Overthepastdecade, the?owequationmethodhasdevelopedintoanewv- satile theoretical approach to quantum many-body physics. Its basic concept was conceived independently by Wegner 1] and by G lazek and Wilson 2, 3]: the derivation of a unitary ?ow that makes a many-particle Hamiltonian - creasingly energy-diagonal. This concept can be seen as a generalization of theconventionalscalingapproachesinmany-bodyphysics, wheresomeult- violet energy scale is lowered down to the experimentally relevant low-energy scale 4]. The main di?erence between the conventional scaling approach and the ?ow equation...

Overthepastdecade, the?owequationmethodhasdevelopedintoanewv- satile theoretical approach to quantum many-body physics. Its basic concept was conceived independently by Wegner 1] and by G lazek and Wilson 2, 3]: the derivation of a unitary ?ow that makes a many-particle Hamiltonian - creasingly energy-diagonal. This concept can be seen as a generalization of theconventionalscalingapproachesinmany-bodyphysics, wheresomeult- violet energy scale is lowered down to the experimentally relevant low-energy scale 4]. The main di?erence between the conventional scaling approach and the ?ow equation...