Exotic mesons

We discuss possible exotic structure interpretations of the scalar mesons f 0 ( 1370 ) , f 0 ( 1500 ) and f 0 ( 1710 ) and the charmonium-like state X ( 3872 ) . The scalars are shown to result from a scheme where the excited quarkonia Q Q ̄ configurations mix with the lowest lying glueball. Within an effective chiral Lagrangian approach the strong decays of these states are shown to be consistent within this structure assumption. We also discuss the role of the scalar resonances f 0 ( 1370 ) , f 0 ( 1500 ) and f 0 ( 1710 ) in the strong and radiative three-body decays of J / ψ , presenting further tests for this scenario. The charmonium-like X ( 3872 ) is assumed to consist dominantly of molecular hadronic components with an additional small admixture of a charmonium configuration. A potential model based on meson exchange is able to generate weak binding of the molecular hadronic components. The observed radiative ( γ J / ψ and γ ψ ( 2 s ) ) and strong ( J / ψ 2 π and J / ψ 3 π ) decays are shown to be consistent with the molecular structure assumption of the X ( 3872 ) .