中国原子能科学研究院核物理所微观输运理论研究组研究成果

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

文章标题：使用轻粒子发射探测核子有效质量分裂

DOI: https://doi.org/10.1007/s41365-023-01241-z

One sentence summary:

一句话概要：

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

这项开创性的研究利用重离子碰撞产生的轻粒子发射来解决核子有效质量分裂中长期存在的不一致问题。

Keywords:

关键词：

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

有效质量劈裂、对称能、重离子碰撞、Skyrme 相互作用

The Novelty (What)

创新性（主要内容）

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.

这项突破性的核物理研究提出了利用重离子碰撞中的轻粒子发射，可以确定核子有效质量的分裂。该研究的关键发现是，轻粒子产额之比的能谱斜率与有效质量分裂之间存在直接关系。研究人员们使用了一种全面的计算模型，即改进的量子分子动力学模型（ImQMD-Sky），来模拟⁸⁶Kr + ²⁰⁸Pb的重离子碰撞系统（其束能范围从25A到200A MeV）。这项研究揭示了有效质量分裂对重离子碰撞可观测量的重大影响。此外，该研究有可能解决从不同分析方法得到的有效质量分裂的不一致性。。

The Background (Why)

研究背景（主要原因）

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.

核子有效质量是用于描述核子（原子核的组成部分）在动量依赖势场中运动的基础参数。中子和质子的有效质量之间的差异，被称为“有效质量分裂”，在研究原初中子星的热性质和改进对称能约束中起着至关重要的作用。然而，在这一关键现象的理解中，存在着一些不一致。一些研究显示中子的有效质量大于质子的，而其他分析则与此相反。这些不一致突显出这个领域中的关键知识存在很大的差异，可能的原因是不同的方法可能反映了在不同的密度和动量区域的有效质量分裂。本研究旨在通过使用重离子碰撞的轻粒子发射作为探测核子有效质量分裂的新方法来解决这种不一致性。该研究所提出的方案可以促进理解目前对于核子有效质量劈裂认识上的差异，以及推进了我们对核物理的关键领域（如原初中子星的热性质）的理解。

The SDG impact (Big Why)

SDG影响力（研究意义）

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.

介质中的核力对于准确预言远离β-稳定线原子核的性质以及理解中子星的形成及演化至关重要。作为一种非凡的天体，中子星握有解决许多宇宙之谜的关键。但是，我们对中子星的理解仍处于起步阶段。本研究的成果有助于我们更深入地理解丰中子核的性质以及中子星的性质和冷却速率，为天体物理研究带来了进展。这项研究推动了核物理和天体物理领域的科学研究和创新，与联合国可持续发展目标9 - "工业，创新和基础设施"的理念高度一致。