Nuclear shell structure governs short-range nucleon pairing
D Nguyen1,2, C Yero3,4, H Szumila-Vance1,5
1Thomas Jefferson National Accelerator Facility, Newport News, VA, USA.
Nature
|June 3, 2026
Summary
Nucleons form short-range-correlated pairs within atomic nuclei. This pairing is surprisingly dependent on quantum orbitals, not nuclear mass, challenging current nuclear physics models.
Area of Science:
- Nuclear Physics
- Quantum Mechanics
Background:
- Atomic nuclei are complex quantum systems governed by the strong nuclear force.
- Nucleons (protons and neutrons) can form high-momentum, short-range-correlated (SRC) pairs.
- SRC pairs are crucial for understanding the high-momentum structure of nuclear matter and the short-distance behavior of the strong interaction.
Purpose of the Study:
- To experimentally probe the formation of short-range-correlated pairs in atomic nuclei.
- To investigate the influence of nuclear shell structure, mass, and neutron-proton imbalance on SRC pair formation.
- To compare experimental findings with theoretical predictions.
Main Methods:
- Scattering of high-energy electrons from specific isotopes (40Ca, 48Ca, 54Fe).
- Selection of isotopes with distinct nuclear shell structures for targeted analysis.
- Analysis of experimental data to determine the characteristics of short-range-correlated pair formation.
Main Results:
- Short-range-correlated pairing is unexpectedly sensitive to the specific quantum orbitals occupied by nucleons.
- The dependence on occupied quantum orbitals is significantly stronger than predicted by existing theoretical models.
- Nuclear mass and neutron-proton imbalance have a lesser impact on SRC pairing than previously assumed.
Conclusions:
- Existing theoretical models may require revision, potentially incorporating new angular-momentum quantum selection rules for nucleon pairing.
- A profound link exists between the long-range nuclear shell structure and short-range nucleon-nucleon interactions.
- Experimental findings necessitate a re-evaluation of the fundamental mechanisms governing nucleon interactions within atomic nuclei.
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