Supersymmetry Relations and MHV Amplitudes in Superstring Theory
arXiv:0708.0574 · doi:10.1016/j.nuclphysb.2007.09.033
Abstract
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.
34 pages, harvmac; v2: 2 figs added; final version to appear in NPB