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.

Reference: arXiv:1604.00324