Employing spin symmetry to disentangle different models for the XYZ states

TL;DR

This paper compares different theoretical models for recently observed charmonium-like states, using spin symmetry to distinguish their predictions and identify unique experimental signatures.

Contribution

It derives distinct spectral predictions for hadro-charmonium, tetraquark, and molecular models using spin symmetry, aiding experimental differentiation.

Findings

Hadro-charmonium predicts a lighter pseudoscalar state than Y(4260).

Models produce distinct spectral patterns.

Possible discovery channels for new states are discussed.

Abstract

In order to test different models proposed for some states discovered recently in the charmonium mass range that do not fit into the pattern predicted by the conventional quark model, we derive predictions for the spectrum within the hadro-charmonium picture, the tetraquark picture as well as the hadronic molecular approach. We exploit heavy quark spin symmetry for the hadro-charmonium and hadronic molecule scenarios. The patterns that emerge from the different models turn out to be quite distinct. For example, only within the hadro-charmonium picture a pseudoscalar state emerges that is lighter than the Y(4260). Possible discovery channels of these additional states are discussed.