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

TL;DR

This paper investigates recent Belle reactions producing Dar D and Dar D^* states, suggesting the presence of hidden charm scalar and axial vector mesons near threshold, with data supporting a scalar meson around 3700 MeV.

Contribution

It offers a theoretical interpretation of experimental data indicating hidden charm mesons, proposing their existence below certain thresholds and analyzing the nature of observed peaks.

Findings

Data compatible with a hidden charm scalar meson near 3700 MeV.

The Dar D^* peak above threshold is unlikely due to a threshold effect from X(3872).

Other explanations for the peaks cannot be ruled out.

Abstract

We analyze two recent reactions of Belle, producing $D\bar D$ and $D\bar D^*$ states that have an enhancement of the invariant $D\bar D$, $D\bar D^*$ 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 $D\bar D^*$ 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 $D\bar D^*$ 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).