Hidden charm dynamically generated resonances and the $e^{+}{e}^{-}\to J/\psi D\bar{D}$, $J/\psi D{\bar{D}}^{\ast }$ reactions

Abstract

We analyze two recent reactions of Belle, producing $D\bar{D}$ and $D{\bar{D}}^{\ast }$ states that have an enhancement of the invariant $D\bar{D}$, $D{\bar{D}}^{\ast }$ mass distribution close to threshold, from the point of view that they might be indicative of the existence of a hidden charm scalar and an axial vector meson states below $D\bar{D}$ or $D{\bar{D}}^{\ast }$ thresholds, respectively. We conclude that the data is compatible with the existing prediction of a hidden charm scalar meson with mass around 3700 MeV, though other possibilities cannot be discarded. The peak seen in the $D{\bar{D}}^{\ast }$ spectrum above threshold is, however, unlikely to be due to a threshold enhancement produced by the presence, below threshold, of the hidden charm axial vector meson X(3872).

Comments: 5 pages, 5 figures, 2 tables