Abstract

In the present article we report on evidence for hadronic molecule structures in the charmonium sector. In particular we discuss the Y(3940) and the recently observed Y(4140) as heavy hadron molecule states with quantum numbers J(PC) = 0(++) or 2(++). The Y(3940) state is considered to be a superposition of D*D+*(-) and D*(0) (D*(0)) over bar, while the Y(4140) is a bound state of D-s*(+) and D-s*(-), mesons. We give predictions for both the strong Y(3940) -> J/psi omega, Y(4140) -> J/psi phi and radiative Y (3940)/Y (4140) -> gamma gamma decay widths in a phenomenological Lagrangian approach. The results for the strong hidden charm decay modes clearly support the molecular interpretation of the Y(3940) and Y(4140), while our estimates for the radiative decays provide a sensitive test for the underlying meson structure of the two Y mesons discussed here. The alternative assignment of J(PC) = 2(++) is also tested, giving similar results for the strong decay widths.