  We study a novel proposal for the origin of cosmological cold dark matter
(CDM) which is rooted in the quantum nature of spacetime. In this model,
off-shell modes of quantum fields can exist in asymptotic states as a result of
spacetime nonlocality (expected in generic theories of quantum gravity), and
play the role of CDM, which we dub off-shell dark matter (OfDM). However, their
rate of production is suppressed by the scale of non-locality (e.g. Planck
length). As a result, we show that OfDM is only produced in the first moments
of big bang, and then effectively decouples (except through its gravitational
interactions). We examine the observational predictions of this model: In the
context of cosmic inflation, we show that this proposal relates the reheating
temperature to the inflaton mass, which narrows down the uncertainty in the
number of e-foldings of specific inflationary scenarios. We also demonstrate
that OfDM is indeed cold, and discuss potentially observable signatures on
small scale matter power spectrum.
