Abstract
In this paper it is proposed that the charged charmonium-like state is a resonance above the threshold from the interaction. The interaction is described by the one-boson exchange model with light meson exchanges plus a short-range exchange. The scattering amplitude is calculated within a Bethe-Salpeter equation approach, and the poles near the threshold are searched. In the isoscalar sector, two poles found under the threshold—i.e., bound states—have the quantum numbers and . The latter can be related to the . In the isovector sector, a bound state with is found with a large cutoff at about 3 GeV. If a cutoff at about 2 GeV is adopted with which a pole carrying the quantum number of the is produced at an energy of about 3871 MeV, the pole for the bound state with runs across the threshold to a second Riemann sheet and becomes a resonance above the threshold, which can be identified with the . With such a cutoff, the invariant mass spectrum is also investigated and the experimental results found by BESIII can be reproduced.
- Received 22 May 2015
DOI:https://doi.org/10.1103/PhysRevD.92.034004
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