epsilon: A tool to find a canonical basis of master integrals

In 2013, Henn proposed a special basis for a certain class of master integrals, which are expressible in terms of iterated integrals. In this basis, the master integrals obey a differential equation, where the right hand side is proportional to is an element of in d = 4-2 is an element of space-time dimensions. An algorithmic approach to find such a basis was found by Lee. We present the tool epsilon, an efficient implementation of Lee's algorithm based on the Fermat computer algebra system as computational back end. Program summary Program Title: epsilon Program Files doi: http://dx.doi.org/10.17632/j59sy5n729.1 Licensing provisions: GPLv3 Programming language: C++ Nature of problem: For a certain class of master integrals, a canonical basis can be found in which they fulfill a differential equation with the right hand side proportional to is an element of. In such a basis the solution of the master integrals in an is an element of-expansion becomes trivial. Unfortunately, the problem of finding a canonical basis is challenging. Solution method: Algorithm by Lee [1] Restrictions: The normalization step of Lee's algorithm will fail if the eigenvalues of the matrix residues are not of the form a + b is an element of with a, b is an element of Z. Multi-scale problems are not supported. [1] RN. Lee, JHEP 1504 (2015) 108 [arXiv:1411.0911 [hep-ph]]. (C) 2017 Elsevier B.V. All rights reserved.