Complete Nagy-Soper subtraction for next-to-leading order calculations in QCD

TL;DR

This paper introduces a new subtraction formalism integrated into Helac-Dipoles for more accurate next-to-leading order QCD calculations involving arbitrary parton masses and multiplicities, improving computational efficiency and flexibility.

Contribution

It extends the Helac-Dipoles package with a systematic semi-numerical subtraction scheme based on Nagy and Soper's formalism, enabling complete NLO QCD calculations for complex processes.

Findings

The new scheme accurately reproduces known results with Catani-Seymour subtraction.

It efficiently handles processes with massive and massless partons.

Random polarization and color sampling improve computational performance.

Abstract

We extend the Helac-Dipoles package with the implementation of a new subtraction formalism, first introduced by Nagy and Soper in the formulation of an improved parton shower. We discuss a systematic, semi-numerical approach for the evaluation of the integrated subtraction terms for both massless and massive partons, which provides the missing ingredient for a complete implementation. In consequence, the new scheme can now be used as part of a complete NLO QCD calculation for processes with arbitrary parton masses and multiplicities. We assess its overall performance through a detailed comparison with results based on Catani-Seymour subtraction. The importance of random polarization and color sampling of the external partons is also examined.