Thermal, chemical and spectral equilibration in heavy-ion collisions

We have considered the equilibration in relativistic heavy ion collisions at energies 1–7 A GeV using our transport model. We applied periodic boundary conditions to close the system in a box. We found that the thermal equilibration takes place in the first 20–40 fm/c whose time is comparable to the duration of a heavy ion collision. The chemical equilibration is a much slower process and the system does not equilibrate in a heavy ion collision. We have shown that in the testparticle simulation of the Boltzmann equation the mass spectra of broad resonances follow instantaneously their in-medium spectral functions as expected from the Markovian approximation to the Kadanoff–Baym equations employed via the (local) gradient expansion.