Impact on Final-State Bulk Observables in Heavy-Ion Collisions from an Extended MC Glauber Model of Quantum Rotors

Abstract

Nuclear structure is closely connected to anisotropic flow in central heavy-ion collisions (HICs), so flow observables provide important probes for constraining nuclear deformation. Conventional Monte Carlo (MC) models typically describe deformed nuclei as classical rotors with definite orientations, whereas the ground states of even--even nuclei with $J=0$ are rotationally invariant. Motivated by the importance of rotational symmetry restoration, we systematically investigate symmetric collisions involving the representative even--even nuclei $^{20}\mathrm{Ne}$, $^{28}\mathrm{Si}$, $^{96}\mathrm{Ru}$, and $^{238}\mathrm{U}$ using an extended MC Glauber model that incorporates quantum superposition of nuclear orientations. In the final state, the quantum treatment suppresses elliptic flow $v_2\{2\}$, with the strongest effect observed in ultra-central Ne+Ne collisions. Quantum superposition further induces system-dependent changes in normalized symmetric cumulants and shifts the Pearson correlation between $v_2^2$ and $[p_T]$ toward the corresponding near-spherical reference values. Moreover, the quantum treatment modifies cross-system flow ratios and the U+U/Au+Au covariance ratio used experimentally to constrain nuclear deformation parameters. Our results suggest that the quantum-rotor treatment may affect the interpretation of nuclear structure information inffered from heavy-ion collision final-state observables.