Quantum Black Holes and Thermalization in Relativistic Heavy Ion Collsions

A new thermalization scenario for heavy ion collisions is discussed. It is based on the Hawking–Unruh effect: an observer moving with an acceleration a experiences the influence of a thermal bath with an effective temperature T = a/2π, similar to the one present in the vicinity of a black hole horizon. In the case of heavy ion collisions, the acceleration is caused by a pulse of chromo–electric field E ∼ Q2s/g (Qs is the saturation scale, and g is the strong coupling), the typical acceleration is a ∼ Qs, and the heat bath temperature is T ≃ Qs/2π ∼ 200 MeV. In nuclear collisions at sufficiently high energies the effect can induce a rapid thermalization over the time period of τ ∼ π/Qs accompanied by phase transitions. A specific example of chiral symmetry restoration induced by the chromo–electric field is considered; it is mathematically analogous to the phase transition occurring in the vicinity of a black hole.