Article title: Probing nucleon effective mass splitting with light particle emission

DOI:10.1007/s41365-023-01241-z

One sentence summary:

This groundbreaking research utilizes light particle emissions from heavy-ion collisions to resolve longstanding inconsistencies in nucleon effective mass splitting.

Keywords:

Effective mass splitting, Symmetry energy, Heavy-ion collisions, Skyrme interaction

The Novelty

This groundbreaking study in nuclear physics leverages the emission of light particles in heavy-ion collisions to uniquely probe nucleon effective mass splitting. The study's key finding is the discovery of a direct relationship between the slopes of the spectra of certain yield ratios and the effective mass splitting. The researchers used a comprehensive computational model, the improved quantum molecular dynamics model (ImQMD-Sky), to simulate the ⁸⁶Kr + ²⁰⁸Pb heavy-ion collision system at beam energies ranging from 25A to 200A MeV. This work sheds light on the significant impact of effective mass splitting on heavy-ion collision observables. Moreover, it could resolve the discrepancy in effective mass splitting obtained from different analytical methods.

The Background

Nucleon effective mass is a fundamental parameter used to describe the motion of nucleons, the components of an atomic nucleus, in a momentum-dependent potential. A disparity in the effective masses of neutrons and protons, known as the "effective mass splitting," plays a vital role in studying thermal properties of protoneutron stars and improving the symmetry energy constraints. There have been inconsistencies in understanding this crucial phenomenon - while one set of studies indicates that the neutron effective mass is greater than the proton's, other analyses contradict this. These discrepancies underscore the crucial knowledge gap in this field, suggesting that different methods might reflect effective mass splitting at varied densities and momentum regions. Hence, this study aimed to resolve this inconsistency by using light particle emission from heavy-ion collisions as a new method to probe the nucleon effective mass splitting. The proposed solution carries significant impact as it not only fills the existing knowledge gap, but also advances our understanding of critical areas of nuclear physics, such as the thermal properties of protoneutron stars.

The SDG impact

Nuclear force in medium is important not only for predicting the properties of nuclei away from the beta-stability, but also for understanding the properties of neutron stars. As theextraordinary celestial bodies hold the key to numerous cosmic mysteries, our understanding of neutron stars is still in its early stages. The output of this study leads to better comprehension of the properties neutron-rich nuclei and cooling rates of these stars, providing advancements in astrophysical research. Thus, this study is well-aligned with UNSDG 9 - "Industry, Innovation, and Infrastructure" by promoting scientific research and innovation in the field of nuclear physics and astrophysics.

Graphical Abstract