Higher-order Corrections to Top-antitop Pair and Single Top Quark Production

The top quark plays an important role in the Standard Model of particle physics as the most massive elementary particle, relevant to electroweak physics. The top was discovered via pair production [1, 2] and has also been more recently produced via single top [3, 4] channels at the Tevatron. On the theoretical side, QCD corrections are significant for top quark production and even higherorder corrections are not negligible. An important class of corrections are contributions from soft-gluon emission, of the form ln(s4/m )/s4, with s4 a variable that measures distance from threshold. Softgluon corrections are dominant near threshold and can be resummed. Resummation at NLL (NNLL) accuracy requires one-loop (two-loop [5]) calculations in the eikonal approximation. Approximate higherorder (NNLO or NNNLO) cross sections can be derived from the expansion of the resummed cross section [6, 7, 8, 9, 10]. We perform the resummation and higher-order expansions at the differential level. In contrast to simple resummation calculations that apply only to the total cross section and which involve additional approximations for the kinematics, our fully differential calculations have sensitivity to the exact kinematics and allow not only total cross section calculations but also differential pT and other distributions.