Light fermionic NNLO QCD corrections to top-antitop production in the quark-antiquark channel

TL;DR

This paper calculates the light fermionic NNLO QCD corrections to top-antitop production in the quark-antiquark channel, validating the antenna subtraction method and providing a Monte Carlo generator for detailed differential distributions.

Contribution

It introduces the computation of real-virtual and virtual-virtual NNLO corrections for top pair production using antenna subtraction, extending the formalism to massive quarks.

Findings

Infrared poles cancel at all levels, confirming the subtraction method's validity.

Implemented NNLO corrections in a Monte Carlo generator for detailed event analysis.

Provided differential distributions for top-antitop production at NNLO.

Abstract

We present the NNLO corrections to top pair production in the quark-antiquark channel proportional to the number of light quark flavors $N_l$. While the double real corrections were derived previously, here we compute the real-virtual and virtual-virtual contributions in this partonic channel. Using the antenna subtraction formalism, we show that the subtraction terms correctly approximate the real-virtual contributions in all their infrared limits. Combined with the integrated forms of the double real and real-virtual subtraction terms, we show analytically that the explicit infrared poles cancel at the real-virtual and virtual-virtual levels respectively, thereby demonstrating the validity of the massive extension of the NNLO antenna formalism. These NNLO corrections are implemented in a Monte Carlo parton level generator providing full kinematical information on an event-by event basis. With this program, NNLO differential distributions in the form of binned histograms are obtained and presented here.