A Grassmannian Etude in NMHV Minors

Understand

Arkani-Hamed, Cachazo, Cheung and Kaplan have proposed a Grassmannian formulation for the S-matrix of N=4 Yang-Mills as an integral over link variables.

• In parallel work, the connected prescription for computing tree amplitudes in Witten's twistor string theory has also been written in terms of link variables.
• In this paper we extend the six- and seven-point results of arXiv:0909.0229 and arXiv:0909.0499 by providing a simple analytic proof of the equivalence between the two formulas for all tree-level NMHV superamplitudes.
• Also we note that a simple deformation of the connected prescription integrand gives directly the ACCK Grassmannian integrand in the limit when the deformation parameters equal zero.