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Title:
Type I/Heterotic Duality and M-theory amplitudes
Speaker:
Abstract:
Almost twenty years ago, Horava and Witten considered M theory on an orbifold and elucidated the interrelationships between various theories with ten-dimensional N = 1 supersymmetry. In this talk we will consider a variety of tree level and one loop Feynman diagrams describing four graviton and four gluon amplitude in eleven-dimensional supergravity in a Horava–Witten background compactified on a circle. The goal will be to investigate the relationships between the same amplitudes in the E8 × E8 and SO(32) heterotic string theories and the type I and type IA superstring theories. We will see that the M theory amplitudes accounts for a number of perturbative and non-perturbative aspects of low order higher derivative terms in the low energy expansion of string theory amplitudes, which are expected to be protected by half maximal supersymmetry from receiving corrections beyond one or two loops. We will also discuss the manner in which type I/heterotic duality may be realized for certain higher derivative interactions that are not so obviously protected. For example, our considerations suggest that t8t8R4might receive no loop corrections beyond one loop. For this to be consistent with type I/heterotic duality, D-instanton contributions in the type I SO(32) theory and in the heterotic Spin(32)/Z2 theory appear to play an essential role.
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