Reduction of planar double-box diagram for single-top production via auxiliary mass flow

TL;DR

This paper enhances the auxiliary mass flow method with epsilon truncation to efficiently reduce complex NNLO amplitudes in single-top production, demonstrated on a planar double-box diagram relevant to LHC physics.

Contribution

The paper introduces an improved AMF method with epsilon truncation for systematic reduction of NNLO amplitudes in single-top production.

Findings

Coefficient reduction to 198 scalar integrals

Effective demonstration on a planar double-box diagram

Potential for more efficient NNLO calculations in collider physics

Abstract

The single-top production is an important process at the LHC to test the Standard Model (SM) and search for the new physics beyond the SM. Although the complete next-to-next-to-leading order (NNLO) QCD correction to the single-top production is crucial, this calculation is still challenging at present. In order to efficiently reduce the NNLO single-top amplitude, we improve the auxiliary mass flow (AMF) method by introducing the $\epsilon$ truncation. For demonstration we choose one typical planar double-box diagram for the $tW$ production. It is shown that one coefficient of the form factors on its amplitude can be systematically reduced into the linear combination of 198 scalar integrals.