergies between various approaches to the general relativistic two-body problem will be presented.

Analytic self-force: Bound and Unbound -PN, PM, SF and just that (Chris Kavanagh)

• Chris Kavanagh

Room: 4305

State of the art in gravitational self-force (Barry Wardell)

• Barry Wardell

Room: 4305

Self-force in black hole scattering: a scalar-field toy model (Chris Whittall)

• Chris Whittall

Room: 4305 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.

Comparing numeric and analytic methods for black hole scattering in unequal mass systems (Oliver Long)

• Oliver Long (AEI)

Room: 4305 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.

Wonders of Kerr-Schild geometry (Abraham Harte)

• Abraham Harte

Room: 4305 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.

Gravitational Self Force from Scattering Amplitudes in Curved Space (Dimitrios Kosmopoulos)

• Dimitrios Kosmopoulos

Room: 4305 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.

On-shell approaches to self-force using amplitudes on backgrounds (Sonja Klisch)

• Sonja Klisch

Room: 4305 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.

An Effective Field Theory for Extreme Mass Ratios (Clifford Cheung)

• Clifford Cheung

Room: 4305

Gravitational two-body dynamics at NNNLO in post-Minkowskian approximation (Zhengwen Liu)

• Zhengwen Liu

Room: 4305 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).

Conservative Black Hole Scattering at 5PM-1SF Order (Gustav Mogull)

• Gustav Mogull

Room: 4305 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).