Heavy Exotic Molecules

TL;DR

This paper reviews the formation of heavy-light exotic molecules mediated by pions, identifying specific bound states in charm and bottom sectors that correspond to known exotic particles and predicting new ones.

Contribution

It provides a theoretical framework for understanding heavy-light exotic molecules using chiral and heavy quark symmetries, linking them to observed particles and predicting new states.

Findings

Charm isosinglet $X(3872)$ identified as a bound state.

Bottom isotriplet $Z_b$ states are bound molecules.

Predicted neutral $X_b(10532)$ as a new bound state.

Abstract

We briefly review the formation of pion-mediated heavy-light exotic molecules with both charm and bottom, under the general strictures of chiral and heavy quark symmetries. The charm isosinglet exotic molecules with $J^{PC}=1^{++}$ binds, which we identify as the reported neutral $X(3872)$. The bottom isotriplet exotic with $J^{PC}=1^{+-}$ binds, and is identified as a mixed state of the reported charged exotics $Z^+_b(10610)$ and $Z^+_b(10650)$. The bound bottom isosinglet molecule with $J^{PC}=1^{++}$ is a possible neutral $X_b(10532)$ to be observed.