Determination of the mixing angle between new charmonium states

TL;DR

This paper estimates the mixing angles of certain charmonium-like states using QCD sum rules, concluding that the considered models do not successfully describe these states.

Contribution

The study provides new estimates of mixing angles for $X(3872)$, $Y(4260)$, and $Y(3940)$ states, challenging previous models based on mass reproduction.

Findings

Predicted mixing angles are smaller than previous estimates.

The considered models do not successfully describe the states.

Mixing angles are estimated using QCD sum rules.

Abstract

Using the pictures for $X(3872)$ as a mixture of charmonium and molecular $D^{\ast 0}D^0$ states; $Y(3940)$ as a mixture of $\chi_{c0}$ and $D^\ast D^{\prime\ast}$ states, and $Y(4260)$ as a mixture of the tetra-quark state with charmonium states, the corresponding mixing angles are estimated within the QCD sum rules. We obtain that our predictions for the mixing angles of the $X(3872)$, $Y(4260)$ and $Y(3940)$ states are considerably smaller compared to works in which mixing angles are estimated from the condition in reproducing the the mass of these states. Our conclusion is that the considered pictures for the $X(3872)$, $Y(4260)$ and $Y(3940)$ states are not successful in describing these states.