Self-Interacting Dark Matter with Flavor Mixing
  The crisis of both cold and collisional dark matter (DM) models is resolved by postulating flavor mixing of DM particles. Flavor-mixed particles segregate in the gravitational field to form dark halos composed of heavy mass eigenstates. Since these particles are mixed in the interaction basis, elastic collisions convert some of heavy eigenstates into light ones which leave the halo. This annihilation-like process will soften dense central cusps of halos. The proposed model accumulates most of the attractive features of self-interacting and annihilating DM models, but does not suffer from their severe drawbacks. This model is natural does not require fine tuning. 
Mikhail V. Medvedev (CITA)