BSM

Abstract

Maximally supersymmetric string theory compactified on d-dimensional torus is invariant under the non-perturbative U-duality groups E_{d+1}(Z). We will present the construction of the automorphic functions relevant for the supersymmetric protected BPS interactions in the low-energy expansion of maximal supersymmetric effective action in various dimensions. We will show that the support of the non-vanishing Fourier coefficients for these automorphic form is given by the expected BPS conditions one can derive from the supersymmetric conditions.