Antenna subtraction at NNLO for heavy quark pair production at hadron colliders: the non-diagonal channels

Abstract

We present the calculation involving the $qq$, $qq'$ and $qg$ partonic channels contributing to heavy-quark pair production at hadron colliders through next-to-next-to-leading order in QCD using the antenna subtraction formalism. The calculation is performed in full colour and implemented within the NNLOJET framework. Building upon previously available results, we complete the NNLO treatment of the $qq$ and $qq'$ channels by deriving the integrated subtraction contributions required at the real virtual and double-virtual levels. We further present for the first time the NNLO antenna subtraction terms related to the $qg$-channel in full colour. The calculation requires several new ingredients, including massive soft factors and convolutions involving integrated massive antennae thereby extending the integrated antenna library to cope with processes with massive fermions. We validate the calculation through analytic infrared pole cancellation and numerical comparisons with existing results. These results complete the NNLO description of the $qq$, $qq'$, and $qg$ channels and constitute an important step towards a fully differential NNLO treatment of heavy-quark pair production within the antenna subtraction formalism.