Conformal Portal to Dark Matter
  We propose a new portal coupling to dark matter by taking advantage of the
nonminimally coupled portal sector to the Ricci scalar. Such a portal sector
conformally induces couplings to the trace of the energy-momentum tensor of
matters including highly secluded dark matter particles. The portal coupling is
so feeble that dark matter is produced by freeze-in processes of scatterings
and/or the decay of the mediator. We consider two concrete realizations of the
portal: conformally induced Higgs portal and conformally induced mediator
portal. The former case is compatible with the Higgs inflation, while the
latter case can be tested by dark matter direct detection experiments.
