Scattering in black hole backgrounds and higher-spin amplitudes. Part II

Journal Article · Fri May 26 00:00:00 EDT 2023 · Journal of High Energy Physics (Online)

DOI:https://doi.org/10.1007/jhep05(2023)211· OSTI ID:2417690

Bautista, Yilber Fabian ^[1]; Guevara, Alfredo ^[2]; Kavanagh, Chris ^[3]; Vines, Justin ^[4]

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1. Perimeter Inst. for Theoretical Physics, Waterloo, ON (Canada); York Univ., Toronto, ON (Canada); Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA-Saclay), Gif-sur-Yvette (France); Univ. Paris-Saclay, Gif-sur-Yvette (France); Harvard Univ., Cambridge, MA (United States)
2. Harvard Univ., Cambridge, MA (United States); Univ. of California, Santa Barbara, CA (United States). Kavli Institute for Theoretical Physics
3. University College Dublin (Ireland); Max Planck Institute for Gravitational Physics, Potsdam (Germany)
4. Univ. of California, Santa Barbara, CA (United States). Kavli Institute for Theoretical Physics; Max Planck Institute for Gravitational Physics, Potsdam (Germany); Univ. of California, Los Angeles, CA (United States)

We continue to investigate correspondences between, on the one hand, scattering amplitudes for massive higher-spin particles and gravitons in appropriate quantum-to-classical limits, and on the other hand, classical gravitational interactions of spinning black holes according to general relativity. We first construct an ansatz for a gravitational Compton amplitude, at tree level, constrained only by locality, crossing symmetry, unitarity and consistency with the linearized-Kerr 3-point amplitude, to all orders in the black hole’s spin. We then explore the extent to which a unique classical Compton amplitude can be identified by comparing with the results of the classical process of scattering long-wavelength gravitational waves off an exact Kerr black hole, determined by appropriate solutions of the Teukolsky equation. Up to fourth order in spin, we find complete agreement with a previously conjectured exponential form of the tree-level Compton amplitude. At higher orders, we extract tree-level contributions from the Teukolsky amplitude by an analytic continuation from a physical (a/GM < 1) to a particle-like (a/GM > 1) regime. Up to the sixth order in spin, we identify a unique conservative part of the amplitude which is insensitive both to the choice of boundary conditions at the black hole horizon and to branch choices in the analytic continuation. The remainder of the amplitude is determined modulo an overall sign from a branch choice, with the sign flipping under exchanging purely ingoing and purely outgoing boundary conditions at the horizon. Along the way, we make contact with novel applications of massive spinor-helicity variables pertaining to their relation to EFT operators and (spinning) partial amplitudes.

• Research Organization: Harvard Univ., Cambridge, MA (United States)
• Sponsoring Organization: European Research Council (ERC); Science Foundation Ireland (SFI); USDOE Office of Science (SC)
• Grant/Contract Number: SC0007870
• OSTI ID: 2417690
• Journal Information: Journal of High Energy Physics (Online), Journal Name: Journal of High Energy Physics (Online) Journal Issue: 5 Vol. 2023; ISSN 1029-8479
• Publisher: Springer Nature
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
Black Holes
Physics
Scattering Amplitudes