Zero-jettiness resummation for top-quark pair production at the LHC

We study the resummation of the 0-jettiness resolution variable tau(0) for the top-quark pair production process in hadronic collisions. Starting from an effective theory framework we derive a factorisation formula for this observable which allows its resummation at any logarithmic order in the tau(0) -> 0 limit. We then calculate the O(alpha(s)) corrections to the soft function matrices and, by employing renormalisation group equation methods, we obtain the ingredients for the resummation formula up to next-to-next-to-leading logarithmic (NNLL) accuracy. We study the impact of these corrections to the 0-jettiness distribution by comparing predictions at different accuracy orders: NLL, NLL', NNLL and approximate NNLL' (NNLL'(a)). We match these results to the corresponding fixed order calculations both at leading order and next-to-leading order for the t (t) over bar +jet production process, obtaining the most accurate prediction of the 0-jettiness distribution for the top-quark pair production process at NNLL'(a) +NLO accuracy.