Light-like Scattering in Quantum Gravity

N. E. J. Bjerrum-Bohr (1) , John F. Donoghue (2) , Barry R. Holstein (3, 2) , Ludovic Plante (4) , Pierre Vanhove (4)

1 NBI - Niels Bohr Institute [Copenhagen]
2 Department of Physics [Amherst]
3 KITP - Kavli Institute for Theoretical Physics [Santa Barbara]
4 IPHT - Institut de Physique Théorique - UMR CNRS 3681

We consider scattering in quantum gravity and derive long-range classical and quantum contributions to the scattering of light-like bosons and fermions (spin-0, spin-1/2, spin-1) from an external massive scalar field, such as the Sun or a black hole. This is achieved by treating general relativity as an effective field theory and identifying the non-analytic pieces of the one-loop gravitational scattering amplitude. It is emphasized throughout the paper how modern amplitude techniques, involving spinor-helicity variables, unitarity, and squaring relations in gravity enable much simplified computations. We directly verify, as predicted by general relativity, that all classical effects in our computation are universal (in the context of matter type and statistics). Using an eikonal procedure we confirm the post-Newtonian general relativity correction for light-like bending around large stellar objects. We also comment on treating effects from quantum hbar dependent terms using the same eikonal method.

Domains: General Relativity and Quantum Cosmology [gr-qc]; High Energy Physics - Theory [hep-th]

N. E. J. Bjerrum-Bohr, John F. Donoghue, Barry R. Holstein, Ludovic Plante, Pierre Vanhove. Light-like Scattering in Quantum Gravity. Journal of High Energy Physics, 2016, 2016 (11), pp.117. ⟨10.1007/JHEP11(2016)117⟩. ⟨cea-01459285⟩