Supersymmetry Relations and MHV Amplitudes in Superstring Theory

Understand

We discuss supersymmetric Ward identities relating various scattering amplitudes in type I open superstring theory.

• We show that at the disk level, the form of such relations remains exactly the same, to all orders in alpha', as in the low-energy effective field theory describing the alpha'-> 0 limit.
• This result holds in D=4 for all compactifications, even for those that break supersymmetry.
• We apply SUSY relations to the computations of N-gluon MHV superstring amplitudes, simplifying the existing results for N<7 and deriving a compact expression for N=7.