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

We compute the non-factorisable 𝒪 ( α_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.