On leptonic width of X(4260)

New measurements on cross sections in $$e^+e^-\rightarrow J/\psi \pi ^+\pi ^-$$ e + e - → J / ψ π + π - , $$h_c\pi ^+\pi ^-$$ h c π + π - , $$D^0D^{*-}\pi ^++c.c.$$ D 0 D ∗ - π + + c . c . , $$\psi (2S)\pi ^+\pi ^-$$ ψ ( 2 S ) π + π - , $$\omega \chi _{c0}$$ ω χ c 0 and $$J/\psi \eta $$ J / ψ η channels have been carried out by BESIII, Belle and BABAR experiments, as well as in the $$D_s^{*+}D_s^{*-}$$ D s ∗ + D s ∗ - channel. We perform extensive numerical analyses by combining all these data available, together with those in $$D^+D^{*-}+c.c.$$ D + D ∗ - + c . c . and $$D^{*+}D^{*-}$$ D ∗ + D ∗ - channels. Though the latter show no evident peak around $$\sqrt{s}=4.230$$ s = 4.230 GeV, the missing X(4260) is explained as that it is concealed by the interference effects of the well established charmonia $$\psi (4040)$$ ψ ( 4040 ) , $$\psi (4160)$$ ψ ( 4160 ) and $$\psi (4415)$$ ψ ( 4415 ) . Our analyses reveal that the leptonic decay width of X(4260) ranges from $$\mathcal {O}(10^2)$$ O ( 10 2 ) eV to $$\mathcal {O}(1)$$ O ( 1 ) keV, and hence it is probably explained in the conventional quark model picture. That is, the X(4260) may well be interpreted as a mixture of $$4^3S_1$$ 4 3 S 1 and $$3^3D_1$$ 3 3 D 1 ($$2^3D_1$$ 2 3 D 1 ) states.