Leading-logarithmic threshold resummation of the Drell-Yan process at next-to-leading power

We resum the leading logarithms α _s ⁿ ln ^{2n − 1} (1 − z), n = 1, 2,.. near the kine-matic threshold z = Q ² /ŝ → 1 of the Drell-Yan process at next-to-leading power in the expansion in (1 − z). The derivation of this result employs soft-collinear effective theory in position space and the anomalous dimensions of subleading-power soft functions, which are computed. Expansion of the resummed result leads to the leading logarithms at fixed loop order, in agreement with exact results at NLO and NNLO and predictions from the physical evolution kernel at N ³ LO and N ⁴ LO, and to new results at the five-loop order and beyond.