We apply a bootstrap procedure to two-loop MHV amplitudes in planar N=4 super-Yang-Mills theory. We argue that the mathematically most complicated part (the Λ2B2 coproduct component) of the n-particle amplitude is uniquely determined by a simple cluster algebra property together with a few physical constraints (dihedral symmetry, analytic structure, supersymmetry, and well-defined collinear limits). We present a concise, closed-form expression which manifests these properties for all n.
@article{arxiv.1411.3289,
title = {A Cluster Bootstrap for Two-Loop MHV Amplitudes},
author = {John Golden and Marcus Spradlin},
journal= {arXiv preprint arXiv:1411.3289},
year = {2015}
}