  We derive quantum kinetic equations for mixing neutrinos including consistent
forward scattering terms and collision integrals for coherent neutrino states.
In practice, we reduce the general Kadanoff--Baym equations in a few clearly
justified steps to a generalized density matrix equation that describes both
the flavour- and particle-antiparticle coherences and is valid for arbitrary
neutrino masses and kinematics. We then reduce this equation to a simpler
particle-antiparticle diagonal limit and eventually to the ultra-relativistic
limit. Our derivation includes simple Feynman rules for computing collision
integrals with the coherence information. We also expose a novel spectral shell
structure underlying the mixing phenomenon and quantify how the prior
information on the system impacts on the QKE's, leading to a direct effect on
its evolution. Our results can be used for example to accurately model neutrino
distributions in hot and dense environments and to study the production and
decay of mixing heavy neutrinos in colliders.

High Energy Physics - Phenomenology;High Energy Astrophysical Phenomena;High Energy Physics - Theory