Revised ${}^3$He nuclear charge radius due to electronic hyperfine mixing

Xiao-Qiu Qi, Pei-Pei Zhang, Zong-Chao Yan +4

The significant discrepancy in the difference of squared nuclear charge radii $\Delta R^2$ of ${}^{3,4}$He obtained from electronic-atom or muonic-atom energy levels is a puzzle. In this p…