On the possibility of Deeply Bound Hadronic Molecules from single Pion Exchange

TL;DR

This paper explores the potential for deeply bound hadronic molecules formed via single pion exchange, suggesting they could explain certain enigmatic charmonium states observed in experiments.

Contribution

It proposes a novel mechanism for forming deeply bound hadronic molecules through S-wave pion exchange, offering a new perspective on charmonium spectroscopy.

Findings

Pion exchange can cause significant energy shifts in hadron pairs.

A spectroscopy of quasi-molecular states may explain Y(4260) and Y(4360).

Recommendations for experimental searches in specific decay channels.

Abstract

Pion exchange in S-wave between hadrons that are themselves in a relative S-wave can shift energies by hundreds of MeV. In the case of charmed mesons $D,D^*,D_0,D_1$ a spectroscopy of quasi-molecular states may arise consistent with enigmatic charmonium states observed above 4 GeV in $e^+e^-$ annihilation. A possible explanation of $Y(4260)\to \psi\pi\pi$ and $Y(4360) \to \psi'\pi\pi$ is found. Searches in $D\bar{D}3\pi$ channels as well as B decays are recommended to test this hypothesis.