  Dark matter and cosmic inflation represent two of the major puzzles in
cosmology. They are typically addressed by introducing separate fields with
independent dynamics. On the other hand, extra dimensions might play an
important role for observable physics. We introduce a five-dimensional model
called dark inflaxion that includes an axion-like particle, whose Kaluza-Klein
modes can describe inflation and dark matter. We show that a simple yet natural
choice of the mass scale of the effective four-dimensional fields of our model
can accommodate simultaneously the observable values of inflationary parameters
and dark-matter abundance. It will be interesting to explore the consequences
and predictions of more generic scenarios within the scope of our model, which
include the possibility of multifield inflation and dark matter.
