Precision Calculations of Charge Symmetry Breaking and Nuclear Radii in Light Nuclei Using Chiral Effective Field Theory

We present high-precision calculations of ground-state properties for light nuclei (A = 3–7) using chiral effective field theory (EFT) potentials at next-to-next-to-leading order (N2LO) combined with advanced quantum Monte Carlo methods. Charge-symmetry-breaking effects are explicitly included through nucleon mass difference terms and pion mass splitting contributions, enabling accurate reproduction of mirror nucleus binding energy differences. The variational Monte Carlo (VMC) and Green’s function Monte Carlo (GFMC) calculations yield binding energies for 3H,3He, 4He, 6Li, and 7Li that agree with experimental values within 0.8%relative error, including the 3H-3He binding difference of 0.76±0.02 MeV. Charge radii are calculated to within 1.5% accuracy compared to recent electron scattering measurements, with the 3H charge radius of 1.78±0.03 fm matching the experimental value of 1.755 ± 0.008 fm. Three-nucleon forces contribute 1.5 ± 0.1 MeV to 4He binding and 2.0 ± 0.2 MeV to 7Li binding, demonstrating their increasing importance for medium-mass nuclei. The systematic uncertainty analysis reveals particular sensitivity of the 3H binding energy to the three-nucleon contact term coupling constant cD (3.0 ± 0.3 MeV/unit) and of the 4He charge radius to cE(0.20 ± 0.03 fm/unit). These results validate the chiral EFT framework for nuclear structure calculations and establish a foundation for future studies of heavier systems, where three-nucleon forces and higher-order terms in the chiral expansion are expected to play increasingly significant roles. The demonstrated accuracy of 0.1 MeV for binding energies and0.02 fm for charge radii suggests this approach is ready for application to nuclear matter and neutron-rich systems.