Double-real radiation in hadronic top quark pair production as a proof of a certain concept

TL;DR

This paper applies the STRIPPER method to compute next-to-next-to-leading order cross sections for top quark pair production in hadronic collisions, demonstrating its convergence and divergence cancellation.

Contribution

It introduces the use of the STRIPPER approach for double-real radiation in top quark production, extending double-soft current formulas to massive partons.

Findings

Successful evaluation of total cross sections for key partonic channels

Demonstration of pointwise convergence and computational efficiency

Proof of divergence cancellation after including virtual contributions

Abstract

Using the recently introduced STRIPPER approach to double-real radiation, we evaluate the total cross sections for the main partonic channels of the next-to-next-to leading order contributions to top quark pair production in hadronic collisions: gg -> ttgg, gg -> ttqq, qq -> ttgg, qq -> ttq'q', q' != q. The results are given as Laurent expansions in epsilon, the parameter of dimensional regularization, at a number of m/ECM values spreading the entire variation range, with m the mass of the top quark and ECM the center-of-mass energy. We describe the details of our implementation and demonstrate its main properties: pointwise convergence and efficiency. We also prove the cancellation of leading divergences after inclusion of the double-virtual and real-virtual contributions. On a more technical note, we extended the double-soft current formulae to the case of massive partons.