Consequences of Heavy Quark Symmetries for Hadronic Molecules

TL;DR

This paper explores how heavy quark flavor symmetry influences the formation and identification of hadronic molecules, predicting new states and testing the molecular nature of observed exotic mesons.

Contribution

It demonstrates the predictive power of heavy quark flavor symmetry for hadronic molecules and tests the molecular hypothesis of certain exotic states.

Findings

Predicted new heavy meson molecules, including an isoscalar $1^{++}$ $Bar B^*$ state.

Suggested the $Z_c(3900)$ and $Z_c(4025)$ as charmonium partners of bottomonium states.

Proposed experimental searches for the predicted states in specific decay channels.

Abstract

Among the newly observed structures in the heavy quarkonium mass region, some are proposed to be hadronic molecules. We investigate the consequences of heavy quark flavor symmetry on these heavy meson hadronic molecules. The symmetry allows us to predict new hadronic molecules on one hand, and test the hadronic molecular assumption of the observed structures on the other hand. We explore the consequences of the flavor symmetry assuming the X(3872) and $Z_b(10610)$ as a isoscalar $D\bar D^*$ and isovector $B\bar B^*$ hadronic molecule, respectively. A series of hadronic molecules composed of heavy mesons are predicted. In particular, there is an isoscalar $1^{++}$ $B\bar B^*$ bound state with a mass of 10580 MeV which may be searched for in the $\Upsilon(1S,2S)\pi^+\pi^-\pi^0$ mass distribution; the isovector charmonium partners of the $Z_b(10610)$ and the $Z_b(10650)$ are also predicted, one of which probably corresponds to the very recently observed $Z_c(3900)$ and $Z_c(4025)$ resonances by the BESIII Collaboration.