We provide two derivations of the one-loop dual conformal anomaly of generic n-point superamplitudes in maximally supersymmetric Yang-Mills theory. Our proofs are based on simple applications of unitarity, and the known analytic properties of the amplitudes.
@article{arxiv.0906.3552,
title = {Proof of the Dual Conformal Anomaly of One-Loop Amplitudes in N=4 SYM},
author = {Andreas Brandhuber and Paul Heslop and Gabriele Travaglini},
journal= {arXiv preprint arXiv:0906.3552},
year = {2009}
}