The top-quark jet function and its mass

Far above threshold the production process e+e- → t t can be analyzed using effective field theories. In this paper we consider the invariant-mass distribution of top-jets and report about our computation of the two-loop heavy-quark jet-function. This is a key part of a next-to-next-to-leading order analysis, and already allows for a resummation of all large logs which effect the shape of the top-invariant-mass distribution at next-to-next-to-leading log order. A top-mass scheme is defined which is suitable for measurements involving jets, and whose anomalous dimension is determined by the cusp-anomalous dimension to all orders in perturbation theory.