Chiral Symmetry and Peripheral Neutron-α Scattering
Yilong Yang1, Evgeny Epelbaum2, Jie Meng1
1Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing 100871, China.
Physical Review Letters
|November 7, 2025
Summary
Peripheral neutron-alpha scattering at low energies offers a novel method to study three-nucleon forces. Calculations show the two-pion exchange force is key for describing neutron-alpha scattering phase shifts.
Area of Science:
- Nuclear Physics
- Quantum Monte Carlo methods
- Chiral Effective Field Theory
Background:
- Understanding three-nucleon forces is crucial for nuclear structure and reactions.
- Existing models often struggle to accurately describe these complex interactions.
- Neutron-alpha scattering is a key reaction for probing nuclear forces.
Purpose of the Study:
- To propose and demonstrate neutron-alpha scattering as a sensitive probe of long-range three-nucleon forces.
- To investigate the role of chiral effective field theory in few-body systems.
- To reveal the predictive power of chiral symmetry in nuclear physics.
Main Methods:
- Ab initio quantum Monte Carlo calculations were performed.
- Two- and three-nucleon interactions were derived using chiral effective field theory up to third expansion order.
- Low-energy neutron-alpha scattering phase shifts were analyzed.
Main Results:
- The longest-range three-nucleon force, arising from two-pion exchange, significantly impacts neutron-alpha D-wave phase shifts.
- Calculations successfully described the observed scattering data.
- The study highlights the importance of including these forces for accurate nuclear predictions.
Conclusions:
- Peripheral neutron-alpha scattering is a clean and sensitive probe for long-range three-nucleon forces.
- Chiral effective field theory provides a robust framework for describing few-body nuclear systems.
- This work opens new avenues for constraining and understanding three-nucleon forces in nuclear physics.
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