Effects of electrically charged dark matter on cosmic microwave
  background anisotropies
  We examine the possibility that dark matter consists of charged massive
particles (CHAMPs) in view of the cosmic microwave background (CMB)
anisotropies. The evolution of cosmological perturbations of CHAMP with other
components is followed in a self-consistent manner, without assuming that CHAMP
and baryons are tightly coupled. We incorporate for the first time the "kinetic
re-coupling" of the Coulomb scattering, which is characteristic of heavy
CHAMPs. By a direct comparison of the predicted CMB temperature/polarization
auto-correlations in CHAMP models and the observed spectra in the Planck
mission, we show that CHAMPs leave sizable effects on CMB spectra if they are
lighter than $10^{11}\,{\rm GeV}$. Our result can be applicable to any CHAMP as
long as its lifetime is much longer than the cosmic time at the recombination
($\sim 4 \times 10^{5}\, {\rm yr}$). An application to millicharged particles
is also discussed.
