  The accumulated energy density of the excited entropy modes in multiple field
inflationary scenarios can play the role of dark matter. In the usual case of a
flat field space without any turning trajectory, only light superhorizon
entropy modes can be excited through the gravitational instability. In the case
of a negatively curved field space, we show that subhorizon entropy modes can
be excited as well through the tachyonic instability induced by the negative
curvature of the field space. The latter allows for production of entropy modes
with masses larger than or at the order of the Hubble expansion rate during
inflation, leading to a new dark matter scenario. Due to the contribution of
subhorizon modes, the corresponding spectral density has a peak at a scale
smaller than its counterpart in the models based on a flat field space. This
difference makes our model observationally distinguishable.
