1998/04/30 by B. Pioline · 1 citation
Physics and Astronomy · #hep-th
paper · pdf · doi:10.1016/s0370-2693(98)00554-1
published as Phys.Lett. B431 (1998) 73-76 · 6 pages, uses amsmath and amssymb; typo in eq.(2) corrected; final version to be published in Phys. Lett. B
arxiv created 1998/04/30 · arxiv updated 2009/11/30
Exact non-perturbative results have been conjectured for R4 couplings in type II maximally supersymmetric string theory. Strong evidence has already been obtained, but contributions of cusp forms, invisible in perturbation theory, have remained an open possibility. In this note, we use the D=8 N=2 superfield formalism of Berkovits to prove that supersymmetry requires the exact R4 threshold to be an eigenmode of the Laplacian on the scalar manifold with a definite eigenvalue. Supersymmetry and U-duality invariance then identify the exact result with the order-3/2 Eisenstein series, and rule out cusp form contributions.