${{\mathit X}{(1835)}}$ 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
2016J
BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$
$1844$ $\pm9$ ${}^{+16}_{-25}$ 2
ABLIKIM
2015T
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
2018I
BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \phi}{(1020)}}$
$1909.5$ $\pm15.9$ ${}^{+9.4}_{-27.5}$ 4
ABLIKIM
2016J
BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$
$1842.2$ $\pm4.2$ ${}^{+7.1}_{-2.6}$ 0.6k
ABLIKIM
2013U
BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}$3 ( ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$)
$1832$ ${}^{+19}_{-5}$ $\pm26$ 5
ABLIKIM
2012D
BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit p}}{{\overline{\mathit p}}}$
$1836.5$ $\pm3.0$ ${}^{+5.6}_{-2.1}$ 4265 6
ABLIKIM
2011C
BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$
$1877.3$ $\pm6.3$ ${}^{+3.4}_{-7.4}$ 7
ABLIKIM
2011J
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
2005R
BES2 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \eta}^{\,'}}$
$1831$ $\pm7$ 10, 9
ABLIKIM
2005R
BES2 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit p}}{{\overline{\mathit p}}}$
$1859$ ${}^{+3}_{-10}$ ${}^{+5}_{-25}$ 9
BAI
2003F
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.
References