In this paper, we generalize the unitarity method to two-loop diagrams and use it to discuss the integral bases of reduction. To test out method, we focus on the four-point double-box diagram as well as its related daughter diagrams, i.e., the double-triangle diagram and the triangle-box diagram. For later two kinds of diagrams, we have given complete analytical results in general (4-2\eps)-dimension.
@article{arxiv.1401.6766,
title = {Integral Reduction by Unitarity Method for Two-loop Amplitudes: A Case Study},
author = {Bo Feng and Jun Zhen and Rijun Huang and Kang Zhou},
journal= {arXiv preprint arXiv:1401.6766},
year = {2015}
}