Evaluating multi-loop Feynman integrals numerically through differential equations

Abstract

The computation of Feynman integrals is often the bottleneck of multi-loop calculations. We propose and implement a new method to efficiently evaluate such integrals in the physical region through the numerical integration of a suitable set of differential equations, where the initial conditions are provided in the unphysical region via the sector decomposition method. We present numerical results for a set of two-loop integrals, where the non-planar ones complete the master integrals for $gg\to \gamma \gamma$ and $q\bar{q}\to \gamma \gamma$ scattering mediated by the top quark.

Minor changes, accepted version