  We introduce the mono-neutrino signal at neutrino detectors as a smoking gun
of sub-GeV scale dark matter candidates that mainly interact with standard
model neutrinos. In a mono-neutrino process, invisible particles, either dark
matter themselves or the mediator particle, are radiated off a neutrino when it
undergoes the charged-current weak interaction. The associated signals include
a missing transverse momentum with respect to the incoming neutrino beam
direction and the production of wrong-sign charged leptons. We demonstrate the
potential leading role of the future DUNE experiment, using its proposed liquid
and gas argon near detectors, in probing these new signals and the thermal
origins of neutrinophilic dark matter.
