Charmonium and meson-molecule hybrid tetraquarks - Vector meson width and the isospin breaking in the X(3872) decay

TL;DR

This paper investigates the isospin violation in the X(3872) decay by modeling coupled-channel two-meson scattering with a ccbar core, considering meson widths, and finds that ho\'s width enhances isospin breaking effects.

Contribution

It introduces a coupled-channel scattering model including meson widths to explain large isospin violation in X(3872) decay, aligning theoretical peaks with experimental observations.

Findings

Narrow J/;psi ho ext{ and }J/
3;psi ext{omega} peaks appear near D0D*0 threshold.

The 2 ho ext{ width enhances isospin violation by about five times.

The peak sizes of J/
3;psi ho ext{ and }J/;psi ext{omega} are comparable, consistent with experiments.

Abstract

In the X(3872) decay, both of the J/\psi\pi\pi\ and J/\psi\pi\pi\pi\ branching fractions are observed experimentally, and their sizes are comparable to each other. In order to clarify the mechanism to cause such a large isospin violation, we investigate X(3872) employing a model of coupled-channel two-meson scattering with a ccbar core. The two-meson states consist of D0Dbar*0, D+Dbar*-, J/\psi\rho, and J/\psi\omega. The effects of the \rho\ and \omega\ meson width are also taken into account. We calculate the transfer strength from the ccbar core to the final two-meson states. It is found that very narrow J/\psi\rho\ and J/\psi\omega\ peaks appear very close to the D0Dbar*0 threshold for a wide range of variation in the parameter sets. The size of the J/\psi\rho\ peak is almost the same as that of J/\psi\omega, which is consistent with the experiments. The large width of the \rho\ meson makes the originally small isospin violation by about five times larger.