Investigating different structures for the $X(3872)$

TL;DR

This paper uses QCD spectral sum rules to explore various structural hypotheses for the X(3872) meson, focusing on its narrow width and possible quark configurations.

Contribution

It provides a comparative analysis of different currents and their implications for the structure of X(3872) within the QCD sum rule framework.

Findings

Four-quark and molecular structures struggle to explain the narrow width.

Special color configurations are required for these structures to match observed properties.

The study narrows down plausible models for X(3872)'s internal structure.

Abstract

Using the QCD spectral sum rule approach we investigate different currents with $J^{PC}=1^{++}$, which could be associated with the $X(3872)$ meson. Our results indicate that, with a four-quark or molecular structure, it is very difficult to explain the narrow width of the state unless the quarks have a special color configuration.