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

# ${{\boldsymbol \psi}{(4260)}}$ $I^G(J^{PC})$ = $0^-(1^{- -})$

also known as ${{\mathit Y}{(4260)}}$; was ${{\mathit X}{(4260)}}$
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. Seen in radiative return from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions at $\sqrt {s }$ = $9.54 - 10.58$ GeV by AUBERT,B 2005I, HE 2006B, and YUAN 2007 , and in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions at $\sqrt {s }$ $\approx{}$ 4.26 GeV by COAN 2006 . Possibly seen by AUBERT 2006 in ${{\mathit B}^{-}}$ $\rightarrow$ ${{\mathit K}^{-}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit J / \psi}}$ . See also the review on "Spectroscopy of mesons containing two heavy quarks."
 ${{\mathit \psi}{(4260)}}$ MASS $4230 \pm8$ MeV (S = 2.9)
 ${{\mathit \psi}{(4260)}}$ WIDTH $55 \pm19$ MeV (S = 4.4)