The NNLO QCD soft function for 1-jettiness

TL;DR

This paper computes the NNLO QCD soft function for 1-jettiness, providing essential numerical results for high-precision collider physics calculations involving jet observables.

Contribution

It presents the first calculation of the non-Abelian part of the 1-jettiness soft function at NNLO using sector decomposition, with detailed numerical fits for LHC and generic kinematics.

Findings

Numerical fits of the soft function for LHC kinematics.

Results applicable to NNLO calculations with N-jettiness.

Detailed sector-decomposition method implementation.

Abstract

We calculate the soft function for the global event variable 1-jettiness at next-to-next-to-leading order (NNLO) in QCD. We focus specifically on the non-Abelian contribution, which, unlike the Abelian part, is not determined by the next-to-leading order result. The calculation uses the known general forms for the emission of one and two soft partons and is performed using a sector-decomposition method that is spelled out in detail. Results are presented in the form of numerical fits to the 1-jettiness soft function for LHC kinematics (as a function of the angle between the incoming beams and the final-state jet) and for generic kinematics (as a function of three independent angles). These fits represent one of the needed ingredients for NNLO calculations that use the N-jettiness event variable to handle infrared singularities.