Non-factorisable contribution to $t$-channel single-top production

TL;DR

This paper calculates the first non-factorisable NNLO QCD corrections to t-channel single-top production at the LHC, revealing a small but notable impact on cross sections and distributions.

Contribution

It introduces the computation of non-factorisable ${ m O}(\a_s^2)$ corrections, a novel aspect at NNLO in perturbative QCD for this process.

Findings

Corrections alter the cross section by about 0.5%.

Kinematic distributions are affected similarly.

First calculation of these corrections at this order.

Abstract

We compute the non-factorisable ${\cal O}(\alpha_s^2)$ corrections to $t$-channel single-top quark production at the LHC. These peculiar corrections arise because of interactions between the heavy- and the light-quark lines and appear for the very first time at next-to-next-to-leading order in perturbative QCD. We find that the non-factorisable corrections change the single-top production cross section and the relevant kinematic distributions in this process by about half a percent.