Quantum black holes and thermalization in relativistic heavy ion collisions

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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 Qₛ²/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.