Four-dimensional unsubtraction with massive particles

TL;DR

This paper extends the four-dimensional unsubtraction method based on loop-tree duality to processes with massive particles, enabling NLO corrections to be computed directly in four dimensions, including quasi-collinear configurations.

Contribution

It introduces a generalized momentum mapping for massive particles that ensures a smooth massless limit and demonstrates the method with scalar and vector boson decay examples.

Findings

Method successfully handles heavy particles in NLO calculations.

The approach maintains a smooth massless limit.

Applicable to a wide range of multipartonic processes.

Abstract

We extend the four-dimensional unsubtraction method, which is based on the loop-tree duality (LTD), to deal with processes involving heavy particles. The method allows to perform the summation over degenerate IR configurations directly at integrand level in such a way that NLO corrections can be implemented directly in four space-time dimensions. We define a general momentum mapping between the real and virtual kinematics that accounts properly for the quasi-collinear configurations, and leads to an smooth massless limit. We illustrate the method first with an scalar toy example, and then analyse the case of the decay of a scalar or vector boson into a pair of massive quarks. The results presented in this paper are suitable for the application of the method to any multipartonic process.