On $X(3872)$ production in high energy heavy ion collisions

TL;DR

This paper calculates the production cross sections of the $X(3872)$ meson in heavy ion collisions, modeling it as a molecular state and emphasizing the importance of the $Xar D^* D^*$ vertex in these processes.

Contribution

It introduces a formalism for $X(3872)$ production based on a molecular model and evaluates the significance of the $Xar D^* D^*$ vertex in cross section calculations.

Findings

The $Xar D^* D^*$ vertex significantly impacts the production cross sections.

Estimated the $Xar D^* D^*$ coupling as approximately 1.95.

Provided cross section values for $ar D^* D o ext{and} ar D^* D^* o ext{pi} X$ processes.

Abstract

We have determined the production cross sections of the $X(3872)$ state in the reactions $\bar D D\to\pi X$, $\bar D^* D\to \pi X$ and $\bar D^* D^*\to\pi X$, information which is useful for studies of the $X(3872)$ meson abundance in heavy ion collisions. We construct a formalism considering $X$ as a molecular bound state of $\bar D^0 D^{*0} - \textrm{c.c}$, $D^- D^{*+} - \textrm{c.c}$ and $D^-_s D^{*+}_s - \textrm{c.c}$. To obtain the amplitudes related to these processes we have made use of effective field Lagrangians. The evaluation of the cross section of the processes involving $D^*$ meson(s) requires the calculation of an anomalous vertex, $X\bar D^* D^*$, which has been obtained by considering triangular loops motivated by the molecular nature of $X(3872)$. Proceeding in this way, we have evaluated the cross section for the reaction $\bar D^* D\to \pi X$, and find that the diagrams involving the $X\bar D^* D^*$ vertex give a large contribution. Encouraged by this finding we estimate the $X\bar D^* D^*$ coupling, which turns out to be $1.95\pm 0.22$. We then use it to obtain the cross section for the reaction $\bar D^* D^*\to\pi X$ and find that, in this case too, the $X\bar D^* D^*$ vertex is relevant. We also discuss the role of the charged components of $X$ in the determination of the production cross sections.