  In this paper we have recalled the semiclassical metric obtained from a
classical analysis of the loop quantum black hole (LQBH). We show that the
regular Reissner-Nordstr\"om-like metric is self-dual in the sense of
T-duality: the form of the metric is invariant under the exchange r -> a0/r
where a0 is proportional to the minimum area in LQG. Of particular interest,
the symmetry imposes that if an observer at infinity sees a black hole of mass
m an observer in the other asymptotic infinity beyond the horizon (near r=0)
sees a dual mass proportional to m_P^2/m. We then show that small LQBHs are
stable and could be a component of dark matter. Ultra-light LQBHs created
shortly after the Big Bang would now have a mass of approximately 10^(-5) m_P
and emit radiation with a typical energy of about 10^(13) - 10^(14) eV but they
would also emit cosmic rays of much higher energies, albeit few of them. If
these small LQBHs form a majority of the dark matter of the Milky Way's Halo,
the production rate of ultra-high-energy-cosmic-rays (UHECR) by these ultra
light black holes would be compatible with the observed rate of the Auger
detector.
