competing instabilities of the system can be treated on equal footing and thereby channel interference can be studied within this framework. However, within the RG scheme, the phase transition is approached coming from high energies, allowing us to determine the leading instability of the system, but this approach is less suited to explore the ordered state further. For example, the model defined by the Hamiltonian $\mathcal{H}=\mathcal{H}_0+\mathcal{H}_\mathrm{int}$ as stated in Eqs.  and  is in principle also unstable towards the formation of superconductivity, which is expected to interfere with SDW ordering.

In fact, the complex phase diagrams of materials of current interest such as the iron-based superconductors can be understood as a result of the interplay of different competing instabilities: Already the simple two-band model allows for superconductivity as well as SDW order and CDW order [@ChubukovEfremovEremin-PRB2008; @PodolskyKeeKim-EPL2009; @KangTesanovic-PRB2011], owing to the nested nature of the Fermi surface. This model is essentially a band-basis translation of the model investigated in this paper. Hence the calculation of fluctuation corrections to the corresponding zero-temperature gap equations is straightforward, see Appendix \[app:calculation\]. What is more, we can use the RG equations derived for the same model [@ChubukovEfremovEremin-PRB2008] to analyze the effect of channel interference on 