Speaker: Dr. Max Zoller
Affiliation: PSI, Switzerland
Title: Two-loop tensor integral coefficients in OpenLoops
Abstract: The development of a fully automated tool for the numerical calculation of NNLO corrections to scattering amplitudes is a highly desirable goal for the LHC era. Two-loop amplitudes can be expressed in terms of tensor integrals over two loop momenta with coefficients derived from the Feynman diagrams of a given scattering process. Hence, the calculation can be structured into the computation of the tensor coefficients, the reduction of the tensor integrals and the evaluation of the resulting master integrals.
In this talk, we present a new algorithm to numerically construct the tensor coefficients for two-loop amplitudes in the OpenLoops framework. Exploiting the factorisation of Feynman diagrams into universal building blocks, we construct these coefficients in a highly efficient way. The algorithm is completely general and has been fully implemented and tested for QED and QCD corrections to the Standard Model. We will discuss the structure of the algorithm and present studies on its CPU efficiency and numerical stability.