LASS, the numerics

TL;DR

This paper presents a numerical implementation of the Local Analytical Subtraction Scheme (LASS) for NNLO QCD predictions in electron-positron collisions, focusing on regularizing double-real radiation contributions and validating the method through convergence tests.

Contribution

The paper introduces a numerical implementation of LASS for NNLO QCD calculations, demonstrating its effectiveness in regularizing complex radiation contributions and validating the approach with high-precision tests.

Findings

Successful convergence of subtraction terms in various singular limits

Validation of LASS formalism through numerical tests

Application to three-jet production in e+e- collisions

Abstract

We summarize our efforts to create a numerical implementation of the Local Analytical Subtraction Scheme (LASS) for obtaining NNLO QCD predictions in electron-positron collisions. We focus on the regularization of double-real radiation contributions, which are typically the most computationally intensive part of NNLO calculations. We describe the structure of the subtraction terms in LASS and our approach to numerically validate them. Using arbitrary precision arithmetic, we demonstrate the proper convergence of individual subtraction terms, overlap removal terms, and spurious singularity cancellations in various singular limits. We show results for the specific case of three-jet production in $e^+e^-$ collisions. Our results validate the correctness of both the LASS formalism and our numerical implementation, setting the stage for full NNLO calculations using this method.