All-Helicity Symbol Alphabets from Unwound Amplituhedra
arXiv:1711.11507 · doi:10.1007/JHEP05(2018)159
Abstract
We review an algorithm for determining the branch points of general amplitudes in planar $\mathcal{N}=4$ super-Yang-Mills theory from amplituhedra. We demonstrate how to use the recent reformulation of amplituhedra in terms of `sign flips' in order to streamline the application of this algorithm to amplitudes of any helicity. In this way we recover the known branch points of all one-loop amplitudes, and we find an `emergent positivity' on boundaries of amplituhedra.
38 pages, 5 figures, 1 big table; v2: minor corrections and improvements