Quantum theory of nonequilibrium processes II. Application to nuclear collisions

Abstract

In the high-energy ( E lab≥200 MeV/nucl) heavy ion-collisions, the quantum uncertainty of nucleon energies, given by the collision frequency, is of the order of (50–100) MeV. At hundreds MeV/nucl beam energies, the uncertainty is comparable with nucleon energies in the equal ion-velocity frame, indicating a quantum character of the dynamics. The quantum dynamics of a collision process is examined using nonequilibrium Green's function methods. Numerical calculations of collisions in an interpenetrating nuclear matter model, at the energy E lab=400 MeV/nucl, are performed. Comparison of the quantum dynamics, with the classical Markovian dynamics from the Boltzmann equation, reveals effects of the ill-defined nucleon energies in the nucleon momentum distribution. It is shown that the quantum dynamics proceeds twice as slow as Boltzmann dynamics, but the off-shell kinematics compensates for this somewhat.