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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: M085

${{\mathit X}{(1835)}}$ $I^G(J^{PC})$ = $0^+(0^{- +})$

Could be a superposition of two states, one appearing as threshold enhancement in ${{\mathit p}}{{\overline{\mathit p}}}$ the other one with a lower mass at 1835 MeV. Coupled-channel analyses with more sophisticated model are needed.

${{\mathit X}{(1835)}}$ MASS $1831.8^{+4.0}_{-2.6}$ MeV

${{\mathit X}{(1835)}}$ WIDTH $120$ $\pm70$ MeV (S = 8.8)

${{\mathit X}{(1835)}}$ DECAY MODES

Mode   Fraction ($\Gamma_i$ / $\Gamma$) Scale Factor/ Conf. Level P(MeV/c)   $\Gamma_{1}$ ${{\mathit p}}{{\overline{\mathit p}}}$ seen -1   $\Gamma_{2}$ ${{\mathit \eta}^{\,'}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ seen 627   $\Gamma_{3}$ ${{\mathit \gamma}}{{\mathit \gamma}}$ not seen 916   $\Gamma_{4}$ ${{\mathit K}_S^0}$ ${{\mathit K}_S^0}$ ${{\mathit \eta}}$ seen 479   $\Gamma_{5}$ ${{\mathit \gamma}}{{\mathit \phi}{(1020)}}$ possibly seen 632   $\Gamma_{6}$ 3 ( ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$) seen 776