Two-loop four-graviton scattering amplitudes

Souto Gonçalves de abreu, Samuel [UCL] Febres Cordero, F. [Florida State University] Ita, H. [Albert-Ludwigs-Universität Freiburg] Jaquier, M. [Institute for Theoretical Particle Physics] Page, B. [Université Paris-Saclay] Ruf, M. S. [Albert-Ludwigs-Universität Freiburg] Sotnikov, V. [Max Planck Insitute for Physics] et al.[show all]

We present the analytic form of the two-loop four-graviton scattering amplitudes in Einstein gravity. To remove ultraviolet divergences we include counterterms quadratic and cubic in the Riemann curvature tensor. The two-loop numerical unitarity approach is used to deal with the challenging momentum dependence of the interactions. We exploit the algebraic properties of the integrand of the amplitude in order to reduce it to a minimal basis of Feynman integrals. Analytic expressions are obtained from numerical evaluations of the amplitude. Finally, we show that four-graviton scattering observables depend on fewer couplings than naïvely expected.