We discuss the leading-logarithmic power corrections in the N-jettiness
subtraction scheme for higher-order perturbative QCD calculations. We compute
the next-to-leading order power corrections for an arbitrary N-jet process,
and we explicitly calculate the power correction through
next-to-next-to-leading order for color-singlet production for both qqˉ
and gg initiated processes. Our results are compact and simple to implement
numerically. Including the leading power correction in the N-jettiness
subtraction scheme substantially improves its numerical efficiency. We discuss
what features of our techniques extend to processes containing final-state
jets.Comment: 15 pages, 4 figures, references added, version to appear in JHE