  In gauge-Yukawa systems embedded in the framework of trans-Planckian
asymptotic safety we discuss the dynamical generation of arbitrarily small
Yukawa couplings driven by the presence of a non-interactive
infrared-attractive fixed point in the renormalization group flow. Additional
ultraviolet-attractive fixed points guarantee that the theory remains well
defined up to an infinitely high scale. We apply this mechanism to the Yukawa
couplings of the Standard Model extended with right-handed neutrinos, finding
that asymptotically safe solutions in agreement with the current experimental
determination of the masses and mixing angles exist for Dirac neutrinos with
normal mass ordering. We generalize the discussion by applying the same
mechanism to a new-physics model with sterile-neutrino dark matter, where we
generate naturally the feeble Yukawa interaction required to reproduce via
freeze-in the correct relic abundance.
