Meson Level Structure Equation Theory Mass (MeV) Exper. Mass (MeV) π0 1 $\left[{\pi }^{+}\otimes {\pi }^{-}\right]\oplus \left[\left(u\oplus \underset{_}{u}\right)\otimes \left(d\oplus \underset{_}{d}\right)\right]$ (134.97) (134.97) η0 2 ${\left({\pi }^{0}\right)}_{r}\otimes {\left({\pi }^{0}\right)}_{r}=\left({\pi }^{+}\oplus {\pi }^{-}\right)\otimes \left({\pi }^{+}\oplus {\pi }^{-}\right)$ (547.95) (547.86) η' 3 $\left\{{\left({\pi }^{0}\right)}_{r}\otimes \left(\eta \right)\right\}={\left({\pi }^{0}\right)}_{r}\otimes {\left({\pi }^{0}\right)}_{r}\otimes {\left({\pi }^{0}\right)}_{r}$ (957.44) (957.78) ρ 3 $\left[{\left(d,\underset{_}{d}\right)}_{\pi }\right]\otimes \left\{\left[\left(\text{2}{\pi }^{+}\oplus {\pi }_{r}^{0}\right)\otimes \left(\text{2}{\pi }^{-}\oplus {\pi }_{r}^{0}\right)\right]\right\}$ (775.76) (775.26) ρ± 3 $\left[{\left(d,\underset{_}{d}\right)}_{\pi }\right]\otimes \left\{\left[\left(2{\pi }^{+}\oplus {\pi }_{r}^{0}\right)\otimes \left(2{\pi }^{-}\oplus {\pi }_{r}^{±}\right)\right]\right\}$ (775.76) (775.26) ω 4 $\left[{\left(d,\underset{_}{d}\right)}_{\pi }\right]\otimes \left\{\left[\left(2{\pi }^{+}\oplus 2{\pi }^{0}\right)\otimes \left(\left(2{\pi }^{-}\oplus 2{\pi }^{0}\right)\right]\right\}$ (782.33) (782.65) ${\varphi }^{0}$ 4 ${\varphi }^{0}=\left\{\left[\left(d,\underset{_}{d}\right)\otimes \left(2{\pi }^{0}\oplus \eta \right)\right]\oplus \left(\eta \right)\right\}$ (1019.87) (1019.41)