Studies of the X(3872) at Belle II

TL;DR

This paper reports the re-discovery of the enigmatic X(3872) resonance at Belle II and discusses future measurement plans to better understand its nature, building on decades of prior experimental and theoretical efforts.

Contribution

It presents the first re-discovery of X(3872) at Belle II and outlines future measurement strategies to explore its properties.

Findings

X(3872) re-discovered at Belle II

Confirmation of its decay modes and production mechanisms

Plans for detailed future studies

Abstract

The X(3872) is one of the most puzzling resonances ever observed. First seen by the Belle Collaboration in 2003, it solicited the effort of a hundred of experimental physicists and dozens of theorists, who nowadays are trying yet to shed light on the nature of this peculiar resonant state. It was seen in several decay modes and different production mechanisms, and confirmed by several experiments, so it is well established, and recently is addressed as the $\chi_{c1} (3872)$. Here we report about a re-discovery of the X(3872) with early Belle II data, and discuss plans for future measurements once the full integrated planned luminosity will be achieved by Belle II.