Interacting dark sector with transversal interaction
  We investigate the interacting dark sector composed of dark matter, dark
energy, and dark radiation for a spatially flat Friedmann-Robertson-Walker
(FRW) background by introducing a three-dimensional internal space spanned by
the interaction vector $\mathbf{Q}$ and solve the source equation for a linear
transversal interaction. Then, we explore a realistic model with dark matter
coupled to a scalar field plus a decoupled radiation term, analyze the amount
of dark energy in the radiation era and find that our model is consistent with
the recent measurements of cosmic microwave background anisotropy coming from
Planck along with the future constraints achievable by CMBPol experiment.
