${\boldsymbol {\boldsymbol c}}$ ${\boldsymbol {\overline{\boldsymbol c}}}$ MESONS(including possibly non- ${\boldsymbol {\boldsymbol q}}$ ${\boldsymbol {\overline{\boldsymbol q}}}$ states) INSPIRE search

# ${{\boldsymbol \chi}_{{c1}}{(3872)}}$ $I^G(J^{PC})$ = $0^+(1^{+ +})$

also known as ${{\mathit X}{(3872)}}$
This state shows properties different from a conventional ${{\mathit q}}{{\overline{\mathit q}}}$ state. A candidate for an exotic structure. See the review on non- ${{\mathit q}}{{\overline{\mathit q}}}$ states. First observed by CHOI 2003 in ${{\mathit B}}$ $\rightarrow$ ${{\mathit K}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit J / \psi}{(1S)}}$ decays as a narrow peak in the invariant mass distribution of the ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit J / \psi}{(1S)}}$ final state. Isovector hypothesis excluded by AUBERT 2005B and CHOI 2011 . AAIJ 2013Q perform a full five-dimensional amplitude analysis of the angular correlations between the decay products in ${{\mathit B}^{+}}$ $\rightarrow$ ${{\mathit \chi}_{{c1}}{(3872)}}{{\mathit K}^{+}}$ decays, where ${{\mathit \chi}_{{c1}}{(3872)}}$ $\rightarrow$ ${{\mathit J / \psi}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ and ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ , which unambiguously gives the $\mathit J{}^{PC} = 1{}^{++}$ assignment under the assumption that the ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ and ${{\mathit J / \psi}}$ are in an ${\mathit S}{\mathrm -wave}$. AAIJ 2015AO extend this analysis with more data to limit ${\mathit D}{\mathrm -wave}$ contributions to $<$ 4$\%$ at 95$\%$ CL. See the review on Spectroscopy of Mesons Containing Two Heavy Quarks.''
 ${{\mathit \chi}_{{c1}}{(3872)}}$ MASS FROM ${{\mathit J / \psi}}{{\mathit X}}$ MODE $3871.69 \pm0.17$ MeV
 ${{\mathit \chi}_{{c1}}{(3872)}}$ MASS FROM ${{\overline{\mathit D}}^{*0}}{{\mathit D}^{0}}$ MODE
${\boldsymbol m}_{{{\boldsymbol \chi}_{{c1}}{(3872)}}}–{\boldsymbol m}_{{{\boldsymbol J / \psi}}}$
 ${\mathit m}_{{{\mathit \chi}_{{c1}}{(3872)}}}–{\mathit m}_{{{\mathit J / \psi}}}$ $775 \pm4$ MeV
 ${\mathit m}_{{{\mathit \chi}_{{c1}}{(3872)}}}–{\mathit m}_{{{\mathit \psi}{(2S)}}}$
 ${{\mathit \chi}_{{c1}}{(3872)}}$ WIDTH $<1.2$ MeV  CL=90.0%
 ${{\mathit \chi}_{{c1}}{(3872)}}$ WIDTH FROM ${{\overline{\mathit D}}^{*0}}{{\mathit D}^{0}}$ MODE