An Update on Perturbative N=8 Supergravity

Abstract

According to the recent pure spinor analysis of the UV divergences by Karlsson, there are no divergent 1PI structures beyond 6 loops in D=4 N=8 supergravity. In combination with the common expectation that the UV divergences do not appear at less than 7 loops, this may imply that the 4-point amplitude in D=4 N=8 supergravity is all-loop finite. This differs from the result of the previous studies of pure spinors, which suggested that there is a UV divergence at 7 loops in D=4. Therefore an independent investigation of the pure spinor formalism predictions is desirable, as well as continuation of explicit loop computations. In the meantime, we revisit here our earlier arguments on UV finiteness of N=8 supergravity based on the absence of the off-shell light-cone superspace counterterms, as well as on the E_{7(7)} current conservation. We believe that both arguments remain valid in view of the developments in this area during the last few years.