Massive planar and non-planar double box integrals for light Nf contributions to gg->tt

Understand

We present the master integrals needed for the light fermionic two-loop corrections to top quark pair production in the gluon fusion channel.

• Via the method of differential equations we compute the results in terms of multiple polylogarithms in a Laurent series about d=4, where d is the space-time dimension.
• The most involved topology is a non-planar double box with one internal mass.
• We employ the coproduct-augmented symbol calculus and show that significant simplifications are possible for selected results using an optimised set of multiple polylogarithms.