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LIGHT UNFLAVORED MESONS ($\mathit S$ = $\mathit C$ = $\mathit B$ = 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   JSON PDGID: M027

${{\mathit \eta}{(1405)}}$ $I^G(J^{PC})$ = $0^+(0^{- +})$

See also the ${{\mathit \eta}{(1475)}}$.

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▸  exp ${{\mathit \eta}{(1405)}}$ MASS

${{\mathit \eta}{(1405)}}$ MASS [1] $1408.7^{+2.0}_{-1.2}$ MeV (S = 2.2)

${{\mathit \eta}}{{\mathit \pi}}{{\mathit \pi}}$ MODE $1405.8$ $\pm2.6$ MeV (S = 2.3)

${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$ MODE (${{\mathit a}_{{{0}}}{(980)}}{{\mathit \pi}}$ or direct ${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$) $1413.5^{+2.0}_{-0.9}$ MeV (S = 1.3)

${{\mathit \pi}}{{\mathit \pi}}{{\mathit \gamma}}$ MODE $1403$ $\pm17$ MeV (S = 1.8)

4 ${{\mathit \pi}}$ MODE

${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$ MODE (unresolved)

▸  exp ${{\mathit \eta}{(1405)}}$ WIDTH

${{\mathit \eta}{(1405)}}$ WIDTH [1] $50.3$ $\pm2.5$ MeV (S = 1.6)

${{\mathit \eta}}{{\mathit \pi}}{{\mathit \pi}}$ MODE $52.6$ $\pm3.2$ MeV (S = 1.3)

${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$ MODE (${{\mathit a}_{{{0}}}{(980)}}{{\mathit \pi}}$ or direct ${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$) $49$ $\pm4$ MeV (S = 2.0)

${{\mathit \pi}}{{\mathit \pi}}{{\mathit \gamma}}$ MODE $89$ $\pm17$ MeV (S = 1.7)

4 ${{\mathit \pi}}$ MODE

${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$ MODE (unresolved)

${{\mathit \eta}{(1405)}}$ DECAY MODES

Mode   Fraction ($\Gamma_i$ / $\Gamma$) Scale Factor/ Conf. Level P(MeV/c)   $\Gamma_{1}$ ${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$ seen 424   $\Gamma_{2}$ ${{\mathit \eta}}{{\mathit \pi}}{{\mathit \pi}}$ seen 562   $\Gamma_{3}$ ${{\mathit a}_{{{0}}}{(980)}}{{\mathit \pi}}$ seen 344   $\Gamma_{4}$ ${{\mathit \eta}}{({\mathit \pi}{\mathit \pi})_{{{\mathit S}-{\text{wave}}}}}$ seen     $\Gamma_{5}$ ${{\mathit f}_{{{0}}}{(980)}}{{\mathit \pi}^{0}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$     $\Gamma_{6}$ ${{\mathit f}_{{{0}}}{(980)}}{{\mathit \eta}}$ seen -1   $\Gamma_{7}$ 4 ${{\mathit \pi}}$ seen 638   $\Gamma_{8}$ ${{\mathit \rho}}{{\mathit \rho}}$ <58 $\%$ CL=99% -1   $\Gamma_{9}$ ${{\mathit \gamma}}{{\mathit \gamma}}$ 704   $\Gamma_{10}$ ${{\mathit \rho}^{0}}{{\mathit \gamma}}$ seen 491   $\Gamma_{11}$ ${{\mathit \phi}}{{\mathit \gamma}}$ 335   $\Gamma_{12}$ ${{\mathit K}^{*}{(892)}}{{\mathit K}}$ seen 122

[1] Our estimate. See the Particle Listings for details.