Novel Charmonium and Bottomonium Spectroscopies due to Deeply Bound Hadronic Molecules from Single Pion Exchange

Abstract

Pion exchange in S-wave between hadrons that are themselves in a relative S-wave is shown to shift energies by hundreds of MeV, leading to deeply bound quasi-molecular states. In the case of charmed mesons $D^{\ast },D_1$ a spectroscopy arises consistent with enigmatic charmonium states observed above 4 GeV in $e^{+}{e}^{-}$ annihilation. A possible explanation of $Y(4260)\to \psi \pi \pi$ and $Y(4360)\to {\psi }^{\prime }\pi \pi$ is found. We give results for all isospin and charge-conjugation combinations, and comment on flavor exotic doubly charmed states and bottomonium analogs. A search in $D\bar{D}3\pi$ is recommended to test this hypothesis. An exotic $1^{-+}$ is predicted to occur in the vicinity of the $Y$(4260).

Comments: 14 pages, 5 figures and 5 tables