Neutron density fluctuation and neutron-proton correlation from AMPT model

TL;DR

This study uses the AMPT model to analyze neutron density fluctuations and neutron-proton correlations in heavy-ion collisions, providing baseline references for experimental searches of critical phenomena.

Contribution

It offers the first detailed analysis of neutron fluctuations and correlations in the AMPT model across various energies and collision centralities.

Findings

Neutron-proton ratio decreases with rapidity coverage.

Ratio increases with collision centrality.

No non-monotonic energy dependence observed.

Abstract

Using the multiphase transport (AMPT) model, we study the relative neutron density fluctuation and neutron-proton correlation in matter produced by Au+Au collisions at $\sqrt{s_\text{NN}} = $7.7-200 GeV. The rapidity, centrality, and energy dependence of these two observations are also discussed. The light nuclei yield ratio of proton, deuteron, and triton $N_tN_p/N_d^2$ calculated directly from the relative neutron density fluctuation and neutron-proton correlation, decreases with rapidity coverage and increases with collision centrality. Our study also found that the ratio does not exhibit any non-monotonic behavior in collision energy dependence. Since there is no first-order phase transition or critical physics in the AMPT model, our work provides a reference for extracting the relative neutron density fluctuation from light nuclei production in experiments.