Using the decay \psi(4160) -> X(3872) \gamma\ to probe the molecular content of the X(3872)

TL;DR

This paper proposes using the decay 160  X(3872)   1 to investigate whether the X(3872) is primarily a molecular state or has charmonium-like properties, aiding understanding of its structure.

Contribution

It introduces an effective field theory approach to analyze the X(3872) production in 160 decay, suggesting polarization and angular distributions as probes of its internal structure.

Findings

Angular distribution of the photon correlates with the 160 polarization.

The correlation can distinguish between short-distance and long-distance effects.

Potential measurement by BESIII could clarify the X(3872) nature.

Abstract

The X(3872) has non-charmonium-like properties, such as decay processes that seem to violate isospin, and a mass that lies unexpectedly close to the neutral-D-plus-neutral-D-excited-state threshold. An EFT that includes both charmonium-like (short distance) and molecule-like (meson bound state) properties is used to analyze the X(3872) as it is produced in the decay of \psi(4160). This is a route that BESIII may be able to measure. We find that the correlation between the angular distribution of the outcoming photon (or X(3872)) and the polarization of the \psi(4160) source may be used to provide information on whether short-distance or long-distance effects dominate.