Universality of ultra-relativistic gravitational scattering

By Paolo Di Vecchia, C. Heissenberg, R. Russo, G. Veneziano. Physics Letters B, 2020

158 citations recorded by the source corpus.

We discuss the ultra-relativistic gravitational scattering of two massive particles at two-loop (3PM) level. We find that in this limit the real part of the eikonal, determining the deflection angle, is universal for gravitational theories in the two derivative approximation. This means that, regardless of the number of supersymmetries or the nature of the probes, the result connects smoothly with the massless case discussed since the late eighties by Amati, Ciafaloni and Veneziano. We analyse the problem both by using the analyticity and crossing properties of the scattering amplitudes and, in the case of the maximally supersymmetric theory, by explicit evaluation of the 4-point 2-loop amplitude using the results for the integrals in the full soft region. The first approach shows that the observable we are interested in is determined by the inelastic tree-level amplitude describing the emission of a graviton in the high-energy double-Regge limit, which is the origin of the universality property mentioned above. The second approach strongly suggests that the inclusion of the whole soft region is a necessary (and possibly sufficient) ingredient for recovering ultra relativistic finiteness and universality at the 3PM level. We conjecture that this universality persists at all orders in the PM expansion.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/fff97b8bb1dd59c320a5eb2a2c0ca8bb420a7272

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Citations in the corpus

Radiative contribution to classical gravitational scattering at the third order in G (2020, methodology): “Its validity in GR was recently confirmed [40, 41].”
Radiation reaction from soft theorems (2021, methodology): “In this letter we expand on the approach discussed in [28,34] where the relation between the real and the imaginary part of δ2 was used to derive the 3PM scattering angle in the ultrarelativistic limit and to show that it is a universal feature of all gravitational theories in the two derivative app”