Resummation of non-global QCD observables

We discuss issues related to the resummation of non-global observables in QCD, those that are sensitive to radiation in only a part of phase space. Examples of such observables are certain single-hemisphere event shapes in e+e− and DIS. Compared to global observables (those sensitive to all emissions, e.g., the e+e− thrust) a new class of single-logarithmic terms arises. These have been neglected in recent calculations in the literature. For a whole set of single hemisphere e+e− and DIS event shapes, we analytically evaluate the first such term, at order αs2, and give numerical results for the resummation of these terms in the large-NC limit.