Two-loop helicity amplitudes for gg ? ZZ with full top-quark mass effects

A bstract We calculate the two-loop QCD corrections to gg ? ZZ involving a closed top-quark loop. present new method systematically construct linear combinations of Feynman integrals with convergent parametric representation, where we also allow for irreducible numerators, higher powers propagators, dimensionally shifted integrals, and subsector integrals. The amplitude is expressed in terms such finite by employing syzygies derived algebra field techniques. Evaluating using numerical integration, find agreement previous expansions asymptotic limits provide ab initio results intermediate partonic energies non-central scattering at energies.