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${{\mathit X}{(1835)}}$ MASS

INSPIRE   PDGID:

M085M

VALUE (MeV) EVTS DOCUMENT ID TECN  COMMENT $\bf{ 1826.5 {}^{+13.0}_{-3.4}}$ OUR AVERAGE $1825.3$ $\pm2.4$ ${}^{+17.3}_{-2.4}$ 1 ABLIKIM 2016 J BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$ $1844$ $\pm9$ ${}^{+16}_{-25}$ 2 ABLIKIM 2015 T BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit K}_S^0}$ ${{\mathit K}_S^0}$ ${{\mathit \eta}}$ • • We do not use the following data for averages, fits, limits, etc. • • $1839$ $\pm26$ $\pm26$ 3 ABLIKIM 2018 I BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \phi}{(1020)}}$ $1909.5$ $\pm15.9$ ${}^{+9.4}_{-27.5}$ 4 ABLIKIM 2016 J BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$ $1842.2$ $\pm4.2$ ${}^{+7.1}_{-2.6}$ 0.6k ABLIKIM 2013 U BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}$3 ( ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$) $1832$ ${}^{+19}_{-5}$ $\pm26$ 5 ABLIKIM 2012 D BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit p}}{{\overline{\mathit p}}}$ $1836.5$ $\pm3.0$ ${}^{+5.6}_{-2.1}$ 4265 6 ABLIKIM 2011 C BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$ $1877.3$ $\pm6.3$ ${}^{+3.4}_{-7.4}$ 7 ABLIKIM 2011 J BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \omega}}({{\mathit \eta}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$) $1837$ ${}^{+10}_{-12}$ ${}^{+9}_{-7}$ 231 8, 9 ALEXANDER 2010 CLEO ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit p}}{{\overline{\mathit p}}}$ $1833.7$ $\pm6.1$ $\pm2.7$ 264 ABLIKIM 2005 R BES2 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$ $1831$ $\pm7$ 10, 9 ABLIKIM 2005 R BES2 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit p}}{{\overline{\mathit p}}}$ $1859$ ${}^{+3}_{-10}$ ${}^{+5}_{-25}$ 9 BAI 2003 F BES2 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit p}}{{\overline{\mathit p}}}$ 1  From a fit of the measured ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$ lineshape that accounts for the abrupt distortion observed at the ${{\mathit p}}{{\overline{\mathit p}}}$ threshold through interference with a second previously unseen narrow resonance near 1870 MeV. The fit uses Breit-Wigner functions for the signal shapes and includes known backgrounds and contributors. 2  Decay dominated by ${{\mathit f}_{{{0}}}{(980)}}{{\mathit \eta}}$ hence $\mathit I{}^{G}(\mathit J{}^{PC})$ = $0{}^{+}0{}^{-+}$. 3  From a fit to ${{\mathit \gamma}}{{\mathit \phi}}$ invariant mass. Angular analysis consistent with $\mathit J{}^{PC} = 0{}^{-+}$. Other $\mathit J{}^{PC}$ not excluded. 4  Pole mass from a fit of the measured ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$ lineshape to a Flatte formula that accounts for the abrupt distortion observed at the ${{\mathit p}}{{\overline{\mathit p}}}$ threshold; the fit also includes known backgrounds and contributors, as well as an $\mathit ad~hoc$ Breit-Wigner function (M $\approx{}$ 1919 MeV; $\Gamma $ $\approx{}$ 51 MeV) that is required for a good fit. 5  From the fit including final state interaction effects in isospin 0 ${\mathit S}{\mathrm -wave}$ according to SIBIRTSEV 2005A. Supersedes ABLIKIM 2010G. 6  From a fit of the ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$ mass distribution to a combination of ${{\mathit \gamma}}{{\mathit f}_{{{1}}}{(1510)}}$, ${{\mathit \gamma}}{{\mathit X}{(1835)}}$, and two states ${{\mathit \gamma}}{{\mathit X}{(2120)}}$ and ${{\mathit \gamma}}{{\mathit X}{(2370)}}$, for ${{\mathit M}}({{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$) $<$ 2.8 GeV,and accounting for backgrounds from non-${{\mathit \eta}^{\,'}}$ events and ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \pi}^{0}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$. 7  The selected process is ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \omega}}{{\mathit a}_{{{0}}}{(980)}}{{\mathit \pi}}$. This state may be due also to ${{\mathit \eta}_{{{2}}}{(1870)}}$ or to a combination of ${{\mathit X}{(1835)}}$ and ${{\mathit \eta}_{{{2}}}{(1870)}}$. 8  From a fit of the ${{\mathit p}}{{\overline{\mathit p}}}$ mass distribution to a combination of ${{\mathit \gamma}}{{\mathit X}{(1835)}}$, ${{\mathit \gamma}}{{\mathit R}}$ with ${{\mathit M}}({{\mathit R}}$) = 2100 MeV and ${{\mathit \Gamma}}({{\mathit R}}$) = 160 MeV, and ${{\mathit \gamma}}{{\mathit p}}{{\overline{\mathit p}}}$ phase space, for ${{\mathit M}}({{\mathit p}}{{\overline{\mathit p}}}$) $<$ 2.85 GeV. 9  Evidence for a threshold enhancement in the ${{\mathit p}}{{\overline{\mathit p}}}$ mass spectrum was also reported by ABE 2002K, AUBERT,B 2005L, and WANG 2005A in ${{\mathit B}^{+}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit K}^{+}}$, WANG 2005A in ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit K}_S^0}$ , ABE 2002W in ${{\overline{\mathit B}}^{0}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit D}^{0}}$, DEL-AMO-SANCHEZ 2012 in ${{\mathit B}}$ $\rightarrow$ ${{\mathit D}}({{\mathit D}^{*}}){{\mathit p}}{{\overline{\mathit p}}}({{\mathit \pi}}$), and WEI 2008 in ${{\mathit B}^{+}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit \pi}^{+}}$ decays. Not seen by ATHAR 2006 in ${{\mathit \Upsilon}{(1S)}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit \gamma}}$. 10  From the fit including final state interaction effects in isospin 0 ${\mathit S}{\mathrm -wave}$ according to SIBIRTSEV 2005A. Systematic errors not estimated.

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