Radiative decay of the X(3872) as a mixed molecule-charmonium state in QCD Sum Rules

TL;DR

This paper uses QCD sum rules to analyze the radiative decay width of the X(3872) meson, suggesting it is a mixed state of charmonium and molecular components, with results aligning with experimental data.

Contribution

It provides a novel calculation of the X(3872) decay width considering a mixed molecular-charmonium structure using QCD sum rules.

Findings

Branching ratio matches experimental data within uncertainties.

Decay width consistent with mass and decay width analyses.

Supports the mixed state hypothesis for X(3872).

Abstract

We use QCD sum rules to calculate the width of the radiative decay of the meson X(3872), assumed to be a mixture between charmonium and exotic molecular $[c\bar{q}][q\bar{c}]$ states with $J^{PC}=1^{++}$. We find that in a small range for the values of the mixing angle, $5^0\leq\theta\leq13^0$, we get the branching ratio $\Gamma(X\to J/\psi\gamma)/\Gamma(X\to J/\psi\pi^+\pi^-)=0.19\pm0.13$, which is in agreement, with the experimental value. This result is compatible with the analysis of the mass and decay width of the mode $J/\psi(n\pi)$ performed in the same approach.