Production of $X(3872)$ at High Multiplicity

TL;DR

This paper challenges previous assumptions about the production of the $X(3872)$ meson, proposing a revised model that better fits experimental data and supports its interpretation as a loosely bound charm-meson molecule.

Contribution

It introduces a modified comover interaction model that accurately describes $X(3872)$ production dependence on multiplicity, aligning with the molecular hypothesis.

Findings

Modified model fits LHCb data well

Supports $X(3872)$ as a loosely bound molecule

Reveals breakup cross section is insensitive to binding energy

Abstract

The dependence of the production of the $X(3872)$ meson on the hadron multiplicity in $pp$ collisions has been used as evidence against $X$ being a charm-meson molecule. The argument is based in part on the incorrect assumption that the cross section for the breakup of $X$ by scattering with comovers can be approximated by a geometric cross section inversely proportional to the binding energy of $X$. The breakup cross section should instead be approximated by the probability-weighted sum of the cross sections for the scattering of comoving pions from the charm-meson constituents of $X$, which is insensitive to the binding energy. A simple modification of the comover interaction model gives excellent fits to the data from the LHCb collaboration on the multiplicity dependence of the production of $X$ and $\psi(2S)$ using parameters compatible with $X$ being a loosely bound charm-meson molecule.