Supersymmetry Relations and MHV Amplitudes in Superstring Theory

TL;DR

This paper demonstrates that supersymmetric Ward identities in superstring theory remain consistent with low-energy field theory relations at all orders, simplifying calculations of MHV amplitudes across various compactifications.

Contribution

It shows the invariance of supersymmetric relations at all alpha' orders and derives a new compact expression for N=7 gluon MHV amplitudes.

Findings

Supersymmetric Ward identities hold at all alpha' orders.

Simplified calculations for N-gluon MHV amplitudes, especially for N<7.

Derived a compact formula for N=7 MHV amplitudes.

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.