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

摘要

We present the master integrals needed for the light fermionic two-loopcorrections to top quark pair production in the gluon fusion channel. Via themethod of differential equations we compute the results in terms of multiplepolylogarithms in a Laurent series about d=4, where d is the space-timedimension. The most involved topology is a non-planar double box with oneinternal mass. We employ the coproduct-augmented symbol calculus and show thatsignificant simplifications are possible for selected results using anoptimised set of multiple polylogarithms.