This past year a team at IPhT around John Joseph Carrasco — in collaboration with physicists at UCLA and Penn State University in the United States, and Uppsala University in Sweden — completed a calculation long thought to be impossible: the direct understanding of the dimensions of spacetime in which the most symmetric particlebased field theory of gravity (maximal supergravity) would cease to be predictive when quantum effects are relevant. One can isolate order by order the quantum effects in graviton scattering. For two gravitons scattering off of each other, this calculation required consideration of the fifthorder quantum correction. This puts strong constraints on the behavior of fundamental symmetries in controlling the highenergy behavior of this theory. To carry out this calculation, they instead relied critically on newfound insights as to the local relationship of gravity to the theory that describes how quarks interact via gluons. This is called Double Copy structure. If you successfully carry out a calculation involving gluons, it turns out you can recycle it to make a prediction involving gravitons. Using these ideas effectively turned the impossibly complicated gravity calculation into a much tamer one: a few tens of thousands of expressions. This is less than the number of unique words in the French language! This approach has yielded insights that may prove crucial to the ultimate all order understanding of our ability to make quantum gravity predictions in particle field theory. The very precise form of the double copy structure fits perfectly with the algebraic structures derived from elementary properties of quantum field theory amplitudes. This work of course does not happen in a vacuum. The field of studying scattering between fundamental particles  the study of scattering amplitudes  has seen tremendous progress over the past decades, and the work here builds upon developments pioneered by other members of IPhT, including that of David Kosower, Gregory Korchemsky, and Pierre Vanhove.
[1] Ultraviolet Properties of N=8 Supergravity at Five Loops [2] Fiveloop fourpoint integrand of N=8 supergravity as a generalized double copy [3] Gravity Amplitudes as Generalized Double Copies of GaugeTheory Amplitudes
[4] Dual superconformal symmetry of scattering amplitudes in N=4 superYangMills theory [5] Fusing gauge theory tree amplitudes into loop amplitudes [6] Monodromy and JacobiLike Relations for ColorOrdered Amplitudes, [7] The Critical Ultraviolet Behaviour of N=8 Supergravity Amplitudes, P. Vanhove, 

C. Pepin, 20181218
