On the NNLO QCD corrections to single-top production at the LHC
  We present a fully-differential calculation of the NNLO QCD corrections to the t-channel mechanism for producing single top quarks at the LHC. We work in the structure function approximation, computing QCD corrections to the light- and heavy-quark lines separately and neglecting the dynamical cross-talk between the two. The neglected contribution, which appears at NNLO for the first time, is color-suppressed and is expected to be sub-dominant. Within this approximation, we find that, for the total cross section, NNLO QCD corrections are in the few percent range and, therefore, are comparable to NLO QCD corrections. We also find that the scale independence of the theoretical prediction for single-top production improves significantly once NNLO QCD corrections are included. Furthermore, we show how these results change if a cut on the transverse momentum of the top quark is applied and derive the NNLO QCD prediction for the ratio of single top and single anti-top production cross sections at the 8 TeV LHC. 
Mathias Brucherseifer, Fabrizio Caola and Kirill Melnikov
hep-ph