Structure functions in semihadronic tau decays

We review a variety of topics related to hadronic structure functions in exclusive semihadronic tau decays. We introduce the concept of structure functions and summarize the most important concepts. We then calculate the decay τ→3πντ for very small hadronic invariant mass to one loop in chiral perturbation theory. New interesting features emerge with respect to the known results at tree level, in particular for the structure functions wD and wE. We discuss the prospects for experimental verification of our predictions. Finally, we discuss various issues at higher Q2, related to hadronic resonance physics. Here we consider 2π, πK, 3π, KπK and πKπ hadronic final states. (orig.)