Breakthrough in High-Energy Nuclear Physics Research: Chinese Research Team Leverages CERN's Large Hadron Collider to Reveal How Nuclear Geometry Influences Matter Flow

Relying on the A Large Ion Collider Experiment (ALICE) at the Large Hadron Collider (LHC), the research team led by Professor Li Xiaomei at the National Key Laboratory of Nuclear Data, China Institute of Atomic Energy (CIAE), in international collaboration with the team led by Professor Zhou You at the Niels Bohr Institute, University of Copenhagen, Denmark, conducted research. The joint team studied the Oxygen-16 (Oxygen-16, $^{16}\text{O}$) and Neon-20 (Neon-20, $^{20}\text{Ne}$) light-nucleus collision system and achieved important progress regarding collective flow phenomena dominated by nuclear structure, confirming that the spatial geometric configuration of atomic nuclei can directly regulate the laws of matter flow in high-energy nuclear collisions, providing key experimental constraints for improving relativistic heavy-ion collision theory and resolving microscopic nuclear structure.

High-energy relativistic nuclear collision experiments can generate high-temperature, high-density Quark-Gluon Plasma (QGP) under extreme conditions, making them an ideal platform for simulating the phase evolution of the early universe and probing the fundamental interactions inside atomic nuclei. After collisions occur, the angular distribution characteristics of final-state emitted particles retain the initial collision geometry information, and the physics community generally uses the physical quantity known as anisotropic flow to quantitatively analyze its spatial evolution behavior.

In the earlier stage, the joint team had completed Xenon-129 (Xenon-129, $^{129}\text{Xe}$) collision experiments relying on the ALICE experiment, and the extracted microscopic nuclear structure parameters were highly consistent with measurement conclusions in the field of low-energy nuclear physics; at the same time, researchers used the A Multi-Phase Transport model (AMPT) to conduct systematic numerical simulations of Lead-208 (Lead-208, $^{208}\text{Pb}$) colliding with Oxygen-16 and Neon-20 respectively, theoretically demonstrating the mechanism by which anisotropic flow responds sensitively to nuclear geometry, and the related work has previously been published successively in Physics Letters B.

Building on this foundation, the joint team further advanced experimental measurements of light-nucleus collisions between Oxygen-16 and Neon-20. The measured results show that because the Neon-20 nucleus exhibits a unique prolate ellipsoidal deformation characteristic, the anisotropic flow produced by the two collision systems shows significant physical differences, and the calculated data agree well with theoretical microscopic models, strongly confirming the dominant role of nuclear geometry in the final-state particle flow patterns and opening an empirical path for testing models of quark-level structure within nuclei.

The research results, titled "Experimental Evidence for Nuclear Geometry-Driven Anisotropic Flow in Oxygen—Oxygen and Neon—Neon Collisions," have been published in the international top physics journal Physical Review Letters (PRL) and selected as an "Editors' Suggestions" article. The achievement was jointly completed by Assistant Researcher Lu Zhiyong of the Institute of Nuclear Physics, China Institute of Atomic Energy, Dr. Emil Gorm Dahlbaek Nielsen of the Niels Bohr Institute, and Professor Zhou You as major contributing authors, and received funding support from the National Key R&D Program of China and other national-level science and technology programs.