Numerical evaluation of six-photon amplitudes

Abstract

We apply the recently proposed amplitude reduction at the integrand level method, to the computation of the scattering process 2γ 4γ, including the case of a massive fermion loop. We also present several improvements of the method, including a general strategy to reconstruct the rational part of any one-loop amplitude and the treatment of vanishing Gram-determinants. © SISSA 2007.