Exact flow equation for composite operators

We propose an exact flow equation for composite operators and their correlation functions. This can be used for a scale-dependent partial bosonization or flowing bosonization of fermionic interactions, or for an effective change of degrees of freedom in dependence on the momentum scale. The flow keeps track of the scale dependent relation between effective composite fields and corresponding composite operators in terms of the fundamental fields. (C) 2009 Elsevier B.V. All rights reserved.