Zusammenfassung
The evaporation of primordial black holes provides a promising dark matter
production mechanism without relying on any non-gravitational interactions
between the dark sector and the Standard Model. In theories of ``Large'' Extra
Dimensions (LEDs), the true scale of quantum gravity, $M_*$, could be well
below the Planck scale, thus allowing for energetic particle collisions to
produce microscopic black holes in the primordial plasma at temperatures as low
as $T 100$ GeV. Additionally, LEDs modify the relationship between
black hole mass, radius, and temperature, allowing microscopic black holes to
grow to macroscopic sizes in the early Universe. In this work we study three
scenarios for the production of dark matter via LED black holes: 1) Delayed
Evaporating Black Holes (DEBHs) which grow to macroscopic sizes before
ultimately evaporating, 2) Instantly Evaporating Black Holes (IEBHs) which
immediately evaporate, and 3) stable black hole relics with a mass $M_*$ known
as Planckeons. For a given reheating temperature, $T_RH$, we show that
DEBHs produce significantly less dark matter than both IEBHs and Planckeons.
IEBHs are able to produce the observed relic abundance of dark matter so long
as the reheating scale is in the range $10^-2 T_RH/M_* łeq
10^-1$. We calculate the average speed for the resulting dark matter and show
that it would be sufficiently cold for all dark matter masses $m_dm \gtrsim
10^-4$ GeV. This mechanism is viable for any scale of quantum gravity in the
range $10^4\, GeV M_* M_Pl$ and for any number of LEDs.
Nutzer