SUSY in the Sky with Gravitons

Abstract

Picture yourself in the wave zone of a gravitational scattering event of two massive, spinning compact bodies (black holes, neutron stars or stars). We show that this system of genuine astrophysical interest enjoys a hidden N = 2 supersymmetry, at least to the order of spin-squared (quadrupole) interactions in arbitrary D spacetime dimensions. Using the N = 2 supersymmetric worldline action, augmented by finite-size corrections for the non-Kerr black hole case, we build a quadratic-in-spin extension to the worldline quantum field theory (WQFT) formalism introduced in our previous work, and calculate the two bodies' deflection and spin kick to sub-leading order in the post-Minkowskian expansion in Newton's constant G. For spins aligned to the normal vector of the scattering plane we also obtain the scattering angle. All D-dimensional observables are derived from an eikonal phase given as the free energy of the WQFT that is invariant under the N = 2 supersymmetry transformations.

Reconstructing Classical Spacetimes from the S-Matrix in Twistor Space

“…It would be interesting to explore this vein for our amplitudes. Indeed, our construction relies on the relation between classical spacetimes and gravitational amplitudes, which has been tested to high loop precision [17,33,50,84,109]. It is a pressing question to understand how non-linear effects interrelate both sides, especially in view that the gravitational field is not free asymptotically in the non-linear theory, which is reflected as an IR dressing in the perturbative theory.…”

Classical Double Copy of Worldline Quantum Field Theory

“…An obvious extension of the classical double copy is to incorporate spin, some attempts in this direction are [10,11,35]. The recently discovered hidden supersymmetry in the worldline description of spinning compact bodies [17] should be applicable to the Yang-Mills case as well. In particular the limitation of coupling higher-spin worldline theories to gravity might be overcome upon using the double copy.…”

“…Returning to the realm of applying quantum field theory based techniques to the post-Minkowskian perturbative gravitational scattering problem, an approach termed worldline quantum field theory (WQFT) was put forward recently [16,17] that explains the relation between the two presently common approaches employing the classical limit of scattering amplitudes, see e.g. [18][19][20][21], and the PM effective field theory (EFT) approach, see e.g.…”

“…In essence it starts out from a first quantized description of the matter field's (scalar, spinor, vector) propagator in a gravitational background à la Feynman-Schwinger and demonstrates how this leads in a classical limit to the effective field theory description. Yet, the WQFT formalism not only is of conceptual relevance (introducing an approximate supersymmetry in the description of spin for black holes and neutron stars [17]), it also provides a very efficient tool to quickly arrive at the classical observables of the scattering process without the need to go through an iterative solution of the equations of motion in the standard EFT approach or to deal with the subtleties of the classical limit in the amplitudes based approach. As such the deflection, the spin-kick or the explicit gravitational Bremsstrahlung waveform as well as the eikonal being the generating function of these have been established at NLO [17,23,24].…”

Gravitational spin-orbit dynamics at the fifth-and-a-half post-Newtonian order

“…Spin effects were included in PM expansions using all these approaches in Refs. [75][76][77][78][79][80][81][82][83][84][85][86][87][88], and radiative contributions in Refs. [89][90][91][92][93].…”