[en] Mildly mixed coupled models include massive ν's and CDM-DE coupling. We present new tests of their likelihood vs. recent data including WMAP7, confirming it to exceed ΛCDM, although at ∼2--σ's. We then show the impact on the physics of the dark components of ν-mass detection in ³H β-decay or 0νββ-decay experiments.

[en] When cosmic microwave background data are used to derive cosmological parameters, their very choice does matter: some parameter values can be biased if the parameter space does not cover the 'true' model. This is a problem because of the difficulty in parameterizing dark energy (DE) physics. We test this risk through numerical experiments. We create artificial data for dynamical or coupled DE models and then use Monte Carlo Markov Chain techniques to recover model parameters by assuming a constant DE state parameter w and no DM-DE coupling. For the DE potential considered, no serious bias arises when coupling is absent. In contrast, ω _o,c and thence H_o and Ω _o,m suffer a serious bias when the 'true' cosmology includes even just a mild DM-DE coupling. Until the nature of the dark components remains unknown, it can be important to allow for a degree of freedom accounting for DM-DE coupling, even more than increasing the number of parameters accounting for the w(a) behavior.