Transport model analysis of the pion interferometry in Au+Au collisions at E =1.23 GeV/nucleon

Within the framework of the Ultra-relativistic Quantum Molecular Dynamics model, the effects of resonance decay widths, in-medium nucleon-nucleon (in)elastic cross sections, and potentials on the pion Hanbury-Brown-Twiss (HBT) intensity interferometry in central Au+Au collisions at E = 1.23 GeV/nucleon are investigated. The results show that the pion emission source is visibly influenced by the Δ particles with small invariant masses, i.e., with long resonance lifetimes. Furthermore, the pion HBT radii are found to be insensitive to the nucleon-nucleon (in)elastic cross sections, while the measured rapidity distributions of the charged pions are sensitive to the nucleon-nucleon (in)elastic cross sections and can be much better reproduced by considering a reduction factor on the nucleon-nucleon inelastic cross sections. The observed charge-sign difference of the source radii, especially in outward and sideward directions, can be qualitatively explained by simulations with the potential contributions, especially including the Coulomb potential of mesons. The present work demonstrates that the potential updates play important roles in describing the measured HBT radii and duration-time-related radii ratios when understanding the dynamics in relativistic heavy-ion collisions at ∼GeV beam energies.