LIGHT UNFLAVORED MESONS($\boldsymbol S$ = $\boldsymbol C$ = $\boldsymbol B$ = 0) For $\mathit I = 1$ (${{\mathit \pi}}$, ${{\mathit b}}$, ${{\mathit \rho}}$, ${{\mathit a}}$): ${\mathit {\mathit u}}$ ${\mathit {\overline{\mathit d}}}$, ( ${\mathit {\mathit u}}$ ${\mathit {\overline{\mathit u}}}−$ ${\mathit {\mathit d}}$ ${\mathit {\overline{\mathit d}}})/\sqrt {2 }$, ${\mathit {\mathit d}}$ ${\mathit {\overline{\mathit u}}}$;for $\mathit I = 0$ (${{\mathit \eta}}$, ${{\mathit \eta}^{\,'}}$, ${{\mathit h}}$, ${{\mathit h}^{\,'}}$, ${{\mathit \omega}}$, ${{\mathit \phi}}$, ${{\mathit f}}$, ${{\mathit f}^{\,'}}$): ${\mathit {\mathit c}}_{{\mathrm {1}}}$( ${{\mathit u}}{{\overline{\mathit u}}}$ $+$ ${{\mathit d}}{{\overline{\mathit d}}}$ ) $+$ ${\mathit {\mathit c}}_{{\mathrm {2}}}$( ${{\mathit s}}{{\overline{\mathit s}}}$ ) INSPIRE search

# ${{\boldsymbol \pi}^{0}}$ $I^G(J^{PC})$ = $1^-(0^{- +})$

We have omitted some results that have been superseded by later experiments. The omitted results may be found in our 1988 edition Physics Letters B204 1 (1988).
 ${{\mathit \pi}^{0}}$ MASS $134.9768 \pm0.0005$ MeV (S = 1.1)
 ${\mathit m}_{{{\mathit \pi}^{\pm}}}–{\mathit m}_{{{\mathit \pi}^{0}}}$ $4.5936 \pm0.0005$ MeV
 ${{\mathit \pi}^{0}}$ MEAN LIFE $(8.52 \pm0.18) \times 10^{-17}$ s (S = 1.2)
${{\boldsymbol \pi}^{0}}$ ELECTROMAGNETIC FORM FACTOR
 LINEAR COEFFICIENT OF ${{\mathit \pi}^{0}}$ ELECTROMAGNETIC FORM FACTOR $0.0335 \pm0.0031$
For decay limits to particles which are not established, see the appropriate Search sections (${{\mathit A}^{0}}$ (axion) and Other Light Boson (${{\mathit X}^{0}}$) Searches, etc.).
 constrained fit information