Three-body collisions in Boltzmann-Uehling-Uhlenbeck theory

Aiming at a microscopic description of heavy ion collisions in the beam energy region of about $10A$ GeV, we extend the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) transport model by including a relativistic mean field, in-medium baryon-baryon cross sections, and three-body collisions. The model is then compared with experimental data for central Au+Au collisions at 2A-10A GeV and central Pb+Pb collisions at $30A$ and $40A$ GeV on the proton rapidity spectra, the midrapidity yields of π⁺,K^±, and (Λ+Σ⁰), and the transverse mass spectra of π^± and K^±. The three-body collisions increase the inverse slope parameters of the hadron m_⊥ spectra to good agreement with the data.