  We use black holes with a negative cosmological constant to investigate
aspects of the freeze-out temperature for hadron production in high energy
heavy-ion collisions. The two black hole solutions present in the anti-de
Sitter geometry have different mass and are compared to the data showing that
the small black hole solution is in good agreement. This is a new feature in
the literature since the small black hole in general relativity has different
thermodynamic behavior from that of the large black hole solution. We find that
the inclusion of the cosmological constant (which can be interpreted as the
plasma pressure) leads to a lowering of the temperature of the freeze-out curve
as a function of the baryochemical potential, improving the description
previously suggested by Castorina, Kharzeev, and Satz.
