Probing the structure of $\chi_{c1}(3872)$: Heavy quark symmetries at work

Abstract

More than two decades have elapsed since the discovery of $\chi_{c1}(3872)$. For this meson, previously denoted as $X(3872)$, an impressive amount of theoretical and experimental studies has been devoted concerning its properties, decays and production mechanisms. Despite the extensive work, a full understanding of the nature of $\chi_{c1}(3872)$ is missing. I describe a theoretical framework based on the heavy quark large mass limit to analyze the radiative decays of heavy quarkonia, in particular the electric dipole transitions of $\chi_{c1}(2P)$ to $S$-wave charmonia. The results favorably compare to recent LHCb collaboration measurements for $\chi_{c1}(3872)$, if this meson is identified with $\chi_{c1}(2P)$.