Can the hyperfine mass splitting formula in heavy quarkonia be applied to the $B_c$ system?

Lei Chang, Muyang Chen, Xue-qian Li +2

The mass relation $M_{0^{+}}+3M_{1^{+\prime }}+5M_{2^{+}}=9M_{1^{+}}$ miraculously holds for the $P$-wave charmonium $(c\bar{c})$ and bottomonium $(b\bar{b})$ systems with soarin…