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

# ${{\boldsymbol \eta}^{\,'}{(958)}}$ $I^G(J^{PC})$ = $0^+(0^{- +})$

 ${{\mathit \eta}^{\,'}{(958)}}$ MASS $957.78 \pm0.06$ MeV
 ${{\mathit \eta}^{\,'}{(958)}}$ WIDTH $0.188 \pm0.006$ MeV
${{\boldsymbol \eta}^{\,'}{(958)}}$ $\rightarrow$ ${{\boldsymbol \eta}}{{\boldsymbol \pi}}{{\boldsymbol \pi}}$ DECAY PARAMETERS $\vert$MATRIX ELEMENT$\vert ^2$ = $\vert$1 + $\alpha {}\boldsymbol Y\vert ^2$ + $\boldsymbol C{}\boldsymbol X$ + $\boldsymbol D{}\boldsymbol X{}^{2}$
 $\mathit Re(\alpha$) decay parameter
 $\mathit Im(\alpha$) decay parameter
 $\mathit C$ decay parameter
 $\mathit D$ decay parameter
${{\boldsymbol \eta}^{\,'}{(958)}}$ $\rightarrow$ ${{\boldsymbol \eta}}{{\boldsymbol \pi}}{{\boldsymbol \pi}}$ DECAY PARAMETERS $\vert$MATRIX ELEMENT$\vert ^2$ ${}\propto$ 1 + $\boldsymbol a~Y$ + $\boldsymbol b~Y{}^{2}$ + $\boldsymbol c~X$ + $\boldsymbol d~X{}^{2}$
 $\mathit a$ decay parameter
 $\mathit b$ decay parameter
 $\mathit c$ decay parameter
 $\mathit d$ decay parameter
${{\boldsymbol \eta}^{\,'}{(958)}}$ $\beta$ PARAMETER $\vert$MATRIX ELEMENT$\vert ^2$ = (1 + 2$\beta {{\boldsymbol Z}}$)
 $\beta$ decay parameter $-0.61 \pm0.08$  (S = 1.2)
${{\boldsymbol \eta}^{\,'}{(958)}}{}^{C}$-NONCONSERVING DECAY PARAMETER
 DECAY ASYMMETRY PARAMETER FOR ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ $-0.03 \pm0.04$
 ${{\mathit \eta}^{\,'}{(958)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ TRANSITION FORM FACTOR SLOPE $1.62 \pm0.17$ GeV${}^{-2}$
 constrained fit information