Threshold expansion at order alpha_s^4 for the t-tbar invariant mass distribution at hadron colliders

TL;DR

This paper computes the dominant NNLO QCD corrections to the top-antitop invariant mass distribution at hadron colliders, improving theoretical precision and reducing uncertainties in predictions.

Contribution

It provides the first calculation of the leading alpha_s^4 contributions near the threshold, including all singular terms and scale-dependent logarithms for top pair production.

Findings

NNLO corrections significantly increase the cross section.

Scale uncertainties are notably reduced at NNLO.

Results improve the theoretical accuracy of top pair invariant mass predictions.

Abstract

We calculate the leading O(alpha_s^4) contributions to the invariant mass distribution of top-quark pairs produced at the Tevatron and LHC, in the limit where the invariant mass of the t-tbar pair approaches the partonic center-of-mass energy. Our results determine at NNLO in alpha_s the coefficients of all singular plus distributions and scale-dependent logarithms in the differential partonic cross sections for q-qbar, gg -> t-tbar + X. A numerical analysis showing the effects of the NNLO corrections on the central values and scale dependence of the invariant mass distribution is performed. The NNLO corrections are found to significantly enhance the cross section and reduce the perturbative uncertainties compared to the NLO calculation.