A strongly interacting SU(2) pure gauge theory and the nature of light

We present quantitative and qualitative arguments in favor of the claim that, within the present cosmological epoch, the U(1)$_Y$ factor in the Standard Model is an effective manifestation of SU(2) pure gauge dynamics of Yang-Mills scale $\Lambda\sim 10^{-4}$ eV. Results for the pressure and the energy density in the deconfining phase of this theory, obtained in a nonperturbative and analytical way, support this connection in view of large-angle features inherent in the map of the CMB temperature fluctuations and temperature-polarization cross correlations.