Atomic nuclei exhibit multiple energy scales simultaneously – ranging from hundreds down to fractions of a megaelectronvolt. A new study demonstrates that these drastically different scales can be explained through calculations based on the strong nuclear force. The research also predicts that the atomic nucleus neon-30 exhibits several coexisting shapes.
“This discovery is incredibly important for understanding the stability limits of visible matter and how they can be anchored in our theory of the strong force,” says Christian Forssén, professor at the Department of Physics at Chalmers University of Technology.
Together with Andreas Ekström, professor at the same department, they have been part of the research group that has now published their findings in Physical Review X, a scientific journal from the American Physical Society (APS). In addition to Chalmers, the researchers behind the study are active at Oak Ridge National Laboratory and the University of Tennessee in the United States.
The Chalmers researchers contributed by constructing the model for the strong force that binds protons and neutrons within the atomic nucleus and by developing emulation methods to analyse how components of the strong force influence the formation of deformed atomic nuclei.
Multiscale phenomena linked to the strong nuclear force
Atomic nuclei are characterised by binding energies in the hundreds of megaelectronvolts while simultaneously exhibiting collective excitations measured in fractions of a megaelectronvolt. The research group's extensive theoretical analysis now demonstrates that this multiscale physics can be explained through calculations grounded in a microscopic description of the strong nuclear force. The study also predicts that the neon-30 nucleus exhibits coexisting spherical and deformed shapes.
Multiscale nuclear phenomena have been observed for a long time, but tying these phenomena closer to the fundamental theory of the strong nuclear force, quantum chromodynamics, has been a significant challenge. The strong force is central to all visible matter in the universe, and a deeper understanding of it can explain everything from how elements are formed in the universe to the quantum mechanical structure and binding of atomic nuclei.
New computational methods
The research team has developed new computational methods that make it possible to analyse the connection between multiscale and emergent phenomena and the fundamental theory that describes the strong force.
The methods revolve around effective theories of quantum chromodynamics and model order reduction for highly accurate emulation of solutions to the Schrödinger equation. The researchers applied two- and three-nucleon forces in an approach that first breaks and then restores rotational symmetry in the neon-30 nucleus, and then developed an emulator to study the strong force’s parameter dependencies in the wave function of the atomic nucleus.
“Our new methods, combined with statistical analyses, link the microscopic description of atomic nuclei and the strong force. This is an important step in our continued efforts to predict the properties of atomic nuclei across the entire nuclide chart,” says Andreas Ekström.
About the research
The article Multiscale physics of atomic nuclei from first principles was published in Physical Review X, on February 10 2025. It is written by Z. H. Sun, A. Ekström, C. Forssén, G. Hagen, G. R. Jansen and T. Papenbrock.
Read more about the findings in a “Physics Viewpoint” by APS: How does a nucleus get its shape?
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- Full Professor, Subatomic, High Energy and Plasma Physics, Physics
- Professor, Subatomic, High Energy and Plasma Physics, Physics