CoLoRFul for hadron collisions: Integrating the counterterms

TL;DR

The paper addresses infrared divergences in hadron-hadron collision NNLO QCD calculations and extends the CoLoRFul infrared subtraction scheme to this setting. A core contribution is the analytic integration of the complete $A_{12}$ counterterm set, implemented via a pipeline that combines sector decomposition, polynomial factorization with rationalization, a new univariate partial fraction method LinApartChargeishvili, and MPLs via PolyLogTools. The integrated results are implemented in the Fortran code NNLOCAL and validated in gluon fusion Higgs production with $n_f=0$, showing pole cancellation and sub-percent agreement with $n3loxs$ at 13 TeV for several $m_H$ values. This work demonstrates that NNLO predictions for color-singlet production in hadron collisions are within reach and lays the groundwork for extending to full QCD.

Abstract

In order to numerically compute scattering cross sections in QCD, one needs to deal with various kinematic divergences that appear at intermediate stages of the calculation. One way of doing this is by setting up an IR subtraction scheme. In this talk we give an update on the status of extending the CoLoRFul subtraction scheme, which has been successfully used in the past for processes with only final-state hadrons, to hadron-hadron collisions. In particular we discuss the analytic computation of the integrated counterterms.